JPS6386496A - Manufacture of printed circuit board - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a printed circuit board, and in particular, it reduces overprinting of multilayer circuits by printing, prints under as smooth conditions as possible, reduces film thickness, and reduces pinholes. The present invention relates to a method of manufacturing a printed circuit board.

In the conventional manufacturing method of this type of printed circuit board, for example, when forming a multilayer circuit by printing, as shown in FIG. Requires multiple printings.

That is, the problems with such conventional technology are as follows.

1) Since overprinting is required nine times or more to form a circuit of at most two layers, the circuit reliability changes greatly depending on the positioning accuracy, which hinders the creation of fine patterns.

2) As the number of overprinting steps increases, the cost also increases.

3) More multi-layering cannot be expected.

4) In reality, it is not possible to obtain a clean printed cross-section as shown in Figure 5, and on top of that, since overprinting is performed, the surface becomes extremely uneven, making it difficult to control the film thickness and pinholes of the printed material. become unable.

The present invention solves the problems in the conventional methods, and provides a method for manufacturing printed circuit boards that reduces overprinting of multilayer circuits by printing, prints under as smooth conditions as possible, reduces film thickness, and reduces pinholes. This is what we are trying to provide.

As examples of the method of the present invention can be seen in the drawings,
In a method of manufacturing a printed circuit board in which a circuit conductor in a desired pattern is printed on an insulating substrate using conductive paste, the insulating substrate is pre-drilled with predetermined reference holes and/or through holes, and the circuit conductors are formed on at least one side of the substrate. A photosensitive resist for circuit formation is applied to the wafer, and this is exposed through a prescribed mask and developed to form circuit grooves in a prescribed pattern.
The present invention is characterized in that a conductive paste is poured directly into the circuit groove, and a circuit conductor of a desired pattern is formed by printing on the insulating substrate using the conductive paste.

That is, after drilling a reference hole and through holes 2 in an insulating substrate 1 such as a glass epoxy board or a polyimide board, a mask 4 made of photoresist 3 is formed as described above, and a conductive paste 6 is applied to this groove 5. A circuit is formed by casting using a roll coater (not shown).

Alternatively, the circuit may be formed using a metal mask. However, in this method, in order to reduce the influence of the plate spring, a UV reactive group was kneaded into the conductive paste, a circuit was formed using a metal mask as a guide, and the conductive paste was semi-cured by UV irradiation. It is preferable to remove the metal mask afterwards.

After processing one side, circuits are formed on the opposite side in the same way, and through holes are similarly formed in this process.

Note that when fitting the conductive paste 6 into the circuit groove 7 described above, voids are likely to occur in the pattern perpendicular to the direction of the squeegee or roll coater (not shown) (second
figure). Therefore, it is preferable to make the direction of the roll coater as parallel to the direction of the circuit groove 7 as possible (see FIGS. 3 and 4).

The effects of the method of the present invention are as follows.

(b) It is possible to form a circuit by minimizing the number of times of printing.

(b) Since the interlayer insulation is a base material, there are no film thickness fluctuations, voids, etc., and the electrical characteristics are stable.

(c) By forming a conductive circuit on a flat surface, the circuit film thickness can be stabilized.

(d) By forming the circuit by printing, it is easy to form the circuit.

(e) Since the mask is not a mesh screen, it has good followability to fine patterns.

(f) Through-holes can be formed at the same time as double-sided circuit formation.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the manufacturing process in one embodiment of the present invention, and FIGS. 2, 3, and 4 are respectively diagrams showing the process of forming a circuit conductor using conductive paste in one embodiment of the present invention. FIG. 5 is an explanatory diagram showing a conventional example of the manufacturing process. 1... Insulating substrate (base material) 2... Reference hole and through hole 3... Photoresist 4... Mask 5... Groove 6... Conductive paste 7... Circuit groove Patent applicant Furukawa Electric Co., Ltd. Figure 1 whistle! Figure 2 Figure 3 Figure 4;

Claims (1)

[Claims] 1. A method for manufacturing a printed circuit board in which a circuit conductor in a desired pattern is formed by printing on an insulating substrate using conductive paste, the method comprising: forming predetermined reference holes and/or through holes in the insulating substrate in advance; After drilling, a photosensitive resist for circuit formation is applied on at least one side of the substrate, and this is exposed and developed through a prescribed mask to form a circuit groove in a prescribed pattern, and a photosensitive resist for forming a circuit is applied directly to the circuit groove. 1. A method for manufacturing a printed circuit board, comprising: pouring a conductive paste into the insulating substrate, and printing a circuit conductor in a desired pattern using the conductive paste on an insulating substrate.