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Mail Archives: geda-user/2016/01/26/10:14:03

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Date: Tue, 26 Jan 2016 07:13:43 -0800
From: Larry Doolittle <ldoolitt AT recycle DOT lbl DOT gov>
To: geda-user AT delorie DOT com
Subject: Re: [geda-user] [pcb] poll: burried/blind vias vs. pcb and pcb-rnd
Message-ID: <20160126151343.GA23222@recycle.lbl.gov>
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On Tue, Jan 26, 2016 at 07:46:36AM +0100, Kai-Martin Knaak wrote:
> That said, blind vias are a necessity with any FPGA beyond the 
> smallest size. So the absence of this feature puts a cap to what is 
> possible within the realm of geda. 

Yes, for the largest FPGAs.  In the mid-size range, it's not so much
the number of FPGA (BGA) pins, it's their spacing.  1.0 or 0.8mm
ball pitch is not a big deal with normal vias, but the ever-more-common
0.5mm balls are not possible.  For those you need microvias, a
particular configuration of blind vias.

  - Larry

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