Vertical interconnect in multilayer applications using Ormet/sup R/ conductive composites

Abstract

Lamination of circuit layer pairs for multilayer constructions requires an innovative strategy for vertical interconnect in order to achieve high density. Multilayer circuits can be achieved by laminating circuit pairs with the use of an appropriate dielectric bond-ply. Circuit pairs are made of a high performance material with predrilled and plated vias and a pair of copper layers for defining circuitry. Vertical interconnect has been achieved by integrating patterned conductive vias with the bond-ply. The patterning of the bond-ply is achieved using a high speed lasing system. The conductive material interconnection can be made in several ways including patterning directly onto the circuit as well as filling the lased holes in the bond-ply. This presentation will discuss the results of work done using a conductive ink material for vertical interconnect. This organic-metallic (Ormet/sup R/) composite, which is based on transient liquid phase sintering, is used to make a connection between the two pads by alloying with the pad metallization. The partially sintered network also extends through the via interconnect providing a reliable network for electrical conduction. Six layer structures composed of three circuit layer pairs and two via interconnect layers have been manufactured. Good electrical connection has been achieved by connecting 5 mil pads vertically. Cross-sectional examination demonstrates a continuous metal network. Preliminary reliability testing indicates that the connections are electrically and mechanically robust.