JPH0358907B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for continuously producing electrical laminates with improved dimensional stability. The term "electrical laminate" as used herein refers to a metal foil-covered laminate used as a printed circuit board, and is a plate-like product with a thickness of about 0.5 to 5 mm. The performance requirements for electrical laminates are stricter than those for general-purpose laminates such as building materials, and in addition to high mechanical and electrical properties, a high degree of dimensional stability is required. For printed circuit boards, it is desirable to have boards that are less likely to expand, shrink, or warp due to repeated heating, cooling, and other treatments during processing. Furthermore, with the introduction of automatic insertion machines in recent years, the warpage of boards has come to be increasingly monitored. The present inventors have already developed a method for continuously manufacturing electrical laminates that meet these performance requirements in Japanese Patent Applications No. 54-35805, No. 35806, No. 1983, and No. 54-35806.
83239, patent application No. 89623, etc. The object of the present invention is to improve these manufacturing methods, and to provide a method for continuously and industrially manufacturing electrical laminates with better dimensional stability. That is, unsaturated polyester resin liquid is continuously impregnated into a long sheet base material, then multiple sheets are laminated, metal foil is continuously laminated, excess resin is removed, and then continuously cured. In the manufacturing method for obtaining metal foil-clad laminates, the present invention adds saturated polyester to the unsaturated polyester resin liquid used, thereby suppressing curing shrinkage during curing of the unsaturated polyester resin and further improving dimensional stability. The purpose of the present invention is to obtain a metal foil-clad laminate. The present invention will be explained in more detail below. Normally, thermosetting resins undergo volumetric contraction during curing. Among these, unsaturated polyester resins have a large shrinkage rate during curing, said to be 7 to 10%. According to the studies conducted by the present inventors, it was found that the warping characteristics and heat shrinkage characteristics of a metal foil-clad laminate have an extremely strong correlation with the curing shrinkage rate of the thermosetting resin liquid used. Therefore, by lowering the curing shrinkage rate of the thermosetting resin liquid used, it is possible to improve the so-called dimensional stability such as heat shrinkage characteristics and warp characteristics of metal foil-clad laminates. It has been revealed that by incorporating saturated polyester into the saturated polyester resin liquid, the dimensional stability of the resulting metal foil-clad laminate can be improved. Examples of the saturated polyester used in the present invention include saturated polyesters obtained by reacting acid components such as phthalic anhydride, isophthalic acid, terephthalic acid, adipic acid, and sebacic acid with glycol components such as propylene glycol and ethylene glycol. can be given. The amount of the above saturated polyester added is 3% to 25% by weight to the unsaturated polyester resin liquid to be impregnated.
A range of is desirable. If the amount added exceeds 40% by weight, although there is an effect of improving dimensional stability, the strength of the laminate decreases due to the inclusion of saturated polyester, and the toughness becomes poor. In order to maintain a balance between dimensional stability and other various properties, the most preferred addition amount was in the range of 3% by weight to 25% by weight. The saturated polyester can be added by directly adding the saturated polyester in a fluid state at room temperature, or by adding the unsaturated polyester resin dissolved or dispersed in a copolymerizable vinyl monomer in advance. The elongated sheet-like base material used in the present invention includes:
Examples include glass fiber cloth, glass nonwoven fabric, kraft paper, linter paper, asbestos cloth, etc. Before impregnating these base materials with the unsaturated polyester resin liquid containing the above-mentioned saturated polyester, various pre-impregnations can be performed as necessary. For example, as already proposed by the present inventors in Japanese Patent Application No. 53239/1984, a paper base material may be pre-impregnated with an N-methylol compound having an unsaturated bond as a functional group;
Or a mixture or condensation product of methylolmelamine and/or methylolguanamine and a higher aliphatic derivative having at least one group capable of condensing with a methylol group in the molecule, as proposed in Japanese Patent Application No. 121180/1982. Pre-impregnating the paper substrate is preferred in order to improve the properties of the product, especially its moisture absorption and water supply properties. Note that the metal foil used in the present invention includes electrolytic copper foil,
These include rolled copper foil, aluminum foil, iron foil, etc., and electrolytic copper foil is usually used for printed circuit boards. As already proposed by the present inventors in Japanese Patent Application No. 83239/1983, this metal foil is coated with an adhesive, heat treated, and then continuously bonded to a resin-impregnated base material. It is preferable to laminate and heat cure. Regarding the molding pressure during curing, it is one of the embodiments of the present invention to apply pressure to a level that does not cause excess resin to protrude, but it is possible to apply the molding pressure under substantially no pressure conditions. One of the preferred embodiments of the present invention is curing with. The metal foil-clad laminate obtained by the above method has excellent not only dimensional stability but also mechanical and electrical properties, and is widely used as a printed circuit board for electrical purposes. The present invention will be explained below with reference to Examples. Example 1 Saturated polyester synthesized from propylene glycol and adipic acid and having a molecular weight of approximately 3500 and is liquid at room temperature.
