JPH0465893A - Manufacture of composite circuit board - Google Patents

Abstract

PURPOSE:To perform once heating and pressurizing work and to raise productivity by removing an unnecessary part in a state that a thick circuit conductor and a thermosetting resin-immersed sheet are laminated and temporarily adhered, laminating a copper foil for a thin film circuit conductor on the thick circuit conductor, heating, pressurizing and integrating the entirety. CONSTITUTION:A thick circuit conductor 12 and a prepreg sheet 19 formed by immersing glass cloth with thermosetting resin and semicuring it are temporarily adhered by using, for example, epoxy adhesive 27. Further, a predetermined number of the sheets 19 are laminated between the sheets 19 provided by temporarily adhering the conductors 12, and the sheets 19 are temporarily adhered to each other. The temporary adherence is conducted by using self- adhesiveness of the sheet 19. The conductor 12 is opened in this state by drilling or press punching to form a hole 33, a part corresponding to a bridge 17 is cut, and an unnecessary part of the conductor 12 is removed. Further, a copper foil 35 for a thin circuit conductor is laminated on the conductor 12 through the sheet 19, the entirety is heated and pressurized by a hot press to be integrated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a composite circuit board having thick circuit conductors and thin circuit conductors.

[Prior art]

The present inventors previously proposed a composite circuit board as shown in Figure 2 (Utility Application No. 1-136110). It has a thick circuit conductor 12 for large currents, and a thin circuit conductor 13 for small currents on the surface of the same insulating substrate 11. Note that 14 is a through hole.

Conventionally, such a composite circuit board has been manufactured as follows.

First, a W4 board for a thick circuit conductor is punched to form a punched circuit pattern 15 as shown in FIG. In the figure, 12 is a thick circuit conductor punched into a required circuit pattern, 16 is an edge frame, and 17 is a bridge connecting between adjacent thick circuit conductors 12 and between thick circuit conductors 12 and edge frame 16. , 18 are positioning holes. Each thick circuit conductor 12 is held in a desired circuit pattern by a bridge 17. When molding a thick circuit conductor into two layers, for example, the above-mentioned punched circuit pattern 15 is formed by forming the required number of Brepreg sheets (glass cloth etc. with thermosetting resin) as shown in Figure 4(a). Impregnated and semi-cured) 19 is laminated on both sides.

At this time, the surface of the punched circuit pattern 15 is subjected to a blackening treatment (
or brown treatment) to form a copper oxide layer (or cuprous oxide layer). Thereafter, the laminated structure is heated and pressed for about 2 hours using a hot press to integrate the stack, thereby forming a circuit board base 22 as shown in FIG. Next, this circuit board base 22 is drilled (or grooved) as indicated by the dotted lines, and a portion corresponding to the bridge 17 in FIG. 3 is cut.

Thereafter, as shown in FIG. fcl, copper foil 25 for a thin circuit conductor is laminated on both sides of the circuit board base 22 via a prepreg sheet 24, and the whole is heated and pressed using a hot press for about 2 hours to integrate. At this time, prepreg sheet 24
of resin flows into the bridge cut hole 23, and the bridge cut hole 23 is completely filled with resin.

Finally, a hole is formed in the through hole forming part, and the inner surface thereof is plated to form a through hole 14 as shown in FIG. This completes the composite circuit board. The insulating substrate 11 is the prepreg sheet 19
and 24 are cured.

Problem C] In the manufacturing method described above, heating and pressing using a hot press is performed for about 2 hours to form the circuit board base, and then a second heating and pressing is performed to paste the copper foil for the thin circuit conductor. It's been going for about 2 hours.

Therefore, there is a drawback that a total of about 4 hours of heating and pressing time is required, and the heating and pressing work using a hot press is required for 1 hour.
At the same time, there was a desire to develop a manufacturing method that would increase productivity.

[Means for solving problems]

The present invention provides a method for manufacturing a composite circuit board that solves the problems of the prior art as described above, and its structure includes a thick circuit conductor inside an insulating board and a thin circuit conductor on the surface. In a method for manufacturing a composite circuit board having a predetermined circuit pattern, a thick circuit conductor formed in a desired circuit pattern and a required number of thermosetting resin-impregnated sheets are laminated and temporarily bonded, and in this state, unnecessary portions of the thick circuit conductor are removed. After that, a copper foil for a thin circuit conductor is laminated on the surface of the thick circuit conductor via a thermosetting resin-impregnated sheet, and the whole is heated and pressed to integrate, and then the copper foil is pattern-etched. This is characterized by forming a thin circuit conductor.

