High-density build-up wiring boards using conventional printed wiring boards process

To keep pace with the downsizing of electronic communication equipment and acceleration of transmission speed, the printed wiring board (PWB) must have finer wiring and thinner plating. While various means have been developed to produce these high density boards, we have also developed a process that enables the production of upper and lower surface conductor interconnections on Build-Up substrates using metallic via-posts. The features of the via-post type boards are as follows: (a) it is possible to make them high density, because of the very small via-post developed; (b) Any type of resin can be used; (c) Stacks are possible; that is, mounting a post directly above another post; (d) wirebonding to a pad is possible by use of the via-post. We developed high density, high quality, lower costing, and easier to enable via-post type Build-Up PWBs for Card PCs using conventional PWB equipment. The following is a report on our investigation and the result of trial PWB evaluations.