1,1-bis(t-butylperoxy) 3,3,5-trimethylcyclohexane (NOF) was added as a curing catalyst to 100 parts by weight of a commercially available unsaturated polyester resin (Polymer 6304, manufactured by Takeda Pharmaceutical). A resin liquid for single dipping was obtained by blending 1 part by weight of Perhexa 3M (manufactured by Perhexa 3M) and 0.2 part by weight of a 6% cobalt naphthenate solution as a curing aid. Kraft paper (Tomoekawa Paper MKP-150) with a thickness of 280μ, which has been pre-dried for 20 minutes at 100℃, is continuously impregnated with the resin liquid from one side using the curtain flow method, six sheets are stacked, and the epoxy resin is applied from one side of the laminate. A 35μ copper foil coated with adhesive was laminated with a 35μ cellophane film on the other side and heated at 100°C for 30 minutes. After cutting this material, heat treatment was performed at 100°C for 10 hours and at 160°C for 10 minutes to further promote curing, and finally a copper-clad laminate with a thickness of 1.6 mm was obtained.
The copper foil of the resulting laminate was removed by etching with ferric chloride solution, and the sample was cut into 1 cm square pieces. After normal adjustment, the thermal expansion and contraction rates from 23°C to 150°C were measured using Perkin Elmer. Measurement was carried out using a thermophysical tester model TMS-1 manufactured by Kawasaki. The measurement results are shown in Table 1. Example 2 The same resin liquid as in Example 1 was applied to 185μ thick glass cloth (WE18K manufactured by Nittobo Co., Ltd.) instead of kraft paper.
-BR) was impregnated with a continuous liquid from one side and stacked on top of eight sheets, and then a copper-clad laminate with a thickness of 1.6 mm was obtained under the same conditions as in Example 1. Table 1 shows the measurement results of heating expansion and contraction of the obtained samples. Comparative Examples 1 and 2 A 1.6 mm copper-clad laminate was prepared in the same manner as in Examples 1 and 2 from a commercially available unsaturated polyester resin (Polymer 6304 manufactured by Takeda Pharmaceutical Co., Ltd.) containing no saturated polyester. Comparative Example 1 uses kraft paper (Tomoekawa Paper MKP-150) as the base material.
Glass cloth (WE18K manufactured by Nitto Boseki) was used as the base material.
BS) was used as Comparative Example 2. 【table】

Claims (1)

[Scope of Claims] 1. An unsaturated polyester that contains a saturated polyester that is liquid at room temperature, that essentially does not require a drying process, and that does not substantially generate reaction by-products such as gas or liquid during the curing reaction process. An electrical laminate, characterized in that a plurality of long sheet-like substrates impregnated with a resin liquid are continuously conveyed, successively laminated, further laminated with metal foil, and then continuously cured. continuous manufacturing method. 2 Unsaturated polyester resin liquid is 3% to 25% by weight
2. A method for continuously manufacturing an electrical laminate according to claim 1, characterized in that it contains saturated polyester in an amount of % by weight.