| 摘要 |
<p>A process for producing a thermosetting resin varnish with which there can be produced a printed wiring board that has favorable dielectric properties in high-frequency band, realizing significant reduction of transmission loss and that excels in moisture absorption thermostability and thermal expansion performance, being satisfactory in metal foil peel strength. There is disclosed a process for producing a thermosetting resin varnish containing a thermosetting resin composition in which an uncured semi-IPN composite, an inorganic filler and a saturated thermoplastic elastomer are contained. The process is characterized by including the steps of (i) carrying out a preliminary reaction in the presence of polyphenylene ether (A) between a butadiene polymer (B) containing in its molecule 40% or more of 1,2-butadiene units having 1,2-vinyl in the side chains thereof, the butadiene polymer not chemically modified, and a crosslinking agent (C) to thereby obtain a polyphenylene-ether-modified butadiene prepolymer as an uncured semi-IPN composite; (ii) mixing an inorganic filler (D) and a saturated thermoplastic elastomer (E) together to thereby obtain a mixture; and (iii) mixing the obtained mixture with the polyphenylene-ether-modified butadiene prepolymer. Further, there are disclosed, provided using the same, a resin varnish, prepreg and metal-clad laminate.</p> |
