JPH0321095A - Manufacturing method for large electric current circuit substrate - Google Patents

Abstract

PURPOSE:To obtain a large current circuit substrate where the positional accuracy of a circuit conductor is stabilized by allowing adjoining circuit conductors to form a punched circuit pattern connected with a narrow bridge, laminating the punched circuit pattern and a prepreg sheet, and heating and pressing them with a hot press. CONSTITUTION:A plurality of circuit conductors 12 are laid out at a specified position by punching work from a conductive metal sheet. Moreover, the adjoining circuit conductors 12 from a punched circuit pattern 13 connected with a narrow bridge 15. The punched circuit pattern 13 and a prepreg sheet 19 are laminated, heated and pressed with a hot press so as to produce an intermediate for a large electric current circuit substrate with the punched circuit pattern 13 embedded on the surface of an insulation substrate 11. After the above process is over, the bridge portion of the intermediate is cut off. As described above, the adjoining circuit conductors 12 are connected with the narrow bridge 15 and positioned when they are heated and pressed with the hot press. Therefore, they will not make any relative motion due to the fluidity of resin. It is, therefore, possible to produce the large current circuit substrate where the position of the circuit conductors is stabilized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a circuit board through which a large current flows.

[Prior art]

Circuit boards that carry relatively large currents, such as motor drive currents, require the use of circuit conductors with large cross-sectional areas. For this reason, conventional high-current circuit boards use punched circuit conductors that are punched into the desired circuit pattern from a metal plate (copper plate, aluminum plate, etc.) of an appropriate thickness, and are mounted on an insulating substrate. It adopts an integrated structure (Japanese Patent Laid-Open No. 63
- Publication No. 237495).

〔assignment〕

However, conventional high-current circuit boards fix the stamped circuit conductor to the insulating board by forming a copper foil pattern on the insulating board and then soldering the stamped circuit conductor onto it. Therefore, manufacturing is troublesome. In addition, because the relatively thick punched circuit conductor protrudes from the surface of the insulating board by that thickness, the surface of the circuit board becomes uneven.
There are problems with printing solder resist and creating multiple layers of circuit conductors.

[Means for solving problems and their effects]

To solve this problem, a punched circuit conductor 12 obtained by punching a metal plate is placed on an insulating substrate 11 so that its surface is the same as the surface of the insulating substrate 11, as shown in FIG. It is desirable to have a structure in which the circuit board is embedded and fixed in a manner consistent with It was confirmed that the product could be produced by laminating the semi-cured materials and heating and pressurizing them using a press.

However, when manufacturing high-current circuit boards using this method, when heated and pressurized with a hot press, the Bripreg sheet softens and the resin flows under the pressure, which tends to cause movement of the punched circuit conductors. It was found that there was a problem in that the positional accuracy of the punched circuit conductor was unstable.

The present invention was made based on the above-mentioned inspection results, and consists of a plurality of circuit conductors arranged at predetermined positions by punching from a conductive metal plate, and adjacent circuit conductors formed into thin bridges. Connected punched circuit patterns are formed, the punched circuit patterns and Bripreg sheets are laminated, and this is heated and pressurized with a hot press to create a high current circuit with the punched circuit patterns embedded in the insulating substrate surface. This method is characterized in that after manufacturing an intermediate product of the board, the bridge portion of the intermediate product is cut.

In this way, when heating and pressurizing with the hot press, the adjacent circuit conductors are connected by the bridge and positioned relative to each other, so that they do not move relative to each other due to the flow of the resin. do not have.

Each circuit conductor becomes independent by cutting the pre-press after pressing. Therefore, it is possible to manufacture a high current circuit board in which punched circuit conductors are embedded in an insulating substrate and the positions of the circuit conductors are stable.

〔Example〕

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

In the present invention, first, a punched circuit pattern is formed by punching a copper plate. An example is shown in Figure 1. In this punched circuit pattern 13, a plurality of circuit conductors 12 are arranged in a square frame 14 to form a predetermined circuit pattern, and the circuit conductors 12 and the frame 14 are arranged between adjacent circuit conductors 12 and around the circuit conductors 12 and the frame 14. They are connected by a narrow bridge 15 between them. A hole 16 is formed in the circuit conductor 12 at a portion where a through hole will be formed later.

This punched circuit pattern 13 has one unidimensional pattern from broken line to broken line, and is repeatedly formed by punching on a continuous copper plate in the vertical direction of the paper. The edge frame 14 is formed with a feed hole 17 for feeding the copper plate during punching, and a positioning hole 18 used for positioning the punched circuit pattern l3 in a later step.

Note that the edge frame 14 is provided as necessary and may be omitted.

