New environmental standards are restricting the use of lead and other hazardous substances commonly found in electrical and electronic components possibly complicating and hindering Naval aviation readiness levels.

The lead-free restrictions recently put on micro-electronics and circuit board soldering methods comes from the Reduction of Hazardous Substances (RoHS) directive from the European Union restricting the use of six substances commonly used in electrical and electronic equipment – lead, cadmium, mercury, hexavalent chromium, polybrominated biphenyls and polybrominated diphenyl ethers.

China took similar steps to reduce hazardous pollutants when they enacted RoHS initiatives March 1, 2007.

Why do these EU and Asian directives matter to the U.S.? Because most of the electronic equipment the U.S. buys comes from Pacific Rim nations where these items are produced. These new environmental regulations were designed to impact the massive amount of throw away electronic consumer items that are clogging landfills worldwide. When cell phones, computers, televisions and other household electronic devices degrade, the chemicals that makes up the solder leach into the soil contaminating the area.

“Lead was introduced back in the 1940s to help the solder flow better,” said Bob Maskasky, an avionics engineer from Fleet Readiness Center South East in Jacksonville, Fla. “Engineers found than without lead, pure tin solder had a tendency to grow thin strands from the solder joint that could grow over the years and cause the circuitry to short out. Traditional tin-lead solder is 63 percent tin and 37 percent lead.”

Cleaning up the environment is a good thing. Most would agree. But what are the implications to the aerospace industry in general and specifically the Navy’s aircraft fleet? How will it change the way DoD tests and maintains aircraft systems? Are there already lead-free parts circulating the supply chain? Do engineers have to recertify and redesign systems that are already in use? How much money will it cost?

Military and defense contractors are exempt from RoHS but aerospace shares a common supply chain with the rest of the world. The DoD accounts for less than one percent of the world’s electrical and electronic component market. Because of this phenomenon, legacy products and materials are being phased out with little to no regard to military and aerospace electronics, and are being replaced with lead-free equivalents.

“The typical life of commercial electronic devices is three to seven years compared to decades for DoD systems,” said Lloyd Condra, Chairman of the Lead Free Electronics in Aerospace Project (LEAP). “In fact, we’re seeing device manufactures optimizing the design of microcircuits to wear out in that same timeframe.”

NAVAIR spends approximately $1 billion dollars a year on software development.
The government cannot throw that huge investment away every time a new product becomes available. When the costs to re-certify flight critical systems are factored in, it’s obvious that the same solutions available to the throw away consumer market aren’t an option to the military. In fact, the Space Shuttle is still flying with 286 processors. The cost to re-qualify newer products wouldn’t justify the improved performance by the time the shuttle retires in 2010.

This is a big problem because DoD doesn’t yet fully understand what happens when the new components are exposed to the volatile environment of flight. Issues, like tin whiskers growth, changes in reliability and different solder temperatures, all have to be assessed before the new lead free microcircuits are introduced to the system. In response to these challenges, both industry and government have been scrambling to understand the physics and arrive at a consensus on policy.

In typical engineering fashion though, you assemble 10 technical experts and you’ll get 11 opinions, said Bob Ernst, Joint Council of Aging Aircraft Chairman.

The response from both industry and government has been overwhelming. After spending the first couple of years in denial, several groups are now attacking the issues and sharing technical data on an unprecedented level. Groups such as LEAP, the Government Engineering and Information Technology Association (GEIA) and the Joint Group for Pollution Prevention (JG-PP) are sharing limited test data and trying to assist both government and industry program teams with the transition.

“This may not be the first group to assemble the world’s experts from industry and government to conduct research and draft policy, but it’s not typical,” Ernst said. “In fact many people are still in denial. The fact that RoHS targets lead is admirable, but when they exempt batteries, which account for almost 80 percent of the lead in land fills, it makes one wonder if the whole thing is nothing more than a political statement.”

Political statement or not, lead free electronics are here to stay and a whole host of technical issues need to be resolved if we are to avoid a major disruption to our supply chains.

Technical Issues

In order to develop a policy that allows for a smooth transition to Lead Free Electronics (LFE), it’s important to understand the technical issues involved.

“The only service to draft a policy on LFE to date has been the Air Force,” said Vance Anderson, from Defense Microelectronics Activity (DMEA), referring to a 2006 memo.

