ABSTRACT

There is a growing need for a method of evaluating the solderability retention capability of printed circuit parts during inventory storage. These circuit parts, including components, connectors, sockets and printed wiring boards are usually joined together by soldering, hence solderability must be preserved during inventory storage. Without accelerated aging prior to solderability testing, i.e. as with the current common practice, little information is gained concerning the future solderability of such parts.

The IPC formed a Task Group to study Accelerated Aging and recommend a method to be used for simulating long term natural storage. This group surveyed circuit manufacturers to determine what was needed, studied the technical literature on accelerated aging and determined that a suitable method is available for tin and tin/lead alloy coatings - the predominant coating materials. In conducting this study, the task group critically assessed the merits of steam, damp, dry, and steam-oxygen heat aging on the basis of published supporting documentation of test results.

The Accelerated Aging Task Group recommends, for tin and tin/lead alloy coatings, a 20 to 24 hours steam aging of specimens above vigorously boiling distilled water to simulate one year natural clean environment inventory storage. This report documents these findings.