Re: gEDA-user: chip scale package soldering (was: dxf again)

[Bob Paddock <bob.paddock@xxxxxxxxx>]

   On Fri, Jul 16, 2010 at 5:28 PM, John Griessen <[1]john@xxxxxxxxxxxxxx>
   wrote:

     Mark Rages wrote:

     On Fri, Jul 16, 2010 at 1:35 PM, Armin Faltl <[2]armin.faltl@xxxxxx>
     wrote:
     Oh, those (QFN-like) packages are quite easy to hand solder, except
     for the thermal pad underneath.

   They are a real pain in the butt to get the flux out from under.
   If you are running battery powered stuff, where you want the lowest
   sleep currents, you either don't use QFN, or put a lot of attention in
   to making sure the flux is out from under them.  I've seen currents go
   from over 100 uA to less than my meters can measure after several
   rounds of cleaning, under some Accelerometers and AVRs.
   No-Clean-Flux is an option, but no one likes the looks of a No-Clean,
   because the board does not look clean. :-(

       Sounds like some
     downward pressure on the CS package would be good, right?

   Only if you can guarantee it is evenly applied and your board is truly
   flat.

   --
   [3]http://blog.softwaresafety.net/
   [4]http://www.designer-iii.com/
   [5]http://www.wearablesmartsensors.com/

References

   1. mailto:john@xxxxxxxxxxxxxx
   2. mailto:armin.faltl@xxxxxx
   3. http://blog.softwaresafety.net/
   4. http://www.designer-iii.com/
   5. http://www.wearablesmartsensors.com/


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