The one page document policy issued by Aeronautical Systems Command at Wright-Patterson only alerted programs that many systems were converting to lead free. That’s about all the information that was available at the time. In order to draft more detailed planning guidance, the joint technical community needed a consensus for the best way to handle the myriad complex technical issues.

Many Solder Types
When the RoHS documents were first drafted, industry responded by developing and researching a whole series of solders. At last count there were 279 different alloys, all of which have slightly different properties.

“We could spend the next 100 years testing and characterizing different alloys and still not have all of the properties documented,” said Bob Ernst, Joint Council on Aging Aircraft, Chairman.

By sharing test results, industry is leaning to a series of alloys called SAC. SAC stands for the three ingredients in the alloys (Sn for tin, Ag for silver and Cu for Copper) The most prevalent of the SAC alloys is SAC 305 which is comprised of 96.5 percent tin, 3 percent silver and .5 percent copper, said Dr. Bob Maskasky, from Fleet Readiness Center-South East in Jacksonville, Fla.

The new alloys are not one for one drop in replacements. In fact, the Office of the Secretary of Defense policy documents presented at the LEAP Working Group meeting in Crane, Ind., stated that there were no known (drop in) qualified replacements for tin/lead solders.

The most obvious difference is that the Lead Free Solders have a higher melting point. Sixty-three percent tin/thirty-seven percent lead solder has a melting point of 183 degrees Celsius, and the SAC alloys melt at temperatures 30 to 40 degrees Celsius higher, around 215 to 227 degrees Celsius.

“This temperature change could show up when the technician tries to solder a lead free component on a board with tin/lead parts and the surrounding parts become a pile of goo,” said Andy Ganster, from Naval Surface Warfare Center Crane, Ind.

The reliability of the new alloys is also a big unknown. The Joint Group on Prevention of Pollution (JG-PP) tested the three most common alloys in 2003 – stabilized tin-copper+Ni, tin-silver-copper, and tin-silver-copper-bismuth. The results of the JCAA/JG-PP Lead-Free Solder Project do not provide definitive answers on the future use of lead-free solder in high-reliability electronics for military and aerospace. One of the fallouts of this testing was that the new lead free solders are more susceptible to vibration. We know that transition to lead free solders is going to effect reliability. We don’t know the overall impact on weapons systems reliability. Either way, the new reliability needs to be inserted into the industry standards for calculating reliability so that weapons systems designers can adequately assess the impacts.

Tin Whiskers:

Even though lead was added to the pure tin solders in the 1940s to improve the solder flow, it wasn’t until the lead was removed that engineers noticed that small “whiskers” started growing from the solder joints. These whiskers, only 1-2 microns, can grow over time and cause the electronic device to short out and fail.

“We don’t really understand why they grow or what causes them to grow,” said Dr Stephan Mescher from BAE in a recent LEAP working group presentation. “Research on tin whiskers growth has been going on for decades but we still don’t know why or what makes the tin whickers grow.”

It has also been observed that these whiskers growth is accelerated in a vacuum which probably lead to NASA’s decision to not allow any Lead Free components in the Space Shuttle.

But help is on the way. Some of the NASA studies from the 1980s have been dusted off and re-evaluated. Because the samples were saved, it was possible to see if the whiskers continued to grow over the last 20 years. Interesting, some of the configuration showed no additional growth. It might be possible to make small changes in the solder composition or in design geometries and mitigate the whisker growth.

But for systems already in production, conformal coating was initially thought to eliminate whisker growth. Initial testing showed that no existing coating eliminated whisker growth, but coatings could stop the whisker from re-entering the electronic device.

“As the whisker tries to re-enter the conformal coat, it has a tendency to buckle,” said Jay Brusse, a senior components supporting NASA Goddard. “We still have the potential of two whiskers to intersect, but that probability is greatly reduced.”

With the potential to have so many technical issues affecting the reliable use of lead free electronics, it’s been difficult to come to a consensus on the criticality of these issues.

“It’s easy to write documents, but if you want them to mean anything, you have to make sure that they address the technical issues,” Ernst said. “The last thing any of us needs is more vague plans that don’t mean anything.”

After several years of work, we finally have enough information to start finalizing real guidance to our program teams.

“People have to understand that the documents available today aren’t 100 percent complete and will have to be modified as technical issues are resolved and additional ones are discovered,” Ernst said. “At least it’s a start.”

