JP2017139302A - Circuit configuration, manufacturing method for the same and power supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circuit configuration for efficiently radiating heat from a power device while suppressing the production cost.SOLUTION: In a circuit configuration 10 comprising a heat radiation member 1, an electronic circuit board 3, and a power device 4, the heat radiation member includes a first region R1 in which the electronic circuit board is mounted, and a second region R2 in which the power device is mounted. An adhesive layer 7 is disposed between the first region and the electronic circuit board, and a heat radiation layer 5 is disposed between the second region and the power device. The thermal conductivity at room temperature in the thickness direction of the heat radiation layer is equal to 10 W/mK or more.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a circuit structure, and more particularly to improvement of heat dissipation.

  The power supply device incorporates a power device for controlling the power supplied from the power source and an electronic circuit board on which a control unit for controlling the power device is mounted. When power is supplied to the power device, heat is generated by the internal resistance. With the miniaturization of the power supply device, the density in the power supply device is considered to increase more and more, and countermeasures against the generated heat are an important issue. In this regard, Patent Document 1 teaches that the power device and the heat radiating member are thermally connected via a bus bar to increase the heat radiation efficiency.

JP 2003-164040 A

  In Patent Document 1, the power device is bonded to the heat dissipation member through the bus bar together with the electronic circuit board. Thereby, the heat generated by the power device is transmitted to the bus bar and diffused, and then is transmitted to the heat radiating member.

  When the current supplied to the power device is small, the bus bar can be omitted. In this case, the heat dissipation member and the electronic circuit board are bonded via an adhesive containing a thermosetting resin, and the power device is mounted on the electronic circuit board. Thermosetting resins generally have low thermal conductivity. When particles such as ceramics are added to the thermosetting resin, the thermal conductivity is improved, but the cost is also increased.

  One aspect of the present invention is a circuit structure that includes a heat dissipation member, an electronic circuit board, and a power device, wherein the heat dissipation member includes a first region in which the electronic circuit board is mounted, and the power device. A second region on which is mounted, an adhesive layer is disposed between the first region and the electronic circuit board, and a heat dissipation layer is disposed between the second region and the power device. And the thermal conductivity at normal temperature in the thickness direction of the heat dissipation layer is 10 W / m · K or more.

  Another aspect of the present invention includes a heat radiating member, an electronic circuit board, and a power device, wherein the heat radiating member has a first region in which the electronic circuit board is mounted, and the power device has a heat radiating layer. A second region mounted on the first region, the step of mounting the electronic circuit board on the first region via an adhesive layer, and the second region on the second region, Forming a heat dissipating layer, wherein the step of forming the heat dissipating layer includes forming a ceramic layer by adhering ceramic particles to the second region, and providing a conductor layer on the surface of the ceramic layer. And a step of forming the circuit structure.

  Still another aspect of the present invention relates to a power supply device including the circuit configuration body.

  ADVANTAGE OF THE INVENTION According to this invention, the heat from a power device can be thermally radiated efficiently, suppressing production cost.

It is the top view (a) and sectional view (b) which show the composition of the circuit composition object concerning the embodiment of the present invention. It is sectional drawing ((a)-(e)) explaining the manufacturing method of the circuit structure which concerns on embodiment of this invention. It is sectional drawing which shows the structure of the conventional circuit structure.

[Description of Embodiment of the Invention]
First, the contents of the embodiment of the present invention will be listed and described.
A circuit structure according to the present invention is (1) a circuit structure including a heat dissipation member, an electronic circuit board, and a power device, wherein the heat dissipation member is a first region in which the electronic circuit board is mounted. And a second region on which the power device is mounted, and an adhesive layer is disposed between the first region and the electronic circuit board, and between the second region and the power device. A heat dissipation layer is disposed, and the heat conductivity at normal temperature in the thickness direction of the heat dissipation layer is 10 W / m · K or more. Thereby, the efficiency of heat radiation from the power device is improved. Therefore, it is not necessary to bond the electronic circuit board and the heat radiating member with an expensive adhesive, and the production cost can be suppressed.

