阅读说明：本技术 带金属层的碳质构件及导热板 (Carbonaceous member with metal layer and heat conductive plate ) 是由 喜多晃一 长瀬敏之 中矢清隆 岩田广太郎 于 2019-10-31 设计创作，主要内容包括：一种碳质构件(21),其包含由单层或多层的石墨烯堆积而成的石墨烯聚集体及扁平状的石墨颗粒,所述碳质构件的结构为扁平状的所述石墨颗粒以其基底面叠摞的方式将所述石墨烯聚集体作为粘合剂而层叠,并使扁平状的所述石墨颗粒的基底面朝一个方向取向。金属层(25)具备金属镀层(26),所述金属镀层(26)直接形成于在碳质构件(21)中层叠的所述石墨颗粒的边缘面所面对的表面(边缘层叠面),金属镀层(26)以导热系数为50W/(m·K)以上的金属构成。(A carbonaceous member (21) comprising a graphene aggregate formed by stacking single-layer or multi-layer graphene and flat graphite particles, wherein the carbonaceous member has a structure in which the flat graphite particles are stacked with the graphene aggregate as a binder so that their basal surfaces are stacked, and the basal surfaces of the flat graphite particles are oriented in one direction. The metal layer (25) is provided with a metal plating layer (26), the metal plating layer (26) is directly formed on the surface (edge lamination surface) facing the edge surface of the graphite particles laminated in the carbonaceous member (21), and the metal plating layer (26) is made of a metal having a thermal conductivity of 50W/(m.K) or more.)

1. A carbonaceous member with a metal layer, comprising a carbonaceous member and a metal layer formed on at least a part of the surface of the carbonaceous member, characterized in that the carbonaceous member with a metal layer,

the carbonaceous member includes a graphene aggregate formed by stacking a single layer or a plurality of layers of graphene, and flat graphite particles, the carbonaceous member has a structure in which the flat graphite particles are stacked with the graphene aggregate as a binder so that their basal planes are stacked, and the basal planes of the flat graphite particles are oriented in one direction,

the metal layer is provided with a metal plating layer formed directly on an edge-laminated surface facing an edge surface of the graphite particles laminated in the carbonaceous member,

the metal plating layer is made of a metal having a thermal conductivity of 50W/(mK) or more.

2. The metallized carbonaceous member according to claim 1, wherein,

the metal layer includes the metal plating layer and a metal member layer composed of a metal member bonded to the metal plating layer.

3. The metallized carbonaceous member according to claim 2, wherein,

a bonding layer composed of a metal calcined body is formed between the metal plating layer and the metal member layer.

4. The carbonaceous member with a metal layer according to any one of claims 1 to 3, wherein,

the arithmetic average height Sa of the edge laminated surface is 1.1 [ mu ] m or more, and the maximum height Sz of the edge laminated surface is 20 [ mu ] m or more.

5. A heat-conducting plate for diffusing heat emitted from a heating element mounted on a main surface in a planar direction and conducting the heat in a thickness direction,

the carbonaceous member with a metal layer according to any one of claims 1 to 4,

the carbonaceous member is disposed such that the basal surface of the graphite particle extends in the thickness direction, and the metal plating layer is formed on the main surface facing an edge surface of the graphite particle.

Technical Field

The present invention relates to a carbonaceous member with a metal layer which is particularly suitable as a heat conductive member, for example, capable of efficiently transferring heat emitted from a heat generating element, and a heat conductive sheet comprising the carbonaceous member with a metal layer.

The present application claims priority based on patent application No. 2018-206000 of japanese application at 31/10/2018, and the contents thereof are incorporated herein.

Background

In various devices on which heating elements (power semiconductor elements and LED elements) are mounted, such as power modules and LED modules, for example, heat sinks are provided for efficiently dissipating heat generated in the heating elements, and heat conductive plates disclosed in patent documents 1 to 3, for example, are sometimes disposed between the heating elements (elements and substrates on which the elements are mounted) and the heat sinks.

Patent document 1 discloses a power module including an insulating plate and a surface conductor composed of a plate-like two-dimensional superconductive material provided on a main surface of the insulating plate. The two-dimensional superconductor has a structure in which single-layer graphene is stacked in multiple layers in the growth axis direction, and has excellent thermal conductivity in a plane orthogonal to the growth axis direction. In patent document 1, after titanium is vapor-deposited on the surface of the two-dimensional superconductive material, a Ni — P plating layer is formed.

Patent document 2 discloses an anisotropic heat transfer element having a structure of graphene sheets laminated along a plane intersecting a plane in contact with a heat source, and a support member covering a peripheral edge portion of the structure. A titanium layer to be an active material is formed on the surfaces of the structure and the supporting member, and a nickel layer or a copper layer is formed thereon. In patent document 2, "PYROID HT" (trade name) manufactured by MINTEQ International inc.

Patent document 3 discloses an anisotropic heat transfer element including a structure in which graphene sheets are laminated in a 1 st direction and an intermediate member bonded to an end face of the structure in a 2 nd direction intersecting the 1 st direction, wherein the intermediate member is pressure-bonded to the end face through an insertion material containing at least titanium. In patent document 3, "PYROID HI" (trade name) manufactured by MINTEQ International Inc. is used as a structural body.

