Following is from a PCB that I am presently working on. That particular path signals are of 100-400kHz signals. Is there any problem in having routes of this kind?
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3\$\begingroup\$ Why not just route the trace from the pad horizontally left to meat the vertical trace at right angles? \$\endgroup\$– Olin LathropMar 14, 2014 at 16:01
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1\$\begingroup\$ Yes - you will touch off many people's OCD for avoiding acute angles on a PCB. \$\endgroup\$– W5VOMar 14, 2014 at 16:16
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3\$\begingroup\$ Yeah, meat the traces up with ground beef or maybe chicken. Seriously though, ask your fab what they think. They make boards all day long, they'll know what causes bad boards and how to avoid such issues. \$\endgroup\$– dext0rbMar 14, 2014 at 17:08
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1\$\begingroup\$ This question ended up on an AutoCAD site as an example of an acid trap. \$\endgroup\$– JREJun 27, 2019 at 8:56
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2 Answers
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Old timers might grumble about "etchant traps" ... acute angles can hold acid (well, FeCl) long enough to eat through the track - or not, depending on who makes the PCB for you. Consult with them if you are worried.
But I was downvoted for pointing that out in a previous answer, so at least somebody thinks that's no longer a problem.
As far as the signal speed on that trace - nothing to worry about.
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Regarding the signal it doesn't matter. The sharp angle might cause an acid trap, but with the trace width you are using should not be a problem. I would have routed horizontaly from the SMD pad to the vertical trace making a right angle.
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\$\begingroup\$ But isn't good to avoid 90 degree paths? \$\endgroup\$– noufalMar 14, 2014 at 15:23
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2\$\begingroup\$ All other things being equal, 90 degrees is better than the acute angle! \$\endgroup\$ Mar 14, 2014 at 15:42
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4\$\begingroup\$ @noufal, the reason to avoid right angles is to avoid excess capacitance in the trace, and it applies only to high-speed signals (say 100 MHz or higher). Before you start worrying about right angle bends, you'd first want to eliminate the stub in the trace leading to the IC pin, and the big pad on the axial component (resistor?), and use SMT rather than through-hole components to reduce lead inductance. \$\endgroup\$ Mar 14, 2014 at 17:47