John R. Pennacchia

Thin-film multichip module packages for high-end IBM servers

A new generation of multilevel thin-film packages has been developed for IBM high-end S/390® and AS/400® systems. Thin-film structures in these packages are nonplanar and can be fabricated by either pattern electroplating or subtractive etching. Selection criteria for choice of fabrication methods are discussed in terms of electrical performance requirements, ground rules, manufacturability, and cost issues. Two problems encountered in the development phase of the nonplanar thin-film structures were 1) accelerated etching of plated Cu features during Cu seed etching, and 2) corrosion of the bottom-surface metallurgy during etching of Cr at the top surface. Effective solutions were developed on the basis of underlying electrochemical phenomena. Finally, reliability stress procedures used to qualify these packages and results of these procedures are presented.

A family of high performance MCM-C/D packages utilizing cofired alumina multilayer ceramic and a shielded thin film redistribution structure

A family of high performance MCM-C/D packages which are used in the new IBM S390 Enterprise G3 and Multiprise systems is described. The packages are constructed of a shielded thin film redistribution structure on a multilayer cofired alumina/molybdenum pinned substrate. Two sizes are described supporting up to 34 CMOS ASIC chips with high signal counts along with other components. The G3 MCM is hermetically sealed while the MP MCM is nonhermetic. Both packages are qualified for 100 K power on hours and 2500 field on/off cycles.