Patent document 1: japanese patent No. 6299407

Patent document 2: japanese patent laid-open publication No. 2011-023670

Patent document 3: japanese patent laid-open publication No. 2012 and 238733

In the above patent documents 1 to 3, a metal layer is formed on the surface of a carbonaceous member for protecting the carbonaceous member on which graphene is laminated or improving the bondability to other members.

In the above patent documents 1 to 3, when a metal layer is formed on the surface of a carbonaceous member on which graphene is laminated, a titanium layer is formed on the surface of the carbonaceous member, and a nickel layer or a copper layer is formed on the titanium layer. That is, the titanium layer as the active metal is interposed between the carbonaceous member and the metal layer, thereby securing the bonding strength.

However, since titanium has a relatively low thermal conductivity of 17W/(m · K), the titanium layer interposed between the carbonaceous member and the metal layer becomes thermal resistance, and even if the basal plane of the carbonaceous member disposed as graphene extends in the thickness direction of the heat conductive plate, there is a possibility that heat cannot be efficiently transferred in the thickness direction.

Disclosure of Invention

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a carbonaceous member with a metal layer, which can firmly bond a metal layer to a carbonaceous member and can efficiently conduct heat, and a heat conductive sheet using the carbonaceous member with a metal layer.

The carbonaceous member with a metal layer according to an aspect of the present invention includes a carbonaceous member and a metal layer formed on at least a part of a surface of the carbonaceous member, and is characterized in that the carbonaceous member includes a graphene aggregate formed by stacking a single layer or a plurality of layers of graphene and flat graphite particles, the graphite particles having a structure in which the flat graphite particles are stacked with the graphene aggregate as a binder so that base surfaces thereof are stacked, and the base surfaces of the flat graphite particles are oriented in one direction, the metal layer includes a metal plating layer formed directly on a surface (referred to as an edge stacking surface) facing an edge surface of the graphite particles stacked on the carbonaceous member, and the metal plating layer is made of a metal having a thermal conductivity of 50W/(m · K) or more.

In the carbonaceous member with a metal layer, appropriate irregularities are formed on the surface (referred to as edge-laminated surface) facing the edge surfaces of the graphite particles, the metal layer includes a metal plating layer formed on the surface (edge-laminated surface) facing the edge surfaces of the graphite particles laminated, and the plating metal constituting the metal plating layer sufficiently penetrates into the irregularities existing on the surface layer portion of the carbonaceous member, thereby improving the bonding strength between the metal plating layer and the carbonaceous member. Therefore, it is not necessary to interpose titanium or the like as an active metal between the carbonaceous member and the metal layer.

Further, since the metal plating layer is made of a metal having a thermal conductivity of 50W/(m · K) or more, the thermal resistance of the metal plating layer is not large. Therefore, the heat emitted from the heat generating element disposed on the metal layer can be efficiently conducted to the carbonaceous member side through the metal layer.

In the carbonaceous member with a metal layer according to this aspect, the metal layer preferably includes the metal plating layer and a metal member layer composed of a metal member bonded to the metal plating layer. In this case, since the metal layer includes the metal plating layer and the metal member layer, the thickness of the metal layer can be ensured by the metal member layer, heat can be sufficiently diffused along the metal layer, and heat conduction characteristics can be further improved. Since the metal plating layer and the metal member layer are bonded to each other by metal, sufficient bonding strength can be ensured.

In the carbonaceous member with a metal layer according to this embodiment, a bonding layer made of a calcined metal body is preferably formed between the metal plating layer and the metal member layer. In this case, since the bonding layer formed between the metal plating layer and the metal member layer is formed of a metal calcined body, thermal stress generated when the carbonaceous member with a metal layer is subjected to thermal cycles, which is caused by a difference in thermal expansion coefficient between the carbonaceous member and the metal member layer, can be relaxed in the bonding layer, and thus damage to the carbonaceous member with a metal layer can be suppressed.

In the carbonaceous member with a metal layer according to this embodiment, the arithmetic mean height Sa of the edge stacking surface is preferably 1.1 μm or more, and the maximum height Sz of the edge stacking surface is preferably 20 μm or more. When these ranges are satisfied, the metal plating layer is more strongly bonded to the irregularities of the edge lamination surface, and therefore the bonding strength between the metal plating layer and the carbonaceous member can be further improved. The arithmetic average height Sa represents an average of absolute values of differences in height of points on the measurement plane with respect to the average plane of the heights of the measurement area plane. The maximum height Sz represents the distance from the highest point to the lowest point of the surface of the measurement area plane.

More preferably, the arithmetic average height Sa of the edge laminated surface is 1.1 μm or more and 5 μm or less, and the maximum height Sz of the edge laminated surface is 20 μm or more and 50 μm or less. More preferably, the arithmetic mean height Sa of the edge laminated surface is 1.1 μm or more and 3.0 μm or less, and the maximum height Sz of the edge laminated surface is 20 μm or more and 40 μm or less. The reference plane when the arithmetic average height Sa and the maximum height Sz of the edge laminated surface are measured may be, for example, 3.02mm × 3.02 mm. Further, the arithmetic average height Sa and the maximum height Sz may be measured by a method of converting interference fringe brightness information obtained by a white light interference microscope into height information.

