JPH0417385A - Manufacture of compound circuit board - Google Patents

Abstract

PURPOSE:To reduce manufacture cost of a compound circuit board by forming a thick circuit conductor of a required circuit pattern in a state of being fixed to the surface of an insulating plate. CONSTITUTION:A copper-clad laminate plate 29, where a copper plate 28 for a thick circuit conductor is stuck at least on one side of an insulating plate 27, is manufactured, and the copper plate 28 is pattern-etched to form a thin circuit conductor 12. Next, blackening treatment is performed on the surface of the thick circuit conductor 12 to form a copper oxide layer 21 on the surface of the thick circuit conductor 12, and a copper foil 25 for a thin circuit conductor is laminated on both sides of an obtained inner layer circuit board 22 through prepreg sheets 24 to integrate these by heat and pressing. Later, a through hole 14 is formed, further the copper foil 25 is pattern-etched to form a thin circuit conductor 13 so as to obtain a compound circuit board.

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). This composite circuit board has a thick circuit conductor 12 for large current formed in a required circuit pattern inside an insulating substrate 11, and the same insulating substrate 1
1 has a thin circuit conductor 13 for microcurrent on the surface thereof. Note that 14 is a through hole.

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

First, a copper plate for a thick circuit conductor is punched to form a punched circuit pattern 15 as shown in FIG. 3, for example. In the figure, 12 is a thick circuit conductor punched into a required circuit pattern, 16 is a frame, and 17 is an adjacent thick circuit conductor 1.
2 and between the thick circuit conductor 12 and the edge frame 16, the bridge 18 is a positioning hole. Each thick circuit conductor 1
2 is maintained in a required circuit pattern by a bridge 17.

When forming a thick circuit conductor in two layers, for example, the above-mentioned punched circuit pattern 15 is formed using an appropriate number of prepreg sheets (glass floss etc. impregnated with thermosetting resin) as shown in Figure 4(a). Laminated on both sides of the semi-cured material (19). At this time, the surface of the punched circuit pattern 15 needs to be blackened in advance to form a copper oxide layer 21 in order to improve its adhesion to the prepreg sheet 19. Next, these are heated and pressed using a hot press to integrate them, thereby forming an inner layer circuit board 22 as shown in FIG. 2(b).

Next, this inner layer circuit board 22 is drilled (or grooved) as shown by dotted lines, and the bridge 17 portion shown in FIG. 3 is cut. This cutting exposes the cut surface of the bridge, so a second blackening process is then performed. Then, as shown in FIG. 5(e), an inner layer circuit board 22 is obtained in which the inner surface of the bridge cutting hole 23 is blackened. Next, a copper foil for a thin circuit conductor is coated on both sides of the inner layer circuit board 22 via a prepreg sheet 24. 25 are stacked and the whole is heated and pressurized to integrate.

At this time, the resin of the prepreg sheet 24 flows into the bridge cutting hole 23, and the bridge cutting hole 23 is completely sealed with the resin.

Thereafter, 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. Once formed, a composite circuit board is completed. The insulating substrate 11 is the prepreg sheet 19
and 24 are cured.

〔assignment〕

However, the manufacturing method described above requires a bridge cutting step that requires precision processing and two blackening treatment steps, so there is a problem in that the manufacturing cost increases.

[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 is composed of a copper-clad laminate in which a copper plate for a thick circuit conductor is pasted on at least one side of an insulating plate. A plate is produced, unnecessary parts of the copper plate are removed to form a thick circuit conductor with a desired circuit pattern, and after the thick circuit conductor is blackened, prepreg is applied to at least the side of the thick circuit conductor. After laminating copper foil for thin circuit conductors through sheets and integrating them by heating and pressing,
The method is characterized in that the copper foil is pattern-etched to form a thin circuit conductor.

[Effect]

In this manufacturing method, the thick circuit conductor of the desired circuit pattern is formed in a state fixed to the surface of the insulating plate, so the bridge is not required, and the cutting process of the bridge and the accompanying blackening process are also not required.

