An actively compliable probing system

A new probing mechanism and an associated active compliance control algorithm have been developed for in-circuit test of a PCB (printed circuit board). 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 often 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, we propose a serially connected macro and micro manipulator equipped with active compliance capability for safe and reliable in-circuit test. Moreover, with this probe the depth of penetration onto a solder joint can be regulated after contact. This article describes the design characteristics, modeling, and control scheme of 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 results obtained from a series of experiments clearly show the effectiveness of the proposed system.