In the carbonaceous member with a metal layer of this embodiment, the edge lamination surface may be roughened by a roughening treatment such as an ozone treatment in advance in order to set the arithmetic average height Sa and the maximum height Sz of the edge lamination surface within predetermined ranges. After the ozone treatment of the edge laminated surface, the metal plating layer is more firmly bonded to the unevenness of the edge laminated surface roughened by the ozone treatment, and therefore, the bonding strength between the metal plating layer and the carbonaceous member can be further improved.

In the heat conductive plate according to another aspect of the present invention, the heat generated by the heating element mounted on the main surface is diffused in the planar direction and conducted in the thickness direction, and the heat conductive plate is composed of the carbonaceous member with the metal layer, the carbonaceous member is disposed such that the basal surface of the graphite particles extends in the thickness direction of the carbonaceous member, and the metal plating layer is formed on the main surface of the carbonaceous member facing the edge surface of the graphite particles.

According to the heat transfer plate, since the heat transfer plate is composed of the carbonaceous member with the metal layer, and the carbonaceous member is arranged such that the basal plane of the graphite particles extends in the thickness direction of the carbonaceous member, the heat transfer coefficient in the thickness direction of the carbonaceous member increases. Further, since the metal plating layer is formed on the main surface of the carbonaceous member facing the edge surface of the graphite particle, the heat emitted from the heating element mounted on the main surface can be efficiently diffused in the surface direction of the metal layer having the metal plating layer, and the heat can be efficiently conducted in the thickness direction. The metal plating layer is formed of a metal having a thermal conductivity of 50W/(m.K) or more and is formed on the main surface facing the edge surface of the graphite particle, and therefore, the metal plating layer does not become a thermal resistance and can efficiently conduct heat in the thickness direction.

According to the present invention, a carbonaceous member with a metal layer and a heat conductive sheet using the carbonaceous member with a metal layer can be provided, in which a metal layer is firmly bonded to a carbonaceous member and heat can be efficiently conducted.

Drawings

Fig. 1 is a schematic explanatory view of a power module using a heat-conducting plate (carbonaceous member with a metal layer) according to an embodiment of the present invention.

Fig. 2 is a schematic explanatory view of a heat-conducting plate (carbonaceous member with a metal layer) according to an embodiment of the present invention.

Fig. 3 is an observation result of a bonding interface between the carbonaceous member and the metal plating layer of the heat conductive plate (carbonaceous member with metal layer) according to the embodiment of the present invention.

Fig. 4 is a schematic view of a bonding interface between the carbonaceous member and the metal plating layer of the heat conductive plate (carbonaceous member with metal layer) according to the embodiment of the present invention.

Fig. 5 is a flowchart showing a method for manufacturing a heat-conducting plate (carbonaceous member with a metal layer) according to an embodiment of the present invention.

Fig. 6 is a schematic explanatory view of a heat-conducting plate (carbonaceous member with a metal layer) according to another embodiment of the present invention.

Fig. 7 is a schematic explanatory view of another power module using the heat conductive plate (carbonaceous member with metal layer) according to the embodiment of the present invention.

Fig. 8 is a schematic explanatory view of another power module using the heat conductive plate (carbonaceous member with metal layer) according to the embodiment of the present invention.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings. With respect to the embodiments shown below, the present invention is not limited unless otherwise specified. In the drawings used in the following description, important parts may be shown enlarged for convenience in order to facilitate understanding of the features of the present invention, and the dimensional ratios of the respective constituent elements and the like are not necessarily the same as those in reality.

First, a power module using a heat conductive plate (carbonaceous member with a metal layer) as an embodiment of the present invention will be described with reference to fig. 1 to 5.

The power module 1 shown in fig. 1 includes: an insulated circuit board 10, a semiconductor element 3 bonded to one surface side (upper side in fig. 1) of the insulated circuit board 10 by a solder layer 2, a heat conductive plate 20 disposed on the other surface side (lower side in fig. 1) of the insulated circuit board 10, and a heat sink 30 disposed on the other surface side of the heat conductive plate 20.

The insulated circuit board 10 includes: an insulating layer 11, a circuit layer 12 disposed on one surface (upper surface in fig. 1) of the insulating layer 11, and a heat transfer layer 13 disposed on the other surface (lower surface in fig. 1) of the insulating layer 11.

The insulating layer 11 is used to prevent electrical connection between the circuit layer 12 and the heat transfer layer 13, and in the present embodiment, is made of highly insulating aluminum nitride (AlN)) Alumina (Al)₂O₃) Silicon nitride (Si)₃N₄) And the like. The thickness of the insulating layer 11 is set to be in the range of 0.2 to 1.5mm, and may be set to be 0.635mm in the present embodiment.

