Lead-Free Soldering Development for Assembly of Complex Telecom Boards

摘要

In the framework of the IMECAT project, Alcatel Bell developed technologies for lead-free reflow, wave and selective soldering processes applicable for soldering large and heavy telecom boards with a broad range of components. At first a lead-free solder alloy was selected for the different processes. Based on literature and research results the SAC alloy (Sn/Ag/Cu) was chosen. Different lead-free solder pastes were evaluated. Typical telecom boards have large differences in thermal mass across the PEA. Therefore, a maximized reflow window is necessary. In a preliminary test the process reflow window was determined. One of the more difficult processes is wave soldering since there is a very high interdependency of soldering equipment settings, flux performance and board and component properties. For the evaluation of this process a VOC-freeflux is used. Finally, an existing telecom product as an alternative lead-free version, where all developed lead-free soldering technologies are presented, was realized.