Combining process planning and concurrent engineering to support printed circuit board assembly

Abstract

Research in computer integrated manufacturing area has long been concentrated in building the bridges between the islands of design and manufacturing. Many computer-aided process planning systems and design advice systems find success in using Expert System technology to connect design and manufacturing. However, the one-directional inference and hierarchical structure of Expert Systems can only provide a one-way bridge from design to manufacturing or from manufacturing to design. This paper uses interactive constraint modeling to provide a two-way bridge between design and manufacturing and describes PACE II, a process planning and concurrent engineering system for printed circuit boards (PCB). Interactive constraint modeling is a formalism that can represent mutually constraining parameters and their relationships as a set of inter-related constraints. It provides omni-directional and interactive inference to act as a two-way bridge between design and manufacturing in order to solve concurrent engineering problems. By using an interactive constraint modeling environment called Jupiter, the PCB process planning knowledge can be represented in PACE II by a collection of variables which are interlinked by constraints that specify relationships among them. The PACE II system demonstrates that by using interactive constraint modeling, the knowledge involved in process planning can not only generate the process plan but can also serve as a design aid to show the impact of design variations on the manufacturing process. It dynamically generates the process plan from PCB design attributes and detects inconsistencies between the PCB design and the existing production environment, thereby helping to ensure that concurrent engineering can be carried out during the design phase.