Solderability test requirements for plastic surface mount packages

The development of a filar eyepiece has increased the accuracy and repeatability of measurement of percent coverage after solderability testing. Using this refined dip-and-look or percent-coverage-after-dip method, the differences in hot solder coat and lead-tin solder plate solderability were evaluated. The plated coatings were shown to have better than 10% thickness uniformity across the lead surface. This is reflected in improved solderability after aging. With Sn/Pb plating, 90% coverage can be assured, as compared with the 80% coverage acceptance level for hot solder dip