The use of lead in electronics has a long history, as a key ingredient in solder alloy, Printed Circuit Boards (PCBs) and termination finishes, to name a few areas.
With a European ban timetabled for July 2006, for most electronic products, the industry has been forced to respond quickly.
FCI’s response has been proactive and sure-footed. A global team was formed in 2000 to address the technical issues and study the impact of the ban on FCI product lines. The two areas most affected are terminal finishes and resin materials for plastic housings.
2000: Planning. Technical representatives from all five divisions of FCI met in January 2000, to plan future strategies that would ensure a smooth transition to lead-free. Projects of the time included a study of tin-alloy plating, especially with respect to bright tin-copper. No practical work was initiated on any of the vendor baths.
2001-2003: On the learning curve.
FCI USA, Inc. commenced the evaluation of lead-free chemistries supplied from Japanese and US companies. The following baths were evaluated over the period 2001 to 2003. - Bright tin-copper: Two vendors. One vendor supplied three versions of baths with modifications in additives - Matte tin-copper: Two experimental baths - Matte tin: Five baths from different vendors containing MSA and non-MSA - Matte tin-bismuth: One experimental bath
The resulting deposits were studied carefully, characterizing properties such as adhesion, appearance and solder joint reliability. Other effects were studied such as whisker propensity. Experiments were performed to determine lead-free re-flow profiles with respect to terminal styles such as press-fit, BGA and SMT. These studies provided a sound basis for understanding lead-free processes and finishes. At this time, we were on a learning curve in respect of lead-free processes, like every other company in the industry.
2003-2004: Commercial evaluation.
Following a period when bath suppliers worked to improve their formulations, several commercial baths were evaluated systematically using a PROCESS DOE. This work formed the basis of a MANUFACTURING DOE. The results were presented at the NEMI Lead-free Conference in Las Vegas in June 2004. The manufacturing DOE was performed on three commercial matte tin baths, one bright tin-copper bath and one standard tin-lead bath. They were evaluated using Bergstik parts. The deposits were tested for properties such as appearance, joint reliability and whiskering tendency. These experiments also studied the effects of two different levels of tin and nickel thickness. A statistical analysis was performed on whisker propensity and the interaction of various parameters. The results were presented in August 2004 at the IPC Conference in Singapore. The manufacturing evaluations were instrumental in qualifying two matte tin chemistries as suitable candidates for Sn-Pb replacement.
FCI’s Lead-Free Technology Solution
FCI has chosen one preferred lead-free finish for all its connector products, that of pure matte tin. It is a choice also endorsed by the other connector manufacturers Tyco Electronics, Molex and Amphenol. A joint paper has been produced by these companies explaining the choice of technology.