阅读说明：本技术 加热器及其制造方法 (Heater and method of manufacturing the same ) 是由 青山隼辅 我妻和之 于 2021-04-06 设计创作，主要内容包括：本发明提供加热器及其制造方法。所述加热器由表面具有金属箔的基膜和电阻元件构成,所述金属箔形成通过通电发热的加热器电路部,所述加热器电路部与所述电阻元件串联连接。(The invention provides a heater and a method of manufacturing the same. The heater is composed of a base film having a metal foil on a surface thereof, and a resistive element, the metal foil forming a heater circuit portion that generates heat by energization, the heater circuit portion being connected in series with the resistive element.)

1. A heater is characterized in that a heater body is provided with a heating chamber,

comprises a base film with a metal foil on the surface and a resistance element,

the metal foil forms a heater circuit portion that generates heat by energization,

the heater circuit portion is connected in series with the resistance element.

2. A method for manufacturing a heater is characterized in that,

sequentially comprises an etching process, a laminating process and a reflow soldering process,

the etching step includes etching a base film having a metal foil on a surface thereof, and forming a heater circuit portion which is formed of a part of the metal foil and generates heat by energization and an energizing portion which energizes the heater circuit portion by the etching,

in the laminating step, a cover film is provided to cover the surface of the metal foil,

in the reflow step, a resistance element connected in series with the heater circuit portion and a connector electrically connectable to the current-carrying portion are provided by reflow soldering.

Technical Field

The invention relates to a heater and a manufacturing method thereof.

Background

Conventionally, a film heater is used to heat a front windshield of an automobile. In recent years, Advanced Driving Assistance Systems (ADAS) are being developed. Further, the necessity of a film-like heater is increasing for the purpose of antifogging a lens or a front windshield of a camera for detection. In addition, miniaturization of cameras is also advancing. Therefore, miniaturization of the heater is also required. Along with this, it is necessary to advance the reduction in the wire diameter of the wiring for the heater. As a result, it is difficult to keep the heating temperature fluctuation due to the dimensional tolerance of the wiring within the allowable range.

In addition, the conventional film heater has a problem that the number of manufacturing processes is large. A general film heater and a method of manufacturing the same will be described below with reference to fig. 10A, 10B, 11A, 11B, and 11C. Fig. 10A, 10B, 11A, 11B, and 11C are process diagrams illustrating a manufacturing process of a general film heater.

First, the heater wire 510 is formed using a material that generates heat by energization (see fig. 10A). Examples of the material used for the heating wire 510 include alloys such as nickel-chromium alloy, SUS, aluminum, platinum, iron, and nickel, and pure metals. Next, a first insulating film 521 and a second insulating film 522 are respectively provided on both sides of the heating wire 510. The first insulating film 521 and the second insulating film 522 sandwiching the heating wire 510 are bonded to each other by an adhesive layer 523 provided between these films (see fig. 10B). Fig. 10A is a plan view of the heater wire 510. Fig. 10B schematically shows a cross-sectional view of an intermediate article in the process of manufacturing the heater.

Next, an electronic component 530 is mounted on the surface of the first insulating film 521, and is electrically connected to the heater wire 510 (see fig. 11A). In the illustrated example, an insulating film on which only one electronic component 530 is mounted is shown. However, a plurality of electronic components may be mounted. In addition, a thermal fuse can be given as an example of the electronic element 530. Then, the wire harness 540 is electrically connected to the heater wire 510 by various methods such as crimping or welding (see fig. 11B). The connector 550 is electrically connected to an end of the wire harness 540 by a crimp pin (not shown). The connector 550 is connected to a device including a power supply for supplying power to the heater wire 510 or a control device for controlling temperature. The heater 500 is obtained through the above manufacturing process. Fig. 11A and 11B are plan views of an intermediate product in the process of manufacturing the heater. Fig. 11C is a top view of the finished product, i.e., the heater 500. When the heater 500 is obtained through the above manufacturing process, a process of mounting the wire harness 540 and a process of mounting the connector 550 are required, unlike the process of mounting the electronic component 530. Therefore, a plurality of manufacturing processes are involved.

