电子硅胶对霍尔芯片性能改善的研究

The Study about Hall Sensor Chip Performance Improved with Additional Silica Gel Layer

封装结构应力失衡导致的霍尔芯片形变会造成霍尔灵敏度温漂和零点输出等性能变差。通过在芯片和塑封体之间增加电子保护硅胶层,可优化形变问题,使相关性能得到改善。首先测得电子硅胶和环氧塑封料的热膨胀系数,利用仿真软件计算得到2组芯片(有电子硅胶组和对照组)霍尔元件所受应力值,然后对制备得到的2组芯片实物进行云纹测试、超声扫描和电性能测试。结果表明,有电子硅胶芯片在实验温度区间翘曲度变化更加收敛,可靠性试验后,声扫没有分层失效问题;灵敏度温漂测试数据表明,有电子硅胶组在各温度点都有更好的收敛性,在45℃时收敛改善最为明显,标准差值从6.40改善至2.32;零点输出数据表明,有电子硅胶组在各温度点数据更接近目标值(2.5mV),其均值与目标差值从1.6E-3提升至1.2E-3。

Structural changed caused by unbalanced package stress,which would lead sensitivity drift and zero output performance deterioration.The issue could be effectively improved by additional electronic silica gel layer between chip and plastic seal layer.Firstly,the CTE value of electronic silica gel and plastic seal had been tested,and the hall sensor’s stress value in different groups(within and without E-Silica gel layer)had been calculated by simulation software.Secondly,two group chips had been prepared,and tested by moire test,C-SACN and electric test.The result show the group with Silica gel had better warping value consistency performance,and both group chip had no structural delamination failure after reliability test.The group with Silica gel layer had better convergence performance in sensitivity temperature drift test in 40℃,optimized from 6.4 to 2.3.The zero output test data of group with Silica gel layer had closer value to the target(2.5 mV),and typical difference value had been optimized form 1.6E-3 to 1.2E-3.