By John Keller
BOSTON - An aerospace industry group, working under the auspices of the Government Electronics Industries Association (GEIA), will release its guidelines on performance and qualification testing for lead-free solder during the first quarter of 2008, one of the group’s leaders announced in late March at the Military Technologies Conference (MTC) in Boston.
Anthony Rafanelli of the Raytheon Co. Integrated Defense Systems Maritime Mission Center in Portsmouth, R.I., told MTC attendees that the GEIA report, “Guidance Regarding the Performance and Qualification Testing of Aerospace and High-Performance Lead-Free Interconnects,” will be released by 31 Dec. 2007 at the earliest.
The goal of the project is to formulate industry-standard guidance-including test procedures, definitions of military and aerospace operating conditions, industry experience, and lessons learned-for predicting the performance and reliability of electronic systems using lead-free solders that are deployed in military, space, and commercial aviation applications, Rafanelli told the MTC audience.
Although military and aerospace electronics applications largely are exempt from international lead-free solder requirements, Rafanelli pointed out that military systems designers seek to use commercial off-the-shelf (COTS) parts as often as possible, and that means integrating equipment with lead-free solders.
To come to grips with this issue, Rafanelli and his group are gathering information and industry input to help designers use parts and subsystems containing lead-free solder without compromising system reliability.
Lead-free solders present integrators with a host of issues and problems, not the least of which are unknown performance of nonlead solders in harsh operating conditions, as well as the threat of tin whisker growth over time on lead-free solders, which can cause short circuits, as well as other problems and system failures.
Rafanelli and his team are concentrating on how thermal cycling, vibration, mechanical shock, and combined environments such as dust, humidity, salt spray, and other environmental threats will influence the reliability of electronics that use lead-free solder.
“It’s not just lead-free, but a multitude of different alloys we’re dealing with,” Rafanelli told MTC attendees. “Results of a lot of these exotic materials could really creep up on us.”
The GEIA group-which includes members from The Boeing Co., Lockheed Martin Corp., BAE Systems, Honeywell, Curtiss-Wright Controls, Rockwell Collins, and the Aerospace Industries Association of America-is focusing on performance at the interconnect level, and seeks to be as user-friendly as possible “for those not really with the technology,” Rafanelli said.
The report, when issued later this year or early next, seeks to outline the best testing frameworks to account accurately for the operating conditions that electronic systems most likely will encounter in the field.
As much as possible, Rafanelli and his team will include information, test procedures, and knowledge of military operating environments that are already known and encapsulated in existing military and industry standards. “We’re trying to gather what has already been done, and to make sense of it,” he told MTC attendees. “If these established standards have value, then we will use it.”
Even though many military standards exist that directly address test procedures and operating conditions for harsh military environments, Rafanelli pointed out that “lead free is still uncharted territory,” and was never part of programs undertaken previously to formulate military standards and specifications.
“A lot of the mil-specs were based on what we know about tin-lead,” he told MTC attendees. “We would like to come up with mil-spec updates based on what we learn about these new materials.”
Other issues that Rafanelli and his team are considering include are redefinition of solder alloys. Specifically, team members are asking should test procedures take into consideration the surface finishes since they combine with the solder to form the interconnect.
Team members also are asking if they need to clarify what they mean by qualification.
Rafanelli urges anyone in the defense and aerospace industry who has questions, concerns, or comments about lead-free issues and the GEIA group’s work to contact him by e-mail at [email protected], or by phone at 401-842-4850.
