LEAP Working Group Recommends Standards for Lead-Free Future
 The Lead-free Electronics in Aerospace Project (LEAP) Working Group has delivered five in the set of seven standards it is developing to help the aerospace industry navigate its way into a lead-free environment. The working group came together as a joint activity of the Aerospace Industries Association (AIA), the Avionics Maintenance Conference, and the Government Electronics and Information Technology Association (GEIA). Composed of a wide array of stakeholders, from original equipment manufacturers, suppliers of avionics systems, and chip manufacturers to the Department of Defense, the FAA, NASA, and others, the working group was formed in 2004 to address the issues surrounding implementation in 2006 of the European Union’s environmental directives limiting lead and other hazardous substances in electronics.
Though there are exclusions in the directives, and military and aerospace electronics and avionics are exempt from compliance, the working group accurately predicted that the impact of the directives would be quick and significant. The supply chain that feeds the commercial appetite for electronics is the same one that the aerospace industry relies on. The volume of materials and components for consumer electronics vastly exceeds the volume needed by aerospace and defense manufacturers. “We are driven by market forces,” Rusty Rentsch, Director of Life Cycle Management at AIA said. “The aerospace industry represents less than one half of one percent of the total microelectronics that are produced.” Commercial suppliers must necessarily focus on the larger part of their demand, most of which is nonexempt and must be compliant with the EU directives. Noncompliant lead-containing components will eventually prove infeasible to produce and only lead-free parts will be available.
Lead-based solders and coatings have proved capable of withstanding the extreme stresses of military and aerospace applications. Their performance qualities and product life expectancies in such conditions as high altitude, extreme climates, underwater, and the extremes of space are well known. A nonlead alternative, such as pure tin, presents challenges that are only partly understood. New methods must be implemented to minimize reliability and performance risks, such as the anomoly of tin whiskering. Pure tin finishes permit the growth of hair-like, crystalline structures that are electrically conductive and can cause both transient and stable short circuits and potentially catastrophic metal vapor arcs. “There’s definitely a need for more research into the tin whiskering phenomenon. It’s not fully understood,” Rentsch said. Through its Technical Operations Council and Engineering Management Committee, the group is trying to find ways to petition for more research to be done. “We’re working on a Situational Assessment and Gap Analysis on research that is currently going on. We want to identify those gaps and focus additional research in those areas,” Rentsch added.
The LEAP Working Group continues to develop its guidance documents. “ There is an ongoing effort,” said Rentsch, “to transition the current standards into international publications.” The group carries out further exploration of issues that will affect the aerospace industry over the long term. “We need to understand the specific risks the aerospace industry is faced with. We’re going to have to really understand the impact of lead-free solders and their behaviors and what they do to reliability and performance. We’re looking into issues of repairability and sustainability. The process of repairing an integrated circuit board that was manufactured with lead-free solder may be entirely different than that of a board that was manufactured with tin-lead solder,” stated Rentsch. These and other challenges are the focus of the LEAP group as it moves forward to provide the aerospace industry with leadership and information for the lead-free environment.
The LEAP Working Groups’ guidance documents include:
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