The significance of desoldering and resoldering methods in robotic automated rework

Abstract

The rework of printed circuit board assembly (PCBA) has been tacitly accepted as necessary since PCBA manufacturing began. Manual rework is unreliable, time-consuming and expensive, and there is a growing need for automated rework. Further, as future assembly methods such as tape automated bonding and chip on board come into use, the ability of humans to perform the rework function at all is in doubt! Currently, with the increasing use of fine-pitch devices, the need for computer-controlled mechanical rework stations has become more important. While PCBA has, in the main, been successfully automated, the same developments have not been evident in component rework. In this paper, commercial reflow techniques for both through-hole (TH) and surface-mount (SM) component rework are discussed and analysed, with the intention of determining the most appropriate to an experimental robotic assembly cell extended to perform single-sided rework based on a batch size of one. The paper shows the importance of the desoldering and resoldering techniques for a fully automated robotic rework cell, examines various possibilities for developing the cell based on different reflow techniques and proposes the most suitable one. It then describes the configuration of reflow equipment in the cell, and concludes with quality and cost data for the cell based on the chosen reflow techniques.