Advances in wafer underfill processing

摘要

At ECTC 2012, Toray presented results of their study on suppressing wafer level underfill (WUF) material entrapment at copper pillar/pad joints. The NCF (non-conductive film) was laminated on the wafer and then the surface was planarized by the bit cutting technique. Chips were then bonded to Cu/Ni/ Au pads. When the top chip and lower chip are joined, the temp must be raised slightly (sticking process) to get the NCF to flow together. This holds the two chips in place.