Removal force models for component disassembly from waste printed circuit board

Printed circuit board (PCB) disassembly is one of the most difficult tasks in recycling waste electrical and electronic equipment. Analysis of the disassembly mechanics is needed for development of disassembly methods for PCB. However, a broad technological gap exists between research on PCB disassembly and industrial applications. One reason is that current research is mainly based on qualitative analyses or experiments without in-depth study of the disassembly mechanics. This paper presents four removal force models for through-hole devices (THD) and surface mount devices (SMD) with a graphical analytical method to determine whether an external force is needed, to calculate the acceleration for removing the components, and to define the acceleration range to disassemble PCB's with various components. The minimum removal forces and/or accelerations for four kinds of conditions are calculated. The results show that THDs can be easily disassembled with small forces or accelerations when no pin is clinched. If the pins are clinched, the removal force increases greatly as the bend angle increases. Small removal forces are required for disassembling various SMDs, but the minimal removal accelerations needed for disassembling SMDs vary greatly with the total wetted length. As the total wetted length increases, the minimum removal force increases while the minimum removal acceleration decreases. The results are used to recommend PCB component disassembly methods. This research will assist with component recovery as well as material separation and provides a quantitative analysis of selection of disassembly methods and the development of disassembly equipment for dismantling waste PCB.