JPS634719B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention has a conductor circuit network of a predetermined shape on both sides of a single insulating substrate, and these conductor circuit networks are electrically connected to through-hole conductors provided in the insulating substrate. The present invention relates to a method for manufacturing a printed wiring board connected to a circuit, and its purpose is to provide a method for manufacturing a printed wiring board that can reduce the number of steps and increase mass productivity.

Generally, in order to obtain a double-sided printed circuit board, a through hole is provided in a printed circuit board with a conductive circuit network of a predetermined shape on both sides, and the conductive circuit networks on both sides are electrically connected through the through hole. Hall connection method is applied. Plating metal and conductive resin paint are used for this through-hole connection. However, when connecting through holes with plated metal, the holes formed by drilling or punching on the printed circuit board must be plated, so the walls inside the holes must be activated. There was a problem in that many processing steps were required, such as chemical plating and then electroplating. On the other hand, when making through-hole connections using conductive resin paint, the holes formed by drilling or punching on the printed circuit board must be printed, so mechanical damage to the walls inside the holes must be done. There was a problem in that many processing steps were required, such as undercoat treatment and then printing with conductive resin paint to remove scum.

The present invention solves these conventional drawbacks, and uses a printed circuit board in which a conductor layer is uniformly formed on one side and through holes are provided at predetermined locations. In the step of forming an etching-resistant resin layer for forming a conductor network of a predetermined shape on the conductor layer, an etching-resistant resin layer is three-dimensionally provided in the through hole of the printed circuit board, and the etching-resistant resin layer is three-dimensionally provided in the through hole of the printed circuit board. Before removing the resin layer, a conductor circuit network of a predetermined shape is formed using conductive resin paint on the other surface of the printed circuit board, and at the same time, the conductive network is applied to the through hole of the printed circuit board provided with the etching-resistant resin layer. This is a three-dimensional layer of resin paint. According to this manufacturing method, in the step of forming the etching-resistant resin layer on one side of the printed circuit board, an undercoat for through-hole connection is applied, and the conductive resin paint is applied to the other side of the printed circuit board. Since conductor paths for through-hole connections can be formed in the process of forming a conductor network of a predetermined shape,
It has the advantage of being able to reduce the number of double-sided printed wiring board processes and increase productivity.

Examples of the present invention will be described below.

Example 1 First, as shown in FIG. 1, a printed circuit board 3 made of a paper-based phenolic resin laminate having a uniform conductor layer 1 on one side and through holes 2 at predetermined locations was prepared. Next, as shown in FIG. 2, a metal mask 4 is placed on the conductor layer 1 side of the printed circuit board 3, and an etching resist 5 is printed on the surface of the conductor layer 1 and the through holes 2 by screen printing. did. At this time, the metal mask 4 has mask holes 6 for forming a conductor network of a predetermined shape on the conductor layer 1 of the printed circuit board 3, and stepped holes corresponding to the through holes 2 of the printed circuit board 3. A mask provided with holes 7 was used, and UE manufactured by Sanwa Chemical Industries Co., Ltd. was used as the etching resist 5.
-100 was used. Then, as shown in FIG. 2, by this screen printing, a layer of etching resist 5 for a conductor circuit network of a predetermined shape is printed on the conductor layer 1 of the printed circuit board 3, and at the same time, the through holes of the printed circuit board 3 are printed. A layer of etching resist 5 was three-dimensionally printed on 2. After this printing, the printed layer of the etching resist 5 was cured by air drying so as to have contact properties. Next, the printed circuit board 3 was turned over, a metal mask 8 was placed on the other side as shown in FIG. 3, and a conductive resin paint 9 was printed by screen printing. At this time, the metal mask 8 serves as a mask hole 10 for forming a conductive circuit network of a predetermined shape on the other surface of the printed circuit board 3 on which there is no conductor layer, and the printed circuit board 3
A stepped mask hole 11 for forming an eyelet-shaped conductor path corresponding to the through hole is used,
As the conductive resin paint 9, a silver powder-resin type 5504 manufactured by DuPont, USA was used. Then, as shown in FIG. 3, by this screen printing, a layer of conductive resin paint 9 for forming a conductor circuit network of a predetermined shape is printed on the other side of the printed circuit board 3 on which there is no conductor layer, and at the same time, the etching resist is printed. Three-dimensional printing of conductive resin paint 5 for a stop-shaped conductor path was carried out in the through hole 2 of the printed circuit board 3 having the printing layer 5. After this printing, the printed circuit board 3 was placed in an electric furnace, and the printed layers of the etching resist 5 and the conductive resin paint 9 were cured at 150° C. for 30 minutes.
Thereafter, the printed circuit board 3 is etched in an etching solution of ferric chloride or cupric chloride so that the conductor layer 1 becomes a conductor network in a predetermined shape, and then immersed in a 3% weak alkaline solution for 10 minutes. Then, the printed layer of the etching resist 5 remaining on the conductor layer 1 of the printed circuit board 3 was removed. At this time, the layer of etching resist 5 printed in the through hole 2 of the printed circuit board 3 remains without being etched because it is covered with the printed layer of the conductive resin paint 9. The paint 9 acts as an undercoat for the through-hole conductor tracks. In this way, as shown in FIG. 4, a double-sided printed wiring board was obtained, which had conductor networks of a predetermined shape on both sides, and these conductor networks were electrically connected through through-hole conductor paths.