As Sir Winston Churchill said after the Battle of El Alamein, “I’m not sure that it’s the beginning of the end, but I do know that it’s the end of beginning.”

Now we have to translate those answers into documents that our program teams can utilize.

LEAP

Many of the various working groups dealing with Lead Free Electronics have spent a tremendous amount of time and energy trying to find ways of mitigating the technical issues.

All of the research in the world means nothing if there is no way of translating the results into documents that our acquisition and support teams can use, said Bob Ernst, Joint Council on Aging Aircraft Chairman.

In the past, DoD personnel would write a Military Specification that covered the way a program should be implemented. With the emergence of Commercial Off –The-Shelf systems and the drive to reform acquisition in the 1990s, the shift was made to commercial standards to define what and how we procure and support systems.

“Getting a consensus set of documents is sometimes a long and frustrating process,” Ernst said. “But once you have that consensus, its easier for our program teams to place those requirements on contract.”

Cost is a big driver as well.

“[The military] absolutely has to have a standardized approach with all of industry,” Ernst insisted.

Studies by the University of Maryland Center for Advanced Life Cycle Engineering (CALCE) show that for industry to make the transition to Lead Free Electronics it may cost between $5 and $10 million dollars. For a typical board manufacturer that could increase the cost of their product by about 1 percent.

“If that same contractor has different processes and requirements from Lockheed-Martin, Boeing, Raytheon and other companies, that cost could increase to 5-6 percent,” said Peter Sandborn, from CALCE. “If we can’t agree on standard processes to qualify Lead Free Electronics, that number could double or triple.”

With Naval Aviation spending almost $500 million per year on avionics spares and repairs, those costs would be significant.

But help for our acquisition teams are on the way. The LEAP working group and GEIA have developed a series of documents to guide programs with the transition to Lead Free. The first document, published in 2005 is the Program Managers guide and can be found at the AIA Web site (http://www.aia-aerospace.org/).

“Our typical response to a new requirement is to ask each acquisition program for a plan,” Ernst said. “But without telling programs what attributes need to be addressed, we don’t really buy much. The Program Managers Guide provides industry practices on how to screen parts, perform configuration management and conduct testing.”

Once we started learning more about the transition to lead free electronics, it was obvious that we needed to create a series of documents that can go into more detail on each of the various technical issues, Ernst said.

To date, three documents have been released

GEIA-STD-0005-1, “Performance Standard for Aerospace and High Performance Electronic Systems Containing Lead-free Solder”
This document specifies that users develop and implement written Lead Free Control Plans (LFCP). The purpose of the plan is to document processes that assure the Plan owners, their customers and all other stakeholders that aerospace and high performance high-reliability electronics systems will continue to be reliable, safe, producible, affordable, and supportable.

GEIA-STD-0005-2, “Standard for Mitigating the Effects of Tin Whiskers in Aerospace and High Performance Electronic Systems”
This standard provides a framework to execute certain levels of control according to the criticality and utilization of a system. Appendices to the standard provide guidance and insight into addressing risks associated with tin whiskers.

GEIA-HB-0005-1 “Program Management / Systems Engineering Guidelines for Managing the Transition to Lead-Free Electronics”
This handbook provides assistance for programs in assuring the performance, reliability, airworthiness, safety, and certifiability of product(s), in accordance with GEIA-STD-0005-1. The handbook illustrates what concerns should be voiced to ensure the lead-free transition does not have a negative impact to the product. Working with the program manager, the lead systems engineer is responsible for assuring that all system requirements are addressed and verified via design and integration. Hence, the document was generated for both disciplines to use in assuring proper program execution and customer satisfaction.

Documents approved with comments:
GEIA-HB-0005-2 “Technical Guidelines for Aerospace and High Performance Electronic Systems Containing Lead-Free Solder and Finishes”
This document provides technical guidance for the use of lead-free solder and mixed Tin-Lead/Lead-free alloy systems while maintaining the high reliability standards required for aerospace electronic and electrical systems. The document discusses approach for analysis of tests and data; lead-free solder behavior; system level service environments; high performance electronics testing; solder joint reliability conditions; components; printed wiring boards; printed wiring board assemblies; module assembly conditions; aerospace wiring conditions; repair/rework; and modeling/analysis.