The circuit layer 12 is formed by bonding a metal plate having excellent conductivity to one surface of the insulating layer 11. In the present embodiment, as the metal plate constituting the circuit layer 12, a copper plate made of copper or a copper alloy, specifically, a rolled plate of oxygen-free copper is used. A circuit pattern is formed on the circuit layer 12, and one surface (upper surface in fig. 1) thereof serves as a mounting surface on which the semiconductor element 3 is mounted.

The thickness of the metal plate (copper plate) to be the circuit layer 12 is set to be in the range of 0.1mm to 1.0mm, and may be set to be 0.6mm in the present embodiment.

The heat transfer layer 13 is formed by bonding a metal plate having excellent thermal conductivity to the other surface of the insulating layer 11. In the present embodiment, as the metal plate constituting the heat transfer layer 13, a copper plate made of copper or a copper alloy, specifically, a rolled plate of oxygen-free copper is used.

The thickness of the metal plate (copper plate) to be the heat transfer layer 13 is set to be in the range of 0.1mm to 1.0mm, and may be set to be 0.6mm in the present embodiment.

The insulating layer 11 made of ceramic and the copper plate to be the circuit layer 12 and the heat transfer layer 13 can be joined by a brazing method using an active metal, a DBC method, or the like.

The heat sink 30 is used for cooling the insulating circuit board 10, and has a structure in which a plurality of flow paths 31 for flowing a cooling medium (for example, cooling water) are provided.

The heat sink 30 is preferably made of a material having good thermal conductivity, for example, aluminum or an aluminum alloy, copper or a copper alloy, and may be made of oxygen-free copper in the present embodiment.

The semiconductor element 3 is made of a semiconductor material such as Si or SiC. The semiconductor element 3 is mounted on the circuit layer 12 via a solder layer 2 made of, for example, a Sn — Ag based, Sn-In based, or Sn-Ag-Cu based solder.

The heat transfer plate 20 of the present embodiment is interposed between the insulating circuit board 10 and the heat sink 30. As described later, the outermost layers of both main surfaces of the heat transfer plate 20 are made of oxygen-free copper, and the heat transfer layer 13 and the heat sink 30 of the insulating circuit board 10 made of copper are joined by solder layers 6 and 8 made of, for example, Sn-Ag based, Sn-In based, or Sn-Ag-Cu based solders, as shown In FIG. 1.

As shown in fig. 2, the heat transfer plate 20 of the present embodiment includes: a plate body 21 made of a carbonaceous member, and metal layers 25 formed on both main surfaces (edge-laminated surfaces) of the plate body 21. The carbonaceous member constituting the plate main body 21 includes a graphene aggregate formed by stacking single-layer or multi-layer graphene and flat graphite particles, and the graphite particles having a flat structure are stacked with the graphene aggregate as a binder so that their basal surfaces are stacked.

As shown in fig. 4, the flat graphite particles have a basal surface presenting a carbon hexagonal mesh surface and an edge surface presenting an end portion of the carbon hexagonal mesh surface. As the flat graphite particles, flake graphite, scale graphite, soil graphite, flake graphite, condensed graphite, pyrolytic graphite, highly oriented pyrolytic graphite, and the like can be used. The average particle diameter observed from the basal plane of the graphite particles is preferably in the range of 10 μm or more and 1000 μm or less, more preferably in the range of 50 μm or more and 800 μm or less, as measured by a line segment method, for example. The average particle diameter of the graphite particles is set within the above range, whereby the thermal conductivity is improved.

The average thickness of the graphite particles is preferably in the range of 1 μm or more and 50 μm or less, and more preferably in the range of 1 μm or more and 20 μm or less, when measured by a line segment method, for example. By setting the thickness of the graphite particles within the above range, the orientation of the graphite particles is appropriately adjusted.

By setting the thickness of the graphite particles within the range of 1/1000-1/2 of the particle diameter observed from the basal plane, excellent thermal conductivity and orientation of the graphite particles are properly adjusted. The thickness of the graphite particles is more preferably in the range of 1/1000 to 1/500 of the particle diameter as viewed from the basal plane.

The graphene aggregate is formed by stacking single-layer or multi-layer graphene, and the number of layers of multi-layer graphene is, for example, 100 layers or less, preferably 50 layers or less. The graphene aggregate can be produced, for example, as follows: a graphene dispersion liquid obtained by dispersing single-layer or multi-layer graphene in a solvent containing a lower alcohol or water is dropped on a filter paper, and the solvent is separated and accumulated.

The average particle size of the graphene aggregate is preferably in the range of 1 μm or more and 1000 μm or less, for example, when measured by a line segment method. By setting the average particle diameter of the graphene aggregate within the above range, the thermal conductivity can be improved. The average particle diameter of the graphene aggregate is more preferably 50 μm or more and 800 μm or less.

The thickness of the graphene aggregate is preferably in the range of 0.05 μm or more and less than 50 μm, for example, when measured by a line segment method. By setting the thickness of the graphene aggregate within the above range, the strength of the carbonaceous member can be ensured. The thickness of the graphene aggregate is more preferably 1 μm or more and 20 μm or less.

