Patent ID: 6203690
Filing Date: 2001-03-20
Classification: C25F,H01L

Abstract:
A method of reworking PGA chip carriers having at least one unplated I/O pin, the method comprising the steps of:a. obtaining a PGA chip carrier having at least one I/O pin that is plated with gold over nickel and at least one I/O pin that is unplated but contains a corrosion product where the I/O pin should be plated;b. electrolytically etching the I/O pins with an aqueous etching solution comprising:a metal-providing compound selected from the group consisting of a silver salt, copper salt, copper cyanide, silver cyanide, gold cyanide or mixtures thereof, at a concentration in the range from 1 to 6 g/l as metal;potassium or sodium carbonate at a concentration in the range from 10 to 100 g/l; andpotassium or sodium cyanide at a concentration in the range from 29 to 35 g/l,wherein the etching solution temperature is in the range from 20 to about 30.degree. C., the etching solution pH is in the range from 11.5 to 13, and the current density is in the range from 7.5 to 9.5 mA/cm.sup.2, and wherein the plated I/O pin is stripped of gold and the unplated pin is stripped of corrosion product.