JPH03241787A - Formation of through-hole continuity by welding - Google Patents

Abstract

PURPOSE:To eliminate plating process and enable the process to be simplified by forming a continuity circuit pattern film at both edges of a drilled hole and by welding the pattern film from both sides for obtaining a continuity through-hole. CONSTITUTION:A drilled hole 20 is provided at a specified position of an insulation substrate 2 for enabling an adhesive 1 to be applied on both surfaces, a copper foil 4 is subjected to thermal contact bonding onto the substrate 2 for laminating the copper foil 4, thus enabling an etching resist 5 to be coated onto a par which is left as a continuity circuit of a circuit substrate and a part of the drilled hole 20 for preventing etching and then etching is made to eliminating the copper foil which is not applied. In this process. the copper foil 4 remains at a continuity circuit of the insulation substrate 2 and the drilled hole 20 and, by eliminating etching resist, the copper foil 4 which exists at both edges of the drilled hole 20 of the insulation substrate 2 is subjected to thermal contact bonding from both sides for welding. Therefore, the need for electroless and electrolytic plating is eliminated, that for investment for facilities needed for plating is eliminated, and that for the running cost is eliminated, thus resulting in cost down.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for conducting through holes in a polymer insulating substrate.

[Summary of the invention]

The present invention creates conductive through-holes in a double-sided circuit board by welding. Holes for conductive through-holes are formed at desired positions on a polymer insulating board, then copper foil is thermocompression bonded to both sides of the board, and then etched. A conductive circuit pattern is formed by this, and the copper foils at both ends of the perforation are welded using a welding terminal placed at the center of the perforation, thereby establishing electrical continuity between the through-holes. By this method, a through hole of good quality and low cost can be obtained.

[Conventional technology]

A conventional method for forming conductive through-holes is shown in the 1988 edition of Electronic Technology Monthly Magazine, June Special Edition, "All About Printed Wiring Boards," Nikkan Kogyo Shimbun, Inc., page 158. In FIG. 2, step fil shows a state in which the copper foil 4 is crimped onto the polymer insulating substrate 2. Step (2)
1 shows a step of providing a perforation hole 20 for a conductive through hole at a predetermined position on the substrate 2. Step (3) shows a step of coating the perforated hole with catalyst 11 as a pretreatment for copper plating. In step (4), the circuit board 2 coated with the catalyst 11 is plated with copper 12 by electroless or electrolytic plating. Step (5) shows the process of coating the area other than the pattern remaining as a circuit and around the perforation hole with etching resist 13 in order to form a circuit on the circuit board 2 by etching. Step (6) shows the step of etching away the copper foil 4 and copper plating 12 other than the portion coated with the etching resist 13. Step (7) shows the step of removing the etching resist. The above process was performed as a conventional technique.

[Problem to be solved by the invention]

However, the conventional through-hole forming force method requires equipment for electroless or electrolytic copper plating, consumes a large amount of chemicals in each process, and requires environmentally friendly equipment such as wastewater treatment equipment for wastewater generated during the process. The costs required for surfaces, equipment, processing chemicals, and processes became longer, resulting in higher costs. Also,
There were drawbacks such as variations in the thickness of copper plating, which adversely affected the production of fine patterns.

In order to solve the conventional drawbacks, the present invention forms a conductive circuit pattern film on both ends of a perforated hole, and welds the pattern film from both sides to obtain a conductive through hole.

[Means to solve the problem]

In order to solve the above problem, instead of copper plating, we left copper foil thermocompressed to the circuit board at both ends of the drilled hole (through hole) and formed a circuit pattern by etching. Crimp the copper foil from both sides with welding terminals and weld. Eight through holes are formed using the above method.

[Effect]

As described above, the method for forming a conductive through-hole of the present invention does not require any plating process and the process is simple, resulting in lower equipment costs and higher reliability of conductivity.

〔Example〕

Embodiments of the present invention will be described below based on the drawings. 1st
The figure is a sectional view showing the process of the present invention, and the step (1+
This is a step in which a through hole 20 is provided at a predetermined position on an insulating substrate 2 made of a polymeric material such as polyimide, and an adhesive 1 is coated on both sides of the hole. Step (2)
1 is a step in which the copper foil 4 is thermocompression bonded to the substrate 2 coated with the adhesive l, and the copper foil 4 is laminated. Step (3
) is a step of coating the portions of the circuit board that are to be left as conductive circuits and the perforated holes 20 with an etching resist in order to prevent etching. Step (
4) is an etching step for removing the copper foil not coated with etching resist. In this process, copper foil remains at the conductive circuits of the insulating substrate 2 and the perforated holes 20. Step (5) is a step of removing the etching resist for preventing etching. Step (6) is a step in which the copper foils 4 present at both ends of the perforated hole 20 of the insulating substrate 2 are thermocompressed and welded from both sides. To explain in detail, two guide holes 21 are provided in the insulating substrate 2, and a pin, which is a jig on the welding machine (not shown), is inserted into the guide holes to determine the position of the drilled hole 20 in the substrate 2. and upper and lower welding terminals 7 of the welder
．． Align position 8. Next, upper and lower welding terminals 7.8 are brought closer to each other from above and below relative to the position of the substrate 2, and the upper and lower copper foils 4 are pressed against each other while being heated. The heating method may be electrical, ultrasonic, or other heating methods. Through the above steps, a conductor circuit pattern of perforated holes (through holes) is created.

Continuous processing of the above becomes possible by combining a welder with a multi-axis welding unit.

On the other hand, insulating substrates such as polyimide are intended for materials with a thickness of 100 μm or less. This is because if the deformation amount exceeds this, when the copper foils at both ends of the perforated hole 20 are welded with a welder, the amount of deformation becomes large and the copper foil 4 breaks.

〔Effect of the invention〕

Since electroless plating and electrolytic plating are no longer required, there is no need to invest in plating, and the running costs are also eliminated, reducing costs. At the same time, since conduction is achieved by welding, the reliability of conduction is improved. It has the effect of increasing the price.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the process of the present invention, and FIG. 2 is a sectional view showing the process of the prior art. ■... Adhesive 2... Insulating substrate 4 ・ ・
・ Copper foil 5 ・ ・ ・ E-chin resist 20...Drilled hole or more

Claims (1)

[Claims] Having at least one or more perforated holes at predetermined positions,
Copper foil is thermocompression bonded to both sides of a polymer insulating board with adhesive applied to both sides, and then the insulating board is etched to form a conductor with a portion of the copper foil covering both ends of the perforated hole. A method for forming through-hole conductivity by welding, comprising forming a circuit pattern, and then welding the copper foil of the conductor circuit pattern formed at both ends of the perforated hole with a welding terminal.