Advanced Technology Symposium Conference Proceedings


DEVELOPMENT OF A COMPLIANT SOLDER

Authors: John Ranieri and Hsingching Crystal Hsu
Company: Georgia Institute of Tech.
Date Published: 6/11/2002   Conference: Advanced Technology Symposium


Abstract: The microelectronics industry is a rapidly growing field affecting many emerging markets, including the military, communications, computer, automotive, and consumer sectors. The development of the industry is driven by the aim to reduce the size of electronic packages while improving performance and reliability. The miniaturization trend, however, faces the obstacle of accommodating to package/substrate material selection and consistent manufacturability. This obstacle introduces design and manufacturing constraints and quality assurance issues. In particular, solder joints are a major concern in ensuring performance reliability. The increased thermal strain and the accumulation of high triaxial stresses from mechanical fatigue in thermal cycling play a significant role in decreasing solder joint life. Increased chance for acute failure in the solder joint is a challenge that needs resolution to continue reliable performance improvement.

This study develops a new technology to design a compliant solder that can tailor to a solder joint’s desired end-use properties. The compliant interconnect is a solder system formed from any eutectic metal composition (e.g. lead-tin, silver-tin, indiumtin, etc.), and forms an interconnecting network of solder mini-elements with dense pore structures upon solidification. The regular distribution of free surfaces makes the solder system compliant and capable of relieving stresses in thin surface mounts. By adjusting parameters of the compliant solder, i.e., particle size, thickness of metal film on the particle, and type of metals, this technology can be used to custom design for specific applications, materials, and field conditions. This process can be used to engineer both the desired mechanical, morphological and compositional aspects within an interconnection thus tailoring to a solder joint’s desired end-use properties. In addition to customization capabilities of the design, the compliant solder can be manufactured in a just-in-time manner. The degree of compliance can be engineered into each formulation, based on the design requirements for both performance and reliability.

Key words: Compliant solder, porous, eutectic.



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