BOARD LEVEL RELIABILITY OF QFP AND QFN TYPE PACKAGES WITH MATTE SN LEAD FINISH

摘要

Matte Sn, along with NiPdAu and SnBi, is in consideration to replace SnPb as the lead finish for lead-frame based IC packages for Pb free assemblies. Board level reliability of packages with this finish is an important aspect in selecting any lead finish. This paper reports data on the solder joint reliability of leaded (TQFP, TSOP) and leadless (MLF) packages with matte Sn finish. Comparisons with SnPb and SnBi finish packages are also provided. The test matrix includes the following: 3 package types (14×14mm TQFP, 12×20mm TSOP, and 7×7mm MLF). 3 lead finishes (Matte Sn, SnPb, and SnBi). 2 leadframe materials (Alloy 42 and copper), and. 3 solder pastes (SnPb and 2 versions of SnAgCu) for board assembly. The board assemblies were tested using lead pull, temperature cycling, and drop conditions. The data shows the packages with Matte Sn finish perform as good or better than packages with SnPb finish during board level testing.