JP2749685B2 - Circuit board manufacturing method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a circuit board using a relatively thick metal plate for a circuit conductor.

(Prior art)

A normal circuit board is manufactured by pattern etching a copper foil attached to the surface of an insulating board, but when relatively thick conductors are required, such as in large current circuits and power supply circuits, the A circuit board is manufactured by forming a punched circuit pattern by a punching process and laminating and integrating the same with an insulating substrate.

In this case, in order to make the positional relationship between the plurality of circuit conductors forming the circuit pattern constant, a plurality of circuit conductors forming the required circuit pattern are arranged in the frame conductor as the punched circuit pattern. A conductor in which the conductor is fixed at a fixed position by a thin bridge connecting the edge frame conductor and the circuit conductor and between adjacent circuit conductors is used. When such a punched circuit pattern and an insulating sheet such as a prepreg are laminated and integrated by hot pressing, for example, FIG.
Circuit board semi-finished products 11 as shown in FIGS. In the figure, 12 is a punched circuit pattern, 13 is an edge frame conductor, 14
Is a plurality of circuit conductors forming a circuit pattern, 15a is a bridge connecting the edge frame conductor 13 and the circuit conductor 14, 15b is a bridge connecting the adjacent circuit conductors 14 and 14, and 16 is an insulating sheet such as prepreg. Insulating substrate, 17 is the frame conductor 13
This is a positioning hole 17 formed in the portion.

After manufacturing such a semi-finished product 11, conventionally, as shown in FIG. 7, the bridge 15b between the circuit conductors 14, 14 is cut by drilling (or cutting) (18 is the hole), and furthermore, a dotted line is shown. (Between the edge frame conductor 13 and the circuit conductor 14) to cut off the surrounding edge frame conductor 13 to produce a circuit board.

In this method, a copper plate of about 0.15 to 1.6 mm can be used for the circuit conductor 14.

Although the illustrated example is a case where punched circuit patterns are embedded on both sides of an insulating substrate, one side may be a circuit pattern obtained by pattern-etching a normal copper foil. In some cases, a circuit pattern obtained by pattern-etching a copper foil is provided inside an insulating substrate.

〔Task〕

When the circuit board is manufactured by the above-described method, the obtained circuit board is such that the end face of the bridge 15a connecting the edge frame conductor and the circuit conductor is exposed on the surrounding cut surface as shown in FIG. Become. However, if the end surface of the bridge 15a is exposed on the cut surface around the circuit board in this way, when mounting the component by a reflow furnace or a jet-type soldering device, the solder adheres to the exposed portion and the circuit conductors on both surfaces are formed. There is a possibility of short-circuit, and there is a problem in reliability. There is also a problem that the corrosion of the circuit conductor easily progresses from the exposed portion of the bridge 15a.

[Means for solving the problem and its operation]

The present invention provides a method of manufacturing a circuit board that solves the above-described problems, and has a configuration in which a plurality of circuit conductors that form a required circuit pattern are arranged in an edge frame conductor, and each circuit conductor is provided. Is fixed at a fixed position with a thin bridge that connects between the frame conductor and the circuit conductor and between the adjacent circuit conductors, laminating this punched circuit pattern and the insulating sheet, and integrating them by hot pressing After doing
In a method of manufacturing a circuit board for performing a process of cutting a bridge between circuit conductors and an outer shape process of cutting off a peripheral edge frame conductor, before performing the outer shape process, cutting the bridge between the edge frame conductor and the circuit conductor In this method, the resin is filled in the holes or grooves formed by the processing.

By doing so, the end face of the bridge connected to the circuit conductor is not exposed on the cut surface around the obtained circuit board, and the conventional problem can be solved.

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

1 to 3 show one embodiment of the present invention. Figure-
The steps up to the manufacture of the semi-finished product 11 shown in FIGS. 6 (a) and 6 (b) are the same as those in the prior art. Thereafter, in the present invention, as shown in FIG. 1, the bridge 15b between the circuit conductors 14, 14 is cut. At the same time, the bridge 15a between the edge frame conductor 13 and the circuit conductor 14 is also cut. This cutting is performed by a drilling process (a cutting process or a punching process is also possible) as in the conventional case, and reference numeral 18 denotes a hole formed thereby. This hole 18 is for the bridge 15a, 15b
May be a through hole or a non-through hole as long as it is cut.
Next, as shown in FIG. 2, the resin 19 is filled into the hole obtained by cutting the bridge 15a and solidified. At this time, resin may also be filled in the hole 19 obtained by cutting the bridge 15b. After that, when the outer shape processing is performed to cut the peripheral edge frame conductor 13 by cutting along the dotted line portion, the circuit board 20 as shown in FIGS. 3A and 3B can be obtained. Since the circuit board 20 is filled with the resin 19 in the holes obtained by cutting the bridges 15a, the end surfaces of the bridges 15a are not exposed on the surrounding cut surfaces.