In the present embodiment, the carbonaceous members constituting the plate main body 21 are arranged such that the basal plane of the stacked graphite particles extends in the thickness direction of the plate main body 21. Therefore, as shown in fig. 4, the edge surfaces of the graphite particles are made to face the main surface (edge laminated surface) of the plate main body 21. In this way, the edge surfaces of the graphite particles face the main surface of the plate body 21, thereby forming irregularities on the main surface (edge laminated surface) of the plate body 21. Since the projections and recesses of the main surface (edge-laminated surface) of the plate body 21 have a U-shaped cross section with a pair of substantially parallel surfaces, the metal layer 25 enters the projections and recesses to obtain a high anchoring effect, thereby improving the bonding strength between the edge-laminated surface 21 and the metal layer 25. In order to reliably form the uneven portions of the edge lamination surface, ozone treatment can be performed to increase the surface roughness.

The metal layer 25 of this embodiment includes: a metal plating layer 26 directly formed on the main surface of the plate body 21, a metal member layer 27 composed of a metal member bonded to the metal plating layer 26, and a bonding layer 28 formed between the metal member layer 27 and the metal plating layer 26. In the present invention, the metal layer 25 may be a single layer. The metal plating layer 26 is made of a metal having a thermal conductivity of 50W/(m · K) or more, specifically, a pure metal such as Ni, Cu, Ag, Sn, and Co, or an alloy containing these metals as a main component. These elements have a higher thermal conductivity than titanium. In the present embodiment, the metal plating layer 26 may be an Ag plating layer made of pure silver.

The thermal conductivity of the metal constituting the metal plating layer 26 is more preferably 100W/(m · K) or more. Further, the metal constituting the metal plating layer 26 preferably has a thermal conductivity of 200W/(m · K) or more.

The thickness of the metal plating layer 26 is preferably in the range of 0.1 μm to 500 μm, and more preferably in the range of 1 μm to 300 μm. The thickness of the metal plating layer 26 is more preferably 0.5 μm or more and 100 μm or less.

The metal member constituting the metal member layer 27 is preferably made of a metal having excellent thermal conductivity, and the metal member of the present embodiment may be a rolled sheet of oxygen-free copper, for example.

The thickness of the metal member layer 27 (thickness of the metal member) is preferably in the range of 30 μm to 5000 μm, and more preferably in the range of 50 μm to 3000 μm.

The bonding layer 28 formed between the metal plating layer 26 and the metal member layer 27 is made of a metal calcined body, and in the present embodiment, is a calcined body of silver paste containing silver particles or silver oxide particles.

The density of the bonding layer 28 is preferably in the range of 60% to 90%, and more preferably in the range of 70% to 80%, as measured by observing an SEM image, for example. By setting the porosity of the bonding layer 28 within the above range, thermal stress generated when thermal cycles are loaded can be relaxed in the bonding layer 28.

Next, fig. 3 shows an observation photograph of the bonding interface between the plate main body 21 and the metal plating layer 26 according to the present embodiment, and fig. 4 shows a schematic view of the bonding interface between the plate main body 21 and the metal plating layer 26.

In fig. 3, the lower black portion is a plate main body 21 (carbonaceous member), and the upper gray portion thereof is a metal plating layer 26 (e.g., Ag plating layer).

In the present embodiment, as shown in fig. 3 and 4, the edge surface of the graphite particle is made to face the main surface of the plate body 21, thereby forming irregularities on the main surface of the plate body 21, and the plating metal (Ag in the present embodiment) of the metal plating layer 26 penetrates into the plate body 21 side in accordance with the irregularities. Thereby, the metal plating layer 26 and the plate main body 21 are firmly joined by an action commonly referred to as an anchor effect.

Next, a method for producing the heat conductive plate 20 (carbonaceous member with a metal layer) according to the present embodiment will be described with reference to a flowchart shown in fig. 5.

(plate body Forming Process S01)

First, the flat graphite particles and the graphene aggregate are weighed in a predetermined mixing ratio and mixed by a conventional mixing device such as a ball mill.

The obtained mixture was filled in a mold having a predetermined shape and pressurized to obtain a molded article. Heating may be performed during pressurization.

The obtained molded body is subjected to a cutting process to obtain a plate main body 21. At this time, the cutting is performed such that the basal surface of the flat graphite particles extends in the thickness direction of the plate body 21 and the edge surface of the flat graphite particles faces the main surface of the plate body 21.

The pressure at the time of molding is not limited, but is preferably set in the range of 20MPa to 1000MPa, and more preferably in the range of 100MPa to 300 MPa. The temperature at the time of molding is not limited, but is preferably set in the range of 50 ℃ to 300 ℃. The pressing time is not limited, but is preferably in the range of 0.5 minutes to 10 minutes.

The arithmetic average height Sa of the edge laminated surface is 1.1 μm or more, and the maximum height Sz of the edge laminated surface is preferably 20 μm or more. When this range is satisfied, the metal plating layer is more strongly bonded to the irregularities of the edge lamination surface, and therefore the bonding strength between the metal plating layer and the carbonaceous member can be further improved.

