Such is the size of the lead-free challenge that a number of connector manufacturers have decided collaboration is the best way forward. Since November 2002, some major connector suppliers have been working together with FCI, not only to pool test resources and expertise but to develop a common set of terms.
It has been vital to ensure that everyone - customers and suppliers alike - is talking the same language, to avoid confusion when describing product or test data. So far, the group has agreed on definitions for several key terms that are used in the effort to eliminate lead from products. For example, all have agreed on a definition for “lead-free process capable”, which is:
Parts are considered lead-free reflow process capable if they suffer no loss of form, fit or function after exposure to the peak reflow temperatures specified in IPC/JEDEC J-STD-020B.
To give another example, the following definition for “whisker-free” has been developed:
A terminal finish is considered whisker-free if after exposure to environment the maximum whisker length is less than 50 microns. The environmental exposures must include heat age (50oC ± 5oC, uncontrolled humidity, 6 months), heat and humidity (52oC ± 5oC, 90% ± 5% relative humidity, 6 months) and room temperature storage (23oC ± 5oC, 6 months).
The group has also worked on common test methodologies, to provide customers with consistency in the data provided by suppliers. For example, standard methodologies for assessing effects like tin whisker formation (in connector terminal finishes) or the heat resistance of connectors to lead-free soldering.
A number of key issues have a bearing on the elimination of lead from connectors, such as the preferred lead alloy substitute as well as useful approaches to labeling and part numbering. Tackling these questions has been a focus of the collaboration, an effort that has produced a number of proposals and a paper “Pure Tin – The Finish of Choice for Connectors”, co-authored by group members and presented at the October 2003 IPC/JEDEC Lead-free Conference in Frankfort.
The group works with a number of international standards bodies and industrial consortiums to develop realistic lead-free test methodologies and qualification requirements.
