Real-time decision support for assembly and test operations in semiconductor manufacturing

This article presents an efficient procedure for prioritizing machine changeovers in a semiconductor assembly and test facility on a periodic basis. In daily planning, target machine–tooling combinations are derived based on work-in-process, due dates, and backlogs. As machines finish their current lots, they need to be reconfigured to match their target setups. The proposed algorithm is designed to achieve this objective and run in real time. It first determines which machines are set up optimally and for those that are not it sequentially calculates how best to reset them within a given amount of time taking into account when the necessary tooling will become available, the importance of the lots in queue, and the given targets. Alternatively, two mixed-integer programming models are also presented that have similar objectives. Experimental results using data provided by a leading semiconductor manufacturer indicate that high-quality solutions can be obtained with the prioritizing procedure in negligible time. In most cases, these solutions are identical to those obtained with one of the two optimization models.