PROCESS IMPROVEMENT STRATEGIES: IMPLEMENTATION OF A NO-CLEAN PROCESS
Author: Vicente Martinez Mir Company: Manufacturers’ Services Date Published: 8/23/1998
Surface Mount International
Abstract: Constant evaluation of the manufacturing process for ways to improve efficiency and cost-effectiveness is an undeniable reality in the electronics manufacturing services industry. One option is to adopt a no-clean process which can deliver significant improvement in cycle time and costs, by eliminating a process step. No- clean processes also address the unique challenges posed by packages such as BGAs, which are not suitable for cleaning due to the low profile of the device. Also, water sensitive components, like variable resistors or non sealed transformers, can not go through the cleaning process without risking damage to the component. At the same time, no-clean processes support increasing demand for environmentally sound manufacturing. This paper addresses the qualification and successful implementation of a no-clean process for telecommunications and computer products. It discusses the qualification process and process characterization of materials, such as temperature profile and screen print parameters. The paper reviews the impact of no-clean materials on solder joint quality and reliability, and defines strategies for addressing those issues. It also discusses the results of stress test, including humidity, temperature and full test in test vehicles. The paper documents improvement in cycle time and quality, including the reduction of defects in both the reflow solder process and the wave solder process.