[sdiy] No-lead leads

[Seb Francis]

harrybissell wrote:

>No Problem soldering them, Ian
>
>try soldering them in a couple years :^P
>
>H^) harry   (Pb forever)
>  
>

Hi Harry & anyone else who has some knowledge of this Pb-free stuff,

Is it really true that non-Pb parts won't be usable after a couple of 
years?  Is this true for all types of process (e.g. baked matte tin 
plating)?

This would be a real shame - it takes me a long time to get through 100 
resistors, especially the more obscure values.  Am I really going to 
have to bin them after a relatively short time?  Is this just 
speculation, or have some real tests been done over long periods of time?

I'm puzzled because I've seen this problem mentioned before on this list 
but it goes against what most manufacturers seem to be saying
.. a quick google turned up the following quotes from various 
manufacturers amoung the first 10 hits:


"Shelf life remains the same as for current SnPb-plated products."

"As of today we are not aware of any differences regarding shelf live or 
solderability (moist termination) between lead-free and lead-containing 
terminations. Generally shelf live greatly depends on the store 
conditions and environmental influences (temperature, humidity)."

"No. Guaranteed shelf life remains the same as for current SnPb 
products, except for the exceptions mentioned referring to MSL level."

"Is the shelf-life of "lead-free" components reduced because of 
lead-free plating?
Unlikely, in fact it could well be improved, as tin has a slower 
oxidation characteristic compared to tin / lead alloy."

"Are there any changes required in device storage conditions or shelf life?
No."


The only times I have read that shelf life is worse is when talking 
about PCBs, and even then they are talking about automated (e.g. reflow) 
soldering.  I can understand that an old PCB or component might get a 
bit more difficult to solder with age, but with a decent flux core 
solder and a couple of seconds with an iron surely the oxide layer will 
dissolve?


Seb (who did just buy a large reel of Tin-Lead solder just in case the 
new stuff's not so nice to use!)