Statistical Analysis of Data from the Solderability Testing of Electroless Nickel Plated Kovar Leads

摘要

Many Sandia National Laboratories components require electrical leads to be soldered to an assembly such as a printed wiring board. In late 1982, a supplier reported to Sandia that they had problems soldering leads of a 14/16 pin integrated circuit flatpack to printed wiring boards. These problems led to the investigation described herein of the fluxes used in solder-dipping. This study shows that Alpha 611 flux, used by the supplier, is not active enough to wet an electroless nickel-plated surface that has been exposed to 200C for 16 hours (which is a condition seen in production prior to soldering). Two Blackstone fluxes included in the study did provide uniform wetting in this situation and also for room temperature curing, even though the time in flux ranged from .25 to 10 minutes. Blackstone 642 flux had a higher wetting rate and lower contact angle than Blackstone 2508. However, Flux residues of B-642 contain chloride ions; therefore, B-2508 has now been adopted by the supplier. (ERA citation 11:013976)