JP2894496B2 - Manufacturing method of printed circuit board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION << Field of Industrial Application >> The present invention relates to a method for producing a laminated board for a printed circuit having excellent dimensional stability in each step of processing the laminated board.

<< Conventional Technology >> As a printed circuit laminate, a laminated substrate obtained by impregnating an epoxy resin into a glass nonwoven fabric as a surface layer substrate, using a glass non-woven fabric as an intermediate layer substrate, and heating and pressurizing these substrates (hereinafter referred to as composite laminate) Board) has been used in large quantities.

Laminates made of glass woven fabric only and impregnated with epoxy resin have excellent mechanical strength, dimensional stability, heat resistance, etc., and high reliability of through-hole plating. Is widely used in industrial electronic devices. However, since only a glass woven fabric is used as a base material, punching cannot be performed in a punching step, which is one of the processing steps of a printed circuit board, and drilling is a reality.

Composite laminates, on the other hand, are economically less expensive than glass woven substrate laminates and are superior in that they can be processed with punched holes. And the reliability of the through-hole plating was evaluated to be lower than that of the glass woven fabric base laminate. The reason for this is that the weight ratio of the epoxy resin, which is an organic substance, and the glass woven cloth, which is an inorganic substance, is about 40:60. In this case, it is considered that the epoxy resin mainly improves various electric performances, and the glass woven fabric improves mechanical performance such as dimensional stability of bending strength.

By the way, in general composite laminates, glass nonwoven fabric is used as a base material for the intermediate layer, and distortion during heating and pressing is more likely to occur than a laminate using a woven base material, so dimensional stability is low. There is a problem of inferiority.

<< Problems to be Solved by the Invention >> The present invention aims to make the dimensional stability at the time of processing a laminate equal to that of a laminate using a glass woven fabric base material without losing the excellent features of the conventional composite laminate. Aim.

<< Means for Solving the Problems >> In the present invention, the surface layer is made of a thermosetting resin-impregnated glass woven prepreg, and the intermediate layer is made of a thermosetting resin-impregnated glass nonwoven prepreg. A method for producing a laminated board for printed circuit, comprising simultaneously laminating and forming a copper foil having excellent elongation when heated as a metal foil when heating and pressing to obtain a metal foil-clad laminate, and after-baking the laminate. .

<< Operation >> The conventional composite laminate has a problem that the dimensional stability in the laminate processing step is inferior to the laminate of the glass woven fabric base because the glass nonwoven fabric is used as the base material of the intermediate layer. . The present invention solves these drawbacks, and the use of a metal foil having an excellent elongation rate during heating and the after-baking treatment of the obtained laminated board can easily eliminate distortion during hot press molding. As a result, the dimensional stability can be improved to the same level as a glass woven fabric base laminate.

In the present invention, a copper foil (hereinafter, referred to as an HTE foil) having an excellent elongation rate when heated is used as the metal foil.

Usually, the copper foil used for the copper-clad laminate is an electrolytic copper foil.
The elongation percentage of this copper foil when heated is relatively small, and the elongation percentage at 180 ° C. is 5% or less per 10 μm thickness, 10 to 15% for 35 μm thick copper foil, and 5 to 10% for 18 μm thick copper foil. It is.

In the HTE foil used in the present invention, the crystal structure changes at a high temperature and a large elongation is maintained.

The elongation percentage of HTE foil is 180 ° C and 5.
It is at least 5%, preferably at least 7%. At 5.5% or less, there is little difference from the conventional copper foil, and the effect of improving the dimensional stability of the laminate is small. 19-30% for 35μm thick copper foil, and 18μm thick copper foil
The elongation is about 10-20%.

In the present invention, the dimensional stability of the composite laminate is improved by utilizing the features of the HTE foil by performing after-baking on the composite laminate together with the use of the HTE foil and forming.

<< Examples >> Next, the present invention will be described with reference to Examples and Comparative Examples.

Example The composition of the epoxy resin varnish is as follows.

The above materials were mixed to produce a uniform varnish.

Next, the varnish blended for the surface layer was impregnated and dried in a glass woven fabric (WE-18K-RB84 manufactured by Nitto Boss) so that the resin content was 42 to 45%, to obtain a glass woven fabric prepreg.

Subsequently, an inorganic filler having the following composition was added to the varnish similarly prepared for the intermediate layer with respect to 100 parts of the resin component, followed by stirring and mixing to prepare a varnish containing an inorganic filler.

Silica (Crystalite VX-3 manufactured by Tatsumori) 25 parts Aluminum hydroxide (Al ₂ O ₃ · 3H ₂ O) 70 parts Ultra fine powder silica (Carplex manufactured by Shionogi Pharmaceutical Co., Ltd.) 5 parts This varnish containing an inorganic filler is made of glass non-woven fabric The content of resin and inorganic charged heavy electric agent is 90
% To obtain a prepreg.

A glass non-woven fabric prepreg is used as an intermediate layer, and the glass woven prepreg is disposed on the upper and lower surface layers, and a 35 μm-thick HTE foil (elongation at 180 ° C .: 23%) is further laminated thereon. laminated molded for 90 minutes at 60 kg / cm ^2, thickness
A 1.6 mm copper-clad laminate was obtained.

Further, after-baking treatment was performed at 140 ° C to 180 ° C.

COMPARATIVE EXAMPLE In the above Examples 1 and 2, instead of the HTE foil,
μm thick electrolytic copper foil (TOC-180, 18 made by Furukawa Circuit Foil)
A 1.6 mm thick copper-clad laminate was obtained in the same manner as in Examples 1 and 2, except that the obtained copper-clad laminate was not subjected to after-baking, using an elongation percentage at 0 ° C. of 13%. Was.

The dimensional change rate (shrinkage rate) of the obtained copper-clad laminate in the process of processing it into a circuit board was measured.

 Table 2 shows the results.

As is clear from Table 2, the copper-clad laminate according to the example using the HTE foil has excellent dimensional stability.

<< Effects of the Invention >> The laminated board according to the present invention is obtained by integrally forming an HTE foil with excellent elongation when heated and a base material and performing a baking treatment, so that the dimensional stability is significantly larger than that of a conventional composite laminated board. This is equivalent to a glass woven substrate laminate and is suitable as an industrial production method of a printed circuit laminate.

In addition, the obtained laminate has improved deformation such as warpage and twist.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-62-292428 (JP, A) JP-A-62-37152 (JP, A) JP-A-55-53498 (JP, A) JP-A-59-53498 70518 (JP, A) JP-A-63-69625 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B32B 15/08 105 B32B 15/08 J B32B 31/26

Claims (1)

(57) [Claims] The surface layer is made of a glass woven fabric impregnated with a thermosetting resin, and the intermediate layer has a filler to the thermosetting resin.
On a laminated board made of glass non-woven fabric impregnated with a resin containing 10 to 200% by weight, a copper foil with an elongation at 180 ° C of 5.5% or more per 10 μm thickness is bonded as a metal foil to form a printed circuit. A method for producing a printed circuit board, comprising performing after-baking after laminate molding.