影响BGA金属件和印制插头顶部宽度的因子浅析

Analysis of factors in the wire-bonding finger width for BGA

在当今电子加工行业,金属线键合还被大量应用于BGA封装。但随着产品集成度提高,对封装载板的线路加工精度越来越高,线路加工工艺已经由传统的减成法(Tenting)加工工艺,逐渐演变为加成法(MSAP、SAP)等。但是占有最大的市场份额的还是减成法。掌握影响成品金属线键合的印制插头顶部宽度的因素,将有助于载板供应商优化工艺参数,增大成品金属线键合的印制插头的顶部宽度,降低金属线键合不良的风险。文章从数学角度,对成品金属线键合的印制插头横截面建立模型,理论计算影响其顶部宽度的因素。利用mini-tab中的因子分析工具,通过研究相关矩阵和协方差阵的内部依赖关系出发,把一些多个变量归结为少数几个深层次因子。结合因子得分,确定影响打金属线键合的印制插头宽度的关键监控需要因子,再通过DOE试验设计不同金属线键合的印制插头,导出可以控制BGA金属线键合的印制插头顶部宽度的黄金法则,并进行实物分析认证。

Nowadays, wire-bonding is still boardly used in the BGA packing. While with the density of the electronic products increase, so does the I/O number, which means the fine pitch requirement of the Substrate becomes more and more urgent. And the traditional process（tenting） is gradually updated to MSAP/SAP etc. However, the tenting process is still holding the most market. Knowing the factors in the wire-bonding finger width will help the substrate vendor optimize .the process parameters, increase the width of fingers and decrease the wire- bonding failure. From the side of mathematics, this article establishes the model for the micro-section of wire- bonding finger, analyzes the factors that maybe affect the top width of them. Utilizing the mini-tab can deal with huge date analysis, and we study the relation of the factors with matrix and covariance. Hence, we can just work out the main factors and mark them synthetically. Eventually, we found how the main factors contribute to the width of Au finger, and make the golden formulae for the finger width, then utilize this disciplinarian to optimize manufacture process.