JP2017098477A - Manufacturing method of circuit structure body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a circuit structure body, capable of simplifying a formation of a plurality of conducting path connected to a circuit board and a handling.SOLUTION: A manufacturing method of a circuit structure body, comprises: a fastening step of adhering a first prepreg 31 to a back surface 40R of a metal plate member 40 having a front surface 40S and a back surface 40R, heating and pressing the first prepreg 31, and thereby fastening the first prepreg 31 to the back surface 40R of the metal plate member; and a first etching step of forming a slit SL by etching the metal plate member 40 in a state where the first prepreg 31 is fastened to the back surface 40R of the metal plate member, and forming a plurality of conducting paths 40A arranged so as to be separated by the slit SL each other.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a method of manufacturing a circuit structure, and more particularly to a method of forming a plurality of conductive paths connected to a circuit board included in the circuit structure.

The thing of patent document 1 is known as a some conductive path connected to the circuit board contained in a circuit structure. In this device, a plurality of bus bars made of copper or a copper alloy are used as the plurality of conductive paths.
JP2015-82890A

  However, the plurality of bus bars (conducting paths) described in Patent Document 1 are usually formed by punching a copper plate with a press. Moreover, when joining with the electronic component on a circuit board, if a several bus bar is performed in the state isolate | separated separately, since joining operation will become complicated, each bus bar will be joined with an electronic component in the connected state. Therefore, a dividing operation for dividing each bus bar after joining is required. Further, even after the division, the handling of the combined substrate of the circuit board and the bus bar requires carefulness so that the bus bar does not come off from the circuit board.

  The technology disclosed in this specification has been completed based on the above-described circumstances, and a circuit structure manufacturing method that can simplify the formation and handling of a plurality of conductive paths connected to a circuit board. provide.

  In the method of manufacturing a circuit structure disclosed in the present specification, a first prepreg is bonded to the back surface of a metal plate material having a front surface and a back surface, the first prepreg is heated and pressurized, and the first prepreg is attached to the metal plate material. An adhering step for adhering to the back surface of the metal plate, a first etching step for forming a plurality of conductive paths spaced apart from each other by the slit, and a heat generating electronic component. A first opening forming step of forming a first opening for connecting the heat generating electronic component to a corresponding conductive path on a circuit board on which the electronic component is mounted; and a second prepreg corresponding to the first opening. A second opening forming step of forming a second opening having an opening area equal to or larger than the area of the first opening at a position; and the second prepreg and the circuit board on the plurality of conductive paths. An integration step of laminating the second prepreg and the circuit board in this order, heating and pressurizing the second prepreg, and integrating the plurality of conductive paths, the second prepreg, and the circuit board; including.

  According to this configuration, the plurality of conductive paths arranged apart from each other is formed by etching the metal plate material to which the first prepreg is fixed. Therefore, there is no need for a pressing step and a die for punching the conductive path. In addition, since each conductive path is fixed by the first prepreg, a plurality of connected conductive paths are connected to the circuit board as compared with a conductive path (bus bar) formed using a conventional pressing process and a mold. There is no need to divide the plurality of conductive paths after joining. Therefore, the number of steps for forming a plurality of conductive paths can be reduced, and deformation at the time of handling after joining the plurality of conductive paths to the circuit board can be prevented. That is, the formation and handling of a plurality of conductive paths connected to the circuit board can be simplified.

In the method of manufacturing a circuit structure, a conductive path having a convex portion that is fitted into the first opening and the second opening and connected to the heat generating electronic component by etching the plurality of conductive paths. Including a second etching step to be formed, and in the integration step, the second prepreg is heated and pressurized in a state where the convex portion is fitted into the first opening and the second opening, and the plurality The conductive path, the second prepreg, and the circuit board may be integrated.
According to this configuration, the plurality of conductive paths are etched to form a conductive path having a convex portion. Therefore, the thickness of the conductive path can be adjusted by adjusting the etching amount. Accordingly, an appropriate thickness of the conductive path corresponding to the amount of current flowing through the conductive path can be selected by a simple method.

  Moreover, when the convex part of the conductive path is fitted into the first opening and the second opening, when the second prepreg is heated and pressurized, the second prepreg passes through the first opening and the second opening. Leaking to the surface of the circuit board. Further, by adjusting the height of the protrusion (etching amount of the conductive path), the step difference from the heat generating electronic component connected to the protrusion can be adjusted.

