阅读说明：本技术 电路部件的制造方法和电路部件 (Method for manufacturing circuit component and circuit component ) 是由 游佐敦 山本智史 后藤英斗 于 2018-06-25 设计创作，主要内容包括：本发明提供一种迎合汽车部件等的轻量化需求的电路部件。一种电路部件,包括作为含有热塑性树脂的发泡成型体的基材和形成于前述基材上的电路图形。(The invention provides a circuit component meeting the light weight requirement of automobile components and the like. A circuit member comprising a base material which is a foamed molded body containing a thermoplastic resin and a circuit pattern formed on the base material.)

1. A circuit component, comprising:

as a base material for a thermoplastic resin-containing foamed molded article, and

a circuit pattern formed on the substrate.

2. The circuit component of claim 1,

the thermoplastic resin contains a super engineering plastic,

when the circuit member is heated and the surface temperature of the circuit member is maintained at 240 to 260 ℃ for 5 minutes, the rate of change in the thickness of the circuit member due to heating is-2 to 2%.

3. The circuit component of claim 1,

the circuit component has:

the base material which contains the thermoplastic resin and the insulating heat conductive filler and has the foamed molded body with a density reduction rate of 0.5% to 10% and which has a mounting surface and a back surface opposite to the mounting surface,

the circuit pattern formed on the surface of the base material including the mounting surface, and

a mounting member mounted on the mounting surface of the base material and electrically connected to the circuit pattern;

the distance from the mounting surface to the back surface of the base material at the portion where the mounting member is mounted is 0.1mm or more.

4. The circuit component of claim 3,

the density reduction rate of the base material is 1-7%.

5. Circuit component according to claim 3 or 4,

the distance from the mounting surface to the back surface of the base material at the portion where the mounting member is mounted is more than 0.5 mm.

6. The circuit component of claim 5,

the base material has a foam cell between the mounting surface and the back surface in a portion where the mounting member is mounted.

7. Circuit component according to claim 3 or 4,

a concave portion defined by a side wall and a bottom surface is formed on the rear surface,

the mounting member is mounted on the mounting surface corresponding to the bottom surface,

the distance from the mounting surface to the bottom surface is 0.1 mm-1.5 mm.

8. The circuit component of claim 7,

the bottom surface has an area of 0.4cm for each of the mounting members arranged on the mounting surface corresponding to the bottom surface²～4cm²。

9. The circuit component of claim 7 or 8,

a non-through or through hole is formed from the mounting surface to the bottom surface, and an electroless plating film is formed on the inner wall of the hole.

10. The circuit component of claim 7 or 8,

in the portion of the substrate to which the mounting member is attached, a recess is formed in the mounting surface, and an electroless plating film is formed on the surface of the recess.

11. The circuit member according to any one of claims 3 to 10,

the circuit pattern includes an electroless plating film.

12. The circuit member according to any one of claims 3 to 11,

the heat-releasing member is not provided on the rear surface.

13. The circuit member of any of claims 3-12,

the thermoplastic resin contains a super engineering plastic.

14. The circuit member according to any one of claims 1 to 13,

the thermoplastic resin contains super engineering plastic, and the super engineering plastic contains polyphenylene sulfide or liquid crystal polymer.

15. A method of manufacturing a circuit member, characterized in that,

manufacturing an electric circuit member using a plasticizing cylinder having a plasticizing region that plasticizes and melts a thermoplastic resin to form a molten resin and a starvation region that causes the molten resin to assume a starvation state, and formed with an introduction port for introducing a physical blowing agent in the starvation region;

the manufacturing method comprises the following steps:

plasticizing and melting the thermoplastic resin in the plasticizing zone to form the molten resin,

introducing a pressurized fluid containing said physical blowing agent at a fixed pressure into said starvation zone and maintaining said starvation zone at said fixed pressure,

causing the molten resin to assume a starved state in the starvation zone,

contacting the molten resin in a starved state with the pressurized fluid containing the physical blowing agent at a fixed pressure in the starved zone while maintaining the starved zone at the fixed pressure,

molding the molten resin contacted with the pressurized fluid containing the physical foaming agent into a foamed molded body, and

forming a circuit pattern on the surface of the foam molding body;

the thermoplastic resin is super engineering plastic, and the fixed pressure is 0.5 MPa-12 MPa.

16. The method of manufacturing a circuit member according to claim 15,

the super engineering plastic contains polyphenylene sulfide or liquid crystal polymer.

17. The method of manufacturing a circuit member according to claim 15,

the super engineering plastic contains polyphenylene sulfide, and the fixed pressure is 2 MPa-12 MPa.

18. The method for manufacturing a circuit member according to any one of claims 15 to 17,

the circuit pattern comprises an electroless plating film,

the process of forming the circuit pattern on the surface of the foaming molded body comprises the following steps:

forming a catalyst activity suppressing layer containing a polymer having at least one of an amide group and an amino group on the surface of the molded foam,

heating or irradiating light to a part of the surface of the foam molding on which the catalytic activity suppression layer is formed,

imparting electroless plating catalyst to the surface of the foam molding heated or irradiated with light, and

and contacting the surface of the foam molding to which the electroless plating catalyst is applied with an electroless plating solution to form the electroless plating film on the heated portion or the light irradiated portion of the surface.

Technical Field

The present invention relates to a method for manufacturing a circuit member (molded circuit member) and a circuit member (molded circuit member).

Background

In recent years, with the trend toward weight reduction and electric driving of automobiles, there has been a trend to replace metal parts of automobiles with foamed resin parts that are lightweight and have insulation properties. Therefore, a large number of studies and practical uses have been made on a method for producing a foamed molded article (foam molding). Conventionally, polypropylene (PP) and acrylonitrile-butadiene-styrene copolymer resin (ABS) have been used as general-purpose engineering plastics (engineering plastics). Further, glass fiber reinforced resins such as polyamide 6 and polyamide 66 having a certain degree of heat resistance are also used for foam molding. The foaming agents used for foam molding are roughly classified into 2 types, physical foaming agents and chemical foaming agents, and it is difficult to use chemical foaming agents for high-melting materials. For this reason, foam injection molding methods using a high-pressure supercritical fluid as a physical foaming agent are used for foam molding of the glass fiber reinforced resin and the like having high heat resistance (for example, patent documents 1 to 3).

The general engineering plastic has a heat resistance of about 100 ℃, and super engineering plastics (special engineering plastics) such as polyphenylene sulfide (PPS) and Liquid Crystal Polymer (LCP) having a heat resistance of 150 ℃ or higher are used in applications where the general engineering plastic is used in a higher temperature environment. PPS is a special engineering plastic with excellent cost performance and fastest growing application in automobile parts. LCP is used in small components such as high-precision connectors. Patent documents 4 and 5 disclose methods for producing PPS foamed molded articles.

In recent years, MID (Molded Interconnected Device) has been put to practical use in smart phones and the like, and it is expected that the application in the automobile field will expand in the future. MID is a device in which a three-dimensional circuit is formed on the surface of a molded body using a metal film, and can contribute to weight reduction, thickness reduction, and reduction in the number of parts of a product (for example, patent documents 6 and 7).

MID mounted Light Emitting Diodes (LEDs) have also been proposed. Since the LED generates heat by being energized, heat must be radiated from the back surface, and it is important to improve the heat radiation performance of the MID. Patent documents 8 and 9 propose composite members in which an MID and a metal heat-emitting material are integrated.

Further, a method of improving the heat radiation property of a resin molded product itself by mixing a conductive filler with a resin and molding the mixture has been proposed (for example, patent document 10).

Disclosure of Invention

Problems to be solved by the invention

In order to meet the demand for weight reduction of automobile parts, molded circuit parts such as MIDs disclosed in patent documents 6 and 7 need to be further weight reduced. Therefore, it is desired to use a foamed molded article having a low specific gravity for molding a circuit member to reduce the weight of the molded circuit member. The present invention solves the above problems and provides a lightweight molded circuit component.

The methods for producing PPS foamed molded articles disclosed in patent documents 4 and 5 include a step of holding a PPS molded article in an inert gas atmosphere under pressure to allow the inert gas to permeate therethrough, and a step of heating PPS permeated with the inert gas at normal pressure to foam the PPS foamed molded article, and are so-called batch-type production methods. Therefore, the productivity is low as compared with continuous molding such as injection molding or extrusion molding.

The foam molding methods using a physical foaming agent disclosed in patent documents 1 to 3 are continuous molding with high productivity, and are foam molding techniques that do not select a resin. Therefore, in principle, it is considered that the foam molding of a special engineering plastic such as PPS can be performed by the methods disclosed in patent documents 1 to 3. However, in recent years, very high heat resistance has been required for automobile parts. According to the studies of the present inventors, it has been found that a foamed molded article produced by using a conventional high-pressure physical foaming agent and a molded circuit member using the same, as disclosed in patent documents 1 to 3, cannot obtain sufficient heat resistance even when a special engineering plastic is used as a resin material.

The present invention solves the above problems and provides a method for manufacturing a molded circuit component which includes continuous molding with high productivity, has high heat resistance, and is lightweight.

Further, if the resin molded body serving as a base material of the circuit component such as the MID has a sufficient heat radiation performance, the metal heat radiation member disclosed in patent documents 8 and 9 is not necessary, and the cost of the circuit component can be reduced. However, if it is desired to add a conductive filler such as that disclosed in patent document 10 to a thermoplastic resin to obtain heat dissipation properties required for electronic components, the fluidity of the thermoplastic resin is reduced during molding. As a result, moldability is reduced, and sufficient dimensional accuracy cannot be obtained for the resin molded article.

If the pressure holding is increased in order to improve the dimensional accuracy of the resin molded body, burrs may be generated in the resin molded body. When the burrs are generated, secondary processing for removing the burrs is required. Further, if the mold is molded by increasing the clamping pressure in order to suppress the occurrence of burrs, there is a problem that the life of the mold is shortened. These problems increase the manufacturing cost of the circuit components and reduce mass productivity.

The present invention solves these problems, and provides a circuit component (MID) using a base material of a resin molded body, which can achieve both mass productivity and heat dissipation.

Means for solving the problems

According to a first aspect of the present invention, there is provided a circuit member comprising a base material which is a foamed molded body containing a thermoplastic resin, and a circuit pattern formed on the base material.

In this embodiment, the thermoplastic resin may contain a super engineering plastic, and the rate of change in the thickness of the circuit member due to heating may be-2% to 2% when the circuit member is heated to maintain the surface temperature of the circuit member at 240 ℃ to 260 ℃ for 5 minutes. The heating of the aforementioned circuit components may be performed using a reflow oven.

