JPS58115885A - Method of producing circuit board - Google Patents

Abstract

(57) [Summary] 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 wiring board, and more particularly to a method of manufacturing a wiring board suitable for use in desktop computers and the like.

Conventionally, in printed circuits, a method has been used in which a copper-clad laminate or the like is photoetched to form a desired circuit pattern, and the entire surface of the conductive foil is plated with gold to prevent corrosion of the conductive foil. However, this method requires the use of expensive materials such as gold, resulting in high costs. In order to improve this, as shown in Figure 1, a circuit pattern is formed on an insulating substrate 1 by screen printing using a conductive paste 2 made of silver and synthetic resin, and then the conductive system of the circuit pattern and the entire surface of the insulating substrate are A method has been used in which a resin film 3 such as epoxy resin is overcoated to prevent corrosion of the silver film and to prevent migration of silver particles in the silver paste.

However, this method cannot be used as a solder connection or as a contact when connecting a circuit pattern to the outside because of its poor solderability, which is a major drawback of silver paste. The disadvantage was that it could not be used as a circuit contact.

Therefore, in order to improve such drawbacks, a protective film of a carbon-based conductive paint 4 was applied to the silver paste conductive circuit pattern as shown in FIGS. 1 and 2. However, this method inevitably causes some misalignment between the printed circuit pattern using silver paste and the protective film, making it difficult to sufficiently reduce the distance between the conductive foils that form the circuit pattern. There were drawbacks such as difficulty in forming many conductive strips on the circuit board.

The present invention has been made in order to eliminate the above-mentioned conventional drawbacks, and is made of a synthetic resin mixed with a silver paste forming a conductive pattern and a metal powder that is conductive only in the direction perpendicular to the substrate on the entire surface of the insulating substrate. By forming a film, the overcoat process is easy and the distance between the conductive foils can be sufficiently narrowed, eliminating the disadvantages of silver paste with poor solderability, making it especially suitable for small circuit boards without migration. The present invention provides a method for manufacturing a wiring board.

One embodiment of the present invention will be described below with reference to the drawings.
As shown in the figure, a circuit pattern is formed on an insulating substrate 1 using a conductive paste 2 made of silver and synthetic resin by screen printing or the like, and then a needle-shaped metal is placed in a suitable synthetic resin such as phenol resin or epoxy resin. A coating 5 containing powder, for example iron (Fe) powder, is printed and formed on the circuit pattern and the entire surface of the insulating substrate. In this case, in order to provide conductivity only in the vertical (vertical) direction to the board, and not to provide conductivity in the horizontal (horizontal) direction to the board, that is, to prevent connections between circuit patterns or conductive strips. In the case of iron (Fe) powder, a magnetic field is applied to provide conductivity only in the vertical direction to the substrate, while the density of the Fe powder is lowered so that there is no conduction in the horizontal direction, and the sides of the needle-shaped iron powder are It is insulated and coated with resin. In this way, even if the entire surface of the board including the circuit pattern is overcoated, the wiring pattern formed from the silver paste can be freely taken out directly from the overcoat resin as an electrode, making it suitable for circuit contacts such as small desk calculators. It can be used as

As explained above, according to the present invention, the substrate and the vertical plate are connected to each other.

All that is required is to apply a coating made of synthetic resin containing oriented metal powder that has conductivity only in the perpendicular direction to circuit patterns such as contacts and insulating substrates. Even if the conductive strips are formed, there is no horizontal conduction with the substrate, so the mutual spacing between the conductive strips can be formed sufficiently narrow, and the circuit pattern can be connected to the outside without generating migration silane between the conductive strips. This is particularly effective in providing an inexpensive wiring board suitable for circuit boards of desktop computers and the like.

[Brief explanation of the drawing]

1 and 2 are cross-sectional views showing a conventional method for manufacturing a wiring board, and FIG. 3 is a cross-sectional view showing an example of a method for manufacturing a wiring board according to the present invention. In the figure, l: insulating substrate 2: conductive paste 5: coating made of synthetic resin with oriented metal powder Patent attorney
Aihiko Fukushi Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. A method for manufacturing a wiring board, characterized in that a conductive paste forming a conductive pattern and a coating made of a synthetic resin mixed with metal powder that is conductive only in a direction perpendicular to the board are formed on the entire surface of a predetermined insulating board.