JPH052000B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method for producing a printed circuit board obtained by closely adhering a woven body impregnated with a resin to a conductor and treating the woven body with ionizing radiation. (Conventional technology and its problems) Diaryl phthalate resin has traditionally been widely used in electronic products such as printed circuit boards, insulating parts, decorative boards, and paints due to its excellent heat resistance, electrical insulation, and dimensional stability. It is used. However, most of these materials are used as a laminate of diallyl phthalate resin with phenol paper, nonwoven fabric, glass fiber, etc., or they are used as a base material as a paint. Among these, the most important thing in manufacturing printed circuit boards is the adhesion to the conductor, such as copper foil. Diaryl phthalate resin has poor adhesion to copper foil, and therefore an adhesive is required between the diallyl phthalate resin composite and the copper foil. (Means for Solving the Problem) The present inventors have conducted various studies on a method for manufacturing a printed circuit board that has sufficient curing strength and has excellent adhesion to a conductor without using an adhesive layer. Diaryl phthalate prepolymer impregnated with one or more radically polymerizable monomers
A composite obtained by impregnating a mixture of 80 parts by weight, 80 to 20 parts by weight of a radically polymerizable monomer, and 0.01 to 10 parts by weight of a curing accelerator is brought into close contact with a conductor, and then treated with ionizing radiation. The inventors discovered that the resin composite produced by the inventors has excellent adhesion to conductors, especially copper foil, and completed the present invention. That is, the woven body is impregnated with at least one kind of radically polymerizable monomer. The radically polymerizable monomer used in this case may be (1) a monofunctional monomer or (2) an appropriate combination of a monofunctional monomer and a polyfunctional monomer. . Monofunctional monomers that have one radically polymerizable group at the end may be used, such as vinyl compounds such as vinyl acetate, styrene, and vinylpyridine, acrylic acid, alkyl acrylates, 2-ethylhexyl acrylate, and 2-hydroxy. Acrylate compounds such as alkyl acrylate, ethoxyethoxyethyl acrylate, tetrahydrofurfuryl acrylate, benzyl acrylate, 2-phenoxyethyl acrylate, methacrylic acid, methyl methacrylate, alkyl methacrylate, 2-ethylhexyl methacrylate,
Examples include methacrylic compounds such as 2-hydroxyalkyl methacrylate, ethoxyethyl methacrylate, tetrahydrofurfuryl methacrylate, allyl methacrylate, and glycidyl methacrylate. As polyfunctional monomers, divinylbenzene,
Neopentyl glycol diacrylate, 1,6
-hexanediol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, polyethylene glycol diacrylate, pentaerythritol triacrylate, trimethylolpropane triacrylate, 1,4-butanediol dimethacrylate,
Ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, diallyl phthalate,
diethylene glycol bisallyl carbonate,
Compounds having two or more radically polymerizable groups such as triallyl cyanurate and triallyl isocyanurate are suitable. The term woven body refers to a fabric made by alternately weaving glass fibers or synthetic resin fibers such as polyester or nylon. Next, the woven material impregnated with at least one kind of radically polymerizable monomer is impregnated with a mixture consisting of a diallylphthalate prepolymer, a radically polymerizable monomer, and a curing accelerator to obtain a composite. The diallyl phthalate prepolymer used in the present invention is obtained by polymerizing one or more of diallyl orthophthalate, diallyl isophthalate, and diallyl terephthalate. The polymerization method may be thermal bulk polymerization in the presence of a peroxide such as benzoyl peroxide or methyl ethyl ketone peroxide, or polymerization may be carried out in the presence of oxygen without using a catalyst. Furthermore, a diallyl phthalate prepolymer to which oxygen is added by heat or ionizing radiation in the presence of oxygen may be used as a radical polymerization initiator for polymerization. Thereafter, the monomer and prepolymer are separated by alcohol extraction or the like. The diallyl phthalate prepolymer used in the present invention has a solution viscosity (50% by weight methyl ethyl ketone, 30°C) of 50 to 130 sps, regardless of the polymerization method.
It is sufficient if the iodine value is 50 to 80, the softening point is 130°C or less, and the residual monomer is 5% by weight or less. Further, copolymers of diallyl phthalate and triallyl isocyanurate, triallyl cyanurate, diethylene glycol bisallyl carbonate, etc. can also be used as the prepolymer of the present invention. Further, as the radically polymerizable monomer, those exemplified above can be used as the radically polymerizable monomer that is first impregnated into the woven material. Further, the radically polymerizable monomer used may be the same as or different from the above-mentioned radically polymerizable monomer. The ratio of diallyl phthalate prepolymer and radically polymerizable monomer is 20
~80 parts by weight, preferably 80 to 20 parts by weight of the radically polymerizable monomer. In addition, the ratio of monofunctional monomer/polyfunctional monomer in the radically polymerizable monomer is 100% by weight.
~50/0~50 is preferable, more preferably 100~
70/0 to 30. Since the diallyl phthalate prepolymer is usually obtained as a solid, it is dissolved in a radically polymerizable monomer to obtain a mixture. When the content of the diallyl phthalate prepolymer increases, the viscosity of the mixture increases, impregnation into the woven body becomes insufficient, and the flexibility of the resulting composite decreases. Furthermore, if the content of the diallyl phthalate prepolymer is small, the viscosity of the mixture decreases, and although the impregnation into the woven body is sufficient and the flexibility is improved, the properties as a diallyl phthalate resin are impaired. Further, curing accelerators include, for example, compounds containing a sulfur atom in the molecule, compounds having a thiol group in the molecule, etc.

