Udo Welzel, Marco Braun, Stefan Scheller, Sven Issing, Harald Feufel; Robert Bosch GmbH
Driven by miniaturization, cost reduction and tighter requirements for electrical and thermal performance, the use of lead-frame based bottom-termination components (LF-BTC) as small-outline no-leads (SON), quad-flat no leads (QFN) packages etc., is increasing. However, a major distractor for the use of such packages in high-reliability applications has been the lack of a visible solder (toe) fillet on the edge surface of the pins: because the post-package assembly singulation process typically leaves bare copper leadframe at the singulation edge, which is not protected against oxidation and thus does not easily solder-wet, a solder fillet (toe fillet) does not generally develop.
SMTA - Surface Mount Technology Association is a non-profit international association of companies and individuals (totalling 4,000) involved in all aspects of advanced electronics assembly, surface mount and related technologies.
IPC - Association Connecting Electronics Industries is a US-based trade association dedicated to the competitive excellence and financial success of its nearly 2,600 member companies which represent all facets of the electronic interconnection industry, including design, printed wiring board manufacturing and electronics assembly.