Example 2 First, as shown in FIG. 5, a printed circuit board 3 made of a paper-based phenolic resin laminate having a uniform conductor layer 1 on one side and through holes 2 at predetermined locations was prepared. Next, a layer of photopolymer (for example, 3015 manufactured by DuPont, USA) is applied to the surface of the printed circuit board 3 and the wall surface of the through hole 2, and then exposed to light.
A developing operation is performed to form a layer of etching resist 21 for a conductor circuit network of a predetermined shape on the conductor layer 1 of the printed circuit board 3 as shown in FIG. A layer of resist 21 was provided. Next, the printed circuit board 3 was turned over, a metal mask 22 was placed on the other side as shown in FIG. 7, and a conductive resin paint 23 was printed by screen printing. At this time,
The printed circuit board 3 is used as the metal mask 23.
A mask hole 24 for forming a conductor network of a predetermined shape on the other side without a conductor layer, and a stepped mask hole for forming a grommet-shaped conductor path corresponding to the through hole of the printed circuit board 3. 25 was used. As the conductive resin paint 23, the same one as in Example 1 was used. By this screen printing, as shown in FIG. 7, a conductive resin paint 23 for forming a conductive circuit network of a predetermined shape is printed on the other side of the printed circuit board 3 on which there is no conductive layer, and at the same time, the printed layer of the etching resist 21 is printed. Three-dimensional printing of conductive resin paint 23 for a stop-shaped conductor path was performed on the through hole 2 of the printed circuit board 3 having a conductor path. After this printing, the printed circuit board 3 was placed in an electric furnace, and the printed layer of the conductive resin paint 23 was cured at 150° C. for 30 minutes. Thereafter, the printed circuit board 3 is immersed in an etching solution of ferric chloride or cupric chloride to etch the conductor layer 1 into a conductor circuit network of a predetermined shape. The layer of etching resist 21 on 1 was mechanically peeled off. At this time, the layer of etching resist 21 provided in the through hole 2 of the printed circuit board 3 remains without being etched because it is covered with the printed layer of the conductive resin paint 23. 23 serves as an undercoat for the through-hole conductor tracks. In addition, conductive resin paint 23 as a through-hole conductor path
Since the three-dimensional printing layer is limited by the solder resist 21 layer, the printing range of the conductive resin paint 23 can be clearly limited. In this way, as shown in FIG. 8, a double-sided printed wiring board was obtained, which had conductor networks of a predetermined shape on both sides, and these conductor networks were electrically connected through through-hole conductor paths.

Incidentally, in the above embodiment, before the etching process according to the etching resist layer of a predetermined shape provided on the single-sided conductor layer 1 of the printed circuit board 3, the other surface of the printed circuit board 3 and the above-mentioned one on which the etching resist layer is provided are etched. Although the conductive resin paint was printed on the printed circuit board 3, the process of printing the conductive resin paint may be performed after the etching process as long as it is before the process of removing the etching resist layer. be.

As described above, according to the present invention, a conductor network of a predetermined shape can be formed on a single-sided conductor layer of a printed circuit board in which a conductor layer is uniformly provided on one side and through-holes are provided at predetermined locations. In the step of forming an etching-resistant resin layer, an etching-resistant resin layer is simultaneously provided three-dimensionally in the through hole of the printed circuit board, and before the etching-resistant resin layer is removed, a conductive layer is formed on the other surface of the printed circuit board. At the same time as forming a conductive circuit network of a predetermined shape using the conductive resin paint, a layer of the conductive resin paint is three-dimensionally formed in the through hole of the printed circuit board provided with the etching-resistant resin layer. It is possible to streamline the process of double-sided printed wiring boards and increase productivity. In particular, when forming the conductive resin paint on the through-hole for the through-hole connection, the etching-resistant resin layer exists as an undercoat, which improves the coating properties of the conductive resin paint.
Since a layer of conductive resin paint is formed before the etching-resistant resin layer is removed, when the conductive resin paint layer is heated and cured, the single-sided conductor layer is covered with the etching-resistant resin layer and oxidized. This has the advantage that there is no problem such as no problem with soldering to the conductor layer.

[Brief explanation of the drawing]

1 to 4 show an embodiment of the printed wiring board manufacturing method of the present invention, FIG. 1 is a sectional view of a single-sided printed circuit board as a starting material, and FIG. 2 is an explanation of the etching resist printing process. 3 is an explanatory diagram of the printing process of conductive resin paint, FIG. 4 is an explanatory diagram of the etching resist removal process, and FIGS. 5 to 8 are illustrations of other methods of manufacturing printed wiring boards of the present invention. Examples are shown; FIG. 5 is a sectional view of a single-sided printed circuit board as a starting material, FIG. 6 is an explanatory diagram of the etching resist coating process, FIG. 7 is an explanatory diagram of the conductive resin paint printing process, and FIG. The figure is an explanatory diagram of the etching resist removal process. 1... Conductor layer, 2... Through hole, 3... Printed circuit board, 4, 8, 22... Metal mask, 5, 21...
...Etching resist, 6,10,24...Mask hole, 7,11,25...Stepped mask hole,
9, 23... Conductive resin paint.

Claims (1)

[Claims] 1. A printed circuit board having a conductor layer uniformly provided on one side and through holes provided at predetermined locations, and an etching-resistant resin layer for a conductor circuit network of a predetermined shape on the conductor layer of this printed circuit board. a first step of three-dimensionally providing an etching-resistant resin layer in the through hole of the printed circuit board;
After this process, a conductive circuit network of a predetermined shape is formed using conductive resin paint on the other surface of the printed circuit board, and at the same time, a layer of conductive resin paint is three-dimensionally applied to the through hole provided with the etching-resistant resin layer. a second step, and a third step of etching the conductive layer provided with the etching-resistant resin layer including the conductive resin paint layer after the second step; A method for manufacturing a printed wiring board, characterized in that a fourth step of removing the etching-resistant resin layer remaining on the conductor layer of the printed circuit board is performed sequentially.