Anyone here having current problems with ROHS lead free systems?

There were various prior tales of woe or predictions of disaster 
including

- Whisker growth

- Bad solderability

- Unused boards go bad with time
   (eg Peter Crowcroft dumped a stored batch)

- ...

Is anyone experiencing these or other problems in practice?
I'm personally most interested in the first one, growth of 'whiskers', 
as I have boards with highish DC voltage on and relatively small 
clearance distances*, on which Murphy would just love to connect HV to 
lower V in due course.

Present versions of these are not for Europe so ROHS is an option but 
subsequent batches will probably include European markets.

*
This is a non-mains application. Regulatory clearances do not apply.

Voltages are up to about

- 150 VDC between TO220 0.1" pitch pads

or

- About 300v peak-peak AC (trapezoidal waveform) between 0.156" pitch 
connector pads.

- Funny DC / AC mixes in rectifier area.

Worst case seems to be about 0.03" / 0.75 mm between AC and DC lines.
This is believed to be fine in all known practice (10,000+ prior 
units), as long as the tracks stay where they belong and don't try to 
send out tendrils.

There are other larger but smallish clearances between 150 VDC and 5V 
supply etc. Where these get too low I use grounded guard tracks to 
give eg sea breeze environments a run for their money. Would give tin 
whiskers a nasty shock as well.





        Russell McMahon



-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist