Why should one avoid right angles when drawing PCB traces?
There are two reasons.
One is historically right angles make an etch trap where the etchant works too hard and undercuts the inside corner making the trace thinner and more fragile.
The other is that at high frequencies sharp turns make hard-to-predict impedance discontinuities that reduce signal fidelity with small reflections.
Most modern PCB layout software avoids these problems significantly using “mitering” where corners are made with 45° bends, twice if necessary to avoid sharp 90° turns.
These designs used mitering and there are virtually no 90° square corners except a couple of “T” junctions.
