International Business Machines Corporation

David P Daniel

Harry David Cox

Adolf E Wirsing

Leonard J Gardecki

Doris P Pulaski

Ruth A Machell Julianelle

David L Smith

David J Specht

Charles H Keeler

Albert J Gregoritsch, Iii

Mary A Schaffer

A shadow mask for depositing solder bumps includes additional dummy holes located adjacent holes corresponding to most of the perimeter chips of the wafer. The additional dummy provide more uniform plasma etching of contacts of the wafer, improve etching of contacts of perimeter chips, and lower contact resistance of contacts of perimeter chips. The extra holes also provide solder bumps outside the perimeter chips that can be used to support a second shadow mask for deposition of an additional material, such as tin, on the reflowed solder bumps for mounting the chips on a plastic substrate at low temperature. An improved mask to wafer alignment aid is formed from standard solder bumps. The improved alignment aid avoids damage to test probes and provides improved course alignment.

Wafer integrated rigid support ring

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Burlington, VT, United States of America

David P Daniel