In the present embodiment, the circuit member is the foamed molded body containing the thermoplastic resin and the insulating heat conductive filler and having a density reduction rate of 0.5% to 10%, and has the base material including a mounting surface and a back surface opposite to the mounting surface, the circuit pattern formed on the surface of the base material including the mounting surface, and the mounting member mounted on the mounting surface of the base material and electrically connected to the circuit pattern, and a distance from the mounting surface to the back surface may be 0.1mm or more in a portion of the base material where the mounting member is mounted. The density reduction rate of the base material may be 1 to 7%. Further, the mounting member is mounted on the base materialIn addition, a distance from the mounting surface to the back surface may exceed 0.5mm, and a foam cell (foam セル) may be provided between the mounting surface and the back surface. The rear surface may be formed with a recess defined by a side wall and a bottom surface, the mounting member may be mounted on the mounting surface corresponding to the bottom surface, and a distance from the mounting surface to the bottom surface may be 0.1mm to 1.5 mm. The area of the bottom surface of each of the mounting members disposed on the mounting surface corresponding to the bottom surface may be 0.4cm²～4cm²。

A non-through hole or a through hole may be formed from the mounting surface to the bottom surface, and an electroless plating film may be formed on an inner wall of the hole. In addition, a concave portion may be formed on the mounting surface in a portion of the base member to which the mounting member is attached, and an electroless plating film may be formed on a surface of the concave portion.

The mounting member may be an LED, and the circuit pattern may include an electroless plating film. The rear surface may not be provided with a heat radiation member. The thermoplastic resin may contain a super engineering plastic, and the super engineering plastic may contain polyphenylene sulfide or a liquid crystal polymer.

According to a second aspect of the present invention, there is provided a method for manufacturing an electrical circuit member, comprising using a plasticizing cylinder having a plasticizing region for plasticizing and melting a thermoplastic resin to form a molten resin and a starvation region for causing the molten resin to assume a starved state, the plasticizing cylinder being provided with an inlet for introducing a physical blowing agent into the starvation region; the manufacturing method comprises the following steps: plasticizing and melting the thermoplastic resin in the plasticizing area to form the molten resin, introducing a pressurized fluid containing the physical foaming agent at a fixed pressure into the starving area and maintaining the starving area at the fixed pressure, causing the molten resin to assume a starved state in the starving area, bringing the molten resin in the starving area into contact with the pressurized fluid containing the physical foaming agent at the fixed pressure in the state where the starving area is maintained at the fixed pressure, molding the molten resin in contact with the pressurized fluid containing the physical foaming agent into a foam molded body, and forming a circuit pattern on the surface of the foam molded body; the thermoplastic resin is super engineering plastic, and the fixed pressure is 0.5MPa to 12 MPa.

In this embodiment, the super engineering plastic may contain polyphenylene sulfide or a liquid crystal polymer. The super engineering plastic may contain polyphenylene sulfide, and the fixed pressure may be 2MPa to 12 MPa. The physical blowing agent may be nitrogen.

The molten resin may be pressurized by the pressurized fluid containing the physical foaming agent in the starved region, or the starved region may be kept at the constant pressure during the production of the foamed molded article. The plasticizing cylinder may have an introduction speed adjusting container connected to the introduction port, and the manufacturing method may further include supplying the pressurized fluid containing the physical foaming agent to the introduction speed adjusting container, and introducing the pressurized fluid containing the physical foaming agent at a fixed pressure from the introduction speed adjusting container to the starvation zone. The introduction port may be opened all the time, and the fixed pressure may be maintained in the introduction speed adjustment vessel and the starved area during the production of the foamed molded article.

The forming of the circuit pattern on the surface of the foamed molded article may include: forming a catalytic activity suppressing layer containing a polymer having at least one of an amide group and an amino group on the surface of the foam molded body, heating or irradiating a part of the surface of the foam molded body on which the catalytic activity suppressing layer is formed with light, applying an electroless plating catalyst to the surface of the foam molded body which has been heated or irradiated with light, and bringing the surface of the foam molded body to which the electroless plating catalyst has been applied into contact with an electroless plating solution to form the electroless plating film on a heated portion or a light-irradiated portion of the surface. The aforementioned polymer may be a hyperbranched polymer.

Effects of the invention

The invention can provide a lightweight circuit component (molded circuit component).

Drawings

Fig. 1 is a flowchart showing a method for producing a foamed molded article according to a first embodiment.

Fig. 2 is a schematic diagram showing an apparatus for producing a foamed molded article used in the first embodiment.

Fig. 3 is a flowchart showing a method of forming a circuit pattern on the surface of a foamed molded body in the first embodiment.

Fig. 4 is a diagram illustrating a method for forming a circuit pattern on the surface of a foamed molded article according to the first embodiment.

In fig. 5, fig. 5(a) is a schematic top view of a circuit component according to a second embodiment, and fig. 5(B) is a schematic cross-sectional view taken along line B1-B1 in fig. 5 (a).

Fig. 6 is a partially enlarged view of the circuit component shown in fig. 5 (b).

In fig. 7, fig. 7(a) is a top view showing a structure in the manufacturing process of the circuit part shown in fig. 5(a), and fig. 7(B) is a cross-sectional view of line B3-B3 of fig. 7 (a).

In fig. 8, fig. 8(a) is a top view showing a structure in another manufacturing process of the circuit part shown in fig. 5(a), and fig. 8(B) is a cross-sectional view of line B4-B4 of fig. 8 (a).

Fig. 9 is a schematic cross-sectional view of a circuit member of modification 1 of the second embodiment.

Fig. 10 is a schematic cross-sectional view of a circuit member of modification 2 of the second embodiment.

Detailed Description

[ first embodiment ]

The method for manufacturing a molded circuit component according to the present embodiment will be described with reference to the flowchart shown in fig. 1. In the present embodiment, first, a foam molded body is produced (steps S1 to S5 in fig. 1), and a circuit pattern is formed on the surface of the foam molded body (step S6 in fig. 1) to obtain a molded circuit member. Here, the term "molded circuit component" means a component in which an electric circuit is formed on the surface of a resin molded body.

< apparatus for producing foamed molded article >

First, a production apparatus for producing a foamed molded article used in the present embodiment will be described. In the present embodiment, a foamed molded body is produced using a production apparatus (injection molding apparatus) 1000 shown in fig. 2. The manufacturing apparatus 1000 mainly includes a plasticizing cylinder 210 having a screw 20 provided therein, a tank 100 as a physical blowing agent supply mechanism for supplying a physical blowing agent to the plasticizing cylinder 210, a mold clamping unit (not shown) having a mold, and a control device (not shown) for controlling the operation of the plasticizing cylinder 210 and the mold clamping unit. In the plasticizing cylinder 210, the molten resin that is plasticized flows from the right-hand side to the left-hand side in fig. 2. Therefore, inside the plasticizing cylinder 210 of the present embodiment, the right-hand side in fig. 2 is defined as "upstream" or "rear", and the left-hand side is defined as "downstream" or "front".

The plasticizing cylinder has a plasticizing zone 21 where the thermoplastic resin is plasticized and melted to form molten resin, and a starvation zone 23 where the molten resin assumes a starvation state on the downstream side of the plasticizing zone 21. The "starved state" is an unfilled state in which the molten resin is not filled in the starved zone 23. Therefore, a space other than the portion occupied by the molten resin exists in the starved area 23. Further, an inlet port 202 for introducing a physical foaming agent into the starved area 23 is formed, and an introduction speed adjusting container 300 is connected to the inlet port 202. The tank 100 supplies the physical foaming agent to the plasticizing cylinder 210 via the introduction speed adjusting container 300.

The manufacturing apparatus 1000 has only 1 starvation area 23, but the manufacturing apparatus used in the present embodiment is not limited to this. For example, in order to promote the penetration of the physical blowing agent into the molten resin, the apparatus may have a plurality of starved areas 23 and inlets 202 formed therein, and the physical blowing agent may be introduced into the plasticizing cylinder 210 through the plurality of inlets 202. The manufacturing apparatus 1000 is an injection molding apparatus, but the manufacturing apparatus used in the present embodiment is not limited to this, and may be an extrusion molding apparatus, for example.

< method for manufacturing molded circuit component >

(1) Plasticizing and melting of thermoplastic resin

First, the thermoplastic resin is plasticized and melted in the plasticizing zone 21 of the plasticizing cylinder 210 to form a molten resin (step S1 of fig. 1). In the present embodiment, as the thermoplastic resin, super engineering plastic (hereinafter, appropriately referred to as "special engineering plastic") is preferably used. Generally, plastics having a continuous use temperature of 150 ℃ or higher are classified as special engineering plastics, and therefore, the definition of special engineering plastics in the specification of the present application is also in accordance with this classification. Most molecular chains of the special engineering plastics contain benzene rings, so the molecular chains are coarse and hard. Even if the ambient temperature is high, the molecules are hard to move, and therefore, the heat resistance is excellent. Further, some fluororesins have excellent heat resistance even if they do not have a benzene ring structure, and are classified as special engineering plastics. Since the fluororesin is very stable in combination with carbon.

Special engineering plastics are roughly classified into amorphous (transparent) resins and crystalline resins. Examples of the amorphous (transparent) resin include polyphenylsulfone (PPSU), Polysulfone (PSU), Polyarylate (PAR), and Polyetherimide (PEI); examples of the crystalline resin include Polyetheretherketone (PEEK), polyphenylene sulfide (PPS), Polyethersulfone (PES), polyamide-imide (PAI), Liquid Crystal Polymer (LCP), and polyvinylidene fluoride (PVDF). The special engineering plastic of the present embodiment may be used alone or in combination of two or more of them, and a polymer alloy containing these engineering plastics may be used. As the special engineering plastic used in the present embodiment, a crystalline resin which is easily formed into fine cells is preferable, and among them, polyphenylene sulfide (PPS) and a Liquid Crystal Polymer (LCP) are more preferable.

