Method for producing copper-clad laminate

Details Method for producing copper-clad laminate Method for producing copper-clad laminate

2001-07-12

2003-04-22

Lorengo, J. A. (Department: 1734)

Adhesive bonding and miscellaneous chemical manufacture

Methods

Surface bonding and/or assembly therefor

C156S233000, C156S239000, C156S247000, C156S289000, C427S096400, C427S118000, C427S148000, C428S040900, C428S200000, C428S209000, C428S344000, C428S914000

Reexamination Certificate

active

06551433

ABSTRACT:

TECHNICAL FIELD TO WHICH THE INVENTION PERTAINS
The present invention relates to a method for producing a copper-clad laminate.
BACKGROUND ART
Conventionally, as means for attaining interlayer electrical connection between inner circuit layers contained in multilayer printed wiring boards, there have been employed, in an inner circuit layer substrate, means such as an interstitial via hole (IVH)—a type of through hole—or a blind via hole (BVH)—a cavity hole. These interlayer connection means, which enable formation of fine circuits of printed wiring boards, have been generally employed over a wide range as means for attaining high-density packaging, or mounting of devices.
A copper-clad laminate or a printed wiring board having such interlayer connection means as an interstitial via hole (IVH) or a blind via hole (BVH) is produced through a buildup process in which copper foil layers are sequentially bonded to an outer layer of a printed wiring board—serving as core material—in which formation of an inner circuit has been completed, to thereby form a copper-foil circuit layer comprising multilayers and a variety of via holes are buried within a substrate.
FIG. 9
shows a method of pressing outer copper foil layers in a build-up process for producing a copper-clad laminate having an interstitial via hole (IVH)—a through hole—and a blind via hole (BVH)—a cavity.
As shown in
FIG. 9
, in general, a through hole serving as an interstitial via hole (IVH) and a cavity serving as a blind via hole (BVH) are not filled with any matter. Thus, when a typical resin-coated copper foil is pressed in a manner as shown in
FIG. 9
, coated resin used for bonding an outer copper foil layer flows into the holes, to thereby fill the holes.
However, such resin has a thermal expansion coefficient as large as approximately ten times that of copper foil—metallic material. Thus, during a cooling step involving curing of the resin after press-forming at high temperature, the degree of shrinkage of the resin is also greater than that of substrate. As a result, the copper foil bonded to the resin is pulled toward the inside of the holes due to shrinkage force of the resin.
In addition, in recent years, the requirement for forming fine circuits has led to a tendency of reduction in thickness of an outer copper foil layer. Accordingly, the outer copper foil layer is pulled toward the substrate, to thereby form a dent at the pulled area, and a surface of a copper-clad laminate produced from such a copper foil layer may fail to remain flat. Hereinafter, the dented state is referred to as “a dent fault” (persons in the art may call the state “a dimple fault.”).
FIG. 10
shows a dent fault actually occurring in an outer copper foil layer above an interstitial via hole (IVH).
When the outer copper foil layer is partially dented as shown in
FIG. 10
, sufficient adhesion may fail to be maintained between the dented portion of the outer copper foil layer and an etching resist layer at a stage when the etching resist layer such as dry film is formed on the outer copper foil layer, exposed, and developed, so as to form an external circuit. If such a resist adhesion failure occurs, during etching of the copper foil circuit only the portion of a copper foil circuit corresponding to the adhesion failure becomes finer, as compared with the target circuit width, and in an serious case, the portion is completely dissolved, to thereby cause an open circuit. In other words, etching precision of the portions of the outer copper foil layer immediately above the formed interstitial via hole (IVH) or blind via hole (BVH) is deteriorated, to thereby lower the production yield considerably.


REFERENCES:
patent: 3936548 (1976-02-01), Konicek
patent: 5959256 (1999-09-01), Saida et al.

Affiliated with

Also associated with

Rating

Method for producing copper-clad laminate does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Method for producing copper-clad laminate, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for producing copper-clad laminate will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3086732