Degradation of electroless Ni(P) under-bump metallization in Sn3.5Ag and Sn37Pb solders during high-temperature storage
Rohan, James F.
Ó Mathúna, S. Cian
The interfacial reaction between electroless Ni(P) under-bump metallization (UBM) and solders is studied. A P-rich layer forms in the UBM along the solder side after reflow and thermal aging. Crack formation inside the P-rich layer can sometimes penetrate throughout the entire UBM layer structure. The Ni(P) UBM degradation occurs earlier in the Sn3.5Ag solder than in Sn37Pb because of its higher reflow temperature. Despite the formation of a P-rich layer and cracks inside the UBM, it still keeps its original function within the high-temperature storage period in this study. Explanations for the formation of the P-rich layer and cracks in the UBM are outlined along with explanations for the Ni(P) UBM degradation process.
Electronic packaging , Reliability , Lead free , Electroless Ni(P) , Under-bump metallization (UBM) , Intermetallic compound (IMC)
Chen, W.-M., Mccloskey, P., Byrne, P., Cheasty, P., Duffy, G., Rohan, J. F., Boardman, J., Mulcahy, A. and O’Mathuna, S. C. (2004) 'Degradation of electroless Ni(P) under-bump metallization in Sn3.5Ag and Sn37Pb solders during high-temperature storage', Journal of Electronic Materials, 33(8), pp. 900-907.
© TMS-The Minerals, Metals and Materials Society 2004.This is a post-peer-review, pre-copyedit version of an article published in Journal of Electronic Materials. The final authenticated version is available online at: http://dx.doi.org/10.1007/s11664-004-0218-3