Study on path-optimization by grade for sorting dies

Semiconductor light-emitting die (LED) has now become one of the most popular lighting devices. Before dies are put into process of package, they need be inspected and sorted strictly, so following waste will be saved. Cost of inspection and sort is relatively high, it is urgently needed to improve sort efficiency and reduce sort time. To get efficient solution, detailed view of working flow is presented to make analysis on performance and its influenced factors. It can be revealed that positioning of recycle bins is the major influence factor. Performance may decrease by 3.2 to 0.9 dies per second. Because of this, a path optimization method according grade priority is put forward. In this way, the dies with same grade should get priority to be sorted first. Techniques about die search and merge by grade, traversal of forward and backtrack with cross priority are described in detail. With results of reasonable simulations and a case experiment, this optimization is proved highly effective to reduce sort time and improve dies production rate.