JPH0121566B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing an electrical copper-clad laminate. The electrical laminate refers to a laminate used for laminated insulating boards or copper-clad laminates used as substrates for various electronic components, and has a thickness of approximately 0.3 to 5 mm. Conventionally, these were paper-based phenolic resins,
It is generally manufactured from epoxy resin or the like using glass cloth as a base material. In addition, a method has been proposed in which a non-adhesive prepreg is formed using an unsaturated polyester resin varnish that is solid at room temperature and has crystallinity, and is then laminated and manufactured by pressure pressing. It has not been fully put into practical use since high school. On the other hand, when a copolymerizable monomer that is liquid at room temperature is used as a crosslinking agent and an unsaturated polyester resin that is liquid at room temperature is used, a non-adhesive prepreg cannot be formed, and in addition, it is not possible to form a non-adhesive prepreg. If an unsaturated polyester resin liquid that is liquid at room temperature is used, it is difficult to manufacture it by such conventional methods because it has high fluidity during pressure processing and is difficult to pressure mold.
Therefore, the current situation is that it has not been put into practical use at all. However, when using such an unsaturated polyester resin that is liquid at room temperature, for example, a solvent is not required in the step of impregnating the base material, and there is no need to remove any easily volatile components during the curing reaction process. Therefore, a new manufacturing method has been desired since it has the possibility of manufacturing a product that is excellent in terms of cost and is also advantageous in terms of cost. The inventors of the present invention have conducted extensive research in view of this point of view, and have found that a base material is directly impregnated with an unsaturated polyester resin liquid that is liquid at room temperature, then laminated, and then cured under no pressure conditions. The present invention was achieved by discovering that a product with excellent properties could be manufactured by using the above method. That is, the present invention
A copolymerizable monomer that is liquid at room temperature is used as a crosslinking agent. An unsaturated polyester resin liquid that is liquid at room temperature and contains aliphatic peroxides as a curing polymerization initiator is applied to the base material from one side. The method of manufacturing a copper-clad laminate for electrical use is characterized in that the impregnated base material is impregnated with a copper foil, the impregnated base material is laminated, a copper foil is laminated on at least one side, and the copper foil is then cured under pressureless conditions. Unsaturated polyester resin liquid, which is liquid at room temperature, is composed of unsaturated polyester chains synthesized from glycols, saturated dibasic acids, unsaturated dibasic acids, etc., and copolymerizable monomers, which are liquid at room temperature. It is composed of In the present invention,
Glycols include ethylene glycol, propylene glycol, diethylene glycol, etc. Saturated dibasic acids include phthalic anhydride, isophthalic acid, terephthalic acid, etc. Unsaturated dibasic acids include maleic anhydride, fumaric acid, etc., and are copolymerized. Examples of the monomer include styrene, α-methylstyrene, vinyltoluene, divinylbenzene, etc., and generally well-known unsaturated polyesters may be used. In the present invention, it is more advantageous to use an unsaturated polyester chain synthesized from propylene glycol, isophthalic acid and fumaric acid in terms of the heat resistance and dimensional stability of the product. The copolymerizable monomers may be used alone or in combination. The combined use of styrene, its monofunctional derivative, and a polyfunctional hydrocarbon monomer such as divinylbenzene is superior in terms of product dimensional stability and the like. Further, it is a desirable embodiment of the present invention that the viscosity of the resin liquid is adjusted to 0.1 to 15 poise, more preferably 0.5 to 7 poise. The viscosity is related to the ability of the resin liquid to impregnate the base material. In the present invention, the base material refers to a sheet-like base material such as paper such as linter paper or kraft paper, glass cloth, or non-woven fabric made of inorganic and organic fibers. It is important to impregnate from one side using a flow method or a squeeze roller method. In addition, it is preferable to dry the base material appropriately before impregnating it. A required number of substrates impregnated with resin liquid are laminated. A preferred lamination method in the present invention is to laminate resin-impregnated substrates impregnated with more than a predetermined amount of resin and remove excess resin liquid using a roll or blade-like object. In the present invention, this can be achieved by curing the laminate under no pressure conditions. No-pressure means that the process is carried out under normal atmospheric pressure without any artificial pressurization. Strictly speaking, as will be described later, when a film-like covering is laminated, the pressure of the weight of the covering is applied. However, in reality, such weight pressure never exceeds 0.01Kg/cm ² , and usually ranges from 0.01Kg/cm ² to 0.001Kg/cm ²
In the present invention, such a slight pressure does not impair molding conditions such as flow and outflow of the resin, and does not limit the present invention in any way. In the present invention, it is important to maintain pressure-free conditions until the resin liquid impregnated into the base material is sufficiently cured and does not show fluidity even when heated, so unnecessary pressure is avoided. may cause distortion inside the product, often resulting in unfavorable results such as dimensional stability. However, after sufficient curing, a slight pressure may be applied as necessary when performing an after-cure process, and the present invention does not limit the application of pressure at this point. Curing proceeds through a crosslinking reaction of unsaturated polyester chains with copolymerized monomers. The reaction is radical polymerization, and therefore requires the incorporation of a polymerization initiator and the need to block air. Air blocking can be easily achieved, for example, by laminating a film-like covering to the pre-cured laminate. Cellophane or polyester film (for example, Mylar) is suitable for this purpose. By using copper foil, particularly electrolytic copper foil, on one or both sides of the film-like covering, single-sided copper-clad boards and double-sided copper-clad boards can be manufactured. Organic peroxides are commonly used as polymerization initiators. Many organic peroxides for curing unsaturated polyester resins are known, but in the present invention, when a resin that is liquid at room temperature is used and a new electrical laminate is manufactured by pressureless molding, polymerization is necessary. The choice of initiator is important. In particular, in the present invention, decomposition products of organic peroxides remain in the product. Copper-clad laminates are usually heated to temperatures between 100℃ and 260℃ during the processing process.
It is often heated at various temperatures on the order of 0.degree. C., and the decomposition products mentioned above volatilize during such processing steps, sometimes producing odor. This odor impairs the working environment and is undesirable. According to the research of the present inventors,
To produce an electrical laminate with significantly reduced odor when an organic peroxide selected from aliphatic peroxides, particularly preferably aliphatic peroxyesters, is used alone or in combination. can. Aliphatic peroxides have the general formula: ROOH, RmM(OOH)n, ROOR′, RmM
(OOR)n, RnMOOMRn, R(CO ₃ H)n,
RSO ₂ OOH,