  (2) It is preferable that the said heat radiating layer contains the ceramic layer arrange | positioned at the said heat radiating member side, and the conductor layer arrange | positioned at the said power device side. Thereby, the thermal conductivity of the heat dissipation layer is further improved. (3) At this time, it is preferable that a conductive bonding layer is disposed between the conductor layer and the power device.

  (4) The thickness of the ceramic layer is preferably 10 to 200 μm. Moreover, (5) It is preferable that the thickness of the said conductor layer is 10-200 micrometers. This is because the thermal conductivity of the heat dissipation layer is further improved.

  (6) A method of manufacturing a circuit structure according to the present invention includes a heat dissipation member, an electronic circuit board, and a power device, wherein the heat dissipation member includes a first region in which the electronic circuit board is mounted, A second region where a power device is mounted via a heat dissipation layer, and a step of mounting the electronic circuit board on the first region via an adhesive layer; Forming the heat dissipation layer in a second region, the step of forming the heat dissipation layer forming a ceramic layer by adhering ceramic particles to the second region, and the ceramic layer Forming a conductor layer on the surface of the substrate. According to this method, it is possible to obtain a circuit structure that can efficiently dissipate heat from the power device while suppressing costs.

  (7) A power supply device according to the present invention includes the above circuit configuration body. Such a power supply device is excellent in heat dissipation.

[Details of the embodiment of the invention]
An embodiment of the present invention will be specifically described below. In addition, this invention is not limited to the following content, but is shown by the claim, and it is intended that all the changes within the meaning and range equivalent to a claim are included.

  The circuit structure according to the present embodiment includes a heat dissipation member, an electronic circuit board, and a power device. Such a circuit structure is suitable when the current supplied to the power device is small (for example, 30 A or less). Moreover, the power supply device which concerns on this embodiment is provided with the said circuit structure.

  A power device is a semiconductor that controls and supplies power, and is controlled by a control unit mounted on an electronic circuit board. Electric power is supplied from a predetermined power source to the power device. The heat dissipating member is disposed to release heat generated by the power device to the outside of the power supply device. Therefore, the heat dissipation member and the power device are thermally connected.

[Heat dissipation member]
The heat dissipation member plays a role of radiating heat generated by the power device to the outside of the power supply device. The material of the heat radiating member is not particularly limited as long as it has a high thermal conductivity (for example, 20 W / m · K or more, hereinafter the same), for example, aluminum (Al), copper (Cu), stainless steel, etc. These metals and ceramics described later can be used. Of these, Al is preferable because it is easy to mold.

  The shape of the heat dissipating member is not particularly limited, and may be a flat plate shape or a box shape (casing body) that can accommodate a circuit component. When the heat dissipating member has a flat plate shape, the circuit structural body may be housed in a box-shaped heat sink and thermally connected to the heat sink, or may be thermally connected to the housing in which the power supply device is housed. May be. Although the thickness (thickness) of a heat radiating member is not specifically limited, It is preferable that it is 3-10 mm from a heat dissipation viewpoint.

  As shown in FIG. 3, the power device 104 is conventionally bonded to the heat dissipation member 101 together with the electronic circuit board 103. Thereby, the heat generated in the power device 104 is transmitted to the heat radiating member 101. Adhesion between the heat dissipation member 101 and the power device 104 is performed via an adhesive layer 107. In order to increase the efficiency of heat dissipation, for the adhesive layer 107, for example, a resin composition in which particles having high thermal conductivity such as ceramics are mixed with a thermosetting resin such as an epoxy resin or a silicone resin is used. In this case, the production cost increases. Alternatively, a plurality of power devices are used to reduce the current flowing through one power device. Thereby, the generated heat is dispersed on the heat radiating member, and the effect of heat dissipation is enhanced. In this case, since it is necessary to mount a plurality of power devices on the heat dissipating member and connect them in parallel, it is difficult to reduce the size of the circuit structure 100 and the cost also increases. In addition, the type and shape of the power device used are limited.

