BGA封装用钨焊球焊点的热可靠性研究  

Thermal reliability of tungsten-ball solder joints for BGA package

作　　者：王文慧 赵兴科 王世泽[1,2] 赵增磊 WANG Wenhui;ZHAO Xingke;WANG Shize;ZHAO Zenglei(Shunde Graduate School,University of Science and Technology Beijing,Foshan528399,Guangdong Province,China;School of Materials Science and Engineering,University of Science and Technology Beijing,Beijing100083,China)

机构地区：[1]北京科技大学顺德研究生院,广东佛山528399 [2]北京科技大学材料科学与工程学院,北京100083

出　　处：《电子元件与材料》2022年第9期974-979,986,共7页Electronic Components And Materials

基　　金：广东省重点领域研发计划激光与增材制造专题(2019B90907002);北京科技大学顺德研究生院科技创新专项资金(BK21BE003)。

摘　　要：球栅阵列(BGA)封装结构组成材料之间线膨胀系数(CTE)的差异,容易造成使用过程中焊点内部热应力产生和累积,成为焊点失效的主要原因之一。针对CTE差异的问题,选用与芯片CTE相近的钨制造BGA焊球,并通过在钨球表面电镀铜改善其钎料润湿性。使用SAC305焊膏制备了钨焊球与铜基板的单焊点试样。采用焊点剪切试验研究了170℃下热老化时间对钨焊球焊点热可靠性的影响。结果表明,焊点剪切强度随老化时长增加而明显下降。与焊态试样相比,经250 h老化处理后,焊点的平均剪切强度由57.9 MPa下降至36.6 MPa。随热老化时间增加,焊点的断裂位置由钎焊金属层转向钨核/铜壳层的界面。经250 h老化处理后,焊点的剪切断裂面出现了铜壳从钨颗粒表面剥落的现象。这意味着加强钨核与铜壳层电镀界面的结合强度有助于提高这种钨焊球焊点的热可靠性。Difference of linear expansion coefficient(CTE)between materials in ball grid array(BGA)packaging structure,a reason to cause generation and accumulation of thermal stress inside a solder joint during the operation of the BGA device,has become one of the leading causes for solder joint failure.To solve the CTE mismatch problem,tungsten balls,with close CTE to silicon chips,were fabricated,and copper layers were electroplated outside to improve their soldering wettability.Single solder joint samples were prepared by soldering a tungsten ball between tow copper substrates using SAC305 solder pastes.The effects of thermal aging time on the thermal reliability of tungsten solder ball solder joints were studied at 170℃by shear test.Results show that the shear strength of the solder joints decreases significantly with longer aging time.Compared with the as-soldered joint,the average shear strength of the solder joint decreases from 57.9 MPa to 36.6 MPa after aged for 250 h.The fracture positions shift from the soldering metal layer to the interface of tungsten/copper-plating layer as the aging time increase.After aged for 250 h,the copper surface layer spalling appears on the fracture surfaces.It implies that strengthening the bonding strength of interface of tungsten/copper plating layer is beneficial to improve the thermal reliability of this type of tungsten ball solder joints.

关 键 词：BGA封装 钨球 电镀铜层 焊点 热可靠性 

分 类 号：TN406[电子电信—微电子学与固体电子学] TG425.1[金属学及工艺—焊接]