Polyphenylene Sulfide (PPS) has advantages such as being relatively inexpensive, chemically stable, easily controllable in dimensional accuracy, and high in strength, and thus the demand is increasing mainly for automobile parts. However, PPS has problems in that burrs are likely to be generated during molding, and if it is mixed with long glass fibers or the like, warping is likely to occur, and the specific gravity is large. In the present embodiment, by foam molding PPS, burrs and warpage can be suppressed, and the specific gravity can be further reduced. Since the Liquid Crystal Polymer (LCP) has a large dependency on the shear rate of the molten resin, it is difficult to generate burrs during molding, and high dimensional accuracy can be obtained even in a thin-walled molded part. Among automotive parts, LCP is used in connectors requiring high heat resistance. On the other hand, LCP has problems of high price and large specific gravity. In the present embodiment, by foam molding the LCP, the specific gravity can be reduced, and the amount of use is reduced compared to a solid molded article (non-foamed molded article) of the same size, and therefore, the cost is also reduced.

Various inorganic fillers such as glass fiber, talc, and carbon fiber may be kneaded with the thermoplastic resin of the present embodiment. By mixing an inorganic filler that functions as a foam nucleus agent and an additive that increases melt tension with a thermoplastic resin, it is possible to miniaturize the foam cells. The thermoplastic resin of the present embodiment may contain other various general-purpose additives as necessary.

In the present embodiment, only a special engineering plastic is used as the thermoplastic resin, and a general-purpose thermoplastic resin other than the special engineering plastic may be used in combination depending on the use of the foamed molded article to the extent that the heat resistance of the foamed molded article is not affected. In the present embodiment, the main component of the thermoplastic resin constituting the foamed molded article is the special engineering plastic, and for example, the proportion of the special engineering plastic in the thermoplastic resin constituting the foamed molded article is preferably 60 to 100% by weight, and more preferably 95 to 100% by weight. In the present embodiment, a physical blowing agent is used as the blowing agent, and a chemical blowing agent is not used. Therefore, the special engineering plastic as the thermoplastic resin of the present embodiment does not contain a chemical foaming agent. The melting temperature of special engineering plastics is high, so that it is difficult to use chemical foaming agents together.

In the present embodiment, the thermoplastic resin is plasticized and melted in the plasticizing cylinder 210 having the screw 20 provided therein as shown in fig. 2. The plasticizing cylinder 210 is heated by a belt heater (not shown) provided on the outer wall surface of the plasticizing cylinder 210, and the thermoplastic resin is plasticized and melted by further adding shear heat generated by the rotation of the screw 20.

(2) Pressure maintenance in starvation zone

Next, a physical foaming agent of a fixed pressure is introduced into starvation zone 23 to maintain starvation zone 23 at the fixed pressure (step S2 in fig. 1).

A pressurized fluid is used as the physical blowing agent. The term "fluid" in the present embodiment means any of a liquid, a gas, and a supercritical fluid. In addition, from the viewpoint of cost and environmental load, the physical blowing agent is preferably carbon dioxide, nitrogen gas, or the like. Since the pressure ratio of the physical foaming agent of the present embodiment is low, for example, a fluid that is decompressed to a fixed pressure by a decompression valve from a tank that stores a fluid such as a nitrogen tank, a carbon dioxide tank, or an air tank and is taken out can be used. In this case, since the booster device is not required, the cost of the entire manufacturing apparatus can be reduced. If necessary, a fluid whose pressure is increased to a predetermined pressure may be used as the physical foaming agent. For example, when nitrogen is used as the physical blowing agent, the physical blowing agent can be produced by the following method. First, nitrogen gas is purified by passing through a nitrogen separation membrane while compressing air in the atmosphere by a compressor. Next, the purified nitrogen gas is pressurized to a predetermined pressure using a booster pump, a syringe pump, or the like, to produce a physical blowing agent. In addition, compressed air may also be used as a physical blowing agent. In the present embodiment, the forced shear kneading of the physical blowing agent and the molten resin is not performed. Therefore, even if compressed air is used as the physical blowing agent, oxygen having low solubility in the molten resin is difficult to dissolve in the molten resin, and oxidative degradation of the molten resin can be suppressed.

The pressure of the physical blowing agent introduced in starvation zone 23 is fixed, and the pressure in starvation zone 23 is maintained at the same fixed pressure as the physical blowing agent introduced. The pressure of the foaming agent is, for example, 0.5 to 12MPa, preferably 2 to 12MPa, more preferably 2 to 10MPa, and still more preferably 2 to 8 MPa. The pressure of the physical blowing agent is preferably 1MPa to 6 MPa. The optimum pressure varies depending on the type of the molten resin, and by setting the pressure of the physical blowing agent to 0.5MPa or more, the physical blowing agent in an amount necessary for foaming can be made to permeate into the molten resin, and the foamability of the foamed molded article can be improved. Further, by setting the pressure of the physical foaming agent to 12MPa or less, the heat resistance of the foamed molded article is improved, the occurrence of the swirl marks is suppressed, and the load on the apparatus can be further reduced. The "fixed" pressure of the physical blowing agent for pressurizing the molten resin means that the pressure is preferably within ± 20%, more preferably within ± 10% of a predetermined pressure. The pressure in the starvation zone is measured, for example, by a pressure sensor 27 disposed in the starvation zone 23 of the plasticizing cylinder 210. Further, as the screw 20 advances and retreats, the starvation area 23 moves in the forward and backward directions in the plasticizing cylinder 210, and the pressure sensor 27 shown in fig. 2 is provided at a position existing in the starvation area 23 at all times, out of the foremost position and the rearmost position of the starvation area 23. Further, the position opposite to the introduction port 202 is also always in the starvation area 23. Therefore, although the pressure sensor 27 is not provided at a position facing the introduction port 202, the pressure indicated by the pressure sensor 27 is substantially the same as the pressure at the position facing the introduction port 202. In the present embodiment, only the physical blowing agent is introduced into the starved area 23, and a pressurized fluid other than the physical blowing agent may be simultaneously introduced into the starved area 23 to such an extent that the effect of the present invention is not impaired. In this case, the pressurized fluid containing physical blowing agent introduced into starvation zone 23 has the fixed pressure described above.

In the present embodiment, as shown in fig. 2, the physical foaming agent is supplied from the tank 100 to the starvation area 23 through the inlet 202 via the inlet speed adjusting container 300. The physical blowing agent is depressurized to a predetermined pressure by a pressure reducing valve 151, and then introduced into the starvation zone 23 from the inlet 202 without passing through a pressure increasing device or the like. In the present embodiment, the introduction amount, the introduction time, and the like of the physical blowing agent introduced into the plasticizing cylinder 210 are not controlled. Therefore, a mechanism for controlling these components is not necessary, and for example, a drive valve such as a check valve or a solenoid valve is not necessary, and the introduction port 202 has no drive valve and is always open. In the present embodiment, a fixed physical blowing agent pressure is maintained from the pressure reducing valve 151 through the introduction speed adjustment container 300 to the starvation area 23 in the plasticizing cylinder 210 by the physical blowing agent supplied from the tank 100.

The physical blowing agent inlet port 202 has a larger inner diameter than the physical blowing agent inlet port of the conventional production apparatus. The reason why the inner diameter of the inlet 202 can be increased in this way is that the amount of molten resin in the starved area 23 opposite the inlet 202 during molding is smaller than in the conventional manufacturing apparatus. Therefore, even a physical foaming agent having a low pressure can be efficiently introduced into the plasticizing cylinder 210. Further, even when a part of the molten resin is solidified by being brought into contact with the inlet 202, the inlet can function as a full seal without being completely closed because of the large inner diameter. For example, when the inner diameter of the plasticizing cylinder 210 is large, that is, when the outer diameter of the plasticizing cylinder is large, the inner diameter of the introduction port 202 is easily made large. On the other hand, if the inner diameter of the inlet 202 is excessively large, the molten resin is retained, which causes molding defects, and the introduction speed adjusting container 300 connected to the inlet 202 is increased in size, which increases the cost of the entire apparatus. Specifically, the inner diameter of the introduction port 202 is preferably 20% to 100%, more preferably 30% to 80%, of the inner diameter of the plasticizing cylinder 210. Alternatively, the inner diameter of the introduction port 202 is preferably 3mm to 150mm, more preferably 5mm to 100mm, regardless of the inner diameter of the plasticizing cylinder 210. Here, the inner diameter of the introduction port 202 means the inner diameter of the opening portion in the inner wall 210a of the plasticizing cylinder 210. The shape of the introduction port 202, that is, the shape of the opening in the inner wall 210a of the plasticizing cylinder 210 is not limited to a perfect circle, and may be an ellipse or a polygon. When the shape of the inlet 202 is an ellipse or a polygon, the diameter of a perfect circle having the same area as that of the inlet 202 is defined as "the inner diameter of the inlet 202".

Next, the introduction speed adjustment container 300 connected to the introduction port 202 will be described. The introduction speed adjusting container 300 connected to the introduction port 202 has a volume equal to or larger than a certain value, and thus the flow rate of the physical blowing agent introduced into the plasticizing cylinder 210 is reduced, and a time period during which the physical blowing agent can stay in the introduction speed adjusting container 300 can be secured. The introduction speed adjustment container 300 is directly connected to the plasticizing cylinder 210 heated by a belt heater (not shown) disposed around the plasticizing cylinder, and the heat of the plasticizing cylinder 210 is transferred to the introduction speed adjustment container 300. As a result, the physical blowing agent introduced into the speed adjustment container 300 is heated, the temperature difference between the physical blowing agent and the molten resin is reduced, and the amount of dissolution (amount of penetration) of the physical blowing agent in the molten resin can be stabilized by suppressing an extreme decrease in the temperature of the molten resin in contact with the physical blowing agent. That is, the introduction speed adjusting container 300 functions as a buffer container having a function of heating the physical foaming agent. On the other hand, if the volume of the introduction speed adjustment container 300 is too large, the cost of the entire apparatus increases. The volume of introduction speed adjustment vessel 300 also depends on the amount of molten resin present in starvation zone 23, and is preferably 5mL to 20L, more preferably 10mL to 2L, and still more preferably 10mL to 1L. By setting the volume of the introduction speed adjustment container 300 within this range, the time during which the physical blowing agent can stay can be ensured in consideration of cost.

