某电路模块厚膜电阻硫化故障分析及预防措施

Fault Analysis and Preventive Measures of A Cricuit Module Thick Film Resistance Vulcanization

通过某电子产品自检异常问题的排故处理,研究了片式厚膜电阻被硅橡胶覆盖后硫化失效问题,发现电阻硫化的主要原因是端电极被硅橡胶覆盖,硅橡胶的多孔结构易吸附周围环境中的硫元素,高浓度的硫化气体通过端电极金属镀层与包覆层间的缝隙进入电阻内部,与银电极发生硫化腐蚀,导致产品故障。针对该问题,提出了改进工艺使硅橡胶避开电阻端电极,以及选用防硫化电阻、涂覆更抗硫化的三防漆和灌封胶等预防措施,以有效提高该类电子产品的抗硫化能力。

The vulcanization failure of a thick film resistor covered by silicone rubber was studied by troubleshooting the abnormal self-test of a military product.It is found that the main reason for the resistance vulcanization is that the end electrode is covered by silicone rubber,and the porous structure of silicone rubber is easy to absorb sulfur elements in the surrounding environment.The high concentration of vulcanized gas enters the resistance through the gap between the metal coating and the coating layer of the end electrode,and vulcanization corrosion occurs with the silver electrode,leading to a product failure.The anti-vulcanization ability of this kind of electronic products can be effectively promoted by improving the technology to make the silicone rubber avoid resistance electrode,selecting anti-vulcanization resistance,coating anti-vulcanization paint and potting glue.