ABSTRACT
Placement techniques were initially developed to minimize the total weighted wire length necessary for complete interconnection. But with the increased demand for high quality and reliable performance over time, techniques to address placement for reliability and producibility also became necessary. The reliability of an electronic assembly is based in part on the failure mechanisms of its individual parts and interconnections. Failure mechanisms can be accelerated by temperature extremes, temperature changes and gradients, thermal-mechanical stresses, vibration, corrosion and electrical stresses. Placement for producibility involves addressing the manufacturing and assembly processes, including testing and rework, by taking into account the equipment used, the process flow and human factors. Placement for reliability requires an understanding of the actual operating conditions, under which the assembly will be used and the physical mechanisms involved in potential failures.
