JP2534355B2 - High current circuit board manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing a circuit board through which a large current flows.

[Prior art]

On a circuit board through which a relatively large current such as a motor drive current flows, it is necessary to use a circuit conductor having a large cross-sectional area. For this reason, conventional high-current circuit boards use punched circuit conductors punched from a metal plate (copper plate, aluminum plate, etc.) of an appropriate thickness into the required circuit pattern, and place this on an insulating substrate. The integrated structure is adopted (Japanese Patent Laid-Open No.
-237495).

〔Task〕

However, in the conventional large current circuit board, in order to fix the punched circuit conductor to the insulating substrate, a method of forming a copper foil pattern on the insulating substrate and soldering the punched circuit conductor on it is adopted. Manufacturing is troublesome. In addition, since the punched circuit conductor with a relatively large thickness protrudes from the surface of the insulating substrate by the thickness of the insulating substrate, the irregularities on the surface of the circuit substrate are severe, and it is difficult to print solder resist or multilayer the circuit conductor. There is a problem.

[Means for solving the problem and its action]

To solve this, as shown in FIGS. 8 (a) and 8 (b), an insulating substrate 11 is provided with a punched circuit conductor 12 obtained by punching from a metal plate, the surface of which is the insulating substrate 11. It is desirable that the structure be embedded and fixed so as to coincide with the surface. According to the results of various studies, a high-current circuit board having such a structure is obtained by laminating a punching circuit conductor and a prepreg sheet (for example, glass cloth impregnated with epoxy resin and semi-cured), and hot-pressing this. It was confirmed that it can be produced by heating and pressurizing at.

However, when a high-current circuit board is manufactured by this method, when the prepreg sheet is softened and the resin flows when heated and pressed by a hot press, the punched circuit conductor is liable to move, which causes the punched circuit conductor to move. It was found that there was a problem that the position accuracy of was not stable.

The present invention has been made based on the above-described examination results, in which prepreg sheets of punched circuit conductors are laminated and heated and pressed by a hot press to embed the punched circuit conductors in an insulating substrate. A method of manufacturing a large-current circuit board, wherein two or more holes or protrusions are formed in the punched circuit conductor, and convex portions or concave portions corresponding to the holes or protrusions are formed on the pressing surface of the hot press. Then, while the punching circuit conductor is positioned at a predetermined position by fitting the hole or projection of the punching circuit conductor into the convex portion or the concave portion of the hot press pressing surface, heating and pressing by hot pressing are performed. It is characterized by performing.

This will ensure the positioning of the punched circuit conductor, so that the punched circuit conductor is embedded in the insulating substrate.
Moreover, it is possible to manufacture a large current circuit board in which the positions of the punched circuit conductors are stable.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

1 and 2 show an embodiment of the present invention. Sign
12 is a punched circuit conductor, 13 is a prepreg sheet for forming an insulating substrate, and 14 is a hot press. Punched circuit conductor
As shown in FIG. 1 (b), 12 is punched out from a copper plate so as to form a desired circuit pattern, and holes 15 are formed at both ends of each. Further, the hole 1 is formed on one pressing surface (lower pressing surface in the illustrated example) 14a of the hot press 14.
A convex portion 16 corresponding to 4 is formed. The other pressure surface 14b
Is flat.

First, the hole 15 of the punching circuit conductor 12 is formed in the hot press pressing surface 14a.
The punched circuit conductor (12) is fitted in the convex portion (16) and positioned at a fixed position. After laminating a required number of prepreg sheets 13 thereon, the whole is heated and pressed by a hot press 14. Since the prepreg sheet 13 is once softened and compressed, it fills the gap around the punched circuit conductor 12 and then hardens to become the insulating substrate 11 as shown in FIG. In this way, a large current circuit board in which the punched circuit conductor 12 is embedded in the insulating board 11 is obtained. Since the punched circuit conductor 12 is positioned by the fitting of the hole 15 and the convex portion 16 while being heated and pressed by the hot press 14, it does not move and has high positional accuracy.

In order to improve the adhesiveness between the insulating substrate 11 and the punched circuit conductor 12, it is preferable that the surface of the punched circuit conductor 12 be subjected to blackening treatment in advance. Further, the hole 15 of the punched circuit conductor 12 is preferably formed at a position where a through hole for mounting a component on the circuit board or connecting a lead end is formed.

3 and 4 show another embodiment of the present invention. In this embodiment, the punching circuit conductor 12 has a cylindrical projection 17 formed by burring or the like. The cylindrical protrusion 17 can be used as a through hole for mounting components. The punched circuit conductor 12 is positioned by fitting the hole 15 in the cylindrical projection 17 and the convex portion 16 of the hot press pressing surface 14a to each other, as in the above-described embodiment. An opening 18 into which the cylindrical protrusion 17 is inserted is previously formed in the prepreg sheet 13. The diameter of the opening 18 may be such that the cylindrical protrusion 17 is loosely inserted.

Further, in this embodiment, the copper foil 19 is laminated on the prepreg sheet 13, and the copper foil 19 also has the opening 21 into which the cylindrical protrusion 17 is inserted. Further, a recess 22 into which the tip of the cylindrical protrusion 17 is inserted is formed on the upper pressing surface 14b of the hot press.

