Additive effect of Kirkendall void formation in Sn-3.5Ag solder joints on common substrates

作者：Gao Feng^*; Nishikawa Hiroshi; Takemoto Tadashi

来源：Journal of Electronic Materials, 2008, 37(1): 45-50.

DOI：10.1007/s11664-007-0234-1

• lead-free solder
• Sn-3.5Ag
• additive
• Kirkendall void
• diffusion
• thermodynamics

The Sn-3.5Ag and Sn-3.5Ag-0.2Co-0.1Ni lead-free solders were investigated on common electronics substrates, namely, organic solderability preservative (OSP) and electroless Ni/immersion Au (ENIG) surface finishes. The formation of Kirkendall voids at the interfacial region during isothermal solid aging was explored. For the Sn-3.5Ag-0.2Co-0.1Ni/OSP solder joint, the Kirkendall voids were present after isothermal solid-state aging at higher temperature (e.g., 150 degrees C); however, the size of voids did not change remarkably with prolonged aging time due to the depressed Cu3Sn layer growth. For ENIG surface finishes, the 0.2Co-0.1Ni additions seemed to enhance the longitudinal groove-shaped voids at the Ni3P layer; however, void formation at the solder/Ni3Sn4 interface was effectively reduced. This might be attributed to the reduced Sn activity in the solder matrix and the suppressed Ni-P-Sn layer formation.

• 出版日期2008-1