灌胶工艺对陶封隔离器键合点影响仿真分析

Simulation analysis of influence of glue-potting workmanship on bonding point of ceramic seal isolator

陶封隔离器由于引线间距过小,需采用灌胶的方法来加强其绝缘性能,使其隔离电压从而满足安全需求。灌封后因去胶困难,键合试验无法进行。针对上述问题,文中以GL3200C型数字隔离器为研究对象,采用有限元仿真方法分析在经历温度循环时,灌封胶对陶瓷封装数字隔离器内部键合点的影响,确定灌胶隔离器键合点易发生失效的薄弱环节,明确其失效机理。通过调研器件手册以及开盖器件的内部结构,以Solidworks软件建立灌胶隔离器仿真模型,并利用有限元仿真软件ANSYS Workbench进行仿真分析。结果表明,灌封胶与基板、外壳之间热匹配不良会使键合丝危险位置额外承受约6.45 GPa的剪切应力。该研究可为无法进行键合点强度可靠性考核试验的灌胶器件分析提供一种新思路。

As the lead spacing of ceramic seal isolator is too short,it is necessary to use glue-potting method to strengthen its insulation performance and make it isolate the voltage,so as to meet the safety requirements. After glue-potting,the bonding test could not be carried out due to the difficulty in removing glue. On this basis,the GL3200C digital isolator is taken as research object,and the finite element simulation method is used to analyze the influence of sealant on the internal bonding point of ceramic-package digital isolator during temperature cycle,determine the weak link that is easy to fail at the bonding point of glue-potting isolator,and make the failure mechanism get known. The Solidworks software is used to establish the simulation model of the glue-potting isolator by researching on the device manual and the internal structure of open-cover device.The finite element simulation software ANSYS Workbench is used for the simulation analysis. The results show that poor thermal matching between sealant,substrate and shell can result in an additional shear stress of about 6.45 GPa on the dangerous position of bonding wire. This study can provide a new idea for the analysis of glue-potting devices,on which the reliability assessment test of bonding point strength cannot be carry out.