Is Present-Day Accelerated Reliability Testing Adequate for Surface Mount Attachment Evaluation?

The MIL-specs, whether required or not, that have been used on SMT assemblies typically involve temperature cycling with the temperature extremes ranging from -65% C to +150 degrees C. These thermal cycling/thermal shock testing regimens are purported to assure the reliability of SMT assemblie, in particular the reliability of the solder joints in the field. Many of the materials involved in SMT assemblies not only undergo drastic property changes in this temperature range, but some of their physical properties vary, in addition to temperature, with time, strain/stress level, strain rate and frequency.