RoHS compliant components = shorter shelf life?

[gmr1]

I've seen a couple references to a significantly shorter shelf life in RoHS compliant parts. Anyone have any info on this?

[chi_boy]

I've heard similar thing about RoHS parts and asseblies. I haven't researched, but from talking to the guys at work, eliminating lead from componants and solder has been linked to the formation of "tin wiskers". Without a little bit of lead, the tin will start to grow fine "hairs" that can result in shorts. I don't know if anything is being done to prevent this, or even if anyone remembers the problem. The original research on the subject was done back in the 60's. Hopefully it doesn't turn into a problem later with everyday componants failing because of a 40 year old problem.

[The Tone God]

If OP is asking about the storage life of unused individual parts (i.e. resistors, capacitors, etc.) then the whisker issue is not in play. Whiskers apply to devices assembled with lead free solder. I don't know if the shelf life has been shortened of RoHS components though.

Andrew

[Gus]

http://nepp.nasa.gov/WHISKER/

http://en.wikipedia.org/wiki/Whisker_(metallurgy)

http://tech.yahoo.com/blog/null/50947

http://www.srgclub.org/Wisker_2.html        1946?


http://thor.inemi.org/webdownload/newsroom/Presentations/SMTAI-04_tin_whiskers.pdf

[gmr1]

I actually wasn't sure if what I read was in reference to unused components, or parts in circuit. I'm having a hard time finding my original sources.

Nevertheless, this is interesting info you guys posted - thanks!

If OP is asking about the storage life of unused individual parts (i.e. resistors, capacitors, etc.) then the whisker issue is not in play. Whiskers apply to devices assembled with lead free solder. I don't know if the shelf life has been shortened of RoHS components though.

Andrew

[R.G.]

It's not from whiskers. The materials used for lead free coatings on solderable leads form oxides which are less solderable - and more quickly - than tin/lead/solder plated coatings. They go bad faster.

[Toney]

There also seems to be a lot of variation with components and solder.

I just repaired a RoHS pedal ..... yuck. It was covered with some kind of solder-rejecting force field.
To be more correct, there was huge variation in the re-solderability of the components. I'm not sure if this was due to different 'mixes' used by different manufacturers plus different oxidization rates. The solder spent less time in a liquid state and was horrible to work with- balled up, lower viscosity, different surface tension.