High Density Multilayer Printed Wiring Boards Using UTC as the Surface Layer

Abstract

High density packaging mounted VLSI demand highly dense and highly accurate multilayer printed wiring boards. The authors have studied Ultra Thin Copper (UTC) technology of printed wiring boards for application to the packages of high speed and high performance computers for more than 10 years. This paper describes the requirement for fine line and highly dense multilayer printed wiring boards and the study of the development of a suitable process using the UTC. The discussions include the behaviour of pattern etching and effects of plating thickness, the improvement of plating thickness uniformity, the selection of carrier types, the measurement of peel strength between copper foil and substrate, and so on. The UTC application reduces the defects caused by surface contamination of epoxy resin. Degradation of surface resistance is also discussed, which may be caused by surface creeping of alkaline ions arising from residues of plating solution within the plated‐through hole wall. These investigations could establish UTC technology for fine line printed wiring boards.

Citation

Hanabusa, T., Yamamoto, K., Yamashita, M. and Takagi, K. (1985), "High Density Multilayer Printed Wiring Boards Using UTC as the Surface Layer", Circuit World, Vol. 11 No. 4, pp. 4-9. https://doi.org/10.1108/eb043758