窄节距焊料凸点成形及焊盘尺寸对抗剪强度和微观组织的影响  

Influence of pad size on shear strength and microstructure of fine pitch solder bump

作　　者：刘子玉[1] 蔡坚[1,2] 王谦[1] 何熙[1] 张龙[1] 

机构地区：[1]清华大学微电子学研究所,北京100084 [2]清华大学信息科学与技术国家重点实验室(筹),北京100084

出　　处：《焊接学报》2015年第11期49-52,115,共4页Transactions of The China Welding Institution

基　　金：国家科技重大专项项目"三维高密度基板及高性能CPU封装技术研发与产业化"(2011ZX02709)

摘　　要：通过优化模板印刷工艺实现了窄节距无铅焊料凸点成形,并观察了凸点形貌、高度以及评估成形的焊料凸点性能.利用拉力剪切力试验机对凸点进行剪切力测试,研究焊盘尺寸对凸点抗剪强度的影响,同时观察了断口形貌,最后对凸点内部及界面处的金属间化合物(intermetallic compound,IMC)进行了观察.结果表明,小尺寸焊盘的凸点较高、均匀性较好,抗剪强度表现出随焊盘尺寸减小而减小的尺寸效应,并从剪切受力和IMC分析尺寸效应的成因.其中大尺寸焊盘的凸点界面IMC形貌为扇贝状,而小尺寸焊盘的界面IMC为针状,容易导致应力集中而降低抗剪强度.Stencil printing process was optimized to obtain fine pitch flip chip solder bump. In order to evaluate the printing process,bump morphology were observed and bump heights were measured. Furthermore,shear force was tested by Pull-Shear Tester to investigate the effect of pad size on shear strength for the fine pitch solder bumps. Fracture surfaces were inspected and intermetallic compounds( IMC) at the surface and in the bump were separately detected and identified. It was found that bump height with small pad size was larger than that with large pad size as well as bump uniformity. Bump shear strength decreased with reducing pad size,which appeared size effect. This phenomenon was attributed to load condition difference during shear testing and IMC variation. Scallop IMC was observed at the bump interface with large pad size and needle like was found at the interface with small pad size,which possibly led to crack stress and decrease shear strength.

关 键 词：倒装芯片 焊料凸点 抗剪强度 焊盘尺寸 金属间化合物 

分 类 号：TG425.1[金属学及工艺—焊接] TG111.91