Disclosure of Invention

The invention aims to provide a heater including a flexible printed wiring board and a manufacturing method thereof, wherein the heater can inhibit heating temperature fluctuation and reduce the number of manufacturing processes.

In the present invention, in order to solve the above problems, the following method is adopted.

That is, the heater of the present invention is constituted by a base film having a metal foil on a surface thereof, and a resistance element, the metal foil forming a heater circuit portion that generates heat by energization, the heater circuit portion being connected in series to the resistance element.

According to the present invention, the resistance element is connected in series with the heater circuit portion. Therefore, the voltage applied to the entire heater is divided by the heater circuit portion and the resistance element. As a result, a voltage is applied to each of the heater circuit portion and the resistive element. When the size of the wiring constituting the heater circuit portion is smaller than the reference value within the dimensional tolerance, the voltage value applied to the heater circuit portion also increases by an amount that the resistance value of the heater circuit portion is higher than the reference value. This can suppress a decrease in current value due to the wiring thinner than the reference value. In contrast, when the size of the wiring constituting the heater circuit portion is thicker than the reference value within the dimensional tolerance, the voltage value applied to the heater circuit portion is also reduced by an amount by which the resistance value of the heater circuit portion is lower than the reference value. This can suppress an increase in current value due to the wiring thicker than the reference value.

The method for manufacturing a heater including a flexible printed wiring board according to the present invention includes an etching step of etching a base film having a metal foil on a surface thereof, a heater circuit portion that generates heat by energization and is formed by the etching, and a current-carrying portion that carries current to the heater circuit portion, in which the etching step includes providing a cover film covering the surface of the metal foil, and a reflow step of providing a resistance element connected in series to the heater circuit portion and a connector electrically connected to the current-carrying portion by reflow soldering.

According to the present invention, the heater circuit portion and the current-carrying portion are formed by an etching process. Therefore, the number of manufacturing steps can be reduced. In addition, the resistor element and the connector can be mounted in the reflow step. Therefore, the number of manufacturing steps can be further reduced.

As described above, according to the present embodiment, it is possible to suppress the heating temperature fluctuation and reduce the number of manufacturing steps.

Drawings

Fig. 1A and 1B are circuit diagrams of the heater of the present embodiment and the heater of the reference example.

Fig. 2A and 2B are graphs showing changes over time in voltage values in the heater of the present embodiment and the heater of the reference example.

Fig. 3A and 3B are graphs showing temporal changes in current values in the heater of the present embodiment and the heater of the reference example.

Fig. 4A and 4B are graphs showing changes over time in the temperature of the heater of the present embodiment and the heater of the reference example.

Fig. 5A and 5B are process diagrams for manufacturing the heater including the flexible printed wiring board according to the present embodiment.

Fig. 6A and 6B are process diagrams for manufacturing the heater including the flexible printed wiring board according to the present embodiment.

Fig. 7A and 7B are process diagrams of manufacturing the heater including the flexible printed wiring board according to the present embodiment.

Fig. 8 is a process diagram for manufacturing the heater including the flexible printed wiring board according to the present embodiment.

Fig. 9A, 9B, and 9C are process diagrams of manufacturing the heater including the flexible printed wiring board according to the present embodiment.

Fig. 10A and 10B are process diagrams for manufacturing a general film heater.

Fig. 11A, 11B, and 11C are process diagrams for manufacturing a general film heater.

Detailed Description

In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. It may be evident, however, that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are schematically shown in order to simplify the drawing.

The embodiment is described in detail below by way of example with reference to the accompanying drawings. However, unless otherwise specified, the dimensions, materials, shapes, relative arrangement, and the like of the components described in the embodiment are not limited to the scope of the present embodiment.

