JPS59198791A - 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 <Technical Field> The present invention relates to a wiring board on which wiring, etc. are formed on both the front and back sides.

<Prior art> Conventionally, in wiring boards that required wiring on both sides, through holes were opened and plated/plated to ensure continuity on both sides.
Through-hole continuity was obtained using conductive paint, etc., but
There are many restrictive conditions such as workability of drilling holes for through holes, hole diameter limits, hole patterns, etc., and there are problems with productivity.

FIG. 1 is a diagram showing the manufacturing process of a conventional wiring board in which through-pole connections are made using conductive paint.

A through pole 4 is formed in a metal foil laminate plate 3 with a gold R foil 2 pasted on a base material 1, and after a wiring pattern is formed by etching or the like (5 is an etching resist),
A conductive paint 6 such as heg paste is poured into the through-pole portion by a method such as screen printing, and then jumper wiring 7 is applied to the back side 11 of the board using the conductive paint to form a rirj easy two-layer board. It had been.

FIG. 2(1) is a manufacturing process diagram when a conductive etching resist is used as the etching resist.

If a conductive etching resist is used, when forming the wiring pattern, pour the conductive etching resist 5' into the through hole s, and after etching, form the jumper wiring 7 with conductive paint on the back side. Similarly, conductivity between the front and back surfaces can be achieved by pouring conductive paint into the through-holes.

In these methods, when forming through-hole continuity, it is necessary to take measures to prevent paint from flowing into areas where the pattern is not required.Also, in order to ensure continuity on the wall surface of the through-hole, the film thickness at the hole edge must be In addition to becoming thinner, problems tend to occur in terms of continuity reliability.

In addition, as shown in FIG. 2 (2), if the component 8 is mounted on a printed circuit board using a conductive etching resist such as carbon paste (9 is a conductive adhesive), the above In addition to the problem, due to the poor adhesion between the conductive etching resist and the metal wiring, it is not possible to obtain sufficient component connection strength, and since it is mounted on the conductive etching resist, it is difficult to install it on metal. This also causes the problem that the contact resistance value becomes high.

FIG. 3 is a manufacturing process diagram when a metal foil laminate substrate using porous material is used as the base material.

In the figure, since the material 1 is porous, a cover 10 is required on the back side during the etching process. After that, jumper wiring is layered on the back side using conductive paint 7.

In these methods, since the base material is immersed in an etching solution when forming a wiring pattern using the metal foil 2 based on an etching process, the etching solution enters through the pores 4 and the back surface of the metal foil 2 is corroded by the etching solution. Therefore, it was necessary to provide the cover 10 on the back side. This increased the number of steps and caused problems in terms of productivity. In addition to the above-mentioned problems, the use of a porous base material also poses problems such as poor adaptability to changes in wiring patterns and models.

<Object of the invention> The present invention has been made in view of the above-mentioned conventional problems, and
By forming pores only in the base material using a drilling method such as a laser beam from the back side of a substrate with wiring on one side (7), a through-hole connection can be formed at any location without restrictions. The present invention aims to provide a wiring board that can increase wiring density and obtain highly reliable connections, without requiring consideration during etching treatment since the pores are formed after the wiring pattern is formed.

<Example> FIG. 4 is a manufacturing process diagram of a wiring board according to an example of the present invention.

A wiring pattern is formed using a conductive (or insulating) etching resist 14 on a metal foil laminate board 13 in which a metal foil 12 of AfV, Cu, etc. is laminated on a base material 11, and a wiring board is created by etching. . and,
After etching, the pores 1 are etched by drilling means such as laser light.
5 is formed, and a conductive paint is applied to the back side of the base material 11 by screen printing or the like to form jumper wiring 16.

The conductive paint also enters the pores 15 of the base material 11, and the conductive paint that has entered the pores comes into direct contact with the front metal foil 12, creating a highly reliable, low-resistance through-hole connection. is obtained.

4th [J (21 is a cross-sectional view showing the configuration when a printed circuit board using a conductive etching resist such as carbon paste is used and components 18 are mounted on the back side of the board. In this case, the back side of the board Since it is possible to directly mount components on the conductive paint 16 on the side, parts 4 can be directly mounted on the conductive etching resist such as carbon paste with an adhesive or the like.
A more reliable connection can be obtained than when towing.

<Effects> As explained above, in the wiring board of the present invention, the pores are formed only in the base material from the back side of the base material on which surface wiring has been applied, using a perforating means such as a beam light, and the pores are formed only in the base material. The present invention is characterized in that a backside wiring or a backside electrode is formed which is electrically connected to the above-mentioned frontside wiring through the pores, and the present invention provides the following effects.

+1) Since fine through holes can be obtained, precise through hole connections can be made in any location.

(2) Since fine through holes can be obtained, there are no restrictions on the pattern due to holes, and it is possible to increase the wiring density.

(3) Since the through-holes are formed after pattern wiring, there is no adverse effect during etching, and flexibility is provided for pattern changes and model changes.

(4) Low resistance through-hole because it connects directly to metal wiring/wires.
Hole connections can be obtained and components with high connection strength can be mounted.

[Brief explanation of the drawing]

1, FIG. 2(1), FIG. 3, and FIG. 4 f1+ are manufacturing process diagrams, and FIG. 2(2) and FIG. 4(2) are sectional views. 1]...profiteering 12. Metal foil 13..metal foil laminate board 14. etching resist 15. pores 16. conductive paint 18.. parts agent, patent attorney, Aihiko Fukuji (and 2 others)? A2ttsu 1 (2) 4th rxl (2)

Claims (1)

[Claims] 1 Forming pores only in the base material from the back side of the base material with surface wiring using a perforating means such as a laser beam, and electrically connecting to the surface wiring through the pores of the base material. A wiring board characterized in that backside wiring or backside electrodes are formed.