More preferably, the arithmetic average height Sa of the edge laminated surface is 1.1 μm or more and 5 μm or less, and the maximum height Sz of the edge laminated surface is 20 μm or more and 40 μm or less. More preferably, the arithmetic mean height Sa of the edge laminated surface is 1.1 μm or more and 3 μm or less, and the maximum height Sz of the edge laminated surface is 20 μm or more and 40 μm or less. The reference plane for measuring the arithmetic average height Sa and the maximum height Sz of the edge laminated surface may be, for example, 3.02mm × 3.02 mm. Also, the arithmetic average height Sa and the maximum height Sz can be measured using a method of converting interference fringe brightness information obtained by a white light interference microscope into height information.

In order to set the arithmetic average height Sa and the maximum height Sz of the edge laminated surface within the predetermined ranges, the edge laminated surface may be roughened by ozone treatment in advance. After the ozone treatment is performed on the edge laminated surface, the metal plating layer is more firmly bonded to the unevenness of the edge laminated surface formed by the ozone treatment, and therefore, the bonding strength between the metal plating layer and the carbonaceous member can be further improved.

The conditions of the ozone treatment for roughening the edge lamination surface are, for example, as follows.

The edge laminated surface was subjected to ozone treatment by irradiating ultraviolet rays for 30 minutes with an ozone cleaning apparatus (model UV312, TECHVISION gmbh) equipped with a low-pressure mercury lamp.

In order to roughen the edge laminated surface, Plasma treatment may be used instead of ozone treatment, and as an example of conditions in this case, the graphene may be irradiated with O by a Plasma treatment apparatus (Plasma Dry Cleaner "PDC-210" (trade name) manufactured by yamat science corporation)₂Plasma, and a method of performing plasma processing.

(Metal plating layer formation step S02)

Next, metal plating layers 26 are formed on both main surfaces of the plate body 21. The plating method is not particularly limited, and a wet plating method such as an electrolytic plating method or an electroless plating method can be used. In this embodiment, the Ag plating layer can be formed by an electrolytic plating method.

Before plating, a pretreatment such as a plasma treatment or an oxidation treatment may be performed on the main surface (edge lamination surface) of the plate body 21. By performing the pretreatment, the roughness of the edge lamination surface can be controlled.

The plating conditions in the metal plating layer forming step S02 are not limited, but the current density of the electrolytic plating is set to 0.1A/dm²Above and 10A/dm²Preferably in the range of 1A/dm²Above and 3A/dm²Within the following ranges.

The plating solution is not limited, but a conventional Ag cyanide plating solution may be used, and an additive may be used as appropriate. For example, a plating solution containing silver cyanide (AgCN) in a range of 30 to 50g/L and potassium cyanide (KCN) in a range of 100 to 150g/L can be used.

As described above, the edge surfaces of the graphite particles having the appropriate orientation are made to face the main surface (edge-laminated surface) of the plate body 21 to form irregularities, and the metal in the plating solution enters the irregularities, so that the plating metal of the metal plating layer 26 penetrates into the plate body 21 side, thereby firmly bonding the plate body 21 and the metal plating layer 26.

(Metal Member layer Forming Process S03)

Next, a metal member is bonded to the surface of the metal plating layer 26 to form a metal member layer 27. In the present embodiment, silver paste containing silver powder or silver oxide powder is applied to the surface of the metal plating layer 16. The silver paste is made to contain silver powder and a solvent. A resin or a dispersant may be contained as required. Instead of silver powder, silver oxide powder and a reducing agent may be contained.

The average particle diameter of the silver powder and the silver oxide powder is preferably within a range of 10nm to 10 μm, and more preferably within a range of 100nm to 1 μm. The coating thickness of the silver paste is preferably set in the range of 10 μm to 100 μm, and more preferably 30 μm to 50 μm.

After the silver paste was coated as described above, rolled sheets of oxygen-free copper as metal members were laminated. Next, the rolled sheet of oxygen-free copper as the metal member and the sheet main body 21 on which the metal plating layer 26 is formed are pressed and heated in the lamination direction, and the silver paste is fired, thereby joining the metal member and the metal plating layer 26.

The pressing load during the pressing is not limited, but is preferably set in the range of 5MPa or more and 30MPa or less, and the heating temperature is preferably set in the range of 150 ℃ or more and 280 ℃ or less. In the present embodiment, although not limited, it is preferable that the holding time of the heating temperature is set to be in the range of 3 minutes to 20 minutes, and the atmosphere is a non-oxidizing atmosphere.

A bonding layer 28 composed of a calcined silver is formed between the metal member layer 27 and the metal plating layer 26, and the porosity of the bonding layer 28 is set to be, for example, 70% to 80% by defining bonding conditions as described above.

Through the above steps, the heat conductive plate 20 (carbonaceous member with a metal layer) of the present embodiment is manufactured.

According to the heat conductive plate 20 (carbonaceous member with metal layer) of the present embodiment, the carbonaceous member constituting the plate main body 21 includes a graphene aggregate formed by stacking a single layer or a plurality of layers of graphene and flat graphite particles, the structure of the carbonaceous member is such that the flat graphite particles are stacked with the graphene aggregate as a binder so that their basal planes are stacked, and the basal planes of the graphite particles are arranged to extend in the thickness direction of the plate main body, so that the thermal conductivity in the thickness direction in the plate main body 21 (carbonaceous member) increases.