As will be described later, the physical blowing agent permeates through contact with the molten resin and is consumed in the plasticizing cylinder 210. In order to keep the pressure in starvation zone 23 constant, the amount of physical blowing agent consumed in starvation zone 23 is introduced from introduction speed adjusting vessel 300. If the volume of the introduction speed adjustment container 300 is too small, the frequency of replacement of the physical blowing agent increases, and therefore the temperature of the physical blowing agent becomes unstable, and as a result, the supply of the physical blowing agent may become unstable. Therefore, the introduction speed adjustment container 300 preferably has a volume in which the physical foaming agent consumed in the plasticizing cylinder can be retained in an amount of 1 to 10 minutes. Further, for example, the volume of the introduction speed adjustment vessel 300 is preferably 0.1 to 5 times, more preferably 0.5 to 2 times the volume of the starvation area 23 to which the introduction speed adjustment vessel 300 is connected. In the present embodiment, the volume of the starvation zone 23 means the volume of a region (23) in the empty plasticizing cylinder 210 containing no molten resin, where a portion where the diameter of the shaft of the screw 20 and the depth of the screw flight are constant is located. Further, since the introduction port 202 is always open, the introduction speed adjusting container 300 and the starved area 23 are always kept at a constant pressure of the physical blowing agent during the production of the foamed molded article.

(3) The molten resin is starved

Next, the molten resin is made to flow to the starvation area 23, and the molten resin is made to be in a starved state in the starvation area 23 (step S3 of fig. 1). The starved state is determined by the balance between the amount of molten resin supplied from the upstream side of the starvation zone 23 to the starvation zone 23 and the amount of molten resin supplied from the starvation zone 23 to the downstream side thereof, and if the former is small, the starved state is assumed.

In the present embodiment, the compressing region 22 in which the pressure is increased by compressing the molten resin is provided upstream of the starvation region 23, and the molten resin is starved in the starvation region 23. In the compression zone 22, a large diameter portion 20A is provided in which the diameter of the shaft of the screw 20 is made larger (thicker) than the plasticizing zone 21 located on the upstream side and the screw flight becomes shallower in steps, and further, a seal portion 26 is provided adjacently on the downstream side of the large diameter portion 20A. The seal portion 26 has a large (thick) diameter of the shaft of the screw 20, and is formed with a plurality of shallow grooves instead of the screw flight in the shaft of the screw 20 without providing the screw flight, as in the large diameter portion 20A. The large diameter portion 20A and the seal portion 26 can reduce the gap between the inner wall of the plasticizing cylinder 210 and the screw 20 by increasing the diameter of the shaft of the screw 20, and reduce the amount of resin supplied to the downstream, thereby increasing the flow resistance of the molten resin. Therefore, in the present embodiment, the large diameter portion 20A and the seal portion 26 are means for increasing the flow resistance of the molten resin. Further, the seal portion 26 also achieves the effect of suppressing the backflow of the physical blowing agent, that is, the movement of the physical blowing agent from the downstream side to the upstream side of the seal portion 26.

Due to the presence of the large diameter portion 20A and the seal portion 26, the flow rate of the resin supplied from the compression zone 22 to the starvation zone 23 is reduced, the molten resin is compressed and the pressure is raised in the compression zone 22 on the upstream side, and the molten resin is in an unfilled state (starved state) in the starvation zone 23 on the downstream side. In order to promote the starvation state of the molten resin, the screw 20 has a structure in which the shaft of the portion located in the starvation zone 23 is smaller (thinner) in diameter than the portion located in the compression zone 22 and the screw thread is deep. Further, the screw 20 preferably has a structure in which the shaft of the portion located there throughout the starvation zone 23 has a smaller (thinner) diameter than the portion located in the compression zone 22 and the screw thread is deep. Further, it is preferred that the diameter of the shaft of the screw 20 and the depth of the screw flight be substantially constant throughout the starvation zone 23. This makes it possible to keep the pressure in the starved area 23 substantially constant, thereby stabilizing the starved state of the molten resin. In the present embodiment, as shown in fig. 2, the starvation area 23 is formed in a portion of the screw 20 where the diameter of the shaft of the screw 20 and the depth of the screw flight are fixed.

The mechanism for increasing the flow resistance of the molten resin provided in the compression zone 22 is not particularly limited as long as it is a mechanism for temporarily reducing the flow path area through which the molten resin passes in order to restrict the flow rate of the resin supplied from the compression zone 22 to the starvation zone 23. In the present embodiment, both the large diameter portion 20A of the screw and the seal portion 26 are used, and only one may be used. Examples of the mechanism for increasing the flow resistance other than the large diameter portion 20A and the seal portion 26 of the screw include a structure in which the screw flight is disposed in the opposite direction to the other portions, and a labyrinth structure provided on the screw.

The means for increasing the flow resistance of the molten resin may be provided on the screw as a ring or the like which is a separate member from the screw, or may be provided integrally with the screw as a part of the screw structure. If the mechanism for increasing the flow resistance of the molten resin is provided as a ring or the like which is a member different from the screw, the size of the gap portion which is the molten resin flow path can be changed by changing the ring, and therefore, there is an advantage that the size of the flow resistance of the molten resin can be easily changed.

In addition to the mechanism for increasing the flow resistance of the molten resin, a backflow prevention mechanism (closing mechanism) for preventing the backflow of the molten resin from the upstream compression zone 22 from the starvation zone 23 is provided between the compression zone 22 and the starvation zone 23, whereby the molten resin in the starvation zone 23 can be brought into a starved state. Examples of the closing mechanism include a ring and a steel ball which can be moved upstream by the pressure of the physical blowing agent. However, since the backflow prevention mechanism needs a driving unit, there is a possibility that resin may be accumulated. Therefore, a mechanism for increasing the flow resistance without a driving portion is preferable.

In the present embodiment, the supply amount of the thermoplastic resin to the plasticizing cylinder 210 may be controlled in order to stabilize the starvation state of the molten resin in the starvation zone 23. Because if the supply amount of the thermoplastic resin is excessive, it is difficult to maintain the starved state. In the present embodiment, a general feed screw 212 is used to control the supply amount of the thermoplastic resin. Since the supply amount of the thermoplastic resin is limited, the measurement speed of the molten resin in the starvation region 23 is faster than the plasticizing speed of the compression region 22. As a result, the density of the molten resin in the starved area 23 is stably reduced, and the penetration of the physical blowing agent into the molten resin is promoted.

In the present embodiment, in order to secure the contact area and contact time between the molten resin and the physical blowing agent, it is preferable that the length of the starved area 23 in the flow direction of the molten resin is long, but if it is too long, the molding cycle and the screw length disadvantageously become long. Therefore, the length of the starved zone 23 is preferably 2 to 12 times, more preferably 4 to 10 times the inner diameter of the plasticizing cylinder 210. Furthermore, it is preferred that the length of the starved area 23 covers the entire range of measurement strokes in injection molding. That is, the length of the starved region 23 in the flow direction of the molten resin is preferably equal to or longer than the length of the measurement stroke in the injection molding. By setting the length of the starved area 23 to be equal to or greater than the length of the measurement stroke as the screw 20 moves forward and backward in accordance with the measurement and injection of the plasticization of the molten resin, the introduction port 202 can be always arranged (formed) in the starved area 23 in the production of the foamed molded article. In other words, even if the screw 20 moves forward and backward in the production of the foamed molded article, the region other than the starved area 23 does not enter the position of the inlet 202. Thereby, the physical foaming agent introduced from the introduction port 202 is introduced up to the starved area 23 in the production of the foamed molded article. By providing the starvation zone with a sufficient and appropriate size (length) in this manner, introducing a physical blowing agent of a fixed pressure therein, it is easier to maintain the starvation zone 23 at a fixed pressure. In the present embodiment, as shown in fig. 2, the length of the starvation zone 23 is substantially the same as the diameter of the shaft of the screw 20 and the length of the portion of the screw 20 where the depth of the screw flight is fixed.

Further, a flow rate adjustment zone 25 may be provided between the compression zone 22 and the starvation zone 23. Comparing the flow rate of the molten resin in the compression zone 22 upstream of the flow rate adjustment zone 25 with the flow rate of the molten resin in the starvation zone 23 downstream, the flow rate of the molten resin in the starvation zone 23 is faster. The present inventors have found that the foamability of the foamed molded article to be produced can be improved by providing the flow rate adjusting region 25 as a buffer region between the compression region 22 and the starved region 23 and suppressing such a rapid change (rise) in the flow rate of the molten resin. The reason why the foamability of the foamed molded article is improved by providing the flow rate adjusting region 25 as the buffer region between the compression region 22 and the starved region 23 is not clear in detail, but it is presumed that the following may be one reason: since the molten resin stays in the flow velocity adjusting zone 25, the physical blowing agent and the molten resin flowing from the starvation zone 23 are forcibly kneaded, and the kneading time becomes long. In the present embodiment, the molten resin and the physical blowing agent are decompressed and recompressed by providing a decompression section and a compression section in a portion of the plasticizing screw 20 located in the flow velocity adjusting zone 25 shown in fig. 2 to change the flow path area. Further, the flow rate of the molten resin is adjusted by providing a notch in the screw flight. The decompression section and the compression section can be formed, for example, by changing the depth of the screw flight, in other words, by changing the size (thickness) of the screw diameter.

(4) Contacting molten resin with physical blowing agent

Next, in a state where the starved region 23 is maintained at a fixed pressure, the molten resin in the starved state in the starved region 23 is brought into contact with the physical blowing agent at a fixed pressure (step S4 of fig. 1). That is, in the starvation zone 23, the molten resin is pressurized with a physical blowing agent at a fixed pressure. Since the starved region 23 is a space in which the molten resin is not filled (starved state) and the physical blowing agent can exist, the physical blowing agent can be brought into effective contact with the molten resin. The physical blowing agent in contact with the molten resin permeates into the molten resin and is consumed. If the physical blowing agent is consumed, the physical blowing agent staying in the introduction speed adjustment vessel 300 is supplied to the starvation area 23. Thus, the pressure in starvation zone 23 is maintained at a fixed pressure and the molten resin continues to contact the fixed pressure physical blowing agent.

In conventional foam molding using a physical foaming agent, a predetermined amount of a high-pressure physical foaming agent is forcibly introduced into a plasticizing cylinder for a predetermined time. Therefore, it is necessary to increase the pressure of the physical blowing agent to a high pressure and accurately control the amount, time, and the like of the physical blowing agent introduced into the molten resin, and the physical blowing agent is brought into contact with the molten resin for only a short introduction time. In the present embodiment, however, the physical blowing agent is not forcibly introduced into the plasticizing cylinder 210, but the physical blowing agent of a fixed pressure is continuously supplied into the plasticizing cylinder so that the pressure in the starved area 23 is fixed, and the physical blowing agent is continuously brought into contact with the molten resin. This stabilizes the amount of physical blowing agent dissolved (permeated) in the molten resin, which is determined by the temperature and pressure. In addition, since the physical blowing agent of the present embodiment is always in contact with the molten resin, a necessary and sufficient amount of the physical blowing agent can be permeated into the molten resin. Thus, the foamed molded article produced in the present embodiment has fine foam cells even when a low-pressure physical blowing agent is used, as compared with a conventional molding method using a physical blowing agent.