  In this embodiment, among the electronic components mounted on the heat dissipation member, an electronic component that generates a large amount of heat is thermally connected to the heat dissipation member via the heat dissipation layer. That is, in the circuit structure, the power device is thermally connected to the heat dissipation member via the heat dissipation layer. On the other hand, the electronic circuit board is bonded to the heat dissipation member via the bus bar and the adhesive layer. In this way, the heat dissipation member is divided into a first region where the electronic circuit board is mounted and a second region where the power device is mounted, and the second region is powered through a heat dissipation layer with high thermal conductivity. Mount the device. In the first region, since it is less necessary to consider heat dissipation, an adhesive that does not contain ceramics or the like can be used. That is, it is not necessary to apply a high-cost adhesive with high thermal conductivity on the entire surface of one surface of the heat dissipation member as in the past. Therefore, the production cost is suppressed. Further, since it is not always necessary to use a plurality of power devices, it is advantageous for downsizing the circuit structure. Furthermore, it is not necessary to arrange common components (for example, an electronic circuit board) in the first region and the second region, and the configuration of the heat dissipation member can be changed, so that the degree of freedom in design is increased. improves. For example, as will be described later, a heat radiating member having a convex portion can be used.

[Power device]
A power device is a semiconductor that controls power supplied from a power source and supplies the controlled power to other electronic components and loads. Examples of the power device include a diode, a transistor, and an integrated circuit (IC, LSI, etc.) in which these are integrated. Among these, transistors are preferably used because they have a wide application range. Typical transistors include bipolar transistors such as IGBT (Insulated Gate Bipolar Transistor), MOSFETs (metal-oxide-semiconductor field-effect transistors), and the like. These are properly used according to the magnitude of power to be handled. A plurality of power devices may be arranged in the second region.

[Heat dissipation layer]
When power is supplied to the power device, the power device generates heat due to the internal resistance. Therefore, the power device is thermally connected to the heat radiating member, and the heat generated by the power device is released to the outside of the power supply apparatus. On the other hand, the power device and the heat dissipation member need to be electrically insulated. Therefore, the power device and the heat dissipation member are connected via an insulating layer. When the heat dissipation layer is a laminate of a plurality of layers, it is only necessary to insulate the power device and the heat dissipation member as the entire heat dissipation layer. The heat dissipation layer includes an insulating layer and a conductive layer (for example, a conductor layer described later). May be included.

  The heat dissipating layer is disposed to transmit heat generated from the power device to the heat dissipating member. The heat conductivity in the thickness direction of the heat dissipation layer is 10 W / m · K or more at room temperature (for example, 15 to 25 ° C.). Especially, it is preferable that the heat conductivity of a thermal radiation layer is 20 W / m * K. The thermal conductivity is a numerical value measured according to JIS A 1412-2.

  The material of the insulating layer is not particularly limited as long as it is a material having high thermal conductivity and high insulating properties. Examples of such a material include ceramics and thermosetting resins (thermally conductive thermosetting resins) containing ceramic particles. Among these, from the viewpoint of heat dissipation, the heat dissipation layer preferably includes a ceramic having high thermal conductivity, and more preferably includes a continuous body of ceramic particles (hereinafter referred to as a ceramic layer). From the viewpoint of heat dissipation, the ceramic layer is preferably in contact with the second region.

  Such a ceramic layer can be formed by a method in which ceramic particles are adhered to the surface of the heat dissipation member. This method will be described later. Ceramic particles forming the ceramic layer may be bonded (diffusion bonded) by atomic diffusion or may be just in contact. In the ceramic layer, ceramic particles are diffused or brought into contact with each other to form a continuous body of ceramic particles.

Examples of ceramics having a thermal conductivity of 20 W / m · K or more include silicon carbide (SiC), aluminum nitride (AlN), silicon nitride (SiN), aluminum oxide (Al ₂ O ₃ ), and the like. Of these, aluminum oxide is preferred because it is particularly excellent in thermal conductivity and electrical insulation and has high corrosion resistance.