(embodiment mode)

A heater including a flexible printed wiring board and a method for manufacturing the heater according to the present embodiment will be described with reference to fig. 1A to 9C. The heater 10 of the present embodiment can be applied to heating a lens or a front windshield of a camera for detection. The heater 10 of the present embodiment is not only used for heating various components constituting an automobile, but also applicable to various devices other than an automobile. The heater 10 of the present embodiment has flexibility. Therefore, the heater 10 can be bent in various directions. Therefore, the heater 10 can be used by being stuck along the curved surface even in the curved portion.

(Heater)

A general configuration of the heater including the flexible printed wiring board according to the present embodiment will be described with reference to fig. 1A and 1B. Fig. 1A is a circuit diagram schematically showing a heater including a flexible printed wiring board according to the present embodiment connected to a power supply. Fig. 1B is a circuit diagram schematically showing a heater including a flexible printed wiring board of a reference example connected to a power supply.

The heater 10 of the present embodiment includes: a heater circuit unit 121 that generates heat by energization; and a resistance element (chip resistor 310 in the present embodiment) connected in series with the heater circuit unit 121. A voltage (constant voltage) is applied to the heater 10 configured as described above by the power supply 400. The heater circuit portion 121 generates heat. The heater 10X of the reference example shown in fig. 1B also includes a heater circuit portion 121 that generates heat by energization. The heater 10X of this reference example differs from the heater of the present embodiment only in that it does not include a resistance element. The heater 10X of the reference example thus configured is also applied with a voltage (constant voltage) by the power supply 400. The heater circuit portion 121 generates heat.

(advantages of the Heater of the present embodiment)

In general, in various products, variations in the dimensions of the respective portions occur due to various influences including raw materials and manufacturing processes. Therefore, a dimensional tolerance is set for the target design value for the dimensions of each part. The heater including the heating wire made of the alloy described in the background art has a comparatively large size. Therefore, the influence of the dimensional tolerance on the heating temperature is small. In contrast, the wiring of the heater including the flexible printed wiring board is formed of a metal foil such as a copper foil. Therefore, the wiring constituting the heater circuit portion 121 can be made thin. On the other hand, if the wire is thinned, the influence of the dimensional tolerance on the heating temperature becomes large. Therefore, the heater 10 of the present embodiment includes the resistance element (chip resistor 310) connected in series to the heater circuit unit 121 as described above. This can suppress fluctuations in heating temperature due to dimensional tolerances of the wiring constituting the heater circuit portion 121. The reason why the heating temperature fluctuation can be suppressed will be described below.

When the voltage of the power source 400 is E [ V ], the resistance value of the heater circuit portion 121 is R1[ Ω ], and the resistance value of the resistance element (chip resistor 310) is R2[ Ω ], the voltage (divided voltage) V1 applied to the heater circuit portion 121 and the voltage (divided voltage) V2 applied to the resistance element have the following relationship.

V1＝(R1÷(R1+R2))×E[V]

V2＝(R2÷(R1+R2))×E[V]

Here, when the size of the wiring constituting the heater circuit section 121 is smaller than the reference value within the dimensional tolerance, the voltage value V1 applied to the heater circuit section 121 also increases the resistance value R1 of the heater circuit section 121 by an amount higher than the reference value. This can suppress a decrease in current value caused by the wiring having a size smaller than a reference value. On the other hand, when the size of the wiring constituting the heater circuit portion 121 is larger than the reference value within the dimensional tolerance, the voltage value V1 applied to the heater circuit portion 121 also decreases by an amount that the resistance value R1 of the heater circuit portion 121 is lower than the reference value. This can suppress an increase in current value due to the wiring size being larger than the reference value. Therefore, fluctuation of the heating temperature due to dimensional tolerance of the wiring constituting the heater circuit portion 121 can be suppressed.