In addition, in the manufacturing method of the present embodiment, since it is not necessary to control the introduction amount, the introduction time, and the like of the physical foaming agent, a drive valve such as a check valve or an electromagnetic valve is not necessary, and further, a control mechanism for controlling them is not necessary, and the apparatus cost is reduced. Further, the physical blowing agent used in the present embodiment is also lower in pressure than a conventional physical blowing agent, and therefore the burden on the apparatus is also small.

In the present embodiment, in the production of a foamed molded article in which the injection molding cycle is continuously performed, the starved region 23 is kept at a constant pressure. That is, in order to replenish the physical foaming agent consumed in the plasticizing cylinder, the entire steps of the method for producing a foamed molded article are performed while continuously supplying the physical foaming agent at a fixed pressure. In the present embodiment, for example, in the case of injection molding in which multiple injections are continuously performed, a subsequent injection amount of molten resin is prepared in the plasticizing cylinder during the injection step, the cooling step of the molded body, and the removing step of the molded body, and the subsequent injection amount of molten resin is pressurized at a fixed pressure by the physical foaming agent. That is, in injection molding in which multiple injections are continuously performed, 1 cycle of injection molding including a plasticization measurement step, an injection step, a cooling step of a molded body, a take-out step, and the like is performed in a state where a molten resin in a plasticizing cylinder is always in contact with a physical foaming agent at a fixed pressure, that is, in a state where the molten resin in the plasticizing cylinder is always pressurized at a fixed pressure by the physical foaming agent. Similarly, in the case of continuous molding such as extrusion molding, molding is performed in a state where the molten resin in the plasticizing cylinder is always in contact with a physical blowing agent at a fixed pressure, that is, in a state where the molten resin in the plasticizing cylinder is always pressurized by the physical blowing agent at a fixed pressure.

(5) Foam molding

Next, the molten resin in contact with the physical foaming agent is molded into a foamed molded article (step S5 of fig. 1). The plasticizing cylinder 210 used in the present embodiment has a recompression zone 24, which is disposed downstream of the starvation zone 23, is adjacent to the starvation zone 23, and raises the pressure of the compressed molten resin. First, the molten resin in the starvation zone 23 is made to flow to the recompression zone 24 by the rotation of the plasticizing screw 20. The molten resin containing the physical blowing agent is pressure-regulated in the recompression zone 24, extruded ahead of the plasticizing screw 20, and measured. At this time, the internal pressure of the molten resin extruded forward of the plasticizing screw 20 is controlled by a hydraulic motor or an electric motor (not shown) connected to the rear of the plasticizing screw 20 as a screw back pressure. In the present embodiment, in order to uniformly compatibilize the physical blowing agent without separating it from the molten resin and stabilize the resin density, it is preferable to control the internal pressure of the molten resin extruded forward of the plasticizing screw 20 (i.e., the screw back pressure) to be about 1 to 6MPa higher than the pressure of the starvation zone 23 which is kept constant. In the present embodiment, a check ring 50 is provided at the tip of the screw 20 so that the compressed resin in front of the screw 20 does not flow backward to the upstream side. Thus, the pressure in starvation zone 23 does not affect the resin pressure ahead of screw 20 when measured.

The method for molding the foamed molded article is not particularly limited, and the molded article can be molded by, for example, injection foam molding, extrusion foam molding, foam blow molding, or the like. In the present embodiment, the measured molten resin is injected and filled from the plasticizing cylinder 210 shown in fig. 2 into a cavity (not shown) in the mold, and injection foam molding is performed. As the injection foam molding, a short shot method of filling a cavity with a molten resin having a filling capacity of 75% to 95% of the cavity volume of the mold and filling the cavity while expanding bubbles may be used, or a core-removing method of expanding and foaming the cavity volume after filling the molten resin having a filling amount of 100% of the cavity volume of the mold may be used. Since the resulting foamed molded article has cells inside, shrinkage of the thermoplastic resin during cooling is suppressed, and a molded article having a low specific gravity is obtained with reduced sink marks and warpage. The shape of the foamed molded article is not particularly limited. The resin composition may be in the form of a sheet or a tube obtained by extrusion molding, a complicated shape obtained by injection molding, or the like.

In the method for producing a foamed molded article described above, since it is not necessary to control the amount of introduction, the introduction time, and the like of the physical foaming agent into the molten resin, a complicated control device can be omitted or simplified, and the device cost can be reduced. In the method for producing a foamed molded article of the present embodiment, the molten resin in a starved state is brought into contact with the physical foaming agent at a constant pressure in the starved area 23 while the starved area 23 is kept at the constant pressure. This can stabilize the amount of physical blowing agent dissolved (permeated) in the molten resin by a simple mechanism.

(6) Forming of circuit patterns

Next, a circuit pattern is formed on the surface of the obtained foam molded product (step S6 in fig. 1). The method for forming the circuit pattern on the foam molded product is not particularly limited, and a general method, for example, a plating film may be used. For example, a method of forming a plating film on the surface of a foam molded body, patterning the formed plating film with a photoresist, and removing the plating film except for the circuit pattern by etching is exemplified. In addition, a method of irradiating a portion of the foamed molded article where a circuit pattern is to be formed with laser light to roughen the surface or to provide a functional group thereto, and forming a plating film only on the laser-irradiated portion may be used. The circuit pattern may be formed by the methods disclosed in japanese patent application laid-open nos. 2017 and 31441 and 2017 and 160518.

A method for forming a circuit pattern used in the present embodiment will be described below with reference to fig. 3 and 4. First, the catalyst activity suppression layer 61 is formed on the surface of the foamed molded article 60 (step S11 in fig. 3 and fig. 4 (a)). Next, a part of the surface of the foamed molded article on which the catalyst activity suppression layer 61 is formed, that is, a part where a circuit pattern is formed, is heated or irradiated with light (step S12 of fig. 3). In this embodiment, laser drawing is performed on a portion where a circuit pattern is formed. The laser-irradiated portion 60a is heated, and the catalyst activity suppression layer 61 of the heated portion is removed (fig. 4 (b)). An electroless plating catalyst is applied to the surface of the laser-drawn foam molding 60 (step S13 in fig. 3), and then the foam molding is brought into contact with the electroless plating solution (step S14 in fig. 3). In this method, the catalyst activity suppressing layer 61 suppresses (hinders) the catalyst activity of the electroless plating catalyst imparted thereto. Therefore, the generation of the electroless plating film is suppressed on the catalytic activity suppression layer 61. On the other hand, the laser drawing portion 60a generates the electroless plating film 62 due to the removal of the catalyst activity suppressing layer 61. By the above-described method, a molded circuit member 600 in which a circuit pattern formed of the electroless plating film 62 is formed on the surface of the foam molded body 60 is obtained (fig. 4 (c)).

The catalyst activity suppression layer preferably contains a polymer having at least one of an amide group and an amino group (hereinafter, appropriately referred to as "amide group-containing/amino group-containing polymer"), for example. The amide group-containing/amino group-containing polymer functions as a catalyst activity inhibitor that inhibits (hinders) or reduces the catalyst activity of the electroless plating catalyst. The mechanism by which the amide group-containing/amino group-containing polymer suppresses the catalytic activity of the electroless plating catalyst is not yet determined, and it is presumed that the amide group and the amino group are adsorbed, coordinated, reacted, and the like with the electroless plating catalyst, and thus the electroless plating catalyst cannot function as a catalyst.

The amide group-containing/amino group-containing polymer may be any optional one, and from the viewpoint of suppressing the catalytic activity of the electroless plating catalyst, a polymer having an amide group is preferable, and a branched polymer having a side chain is preferable. In the branched polymer, the side chain preferably contains at least one of an amide group and an amino group, and more preferably contains an amide group. The branched polymer is preferably a dendrimer. Dendrimers are polymers composed of a molecular structure of frequently regularly repeating branched chains, and are classified into dendrimers and hyperbranched polymers. The dendrimer is a spherical polymer having a structure of a complete tree-like branch chain with a strict regularity centered on a molecule serving as a core and a diameter of several nm, and the hyperbranched polymer is a polymer having incomplete tree-like branch chains, unlike the dendrimer having a complete tree-like structure. Among dendrimers, hyperbranched polymers are relatively easy to synthesize and inexpensive, and are therefore preferred as the branched polymer of the present embodiment.

The laser, the electroless plating catalyst and the electroless plating solution used in the laser drawing are not particularly limited, and a general-purpose substance can be appropriately selected and used. In the formation of the circuit pattern, another type of electroless plating film or electroplating film may be further laminated on the electroless plating film. The plating film 62 for forming the circuit pattern may be formed in a planar shape on only one surface of the foamed molded body 60, or may be formed three-dimensionally along a plurality of surfaces of the foamed molded body 60 or a three-dimensional surface including a spherical surface. When the plating film 62 is formed three-dimensionally along a plurality of surfaces of the foam molded body 60 or along a three-dimensional surface including a spherical surface or the like, the plating film 62 functions as a three-dimensional electric circuit, and the molded circuit component 600 having the plating film 62 of such a predetermined pattern functions as a three-dimensional circuit molded component (MID).

Further, as shown in fig. 4(c), the molded circuit member 600 manufactured by the present embodiment described above has the catalyst activity suppression layer 61, but the present embodiment is not limited thereto. The production method of the present embodiment may further include a step of removing the catalyst activity suppressing layer 61 from the surface of the foamed molded article 60. As a method for removing the catalyst activity suppressing layer 61 from the molded foam 60, there is a method in which the molded foam 60 is washed with a washing liquid to dissolve the amide group/amino group-containing polymer in the washing liquid and remove the amide group/amino group-containing polymer. The washing liquid is not particularly limited as long as it dissolves the amide group-containing/amino group-containing polymer and does not change the properties of the foamed molded article 60, and it can be appropriately selected according to the material of the foamed molded article 60 and the kind of the amide group-containing/amino group-containing polymer.