When the heat dissipation layer includes a ceramic layer, it is preferable to dispose a conductor layer on the surface of the ceramic layer facing the power device. From the viewpoint of heat dissipation, the conductor layer is preferably in contact with the ceramic layer. In this case, the heat dissipation layer is a composite layer of a ceramic layer and a conductor layer. The conductor layer functions as a connection terminal for the power device. Thereby, a power device and an electronic circuit board can be electrically connected via a conductor layer. When the heat dissipation layer is a composite layer as described above, the thermal conductivity of the heat dissipation layer can be calculated from the thermal conductivity and thickness of the constituent material of each layer using the following approximate calculation formula.
(L ₁ + L ₂ ) / (μS) = L ₁ / (μ ₁ S) + L ₂ / (μ ₂ S)
In the formula, μ is the thermal conductivity of the heat dissipation layer, μ ₁ is the thermal conductivity of the ceramic layer, μ ₂ is the thermal conductivity of the conductor layer, and S is the heat dissipation layer in which the ceramic layer and the conductor layer are laminated. , L ₁ is the thickness of the ceramic layer, and L ₂ is the thickness of the conductor layer.

  The heat dissipation layer and the power device may be bonded via a bonding layer. In this case, it is preferable that the bonding layer also has a high thermal conductivity. Moreover, when a heat-radiating layer contains a ceramic layer and a conductor layer, it is preferable that a joining layer has electroconductivity further. Such a bonding layer is formed, for example, by melting or curing a bonding material including a thermosetting resin containing solder and conductive filler (for example, solder particles, silver particles, etc.). Especially, it is preferable that a joining layer is formed with a solder from a heat dissipation and electroconductive viewpoint. The thickness of the bonding layer is not particularly limited. Especially, it is preferable that the thickness of a joining layer is 50-100 micrometers from a heat dissipation viewpoint.

  The conductor layer only needs to contain a metal material, and may be a metal layer formed by depositing a metal material or a layer containing a sintered body of metal material particles (metal particles). Such a conductor layer has a high thermal conductivity. The metal material is not particularly limited. For example, when the bonding layer includes solder, the conductor layer preferably includes nickel (Ni), tin (Sn), Cu, gold (Au), or the like as a metal material in terms of improving the wettability of the solder. These may be used alone or in combination of two or more. Two or more metal materials may be included in the conductor layer as a laminate of two or more metal layers. From the viewpoint of heat dissipation, the thickness of the ceramic layer and the conductor layer is preferably 10 to 200 μm, and more preferably 25 to 100 μm. The thickness of the heat dissipation layer is preferably 20 to 400 μm and more preferably 50 to 200 μm from the viewpoint of heat dissipation.

[Electronic circuit board]
The electronic circuit board is an electronic component on which a control unit for controlling the operation of the power device is mounted, and is electrically connected to the power device. The electronic circuit board is not particularly limited, and may be a rigid board or a flexible board. A control unit is mounted on the electronic circuit board. Furthermore, electronic components other than the control unit can be mounted on the electronic circuit board via a bonding material such as solder.

  Hereinafter, the circuit structure of the present embodiment will be described with reference to FIG. FIG. 1A is a top view illustrating a configuration example of a circuit structure, and FIG. 1B is a cross-sectional view taken along line BB in FIG.

  The circuit structure 10 includes a heat dissipation member 1, an electronic circuit board 3, and a power device 4. The heat radiating member 1 is divided into a first region R1 and a second region R2, and an electronic circuit board 3 is mounted on the first region R1, and a power device 4 is mounted on the second region.

  In the first region R1, the heat dissipation member 1 and the electronic circuit board 3 are bonded and insulated by the adhesive layer 7. In the second region R2, the heat radiating member 1 and the power device 4 are joined and insulated via the heat radiating layer 5 including the ceramic layer 5a and the conductor layer 5b and the bonding layer 6. The electronic circuit board 3 and the power device 4 are connected by wiring 8.

  As described above, the heat radiating member 1 is divided into two regions (first region R1 and second region R2), and at least components (excluding the power device 4) arranged in the second region R2 and the second region R2. By increasing the thermal conductivity, it is possible to improve the efficiency of heat dissipation while suppressing the production cost.

