| 摘要 |
<p>PURPOSE:To obtain circuit boards having an extremely excellent heat resistance without curls or creases, moreover, excellent adhesion and strength by applying a specific polyamic acid thereon and curing them up to a semi-cured state, following this, fastening them in use of a metallic plates and then curing them perfectly. CONSTITUTION:On a metallic foil, varnish comprising a polyamic acid mixture is cast which is obtained such that a polyamic acid solution A obtained by reacting 3,3',4,4'-biphenyltetracarboxylic acid dianhydride and paraphenylenediamine, and polyamic acid solution B obtained by reacting pyromellitic dianhydride and 4,4'-diaminodiphenyl ether are blended at the rate of A/B=55/45-75/25, and made a semi-cured state at the temperature of 80 deg.C or higher and 250 deg.C or lower. Next, substances in the semi-cured state are superimposed one another and held by metallic plates 2 wherein the metallic plates is heated by the temperature of 300 deg.C or higher and 450 deg.C or lower in the form of being fastened by metallic bolts in order to cure them perfectly. As heat resisting resin used herein, polyimide is the most suitable which has an excellent adhesiveness to a metallic foil.</p> |