GEIA-STD-0005-3 “Reliability Testing for Aerospace and High Performance Electronics Containing Lead Free Solder” (Planned date for initial release by GEIA: June 2007)
The purpose of this document is to provide guidance for reliability testing of aerospace and high performance products containing lead-free solder and a protocol for designing, conducting, and interpreting results from reliability tests. This document will provide a default method for performing reliability testing in the near term. Although several major reliability test programs are nearing completion, some time will be required before the data can be understood and characterized. In the meantime, manufacturers need a methodology to conduct their own reliability given their own unique set of service conditions. The protocol, presented in this document, is meant to be used when little or no other information is available to define, conduct, and interpret results from reliability tests for electronic equipment containing lead-free solder.

GEIA-HB-0005-3 "Guidelines for Repair and Rework of Lead-Free Assemblies Used in Aerospace and High-Performance Electronic Applications" (provisional title)
This will be a document providing guidelines for repair and maintenance of lead-free electronics.

GEIA-HB-0005-4 "Guidelines for Performing Reliability Predictions for Lead-Free Assemblies used in Aerospace and High-Performance Electronic Applications" (provisional number and title)
This document will describe methods of quantifying the effects of lead-free solder on system reliability and certification analysis.

Depots

With changes in environmental legislation affecting so many markets, one has to wonder how the RoHS restrictions are going to impact the armed services’ ability to sustain, repair and overhaul their weapons systems.

The Department of Defense is in a unique situation because even though most airframes may have two or three avionics subsystems changes during their lifespan, those subsystems will still be operational for typically more than a decade. Even considering commercial aerospace and military together, they still comprise approximately one percent of the electronic component market. Most consumer avionics systems are considered consumable, with design life span just a year or two.

“When is the last time anyone repaired the cell phone?” asked Ric Loeslein, NAVAIR Diminishing Manufacturing Sources and Material Shortages (DMSMS) team lead, echoing the market transition to consumable components and systems.

But repair is a big issue to the Department of Defense. The average age of aircraft in Naval Aviation is over 18 years; for the US Air Force it’s almost 24, said Bob Ernst, Joint Council on Aging Aircraft Chairman. Even with the recent increases in procurement, we’re going to have the existing systems around for a long time and the budget reflects that emphasis. Using lead free solders/components in some cases is impractical for repair of legacy circuit boards due to the induced damage from much higher melting temperatures.

“Our Aviation Depot Level Repairables (AVDLR) budget for 2006 was over $2.3 billion with about 35 percent of that going to repair of avionics systems,” said Doug Monin, head, Enterprise Cost Analysis Branch at NAVAIR. “That’s over $800 million a year for avionics when you throw in the costs for the ‘O’ and ‘I’ level labor and consumables, the costs only increase.”

Even if we impact those numbers a slight amount, the strain on existing Naval Aviation budgets is severe.

In addition, the performance of lead free solder alloys in high performance applications such as air and space applications is suspect in several areas including reduced vibration and shock tolerance, and the known but very unpredictable phenomena of “tin whiskers” – small growths that can short a board with alarming unpredictably due to the lack of lead. There are also more than 200 different types of compounds now available as lead free solder.

But how prepared are our depots to mitigate the effects of the introduction of Lead Free Electronics? Do we require huge capital equipment purchases to handle the new solders and processes and, if so, have these increases been incorporated into the procurement budgets?

The Survey

“Back in 2003, we were working with some of the industry experts understanding issues with our legacy avionics systems and the lead free electronics issues kept coming up,” said Mike Whelan, former avionics team lead for NAVAIR’s Aging Aircraft Team. “Industry was just starting to understand the technical issues and definitely focusing on the acquisition/design side, but no one had systemically assessed the impact to the Aviation depots.”

After a series of briefings to the depot leadership, it was decided that the Joint Council on Aging Aircraft (JCAA) should conduct a study to see how prepared our depots were and compare their status to the changes going on in the commercial sector. After surveying the Lead Free Community, the JCAA selected ITB, Inc, a small business in Dayton Ohio to conduct the survey. ITB had a good reputation and had been involved in the testing of lead free alloys for a number of years, Ernst said.

