This work investigates the barrier effect of the electroless Ni-Cu-P deposit between Al conductor and Sn-Pb solder bump, as well as the interfacial reaction with the Sn-Pb solder. For the Ni-Cu-P/63Sn-37Pb system, a (Ni, Cu)3Sn4 compound with three different morphologies: fine-grain, whisker, and polygon are formed at the Ni-Cu-P/63Sn-37Pb interface after reflow at 220 °C for 15 s. These (Ni, Cu)3Sn4 crystals transform into polygon shape with smooth appearance during 150 °C aging. For the Ni-Cu-P/95Pb-5Sn system, equiaxial (Ni, Cu)3 Sn4 crystals are formed at the Ni-Cu-P/95Pb-5Sn interface after reflow at 350 °C for 15 s, and they also transform into polygon shape during 150 °C aging. In addition, the Ni-Cu-P deposit will crystallize to form Ni5 P2 during 350 °C reflow. The growth of the (Ni, Cu)3 Sn4 compound by solid state reaction is a diffusion controlled process for both Ni-Cu-P/63Sn-37Pb and Ni-Cu-P/95Pb-5Sn systems. A 4 μm Ni-Cu-P deposit can provide adequate barrier function between an Al conductor and two Sn-Pb solders under 150 °C aging for 1000 h.
|Number of pages||7|
|Journal||IEEE Transactions on Components and Packaging Technologies|
|Publication status||Published - 2001 Dec 1|
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Electrical and Electronic Engineering