Research On The Failure And The Law Of Perfor-Mance Variation During Storage Of Semiconduc-Tor Bridge Initiators

Semiconductor bridge (SCB) initiators will experience long-term storage before us-ing,this may affect its reliability and safety.The factors of accelerated life testing were ana-lysed in this paper and an appropriate accelerated life testing were designed for SCB initia-tors.With initiators failure analysis mehods as a guide,the performance variation in accele-rated life testing process and the major failure mode and failure mechanisms of SCB initiators were obtained.The main conclusions are as follows:(1)SCB initiators have two main failure modes:pitting corrosion of Kovar leg wire plat-ing and delay of ignition time;(2)Plating defects and chloride are closely related with leg wire pitting corrosion,in which chloride play a key role.The failure mechanism of pitting corrosion is:plated surface adsorbed a water film in the humidity with impurity ions dissolved in it to form electrolyte solution;and because of the destruction of the surface passivation film by chloride,pitting nucleus are formed in the plating defects,and then pitiing nucleus autocatalyticly develope to corrosion pits.But slightly pitting corrosion does not impact on resistance of SCB initiators.(3)The SCB initiators after storage can be ignited under prescribed condition.And the re-sistance, exploding time and exploding energy of SCB initiators before and after storage have no significant difference, which indicates SCB chips have a good performance under storage.However, there is a delay of ignition time, which is mainly due to the properties change of the charge.The failure mechanism is as follows:For LTNR,its activation energy increases with the increasing of storage time, so that LTNR is more difficultly to reaction under the same excitation condition and results in the delay of ignition time;for the lead thi-ocyanate/potassium chlorate ignition power,its component slowly reaction under storage conditions to make the delay of ignition time;(4)SCB initiators that after storage cannot be ignited at GJB electrostatic discharge con-dition (25kV,500pF,5000Q).Storage does not degrade ESD safety performance of SCB in-itiators.