Cratering in 90:10 Pb:Sn cast columns in cast column grid array (CCGA) packages caused by column shearing

摘要

Void-like features have been observed on sheared surfaces on 90:10 Pb: Sn columns in ceramic castcolumn grid array (CCGA) packages. On 20 mil diameter columns, these features are typically 3-5 mils across. These features are not voids, they are crater-like fractures caused by the shearing tool.Shearing with a heavy tool causes extensive cratering. Shearing with a razor blade produces few, ifany, of these features. These craters are a concern since they can be mistaken for voids whichaffect the reliability of CCGA devices.