Further, in the method of manufacturing a circuit component, the mounting step of attaching a heat radiating plate to the surface of the first prepreg opposite to the surface bonded to the metal plate material, and mounting the electronic component of the circuit board A resist forming step of forming a solder resist film on the surface to be formed, wherein the first prepreg, the second prepreg, and the solder resist film have a thermal conductivity of 1 W / (mK) or more. May be.
According to this configuration, a synthetic resin having a thermal conductivity of 1 W / (mK) or more is used for the synthetic resin portion, that is, for the first and second prepregs and the solder resist film. The second prepreg is also filled in the slits between the conductive paths by the integration process. Therefore, the heat from each conductive path is transferred to the entire second prepreg in a planar manner and is equalized. Thereby, heat from each conductive path is radiated not only from the heat radiating plate but also from the circuit board side. As a result, the heat dissipation of heat from each conductive path can be improved.

  According to the method for manufacturing a circuit structure disclosed in this specification, the formation and handling of a plurality of conductive paths connected to a circuit board can be simplified.

The fragmentary sectional view which shows the circuit structure which concerns on one Embodiment roughly Sectional drawing which shows the state by which the 1st prepreg was fixed to the metal plate material Sectional drawing which shows the state which formed the slit by the etching of a metal plate material Sectional drawing which shows the state which formed the convex part by the etching of the conductive path Schematic cross section of circuit board Sectional drawing which shows the state by which the opening part was formed in the circuit board Sectional drawing which shows the relationship between a convex part and an opening part Sectional drawing which shows the state by which the convex part was engage | inserted by the opening part, and the 2nd prepreg was heated and pressurized.

<Embodiment>
An embodiment according to a method for manufacturing a circuit structure will be described with reference to FIGS. The circuit structure 1 constitutes a DC-DC converter mounted on a vehicle, for example.

1. Configuration of Circuit Structure As shown in FIG. 1, the circuit structure 1 includes a solder resist film 10, a circuit board 20, a second prepreg 32, a first conductive path 41, a second conductive path 42, and a first prepreg from the top. 31, an aluminum heat sink 50, and a slit SL.

  On the surface of the circuit board 20 (upper surface in FIG. 1), a power semiconductor element (an example of a “heat generating electronic component”) 21 such as a MOSFET and electronic components such as a capacitor, a coil, and a resistor (not shown) are mounted. The heat generating electronic component is not limited to a power semiconductor element.

  In addition, substrate conductive paths 22 connected to electronic components are formed on the front and back surfaces (lower surface in FIG. 1) of the circuit board 20 (see FIG. 5). The circuit board 20 has a first opening 23 for connecting the power semiconductor element 21 to the second conductive path 42.

  The slit SL separates the metal plate 40 with the first prepreg 31 fixed to the back surface 40R of the metal plate 40 having the front surface 40S and the back surface 40R into a plurality of conductive paths 41 and 42 in a state where the first prepreg 31 is fixed. (See FIG. 4).

  The second prepreg 32 is provided between the plurality of conductive paths 41 and 42 and the circuit board 20, and is integrated with the plurality of conductive paths 41 and 42 and the circuit board 20 by being heated and pressurized. . Further, in the second prepreg 32, a second opening 33 having an opening area larger than the area of the first opening 23 is formed at a position corresponding to the first opening 23 of the circuit board 20 (FIG. 7). reference).

  Each of the conductive paths 41 and 42 has etched etching side walls 41W and 42W, and the slit SL is constituted by the etching side walls 41W and 42W. In other words, the slit SL is formed by etching the metal plate 40 when forming the conductive paths 41 and 42 (see FIG. 3).

  The plurality of conductive paths 41, 42 include a first conductive path 41 having an etched etching surface 41 </ b> S and a second conductive path 42 having a protrusion 43 projecting from the etching surface 42 </ b> S toward the circuit board. The protrusion 43 is fitted into the first opening 23 and the second opening 33. That is, the plurality of conductive paths 41 and 42 and the circuit board 20 are integrated by the second prepreg 32 in a state where the convex portion 43 is fitted in the first opening 23 and the second opening 33.

  The heat radiating plate 50 is, for example, an aluminum heat radiating plate, and is provided in contact with the back surface 31R of the first prepreg 31, in other words, the surface 31R opposite to the surface (front surface) 31S to which the metal plate material 40 is bonded. .

  A solder resist film 10 is formed on the surface 20S on which electronic components of the circuit board 20 are mounted. The first prepreg 31, the second prepreg 32, and the solder resist film 10 have a thermal conductivity of 1 W / (mK) or more.

  A through hole 60 that penetrates the circuit board 20 and the second prepreg 32 and reaches the first conductive path 41 is formed. The wall of the through hole 60 is, for example, copper-plated 61, and the first conductive path 41 and the board conductive path 22 formed on the surface of the circuit board 20 are electrically connected by the copper plating 61. .

