KINETICS OF OXIDATION OF COPPER ALLOY LEADFRAMES

Delamination of the oxide film from copper alloy leadframes is conside red a serious reliability problem for microelectronics packages. In an effort to identify the factors which may lead to the formation of bri ttle and/or poorly adhering oxides, kinetics of oxidation of leadframe s in air was investigated by measuring the oxide thickness as a functi on of time at temperatures ranging from 200 to 300 degrees C. The oxid ation was found to occur fairly rapidly in this temperature range. The oxide has the appearance of incoherent platelets and it consists of C uO and Cu2O. Analysis of the oxidation data indicates a logarithmic gr owth law in the 100-1400nm thickness range,;and an activation energy o f about 19kJ/mol, which is much smaller than that reported for the oxi dation of unalloyed copper by a diffusion mechanism. The results of th is investigation are presented here, indicating the important role of defects in the oxidation of leadframes. (C) 1998 Elsevier Science Ltd. All rights reserved.