Predicting solder joint reliability, model validation

A reliability predictive technique is presented using a commercially available finite element code and previously developed material properties for eutectic tin-lead solder. The predictive model is validated for three types of surface mount solder joints, i.e., 50 mil gull, 25 mil gull, and 50 mil-butt leaded joints and also a 100 mil intrusive leaded joint using a combination of crack length and “Mechanical Strength Degradation” which is a metric developed at Digital. An accelerated thermal cycle is used to expedite the qualification and validation process. This technique can also be applied to leadless (bump) SMT joints