The graphite particles have edge surfaces facing the main surface of the plate body 21, thereby forming irregularities.

Since the metal plating layer 26 is formed on the main surface (edge lamination surface) of the plate main body 21 on which the irregularities are formed, as shown in fig. 3, the plating metal of the metal plating layer 26 sufficiently penetrates into the plate main body 21 (carbonaceous member), and the metal plating layer 26 and the plate main body 21 (carbonaceous member) are firmly bonded by the anchoring action of the roughened surface.

The metal plating layer 26 is made of a metal having a thermal conductivity of 50W/(m · K) or more, specifically, a pure metal such as Ni, Cu, Ag, Sn, and Co, or an alloy containing these metals as a main component, and in the present embodiment, the thermal resistance of the metal plating layer 26 is not large because of the Ag plating layer.

Therefore, the heat emitted from the heat generating element (the insulating circuit board 10 on which the semiconductor element 3 is mounted) mounted on the metal layer 25 can be efficiently conducted in the thickness direction of the board main body 21.

In the present embodiment, since the metal layer 25 includes the metal plating layer 26 and the metal member layer 27 composed of a metal member bonded to the metal plating layer 26, the thickness of the metal layer 25 can be ensured, and the heat emitted from the heating element (the insulating circuit board 10 on which the semiconductor element 3 is mounted) can be sufficiently diffused in the planar direction along the metal layer 25, thereby further improving the thermal conductivity. In addition, since the metal plating layer 26 and the metal member layer 27 are bonded to each other by metal, sufficient bonding strength can be secured.

In addition, in the present embodiment, since the bonding layer 28 made of a metal calcined body is formed between the metal plating layer 26 and the metal member layer 27, thermal stress generated when a thermal cycle is applied to the heat transfer plate 20 (the carbonaceous member with a metal layer) can be relaxed in the bonding layer 28, and damage to the heat transfer plate 20 (the carbonaceous member with a metal layer) during a negative heat transfer cycle can be suppressed.

In particular, in the present embodiment, when the porosity of the bonding layer 28 is set to be in the range of 70% to 80%, the thermal stress can be reliably relaxed, and the bonding layer 28 can be suppressed from becoming thermal resistance.

In the present embodiment, since the metal layers 25 are formed on the respective principal surfaces of the plate main body 21, the plate main body 21 can be prevented from warping due to a thermal history when the metal layers 25 are formed.

In the present embodiment, since the irregularities are formed on both main surfaces of the plate body to exhibit the anchoring function between the metal plating layer 26 and the plate body 21, the bonding strength between the metal plating layer 26 and the plate body 21 (carbonaceous member) can be sufficiently improved.

In the present embodiment, since the heat conductive plate 20 is disposed between the insulating circuit board 10 and the heat sink 30, the heat radiated from the insulating circuit board 10 can be diffused in the surface direction in the metal layer 25 formed on one main surface side of the heat conductive plate 20, and the heat can be efficiently transferred in the thickness direction, whereby the heat can be radiated from the heat sink 30. This makes it possible to construct the power module 1 having excellent heat dissipation characteristics.

As described above, the embodiments of the present invention have been described, but the present invention is not limited to these embodiments, and can be modified as appropriate within a range not departing from the technical spirit of the present invention.

For example, in the present embodiment, a description has been given of a mode in which a semiconductor element (power semiconductor element) is mounted on a circuit layer of an insulating circuit board to constitute a power module, but the present invention is not limited to this. For example, an LED module may be configured by mounting an LED element on an insulating circuit board, or a thermoelectric element may be mounted on a circuit layer of the insulating circuit board.

In the present embodiment, the structure in which the metal plating layer and the metal member layer are joined by using the metal paste is described, but the present invention is not limited thereto, and a joining method of the metal plating layer and the metal member layer (metal member) is not particularly limited, and various conventional methods such as a welding method and a diffusion joining method can be used.

For example, as in the heat transfer plate 120 (carbonaceous member with metal layer) shown in fig. 6, when one of the metal plating layer 126 and the metal member layer 127 is made of aluminum or an aluminum alloy and the other of the metal plating layer 126 and the metal member layer 127 is made of copper or a copper alloy, the metal plating layer 126 and the metal member layer 127 may be joined by solid-phase diffusion bonding. In this case, a plurality of intermetallic compounds of copper and aluminum are formed in layers at the interface between the metal plating layer 126 and the metal member layer 127.

As shown in fig. 1, the power module 1 of the present embodiment has a structure in which the heat conductive sheet 20 is disposed between the insulating circuit board 10 and the heat sink 30, but the present invention is not limited thereto, and the method of using the heat conductive sheet (carbonaceous member with metal layer) of the present invention is not particularly limited.