〔Example〕

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

In the manufacturing method of the present invention, first, as shown in Figure 1(a),
A copper-clad laminate 29 is manufactured by pasting a copper plate 28 for a thick circuit conductor on at least one side (both sides in this example) of an insulating plate 27. This can be manufactured by laminating copper plates 28 on both sides of an appropriate number of prepreg sheets and heating and pressing them. The thickness of the copper plate 28 is 0°1~2I! 1I11 oxygen-free copper plate, tough pitch copper plate, phosphorous deoxidized copper plate, etc. are used.

Next, the copper plate 28 is pattern-etched to form a thick circuit conductor 12 as shown in FIGS. The pattern etching is preferably carried out by printing an organic compound-based or metal-based etching resist on the surface of the copper plate 28, and performing one-way spray etching. As an etching solution, use cupric chloride or ferric chloride for organic compound resists (dry film, etc.), and for metal resists (solder, etc.).
In this case, use ammonium peroxide, alkaline etchant, etc.

Next, the surface of the thick circuit conductor 12 thus formed is subjected to a blackening treatment. This is to form a copper oxide layer 21 on the surface of the thick circuit conductor 12 using a Nap:10□/NaOH based solution.

Next, copper foils 25 for thin circuit conductors are laminated on both sides of the inner layer circuit board 22 obtained in the above manner with prepreg sheets 24 interposed therebetween, as shown in FIG. and become one. It is desirable to use a prepreg sheet 24 with a large amount of resin in order to fill the gaps between the thick circuit conductors 12.

When the thickness of the thick circuit conductor 12 is as thick as 1 mm or more, or when the circuit pattern is complicated, a thermosetting resin may be applied in advance to fill the gaps between the thick circuit conductors 12. The copper foil 25 used has a thickness of about 35 μm or 70 μm. The conditions for heating and pressurizing are generally a temperature of 170 to 180°C, a pressure of 40 to 50 kg/c+n',
The time is 2 hours.

After this, the process is the same as in the conventional method, by drilling a hole in the through-hole forming part, plating the inner surface to form a through-hole 14 as shown in FIG. 2(d), and pattern-etching the copper foil 25. By forming the thin circuit conductor 13, a composite circuit board is completed.

The insulating substrate 11 is composed of an insulating plate 27 and a prepreg sheet 24 that are cured.

In the above embodiments, the thick circuit conductor is provided on both sides of the insulating plate, but the thick circuit conductor may be provided only on one side of the insulating plate.

In addition, if the thick circuit conductor is made to have a large area by narrowing the distance between the conductors as much as possible, a composite circuit board with good thermal diffusivity can be obtained.

〔Effect of the invention〕

As explained above, according to the present invention, in the process of manufacturing a composite circuit board, there is no need for the conventional bridge cutting process, and the blackening process only needs to be done once, so the manufacturing cost of the composite circuit board can be reduced. There are advantages.

[Brief explanation of the drawing]

Figures 1(a) to 1(d) 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 conventional method for manufacturing a composite circuit board. a top view showing a punched circuit pattern used in a method for manufacturing a composite circuit board;
FIGS. 4(a) to 4(d) are cross-sectional views showing a conventional method for manufacturing a composite circuit board. 11: Insulating board 12: Thick circuit conductor 13: Thin circuit conductor 21: Copper oxide layer (blackening treatment layer) 22: Inner layer circuit board 24 Nibbly preg sheet 25: Copper foil 27: Insulating plate 28: Copper plate 29: Copper Tensioned laminate diagram-2 Figure-3

Claims (1)

[Claims] 1. A method for manufacturing a composite circuit board having a thick circuit conductor inside the insulating board and a thin circuit conductor on the surface, which includes a copper-clad laminate in which a copper plate for the thick circuit conductor is pasted on at least one side of the insulating board. After removing unnecessary parts of the copper plate to form a thick circuit conductor with a desired circuit pattern, and applying blackening treatment to the thick circuit conductor, a prepreg sheet is applied at least to the side of the thick circuit conductor. A method for manufacturing a composite circuit board, which comprises: laminating copper foil for a thin circuit conductor through a substrate, heating and pressurizing them to integrate them, and then pattern-etching the copper foil to form a thin circuit conductor.