Why we prefered 135' routing?

[Parthipan]

Why we prefered 135' (45') routing instead of any angle routing (ie. 145', 150', 160,)?
Is there Any issue from manufacturing wise?

 

[abhi002]

plz refer the attachments,they clearly explains ur doubts

 

[purplerain0724]

Good question. I asked my professor the same question. He said that nowadays there are no real grounds why PCB trace routing would be limited to 45/90/135 degrees. It's a power of tradition.. Long ago (like, in the 1970s) photoplotting devices had problems with forming any-angle traces due to some mechanical issues (like, it was a problem to rotate the head at angle different from 45/90 degrees). And they decided to unify trace angles.
Modern photoplotters can perform traces at any angle.
Still, in majority of PCB suites (Altium Designer, Cadence Allegro, etc.) autorouters are limited to 45/90 angles. Out of all PCB suites I worked with only TopoR can naturally perform any-angle autorouting which I consider a great advantage.

 

[cyberrat]

AFAIK Cadstar can also route at any angle, it also has river routing that ignores the above angles and routes point to point around obstacles with free angles.

Although us layout guys think it looks messy

Looking close up, there are often little jagged edges along the lines too.

 

[loosemoose]

the angle shouldn't be smaller than 90 degrees. you can create acid traps in the manufacturing process.

 

[cyberrat]

AFAIK Acid traps are essentially a thing of the past, modern board manufacturing methods do not suffer from them as much as when boards were dipped in etchant.