2. Next, a method for manufacturing the circuit structure 1 will be described.
First, as shown in FIG. 2, the 1st prepreg 31 is adhere | attached on the back surface 40R of the metal plate material 40 which has the surface 40S and the back surface 40R. Then, the first prepreg 31 is heated and / or pressurized to be cured, and the first prepreg 31 is fixed to the back surface 40R of the metal plate 40 (fixing step). Here, the metal plate 40 is made of, for example, a copper plate or a copper alloy plate. The thickness of the metal plate 40 is preferably 140 μm (micrometer) or more. The metal plate 40 is not limited to a copper plate or a copper alloy plate.

  Next, as shown in FIG. 3, in a state where the first prepreg 31 is fixed to the back surface 40R of the metal plate member 40, the metal plate member 40 is etched to form the slit SL (first etching step). The metal plate 40 is separated by the slit SL into a plurality of conductive paths 40A that are spaced apart from each other. At this time, each conductive path 40A is fixed to the first prepreg 31 and therefore does not fall apart.

  Next, by etching the surface 40S of the plurality of conductive paths 40A, as shown in FIG. 4, the first conductive paths 41 and the second conductive paths 42 having the convex portions 43 are formed (second etching step). That is, portions of the plurality of conductive paths 40 </ b> A excluding the convex portion 43 where the power semiconductor element 21 is mounted are made lower than the convex portion 43 by etching. In order to adjust the height of the convex portion 43, the convex portion 43 may also be etched.

  Further, the circuit board 20 (see FIG. 5) including the board conductive path 22 for connecting the electronic components is formed by a known method. Next, as shown in FIG. 6, the first opening 23 for connecting the power semiconductor element 21 to the corresponding second conductive path 42 is formed in the circuit board 20 (first opening forming step).

  Further, as shown in FIG. 7, the second opening 33 having an opening area equal to or larger than the area of the first opening 23 is formed at the position of the second prepreg 32 corresponding to the first opening 23 of the circuit board 20. (Second opening forming step). In the present embodiment, as shown in FIG. 7, the opening area of the first opening 23 and the opening area of the second opening 33 are equal.

  Next, the second prepreg 32 and the circuit board 20 are laminated on the plurality of conductive paths 41 and 42 in the order of the second prepreg 32 and the circuit board 20 (see FIG. 7). Then, as shown in FIG. 8, the second prepreg 32 is heated and pressurized to integrate the plurality of conductive paths 41, 42, the second prepreg 32, and the circuit board 20 (integration step). At that time, the slit SL is filled with the second prepreg 32. In the present embodiment, the second prepreg 32 is heated and / or pressurized in a state in which the convex portion 43 of the second conductive path 42 is fitted in the first opening 23 and the second opening 33, so that a plurality of The conductive paths 41 and 42, the second prepreg 32, and the circuit board 20 are integrated.

  Next, as shown in FIG. 8, the circuit board 20 and the second prepreg 32 are penetrated by a laser or a drill to form a through hole 60 reaching the first conductive path 41. The through hole 60 is made of, for example, Cu (copper). Plate by. Thereby, the substrate conductive path 22 of the circuit board 20 and the first conductive path 41 are electrically connected. Next, the solder resist film 10 is formed at a predetermined position on the surface of the circuit board 20 by, for example, printing (resist forming step).

  Next, as shown in FIG. 1, the power semiconductor element 21 is connected to the convex portions 43 of the substrate conductive path 22 and the second conductive path 42 on the circuit board 20, and other electronic components are connected to the substrate conductive path on the circuit board 20. Connect to path 22. Each connection is made by, for example, reflow soldering. Further, a heat radiating plate 50, for example, aluminum heat radiation is attached to the back surface 31R of the first prepreg 31, in other words, the surface 31R of the first prepreg opposite to the surface 31S bonded to the metal plate 40 (attachment process). ). The heat sink 50 is attached by, for example, providing a screw hole (not shown) reaching the heat sink 50 from the circuit board 20 and screwing. Thus, the circuit structure 1 as shown in FIG. 1 is formed.

3. Effects of the Embodiment A plurality of conductive paths 40A (41, 42) arranged apart from each other are formed by etching the metal plate 40 to which the first prepreg 31 is fixed. Therefore, there is no need for a pressing step and a die for punching the conductive path 40A. Each conductive path 40 </ b> A is fixed by a first prepreg 31. Therefore, compared with the conductive path (bus bar) formed by using a conventional pressing process and a mold, the connected first and second conductive paths (a plurality of conductive paths) (41, 42) are arranged on the circuit board 20. It is not necessary to divide the first and second conductive paths (41, 42) after being joined to each other. Therefore, the number of steps for forming the first and second conductive paths (41, 42) can be reduced, and deformation during handling after the first and second conductive paths (41, 42) are joined to the circuit board 20, etc. Can be prevented. That is, the formation and handling of the plurality of conductive paths 40A (41, 42) connected to the circuit board 20 can be simplified.

