铜银系导电复合材料腐蚀失效研究

采用无氰化学镀工艺，研制出一种导电性良好的镀银铜粉，粉末体积电阻率小于2×10-4Ω·cm，用该粉末为填料制成的导电胶，导电率高（导电填料与树脂的重量比为75：25时，体积电阻率为5×10-4Ω·cm）、抗迁移能力强（比银粉导电胶提高近百倍）、导电稳定（经60℃ 相对湿度100%湿热试验1000h，体积电阻率升高小于20%）.采用粉末微电极技术研究了导电胶抗迁移的机理，结果表明电偶效应是该导电胶具有抗迁移作用的主要原因，铜作为阳极抑制作为阴极的银的溶解，从而降低银形成枝晶的几率.

CORROSION FAILURE OF COMPLEX ELECTRICAL CONDUCTIVE MATIERALS FILLED WITH COPPER AND SILVER POWDERS

One new kind of silver-plated copper powder with high conductivity (volume resistivity of the powder is less than 2×10－4Ω·cm) was developed by the electroless plating without cyanide.The ECAs filled with this silver-plated copper powder exhibit high conductivity ( the volume resistivity of ECAs is less than 5×10－4Ω·cm when the mixing proportion of the resin to powder is 25:75 by weight) ,high migration-resistance (the shortcut time is 100 time longer than silver-filled ECAs in the migration test ) and high electric conductive stability (the volume esistivity increase is not more than 20% after 1000 hours humid-heat test in the condition of 60℃and RH100%).The mechanism of anti-migration was studied using powder microelectrode technique and other electrochemical methods.The results show galvanic coupling effect plays an important role in the anti-migration.Copper as anode restrains cathodic silver dissolved during dissolution then decreases the probability of dendritic growth.