Investigators: James A. Warren, Carol A. Handwerker, W. Craig Carter, Daniel Josell, and Andrew Roosen

Technical Description:

NIST scientists are working with scientists and engineers from industry and academia to develop an integrated design system for solder interconnects. Collaborating with NIST are: AT&T, AMP, Inc., Digital Equipment Corporation, Edison Welding Institute, Ford Motor Company, General Motors/Delco, Rockwell International Science Center, Marquette University, University of Colorado - Boulder, State University of New York - Binghamton, Susquehanna University, University of Greenwich, University of Technology - Loughborough, University of Wisconsin-Madison, Lehigh University and Sandia National Laboratories. Research is focussed on developing algorithms for modeling solder spreading in specific solder joint geometries and on using the resulting joint shapes as input to models of solder assembly processes and mechanical reliability.

Technical Objectives:

• Develop modeling tools for predicting the geometries of small-scale solder joints with a wide range of starting configurations of interest to industry.

• Develop computational methods for providing solder geometries to other models of processing and reliability.

• Establish an industry-academia-national laboratory working group on solder joint design for the exchange of information and collaboration on topics of special importance.

• Provide a forum for discussion of the calculations and models and access to software through the Internet/WWW.

• Organize workshops and symposia for the working group and others in the electronic packaging community to promote collaboration and bring the community toward a consensus on the features required for a useful solder modeling system.

Anticipated Outcome:

• The design system will be able to evaluate an interconnect design for its susceptibility to defect formation during soldering and for its reliability under conditions of thermo- mechanical fatigue.

• Integrated solder joint design tools will allow packaging designers greater flexibility in the engineering of the next generation of interconnections with higher interconnect densities.

Accomplishments for FY 1995:

• NIST-sponsored workshop with representatives from industry, academia, and national laboratories identified the needs for modeling specific solder joint geometries and established the Solder Interconnect Engineering working group.

• Developed model for wetting balance test geometries and provided quantitative shape predictions for comparison with observed shapes.

• Developed model for predicting the susceptibility of adjacent pads to solder joint bridging.

• Prepared review of the use of the Surface Evolver program for calculation of solder joint shapes. This manuscript will be part of a Working Group-organized issue of the ASME Electronic Packaging journal.

• Established Internet/WWW site for information exchange and the format for providing models to the public.

• Complete shape calculations for a wide range of gull-wing device geometries and provide the information via WWW.

• Hold two additional working group meetings to promote collaboration and to increase the amount of information on the Web site exchange.

• Collaborate with AT&T, Lehigh University, and other group members in comparing model predictions with experimentally determined geometries.

Impacts and Technical Highlights:

• Scientists and engineers from industry, government, and academia established a collaborative program for the development of software modeling tools for improving solder interconnect geometries with the goals of higher manufacturing yields and higher reliability.

• The critical need for such modeling tools was identified by the Semiconductor Industries Association in its 1992 SIA Technology Roadmap for advanced packaging systems.

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Last modified: Mon Jan 06 09:46:15 1997 Metallurgy Webmeister