JP3340752B2 - Manufacturing method of flexible printed wiring board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible printed wiring board used for electronic equipment and the like, and more particularly to a method for manufacturing a flexible printed wiring board requiring high-density wiring / mounting.

[0002]

2. Description of the Related Art With the increase in density of printed wiring boards used in electronic equipment and the like, the general tendency of printed wiring boards, including flexible printed wiring boards, has been to increase the number of layers using through holes and to reduce the diameter of through holes. Minimization, miniaturization of wiring patterns, etc. are being addressed.

[0003]

In a flexible printed wiring board, increasing the number of layers, reducing the pattern width, and minimizing through-hole lands are already close to their technical and processing accuracy limits. In addition, the manufacturing cost is dramatically increased, and there is a limit in increasing the density by such a method.

Accordingly, the present invention provides a flexible printed wiring board having two or more surfaces, by integrating through holes used for connection between layers and mounting lands of surface-mounted components so that the through hole lands do not occupy the substrate surface area. This is to improve the component mounting density and the pattern wiring density.

[0005]

Means for Solving the Problems The method of manufacturing a flexible printed wiring board having a through hole, through
On both sides of the through-hole wiring board so as to close the holes from both sides, the film coverlay and the hot plate press, after divided through holes and on the through-holes near the film cover lay, in the vicinity and on the through holes through-hole film
Through holes in the copper plating on and near the through-holes by performing copper plating to the portion removed coverlay
Then, land for surface mounting is formed. In addition, through hole
And remove the film coverlay near through holes
An excimer laser is used.

[0006]

According to the present invention, the through hole is filled with the adhesive of the film cover lay by the hot plate pressing step, so that the filling of the through hole and the formation of the film cover lay can be performed simultaneously. In addition, since the excimer laser is used to remove the film coverlay on the through-hole, the thickness to be removed can be easily adjusted according to the laser irradiation time, and it is processed so that it is completely the same height as the surface copper foil it can. Further, no contaminants or residues remain on the removed surface. Therefore, the density of the copper plating applied to this portion later is good, and the connection reliability is high. In laser processing, the size of the mounting land can be freely determined by masking.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The manufacturing method of the present invention will be described with reference to the drawings, taking a double-sided flexible printed wiring board as an example.

First, a double-sided flexible printed wiring board is composed of a base insulating material (for example, polyimide) 1 and copper foils 2 and 2 (FIG. 1). The through-hole 3 is processed (for example, drilled) on the double-sided flexible printed wiring board (FIG. 2). Next, in order to perform interlayer connection, electroless and electrolytic copper plating 4 is performed (FIG. 3). This substrate is etched to form a predetermined copper pattern 5 (FIG. 4).

The film cover lay is composed of a base insulating material 6 and an adhesive 7 as shown in FIG. 5, and after forming a hole in the film cover lay 8 to open a mounting land, a pattern-formed flexible printed wiring board is formed. Is hot pressed on both sides (FIG. 6). This hot press fills the through holes 9 with the adhesive of the film coverlay 8.

The processing so far is based on the prior art.

The following is the core of the present invention.

An excimer laser beam 10 is selectively irradiated by a masking 11 onto and around the through hole 9 of the flexible printed wiring board on which the film coverlay is hot pressed (FIG. 7). By adjusting the irradiation time of the excimer laser 10 to be irradiated, the insulating layer of the film coverlay 8 is removed to the same height 12 as the surface copper foil on which the copper pattern 5 is formed (FIG. 8). Next, through holes 9 are formed by electroless copper plating and electrolytic copper plating.
A land 13 for surface mounting is formed thereon (FIG. 9). The other openings 14 are mounting lands for other components, but may be masked so that copper plating is not applied in some cases.

[0013]

According to the present invention, a so-called through hole for interlayer connection can be formed on the back of the mounting land of the surface mounting component, and the mounting / wiring density can be greatly improved. In addition, since an excimer laser is used to remove the film cover lay on the through-hole, the surface of the mounting land has high smoothness, high adhesion of electroless plating, and high uniformity of electroplated copper.

[Brief description of the drawings]

FIG. 1 is a one-step cross-sectional view showing a production example of one embodiment of the present invention.

FIG. 2 is a sectional view of the same step.

FIG. 3 is a sectional view of the same step.

FIG. 4 is a sectional view of the same step.

FIG. 5 is a cross-sectional view illustrating a configuration example of a film coverlay.

FIG. 6 is a sectional view of the same step.

FIG. 7 is a sectional view of the same step.

FIG. 8 is a sectional view of the same step.

FIG. 9 is a sectional view of the same step.

[Explanation of symbols]

 Reference Signs List 8 film coverlay 9 through hole 10 excimer laser beam 13 land for surface mounting

Claims (2)

(57) [Claims] 1. A method of manufacturing a flexible printed wiring board having a through hole , wherein
Both sides in the film coverlay through hole wiring board so as to cover from the side hot plate pressing, was removed dividing the through hole and on the through-holes near the film cover lay, then
A film cover on and near the through hole
Copper plating is performed on the part from which the burley has been removed .
Forming a land for surface mounting on the through hole and in the vicinity of the through hole . 2. The method according to claim 1, further comprising : on and near the through hole.
Excimera is used to remove the film coverlay on the side
2. The flexi according to claim 1, wherein a heat sink is used.
Manufacturing method of bull print wiring board.