Usually I route my PCBs never making a 90º turn as best practices recommends, but sometimes there are points were 3 traces must intercept, if I always do 45º turns, in this intersection will be a 90º turn, so is it ok, or there is a better way of doing so?


The 90º intersection will not be a issue for most traces. If your trace is very thin (< 15 mill) and/or the PCB boards aren't being professionally manufactured you can use mitered traces (chamfer) as helloworld922 pointed out. Adding chamfers will eliminate the 90º intersection and help to strengthen the trace. For high frequency traces (> 1GHz) it also helps reduce signal reflections.

pcb chamfer

The lines have constant impedance along their length regardless of routing which is a highly desirable property. Note: this is less true at the highest frequencies where abrupt corners in a track also cause reflections. For this reason most PCB designs employ mitred (45°) or chamfered (curved) corners.

There are other methods to help prevent signal reflections, like the following image shows:

Miter PCB Trace PDF

The image above is from Microstrip, Stripline, and CPW Design.

For more reading material, take a look at 90 Degree Corners: The Final Turn.

  • \$\begingroup\$ "The same holds for bends with angles \alpha greater than 90 degrees" What do you mean by that? 180>90 so that would hold for all wires/traces as wires/traces/are made from smaller straight pieces. \$\endgroup\$ – Gunnish Jan 7 '13 at 9:46
  • \$\begingroup\$ @Gunnish It means that a bend of 90 degrees or more will cause reflection for high frequency signals. An example is the 135 degree angle in Camil Staps's answer Although like text is specifically talking about a bend, not an intersection like the OP's question. \$\endgroup\$ – Garrett Fogerlie Jan 7 '13 at 9:54
  • \$\begingroup\$ Also, that snippet is from a document that is discussing microstrip design. This is not exactly the same as what the OP was posting, but I thought it was interesting to add mostly for the increased inductance notch image. \$\endgroup\$ – Garrett Fogerlie Jan 7 '13 at 10:06

You can add some internal chamfers to the PCB trace.

chamfered traces


Either straight 90 degrees or added mitres is fine. One thing to avoid is angles of less than 90 degrees, like the internal angles in a 'Z', or the "increased inductance" example in Garrett's answer.

These are sometimes called "etchant traps" and cause manufacturing problems with some board manufacturers. For a hobbyist PCB I wouldn't worry too much, but if you were building a million I would re-design to avoid them.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.