Publications

Current approaches to reliability are not adequate to keep pace with the need for faster, better and cheaper products and systems. This is especially true in high consequence of failure applications. The original proposal for the LDRD was to look at this challenge and see if there was a new paradigm that could make reliability predictions, along with a quantitative estimate of the risk in that prediction, in a way that was faster, better and cheaper. Such an approach would be based on the underlying science models that are the backbone of reliability predictions. The new paradigm would be implemented in two software tools: the Virtual Reliability Realization System (VRRS) and the Reliability Expert System (REX). The three-year LDRD was funded at a reduced level for the first year ($120K vs. $250K) and not renewed. Because of the reduced funding, we concentrated on the initial development of the expertise system. We developed an interactive semiconductor calculation tool needed for reliability analyses. We also were able to generate a basic functional system using Microsoft Siteserver Commerce Edition and Microsoft Sequel Server. The base system has the capability to store Office documents from multiple authors, and has the ability to track and charge for usage. The full outline of the knowledge model has been incorporated as well as examples of various types of content.

Artificially enhancing the solder ability of a surface can at times prove to be advantageous. As chip packaging geometries become increasingly complex, the issue of solder wettability becomes significantly more important. Here, the authors examine the effect of varying substrate surface roughness on solder wettability (area of spread) and the time required to reach terminal area of spread. Results are given for solder wetting experiments that were performed on copper (Cu) substrates having chemically etched surfaces, as well as, Alumina (Al{sub 2}O{sub 3}) substrates electroplated with various thicknesses of palladium (Pd). The effect of etching on the Al{sub 2}O{sub 3}/Pd specimens was also examined as related to surface roughness and solder spread. These surface treatments were found to significantly alter wettability. Substantial improvements were observed in both solder wettability and time to wet with the uniformly etched Cu surfaces used in this study. For the Cu substrates, the average terminal area of spread is shown to be directly related to the substrates root mean square (RMS) surface roughness. The rate of wetting of the Cu surfaces is also shown to increase when chemical surface treatment is used. Maximum wetting on the Al{sub 2}O{sub 3}/Pd specimens was found to be directly related to surface smoothness. The average terminal area of spread of Al{sub 2}O{sub 3}/Pd specimens is inversely related to the vertical distance from the highest surface peak to the deepest surface valley (i.e., peak-to-peak variation).