A NOVEL TYPE OF LOW DIELECTRIC AND HEAT-RESISTANT RESIN FOR PRINTED WIRING BOARDS

We developed a novel type of low dielectric and heat-resistant resin. The resin was synthesized from dehydrating reaction between fused arom atics and 1,4-benzenedimethanol, therefore, it was called advanced Pol ycondensed Fused Polynuclear Aromatic Resin (advanced COPNA-Resin). Th e advanced COPNA-Resin exhibited characteristic properties for an elec trical insulator: e.g., high TK (250 degrees C), low dielectric consta nt (3.1 for 1 MHz), and low water absorption (0.37 wt.%). We studied f abrication and properties of prepregs, double-sided copper-clad lamina tes, printed wiring boards with copper-plated through-holes using adva nced COPNA-Resin as an insulating material. Prepregs were fabricated b y the dipping process of E-glass or T-glass fiber woven fabrics into t he resin solution. Copper-clad laminates were obtained by hot-press fa brication of advanced COPNA-Resin prepregs. The laminates reinforced b y E-glass fiber woven fabrics exhibited characteristic properties for multilaying printed wiring boards, Tg was 255 degrees C. The dielectri c constant was 4.2. Advanced COPNA-Resin laminates exhibited higher Tg and lower dielectric constant than polyimide laminates known as heat- resistant and low dielectric materials. The linear thermal expansion c oefficient of advanced COPNA-Resin laminates for xy-axis was 4-5 ppm, and that for z-axis was 29 ppm. Advanced COPNA-Resin printed wiring bo ard exhibited outstanding reliability of electrical connection of copp er-plated through-holes in comparison with the epoxy or the polyimide system. From those analysis for Tg, dielectric constant, linear therma l expansion coefficients, and through-hole reliability, the advanced C OPNA-Resin was regarded as novel type of advanced material for high-de nsity interconnects such as fine-pitch surface mount and multichip mod ules.