摘要
在PCB制作过程中,由于各层芯板残留内应力的不均匀与热涨系数的不匹配,会有一定的涨缩存在。本文提出了一种非线性涨缩的表征方法,以整个图形的中心为基准,用CAD作出芯板预放后靶标的理论坐标,然后计算理论坐标与实际坐标的偏差,用该偏差绘制过程能力图。结果表明,芯板压合后的非线性差异约为±0.0127 mm,且随机分布,涨缩的非线性差异在一定程度上已经影响到了层间的对位精度。
In the process of PCB manufacturing, the non-uniform internal stress and the unmatched thermal coefficients can induce the expansion and shrinkage of the cores. This paper proposed a characterization method of non-linear expansion-shrinkage. It regarded the pattern center as the origin point of the axes coordinate system, and then calculated the theoretic coordinates with CAD. The difference between actual and theoretic coordinates was the non-liner difference. Then we made a process capability graph about the non-liner difference. Results indicated that the control ability was nearly ＋0.5mil. So we could come to a conclusion that non-linear expansion-shrinkage affect the contraposition accuracy to a certain degree.
出处
《印制电路信息》
2015年第12期29-31,共3页
Printed Circuit Information
关键词
非线性涨缩
表征方法
层间对位
Non-Linear Expansion and Shrinkage
Characterization Method
Contraposition
