Printed Circuit Board Technology
Damage in Lead Free Assembly

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What? The higher temperatures in lead free assembly may severely damage components and PCB. This is actually more a stress effect than it is thermal degradation, and the reduced ductility of the lead free solder joints compared to SnPb tends to make matters worse.

Lead free compliant/compatible? That label may not be a guarantee. We have seen 'lead free compatible' PCBs fail dramatically in a single mass reflow with a peak temperature of 260°C. This is not common, but you can generally not count on your supplier to test for all relevant damage mechanisms. More...

It worked last time? Maybe you were lucky, or nobody discovered the latent damage yet. More likely, it worked just fine. Now beware how different a 'similar' product often is: Design details that most people never specify in the first place may vary enough to make the difference!

Do you have a problem? Some effects of lead free HASL, mass reflows, wave solder, and repair are obvious. If your boards come out of the oven all black and cracked, it is our expert opinion that you did something wrong (quote). However, some damage is much harder to detect. It may even depend on the component and not show up in bare board testing. More...

Testing? Currently, 'standard' test protocols are at best simple modifications of those used for eutectic SnPb applications. The latter were only empirical to begin with, and some of the 'updates' completely miss the point of concern. In general, most major risks remain untested for. More...

• What can you do?

1) Damage depends on the combination of design and materials selection. Make sure to specify and control all details of either.
2) Lead free capable materials may be more robust but are often also harder to process. You may be worse off with a better material if not processed optimally. Select and qualify PCB supplier with the specific material in mind.
3) Test carefully for all realistic concerns. Do not rely on 'standard' tests.

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