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.
