Lead free interconnect materials for the electronics industry

Considerable development and research has been conducted over the last 25 years by many areas of manufacturing to reduce the use of lead and to limit human exposure to lead and products containing lead. Small levels of lead can damage the nervous system of children. Major sources of lead are ingested paint, 75%, and drinking water, 20%. The elimination of lead from all manufacturing products, whether through legislation or through tax incentives, will have a significant impact on the electronic interconnect technologies. In 1993 the National Center for Manufacturing Sciences (NCMS), a not-for-profit cooperative research consortium of more than 215 U.S. North American manufacturers, established multi-year programs. Lead Free Solder Project (LFSP) and Conductive Polymer Interconnect Project (CPIP) involving participants from industry, academia, and national laboratories. The objective of these programs is to identify lead free solder alternative replacement(s) and conductive polymeric materials for lead bearing solders in the electronics industry. The new materials must meet the interconnect performance requirements at operating environments ranging from-55 to +180 degrees centigrade. Numerous lead free alloy solders, each exhibiting unique properties, have been used by electronic manufacturers in specific applications. The major usage of conductive adhesives has been in consumer electronics and children's toys. Before any of these new lead free materials can be applied to the widely diverse electronics industry considerable research and development is required. The NCMS programs involve a study of the material properties, manufacturability, modeling and reliability predictions, economic impact, and toxicological properties.