group buy for homebrew CPUs?

Dave McGuire mcguire at neurotica.com
Sun Aug 13 09:09:54 CDT 2006


On Aug 12, 2006, at 4:37 PM, Jeff Walther wrote:
>> Yup, get ready to solder .2 mm balls on 800 balls BGA.
>> Get your toaster-oven ready ;-)
>
> BGA components have a specification for the clearance between the chip 
> package and the circuit board after soldering.   I don't think you 
> could meet that just by putting the thing in the oven.

   Very true...but I've looked far & wide for a reason for that 
specification to exist, and have found none.  The only thing I can 
think of is the possible flattening out of the balls causing them to 
short against adjacent ones...but is that really possible?  Not sure.

> I don't know how one reballs BGA components though.  Anyone care to 
> explain?

   One "reballing" kit that I've seen has very thin metal "masks" which 
you place over the chip, and you slather solder paste through that with 
something that looks like a squeegee.  It's similar to applying paste 
solder to a PCB with a stencil.  I don't know how effective that method 
is.

              -Dave

--
Dave McGuire
Cape Coral, FL




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