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<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>One thing I know about sharp
corners: On an electrode, a sharp corner will be a preferred place for
electron flow. This is why dendrites on cathodes are to be avoided, and
is why they add “leveling agents” to electro-winning and electro-refining
cells. This is one of the laws of current distribution. Also, if
you make a cathode blank and paint it with dielectric paint, but leave circular
spots of the metal cathode exposed, then when you electro-win metal onto that
blank, you don’t form flat little circular wafers. Instead, you
form what look like metal half-donuts with a flat deposit in the donut hole.
This is one of the preferred ways of electro-winning nickel, and the so-called “nickel
crowns” are used as alloying additions to steel and other metals. I
did a research project on this way back in the day, when they were making
crowns with very sharp edges at the INCO refinery in <st1:State w:st="on"><st1:place
w:st="on">Manitoba</st1:place></st1:State>. We discovered that the sharp
edges were caused by one of the organic additives they were adding to the
electrolyte. Current distribution can be a bit mysterious. This is
also why they put rubber coverings on the edges of cathode blanks in copper
electro-winning – otherwise, a fat cylinder of copper will form all
around the perimeter of the cathode.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>In any case, I would say that if on-board
capacitance or current leakage is a concern, then sharp corners -- both innies
and outies -- are probably best avoided. However, this has nothing to do
with 90-degree angles, just the sharpness of the corners themselves. That’s
why, on my crazy Excel-2003 layouts, I round all of the corners on my traces.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><b><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'> Synth-diy
[mailto:synth-diy-bounces@synth-diy.org] <b><span style='font-weight:bold'>On
Behalf Of </span></b>Kylee Kennedy<br>
<b><span style='font-weight:bold'>Sent:</span></b> Sunday, February 16, 2020
10:16 AM<br>
<b><span style='font-weight:bold'>To:</span></b> Didrik Madheden<br>
<b><span style='font-weight:bold'>Cc:</span></b> SDIY List<br>
<b><span style='font-weight:bold'>Subject:</span></b> Re: [sdiy] 45 vs. 90
degree pcb traces</span></font><o:p></o:p></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color="#222222" face="Times New Roman"><span
style='font-size:10.5pt;color:#222222'>I know the comment about electrons not
liking corners was in jest but you don’t want 90 degree angles on your
PCB designs due to the chance they could become acid traps when the boards are
made.</span></font><o:p></o:p></p>
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<p class=MsoNormal><font size=2 color="#222222" face="Times New Roman"><span
style='font-size:10.5pt;color:#222222'><br>
<a
href="https://electronics.stackexchange.com/questions/445614/what-is-an-acid-trap"
target="_blank">https://electronics.<wbr>stackexchange.com/questions/<wbr>445614/what-is-an-acid-trap</a><o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=2 color="#222222" face="Times New Roman"><span
style='font-size:10.5pt;color:#222222'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><font size=2 color="#222222" face="Times New Roman"><span
style='font-size:10.5pt;color:#222222'>Now back to my TB-303,<o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=2 color="#222222" face="Times New Roman"><span
style='font-size:10.5pt;color:#222222'>Kylee<o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><br>
On Friday, February 14, 2020, Didrik Madheden <<a
href="mailto:nitro2k01@gmail.com">nitro2k01@gmail.com</a>> wrote:<o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Jimmy Moore <<a href="mailto:jamoore84@gmail.com" target="_blank">jamoore84@gmail.com</a>>
wrote:<o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>><o:p> </o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>>(Notable exceptions being RF, high speed, or high voltage layouts)<o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>><o:p> </o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>>This and another<o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>><<a
href="https://electronics.stackexchange.com/questions/226582/pcb-90-degree-angles"
target="_blank">https://electronics.<wbr>stackexchange.com/questions/<wbr>226582/pcb-90-degree-angles</a>><o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>>resource<o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>>debunk the pcb corner myth on EMI effects.<o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>><o:p> </o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>>Is there any other tangible (audible) impact this decision could
have for<o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>>music electronics? I think not, but I'd love to hear from
other more<o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>>experienced engineers on this (hopefully not tiresome) topic.<o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>><o:p> </o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>There's a simple and tangible, although not much audible, reason to
prefer 45 degree angles. They can be routed more tightly on the board. Of
course, 90 degree angles will still be perfectly fine in every non-critical
situation.<o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>/Didrik<o:p></o:p></span></font></p>
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