Highly thermal conductive multi-layered printed wiring board

Recently, semiconductor devises are getting more integrated and their performance is becoming higher performance. At the same time, the heat from those devices is increasing and localized. For those devices, highly thermal conductive substrate has been strongly required To meet the requirement above, an epoxy-alumina composite substrate has been developed by a ceramic green sheet process. With that process, the alumina filler contents can be up to 90wt% and the substrate has higher thermal conductivity (3 W/mK). It is much higher than that of conventional printed wiring board (PWB). Using the composite substrate technology, we developed a new multi-layered PWB (ML-PWB), which offers high thermal conductivity and any layer inner via hole structure. This ML-PWB design is based on via hole processing technology using a laser and interconnection technology using conductive paste. This paper presents the results of our study, especially the reliability of the inner via hole interconnection and the co-laminating process using wiring pattern transfer technique for ML-PWB.