JPH04268783A - Composite circuit board - Google Patents

Abstract

PURPOSE:To enable a composite circuit board to be easily manufactured and lessened in cost by a method wherein a thick-walled conductor pattern and a thin-walled conductor pattern are provided onto at least the same side of a metal board provided with an insulating layer on its circuit forming side or an insulating board. CONSTITUTION:A thick-walled circuit conductor pattern 12 and a thin-walled circuit conductor pattern 13 are formed on the same planes of both the sides of a an insulating board 11 to constitute a composite circuit board. The thick- walled circuit conductor patterns 12 formed on the sides of the board 11 are electrically connected together through a through-hole 14, and the thin-walled circuit conductor patterns 13 are electrically connected together through a through-hole 15. In this composite circuit board, as the thin-walled circuit conductor pattern 13 is formed on the surface of the insulating board 11, it can be easily subminiaturized and enhanced in density, and as the thick-walled circuit conductor pattern 12 is formed also on the surface of the insulating board 11, it can easily be formed.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite circuit board having a thick circuit conductor pattern constituting a large current power supply circuit, etc. and a thin circuit conductor pattern constituting a weak current signal circuit etc. It is something.

0002

[Prior Art] Generally, circuit boards for large currents have a thickness of approximately
Thick circuit conductors made of copper foil with a thickness of 100 μm or more are used, and thin circuit conductors made of copper foil with a thickness of several tens of μm or less are used for circuit boards for low currents, but circuits for high current and low current are combined. In the case of printed circuit boards, the following configuration is often used.

Specifically, one method is to form a pattern of thick circuit conductors 12 on both sides (or one side is possible) of an insulating substrate 11, as shown in FIG. This method forms both sides of the circuit. The other method is to laminate a thick circuit conductor 12 for large current and a thin circuit conductor 13 for weak current in different layers inside and on the surface of an insulating substrate 11, as shown in FIG. 11.

0004

[Problems to be Solved by the Invention] The former method, in which thick circuit conductors are used for all circuits, has large undercuts during pattern formation by etching, which limits the ability to reduce the conductor width and conductor spacing. It is difficult to form high-density fine circuit patterns for weak current circuits. For this reason, in the past, it was necessary to separately prepare a circuit board for high current and a circuit board for low current, which caused problems such as a large storage space being required and making it difficult to make the device compact.

[0005]Also, although it is possible to form a high-density fine circuit pattern using thin circuit conductors using a method in which thick circuit conductors and thin circuit conductors are laminated in different layers, since it is a multilayer circuit board, There are many steps such as hot pressing and positioning, and the manufacturing cost is high.

[0006]

[Means for Solving the Problems] The present invention provides a composite circuit board that solves the above-mentioned problems, and has a structure in which at least one side of an insulating substrate or a metal substrate having an insulating layer on the circuit forming surface is used. The invention is characterized in that a thick circuit conductor pattern and a thin circuit conductor pattern are formed on the same plane.

[0007]

[Operation] In this way, a high-density circuit pattern can be formed using thin-walled circuit conductors, and manufacturing is also easy because both thick-walled circuit conductors and thin-walled circuit conductors are formed on the same plane on the surface of an insulating substrate, etc. In addition, when this composite circuit board is installed in a device, there is an advantage that the storage space can be reduced.

[0008]

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an embodiment of the invention. This composite circuit board has a pattern of thick circuit conductors 12 and a pattern of thin circuit conductors 13 formed on the same plane on both sides of an insulating substrate 11. Note that 14 is the thick circuit conductor 1 on both sides.
15 is a through hole that connects the thin circuit conductors 13 on both sides. Since this circuit board has a pattern of thin circuit conductors 13 formed on the surface of the insulating substrate 11, it is easy to form a high-density fine circuit pattern, and the thick circuit conductors 12 are also formed on the surface of the insulating substrate 11. Therefore, it is easy to form.

Such a composite circuit board is shown in FIGS. 2 to 8.
It can be manufactured by the steps shown below. First, as shown in FIG. 2, a copper-clad laminate 17 is prepared in which a thick copper foil 16 having a thickness of 105 μm or more is pasted on both sides of an insulating substrate 11. Next, as shown in FIG. 3, an etching resist 18 is printed on the copper-clad laminate 17 at a position where a thick circuit conductor pattern is to be formed.