This point will be described in more detail with reference to fig. 2 to 4. Fig. 2A and 2B are graphs showing changes in voltage values of the heater circuit portion with time after voltage is applied to the heater. Fig. 2A shows a heater according to the present embodiment. Fig. 2B shows the case of the reference example. Fig. 3A and 3B are graphs showing changes in the current value of the heater circuit portion with time after the voltage is applied to the heater. Fig. 3A shows a heater according to the present embodiment. Fig. 3B shows the case of the reference example. Fig. 4A and 4B are graphs showing changes in the temperature of the heater circuit portion with time after voltage is applied to the heater. Fig. 4A shows a heater according to the present embodiment. Fig. 4B shows the case of the reference example.

A curve Lvma in fig. 2A represents a case where the wiring in the heater circuit section 121 has a reference value size. The curve Lvta represents the situation where the wiring is thinnest within dimensional tolerances. The curve Lvha represents the case where the wiring is the thickest within dimensional tolerances. A curve Lvmb in fig. 2B represents a case where the wiring in the heater circuit portion 121 has a reference value size. The curve Lvtb represents the finest case of this wiring within the dimensional tolerance. The curve Lvhb represents the coarsest case of the wiring within dimensional tolerances.

As shown in the reference example, when the resistance element is not provided, the voltage of the power supply 400 is directly applied to the heater circuit part 121. Therefore, the same voltage is applied regardless of the wiring size. In contrast, in the case of the heater 10 of the present embodiment, by providing the resistive element, the thinner the wiring in the heater circuit portion 121, the larger the voltage applied to the heater circuit portion 121.

A curve Lima in fig. 3A represents a case where the wiring in the heater circuit section 121 has a reference value size. The curve Lita represents the situation where the wiring is finest within dimensional tolerances. The curve Liha represents the case where the wiring is the thickest within dimensional tolerances. A curve Limb in fig. 3B represents a case where the wiring in the heater circuit portion 121 has a reference value size. The curve Litb represents the finest case of this wiring within the dimensional tolerance. The curve Lihb represents the coarsest case of the wiring within dimensional tolerances.

In the case of the reference example, as described above, the same voltage is applied to the voltage applied to the heater circuit portion 121 regardless of the wiring size. Therefore, the thicker the wiring, the smaller the resistance value. As a result, the amount of current increases. Further, the variation in current value due to the difference in thickness of the wiring increases. Further, since heat is generated by energization, the resistance value increases as the temperature increases. Therefore, the current value gradually decreases until a predetermined time from the start of energization, and then becomes constant. In the reference example, when the wiring is thick, the change in the current value is significant. In contrast, in the case of the heater 10 of the present embodiment, the thicker the wiring, the larger the current value. However, the thinner the wiring, the larger the voltage applied. Therefore, the fluctuation of the current value due to the difference in the thickness of the wiring is reduced. In addition, the variation in current value at the initial stage of energization can be suppressed.

A curve Ltma in fig. 4A represents a case where the wiring in the heater circuit section 121 has a reference value size. The curve Ltta represents the situation where the wiring is thinnest within dimensional tolerances. The curve lth represents the case where the wiring is thickest within dimensional tolerances. A curve Ltmb in fig. 4B represents a case where the wiring in the heater circuit section 121 has a reference value size. The curve Lttb represents the situation where the wiring is thinnest within dimensional tolerances. The curve lth represents the case where the wiring is thickest within dimensional tolerances.

In the case of the reference example, the voltage applied to the heater circuit section 121 is the same regardless of the size of the wiring. The thicker the wiring, the larger the amount of current. Therefore, temperature fluctuation of the heater circuit part 121 due to dimensional tolerance of the wiring increases. In contrast, in the case of the heater 10 of the present embodiment, the thinner the wiring, the larger the voltage applied to the heater circuit portion 121. And, the amount of current becomes small. On the other hand, the thicker the wiring, the smaller the voltage applied to the heater circuit portion 121. And, the amount of current becomes large. Thus, as shown in fig. 4A, temperature fluctuations due to dimensional tolerances of the wiring can be reduced. As described above, according to the heater 10 of the present embodiment, it is possible to suppress fluctuations in heating temperature due to dimensional tolerances of the wiring constituting the heater circuit portion 121. In the case of the heater 10 of the present embodiment, since the applied voltage is controlled to be different depending on the thickness of the wiring, it is possible to suppress a decrease in the heating temperature due to an increase in the resistance value accompanying a temperature increase of the heater circuit portion 121.

