routing angle 45 or 90? what is differance and what is better?

[ec_nisarg]

seems to be a dumb question... but can any one tell me that......

why it is suggested to route any track at 45 degree angle rather than to route making an 90 degree angle...

what are pros of routing at 45 degree...???

 

[Mattylad]

Well, if you read articles like this you would think that there is nothing wrong with a 90 degree corner. For an electronic engineer there is not also because they know nowt

There is a big "it depends" in the answer, because it depends if your talking about low signals stuff, high speed or RF as each can have different requirements for track design.

However if you are a PCB engineer we treat the board like an artwork, as well as making the board work we also like to make it neat, pretty etc. 45 degree corners do this as long as they are not affecting circuit performance.

 

[loosemoose]

a 45 degree is shorter than a 90 degree.

 

[Mattylad]

Taken from here read the first one and laugh.


https://www.ultracad.com/articles/flying.htm
https://www.ultracad.com/articles/90deg.pdf

 

[ec_nisarg]

were they making pcbs or mayonnaise?? ROFL....

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ok.. let me tell you that i design pcbs at my work place, my pcbs are mostly (99%) digital ones. higher frequency that can be on my board is crystal frequency (max 20MHZ). all other traces have much lesser frequency (in some KHz), and all lines have mostly 12 or 5 Vdc,...
so
i can say that i should not worry about 45 or 90 degree bands in my pcb??
correct me if i am wrong...

 

[123jack]

I'm no expert at PCB layout (I do mostly prototypes and one off's - I use eagle normally) so I expect ec_nisarg knows better than me
but if I remember correctly you would use various directions and possibly angles depending on the board layout and application
to prevent tracks becoming transmission lines and so on. Often you might layout one layer horizontal and another layer
vertical especially when working with RF on boards. There may also be an issue about sharp edges (90degree angles) becoming antenas.

I loved the links mattylad - I think I'll build an electron "cue" to pot them back in their "holes" when they fly out.

If you are unsure it is probably worth finding a good book on RF layout. It can be an issue but I'm uncertain as to the details.
I suspect up to 20Mhz you wouldnt have much of a problem though.
If it is an issue you may be working at frequencies that require something other than FR4 board too.

 

[godfreyl]

There was one good point in that article:

90 degree corners introduce excess capacitance and cause a small change in characteristic impedance.

That could be a problem with very high speed signals, as it will cause reflections.

 

[marce]

Err firstly, most traces (or routes) on digital boards are tranmission lines.
RF is a different discipline than digital, learn digital and high speed digital first, RF is not for the faint hearted and only worth learning if you are doing proper RF layout.
Tha advatages of using 45 deg corners are the layout tends to look neater.
You can fit more traces into tight spaces.
And most importantly Engineers like them, it does not matter one iota whether electricly they are a problem or not, the engineer is the design autority for a PCB so it pays to keep him.her/them happy.
Dr Howard Johnson has some papers that go into more detail on the subject.
Back in 1990 I did a 25+MHz Motorola based board where we used 90 deg corners for the prototype, as a test, no different from 45s

 

[praveenlb]

i will go with arc routing....no 45 no 90 lol..
some one prefer arc some prefer 90 some one 45. unless otherwise specified high speed you can root with 45 degree angle.

 

[sivamani]

with 90 routing, it will create impedance mismatch at corners that is why this is not prefered for critical signals and also due to sharp bends it will produce glitches when signals are running at high speed.

 

[ec_nisarg]

as i have told above.. RF is not my concern...

my boards are purely digital ones. only few lines would be analog (for amplifiers only).. so i should not concern about angles.

 

[FvM]

my boards are purely digital ones. only few lines would be analog (for amplifiers only).. so i should not concern about angles.

As far as you are designing general purpose digital and low speed analog you shouldn't particularly care about angles.

There's however a bundle of layout related features that might be interesting for your design, though:

- well considered, functional placement
- route planning
- ground net layout and bypass capacitor placement
- avoiding crosstalk
- controlling active and passive EMI

None of this points is directly related to artwork "finish". But a good layouter who is paying attention to the above list usually appreciates a good-looking layout.

 

[Mattylad]

PCB layout is an art, the gerbers were called an artwork.

We are artists and like our art to look good as well as work well.

So we make it so that traces look neat and even, that groups are routed in a regular pattern etc.

Taking pride in what we do.

Chuck a board that works together or make one that also looks neat and tidy, your choice.

 

[ec_nisarg]

can you people give me something to read, so that i can make my pcbs even batter??
i will google though, but some one can show me a good article than i would appreciate it..

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here is a screen shot of one of my pcb... please tell me if this is good or i can improve it more further,,

aslo the via right to '30' is giving me crosstalk how can i omit it..???

 

[Mattylad]

Why on earth have you got teardrops on all your SMT pads?

Thats absurd.

And if your vi is giving/getting crosstalk then move it and it's traces or move the thing thats giving/receiving the crosstalk.

 

[ec_nisarg]

Why on earth have you got teardrops on all your SMT pads?

Thats absurd.

OK NOW I THINK THAT I AM COMPLETELY NOOB,,,,,

one question... why??
why i cant put teardrops on smt pads?

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Why on earth have you got teardrops on all your SMT pads?

Thats absurd.

OK NOW I THINK THAT I AM COMPLETELY NOOB,,,,,

one question... why??
why i cant put teardrops on smt pads?

 

[babbit12]

PCB layout is an art, the gerbers were called an artwork.

We are artists and like our art to look good as well as work well.

So we make it so that traces look neat and even, that groups are routed in a regular pattern etc.

Taking pride in what we do.

Chuck a board that works together or make one that also looks neat and tidy, your choice.

Couldn't of said it better myself Mattylad !

 

[Mattylad]

cheers babbit,

ec_nisarg - why did you add them? what was you thinking about when you did?

From what I can see they are unnecessary, you have also made the pads bigger than they need to be and although they are not so prominent these days please research acid traps.
(C20/R34 junction especially)

If you wanted bigger tracks between them then use bigger track widths, currently it looks - well no offence but (given what I said above about being an artist) horrible. :wink:

But if there is good technical reason for them then they are OK... lol

 

[ec_nisarg]

cheers babbit,

ec_nisarg - why did you add them? what was you thinking about when you did?

From what I can see they are unnecessary, you have also made the pads bigger than they need to be and although they are not so prominent these days please research acid traps.
(C20/R34 junction especially)

If you wanted bigger tracks between them then use bigger track widths, currently it looks - well no offence but (given what I said above about being an artist) horrible. :wink:

But if there is good technical reason for them then they are OK... lol

there is no such technical reason...
actually i put them because we have in house production facility and many of our pcbs are hand soldered.. and workers use high watt soldering irons, (they are used to.. no way to tell them to use lower wattage irons) .. so we have to keep pads somewhat larger and i have to put tear drop so upon heating pad does not come out of pcb... for bulk we give order to professionals , who use pick and place.. and they do not have any problem with larger pads,, (some times they argue with some legends, not more than that...)

 

[marce]

Er PCB layout is an engineering discipline, its not art its engineering, especially high speed digital layout.
I can vouch for Mattylad being an artiste...:lol:
Unless you are going into the gigaHz, 90 deg corners do not add that much of an impedance mismatch, so you don't really have to worry.
As to the electrons as they only travel a few mm per hour so aren't gonna skid of the traces at the corners...