Transition from Sn/Pb to Lead-free soldering (RoHS), possible unexpected problems

Hello,

We intend to obtain CE compliance for our products which means we must be compliant with RoHS. RoHS requires lead-free soldering. I googled about lead-free soldering but I still have some questions for experienced in this field people:
1. Should we change somehow footprints on existing PCBs for lead-free soldering or changes relate with stencil's apertures only?
2. Does anyone know about decreasing of reliability in the long term related with using of lead-free technology? I mean, if device successfuly passed all manufacturing tests, can it go out of order more likely in relation with using lead-free soldering because of aging of solder or something like that? Are there any ways to decrease such consequences?
3. Can we use lead-free PCBs with non-RoHS components?
4. Are there any non-RoHs componets that can't deal with thermal profiles for lead-free soldering? Should I check every component for compliance with lead-free soldering thermal profile?
5. Are there any other unexpected problems (so "called troubles in paradise" or "hidden rocks") connected with transition on RoHS technology? How avoid them?

Below is a 6 year old article, but I suspect it's still pertinent. I've noticed that the boards produced have been less reliable with RoHS solder more prone to cracked solder joints and thermal cycling problems. Isn't government mandated planned obsolescence great! ;-)

**broken link removed**

ads-ee said:

Isn't government mandated planned obsolescence great! ;-)

Click to expand...

I'd rather say it's awful Sometimes the conspiracy theory looks pretty convincing
Thank you very much for the interesting article. Unfortunately, it reveals reliability questions only. I still eager to know any information for questins 1,3..5 from my list.
And one more question for you. Do you have any data (in percent) about reliability decline caused by RoHS solder or it is only your feeling?
Thanks in advance.

There are many challenges in modern electronic production. A few of it are related to RoHS components. Some may be unexpected at first sight.

My personal experience is that most problems are well understood and managed by designers, procuction managers and assembly houses after more than 10 years.

1. I'm not aware of Pb-free specific changes in component footprints. Selection of stencil gauge and possible aperture variation is mostly a matter of component population on a specific PCB and should be always discussed with the assembly house.

3. Some old components didn't tolerate Pb-free solder temperatures, a very few may be still in use. Datasheets and manufacturer application notes should tell. There's an absolute incompatibility of BGA components. Pb-free BGA balls must be soldered with Pb-free paste, SnPb balls with SnPb paste.

5. Just an example of unexpected. Pb-free solder at respective temperatures has an increased ability to dissolve copper, e.g. very thin wires or via throughplating. Beware of excessive solder times e.g. with hand solder.