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Date: Mon, 13 Jul 2015 13:00:13 +0200
Message-ID: <CACwWb3DAv4iDCG+vswVmxWD6uoA8iWia4m82_P30EmnhdgqkbQ@mail.gmail.com>
Subject: Re: [geda-user] PCB interface (ECAD vs. MCAD)
From: "Levente (leventelist AT gmail DOT com) [via geda-user AT delorie DOT com]" <geda-user AT delorie DOT com>
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Modern PCB design tools can calculate trace impedance, resistance etc. You
can create DRC rule that checks your layout vs. impedance, and resistance
for a given net. For this to work, you need -among other property of the
PCB- the thickness of the copper layer.

Moreover, a 3D view of your PCB helps mechanical engineers to fit your
design into their housing.

Lev

On Mon, Jul 13, 2015 at 12:46 PM, Chris Smith (space DOT dandy AT icloud DOT com) [via
geda-user AT delorie DOT com] <geda-user AT delorie DOT com> wrote:

>
> > On 13 Jul 2015, at 10:33, gedau AT igor2 DOT repo DOT hu wrote:
>
> > I think it's PCB is a bit more than 2d - or rather, should be. Ideally,
> it knows the thickness of layers and which of the layers are connected by=
 a
> plated drill. This how blind or burried vias would be possible.
>
> Why does it need to know the layer thickness?  It=E2=80=99s a useful prop=
erty to
> associate with the layer, but I don=E2=80=99t see why PCB needs to know a=
bout it.
>
> > Btw, I see the validity in your MCAD->ECAD idea; actually when I need t=
o
> do draw something mechanical, if it's small, I sometimes just use PCB. I
> shoulnd't, but I'm so much faster with PCB than with librecad for those
> very small things... A typical example is small floorplans, especially if=
 I
> don't need dimension lines (they are expensive in PCB and cheap in
> librecad). My scale is usually 1mm PCB =3D 1m real life.
>
> I guess I=E2=80=99m kind of the opposite.  I=E2=80=99m not a power PCB us=
er: the stuff I
> work on is rarely more than two layers and never larger than Eurocard
> sized.  However it nearly always has some kind of panel mounting.  When I
> start a layout, I nearly always want to start with the mechanical
> components, to say: distribute these switches/LEDS between here and here,
> on 20mm centres.  This is trivial with 2D MCAD, but cumbersome with PCB.
>
> Regards,
> Chris
> =E2=80=94
> Chris Smith <space DOT dandy AT icloud DOT com>
>
>

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<div dir=3D"ltr"><div>Modern PCB design tools can calculate trace impedance=
, resistance etc. You can create DRC rule that checks your layout vs. imped=
ance, and resistance for a given net. For this to work, you need -among oth=
er property of the PCB- the thickness of the copper layer.<br><br></div><di=
v>Moreover, a 3D view of your PCB helps mechanical engineers to fit your de=
sign into their housing.<br></div><div><br></div>Lev<br></div><div class=3D=
"gmail_extra"><br><div class=3D"gmail_quote">On Mon, Jul 13, 2015 at 12:46 =
PM, Chris Smith (<a href=3D"mailto:space DOT dandy AT icloud DOT com">space DOT dandy AT iclo=
ud.com</a>) [via <a href=3D"mailto:geda-user AT delorie DOT com">geda-user AT delorie=
.com</a>] <span dir=3D"ltr">&lt;<a href=3D"mailto:geda-user AT delorie DOT com" ta=
rget=3D"_blank">geda-user AT delorie DOT com</a>&gt;</span> wrote:<br><blockquote =
class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid=
;padding-left:1ex"><span class=3D""><br>
&gt; On 13 Jul 2015, at 10:33, <a href=3D"mailto:gedau AT igor2 DOT repo DOT hu">gedau=
@igor2.repo.hu</a> wrote:<br>
<br>
&gt; I think it&#39;s PCB is a bit more than 2d - or rather, should be. Ide=
ally, it knows the thickness of layers and which of the layers are connecte=
d by a plated drill. This how blind or burried vias would be possible.<br>
<br>
</span>Why does it need to know the layer thickness?=C2=A0 It=E2=80=99s a u=
seful property to associate with the layer, but I don=E2=80=99t see why PCB=
 needs to know about it.<br>
<span class=3D""><br>
&gt; Btw, I see the validity in your MCAD-&gt;ECAD idea; actually when I ne=
ed to do draw something mechanical, if it&#39;s small, I sometimes just use=
 PCB. I shoulnd&#39;t, but I&#39;m so much faster with PCB than with librec=
ad for those very small things... A typical example is small floorplans, es=
pecially if I don&#39;t need dimension lines (they are expensive in PCB and=
 cheap in librecad). My scale is usually 1mm PCB =3D 1m real life.<br>
<br>
</span>I guess I=E2=80=99m kind of the opposite.=C2=A0 I=E2=80=99m not a po=
wer PCB user: the stuff I work on is rarely more than two layers and never =
larger than Eurocard sized.=C2=A0 However it nearly always has some kind of=
 panel mounting.=C2=A0 When I start a layout, I nearly always want to start=
 with the mechanical components, to say: distribute these switches/LEDS bet=
ween here and here, on 20mm centres.=C2=A0 This is trivial with 2D MCAD, bu=
t cumbersome with PCB.<br>
<div class=3D"HOEnZb"><div class=3D"h5"><br>
Regards,<br>
Chris<br>
=E2=80=94<br>
Chris Smith &lt;<a href=3D"mailto:space DOT dandy AT icloud DOT com">space DOT dandy AT iclou=
d.com</a>&gt;<br>
<br>
</div></div></blockquote></div><br></div>

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