[Effect]

In the present invention, as described above, unnecessary portions of the thick circuit conductor are removed while the thick circuit conductor and the thermosetting resin-impregnated sheet are laminated and temporarily bonded, and hot pressing is not performed at this point. After this, a copper foil for a thin circuit conductor is laminated on the surface of the thick circuit conductor via a thermosetting resin impregnated sheet,
Since the whole is heated and pressurized to be integrated, the heating and pressurizing work using the press (E7) can be done only once.

〔Example〕

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

Figures 1(a) to (el) show an embodiment of the present invention in which two thick circuit conductors and two thin circuit conductors are used. Two thick circuit conductors 12 formed in a circuit pattern are manufactured, and the surfaces thereof are subjected to blackening treatment (or browning treatment) to form a copper oxide layer (or cuprous oxide layer).Thick circuit conductor The thickness of 12 is, for example, about 0.5 to 21 mm.

This thick circuit conductor 12 and a prepreg sheet 19 made by impregnating glass cloth with a thermosetting resin and semi-curing it,
As shown in FIG. ial, temporary adhesion is performed using, for example, an epoxy adhesive 27. Further, a required number of prepreg sheets 19 are laminated between the prepreg sheets 19 to which the thick circuit conductors 12 have been temporarily bonded, and the prepreg sheets 19 are temporarily bonded to each other as shown in ff1) in the figure.

This temporary adhesion is performed using the self-adhesive properties of the prepreg sheet 19. In this state, as shown in the same figure (C1), a hole 33 is made in the thick circuit conductor 12 by drilling or press punching, and a portion corresponding to the bridge 17 shown in FIG. Remove unnecessary parts.

Furthermore, as shown in Figure 1(d), a copper foil 35 for a thin circuit conductor is laminated on the surface of the thick circuit conductor 12 via a prepreg sheet 19, and the whole is heated and pressed using a hot press to integrate it. do. The thickness of the copper foil is, for example, 70 μm.

In addition, the hot press conditions are a vacuum degree of 10 to 20 Torr.
The heating and pressurizing work takes approximately 2 hours at a maximum temperature of 180°C and a maximum pressure of 40 kg/-. The bridge cut hole 33 is completely filled with resin squeezed out from the prepreg sheet 19.

After that, the process is the same as before, and the through-hole forming part is drilled, the inner surface is plated to form the through-hole 14 as shown in Figure 1, and the copper foil 35 is pattern-etched to form a thin circuit. Once the conductor 13 is formed, a composite circuit board is completed.

The insulating substrate 11 is made by hardening the prepreg resin 19.

In the embodiments described above, a case has been described in which two layers each of thick circuit conductors and thin circuit conductors are provided, but the thick circuit conductors may have one layer or three or more layers. The same applies to thin circuit conductors.

〔Effect of the invention〕

As explained above, according to the manufacturing method of the present invention, the heating and pressing work using hot press, which requires a long time, can be done only once, which improves the productivity of composite circuit boards and reduces manufacturing costs. There is.

[Brief explanation of drawings]

Figures 1181 to fQl are cross-sectional views showing a method for manufacturing a composite circuit board according to an embodiment of the present invention, Figure 2 is a perspective view showing an example of a composite circuit board, and Figure 3 is a method for manufacturing a composite circuit board. Plan view showing the punching circuit pattern used, Figure-4
(a) to (dl) are cross-sectional views showing a conventional method for manufacturing a composite circuit board. 11: Insulating substrate 12: Thick circuit conductor 13: Thin circuit conductor 19 Nibbly preg sheet 27: Epoxy adhesive 33: Pringe cutting hole 35: Copper foil for thin circuit conductor Figure-2 Figure-3

Claims (1)

[Claims] 1. In a method for manufacturing a composite circuit board having a thick circuit conductor inside an insulating substrate and a thin circuit conductor on the surface, the thick circuit conductor is formed into a desired circuit pattern and the required number of sheets are impregnated with a thermosetting resin. The sheets are laminated and temporarily bonded, and in that state, unnecessary parts of the thick circuit conductor are removed. After that, copper foil for thin circuit conductors is laminated on the surface of the thick circuit conductor via a thermosetting resin impregnated sheet. . A method for manufacturing a composite circuit board, which comprises heating and pressurizing the whole to integrate, and then pattern-etching the copper foil to form a thin circuit conductor.