< molded circuit component >

The molded circuit member 600 of the present embodiment includes a base material as the foamed molded body 60 containing the thermoplastic resin and a circuit pattern formed on the base material, and is lightweight. The present inventors have also found that a molded circuit component having high heat resistance can be produced by the production method of the present embodiment. The heat-resistant temperature of the special engineering plastic used in the manufacturing method of the embodiment is as high as 150 ℃. However, a general foam molded product has lower heat resistance than a solid molded product (non-foam molded product), and a foam molded product produced using a conventional high-pressure physical foaming agent cannot obtain sufficient heat resistance even when a special engineering plastic is used as a thermoplastic resin. In a conventional molded circuit part using a foamed molded article of a special engineering plastic, there are disadvantages such as expansion of foam cells and increase in thickness of the molded article if the molded article is passed through a reflow furnace. On the other hand, when the molded circuit member obtained in the present embodiment is heated and the surface temperature of the molded circuit member is maintained at 240 to 260 ℃ for 5 minutes, the rate of change in the thickness of the molded circuit member due to heating is-2 to 2%, preferably-1 to 1%. In addition, when the surface temperature of the molded circuit member obtained in the present embodiment is maintained at 200 to 260 ℃ for 3 to 10 minutes, for example, the rate of change in the thickness of the molded circuit member due to heating is-2 to 2%, preferably-1 to 1%. Such a molded circuit component having high heat resistance has a small change in shape even when it is passed through a reflow furnace for lead-free solder, and is less likely to cause swelling or the like.

Here, the "rate of change in thickness of the molded circuit member due to heating" is defined by the following equation. The molded circuit component may be heated in a reflow furnace, for example.

(Da－Db)/Db×100(％)

Db: thickness of molded circuit parts before heating

Da: thickness of molded circuit parts after heating

It is presumed that the high heat resistance of the molded circuit component of the present embodiment is brought about by using a special engineering plastic as the thermoplastic resin and setting the fixed pressure of the physical blowing agent in contact with the starved molten resin to a specific range of, for example, 0.5MPa to 12 MPa. In conventional foam molding using a supercritical fluid or the like, a high-pressure physical foaming agent having an average pressure of 15 to 20MPa is used. The manufacturing method of the present embodiment is different from the conventional foam molding in that a physical blowing agent of a relatively low pressure and a fixed pressure is brought into contact with a molten resin. The present inventors have found that the heat resistance of a foamed molded article is improved by setting the fixing pressure of the physical blowing agent to, for example, 12MPa or less, preferably 10MPa or less, more preferably 8MPa or less, and still more preferably 6MPa or less. Further, by reducing the fixing pressure of the physical blowing agent, appearance defects (spin marks) can be improved. The lower limit of the fixed pressure of the physical blowing agent is 0.5MPa or more, preferably 1MPa or more, and more preferably 2MPa or more, from the viewpoint of allowing the physical blowing agent in an amount necessary for foaming to permeate into the molten resin.

The mechanism by which the molded circuit component of the present embodiment has high heat resistance is not clear, and there is a possibility that: the molded circuit component of the present embodiment is different from a conventional foamed molded article in the fine structural change, for example, a very microscopic structural change, by the combination of a specific type of thermoplastic resin (a special engineering plastic) and a fixed pressure (for example, 0.5MPa to 12MPa) of a physical foaming agent in a specific range. Further, it is presumed that the residual foaming agent in the foamed molded article expands by heating, and adversely affects the heat resistance of the foamed molded article. Therefore, it is considered that the reason why the foamed molded article of the present embodiment has high heat resistance is simply because the amount of the residual foaming agent in the foamed molded article is small. However, according to the studies of the inventors, it was found that even if the residual foaming agent is degassed to some extent from the conventional foamed molded article by, for example, annealing treatment or the like, the same heat resistance as that of the foamed molded article of the present embodiment cannot be obtained, and swelling or the like is generated by heating. Therefore, it is presumed that the amount of the residual blowing agent is not a factor of the high heat resistance of the foamed molded article of the present embodiment. The above-described examination is merely an assumption by the inventors based on a phenomenon observed at present, and is not intended to limit the scope of the present invention at all.

The fixed pressure of the physical foaming agent in the present embodiment is, for example, 0.5MPa to 12MPa, and there is a more preferable range depending on the kind of the special engineering plastic. For example, when the special engineering plastic is polyphenylene sulfide (PPS), the fixing pressure of the physical foaming agent is preferably 2MPa to 12MPa, more preferably 2MPa to 10MPa, and still more preferably 2MPa to 8 MPa. When the special engineering plastic is a Liquid Crystal Polymer (LCP), the fixing pressure of the physical foaming agent is preferably 1MPa to 6 MPa. When the type of the special engineering plastic and the fixing pressure of the physical foaming agent are in the above-mentioned combination, a foamed molded article having a better foamability and a higher heat resistance can be obtained, and further, the occurrence of swirl marks can be suppressed.

The average cell diameter of the foamed cells contained in the molded circuit component produced in the present embodiment is preferably 100 μm or less, and more preferably 50 μm or less. When the average cell diameter of the cells to be foamed is within the above range, the side walls of the cells are small, and therefore expansion is difficult during heating, and as a result, the heat resistance of the foamed molded article is further improved. The average cell diameter of the foamed cells can be determined by, for example, SEM photograph image analysis of a cross section of the foamed molded article.

In the foamed molded article for molding a circuit member produced in the present embodiment, the thickness of the foamed part in which the foamed cells are formed is preferably 0.5mm or more, more preferably 1mm or more, and still more preferably 2mm or more. When the thickness is within the above range, a skin-like layer having a sufficient thickness can be formed in the molded article. The expansion of the foam cells during heating of the molded circuit component can be suppressed by the skin layer, and therefore the heat resistance of the molded circuit component is further improved. In particular, when LCP is used as a special engineering plastic, it is difficult for encapsulated gas containing a physical foaming agent to be released from a foamed molded article of LCP. By increasing the thickness of the foamed part, expansion of the foamed cells due to expansion of the encapsulated gas is suppressed, and the heat resistance of the molded circuit component using LCP is further improved. In the foam molded body of the molded circuit member produced in the present embodiment, the thickness of the foamed part in which the foamed cells are formed may be 3mm or less, 2mm or less, or 1mm or less. Although the smaller the thickness of the foamed part, the greater the rate of change in the thickness of the molded circuit member by heating tends to be, the molded circuit member produced by the production method of the present embodiment has high heat resistance, and therefore, the rate of change in the thickness of the molded circuit member by heating can be suppressed to-2% to 2%, preferably-1% to 1%, even in a foamed part having a thickness within the above range.

In this embodiment, the foam molded body may be further subjected to annealing treatment before the circuit pattern is formed. By heating the foamed molded article in the annealing treatment, the entrapped gas containing the physical foaming agent can be degassed from the foamed molded article. This suppresses expansion of the foam cells due to expansion of the encapsulated gas, thereby further improving the heat resistance of the molded circuit component.

[ second embodiment ]

< Circuit component >

In this embodiment, a circuit member 700 shown in fig. 5(a), (b), and 6 will be described. The circuit member 700 of the present embodiment includes a base material 10 which is a foamed molded body containing a thermoplastic resin, and a circuit pattern 70 formed on the base material 10, and is lightweight. Further, the circuit member 700 has: a substrate 10 having a mounting surface 10a and a back surface 10b opposite to the mounting surface 10a, a circuit pattern 70 formed on the surface of the substrate 10 including the mounting surface 10a, and a mounting member 30 mounted on the mounting surface 10a of the substrate 10 and electrically connected to the circuit pattern 70, which is a plate-like foamed molded article having a density reduction rate of preferably 0.5% to 10%.

The substrate 10 contains a thermoplastic resin, preferably a thermoplastic resin and an insulating heat conductive filler, and has foamed cells 11 inside.

The thermoplastic resin is preferably a high-melting-point thermoplastic resin having heat resistance and solder reflow resistance. For example, aromatic polyamides such as 6T nylon (6TPA), 9T nylon (9TPA), 10T nylon (10TPA), 12T nylon (12TPA), MXD6 nylon (MXDPA), and alloy materials thereof, polyphenylene sulfide (PPS), Liquid Crystal Polymer (LCP), polyether ether ketone (PEEK), polyether imide (PEI), and polyphenylene sulfone (PPSU) can be used. Among them, polyphenylene sulfide is preferred as the thermoplastic resin of the present embodiment because it is inexpensive among so-called super engineering plastics (special engineering plastics). These thermoplastic resins may be used alone, or 2 or more kinds may be used in combination. In the present embodiment, the mounting member 30 is mounted by soldering. Therefore, the thermoplastic resin used for the base material 10 preferably has a melting point of 260 ℃ or higher, more preferably 290 ℃ or higher, so that soldering can be performed. The case of using low-temperature solder for mounting the mounting member 30 is not limited to the above.

The insulating heat conductive filler is a filler having a heat conductivity of 1W/m.K or more, except for a conductive heat releasing material such as carbon. Examples of the insulating heat conductive filler include ceramic powders such as alumina, silica, magnesia, magnesium hydroxide, boron nitride, and aluminum nitride, which are high heat conductive inorganic powders. In order to increase the contact ratio between the fillers and improve the thermal conductivity, a rod-like filler such as wollastonite or a plate-like filler such as talc or boron nitride may be mixed. The insulating heat conductive filler is contained in the base material 10 by, for example, 10 to 90 wt%, preferably 30 to 80 wt%. If the amount of the insulating heat conductive filler is within the above range, the circuit component 700 of the present embodiment can obtain sufficient heat dissipation.

Further, in order to control the strength, the substrate 10 may contain a rod-like or needle-like filler such as glass fiber or calcium titanate. The base material 10 may contain various general-purpose additives added to the resin molded body as necessary.

The base material 10 is a foamed molded article having a density reduction ratio of preferably 0.5% to 10%. The density reduction rate of the substrate 10 is more preferably 1% to 7%, and still more preferably 4% to 6%. When the density reduction rate of the substrate 10 is set within the above range, the moldability of the substrate 10 is improved, and the circuit member 700 can obtain sufficient heat dissipation. Here, the density decrease rate of the foamed molded article is a ratio of a difference between the density of the solid molded article and the density of the foamed molded article to the density of a non-foamed molded article (solid molded article) molded using the same material as the foamed molded article. The foamed molded article contains foamed cells (cells), and therefore has a smaller specific gravity than a solid molded article. For example, a density reduction rate of the foamed molded article of 5% means that the density (95%) of the foamed molded article is reduced by 5% with respect to the density (100%) of the solid molded article.

