Optimising electronic manufacturing processes

This paper describes a framework for use in electronic manufacturing system optimisation using a systems approach. The framework consists of three phases. Phase 1 is the system-modelling phase where a model of the system to be optimised is created. Phase 2 involves system analysis and control. In this phase, the focus is on identifying manufacturing process areas where analysis and control must be undertaken. A collection of techniques can be used systematically to generate such information and provide an understanding of individual process capability. These techniques include process capability indices, measurement operation evaluation indices and process failure mode and effect critical analysis. The final phase is used to optimise the system using techniques such as experimental design and response surface models. This paper describes the proposed framework and examines its use within the three main areas of electronic manufacturing: PCB manufacture, Si device manufacture and electronic assembly. The framework has been validated within semiconductor, assembly and PCB manufacturing plants. Within the semiconductor facility, one of the stages of the framework investigated was the process capability ratio (PCR), stage IV of the framework. PCR techniques were used to explain the relationship between the technical specification and the production capabilities. Various PCR indices were used such as C_p, C_pk and C_pm and these were generated for various GTO thyristor operations. Use of the C_pk index is illustrated as a means of determining whether the process for gallium resistivity is capable