[Formula] and benzotriazole compounds can be used alone or in combination of two or more. Among these, benzotriazole is preferably used. The amount used is 0.01 to 10 parts by weight based on the mixture of diallylphthalate prepolymer and radically polymerizable monomer, which is suitable for improving the flexibility of the composite and improving the adhesion to conductors, especially copper foil. The woven fabric subjected to the two-step impregnation treatment is placed on the conductor, and excess liquid is removed using known means such as an applicator or roll coater to obtain a predetermined thickness. In this case, examples of the conductor include metal conductors such as copper, aluminum, zinc, and platinum, but copper metal foil containing copper as a main component is particularly preferably used. Further, the support of the composite is usually used to absorb resin sag. The support in this case may be any support as long as it can be easily released from the composite after the resin is cured, and suitable examples include glass plates, polyester films, Teflon films, release paper, and cellophane paper. A resin composite having a predetermined thickness is brought into close contact with a conductor, and the resin composite is irradiated with ionizing radiation to cure the resin. Ionizing radiation refers to X-rays, α-rays, and β-rays.
- rays, γ-rays, electron beams, and ultraviolet rays, but electron beams and ultraviolet rays are preferable from the viewpoints of equipment availability, ease of operation, safety, etc. However, since treatment with ultraviolet rays requires a photopolymerization initiator, there is a problem with the storage stability of the mixture, and because allyl compounds are difficult to polymerize, electron beams with higher energy than ultraviolet rays are not used in the present invention. suitable. The dose of the electron beam is 10 to 100 Mrad, preferably 10 to 50 Mrad. If the dose is less than 10 Mrad, it will be difficult to cure, and if the dose is more than 100 Mrad, productivity will be poor. The accelerating voltage varies depending on the thickness of the resin composite.
100~ when manufacturing resin composites around 200μm
It is 300KV. The irradiation time varies depending on the dose, accelerating voltage, and current, but is usually 0.1 seconds to several seconds. The printed circuit board of the present invention is achieved by irradiating the resin composite with ionizing radiation and then bringing the resin composite into close contact with the conductor. Examples and comparative examples of the present invention will be described below. Example 1 After impregnating a glass cloth with tetrahydrofurfuryl acrylate, a diallyl orthophthalate prepolymer (with an iodine value of
Methyl ethyl ketone solution viscosity at 60, 30℃
100 cps, standard polystyrene equivalent number average molecular weight 8850) 50 parts by weight Tetrahydrofurfuryl acrylate 50 parts by weight and benzotriazole 1 part by weight were again dipped and impregnated. This resin-impregnated glass cloth was placed on a copper foil with a thickness of 35 μm, and the excess liquid was removed using an applicator so that the thickness including the copper foil was approximately 200 μm, and the resin was irradiated with an electron beam under the conditions shown in Table 1 to harden the resin. The performance evaluation results of the obtained printed circuit board are shown in Table 1.

[Table] Example 2 Glass cloth was impregnated with tetrahydrofurfuryl acrylate, and then diallyl orthophthalate prepolymer (iodine value
Methyl ethyl ketone solution viscosity at 60, 30℃
100 cps, number average molecular weight 8850 as calculated from standard polystyrene) 50 parts by weight, tetrahydrofurfuryl acrylate 50 parts by weight, compound containing a sulfur atom in the molecule

[Formula] 1 part by weight of the mixed solution was again immersed for impregnation. This resin-impregnated glass cloth was adhered to copper foil in the same manner as in Example 1, and the resin was cured by irradiation with an electron beam under the conditions shown in Table 2. The performance evaluation results of the resulting printed circuit board are shown in Table 2.

[Table] Comparative Example 1 Diallyl orthophthalate prepolymer (iodine value 60, methyl ethyl ketone solution viscosity at 30°C
After soaking the glass cloth in a mixed solution of 50 parts by weight (100 cps, number average molecular weight 8850 as calculated from standard polystyrene), 50 parts by weight of tetrahydrofurfuryl acrylate, and 5 parts by weight of trimethylolpropane triacrylate, the resin-impregnated glass cloth was thickened.
The printed circuit board was placed on a 35 μm copper foil, removed with an applicator until the thickness including the copper foil was approximately 200 μm, and irradiated with an electron beam under the conditions shown in Table 3 to cure the resin. The performance evaluation results are shown in Table 3.

【table】

[Table] (Effects) The printed circuit board obtained from the present invention has extremely excellent adhesion between the conductor and the resin composite, so it maintains high peel strength and has excellent solder resistance, and can be used without the use of an adhesive. is not necessary.

Claims (1)

[Claims] 1. The woven body is impregnated with at least one radically polymerizable monomer, and then 20 to 80 parts by weight of diallyl phthalate prepolymer, 80 to 20 parts by weight of radically polymerizable monomer, and 0.01 to 10 parts by weight of a curing accelerator. A method for manufacturing a printed circuit board, comprising: adhering a composite obtained by impregnating a mixture consisting of the following to a conductor, and then treating the composite with ionizing radiation.