  The plurality of conductive paths 40 </ b> A are etched to form a first conductive path 41 and a second conductive path 42 having a convex portion 43. Therefore, the thickness (height) of the first conductive path 41 and the second conductive path 42 can be adjusted by adjusting the etching amount. Accordingly, it is possible to select an appropriate thickness of the conductive paths 41 and 42 corresponding to the amount of current flowing through the first conductive path 41 and the second conductive path 42 by a simple method.

  Further, the convex portion 43 of the second conductive path 42 is fitted into the first opening portion 23 and the second opening portion 33. Thereby, when the second prepreg 32 is heated and pressurized, the second prepreg can be prevented from leaking to the surface 20 </ b> S of the circuit board 20 through the first opening 23 and the second opening 33. Further, by adjusting the height of the convex portion 43 (the amount of etching of the conductive path), the step difference from the power semiconductor element 21 (heat generating electronic component) connected to the convex portion 43 can be adjusted.

  The first prepreg 31, the second prepreg 32, and the solder resist film 10 have a thermal conductivity (high thermal conductivity) of 1 W / (mK) or more. Therefore, heat radiation from the first and second conductive paths (41, 42) can be performed not only from the heat radiating plate 50 but also from the circuit board 20 side.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention.

(1) In the present embodiment, the example in which the second conductive path 42 having the convex portion 43 is formed in the second etching step is shown, but the present invention is not limited to this. That is, in the second etching step, the second conductive path 42 having the convex portions 43 may not be formed, and the first conductive path 41 may be formed entirely. At this time, the opening area of the second opening 33 is formed so as to be larger than the opening area of the second opening 33 so that the first opening 23 is located in the second opening 33 in plan view. Is preferred. With such a configuration, it is possible to prevent the second prepreg 32 from leaking to the surface 20S of the circuit board 20 when the second prepreg 32 is heated and pressurized.
Furthermore, the second etching step may be omitted. In this case, it is preferable that the thickness of the metal plate 40 is the same as the thickness of the desired conductive path 40A. With this configuration, the second etching step can be omitted, and the pressing step, the dividing step, the mold, and the like can be omitted.

  (2) In this embodiment, although the circuit structure 1 showed the example applied to the DC-DC converter mounted in a vehicle, it is not restricted to this. The present embodiment is applied to a method for manufacturing an arbitrary circuit structure including a circuit board on which a heat generating electronic component is mounted and a conductive path (bus bar) to which the heat generating electronic component is connected through an opening of the circuit board. it can.

DESCRIPTION OF SYMBOLS 1 ... Circuit structure 10 ... Solder resist film 20 ... Circuit board 21 ... Power semiconductor element (heat-generating electronic component)
DESCRIPTION OF SYMBOLS 23 ... 1st opening part 31 ... 1st prepreg 32 ... 2nd prepreg 33 ... 2nd opening part 40 ... Metal plate material 40A ... Conductive path 41 ... 1st conductive path (conductive path)
42. Second conductive path (conductive path)
43 ... convex part 50 ... aluminum heat sink

Claims (3)

Adhering the first prepreg to the back surface of the metal plate having a front surface and a back surface, heating and pressurizing the first prepreg, and fixing the first prepreg to the back surface of the metal plate material;
In the state where the first prepreg is fixed to the back surface of the metal plate material, a first etching step is performed to form a slit by etching the metal plate material and to form a plurality of conductive paths arranged apart from each other by the slit. When,
A first opening forming step of forming a first opening for connecting the heat generating electronic component to a corresponding conductive path on a circuit board on which the electronic component including the heat generating electronic component is mounted;
Forming a second opening having an opening area equal to or larger than the area of the first opening at the position of the second prepreg corresponding to the first opening;
The second prepreg and the circuit board are stacked in this order on the plurality of conductive paths in the order of the second prepreg and the circuit board, and the second prepreg is heated and pressurized to form the plurality of conductive paths, the second An integration step of integrating the prepreg and the circuit board;
The manufacturing method of the circuit structure including this. In the manufacturing method of the circuit composition object according to claim 1, further,
A second etching step of forming a conductive path having a convex portion that is fitted into the first opening and the second opening and connected to the heat generating electronic component by etching the plurality of conductive paths;
In the integration step, the second prepreg is heated and pressurized in a state where the convex portion is fitted into the first opening and the second opening, and the plurality of conductive paths, the second prepreg, And the manufacturing method of the circuit structure body by which the said circuit board is integrated. In the manufacturing method of the circuit composition object according to claim 1 or 2, further,
An attachment step of attaching a heat sink to the surface of the first prepreg opposite to the surface bonded to the metal plate;
Forming a solder resist film on the surface of the circuit board on which the electronic component is mounted, and
The method for manufacturing a circuit structure, wherein the first prepreg, the second prepreg, and the solder resist film have a thermal conductivity of 1 W / (mK) or more.
The manufacturing method of the circuit structure including this.

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