Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1641785 | Materials Letters | 2016 | 4 Pages |
Abstract
In three-dimensional (3D) packaging and assembly technology, Lead-free SnAgCu solder joints inevitably experience multiple reflows. The interfacial compounds of Sn3.0Ag0.5Cu (SAC305)/ Electroless Ni-P/Immersion Au (ENIG) solder bump after laser soldering and subsequent hot air reflows were observed by transmission electron microscopy (TEM), respectively. The initial laser soldering played a key role in interfacial compound evolution during the subsequent multiple reflows. After laser soldering, a thin P-rich layer and an ultrafine scallop-type (Ni, Cu)3Sn4 layer formed at the interface of SAC305/ENIG. The valleys of ultrafine (Ni, Cu)3Sn4 grains served as rapid channels for Ni diffusion, which contributed to the formation of dendritic η-(Cu, Ni)6Sn5+(Ni, Cu)3Sn2 intermetallic compounds after the first hot air reflow. However, with the number of reflow times increasing, the η-(Cu, Ni)6Sn5 totally transformed to noodle-like (Ni, Cu)3Sn2 owing to their similarly hexagonal lattice structure and the limited Cu supply in solder.
Related Topics
Physical Sciences and Engineering
Materials Science
Nanotechnology
Authors
Baolei Liu, Yanhong Tian, Wei Liu, Weiwei Wu, Chunqing Wang,