Screaming Circuits: RoHS temps may still kill RoHS parts


RoHS temps may still kill RoHS parts

I've written about a few cases where alleged RoHS compliant components don't always hold up in the face of RoHS reality. Our friends over at ECD have been studying the problem and coming up with solutions to best eliminate the problem. They make thermal profilers for reflow ovens. We use their products here at Screaming Circuits and that's one of the reasons we have such good reliability with our assembly work.

If you're going to the APEX show in Vegas an the end of the month, you can drop in and see them in booth #1628. Until then, here's a bit they have to say on the issue:

EMS Alert: Would you rather be part of the problem, or part of the solution? Elevated Pb-free temperatures can cause hidden damage!

The new IPC standard released Dec 08, Classification of Non-IC Electronic Components for Assembly Processes, J-STD-075, calls for thermal classification of components, and recommends a marking system to help contract manufactures recognize component temperature limits during the soldering process. The release of the standard follows a comprehensive study by IBM on this issue, and substantiates what we at ECD have recognized from field reports.

The IBM study shows that these higher temperatures are dramatically shortening life expectancy of components, especially more sensitive passive components. Failures don’t show up during initial test, but much later on in the product’s life – often six months to two years later, and well below forecasts that drive pricing and warranty policies. ALL parts have temperature limits; and until we take the time to profile the process to which we subject these parts, we can’t know if we cause harm or not. The IBM study has done much to provide such characterization, so there is little excuse to proceed in the dark.

We have, over the past year, written several articles (see links below) pointing out that with increased solder process temperatures, specifically for lead free solder, it is more critical than ever to make thermal profiling a process that takes into consideration the most sensitive of components. A comprehensive program is needed, and ECD has moved in that direction with our Thermal Quality Management (ThQM™) Program. We think this will give the industry the knowledge and tools to look at ALL components in the comprehensive light necessary. Equally important, it introduces a program and method of dialog between OEM and EMS provider on soldering process issues. Finally, in keeping in the “standards” vein, the Thermal Quality Management Program suggests a process, with corresponding checklist, to assure both OEM and EMS provider that no damage was done during the soldering process.

An ECD representative will make an APEX presentation on Thermal Quality Management on Wednesday, April 1, at 12:30 at the combined Circuits Assembly/Global SMT & Packaging Booth # 1383/1385, and will be available for questions at our own ECD Booth #1628. You can also visit www.ecd.com for more details on ThQM™ and to sign up for free online classes on this subject.

ECD Articles:
Thermal profiling optimizes printed circuit board assembly
Thermal profiling: A key element of process control
The IBM study

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