Au/In等温凝固焊接失效模式研究

Study of failure modes for die bonding by Au/In isothermal solidification

研究了 Au/In等温凝固芯片焊接的失效模式 ,对每种失效模式的失效原因进行了讨论 ,并提 出了相应的解决途径。结果表明 :镀铟层过厚 ,会使焊层中产生 Ni9In4相和大量空洞 ,导致焊层出现 早期失效 ;焊接过程中芯片与衬底平行度不好 ,会使加载压力在焊区分布不均 ,并导致焊区局部区 域发生 Au/In不浸润 ;焊接温度过高 ,则焊层内会出现较大的热应力 ,可导致芯片或焊层开裂 ;在 300oC高温下 ,由于过渡层 Ni与 Au/In相的反应 ,焊区内出现大量空洞 ,导致焊层剪切强度下降。 对 Au/In体系在未来高温电子器件芯片焊接中的应用 ,尚需寻找合适的过渡层材料。

The failure modes for die bonding by Au/In isothermal solidification technique are documented, the failure causes are discussed and preventive measures are suggested. Excessive indium will cause the formation of Ni9In4 phase and large quantity of voids in the bonding layer which would result in earlier failure. Bad parallelism between the bond head and the substrate will cause non-homogeneous distribution of load in the bonding layer, which is responsible for local non-wetting between gold and indium. If the bonding temperature is too high, the thermal stress in the bonding layer may cause die or bond cracking. At about 300oC, nickel reacts with the Au/In intermetallic phases, which leads to decrement of the die shear strength and the formation of large amount of voids in the bonding layer. So for the die attachment of high temperature devices, suitable barrier layer is needed.