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Green solder blowback

Mar 14, 2011

Blowback is a CIA term that basically refers to ”unintended consequences” as a result of some previous action! The motivation of said action may have been well intentioned, however the results can be anything but, depending on many and diverse factors. Contrary to popular opinion not all “blowback” is manifested by the United States Central Intelligence Agency. In fact several European agencies have caused some severe blowback in the realm of technical electronics that has potential to indirectly affect marine electronics.

I’m referring to the European Union’s mandated Waste Electrical and Electronic Equipment (WEEE) and Restrictions on Hazardous Substances (RoHS). One big unintended consequence of these laws is the plethora of problems with process and hand soldering brought on by the removal of lead in solder. For the past 60 years, reliable attachment of electronic components has mostly relied on a mixture of 60 percent tin and 40 percent lead alloyed solder. Not only has this proven to be an optimum solution to help ensure long and trouble-free operation of circuits, but it also made it easy for technicians to spot potential defective solder joints by simply eyeballing them. Good solder joints were smooth and shiny, while marginal solder joints were usually rough in texture and dull in reflectivity. These improper solder attachments could be remedied by simply reheating them with a soldering iron during a touch-up operation. I can’t count the number of times that I was able to repair broken electronic circuits by looking at the printed circuit board for bad looking solder joints and reheating them. But this technique is now no longer useful with lead-free connections.

Lead-free connections usually use solder that substitutes silver-copper or copper alloys for the lead, but this substitution comes with some added problems, some unintended consequences. First, the new solder alloys require higher temperatures which are the enemy of electronic components. Second, once the soldering is done the resulting connection appears dull and grainy which makes it hard to determine if it is a high-quality connection. Third, there is a real problem with tin whisker growth from solder alloys containing silver, and these whiskers can eventually short out components and circuits. So you see that there can be some serious potential problems being caused by lead-free solder.

It should be mentioned that military, aviation, and marine electronics were exempted from WEEE and RoHS, which brings us to the biggest unintended consequence of all: lead-free products unknowingly are being incorporated into these exempted categories of electronics. According to Kirk Armstrong of China Lake, Naval Air Warfare Center in California’s high Mojave Desert, this has been happening in military electronics since 2007. GPS data from a telemeter was lost during a captive carry flight over China Lake test ranges. Failure analysis identified the source of the problem as a printed circuit board embedded in an assembly fabricated by a vendor in Ireland. The sub-assembly vendor who supplied the GPS system was surprised by the discovery that the board was fabricated using lead-free solder alloys in accordance with EU RoHS regulations.

I was surprised to find out that lead-free soldering is even incorporated into marine safety equipment such as EPIRBs and PLBs. I think that this is happening for basically two reasons; everyone these days wants to jump on the green bandwagon and also due to logistical concerns. Just find a current electronic component catalog and see how hard it is to find standard components and solder. And if you can find them, they cost more. Another reason was mentioned in our defective GPS example, sub-contractors and commercial off-the-shelf equipment. Knowledge and information is always a valuable resource that can come in handy at critical and inopportune times. If you happen to suffer from a future electronic failure when everything else seems good then it could be due to lead-free soldering!

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Fredrick Gary Hareland holds an AAS degree in rescue and survival operations and in avionic systems technology and is a certified marine electronics technician and NARTE certified telecommunications technician. He has served in the U.S. Navy, Coast Guard, the Military Sealift Command-Pacific and has worked for Maersk Line Limited and Norwegian Cruise Line. Hareland currently works at China Lake Naval Air Warfare Station as a microwave-communications technician. He lives in Ridgecrest, Calif.

More articles by Fredrick Gary Hareland:
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