  Such a circuit structure 10 includes, for example, a step of mounting the electronic circuit board 3 in the first region R1 via the adhesive layer 7 and a step of forming the heat dissipation layer 5 in the second region R2. Manufactured by. At this time, the step of forming the heat dissipation layer 5 includes a step of forming ceramic layers 5a by attaching ceramic particles to the second region R2, and a step of forming the conductor layer 5b on the surface of the ceramic layer 5a. It is preferable to provide. Either the step of mounting the electronic circuit board 3 or the step of forming the heat dissipation layer 5 may be performed first. Hereinafter, with reference to FIG. 2, each step will be described in detail by taking as an example the case where the heat dissipation layer 5 is formed first.

(Heat dissipation layer forming process)
In the heat dissipation layer forming step, the heat dissipation layer 5 including the ceramic layer 5a and the conductor layer 5b is formed in a partial region (second region R2) of the heat dissipation member 1.

  First, ceramic layers 5a are formed by attaching ceramic particles to predetermined positions in the second region R2 of the heat dissipation member 1 (FIG. 2A). Since the ceramic particles are directly adhered to the heat radiating member 1, the ceramic layer 5a can be formed on the heat radiating member 1 without impairing the high thermal conductivity of the ceramic. Furthermore, the formed ceramic layer 5a can be thinned. Therefore, the thermal resistance of the heat dissipation layer 5 can be reduced.

  Examples of methods for attaching ceramic particles to the second region R2 include vapor deposition, physical vapor deposition (PVD), chemical vapor deposition (CVD), thermal spraying, cold spraying, and aerosol deposition (AD). It is done. At this time, the ceramic layer 5a can be formed at a predetermined position in the second region R2 by applying a mask to the heat radiating member 1 and attaching ceramic particles as necessary.

  Among the above, the AD method is preferably used as a method for attaching ceramic particles. The AD method is a method in which ceramic or metal particles are sprayed onto a target together with a gas at high speed to form a film, and a dense layer can be obtained at room temperature. The average particle diameter of the raw ceramic particles is not particularly limited. Especially, it is preferable that the average particle diameter of the raw material ceramic particles is 200 nm or less in that a denser ceramic layer 5a can be formed. The average particle diameter is a median diameter D50 in a volume particle size distribution obtained by a laser diffraction type particle size distribution measuring apparatus. Note that the average particle diameter of the ceramic particles attached to the second region R2 by the AD method can be smaller than that of the raw material.

  Subsequently, the conductor layer 5b is formed on the surface of the ceramic layer 5a (FIG. 2B). The method for forming the conductor layer 5b is not particularly limited. For example, a method in which a conductive paste in which metal particles are dispersed in a binder resin is applied, followed by baking, chemical plating, vapor deposition, PVD, CVD, thermal spraying, cold Examples thereof include a spray method and an AD method. Among these, the AD method is preferably used as a method for forming the conductor layer 5b. In this case, the average particle diameter of the raw metal particles is not particularly limited, but is, for example, about 0.2 μm. Examples of the binder resin include cellulose such as ethyl cellulose, acrylic resin, butyral resin, phenol resin, and epoxy resin. The binder resin preferably has a decomposition temperature of 500 ° C. or lower.

(Electronic circuit board mounting process)
In the electronic circuit board mounting step, the electronic circuit board 3 is mounted through the adhesive layer 7 in the first region R1 (FIG. 2C). At this time, as the electronic circuit board 3, an electronic circuit board with a bus bar having a built-in bus bar may be used.

  The adhesive layer 7 may be formed by applying a paste containing a thermosetting resin to a predetermined position of the first region R1 by screen printing or a dispenser, or a sheet containing a thermosetting resin may be formed in the first region. You may form by sticking to the predetermined | prescribed position of R1. After mounting the electronic circuit board 3 in the first region R1 via the adhesive layer 7, the adhesive layer 7 may be cured by heat treatment before the reflow process.

