[Robotgroup] lead free soldering advice

[douglasee at att.net]

another interesting feature of RoHS is "PCB free" water-based electrolytic capacitors.

the first few designs that got into the field wound up exploding after a few years on service. Dell, HP, IBM, NCR, Wincor, just about everybody got snagged by this problem.

The water-based electrolytic has a tendency to express hydrogen gas over time, especially if the operating temp exceeds 50 C. These caps then start to expand until they look like ball-park franks in the microwave. As the hydrogen is released, the value of the capacitor starts to change drastically.

This is what happens when you get "design by legislation"

-de


-------------- Original message from Edwin Wise <edwin at simreal.com>: -------------- 


> 
> On 24 May 2007, at 2:21 AM, Ed Xavier Gonzalez wrote: 
> 
> > Makes me wonder why European manufacturers are trying so hard to push 
> > RoHS so brutally, specifically when it comes to lead. 
> 
> Yeah, it's not going to be pretty with electronics failing all over. 
> The whiskers are mostly a problem with analog or low-voltage, 
> delicate systems... they are extremely fine! But dang, they can grow 
> _long_ too (I saw pictures). Amazing stuff. 
> 
> > If corrosion begins forming immediately after the lead-free solder is 
> > applied, then an overcoat of lacquer or some other clear surface 
> > treatment that prevents oxygen from passing through would need to be 
> > applied... 
> 
> Apparently overcoating doesn't work either (according to this article 
> I read). They fingers grow anyway, and they are so sharp they just 
> burrow their way through. As far as I've heard, there's no cure yet, 
> though the industry is working with different solder formulations to 
> try and minimize the problem. 
> 
> Edwin! 
> 
> 
> 
> _______________________________________________ 
> Robotgroup mailing list 
> Robotgroup at puremagic.com 
> http://lists.puremagic.com/cgi-bin/mailman/listinfo/robotgroup