Next, as shown in FIG.
Layer on top of 9. In this embodiment, in order to manufacture a high current circuit board having punched circuit conductors on both sides, another punched circuit pattern 13a is laminated under the Bripreg sheet 19. After hot pressing, Buri Pregusi-1 and 19 are laminated in such a number that the required thickness can be obtained. A positioning hole 21 is also formed in advance in each Buripreg sheet 19. The punched circuit pattern 13, the Bripreg sheet 19, and the punched circuit pattern 13a are laminated with the positioning holes 18, 2l, and 18a aligned. Actually positioning holes 18, 21, 18
A positioning pin is inserted at point a, but its illustration is omitted.

Next, the laminated structure as described above is heated and pressurized using a hot press 22. Then, the Bripreg sheet 19 is once softened and compressed to fill the gap around the circuit conductor 12, and then hardened to form the insulating substrate 11 as shown in FIG. 3. In this way, an intermediate product 23 of a high current circuit board is obtained in which the punched circuit patterns 13, 13a are embedded on both sides of the insulating substrate l1. FIG. 4 is a plan view of the obtained intermediate product 23. Since the circuit conductor 12 is positioned by the bridge 15 when heated and pressurized by the photopress, it does not move and has high positional accuracy.

Note that in order to improve the adhesiveness between the insulating substrate 11 and the punched circuit patterns 13, 13a, the punched circuit patterns 13, 13
It is preferable to perform blackening treatment on the surface of a in advance.

Next, the bridge 15 part of the intermediate product 23 in Figure 4 is shown in Figure 4.
Cut the bridge 15 by punching as shown in step 5.

24 is a punched hole made by punching. By cutting the bridge 15, each circuit conductor 12 becomes independent, and the large current circuit board 25 is completed.

Note that the bridge can also be cut by cutting instead of punching.

After that, if necessary, as shown in Figure 6, a hole is drilled in the part where the upper and lower circuit conductors 12, 12a are to be electrically conductive, the inner surface is plated 26, and the solder 27 is filled to form a conductive part through which a large current can flow. Form. In addition, holes are made in the parts where power components are mounted, and cylindrical parts with flanges (like eyelets) are installed.
28 and fix it by soldering or the like. The end of this cylindrical component 28 without a flange should protrude slightly from the surface of the high current circuit board 25, so that when the leg of the power component is inserted there and tightened with screws, , the tightening force is no longer applied to the circuit board 25, and the circuit board 25
damage can be prevented.

In the above embodiments, the punched circuit pattern is provided on both sides of the insulating substrate, but the punched circuit pattern may be provided only on one side of the insulated substrate.

In that case, paste copper foil on the opposite side of the insulating board,
The copper foil can also be used as a shield layer or pattern-etched to form a signal circuit pattern.

〔Effect of the invention〕

As explained above, according to the present invention, a high current circuit board in which relatively thick circuit conductors are embedded in the insulating substrate surface can be manufactured by a relatively simple means of hot pressing. When heating and pressurizing, each circuit conductor is connected and positioned by a bridge, so it does not move due to resin flow, and there is an advantage that a high current circuit board with high positional accuracy of the circuit conductor can be manufactured.

[Brief explanation of the drawing]

Figures 1 to 6 show an embodiment of the method for manufacturing a large current circuit board according to the present invention. Figure 1 is a plan view showing an example of a punched circuit pattern, and Figure 2 is a hot press method. Figure 3 is a cross-sectional view before pressing, Figure 4 is a plan view of the intermediate high-current circuit board obtained by hot pressing, and Figure 5 is a cross-sectional view of the manufactured high-current circuit board. Floor plan, diagram-
6 is a cross-sectional view of a large current circuit board after post-processing, FIG. 7(a) is a plan view showing an example of a large current circuit board, and FIG.
bl is a sectional view taken along the line ■-■ of (al). 11: insulating substrate, 12: circuit conductor, 13: punched circuit pattern, 14: edge frame, 15: bridge, 18: positioning hole, l9: prepreg sheet, 21: Positioning hole, 22:
Hosoto Press, 23: Intermediate products for large current circuit boards, 24:
Punching hole, 25: large current circuit board. Figure-3 8a 4a Dod 4a 6a Figure-4 Figure 5

Claims (1)

[Claims] 1. By punching a conductive metal plate, a punched circuit pattern is formed in which multiple circuit conductors are arranged at predetermined positions and adjacent circuit conductors are connected by thin bridges, and this punched circuit pattern and prepreg sheet are combined. are laminated and heated and pressurized with a hot press to produce an intermediate product of a high current circuit board with a punched circuit pattern embedded in the insulating substrate surface, and then the bridge portion of the intermediate product is cut. A method for manufacturing a large current circuit board characterized by: