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Message-ID: <4ED5788F.7040600@ecosensory.com>
Date: Tue, 29 Nov 2011 18:27:59 -0600
From: John Griessen <john AT ecosensory DOT com>
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To: geda-user AT delorie DOT com
Subject: Re: [geda-user] Re: I won't do BGA's
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Reply-To: geda-user AT delorie DOT com

On 11/29/2011 03:02 PM, Karl Hammar wrote:
> There is a reference to [3], which is said to show that with suitable
> layout one can get a stand-off distanse of 75-100um.

So, the layout can control the standoff height?  By controlling
the volume of solder paste in an area, the chip will float off by
enough distance to allow flushing flux away?  Hmmm.  Sounds like
it might require depth controlled paste stencils -- where the thickness
of the stencil varies -- they etch the stencil to different thicknesses
to get things like that tuned up in production.

BGA's sound easier to get right.  Just control the area of the pads
and solder mask openings.