200℃等温时效下SAC305/Co-5%P焊点的界面组织及断裂模式演变

Interfacial Microstructure and Fracture Pattern of SAC305/Co-5%P Solder Joint during Isothermal Aging at 200 ℃

目的研究BGA封装的SAC305/Co-5%P焊点在200℃等温时效下的界面反应。方法制备SAC305/Co-5%P的BGA焊点,200℃等温时效0, 200, 400, 600, 1000 h,采用场发射扫描电镜(配EDS)观察不同时效时间下SAC305/Co-5%P焊点界面的IMC形貌与断口特征,采用焊点接合强度测试仪测试相应的剪切强度变化。结果时效1000 h时,在钎料/Co Sn3的IMC层界面处生成(Cu, Co)_6Sn_5,界面CoSn3的IMC之间的通道得到填充,界面形貌变得平整。随着时效时间的增加,焊点的剪切强度先增后降,位于Sn层断口的断裂模式由韧性断裂向韧脆混合型断裂转变。结论随着时效时间的增加,界面IMC层厚度不断增加,界面IMC形貌发生改变。

The paper aims to research the interfacial reaction of SAC305/Co-5%P solder joints that encapsulated by BGA during isothermal aging at 200 ℃. SAC305/Co-5%P BGA solder joints were prepared by isothermal aging for 0, 200, 400, 600, 1000 h at 200 ℃. The interface IMC morphology and fracture characteristics of SAC305/Co-5%P solder joints were observed by SEM (equip EDS), and the shear strength changes were measured by solder joint strength tester.(Cu, Co)6Sn5 was formed at the interface of solder/CoSn3 IMC layer during isothermal aging for 1000 h;the channel between the interface CoSn3 IMC was filled;and the interface morphology became smooth. With the increase of aging time, the shear strength of solder joints increased first and then decreased. The fracture pattern changed from ductile fracture in Sn layer to ductile-brittle mixed fracture. With the increase of aging time, the thickness of IMC layer increases and the morphology of IMC changes.