Patent ID: 7156283
Filing Date: 2007-01-02
Classification: B23K,H05K

Abstract:
1. A method which may be used for producing a soldered joint between metal balls, wherein the metal balls form part of a ball grid array (BGA) or a chip-scale package (CSP), and between receiving pads for a circuit printed on a substrate or receiving pads on an integrated circuit contained on the chip-scale package, said method comprising: a) depositing a solder cream or an adhesive flux on receiving pad, wherein said receiving pads comprise at least one member selected from the group consisting of: b) placing metal balls onto said receiving pad to form an assembly; c) heating said metal balls above their melting point by placing said assembly into a reflow soldering oven, wherein the total residence time said balls remain in the liquid state is between about 20 sec to about 65 sec; and d) cooling said metal balls; wherein said cooling comprises subjecting said metal balls to a cooling rate of at least about 5° C./sec.