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

Abstract

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 rigid, plastically deformable solder joint at high speed. Since the conventional probing mechanism has only passive compliance, it cannot effectively control such a large contact force. This uncontrollable excessive contact :force often makes some defects on the surface of the solder joint and oscillatory 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 serially connected macro and micro robotic probing device equipped with active compliance capability and sensing ability of surface conditions of the solder joint in realtime. This paper describes its design characteristics and control scheme of the newly proposed device. The effectiveness of the proposed probing system is verified through a series of experiments. (C) 1999 Elsevier Science Ltd. All rights reserved.