JP2811995B2 - Method of manufacturing through-hole printed wiring board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a polyimide film,
The present invention relates to a method for manufacturing a so-called through-hole printed wiring board in which predetermined sections of conductive patterns provided on both front and back surfaces of an insulating substrate such as a glass epoxy resin are made conductive.

[0002]

2. Description of the Related Art Conventionally, as a method of manufacturing a through-hole printed wiring board, a method of performing through-hole plating has been adopted. That is, as shown in FIG. 6, first, copper foil 1 is bonded to both sides of an insulating substrate 3 such as a polyimide film or a glass epoxy resin by an adhesive 4, and then a through hole 5 is formed in a predetermined place. Then, FIG.
Hole 5 by electroless copper plating and electrolytic copper plating as shown in
A copper plating layer 7 is formed therein, and the copper foils 1 on the front and back surfaces are made conductive. After that, a resist such as a photoresist is applied on the copper foil 1 and etched to obtain a desired wiring pattern. The wiring pattern is provided so as to include the through hole 5, and the wiring pattern on the front and back surfaces is electrically conducted by the copper plating layer 7 attached in the hole 5.

[0003]

However, according to the above-mentioned manufacturing method, there is a disadvantage that the cost is increased due to electroless plating and electroplating, and copper by electrolytic plating adheres to the copper foil. Therefore, there is a drawback that the wiring pattern becomes thicker by itself and a wiring pattern with a narrow line spacing cannot be formed.

An object of the present invention is to solve these problems and to provide a method of manufacturing a through-hole printed wiring board which can achieve reliable conduction and has sufficient reliability.

[0005]

According to a method of manufacturing a through-hole printed wiring board of the present invention, a metal foil having a second metal layer having a lower conductivity than that of a metal foil formed on one side is provided with a through hole. Laminated so as to cover the through holes on both sides of the insulating substrate, pressing the metal foil from both sides of the through holes, deforming, connecting the upper and lower metal foils by resistance welding in the through holes, conducting, and then It is characterized in that the metal foil is etched into a predetermined wiring pattern shape.

[0006]

According to the above-described manufacturing method of the present invention, it is not necessary to electroplate the through holes of the insulating substrate, so that it is possible to reduce the cost and to form a wiring pattern with a narrow line interval. Further, since the second metal layer has a higher resistance value than the metal foil, the amount of heat generated at the connection portion increases, the amount of dissolution between the upper and lower metal foils increases, and the metal foil is further increased than in the case of the same metal foil. The connection strength between them increases.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to FIGS. First, as shown in FIG. 1, on one surface of a copper foil 1 having a thickness of 35 μm, a zinc layer 2 which is a second metal layer having a lower conductivity than the copper foil 1 is formed at 100 °. Next, as shown in FIG. 2, a 300 μm φ through-hole 5 is squeezed at a position where a through-hole is to be formed on a 25 μm-thick film-like insulating substrate 3 made of polyimide having a 20 μm-thick adhesive layer 4 formed on both sides. Set up. After a while
As shown in FIG. 3, a copper foil 1 is attached to the front and back surfaces of the insulating substrate 3 so that the second metal layer 2 faces the through holes 5. Then, as shown in FIG.
The copper foil 1 and the second metal layer 2 in the portion of the through hole 5 are pressed and bent by a heating tool having a diameter of 0 μm φ.
A current of 9 mV is passed, and the upper and lower copper foils 1 are connected by a resistance heating method. At this time, the zinc layer 2 having lower conductivity than the copper foil 1
The two members come into contact with each other, and the calorific value of the low-conductivity zinc layer 2 increases, the amount of dissolution between the upper and lower metal foils increases, and a better connection can be obtained than in the case of the same metal foil. Thereafter, as shown in FIG. 5, the conductive layers on both surfaces of the insulating substrate 3 are etched by a known method to obtain a desired wiring pattern.

[0008]

As described above, according to the present invention, the cost increase due to the plating process is reduced, and the connection can be made with stronger strength than the connection between the single metals, and a highly reliable through-hole printed wiring board can be obtained. It is obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a metal foil used in an embodiment of a method for manufacturing a through-hole printed wiring board according to the present invention.

FIG. 2 is a cross-sectional view of an insulating substrate used in an embodiment of the method for manufacturing a through-hole printed wiring board according to the present invention.

FIG. 3 is a cross-sectional view of the wiring board in one step used in one embodiment of the method of manufacturing a through-hole printed wiring board according to the present invention.

FIG. 4 is a sectional view of a wiring board in one step of an embodiment of the method for manufacturing a through-hole printed wiring board according to the present invention;

FIG. 5 is a cross-sectional view of the wiring board in another step of the embodiment of the method for manufacturing a through-hole printed wiring board according to the present invention;

FIG. 6 is a cross-sectional view of a wiring board in one step of a method of manufacturing a conventional through-hole printed wiring board.

FIG. 7 is a cross-sectional view of a wiring board in another step of a method for manufacturing a conventional through-hole printed wiring board.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 metal foil 2 second metal layer 3 insulating substrate 4 adhesive 5 through hole 6 tool 7 plating layer

──────────────────────────────────────────────────の Continuation of the front page (56) References JP-A-2-122589 (JP, A) JP-B-58-6318 (JP, B2) Printed Circuit Industry Association, Japan Printed Circuit Technology Handbook Showa Published February 28, 62, Nikkan Kogyo Shimbun, pages 250-266 (58) Fields investigated (Int. Cl. ⁶ , DB name) H05K 3 / 40,1 / 11

Claims (1)

(57) [Claims] 1. A metal foil having a conductivity lower than that of the metal foil on one side.
Forming a low second metal layer and forming a through hole in the insulating substrate;
On both surfaces, the second metal layers face each other in the through hole
After bonding with the second metal layer inside,
Using a resistance welding method from both sides of the through hole, the second
The metal layer is heated and melted to a higher temperature than the metal foil.
And bonding the two metal foils to the insulating substrate.
Of the wiring pattern formed on both sides of the
A method for manufacturing a through-hole printed wiring board, characterized in that: