CBGA、CCGA植球植柱焊接返工可靠性研究

Research on Reliability of Ball/Column Re-Attachment of CBGA/CCGA ICs

多功能、高性能、高可靠及小型化、轻量化是集成电路发展的趋势。以航空航天为代表的高可靠应用中,CBGA和CCGA形式的封装需求在快速增长。CLGA外壳/基板植球或植柱及二次组装之后的使用过程中,常出现焊接不良或其他损伤而导致电路失效,因此需要进行植球植柱焊接返工。在返工过程中,除对焊接外观、焊接层孔隙等进行控制,研究返工过程对植球植柱焊盘镀层的影响也是保证焊接可靠性的重要工作。一次返工后焊盘表面镀金层已不存在,镀镍层也存在被熔蚀等问题,这都对返工工艺及返工后的电路可靠性提出了挑战。文章主要研究返工中镀镍层熔蚀变化趋势以及随返工次数增加焊球/焊柱拉脱强度和剪切强度的变化趋势,并分析返工后电路植球植柱的可靠性。

Multifunction,small size and weight,high performance and reliability are the development trends for intergrated circuit（IC）.In recent years,the application fields（avigation and spaceflight,for example） which require ICs of high reliability,is demanding more and more ICs with CBGA and CCGA package forms.In the process of attaching balls or columns to CLGA shell/substrate and the process of second-assembly of CBGA/CCGA to PCBs,poor soldering is generally induced which possibly cause a failure in use.Rework of balls/columns attachment is therefor necessary.In the process of rework,it is important to research the plated layers of pads as well as soldering appearance,voids of soldering interface etc.After rework of balls/columns attachment,Au-plated layer is of inexistence and Ni-plated layer is partially melted.Both of the problems challenge the rework process and reliability of ICs.The paper is mainly on 3 issues： evolvement trend of Niplated layer,evolvement trends of tensile and shear strength of solder balls and columns,analysis of ICs’ reliability after rework.