(method for manufacturing heater including flexible printed wiring board according to the present embodiment)

A method for manufacturing a heater including a flexible printed wiring board will be described with reference to fig. 5A to 9B in the order of manufacturing steps.

[ PRODUCT ] OF ORGANIC ACID

Fig. 5A and 5B show a raw material 100 used for manufacturing the heater 10 of the present embodiment. Fig. 5A is a plan view showing a part of the material 100. Fig. 5B is a schematic sectional view of the raw material 100 (AA sectional view in fig. 1).

This raw material 100 is commercially available, commonly referred to as a copper clad laminate. The raw material 100 is composed of a base film 110 having a metal foil 120 on a surface thereof. The base film 110 is composed of an insulating resin material having flexibility (e.g., polyimide or polyethylene naphthalate). Further, the metal foil 120 is made of copper foil. The material 100 thus configured has flexibility and can be bent in various directions.

[ etching Process ]

A resist pattern (a portion to be a mask) for forming the heater circuit portion 121 and the conducting portions 122 and 123 on one surface of the material 100 is formed by using a method such as photolithography. Then, etching is performed. Thereby, unnecessary copper foil is removed. Thus, the heater circuit portion 121 and the current-carrying portions 122 and 123 are formed. That is, the heater circuit portion 121 and the current carrying portions 122 and 123 are formed by a part of the metal foil 120. The heater circuit portion 121 and the current-carrying portions 122 and 123 are formed almost simultaneously by etching. Fig. 6A and 6B show the first intermediate product 100X after the etching step is performed. Fig. 6A is a top view of first intermediate article 100X. Fig. 6B is a sectional view of the first intermediate product 100X (BB sectional view in fig. 6A).

In the present embodiment, the width of the heater line in the heater circuit portion 121 is set to be constant. The heater circuit portion 121 is provided with at least 1 row of regions in which the heating lines meander at equal intervals (see fig. 6A). In the present embodiment, 4 rows of meandering regions are provided. However, it is needless to say that the pattern of the heater circuit portion 121 is not limited to the illustrated example. The method for forming the resist pattern is not limited to the photolithography technique. Various known techniques can be employed.

[ laminating Process ]

After the etching step, a cover film 211 is provided to cover the surface of the metal foil 120 (the heater circuit portion 121 and the current-carrying portions 122 and 123). The cover film 211 is bonded to the base film 110 with the heater circuit portion 121 and the current-carrying portions 122 and 123 interposed therebetween by an adhesive layer 212. The cover film 211 is also made of an insulating and flexible resin material, as in the base film 110. The cover film 211 is provided with openings 211a and 211 b.

Fig. 7A and 7B show the second intermediate product 200 after the laminating step. Fig. 7A is a top view of second intermediate article 200. Fig. 7B is a sectional view of the second intermediate product 200 (sectional view CC in fig. 7A). Various known techniques may be employed for the lamination method for providing the cover film 211. Therefore, the description thereof is omitted. Further, the second intermediate product 200 corresponds to a flexible printed wiring board.

