JPH0955562A - Printed wiring board - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To manufacture a rigid flex printed wiring board at low cost. SOLUTION: Printing is performed with a liquid ink on conductor circuits 12 'and 13' provided on a base film 10 to form coverlays 21 and 22. Then, the opening 31
The bonding sheets 31 and 32 having a and 32a are arranged, and further, a laminated body made of the core material 41a and the copper foil and a laminated body made of the core material 42a and the copper foil are arranged. Get the body. After forming holes in this laminated body, plating is performed to form through holes 51 and 52. Then, the outermost copper foil is etched to form the conductor circuits 41b 'and 42b'.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board, and more particularly to improvement of a cover lay laminated on the surface of a base film such as a polyimide resin on which a conductor circuit made of copper foil or the like is formed.

[0002]

2. Description of the Related Art Conventionally, a coverlay provided on a printed wiring board is formed by applying an adhesive of epoxy resin or acrylic resin on the surface of a sheet material made of polyimide resin. The laminated printed wiring boards have flexibility. A so-called rigid / flex printed wiring board is formed by laminating, for example, a rigid board having conductor circuits on both sides on a part of the flexible printed wiring board.

[0003]

As such a conventional printed wiring board, a cover lay laminated on a base film surface is used, but this printed wiring board is basically composed of a polyimide resin. Therefore, the cost of the coverlay laminating step is high, the cost of the film used for the coverlay is high, and the yield is low because the coverlay may be swollen or peeled off in the step after the coverlay is laminated. There's a problem.

The present invention solves the above problems, and an object of the present invention is to provide a printed wiring board whose manufacturing cost is suppressed as much as possible.

[0005]

A printed wiring board according to the present invention is characterized in that a coverlay is provided by printing a liquid ink on the surface of a base film having a conductor circuit formed on the surface thereof. There is.

On the surface of this coverlay, a bonding sheet having an opening laminated so as to cover the whole may be provided. Further, the liquid ink may be printed on the entire surface of the base film, or may be printed on the surface of the base film to the extent that it covers each opening provided in the bonding sheet.

The bonding sheet may be formed by impregnating a glass fiber sheet with an epoxy resin or a polyimide resin, and the liquid ink may be made of an epoxy resin or a polyimide resin as a raw material.

Further, when the bonding sheets are arranged, it is preferable that the positions of the openings provided in these bonding sheets correspond to each other.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to the illustrated embodiments. 1 to 3 show stepwise the layer structure in the manufacturing process of the printed wiring board according to the first embodiment of the present invention, and FIG. 4 shows a cross section of the layer structure of the printed wiring board. FIG. 5 shows a cross section of the layer structure of the printed wiring board according to the second embodiment of the present invention. FIG. 6 shows a cross section of the layer structure of the printed wiring board according to the third embodiment of the present invention.

The base film 10 is obtained by laminating copper foils 12 and 13 on both sides of a sheet material 11 formed of a polyimide resin or an epoxy resin,
By etching the copper foils 12 and 13, conductor circuits 12 'and 13' are formed. As the sheet material 11, a sheet material made of polyimide resin, a sheet material made of epoxy resin containing glass cloth, or a sheet material made of epoxy resin not containing glass cloth is used.

Next, as shown in FIG. 2, the base film 1
The liquid ink of polyimide resin is printed on the entire upper surface of 0. As a result, the cover lay 21 is formed. Similarly,
Printing is performed on the entire lower surface of the base film 10 using a liquid ink of polyimide resin to form a cover lay 22.

Next, the bonding sheet 31 is placed on the surface of the cover lay 21. The bonding sheet 31 has an opening 31a. Similarly, the bonding sheet 32 is arranged on the surface of the cover lay 22. The bonding sheet 32 has an opening 32.
a is provided. These openings 31a and 32a are formed at positions corresponding to each other.

Next, as shown in FIG. 3, a laminated body 41 in which a copper foil 41b is bonded onto a core material 41a is provided on the bonding sheet 31. Similarly, below the bonding sheet 32, the laminated body 42 in which the copper foil 42b is bonded onto the core material 42a is provided. Similar to the bonding sheets 31 and 32, the laminates 41 and 42 have openings 41, respectively.
c, 42c. The opening 41c is the opening 31a.
The opening 42c is formed at a position corresponding to the opening 32a. That is, the opening 41c and the opening 42c are formed at positions corresponding to each other. Laminate 41, 4
The outer shape of 2 is substantially the same as that of the base film 10 and the bonding sheets 31 and 32.

