JPH01196339A - Preparation of copper-clad laminate sheet - Google Patents

Abstract

PURPOSE:To suppress the occurrence of warp due to moisture absorption in a long-term conservation, by using selectively a prepreg containing more vanish resin than inner prepreg as the outermost prepreg which becomes laminate face among a plural number of prepregs, laminating and heat-pressing it. CONSTITUTION:Craft paper weighing 135g/m is coated and impregnated with fire-retardant phenolic resin composition by a coating machine, so that the vanish resin content therein is 50%, and dried to be an inner prepreg. Next, craft paper weighing 135g/m is coated and impregnated with a water-soluble phenolic resin composition, so that the resin content therein is 105, predried and then further coated and impregnated with fire-retardant phenolic resin so that the total resin content after predrying is 52%, heated and dried to be the outermost prepreg which becomes laminate face. Seven inner prepregs are laminated on the outermost prepreg, an adhesive copper foil 1 is laid thereon, and they are heated and pressed to obtain a 1.6mm-thick fire-retardant paper phenol copper-clad laminate.

Description

DETAILED DESCRIPTION OF THE INVENTION [Purpose of the Invention (Industrial Field of Application) The present invention relates to a method for manufacturing a copper-clad laminate that is less likely to warp during long-term storage.

(Prior Art) In recent years, automation and speed-up have rapidly progressed in the processing and mounting processes of consumer printed wiring boards.

In other words, in the processing process, printing and punching presses are being automated, and the mounting of discrete components and chip components is also becoming automated and faster.

In order to carry out such a process smoothly, it is required that the printed wiring board has little warpage and good dimensional accuracy.The allowable range for warpage is within 1.0111, and the dimensional accuracy is ±0. The required distance is within 1511m.

In order to satisfy such requirements for printed wiring boards, it is necessary that the copper-clad laminate used in the previous process has less warpage and good dimensional accuracy.

(Problems to be Solved by the Invention) By the way, when copper-clad laminates, especially paper-based copper-clad laminates, are stored for a long period of time in the state of copper-clad laminates or printed wiring boards, the state shown in FIG. 1(a) occurs. The product warped to the state shown in Figure 1(b) and was processed.

There was a problem during the implementation process. This is thought to be because the paper base material 2 swells relative to the copper foil 1 due to moisture absorption during long-term storage.

The present invention was made to solve these problems, and an object of the present invention is to provide a method for manufacturing a copper-clad laminate that suppresses the occurrence of warping due to moisture absorption during long-term storage.

[Structure of the Invention (Means for Solving the Problems) The present invention provides that if a prepreg with a higher varnish resin content than the inner prepreg is used as the outermost layer of prepreg laminated on the copper foil, the occurrence of warping due to moisture absorption is reduced. This is what was discovered.

That is, in the present invention, when manufacturing a copper-clad laminate by laminating copper foil and a plurality of prepregs and applying heat and pressure, the outermost layer of the prepreg, which becomes the laminate surface, is used as the outermost prepreg from the inner prepreg. It is characterized by using a varnish with a high resin content, laminating it, and applying heat and pressure.

The copper foil used in the present invention is preferably an electrolytically treated copper foil, which has been previously coated with an adhesive to a thickness of about 30 μm on one side.

For the inner prepreg of the prepregs used in the present invention, for example, kraft paper is coated with a varnish such as a flame-retardant phenol resin composition with a coating machine so that the resin content is 45 to 55%, and is impregnated with a predetermined amount. It can be heated and dried in advance to maintain its rheology.

The flame retardant phenol resin composition is a mixture of tung oil and phenol added and polymerized under acidic conditions and a flame retardant added thereto.

Examples of flame retardants include brominated epoxy resins, tetrabromobisphenol A, triphenyl phosphate, tricresyl phosphate, phosphorus-based flame retardants such as phosphorus-containing polyols, methoxymelamine resins, ethoxymelamine resins,
Examples include nitrogen-based flame retardants such as phenol-melamine resin condensates.

The prepreg for the outermost layer, which forms the surface of the laminate, can be prepared by coating and impregnating kraft paper with a water-soluble phenol resin composition or a phenol-melamine cocondensation resin composition to a resin content of 3 to 15%, and after pre-drying. Furthermore, a flame retardant phenolic resin composition is applied and impregnated so that the total resin content is 45 to 55%, which is higher than the inner prepreg described above.
Examples include those that have been heat-dried in advance to achieve a predetermined rheology.

