A new probing system for the in-circuit test of a PCB

A new probing mechanism and an active compliance control algorithm have been developed for the in-circuit test of a PCB. Commercially available robotic probing devices are incapable of controlling contact force generated when a rigid probe contacts with a solder joint at high speed. This uncontrollable excessive contact force makes some defects on the surface of the solder joint, which is plastically deformable over some limited contact force. This force also makes unstable contact motions resulting in unreliable test data To overcome these problems, the authors propose that serially connected macro and micro actuators with active compliance provide the best potential for the safe and reliable in-circuit test. Moreover, the depth of penetration on a solder joint can be regulated after contact. This paper describes the design characteristics, modeling, and control scheme about the newly proposed devices. The comparison of conventional passive compliance and force feedback control methods with the proposed control scheme for the contact force control is presented. The experimental results clearly show the effectiveness of the proposed system.