The circuit pattern 70 is formed on the resin base 10 as an insulator, and is preferably formed by electroless plating. Therefore, the circuit pattern 70 may include electroless nickel-phosphorus film, electroless copper film, electroless nickel film, and other electroless plated films, and preferably includes electroless nickel-phosphorus film. The circuit pattern 70 may be formed by further laminating another type of electroless plating film or electroplating film on the electroless plating film on the resin substrate 10. The resistance of the circuit pattern 70 can be reduced by increasing the total thickness of the plating film. The circuit pattern 70 preferably includes an electroless copper plating film, an electrolytic nickel plating film, or the like, from the viewpoint of reducing the resistance. In addition, a plating film of gold, silver, tin, or the like may be formed on the outermost surface of the circuit pattern 70 in order to improve the solder wettability of the plating film.

When a gold plating film is provided on the outermost surface of the circuit pattern 70, the wettability of the solder is improved and the circuit pattern can be prevented from being corroded. However, if the gold plating film is provided on the entire outermost surface of the circuit pattern 70, the cost increases. In order to suppress the cost increase and prevent the corrosion of the circuit pattern 70, a portion of the mounting surface 10a other than the mounting portion 12 of the soldered mounting member 30 may be covered with a resist, and a gold plating film may be formed only on the outermost surface of the circuit pattern formed on the mounting portion 12. In the mounting portion 12, the gold plating film improves the wettability of the solder, suppresses the corrosion of the circuit pattern, and suppresses the corrosion of the circuit pattern 70 in the portion other than the mounting portion 12 by the inexpensive resist.

The mounting component 30 is electrically connected to the circuit pattern 70 by solder 31, and generates heat by energization to serve as a heat source. Examples of the mounting member 30 include an LED (light emitting diode), a power module, an IC (integrated circuit), and a thermal resistor. In the present embodiment, an LED is used as the mounting member 30. The mounting member 30 is mounted on the mounting surface 10a of the base 10. The circuit pattern 70 is formed on the surface of the base material 10 including the mounting surface 10a so as to be electrically connected to the mounting member 30.

In the portion (mounting portion 12) of the base material 10 where the mounting member 30 is mounted, the distance from the mounting surface 10a to the rear surface 10b (the thickness d of the mounting portion 12) is preferably 0.1mm or more, and more preferably more than 0.5 mm. Here, the distance from the mounting surface 10a to the rear surface 10b (the thickness d of the mounting portion 12) is a distance in the direction of the perpendicular m to the mounting surface 10a from the mounting surface 10a to the rear surface 10b of the mounting portion 12. When the thickness d of the mounting portion 12 is not constant, the thickness d preferably varies within the above range. In the present embodiment, the substrate 10 is a plate-like body, and the back surface 10b is a surface opposite to the mounting surface 10 a. Since the substrate 10 of the present embodiment is a plate-like body having a constant thickness, the thickness d is also the thickness of the substrate 10.

The thickness d is preferably small in order to dissipate heat generated by the mounting member 30 from the rear surface 10 b. However, if the thickness d of the mounting portion 12 is too thin, the flowability of the resin in the mounting portion 12 is reduced when the base material 10 is molded, and as a result, moldability is reduced. In addition, the mechanical strength of the substrate 10 is reduced, and the substrate 10 alone is difficult to be self-supporting. When the substrate 10 cannot be self-supported, for example, a support member such as a metal plate for supporting the substrate 10 must be added to the back surface 10b of the substrate 10, which increases the cost. In the present embodiment, the mounting portion 12 has an appropriate thickness, so that the formability and mechanical strength of the base material 10 can be prevented from being reduced, and a support member for the base material 10 is not necessary, so that an increase in cost can be prevented. When importance is attached to the mechanical strength of the base material 10, the thickness d is preferably 0.6mm or more. The upper limit of the thickness d is not particularly limited, and may be appropriately determined according to the use of the circuit member 700. From the viewpoint of cost, the thickness d is, for example, 2.5mm or less.

In addition, generally, if the thickness of the foam molded article is 0.2mm or less or 0.5mm or less, the foam molded article is mainly composed of a skin layer, and the core layer is hardly formed inside, and as a result, it is difficult to form foam cells inside. If the thickness d of the mounting portion 12 is 0.2mm or less or 0.5mm or less, almost no foam cells are present inside, and thus the heat radiation property to the back surface 10b is improved. On the other hand, if the thickness d of the mounting portion 12 exceeds 0.5mm, the foam cells 11 may be present inside the mounting portion 12, and thus the heat dissipation tends to be reduced. However, since the substrate 10 of the present embodiment contains the insulating heat conductive filler, it is possible to ensure a certain level of heat radiation property, and it is also advantageous to improve mechanical strength as described above.

As described below, the circuit component 700 of the present embodiment described above can achieve both mass productivity and heat dissipation. The substrate 10 is a foamed molded body. Therefore, even in the case of a thermoplastic resin containing an insulating heat conductive filler, the fluidity of the molten resin is improved by the foaming agent contained during molding. Further, the foaming pressure improves the transferability of the mold, and the substrate 10 obtains sufficient dimensional accuracy. In this way, since the moldability of the base material 10 is improved, molding is performed without increasing the holding pressure or the clamping pressure, and the generation of burrs is suppressed. This can suppress the manufacturing cost of the circuit member 700 and improve mass productivity. On the other hand, since the foamed molded article contains foamed cells, the heat insulating property tends to be improved and the heat releasing property tends to be lowered. However, in the substrate 10 of the present embodiment, the density decrease rate is determined to be within the relatively low range, and as shown in fig. 6, the generation of bubbles in the skin layer 13 can be suppressed. The foamed cells 11 are present primarily within the core layer 14. Therefore, the surface of the substrate 10 (mounting surface 10a) to which the mounting member 30 serving as a heat source is mounted has little influence on the foam cells 11, and the insulating heat conductive filler is oriented in the resin flow direction, thereby obtaining sufficient heat dissipation properties.

Further, the base material 10 of the present embodiment is a foam molded body, and has solder reflow resistance. Since the foamed molded article contains foam cells, the surface is likely to bulge when solder is reflowed. However, by setting the density decrease rate of the base material 10 within the above relatively low range, the density of the foam cells 11 in the base material 10 can be made relatively low. Further, the amount of the foaming agent remaining in the resin can be reduced. This presumably improves the solder reflow resistance of the substrate 10. Further, in the base material 10 of the present embodiment, the amount of the foaming agent to be used can be reduced by setting the density decrease rate to be within the above-described relatively low range. For example, in the case of using a physical blowing agent as the blowing agent, a physical blowing agent having a relatively low pressure may be used. This makes it difficult for the circuit pattern 70 to have a poor appearance during foam molding, and therefore, the circuit pattern 70 is easily formed on the surface. Further, in the circuit component 700 of the present embodiment, since the base material 10 has sufficient heat radiation performance, a metal heat radiation member may not be provided. Thereby enabling cost reduction.

In the present embodiment, as shown in fig. 5(a), (b) and 6, the circuit pattern 70 is formed only on one surface (mounting surface 10a) of the base 10 of the plate-like body, but the present embodiment is not limited thereto. The substrate 10 is not limited to a plate-like body, and may have any shape according to the use of the circuit member 700. The circuit pattern 70 may be formed three-dimensionally along a three-dimensional surface including a spherical surface or the like, continuously over a plurality of surfaces of the base material 10. When the circuit pattern 70 is formed three-dimensionally along a three-dimensional surface including a spherical surface or the like over a plurality of surfaces of the base material 10, the circuit member 700 functions as a three-dimensional molded circuit member.

In the circuit component 700 of the present embodiment, when the thermoplastic resin is a special engineering plastic, the heat resistance thereof may be equivalent to the heat resistance of the molded circuit component 600 (see fig. 4(c)) of the first embodiment. That is, when the circuit member 700 is heated and the surface temperature of the circuit member 700 is maintained at 240 to 260 ℃ for 5 minutes, the rate of change in the thickness of the circuit member 700 due to heating may be-2% to 2%, or preferably-1% to 1%. In the circuit member 700 obtained in the present embodiment, when the surface temperature of the circuit member 700 is maintained at 200 to 260 ℃ for 3 to 10 minutes, for example, the rate of change in the thickness of the circuit member 700 due to heating may be-2 to 2%, and preferably-1 to 1%. The circuit component having such high heat resistance has a small change in shape even when it passes through a reflow furnace for lead-free solder, and is less likely to bulge.

< method for manufacturing circuit component >

A method of manufacturing the circuit member 700 will be described. First, a thermoplastic resin preferably containing an insulating heat conductive filler is foam-molded to obtain a foam-molded article (substrate 10) having a density reduction ratio of preferably 0.5% to 10%. The base material 10 is preferably formed by foaming using a physical foaming agent such as carbon dioxide or nitrogen. The foaming agent includes a chemical foaming agent and a physical foaming agent, but the chemical foaming agent has a low decomposition temperature and thus it is difficult to foam a resin material having a high melting point. The base material 10 is preferably made of a resin having a high melting point and high heat resistance. If a physical foaming agent is used, the base material 10 can be foam-molded using a high-melting resin. As a molding method using a physical blowing agent, MuCell (registered trademark) using a supercritical fluid, a low-pressure foaming molding method which does not require high-pressure equipment and which is proposed by the present inventors (for example, described in WO 2017/007032) can be used.

When the base material 10 is molded by the low-pressure foam molding method described in WO2017/007032, the density reduction rate of the foam molded article can be adjusted by adjusting the pressure of the physical foaming agent introduced into the plasticizing cylinder of the foam injection molding machine, the filling rate of the resin in the mold, and the like. In the low-pressure foam molding method, the pressure of the physical foaming agent introduced into the plasticizing cylinder is, for example, 10MPa or less, preferably 6MPa or less, and more preferably 2MPa or less.

The base material 10 can be produced by the same production method as the foamed molded article 60 of the first embodiment, using the production apparatus (injection molding apparatus) 1000 shown in fig. 2 used in the first embodiment.

Next, a circuit pattern 70 is formed on the surface of the base 10 including the mounting surface 10 a. The method for forming the circuit pattern 70 is not particularly limited, and a general method can be used. Examples thereof include: a method of forming a plating film on the mounting surface 10a as a whole, patterning the plating film with a photoresist, and removing the plating film except for the circuit pattern by etching, a method of irradiating a laser beam to the portion where the circuit pattern is to be formed to roughen the substrate, and forming a plating film only on the laser-irradiated portion, and the like. The circuit pattern 70 may be formed by the same method as that of the circuit pattern of the first embodiment.

