This paper deals with the mechanical reliability of controlled collapse solder joints in modules subjected to the thermal fatigue conditions of machine usage. Particular emphasis is placed on design variability and how the shape and dimensions of the joint and chip affect reliability. A systematic technique is presented to optimize pad dimensions. A new experimental method to characterize chip-to-substrate interconnections-the torque test-is described and analyzed. Its applicability to design evaluation is discussed and representative data are analyzed. The relationship between torque test measurements and fatigue is discussed.

No abstract

In 2001, IBM delivered to the marketplace a high-performance UNIX ® -class eServer based on a four-chip multichip module (MCM) code named Regatta. This MCM supports four POWER4 chips, each with 170 million transistors, which utilize the IBM advanced copper back-end interconnect technology. Each chip is attached to the MCM through 7018 flip-chip solder connections. The MCM, fabricated using the IBM high-performance glass-ceramic technology, features 1.7 million internal copper vias and high-density topsurface contact pad arrays with 100-m pads on 200-m centers. Interconnections between chips on the MCM and interconnections to the board for power distribution and MCM-to-MCM communication are provided by 190 meters of co-sintered copper wiring. Additionally, the 5100 off-module connections on the bottom side of the MCM are fabricated at a 1-mm pitch and connected to the board through the use of a novel land grid array technology, thus enabling a compact 85-mm ؋ 85-mm module footprint that enables 8-to 32-way systems with processors operating at 1.1 GHz or 1.3 GHz. The MCM also incorporates advanced thermal solutions that enable 156 W of cooling per chip. This paper presents a detailed overview of the fabrication, assembly, testing, and reliability qualification of this advanced MCM technology.

While it is widely known that flux is needed to maintain an oxide-free surface during soldering, the fact that flux also reduces the surface tension between solder and ambient is neither widely recognized nor treated extensively in the literature. An apparatus is described which quantitatively evaluates the reduction of surface tension in the presence of flux. Representative data of eutectic lead–tin with water white rosin fluxes are presented.

No abstract