As shown in Fig. 3, punching circuit conductor 12 and prepreg sheet 13
When the copper foil 19 and the copper foil 19 are laminated and heated and pressed by the hot press 14, the prepreg sheet 13 is softened, compressed, and hardened to form the insulating substrate 11 as shown in FIG. In the process, the punched circuit conductor 12 is embedded in the insulating substrate 11 and the copper foil 19 is bonded to the insulating substrate 11. Pressing surface 14b on the upper side of the hot press
The concave portion 22 is formed in that the cylindrical protrusion 17 is not pressed,
This is so that the prepreg sheet 13 can be pressed uniformly over the entire surface.

FIG. 5 shows a high current circuit board manufactured as described above. If the height H of the cylindrical projection 17 is made slightly larger than the thickness T of the circuit board finally obtained, a circuit board in which the tip of the cylindrical projection 17 projects can be obtained as shown in the figure. When the cylindrical protrusion 17 of the punched circuit conductor 12 is used as a through hole, the leg portion of the power component is usually inserted therein and tightened with screws in many cases. If the tip of the cylindrical protrusion 17 is projected as shown in the figure, the tightening force of the screw is applied only to the cylindrical protrusion 17 and is not applied to the insulating substrate 11, so that there is an advantage that the insulating substrate 11 can be prevented from being damaged.

The copper foil 19 can be used as a shield layer of a large current circuit board, or can be pattern-etched and used as a signal circuit conductor.

6 and 7 show another embodiment of the present invention. In this embodiment, a cylindrical protrusion 17 is formed on each punched circuit conductor 12 by burring or the like, and the cylindrical protrusion 17 and the recessed portion 23 formed on the lower pressing surface 14a of the hot press 14 are fitted to each other. The extraction circuit conductor 12 is positioned.

Therefore, as shown in FIG. 6, first, a copper foil 19 having openings 21 similar to those in the above-described embodiment is placed on the pressing surface 14a, and a required number of prepreg sheets 13 having openings 18 are laminated thereon. Then, the punched circuit conductor 12 is laminated thereon so that the cylindrical protrusion 17 is inserted into the openings 18 and 21. At this time the cylindrical protrusion
The tip of 17 is fitted into the recess 23. As a result, each punched circuit conductor 12 is positioned at a predetermined position.

After that, when heating and pressurizing with the hot press 14, Fig. 7
As described above, the punched circuit conductor 12 is embedded in the insulating substrate 11, and the copper foil 19 is bonded to the insulating substrate 11 to manufacture a large-current circuit substrate.

When the punching circuit conductor 12 is positioned by fitting the cylindrical projection 17 of the punching circuit conductor 12 and the recess 23 of the pressing surface 14a as in this embodiment, it is necessary to increase the height of the cylindrical projection 17. Yes, the protrusion height of the cylindrical protrusion 17 after heating and pressurization also increases,
The unnecessary portion of the protruding cylindrical protrusion 17 may be removed by cutting. In the case of cutting, it is preferable to cut so that the tip of the cylindrical protrusion slightly projects from the substrate surface.

[Effects of the Invention] As described above, according to the present invention, it is possible to manufacture a large current circuit board in which a relatively thick punched circuit conductor is embedded in an insulating substrate by a relatively simple means such as hot pressing. Moreover, since the punching circuit conductor is positioned at a fixed position on the hot pressing surface when heated and pressed by the hot press, the punching circuit conductor does not move due to the flow of the resin, There is an advantage that it is possible to manufacture a high-current circuit board in which the punching circuit conductor has a high positional accuracy.

[Brief description of drawings]

1 and 2 show an embodiment of a method for manufacturing a large current circuit board according to the present invention. FIG. 1 (a) is a sectional view before pressurization, and FIG. 1 (b) is (a). ) II line cross-sectional view, FIG.
2 is a sectional view after pressurization, FIGS. 3 and 4 are sectional views showing states before and after pressurization in another embodiment of the present invention,
FIG. 5 is a cross-sectional view of a large current circuit board manufactured thereby, and FIGS. 6 and 7 are cross-sectional views showing a state before and after pressurization in still another embodiment of the present invention. 8
(A) is a plan view showing an example of a large current circuit board, and (b) is a sectional view taken along line VIII-VIII of (a). 11: Insulating board, 12: Stamped circuit conductor, 13: Prepreg sheet, 14: Hot press, 14a ・ 14b: Pressurized surface, 15: Hole, 16: Convex part, 17: Cylindrical protrusion, 18: Opening, 19: Copper Foil, 22: recess, 23: recess.

Claims (1)

(57) [Claims] 1. A method for producing a large-current circuit board in which a punched circuit conductor and a prepreg sheet are laminated and heated and pressed by a hot press to embed the punched circuit conductor in an insulating substrate. Two or more holes or protrusions are formed in the punched circuit conductor, and a protrusion or a recess corresponding to the hole or protrusion is formed on the pressing surface of the hot press to form the hole or protrusion of the punched circuit conductor. With the punched circuit conductor positioned at a predetermined position by fitting it into the convex or concave part of the hot press surface, heat by hot press,
A method for manufacturing a high-current circuit board, which comprises applying pressure.