Process and Accelerated Aging Test of GANG Bonding for Gold-PlatedTAB Outer Leads

[摘要] This paper presents the evaluation results of thermocompression GANG Bonding of gold-plated TAB outer leads tothree kinds of metallized ceramic substrates. Gold-Selective Plating (GSP) substrates for multi-chip package, ThickFilm (TF) substrates for multi-chip package and Single Chip Packages (SCP) which have a trimetal combination ofrefractory metal (tungsten), Nickel and Gold.The bonding parameters such as the bonding tool (thermode) temperature, pressure, bonding time and preheattemperature were examined on each substrate to get optimum values. As the result, a relation between pull strengthand the lead deformation shows that the TAB leads should be bonded with 15–65 percent deformation, the recommended parameters are; the tool temperature of 380–430℃, the bonding pressure ranging from 35 to45 kg/mm2, with the preheat temperature of 150℃ and the bonding time from 1.0 to 2.5 seconds.The evaluation of initial bondability shows that TAB GANG Bonding has the capability of excellent bondingstrength; above 120 grams with standard deviation of less than 20 grams, and the necessity of OLB pads flatness; lessthan ±12μm for one ounce copper lead. The normal storage of the substrate and the lead does not affect thebondability. And the results of accelerated aging test of 125℃, 150℃ and 175℃ for more than 8,000 hours showthat a lifetime of greater than 70 years at 65℃ operating temperature is predicted. The effective activation energy forthe pull strength degradation is 0.86–1.05 eV. This is in reasonable agreement with predictions for interdiffusion ofCu–Au. And no significant degradation of the electric resistance was observed on the GSP samples.The feasibility and the high reliability of the GANG Bonding for gold-plated TAB outer leads were confirmed.

[学科分类] 工程和技术（综合）