ALLOY FOR IC LEAD HAVING EXCELLENT STRESS CORROSION CRACKING RESISTANCE

• Main Author: SAKAMOTO DAIJI
• Format: Patent
• Language: English
• Published: 25.12.1989
• Subjects: ALLOYS; BASIC ELECTRIC ELEMENTS; CHEMISTRY; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR; ELECTRICITY; FERROUS OR NON-FERROUS ALLOYS; METALLURGY; SEMICONDUCTOR DEVICES; TREATMENT OF ALLOYS OR NON-FERROUS METALS

PURPOSE:To improve the stress corrosion cracking resistance of the subject alloy without deteriorating its solderability, plating characteristics and mechanical strength by limiting the content of Ni, Co, etc., in a kovar alloy and specifying the semi-value width of the X-ray diffraction peak on the prescribed crystal face of the rolled face. CONSTITUTION:An alloy constituted of, by weight, 25-35% Ni, 10-20% Co, <=0.05% C, <=2.0% Mn and the balance substantial Fe is melted, cast and hot- rolled. After that, cold rolling and softening annealing are repeated thereto, and the alloy is subjected to finish rolling at prescribed final cold rolling rate. The alloy is then subjected to appropriate stress-relief annealing to prepare it into an alloy having the semi-value width of the X-ray diffraction peak on the prescribed crystal face (311) of the rolled face in the range of 0.55-0.85 degrees. In the alloy, <=0.005% S and <=0.005% N are furthermore preferably regulated. By this method, the residual strain inherent in the alloy is reduced to improve the stress corrosion cracking resistance of a kovar alloy, by which an IC lead alloy which permits the high reliability of a semiconductor device can be obtd.