Use of organic solderability preservatives on solderability retention of copper after accelerated aging.

摘要

Organic solderability preservatives (OSP's) have been used by the electronics industry for some time to maintain the solderability of circuit boards and components. Since solderability affects both manufacturing efficiency and product reliability, there is significant interest in maintaining good solder wettability. There is often a considerable time interval between the initial fabrication of a circuit board or component and its use at the assembly level. Parts are often stored under a variety of conditions, in many cases not well controlled. Solder wettability can deteriorate during storage, especially in harsh environments. This paper describes the ongoing efforts at Sandia National Laboratories to quantify solder watability on bare and aged copper surfaces. Benzotriazole and imidazole were applied to electronic grade copper to retard aging effects on solderability. The coupons were introduced into Sandia's Facility for Atmospheric Corrosion Testing (FACT) to simulate aging in a typical indoor industrial environment. H(sub 2)S, NO(sub 2) and Cl(sub 2) mixed gas was introduced into the test cell and maintained at 35(degrees)C and 70% relative humidity for test periods of one day to two weeks. The OSP's generally performed better than bare Cu, although solderability diminished with increasing exposure times.