  After the heat radiation layer 5 is formed, the bonding layer 6 is formed on the surface (FIG. 2D), and the power device 4 is mounted (FIG. 2E). The bonding layer 6 is, for example, a solder paste containing solder particles dispersed in a resin component such as rosin. The solder paste is applied to the surface of the heat dissipation layer 5 by screen printing or the like. At this time, the bonding layer 6 may be formed on the surface of the electronic circuit board 3, and another electronic component 40 may be mounted on the electronic circuit board 3. Then, the circuit structure 10 is completed by performing a reflow process.

  The heat radiating member 1 may include a convex portion (not shown) at a position facing the heat radiating layer 5 in the second region R2. Thereby, the level | step difference between the upper surface of the electronic circuit board 3 and the upper surface of the thermal radiation layer 5 can be made small. Therefore, when another electronic component is mounted on the electronic circuit board 3 via a bonding material such as solder, the step of forming the bonding layer 6 on the upper surface of the heat dissipation layer 5 and the bonding layer on the upper surface of the electronic circuit board 3 6 can be performed in one step.

  The convex portion is formed, for example, by pressing (embossing) the raw material plate of the heat dissipation member 1. When the heat radiating member 1 is a box shape, the heat radiating member 1 can be produced by a die casting method using a mold having a shape corresponding to a convex portion and a predetermined box shape. The height of the protrusion (the step between the surface on which the electronic circuit board 3 in the first region R1 is mounted and the surface on which the power device 4 in the second region R2 is mounted) depends on the thickness of the electronic circuit substrate 3 What is necessary is just to set suitably according to. Especially, the height of the convex portion is such that the difference between the height of the upper surface of the electronic circuit board 3 and the height of the upper surface of the heat dissipation layer 5 is 0.1 to 2 mm when the circuit component 10 is placed on a horizontal plane. It is preferable to set to.

(Power supply)
The power supply device according to this embodiment includes the circuit configuration body 10. Therefore, this power supply device is excellent in heat dissipation.

  Since the circuit structure of the present invention can efficiently dissipate heat from the power device while suppressing the production cost, it can be applied to various power supply apparatuses.

  1: heat dissipation member, 3: electronic circuit board, 4: power device, 5: heat dissipation layer, 5a: ceramics layer, 5b: conductor layer, 6: bonding layer, 7: adhesive layer, 8: wiring, 10, 100: circuit Structure: 40: electronic component, 101: heat dissipation member, 103: electronic circuit board, 104: power device, 107: adhesive layer

Claims (7)

A circuit structure comprising a heat dissipation member, an electronic circuit board, and a power device,
The heat dissipation member includes a first region where the electronic circuit board is mounted, and a second region where the power device is mounted,
An adhesive layer is disposed between the first region and the electronic circuit board;
A heat dissipation layer is disposed between the second region and the power device;
The circuit structure whose thermal conductivity in normal temperature of the thickness direction of the said heat radiating layer is 10 W / m * K or more.   The circuit structure according to claim 1, wherein the heat dissipation layer includes a ceramic layer disposed on the heat dissipation member side and a conductor layer disposed on the power device side.   The circuit structure according to claim 2, wherein a bonding layer is disposed between the conductor layer and the power device.   The circuit structure according to claim 2 or 3, wherein the ceramic layer has a thickness of 10 to 200 µm.   The circuit composition object according to any one of claims 2 to 4 whose thickness of said conductor layer is 10-200 micrometers. A heat dissipation member, an electronic circuit board, and a power device;
The heat dissipation member is a method for manufacturing a circuit structure including a first region where the electronic circuit board is mounted and a second region where the power device is mounted via a heat dissipation layer,
Mounting the electronic circuit board on the first region via an adhesive layer;
Forming the heat dissipation layer in the second region,
The step of forming the heat dissipation layer includes a step of forming ceramic layers by attaching ceramic particles to the second region, and a step of forming a conductor layer on the surface of the ceramic layer. Manufacturing method. A power supply apparatus provided with the circuit structure as described in any one of Claims 1-5.

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