Scheduling a multi-chip package assembly line with reentrant processes and unrelated parallel machines

A multi-chip package (MCP) consists of several chip modules in a single package. We consider a scheduling problem for assembling MCPs. In order to assemble an MCP, a lot should repeat assembly process stages such as die attach and wire bonding as many as the number of chips to be assembled. The two key process stages have many parallel machines of various types. A machine processes different types of MCP lots with significant setup times. We therefore should limit the number of setups significantly while not sacrificing the on-time delivery performance much. We propose scheduling strategies of appropriately allocating the machine capacity to products and lots depending on the production progress of products and lots. We report experimental performances of the proposed methods.