Abstract
Advanced vertical interconnect technology that combines traditional HDI structures feature micro-vias and conductive paste-vias was developed to fabricate multilayer PWB, owning excellent electrical performance, mechanical reliability and mass productivity at reasonable cost. This advanced multilayer PWB is constituted of high elastic modulus thermosetting dielectric composition (Glass epoxy (FR-4)) with interstitial via holes and/or Cu micro-vias, and sintered conductive paste-vias buried in low elastic modulus thermosetting dielectric composition. The latter composition properly act as mechanical buffering layer of vertical interconnection between upper and lower multilayer PWB.
The first in this paper, manufacturing process condition was discussed the optimum electrical performance at the interface of HDI Cu lands and conductive paste with interposing low elastic modulus dielectric material was achieved. Next, the micro structure and sintering condition at the interface of conductive paste and HDI Cu land was observed and analyzed by using SEM and EDX. In addition, mechanical reliabilities, estimated by applying structural analysis method, and signal transmission properties by way of this buried conductive paste, analyzed by frequency and time-domain simulation, were discussed. From these results, it was found that this advanced vertical interconnect technology with sintered conductive paste and low elastic dielectric shows sufficient mechanical reliability and electrical property for passing high-speed signal up to 15 Gbps.
