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针对塑封电子器件在湿热环境下的贮存可靠性问题,通过湿热实验考察了湿热环境中的湿度因素对某型塑封器件贮存过程中的吸湿行为、封装表面状态以及电性能的影响.结果表明:环境湿度对塑封器件吸湿过程有显著影响,在同样的温度下相对湿度越高,器件的吸水速率越大,达到饱和时的饱和水汽含量也越大,而湿度对器件水汽吸收达到饱和时间的影响比较小,一般贮存300 h后水汽含量都达到饱和;塑封器件在湿热环境下贮存的主要失效模式是外引线腐蚀,且随着相对湿度增加腐蚀程度更加严重,分析认为器件封装过程中在外引线表面造成的断口、裂纹和针孔等缺陷处是腐蚀发生的敏感区;在贮存期内湿度对塑封器件的电性能影响不大.
Aiming at the problem of storage reliability of plastic electronic devices in hot and humid environment, the effect of moisture in hot and humid environment on the moisture absorption behavior, package surface state and electrical properties of a plastic device during storage was investigated by means of a wet heat test. Humidity has a significant effect on the moisture absorption process of plastic encapsulated devices. The higher the relative humidity at the same temperature, the greater the water absorption rate of the device, the greater the saturated water vapor content when it reaches saturation, while the humidity affects the device moisture saturation time Small, generally 300 h after storage of water vapor content is saturated; plastic device in the hot and humid environment is the main failure mode is the outer lead corrosion, and as the relative humidity increases the degree of corrosion more serious, the analysis that the surface of the device leads in the lead package Of the cracks, cracks and pinholes and other defects at the corrosion area is sensitive to corrosion; during storage humidity has little effect on the electrical properties of plastic parts.