Circuit board assembly torsion tester and method

Abstract

A torsion tester for circuit board assemblies (boards) clamps opposite edges of the board and cyclicly twists the board to provide substantially pure sheer stress in interconnection joints to SMT components for replicating failure modes due to thermal cycling. The boards are automatically centered in the clamps, the distance between the clamps is automatically measured, and the machine rotates one of the clamps to produce out-of-plane deflection which repeat within 0.01 degree per inch of the distance to provide repeatable results. During testing the maximum deflection and torque of each cycle and the location and cycle count at each failure is automatically recorded until a large population of failures is obtained. The population of failures is automatically compared to a statistical database of previous populations to identify any unusual deviations and for determining the reliability of the production process. The system can be used either to monitor the quality of existing board assembly line, to determine the affect or quality of a change in a board assembly process, or to determine the reliability or quality of a new board assembly process.