[ reflow soldering Process (mounting Process) ]

After the laminating process, the chip resistor 310 and the connector 320 are mounted on the flexible printed wiring board, which is the second intermediate product 200. First, the portions exposed through the openings 211a and 211b and the metal foil 120 (corresponding to the conducting portions 122 and 123) are subjected to surface treatment such as gold plating or water-soluble preflux treatment. Then, soldering is performed in a reflow furnace. Thereby, various components are mounted. That is, in the present embodiment, the chip resistor 310 is connected to the conducting portion 122 by reflow soldering via the opening 211 a. The connector 320 is connected (electrically connectable) to the current-carrying portions 122 and 123 via the opening 211 b. Therefore, the chip resistor 310 and the connector 320 are mounted almost simultaneously in one process. Fig. 8 shows the second intermediate product 200 after the reflow step is performed. Fig. 8 is a top view of the intermediate article. In the present embodiment, the case where the chip resistor 310 and the connector 320 are mounted in the reflow step is described as an example, but other electronic components may be mounted at the same time. For example, a surface-mount type thermal fuse may be mounted on the heater circuit portion 121.

[ cutting procedure ]

After the reflow step, the outer shape is punched out by cutting, and as shown in fig. 9A, 9B, and 9C, a finished heater 10 is obtained. Further, a plurality of heaters 10 can be manufactured from one raw material 100. Fig. 9A is a top view of the finished heater 10. Fig. 9B is a DD cross-sectional view in fig. 9A. Also, fig. 9C is a sectional view of EE in fig. 9A. The general structure of the heater of the present embodiment has been described with reference to fig. 1A. The structure of the heater 10 will be described in more detail below.

The heater 10 in this embodiment includes a heating unit 250 for heating a heating target portion, an electrical wiring unit 260, a chip resistor 310, and a connector 320 provided at an end portion of the electrical wiring unit 260. The connector 320 is provided to connect to a power supply 400 for energizing the heater circuit portion 121. The power supply 400 generally includes a device for performing various controls.

Next, the internal configurations of the heating portion 250 and the electrical wiring portion 260 in the heater 10 will be described. The heater 10 of the present embodiment includes a base film 110, a heater circuit portion 121 and energizing portions 122 and 123 provided on one surface of the base film 110 (see also fig. 6A). The heater circuit portion 121 is energized by a power supply 400 connected to the connector 320 through energizing portions 122 and 123 to generate heat.

The heating portion 250 corresponds to a region where the heater circuit portion 121 is provided. The electric wiring portion 260 corresponds to a region where the current-carrying portions 122 and 123 are provided.

In this way, in the heater 10 of the present embodiment, the heater circuit portion 121 that generates heat by energization is formed by the metal foil 120 provided on the surface of the base film 110. The heater 10 of the present embodiment includes the chip resistor 310 as a resistor element connected in series with the heater circuit unit 121.

(advantages of the method for manufacturing a heater including the flexible printed wiring board of the present embodiment)

According to the heater 10 including the flexible printed wiring board of the present embodiment and the method of manufacturing the same, the heater circuit portion 121 and the current carrying portions 122 and 123 are formed by an etching step. This can reduce the number of manufacturing steps. Therefore, the conventional process of attaching the wire harness is not required. Therefore, the number of parts is reduced. At the same time, the number of manufacturing processes can be reduced. In the reflow step, the chip resistor 310 and the connector 320 can be mounted. Therefore, the number of manufacturing steps can be further reduced.

(others)

The heater described in the above embodiment includes a flexible printed wiring board provided with the metal foil 120 only on one surface of the base film 110. However, in the present embodiment, a flexible printed wiring board including metal foils on both surfaces of a base film can also be used. In this case, the heater circuit portion may be provided on both surfaces thereof. Alternatively, the heater circuit portion may be provided only on one surface of them, and the other surface may have a different function. In addition, in the above embodiments, a chip resistor is mentioned as the resistance element. However, the resistance element in the present embodiment is not limited to the chip resistor. Various resistors such as an axial resistor can be used.

The detailed description has been presented for purposes of illustration and description. Many modifications and variations are possible in light of the above teaching. The detailed description is not intended to be exhaustive or to limit the subject matter described herein. Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the claims is not necessarily limited to the specific features or acts described. Rather, the specific features and acts described are disclosed as example forms of implementing the claims.