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Re: Improving usability of KiCad


On 10/11/2010 2:29 PM, Brian F. G. Bidulock wrote:
> Alex,
> On Mon, 11 Oct 2010, Alex G wrote:
>> Please guys, stop arguing. I agree with changing the base unit system to
>> metric, and I have already voiced that opinion. No one tried to chop my
>> throat. If it makes sense to switch to metric why not do it?
>> The real question is wether it makes sense.
> I have several 1000-ball BGAs on a metric pitch.  Every other ball is off
> its position by part of 1/10000th of an inch.  No problem?  Well when
> pulling dogbones for BGA breakout, I wind up with about 1000 0.1mil segments
> connecting the imperial gridded vias to the imperial gridded balls.  So
> I tried unlocking the 45-degree tracks pulling slightly off 45-degrees so
> that there were no 0.1mil segments.  Instead I got 1000 DRC errors (yeah,
> its tight in there), and a thousand 0.0mil segments.  Then there is the
> performance problems associated with drawing thousands of 0.1mil or 0.0mil
> traces.  Hard locking to a 10 nanometer minimum grid would remove all these
> problems.  Any time pads, pins or lands are on a metric pitch, the same
> problems arise.
> The maximum precision allowed by RS-274X is 6.6 for metric, so it makes
> sense to use 1 nanometer as the internal unit.

I vaguely remember this conversion but I don't remember these two reasons being
part of the discussion.  If I recall, it was primarily about rounding when
switching between metric and imperial at the UI level.  Not that the rounding
problem isn't annoying, it is.  Your first issue is very serious problem that
should be addressed.  I don't believe that PCBNew plots use 6.6 resolution (
for some reason 4.3 sticks in my head but it has been a while since I have
looked at this code ) so it is less of an issue in this case.  Before someone
gets upset, I'm not suggesting that PCBNew should not support the maximum
resolution of RS-274X, I'm merely commenting that it currently does not.


> --brian
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