Alternating reaction phases in Sn-Cu/Ni-Co solid-state reactions

作者：Chen Chih chi^*; Chen Yue ting

来源：Journal of Alloys and Compounds, 2012, 545: 28-31.

DOI：10.1016/j.jallcom.2012.08.052

• ntermetallics
• Solid state reactions
• Diffusion
• Phase diagrams

This study investigates Sn-Cu/Ni-Co solid-state interfacial reactions to evaluate Ni-Co alloys as new diffusion barrier layer materials for flip chip packaging of Cu/low-k chips. Sn-Cu alloys are promising leadfree solders. In Sn-Cu/Ni-20 at%Co interfacial reactions, after 115 h reaction, the reaction phases are CoSn2/Ni3Sn4. After 720 h reaction, the reaction phases are CoSn2/Ni3Sn4/CoSn2/Ni3Sn4. An unusual alternating reaction phase phenomenon, CoSn2/Ni3Sn4/CoSn2/Ni3Sn4/CoSn2/Ni3Sn4/CoSn2/Ni3Sn4, is found after 1006 h reaction. This alternating phenomenon is attributed to the small mobility of Ni in comparison with Sn and Co. In Sn-Cu/Ni-40 at%Co interfacial reactions, only Sn and Co are dominant diffusion species, and their mobilities do not differ significantly. Only CoSn2 and CoSn3 single layers are formed. The alternating phenomenon is not observed.

• 出版日期2012-12-25