Patent DE-102013000057-A1 (DE)
Title: Alloy wire made of material comprising silver-gold alloy, silver-palladium alloy and silver-gold-palladium alloy, useful for wire bonding of components of electronic devices, comprises base wire, and layer of plated metal coating
Inventor: LEE JUN-DER
IPC: C22C5/06
Filed: 2013-01-02
Abstract: Alloy wire (10) made of a material comprising a silver-gold alloy, a silver-palladium alloy and silver-gold-palladium alloy, comprises (a) a base wire produced from material comprising a silver-gold alloy, a silver-palladium alloy and silver-gold-palladium alloy, and (b) at least one layer of a plated metal coating, which covers the base wire, where metal coating is made of material comprising pure gold, pure palladium and a gold-palladium alloy. The base wire exhibiting a polycrystalline structure of a face-centered cubic lattice, comprises >= 20% several grains comprising annealing twins. Alloy wire (10) made of a material comprising a silver-gold alloy, a silver-palladium alloy and silver-gold-palladium alloy, comprises (a) a base wire produced from material comprising a silver-gold alloy, a silver-palladium alloy and silver-gold-palladium alloy, and (b) at least one layer of a plated metal coating, which covers the base wire, where metal coating is made of material comprising pure gold, pure palladium and a gold-palladium alloy. The base wire exhibiting a polycrystalline structure of a face-centered cubic lattice, comprises >= 20% several grains comprising annealing twins, where a central potion of the base wire comprises small grains or equi-axial grains, and other portion of the base wire comprises equi-axial grains. An independent claim is also included for producing the alloy wire, comprising (a) providing a thick wire made of material comprising silver-gold alloy, silver-palladium alloy and silver-gold-palladium alloy, (b) reducing wire diameter of the thick wire to form a thin wire having a wire diameter less than the thick wire in a stepwise manner, using N steps of cold processing molding step, where the shape change is 1-15% compared to an in-process wire from before cold processing molding step, in each (N-1)th and Nth step of cold processing molding step, and N is >= 3, (c) performing N steps of annealing step that are carried out on in-process wire respectively between cold processing molding step and after Nth step of cold processing molding step, where the (N-1)th step of annealing step between the (N-1) th and Nth step of cold processing molding step is performed at an annealing temperature of 0.5-0.7 Tm for annealing period of 1-10 seconds, and Tm is melting point in Kelvin temperature scale of the material of the thick wire, and (d) performing Nth step of annealing step after the Nth step of cold processing molding step at an annealing temperature of 20-100 K higher than that of the (N-1)th step of the annealing step for annealing period of 2-60 seconds, to form thin wire exhibiting polycrystalline structure of face-centered phase and comprising several grains, where a central portion of the thin wire comprises small grains or equi-axial grains, and the other portion of the thin wire comprises equi-axial grains, and forming annealing twins in some of the grains comprising annealing twins.