In actual trial production, 0.5 mm for punching circuit pattern 12
A thick copper plate was used. Further, four 0.2 mm thick prepreg sheets were used for the insulating substrate 16. The punched circuit pattern 12 was subjected to a blackening treatment in order to enhance the adhesiveness with the prepreg sheet. The hot pressing temperature 175 ° C., at a pressure 40kg / cm ^2, 1
It went for 00 minutes. The width of the bridges 15a and 15b was 1.5 mm, and the bridge was cut by drilling with a 2.3 mmφ drill. Hole 18 was filled with epoxy resin. Thereafter, the outer shape was processed, and a circuit board having a thickness of 1.5 mm without exposing the bridge end face on the surrounding cut surface was obtained.

By the way, a circuit board includes a composite circuit board having a large current circuit and a small current circuit.
As shown in FIG. 4, there has been proposed a type in which a thick circuit conductor 14 for a large current is embedded in an insulating substrate 16 and a thin circuit conductor 21 for a small current is formed on the surface of the insulating substrate (see FIG. 4). Japanese Utility Model Application No. 1-136110). Even in such a composite circuit board, since the thick circuit conductor 14 is formed from the punched circuit pattern as described above, the problem of exposing the end face of the bridge also occurs. This problem can also be solved by the manufacturing method of the present invention.

That is, as shown in FIG. 5, a composite circuit board as shown in FIG. 4 first manufactures a semi-finished product 11 in which punched circuit patterns 12 are embedded on both sides of an insulating substrate 16 and, on both sides, an adhesive layer 22 such as a prepreg. It is manufactured by laminating the laminated body of the insulating sheet 23 and the copper foil 24 through, hot-pressing with a hot press 25 to integrate the whole, and then pattern-etching the copper foil 24. Before, the bridges 15a and 15b of the semi-finished product 11 are cut by forming holes 18, for example, and then hot pressing is performed, so that the resin of the adhesive layer 22 is filled in the holes 18. Therefore, after the hot pressing, if the outer shape processing for cutting off the edge frame conductor 13 at the position of the dotted line is performed, a composite circuit board in which the bridge end surface is not exposed can be manufactured.

〔The invention's effect〕

As described above, according to the present invention, it is possible to manufacture a circuit board in which the end surface of the bridge connected to the circuit conductor is not exposed on the surrounding cut surface, so that a short circuit of the circuit conductor may occur at the cut surface during soldering of components. And the corrosion of the circuit conductor does not proceed from the cut surface, which has a remarkable effect on improving the reliability of the circuit board.

[Brief description of the drawings]

1 and 2 are plan views showing a method of manufacturing a circuit board according to one embodiment of the present invention in the order of steps, and FIGS. 3 (a) and 3 (b).
Is a plan view and a front view of a circuit board obtained thereby, FIG. 4 is a sectional view showing an example of a composite circuit board, and FIG.
Is a sectional view showing an embodiment of the present invention in the case of manufacturing the composite circuit board, and FIGS. 6A and 6B are plan views and AA of a circuit board semi-finished product in a conventional circuit board manufacturing method.
FIG. 7 is a plan view showing a conventional circuit board manufacturing method, and FIG. 8 is a front view of a circuit board obtained by the conventional manufacturing method. 11: semi-finished circuit board 12: punched circuit pattern, 13: frame conductor 14: circuit conductor, 15a, 15b: bridge 16: insulating board, 18: hole, 19: resin 20: circuit board

Claims (1)

(57) [Claims] A plurality of circuit conductors forming a required circuit pattern are arranged in an edge frame conductor, and each circuit conductor is fixed at a fixed position by a thin bridge connecting the edge frame conductor and the circuit conductor and between adjacent circuit conductors. Using the fixed punching circuit pattern,
After the punched circuit pattern and the insulating sheet are laminated and integrated by hot pressing, a circuit board manufacturing method for cutting a bridge between circuit conductors and performing outer shape processing for cutting off peripheral frame conductors. A process for cutting a bridge between the edge frame conductor and the circuit conductor before performing the outer shape processing, and filling a hole or a groove formed thereby with a resin.