【formula】

【formula】

【formula】

[Formula] RSO ₂ OOSO ₂ R', R(CO ₃ R')n,

【formula】

【formula】

[Formula] RSO ₂ OOR′,

[Formula] (Here, R, R', R″R″ are aliphatic hydrocarbons, M is a metal or metalloid.) Specifically, for example, di-t-butylper oxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, acetyl peroxide, isobutyryl peroxide, t-butylperoxy-2-ethylhexanoate, and the like. Odor is something that people experience and there are slight differences between individuals.
It is necessary to give sufficient consideration to the evaluation method. The present inventors conducted a detailed analysis by employing multi-person odor tests, analysis of odor components using gas chromatography, and the like. The general formula of aliphatic peroxyesters is R(CO ₃ R′)n,

【formula】

【formula】

[Formula] RSO ₂ OOR' (where R and R' are aliphatic hydrocarbons, and n is an integer from 1 to 4 determined by the structure of R.), for example, t-butyl peroxyacetate. , t-butyl peroxyisobutyrate,
These include t-butylperoxy-2-ethylhexanoate and t-butylperoxylaurate. The reason why aliphatic peroxides or peroxy esters are preferred is considered to be because aromatic catalytic decomposition products are not present among the volatile components generated during heating. If aromatic organic peroxides are used, aromatic decomposition products will volatilize and cause odor. Oxide shows good results. The temperature and time conditions for curing the resin liquid vary depending on the organic peroxide used, but in the present invention, since the molding is carried out under pressureless conditions, the liquid copolymerizability in the initial stage is reduced. In order to eliminate foaming due to monomer vaporization, curing is preferably started at a temperature below 100°C, with a final temperature of 50-150°C.
A temperature range of is suitable. Copper-clad laminates are required to have advanced properties such as heat resistance, dimensional stability under heating or moisture absorption, punching properties, adhesive strength between the laminate and copper foil, and electrical insulation properties. Therefore, for the purpose of these improvements, various additives, mixtures, fillers, etc. may be added to the unsaturated polyester resin liquid at any time, and this does not limit the present invention in any way. The present invention will be described in further detail with reference to Examples below. Reference Example The resins used, their formulations, and properties are shown in Table 1.

[Table] Commercially available kraft paper (MKP-150, manufactured by Tomoekawa Paper Industries) was impregnated from one side with the resin liquid shown in Table 1 using the curtain flow method, and two sheets of this resin-impregnated paper were stacked and passed between rolls to excess. The resin liquid was removed, and at the same time, cellophane with a thickness of 25 μm was laminated on both sides. While holding this thing horizontally,
Start heating at 60℃ and reach 100℃ in 30 minutes
An electrical laminate with a thickness of 520 μm was obtained. This product was further after-cured at 85°C for 10 hours. This product had heat resistance without abnormality at 220°C for 30 minutes and fully satisfied the XPC in the NEMA standard.
Furthermore, this product was evaluated as having low odor under heating conditions of 180°C x 30 minutes and 220°C x 30 minutes. Example Six sheets of resin-impregnated paper in the reference example were laminated in the same manner as in the reference example, and at the same time cellophane was used on one side and a commercially available electrolytic copper foil (manufactured by Fukuda Metals, CF) with a thickness of 35 μm was used on the other side.
-T5) was laminated to obtain a single-sided copper-clad laminate with a thickness of 1.6 mm, which was the same as the reference example. This product has soldering heat resistance of 260℃ x 10 seconds.
Peeling strength of copper foil according to JIS C-6481 is 1.0Kg/
cm, and fully satisfied the NEMA standard XPC. Comparative Example In the example, 50Kg/
Attempts were made to cure the resin while applying a pressure of cm ² , but the resin fluid flowed and flowed out so much that production was not possible.

Claims (1)

[Claims] 1. A base material is impregnated with an unsaturated polyester resin liquid that is liquid at room temperature and contains a curing polymerization initiator using a copolymerizable monomer that is liquid at room temperature as a crosslinking agent. After laminating the impregnated base materials and laminating copper foil on at least one side of the laminate, then,
In a method for producing an electrical copper-clad laminate, which comprises curing under substantially no pressure conditions, an aliphatic peroxide is used as the curing polymerization initiator, and the unsaturated polyester is applied to each base material. A method for manufacturing an electrical copper-clad laminate, characterized by impregnating one side with a resin liquid. 2. The method for producing an electrical copper-clad laminate according to claim 1, wherein the aliphatic peroxide as the curing polymerization initiator is an aliphatic peroxyester.