Robotic probing of conformally coated circuit cards

In recent years robotics have been utilized in conjunction with diagnostic probing of circuit cards. Traditionally, manual probing is required to isolate component failures. This requires program interruption, use of reference documents and judgment by the operator. It is expected that the operator will locate the proper test point and place the probe with sufficient force to make contact. Often, errors are introduced because the operator probes the wrong test point or applies insufficient force. These errors result in: replacement of components that have not failed, additional testing, waste of spares and an increase in test time. The incorporation of robotics into the process can eliminate these problems. Using a robotic probe raises questions regarding accuracy of probe placement, its applied force, and potential damage to circuit card traces. The question of insufficient probe force with conformally coated circuit cards is of special concern. A probe that does not make contact results in erroneous conclusions that can cause slowdown and waste. This study focuses on quantifying the force required in conjunction with a robotic probe to make reliable contact. A variety of probe types and various conformal coatings were tested to provide guidelines in their use for robotic testing