A new macro/micro robotic probing system for the in-circuit test of PCBs

This paper presents a new macro/micro robotic probing system developed for the incircuit test of printed circuit boards (PCBs). Commercially available robotic probing devices are likely to generate excessive contact force due to their uncontrollability, as a rigid probe makes a contact with a less r igid, plastically deformable solder joint at high speed. Since the conventi onal probing mechanism has only passive compliance, it cannot effectively c ontrol such a large contact force. This uncontrollable excessive contact :f orce often makes some defects on the surface of the solder joint and oscill atory motions of the probe, resulting in unreliable test data. In addition, contact with a steep surface of the solder joint makes slip motion of the probe tip onto the surface. To overcome these problems, we propose a serial ly connected macro and micro robotic probing device equipped with active co mpliance capability and sensing ability of surface conditions of the solder joint in realtime. This paper describes its design characteristics and con trol scheme of the newly proposed device. The effectiveness of the proposed probing system is verified through a series of experiments. (C) 1999 Elsev ier Science Ltd. All rights reserved.