I have encounted an interesting problem during an experiment intended to compare 95Pb/5Sn with eutectic bumping for a 20x25mm die: Situation 1: 95Pb/5Sn solder bumping, UBM is Ni(2.5um)/Cu(0.2um)/Ti(0.2um) Ti and Cu layer were sputtered. Ni was plated. Situation 2: 63Sn/37Pb bumping, UBM is Ni(2.5um)/Ni(0.2um)/Ti(0.2um) Ti and Ni were sputtered. The outlayer of Ni was plated. Both wafers went through almost the same thermal process during bumping. High lead bumping had one more 360 C de-oxidation process. Then cutter peel test was done on both wafers. Interesting results came up: For situtaion 1, most of bumps were sheared off through intermetallics, leaving mostly Ni surface For situtaion 2, all bumps were sheared off with surface covered by solder. Could anyone give me an explanation, especially from metallury and intermetallic point of view? Thanks, Yuan Li Research Associate --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------