JPS6211298A - Formation of through hole for wiring 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 (a) Technical Field The present invention relates to a method for manufacturing a through-hole wiring board, and particularly to a method for forming through-holes.

(bl Conventional technology and its disadvantages) In the conventional method of manufacturing through-hole wiring boards, for example, a wiring pattern is first formed on both sides of the board, and then a hole is made using a drill or punch in the corresponding part of the through-hole. Through-holes have been formed by applying a plating process and/or an electrical plating process. However, with this method, a plating process is always required to form a through-hole, which means that a plating process is always required when manufacturing a wiring board. A plating process was required, which required large equipment and increased production costs.

(C1 Purpose of the Invention The purpose of the present invention is to provide a method for forming through holes without using a plating process.

(d) Structure and Effects of the Invention This invention uses a substrate without copper foil on both sides as a starting base material, makes holes in the through-hole corresponding parts of this substrate, then adheres copper foil to both sides of the substrate, Next, the hole portion is punched from above or below to form a through hole.

By configuring as described above, according to the present invention, the copper foils above and below the hole are cut together, one of the copper foils adheres closely to the wall of the hole due to its ductility, and the tip end of the other copper foil is cut. It comes into contact with the copper foil part. That is, through-holes are formed by the copper foil itself present in the hole portions during the punching process, making it possible to completely eliminate the plating process required in the conventional method.

Note that the contact area between the copper foils will be in perfect contact during the subsequent soldering process. In this way, through-holes can be easily formed without a plating process, so the equipment required for the plating process is not required when manufacturing wiring boards, making it possible to significantly reduce costs and improving the process of manufacturing wiring boards. This has the advantage that the required time is short.

(e) Embodiment FIG. 1 is a diagram showing the through-hole forming method according to the present invention in the order of steps.

(A)--A substrate 1 without copper foil on both sides is prepared as a starting base material, and holes 2 corresponding to through-holes are opened at predetermined positions on this substrate. The hole 2 can be made with a drill, punch, or the like.

(B)... After all the holes corresponding to through holes are opened, copper foil 3 is bonded to both the upper and lower surfaces of the board 1.

This adhesion can be easily performed by a known thermocompression bonding method by applying a suitable adhesive to the bonded portion of the copper foil 3 or by mixing a resin or the like that contributes to adhesion to the substrate 1.

(C)...A mold 4 with holes 6 formed in corresponding portions of the through holes is prepared, and the substrate 1 is set on it. At this time, the center of the hole 2 of the substrate 1 and the center of the hole 6 of the mold 4 are set so as to coincide with each other. Note that the diameter φ2 of the hole 6 of the mold 4 is set to be slightly smaller than the diameter φ1 of the hole 2 of the substrate 1. Next, hole 2 is punched. That is, a punch 5 is set on the upper part of the upper copper foil 3 corresponding to the hole 2, and an impact is applied from above. As a result, the upper copper foil 3 is connected to the hole 2.
When the punch 5 moves downward within the hole 2, it extends downward along the circumferential surface of the punch 5, that is, in close contact with the inner wall surface of the hole 2. The diameter of the punch 5 is set to be approximately equal to the diameter φ2 of the hole 6 of the mold 4.

Alternatively, the positions of the punch 5 and the mold 4 may be reversed to punch out from the bottom.

(D) - When the punch 5 completely penetrates the hole 2 of the board 1 and the upper and lower copper foils 3, the upper copper foil 3 is in close contact with the entire wall surface of the hole 2, and the tip of the copper foil is attached to the lower side. It comes into contact with the copper foil 3. A portion 3a of the lower copper foil 3 cut by the punch 5 and the mold 4 is released to the outside. In this state, the portion of the upper copper foil 3 cut by the punch 5 is in close contact with the entire inner wall surface of the hole 2 due to the ductility of the copper foil, and its tip is in contact with the lower copper foil 3.

(E) - This is the state when the punch 5 is removed. A complete through hole is now formed. After this, a desired circuit pattern is formed on the copper foil on both sides.

Through the above steps, through holes can be formed without using a plating process. FIG. 2 shows an enlarged view of the through-hole section. As shown in the figure, a portion indicated by A is a portion where the upper copper foil 3 and the lower copper foil 3 are in contact. Although this part is electrically conductive, it is also unstable. However, when components are mounted and soldered (soldering process), since this part is close to the board surface, it is reliably soldered and a good electrical contact is made. If the diameter of the hole 2 is φ1 and the diameter of the punch 5 is φ2, the thickness t of the copper foil inside the through hole is t=1/2 (φ1
−φ2). Further, in this example, the copper foil is in close contact with the wall surface within the hole 2, but due to the characteristics of the through hole, it may not necessarily be in close contact with the wall surface.

Therefore, the diameter φ2 of the punch 5 may be smaller than the diameter φ2 of the mold 4.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the through-hole forming method according to the present invention in order of steps. Moreover, FIG. 2 shows an enlarged view of the through-hole section. l-board, 2-hole, 3-copper foil.

Claims (1)

[Claims] (1) Using a board without copper foil on both sides as a starting base material, make a hole in the through-hole corresponding part of this board, then adhere copper foil to both sides of the board, and then connect the hole part upward or A method for forming through holes in a wiring board, characterized by forming through holes by punching from below.