In this paper, a genetic algorithm based method is proposed to solve the problem of minimizing the PCB assembly time for multi-head surface mounting machines. By grouping the reels and by clustering the components the multi-head problem is transformed into a single_head one and then the single-head method is simply applied to the multi-head case. To implement the genetic algorithm, a partial link concept is proposed for genetic operations. Computer simulation results show that the proposed algorithm is superior to the heuristic algorithm that is currently used in industry.