MCM-L substrates fabricated using patterned TLPS conductive composites

MCM-L substrates are continually increasing in complexity and density requiring finer dimensions. Two layer requirements can be met by circuit pairs made of a high performance organic material with predrilled and plated vias and a pair of copper layers for defining circuitry. Lines and spaces of less than 50 /spl mu/m with vias of 25 /spl mu/m can be achieved with this material; however, lamination of several of these two-layer circuits to achieve multilayer constructions requires an innovative approach to vertical interconnect in order to achieve the high density required. The one strategy undertaken in this research to use an appropriate dielectric bond-ply and patterned conductive materials. The conductor material is an organic-metallic (Ormet*) composite. The material is based on transient liquid phase sintering (TLPS) and is used to make a connection between the two pads by alloying with the pad metallization. The alloyed metallurgical web formed provides a reliable network for electrical conduction. The results of fabrication and testing of high density multilayer MCM-L substrates using lamination of high performance circuit pairs are presented. Several types of multilayer structures composed of circuit layer pairs and via interconnect layers have been built. Examples of these structures are presented. Good electrical connection has been achieved by vertically interconnecting pads as small as 100 /spl mu/m throughout the structure. Initial reliability testing demonstrates the high integrity of these structures.