In the present embodiment, the circuit pattern 70 is formed by the method described below. First, a catalytic activity suppression layer is formed on the surface of the substrate 10. Next, a laser drawing is performed on the electroless plating film-formed portion of the mounting surface 10a of the substrate 10 on which the catalytic activity suppression layer is formed, that is, the circuit pattern 70 is formed. Thereby, the laser drawing portion 15 is formed on the mounting surface 10a (fig. 7(a) and (b)). The laser-mapped surface of the substrate 10 is given an electroless plating catalyst and, subsequently, is brought into contact with an electroless plating solution. The catalyst activity inhibiting layer inhibits (hinders) the catalyst activity imparted to the electroless plating catalyst thereon. Therefore, the generation of the electroless plating film is suppressed on the catalyst activity suppression layer. On the other hand, the laser drawing portion 15 generates an electroless plating film due to the removal of the catalyst activity suppressing layer. Thereby, in the laser drawing portion 15, a circuit pattern 70 is formed by electroless plating (fig. 8(a) and (b)).

The catalyst activity suppressing layer may be formed using a resin (catalyst deactivator) that suppresses the catalytic activity. As the catalyst deactivator, a polymer having an amide group and a dithiocarbamate group in a side chain is preferable. It is presumed that the amide group and the dithiocarbamate group of the side chain act on the metal ion as the electroless plating catalyst to suppress the exertion of the catalytic ability. The catalyst deactivator is preferably a dendrimer such as a dendrimer or a hyperbranched polymer. As the catalyst deactivator, for example, a polymer disclosed in Japanese patent laid-open publication No. 2017-160518 can be used, and a suppression layer can be formed on the surface of the substrate by the method disclosed in the same patent publication.

The laser and the laser drawing method used in the laser drawing are not particularly limited, and a general laser and a laser drawing method can be appropriately selected and used. In the laser drawing portion 15, as shown in fig. 7(b), the surface of the substrate 10 may be roughened while the catalyst activity suppression layer (not shown in the figure) is removed. Thereby, the electroless plating catalyst is easily adsorbed to the laser drawing portion 15.

The electroless plating catalyst is not particularly limited, and a general-purpose material can be appropriately selected and used. Further, as the electroless plating catalyst, for example, a plating catalyst solution containing a metal salt such as palladium chloride disclosed in japanese patent application laid-open No. 2017-036486 can be used. In the case where a plating catalyst solution containing a metal salt is used as an electroless plating catalyst, a pretreatment liquid that promotes adsorption of an electroless plating catalyst may be applied to a substrate before applying the plating catalyst solution to the substrate. As the pretreatment liquid, for example, an aqueous solution containing a nitrogen-containing polymer such as polyethyleneimine can be used.

The electroless plating solution and the electroless plating method are not particularly limited, and a general electroless plating solution and an electroless plating method can be appropriately selected and used. The electroless plating solution contains a reducing agent such as sodium hypophosphite or formalin, for example. As the electroless plating solution, an electroless nickel-phosphorus plating solution, an electroless copper plating solution, an electroless palladium plating solution, and the like can be used, and among them, sodium hypophosphite containing an electroless plating catalyst (metal ion) and having a good reduction effect is preferably used as a reducing agent, and the plating solution is a stable electroless nickel plating solution (electroless nickel-phosphorus plating solution). In the formation of the circuit pattern 70, another type of electroless plating film or electroplating film may be further laminated on the electroless plating film.

As described above, in order to suppress the increase in cost and prevent corrosion of the circuit pattern 70, the mounting surface 10a may be covered with a resist except for the mounting portion 12 of the soldered mounting component 30, and a gold plating film may be formed only on the outermost surface of the circuit pattern 70 formed on the mounting portion 12. The circuit pattern of such a manner can be formed by, for example, the following method. First, a solder resist (for example, manufactured by sun ink corporation) is applied to the entire surface of the substrate 10 on which the circuit pattern is formed, excluding the gold plating film on the outermost surface, including the mounting surface 10a, to form a resist layer. Next, the resist layer on the mounting surface 10a of the mounting portion 12 is removed by laser light to form an opening, and the circuit pattern is exposed in the opening. Further, a gold plating film is formed only on the outermost surface of the circuit pattern exposed in the opening.

After the circuit pattern 70 is formed on the substrate 10, the mounting member 30 is mounted on the mounting surface 10a of the substrate 10 and electrically connected to the circuit pattern 70. This results in the circuit component 700 of the present embodiment. The mounting method is not particularly limited, and a general method can be used, and for example, the mounting member 30 can be soldered to the base material 10 by a solder reflow method in which the base material 10 on which the mounting member 30 is disposed is passed through a high-temperature reflow furnace, or a laser soldering method (spot mounting) in which the interface between the base material 10 and the mounting member 30 is irradiated with a laser beam to perform soldering.

[ modification 1]

Next, a modified example 1 of the second embodiment shown in fig. 9 will be described. The substrate 10 of the circuit member 700 shown in fig. 5 is a plate-like body having a constant thickness, but the present embodiment is not limited thereto. For example, as in the circuit component 400 of the present modification shown in fig. 9, the recess 45 defined by the side wall 45a and the bottom surface 45b may be provided on the back surface 40b of the base 40. The mounting member 30 is mounted on the mounting surface 40a corresponding to the bottom surface 45 b. The circuit component 400 of the present modification has the same configuration as the circuit component 700 shown in fig. 5, except for the recess 45.

In the present modification, the recess 45 is provided in the back surface 40b, and the thickness d1 of the mounting portion 42 provided with the mounting member 30 is reduced, whereby the core layer in the mounting portion 42 is made thin. This improves the heat conductivity in the thickness direction of the mounting portion 42, and facilitates the release of heat generated by the mounting member 30 to the rear surface 40 b. This can further improve the heat dissipation of the circuit component 400.

As a method of reducing the thickness d1 of the mounting portion 42, a method of providing a recess in the mounting surface 40a may be considered. However, if the mounting surface 40a is provided with irregularities, there is a possibility that it is difficult to form the circuit pattern 70. For example, in the case of forming a pattern of an electroless plating film using the above-described catalytic activity suppressing layer, there is a case where the contrast (contrast) of the plating film is hard to adhere to the surface having irregularities. In the present modification, by providing the rear surface 40b with the irregularities, the heat dissipation performance of the circuit member 400 can be improved without adversely affecting the formation of the circuit pattern 70 on the mounting surface 40 a.

The distance d1 from the mounting surface 40a to the bottom surface 45b is preferably 0.1mm to 1.5mm, for example. Here, the distance d1 from the mounting surface 40a to the bottom surface 45b is a distance in the perpendicular direction of the mounting surface 40a from the mounting surface 40a to the bottom surface 45 b. When the distance d1 is not fixed, the distance d1 preferably varies within the above range. By setting the distance d1 within the above range, the moldability and mechanical strength of the base material 40 can be prevented from being lowered, and the heat dissipation performance of the circuit member 400 can be improved.

In the present modification, as shown in fig. 9, 1 mounting member 30 is mounted on the mounting surface 40a corresponding to the bottom surface 45b of 1 recess 45. However, the present embodiment is not limited thereto. For example, a plurality of mounting members 30 may be mounted on the mounting surface 40a corresponding to the bottom surface 45b of 1 recess 45. The area of the bottom surface 45b may be larger or smaller than the area of the bottom surface of the mounting member 30, or the area of the bottom surface 45b may be substantially the same as the area of the bottom surface of the mounting member 30.

The area of the bottom surface 45b of each mounting member 30 arranged on the mounting surface 40a corresponding to the bottom surface 45b is, for example, 4cm²Hereinafter, preferably 0.4cm²～4cm². The larger the area of the bottom surface 45b, the higher the heat radiation property, but the moldability and mechanical strength of the recess 45 are lowered. By setting the area of the bottom surface 45b within the above range, heat radiation property, moldability, and mechanical strength can be both satisfied.

The thickness d2 of the portion of the base material 40 other than the mounting portion 42 is, for example, 0.6mm to 2.5mm from the viewpoint of mechanical strength and cost.

The recess 45 may be formed simultaneously with the molding of the substrate 40. For example, the base material 40 of the present modification can be molded using a mold having a convex portion corresponding to the concave portion 45 in a mold cavity.

[ modification 2]

Next, a modified example 2 of the second embodiment shown in fig. 10 will be described. As shown in fig. 10, in the circuit component 500 of the present modification, a recess 55 defined by a side wall 55a and a bottom surface 55b is provided on the back surface 50b of the base material 51. Further, a through hole 56 is formed from the mounting surface 50a of the mounting portion 52 to which the mounting member 30 is mounted toward the bottom surface 55b, and an electroless plating film 71 is formed on the inner wall of the through hole 56. The through-hole 56 of the present modification is filled with an electroless plating film 71. The electroless plated film 71 of the through hole 56 is connected to the mounting component 30 via the circuit pattern 70 and the solder 31. The circuit component 500 of the present modification has the same configuration as the circuit component 400 shown in fig. 9 except for the through hole 56.

In this modification, by providing the through hole 56 filled with the electroless plating film 71 inside, the heat generated in the mounting member 30 is easily released to the rear surface 50b through the electroless plating film 71. This can further improve the heat dissipation performance of the circuit component 500. Further, by forming the electroless plating film 71 inside the through hole 56, it is possible to suppress a decrease in mechanical strength of the mounting portion 52 in which the through hole 56 is formed.

The through hole 56 may also be formed by laser processing, for example. The electroless plated film 71 inside the through hole 56 may be formed simultaneously when the circuit pattern 70 is formed by the electroless plated film, for example.

In the present modification, the through hole 56 is provided, but the present embodiment is not limited thereto, and the hole provided in the mounting surface 50a does not necessarily have to penetrate to the bottom surface 55 b. That is, a non-through hole may be provided instead of the through hole 56, and for example, a recess may be formed from the mounting surface 50a to the bottom surface 55b of the mounting portion 52, and an electroless plating film may be formed on the surface of the recess. The through hole is preferable because the electroless plating solution can be more easily flowed by the through hole from the viewpoint of forming the electroless plating film. On the other hand, from the viewpoint of mechanical strength of the mounting portion 52 and prevention of corrosion of the electroless plating film formed therein, a recess portion in which the hole provided in the mounting surface 50a does not penetrate to the bottom surface 55b is more preferable. The concave portion can also achieve an effect of improving heat radiation of the circuit part 500. The depth of the recess from the mounting surface 50a to the bottom surface 55b of the mounting portion 52 may be arbitrarily determined as long as it is deeper than the thickness of the electroless plating film for forming the circuit pattern. The recess is not limited to a hole extending in a direction perpendicular to the mounting surface 50a, and may be a groove extending in the mounting surface 50 a.