Next, this copper-clad laminate 17 is immersed in an etching solution such as cupric chloride or ferric chloride to be etched. In this etching, the resist 18 is not entirely melted away except for the printed portion, but the thin copper foil 19 is etched to a thickness of about 18 μm or 35 μm, for example, as shown in FIG.
Go to the state where remains and stop. In order to uniformly etch the thick copper foil 16 to a target thickness, the shape of the spray nozzle, oscillation mechanism, spray pressure, spray amount, etc. are controlled. Further, the target thickness can be set by controlling the eddy current value. In this etching, as shown in FIG. 4, an undercut occurs in the peripheral portion of the etching resist 18, so the etching resist 18 is printed in a slightly larger size.

Next, the etching resist 18 is peeled off, and a hole 21 is formed at the position where a through hole is to be formed, as shown in FIG.
, 22. Thereafter, burrs caused by undercutting are removed by soft etching or buffing, and the inner surfaces of the holes 21 and 22 are plated with copper to form through holes 14 and 15 as shown in FIG. 6.

Next, as shown in FIG. 7, an etching resist 23 is printed again at the positions where the thick circuit conductor pattern and the thin circuit conductor pattern are to be formed, and etching is performed.
As shown in FIG. 8, a pattern of thick circuit conductors 12 and a pattern of thin circuit conductors 13 can be formed. Thereafter, by removing the etching resist 23, a composite circuit board as shown in FIG. 1 is obtained.

Note that as a means for forming the thick copper foil 16 and the thin copper foil 19 on the surface of the insulating substrate as shown in FIG. 4, electroplating may also be considered. That is, first, a thin copper foil is formed on the entire surface of an insulating substrate by electroless plating and electroplating, and then electroplating is performed again with only the part where the thick copper foil will be formed exposed and the rest covered with an insulating resist. This method involves forming thick copper foil.

FIG. 9 shows another embodiment of the invention. This composite circuit board uses an aluminum substrate 24, an insulating layer 25 is provided on one side of the aluminum substrate 24, and a pattern of thick circuit conductors 12 and a pattern of thin circuit conductors 13 are formed on the surface thereof. . The method of forming the circuit pattern is the same as in the previous embodiment. Note that depending on the circuit board, it may be necessary to provide the thick circuit conductor 12 and the thin circuit conductor 13 consecutively as shown in the figure. It is extremely easy to manufacture.

[0015]

As explained above, according to the present invention, since the thick circuit conductor pattern and the thin circuit conductor pattern are formed on the same plane on the surface of the insulating substrate, etc., the thick circuit conductor pattern A pattern of thin circuit conductors can be formed in a series of processes, making it easy to manufacture and low cost.Also, it is possible to form a high-density, fine circuit pattern with thin circuit conductors, and the overall structure can be made compact, so storage space can be reduced. There are advantages.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of a composite circuit board according to the present invention.

FIG. 2 is a cross-sectional view showing a first step of the method for manufacturing the composite circuit board of FIG. 1;

FIG. 3 is a cross-sectional view also showing the second stage.

FIG. 4 is a cross-sectional view also showing the third stage.

FIG. 5 is a cross-sectional view also showing the fourth stage.

FIG. 6 is a sectional view also showing the fifth stage.

FIG. 7 is a cross-sectional view showing the sixth stage.

FIG. 8 is a sectional view also showing the seventh stage.

FIG. 9 is a sectional view showing another embodiment of the composite circuit board according to the present invention.

FIG. 10 is a cross-sectional view showing an example of a conventional composite circuit board.

FIG. 11 is a cross-sectional view showing another example of a conventional composite circuit board.

[Explanation of symbols]

11: Insulating board 12: Thick circuit conductor 13: Thin circuit conductor 14, 15: Through hole 24: Aluminum board
25: Insulating layer

Claims (1)

[Claims] 1. A composite circuit board characterized in that a thick circuit conductor pattern and a thin circuit conductor pattern are formed on the same plane on at least one side of an insulating substrate or a metal substrate having an insulating layer on the circuit forming surface. .