倒装工艺中底部填充胶孔洞的分析与改善

Analysis and Improvement of Underfill Hole in Flip-chip Process

随着倒装封装中焊球间隙的不断缩小,底部填充工艺难度也逐渐地增加。尤其是对于铜柱型焊球倒装产品,其固化后出现孔洞的现象越来越多。如何减少底部填充空洞,降低可靠性失效的风险,是产品工艺工程师、封装设计工程师与材料供应商需要共同解决的问题。阐述了底部填充工艺中出现孔洞的原因,并将其分为随机分布型孔洞、助焊剂残留型孔洞和空气内包型孔洞3类。结合研究文献与实际工程经验,从焊球分布和底部填充工艺方面给出了改善建议,对于底部填充孔洞的解决与改善具有一定的参考意义。

As the gap of the solder balls in the flip-chip package continues to shrink,the difficulty of the underfill process gradually increases.Especially for the copper-pillar type solder ball flip-chip products,there are more and more holes appearing after curing.How to reduce the bottom filling cavity and reduce the risk of reliability failure is a problem that product process engineers,packaging design engineers and material suppliers need to solve together.The reasons for the occurrence of holes in the bottom filling process are described,and these holes are divided into three types:randomly distributed holes,flux residual holes and air wrapped holes.In combination with the research literature and practical engineering experience,the improvement suggestion is given from the aspects of the solder ball distribution and the bottom filling process,which has certain reference significance for the solution and improvement of bottom filling hole.