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Abstract :

The New Alternative Bonding Wire of Ag-Pd Alloy Wire


    Silver-alloy wire has attracted more attention in IC assembly industry recently. And more employment on mass production be reported. Silver-alloy wire showcases the benefit to replace Gold and Copper hybrid wire bonding process. To boost the throughput and cut production time. The wire bonding performance of Silver-alloy wire is similar to Gold Wire. And shows good bonding capability on some particular surface finish material such as Pd-Au or Ni-Ag finger.                                                                             
There are many studies to prove the good performance on Ag-Au-Pd alloy wire, however the High electric resistivity would cause some electricity issue. For this reason and low cost solution, to increase the concentration of Palladium and remove lot of Gold in Silver wire matrix, It’s will obtain the electric resistivity close to 2N Gold wire, The mechanical property such as elongation and breaking load are close to Ag-Au-Pd alloy wire. The wire bonding check item such as FAB outline、1st/2nd bond outline、 wire pull、ball shear、IMC coverage、workability all meet the criteria of products.                                                                       
According to previous studies on L/F and substrate for reliability test, the IMC growth rate of Ag wire is between Cu-Al IMCs, need to be carefully control pH value and Chlorine ion concentration on EMC. The study also report the wire with high Palladium concentration to appeal good reliability on PCT and HAST condition. To confirm the stability of silver alloy wire on the potential migration issue, two strict conditions include Bias – HAST and HTST with current has been employed to verify the workability. There is no O/S issue to be observe after the test and furthermore to verify by the examination of cross section.                                         
Silver wire would be a leading product for next decade.