The base film 10 and the coverlay 21,
22, bonding sheets 31 and 32, and laminated body 4
1, 42 are thermocompression bonded together under a predetermined condition to form one laminated body. Next, a hole is drilled in a predetermined portion to form a hole. In this state, copper plating is applied to form through holes 51 and 52 (see FIG. 4). Then, the copper foils 41b and 42b are etched to form the conductor circuit 4
1b 'and 42b' are formed, and predetermined portions are covered with a solder resist (insulating layer).

After that, the edge portions P (see FIG. 2) of the openings 31a and 32a of the bonding sheets 31 and 32 and the laminated body 4 are formed.
The edges Q (see FIG. 3) of 1, 42 are removed, and the cover lay 2 is formed on both sides of the base film 10 as shown in FIG.
A bendable flex portion F is formed by covering Nos. 1 and 22. On both sides of the flex portion F, rigid portions R including the base film 10, the coverlays 21 and 22, the bonding sheets 31 and 32, the core materials 41a and 42a, and the conductor circuits 41b 'and 42b' are formed. That is, in this printed wiring board, the rigid portion R
Adheres the laminated bodies 41 and 42 to both sides of the same laminated body as the flex part F through the bonding sheets 31 and 32, and forms holes in the portions to be the through holes 51 and 52, and performs plating and etching. Is configured.

As described above, in this embodiment, liquid ink of polyimide resin is used as the coverlay instead of the bonding sheet. Since this liquid ink is very inexpensive, it is possible to reduce the manufacturing cost of the printed wiring board.

As the liquid ink, an epoxy resin ink may be used instead of the polyimide resin.

FIG. 5 is a sectional view of the layer structure of the printed wiring board according to the second embodiment of the present invention. In the second embodiment, the liquid ink is printed not on the entire surface of the base film 10 but on the openings 31 a, 3 of the bonding sheets 31, 32.
It is applied only to a range that sufficiently covers 2a (reference numerals 21 and 22).
The other layer structure, the material of each layer, and the effect are the same as those in the first embodiment.

FIG. 6 is a sectional view of the layer structure of the printed wiring board according to the third embodiment of the present invention. In the third embodiment, the liquid ink is printed not on the entire surface of the base film 10 but on the openings 31a, 3a of the bonding sheets 31, 32.
It is applied up to the range that covers 2a and the through holes 51 and 52 (reference numerals 21 and 22). The other layer structure, the material of each layer, and the effect are the same as those in the first embodiment.

[0020]

As described above, according to the present invention, it is possible to significantly reduce the manufacturing cost of a rigid / flex printed wiring board.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of respective sheet materials in a first stage of a process of laminating a printed wiring board which is a first embodiment of the present invention.

FIG. 2 is a perspective view showing each sheet material in a disassembled state in a second stage of the process of laminating the printed wiring board according to the first embodiment of the present invention.

FIG. 3 is an exploded perspective view showing each sheet material in a third stage of the process of stacking the printed wiring boards according to the first embodiment of the present invention.

FIG. 4 is a cross-sectional view showing the layer structure of each sheet material of the printed wiring board according to the first embodiment of the present invention.

FIG. 5 is a cross-sectional view showing the layer structure of each sheet material of the printed wiring board according to the second embodiment of the present invention.

FIG. 6 is a cross-sectional view showing the layer structure of each sheet material of the printed wiring board according to the third embodiment of the present invention.

[Explanation of symbols]

 10 Base Film 21, 22 Coverlay 31, 32 Bonding Sheet 31a, 32a, 41c, 42c Opening 41a, 42a Core Material 41b, 42b Copper Foil 51, 52 Through Hole

Claims (8)

[Claims] 1. A printed wiring board provided with a cover lay by printing a liquid ink on the surface of a base film having a conductor circuit formed on the surface thereof. 2. The printed wiring board according to claim 1, wherein a bonding sheet having an opening laminated so as to cover the entire surface of the cover lay is provided on the surface of the cover lay. 3. The printed wiring board according to claim 1, wherein the liquid ink is printed on the entire surface of the base film. 4. The printed wiring board according to claim 1, wherein the liquid ink is printed on the surface of the base film to the extent that the respective openings provided in the bonding sheet are covered. . 5. The printed wiring board according to claim 1, wherein the bonding sheet is formed by impregnating a glass fiber sheet with an epoxy resin or a polyimide resin. 6. The printed wiring board according to claim 1, wherein the liquid ink is made of an epoxy resin or a polyimide resin as a raw material. 7. The printed wiring board according to claim 1, wherein the bonding sheets are arranged such that the positions of the openings provided therein correspond to each other. 8. A base film having conductor circuits formed on both sides thereof, cover lays formed by printing liquid ink on both sides of the base film, and the surfaces of these cover lays so as to cover the entire surface thereof. And a pair of bonding sheets each having an opening laminated as described above.