Note that a water-soluble phenol resin composition is an oligomer of about 3 to 4 nuclear bodies obtained by addition polymerizing phenol and formalin in the presence of a tertiary amine, and a phenol-melamine cocondensation resin composition is a melamine resin. The above-mentioned water-soluble phenol resin composition is mixed with the initial condensate at a low temperature.

In the copper-clad laminate of the present invention, the adhesive-coated copper foil is arranged as the top layer so that the adhesive side faces the prepreg side, and the next layer is
It is obtained by placing 0 sheets of prepreg, and combining the lowermost layer with a prepreg with a higher varnish resin content and heating and pressing with a multistage press. Note that the plate thickness is adjusted by adjusting the number of prepregs combined.

(Function) Among the prepregs used in this manner, the outermost layer of prepreg is made of a material with a higher varnish resin content than the inner prepreg, so that warping during moisture absorption can be reduced.

(Example) Next, examples of the present invention will be described.

First, a flame-retardant phenol resin composition was coated and impregnated on kraft paper weighing IL 135 g/x' using a coating machine so that the varnish resin content was 50%, and dried to produce an inner prepreg.

Next, kraft paper with a weight of 1359/m' has a resin content of 10%.
After pre-drying, a flame retardant phenol resin composition was applied and impregnated so that the total resin content was 52%, and the laminate surface was heated and dried. A prepreg with the outermost layer was manufactured.

Seven sheets of inner prepreg are laminated on top of this outermost layer of prepreg, and then adhesive-coated copper foil is layered, and heated and pressed using a multi-stage press to obtain a JIS grade PP7 sheet with a thickness of 1.6111.
A flame-retardant paper phenol copper-clad laminate of F was manufactured. This copper-clad laminate was cut into a size of 330 x 250 nm, a pattern with a silver foil residual rate of about 30% was formed by etching, a printed wiring board was manufactured, and then placed at 40°C and 90% humidity to conduct wiring. The warpage of the board was measured. The warpage during the manufacturing process with the original plate at O and the warpage after a predetermined number of days under 40°C and 90% RH is calculated by adding the case where the copper foil 1 side swells as shown in Figure 2 (a), and Figure 2 ( The case where the paper base material 2 side swells as in b) is expressed as a minus in the graph of FIG.

On the other hand, a copper-clad laminate (Comparative Example 1
), adhesive-coated copper foil, and 8 sheets of the prepreg used as the outermost layer prepreg in the example (Comparative Example 2), a printed wiring board was also manufactured in the same manner as in the example. Warpage was measured at 40° C. and 90% RH. The results are shown in the graph of FIG. 3 together with Examples.

As is clear from the graph, it was confirmed that the copper-clad laminate of the example exhibited little warpage when absorbing moisture.

[Effects of the Invention] As explained above, according to the method of the present invention, the varnish resin content of the prepreg used is increased in the outermost layer, thereby obtaining a copper-clad Wt laminate with less warpage due to moisture absorption during long-term storage. be able to. Therefore, it is possible to meet the demands for automation and speeding up the processing and mounting process of printed wiring boards.

[Brief explanation of the drawing]

Figure 1(a) is a cross-sectional view of a printed wiring board immediately after processing a conventional copper-clad laminate, and Figure 1(b) shows the warping of the printed wiring board in Figure 1(a) after long-term storage. Fig. 2 is a cross-sectional view of the printed wiring board showing the direction of warpage, Fig. 3 is a cross-sectional view of the printed wiring board showing the direction of warpage, and Fig. 3 is the warpage of the copper-clad laminate of the example and comparative example. It is a graph showing the behavior of. 1...Copper foil 2...Paper base material Applicant Toshiba Chemical Co., Ltd. Agent Patent attorney Sasu Suyama −

Claims (1)

[Claims] When producing a copper-clad laminate by laminating copper foil and multiple prepregs and applying heat and pressure, the outermost layer of the prepreg, which becomes the laminate surface, has a higher varnish resin content than the inner prepreg. A method for manufacturing a copper-clad laminate, which is characterized by laminating the sheets using materials and heating and pressurizing them.