“Lots of folks had ideas on what might potentially impact our ability to repair avionics, but we didn’t see coordination across the depot community”, said Bob Ernst, head of the Aging Aircraft team. “We knew that traditionally, new technology requires a change in publications and training as well as the equipment purchases. What we didn’t know was how far along our depots were in this evolution. With the transition to Lead Free Electronics just beginning, we had a tremendous opportunity to get ahead of the power curve,” said Ernst. “Instead of having 12 different aviation depots/repair centers all develop new training and procedures, we had the opportunity to take the best of breed and develop one product that met the needs all. If you consider that some of the publications are already joint, it’s a no-brainer.”

In addition, avionics repair is sometimes critical at the intermediate level to support readiness levels, increasing the need for getting a handle on the incursion of lead free solder and its potential impact.

The Findings

ITB, along with representatives from each service, made 12 different trips to depot/repair center activities over an eight month period.

“Each survey was preceded by a questionnaire, followed by a review of ongoing study findings before we reviewed their plans and activities,” said Denny Jarvi, Principle Engineering Director at ITB. “Once at the depot, ITB ‘followed the part’ through the entire process from incoming inspection to final assembly and test. The key was to look at the whole process and see where it possible for lead free components and/or systems to enter the depot. We suspected that any dual use components (components that were manufactured for commercial systems like computers) would be the first entry points.”

In fact the team confirmed that the suspected lead free incursion was a reality by finding commercial lead free components in almost every depot/repair center. Anything that is dual use, including UAVs and ground equipment is highly suspect. European source support equipment may be the first system level lead free incursion since RoHS was initiated there, and DoD maintains and repairs it’s support equipment, magnifying the potential sustainment problem.

It wasn’t a surprise that the survey indicated that our depots had some significant issues to address before the transition to lead free electronics is incorporated.

“We didn’t expect them to be ready,” Ernst said. “We were conducting the survey just as the first lead free parts were hitting the system. It’s nice to actually be ahead of change so that we can plan accordingly.”

The results of this survey, presented to the Joint Aeronautical Logistics Commanders in early August recommended several mitigation actions for DoD consideration:.

1) Establish a depot IPT to look at all aspects of implementation. With more than 4,000 soldering stations across the aviation enterprise, it doesn’t make sense to establish a dual repair capability for every system that we repair today. We can’t afford to buy new soldering equipment for every bench in use today. The depots need to look at what lines need to be supported and see if we can’t consolidate repair centers. Much like the consolidation of capabilities being done as part of the FRC process, we need to continue to look at expanding inter service repair agreements and commercial transition.
2) Work with DLA and the supply offices to establish interim procedures for handling Lead Free Parts. The survey pointed out that over 95 percent of our current piece parts come from DLA. If we can work with DLA and establish some type of screening program for incoming parts or revert back to the trusted vendor approach we can minimize the impact of mixed parts.
3) Identify technology that can be used to quickly and easily identify lead free parts. Since the procedures for marking parts are still being worked, the DoD needs a quick and easy tool to check parts from unknown sources of supply and verify that the parts are either eutectic lead or lead free. Many systems exist today, the most promising of which uses X-Ray Fluoroscopy (XRF) technology. The Aviation community has the opportunity to standardize the procurement of these systems with the resultant savings in both development costs and support.
4) Establish common LFE training modules and publications. One of the big surprises from the survey was that initial publication describing the issues with lead free electronics has already hit the street. The Navy micro-miniature manual (NA 01-1A-23 -- Standard Maintenance Practices, 2M) was revised in October of 2006 by NSWC Crane and already has some preliminary information on lead free systems. It is evident that this data will have to be revised as more is learned from the continuing studies, but the fact that the publication hit the streets before the hardware showed up is unprecedented.
5) Capture data on Lead Free Failures. Lots of testing has been done at the component level, but almost no information has been collected at the weapon systems level. The aviation community needs to perform full systems test and then establish a data collection system to record failures on lead free systems once they hit the fleet.

“A daunting challenge? Perhaps,” Ernst said. “We must remember that we still have some time and view this as an opportunity to attack an issue before it cripples our ability to support the war fighter. A decade ago, if you had suggested that we could change the culture and combine our depots and “I” levels into a single entity, people would say that it could never be done. But the Fleet Repair Center concept is alive and well today. Just as we handled those challenges, we must break down stove pipes and meet this new one.”

(Information provided by the Joint Council on Aging Aircraft)