For example, as in the heat conduction plate 220 (carbonaceous member with metal layer) shown in fig. 7, the insulating circuit board 210 may have a structure disposed between the circuit layer 212 and the semiconductor element 3. In this case, the semiconductor element 3 and the circuit layer 212 can be bonded to the heat conductive plate 220 (carbonaceous member with a metal layer) using solder by forming the metal layer 225 of the heat conductive plate 220 (carbonaceous member with a metal layer) with Sn, for example.

As the heat transfer layer of the insulating circuit board 310, a heat transfer plate 320 (carbonaceous member with a metal layer) may be used, as in the heat transfer plate 320 (carbonaceous member with a metal layer) shown in fig. 8. That is, the circuit layer 312 may be formed on one surface of the insulating layer 311, and the heat conduction plate 320 of the present invention may be joined to the other surface of the insulating layer 311 to form the insulating circuit board 310.

Examples

Confirmation experiments performed to confirm the effectiveness of the present invention will be described.

[ experiment 1]

As disclosed in the present embodiment, a molded body is obtained by blending and mixing flat graphite particles and graphene aggregates at a predetermined blending ratio, and molding the mixture by heating under pressure, wherein the graphite particles having a flat structure are laminated with the graphene aggregates as a binder so that their basal surfaces are stacked.

The average particle diameter observed from the basal plane of the graphite particles was 100 μm as measured by a line segment method. The average thickness of the graphite particles was 3 μm as measured by a line segment method. As a result of confirmation in the field range of the electron microscope, the graphene aggregate was 10 layers on average. The average particle size of the graphene aggregate was 5 μm as measured by a line segment method, and the average thickness of the graphene aggregate was 10 μm.

The obtained molded body was cut so that the basal plane of the flat graphite particles extended in the thickness direction of the plate main body and the edge of the flat graphite particles faced the main surface of the plate main body.

In the method described in this embodiment, an Ag plating layer (having a thickness of 2 μm) is directly formed on the surface (edge-laminated surface) facing the edge surface of the plate main body, and a heat conductive plate (carbonaceous member with a metal layer) is obtained. With respect to the obtained heat-conductive sheet, the adhesion of the metal layer was evaluated with reference to JIS K5600-5-6 (adhesion test (cross-cut method)). After the metal layer was formed, the metal layer was crosscut at intervals of 100 μm in a lattice shape, a transparent tape was attached to the crosscut metal layer, and whether or not the metal layer was peeled off when the tape was peeled was confirmed to evaluate the adhesiveness. As a result, it was confirmed that the metal layer was not peeled off and the metal layer and the carbonaceous member were firmly bonded.

As described above, according to the present invention, it is possible to provide a carbonaceous member (heat conductive plate) with a metal layer, which can firmly join a metal layer to a carbonaceous member without intervention of titanium and can efficiently conduct heat.

[ experiment 2]

In order to produce the heat-conducting plates of examples 1 and 2 and comparative examples 1 and 2, carbonaceous members having the arithmetic surface height Sa and the maximum height Sz shown in table 1 were prepared. In order to increase the arithmetic surface height Sa, ozone treatment was performed in example 1.

As the molded article of example 1, the surface of the laminated side of the edge layer was roughened by ozone treatment under the following conditions.

Ozone treatment conditions: the ozone treatment was performed by irradiating ultraviolet rays for 30 minutes.

The edge lamination surfaces of the molded articles of examples 1 and 2 and comparative examples 1 and 2 were observed by a white light interference microscope (0.5 times by 5.5 times with zoom), and the area of 3.02mm × 3.02mm was photographed, and the arithmetic average height Sa and the maximum height Sz of the edge lamination surfaces were measured based on interference fringes. The results are shown in Table 1.

Next, the metal of the metal plating type described in table 1 was directly formed on the edge laminated surface with an average thickness of 2 μm, and the heat conductive sheets (metal layer-containing carbonaceous members) of examples 1 and 2 and comparative examples 1 and 2 were obtained.

A cross-cut test was performed on the heat-conductive sheets of examples 1 and 2 and comparative examples 1 and 2 in the same manner as in experiment 1 to evaluate the adhesion of the metal layer. The results are shown together in Table 1.

[ Table 1]

As shown in Table 1, in examples 1 and 2 in which the arithmetic mean height Sa of the edge laminated surface was 1.1 μm or more and the maximum height Sz was 20 μm or more, the metal plating layer was not peeled off. However, peeling occurred in comparative examples 1 and 2 which did not satisfy the conditions that the arithmetic mean height Sa of the edge laminated surface was 1.1 μm or more and the maximum height Sz was 20 μm or more. In example 1 in which the surface of the edge layer stack was treated with ozone, good bonding strength was also confirmed.

Industrial applicability

According to the present invention, a carbonaceous member with a metal layer and a heat conductive plate using the carbonaceous member with a metal layer can be provided, which can firmly bond a metal layer and the carbonaceous member and can effectively conduct heat, and thus can be industrially used.

Description of the symbols

20. 120, 220, 320-thermally conductive plate (carbonaceous member with metallic layer), 21, 121-plate body (carbonaceous member), 25, 125-metallic layer, 26, 126-metal plating, 27, 127-metallic member layer, 28-bonding layer.