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Whenever I come across this situation:

unrouted

I feel a strong urge to make a T - joint like this:

routed

However 90 degrees are usually frowned upon. As such what's a better alternative to this T-joint?

If I follow Tyler's suggestion, I'll get this:

acute angle

However this contains an acute angle which is even worse.

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    \$\begingroup\$ Possible duplicate of Why is there such a strong preference for 45 degree angles in PCB routing? \$\endgroup\$ – Tom Brendlinger Jul 29 '16 at 13:51
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    \$\begingroup\$ In general, 90 degrees connections are not that bad (from a electrical or electromagnetic aspect), neither for manufacturing these days. \$\endgroup\$ – Haris778 Jul 29 '16 at 13:51
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    \$\begingroup\$ Nothing wrong with a T joint. The electrons won't discriminate against them \$\endgroup\$ – bitshift Jul 29 '16 at 13:58
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    \$\begingroup\$ Thanks guys, for your inputs. I am going ahead with a T Joint. Less headache and looks cleaner as well. \$\endgroup\$ – Whiskeyjack Jul 29 '16 at 14:05
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    \$\begingroup\$ Everyone is approaching this from a pure electronics standpoint. Allow me to bring in a mechanical engineering consideration into play: If the board will undergo a lot of thermal cycling (or any mechanical cycling if it's a flex circuit), sharp internal corners on the copper traces (like in 90 degree or acute angles) will develop stress concentrations at the interior angle and will be prone to develop fatigue cracking that could eventually sever the trace. For many applications, this is not a concern at all, but if there will be any source of stress cycling, it's an important consideration. \$\endgroup\$ – Tristan Jul 29 '16 at 15:08
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There's nothing wrong with a T joint (with two 90° angles).

But if you really want to avoid it, it might be possible to route the entire line through the pad:

route through pad

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Why not take the track point from the resistor pad?

Apologies... my KiCAD is broken (recompiling now)

enter image description here

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Do not use Tyler's suggestion. You never want to have acute angles, as you seem to know already.

There really isn't anything wrong with T-junctions, especially if you use "teardrops" (or fill in the 90-degree corners):

enter image description here

Personally I just use "Y" junctions, which only have one 90-degree corner:

enter image description here

Take your pick, but don't use Tyler's suggestion. Acute angles can trap etchant which can eat away at the copper over time. This isn't as much of a problem nowadays but it's still best practice to avoid such routing.

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  • \$\begingroup\$ Thanks a lot for posting the answer. Can you please explain which one is trace? blue one between red boundaries or the red ones themselves? \$\endgroup\$ – Whiskeyjack Jul 29 '16 at 14:42
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    \$\begingroup\$ Also, red on blue (or vice versa) is harsh to look at. \$\endgroup\$ – Dennis Williamson Jul 29 '16 at 17:16
  • \$\begingroup\$ It looks like blue is copper and red is bareboard/keepout/lack of copper. \$\endgroup\$ – scld Jul 29 '16 at 17:22
  • \$\begingroup\$ Sorry guys, these are screenshots of an actual board I'm working on, and those are the default colors. I have a bottom layer pour (the large blue areas) and the thinner blue areas are the bottom layer traces. The red is just you seeing through the clearance between the pour and the traces and seeing the red top layer copper. \$\endgroup\$ – DerStrom8 Jul 29 '16 at 18:40
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Have an acute angle (or 90°) on a PCB is a problem if the junction drive high frequency signal (like communication buss) or a great current amount. This two cases will cause some ECM issue. Otherwise, it's okay to have T junction.

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    \$\begingroup\$ Enterprise content management issues? \$\endgroup\$ – bitshift Jul 29 '16 at 17:44
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You can probably get away with 90-degree intersections until you need really thin traces or are routing rf signals. However, this is considered bad practice and I recommend avoiding it.

The other answers are correct; route through pads or add fillers in the inner angles of 90-degree intersections.

Another thing I do is to place an appropriately-sized via at the intersection. Make sure the ring around the via has enough copper to handle the trace's current.

Oh, and don't do this with high-frequency signals :)

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