Homebrew PCBs

On 27 Jul 2014 17:01:43 -0700, you wrote:

>I was wondering how many of you folks use fillets in your PCB patterns where two traces, or any two edges for that matter, meet at 90 degrees. 

I almost always bevel at 45 degrees.  I rather wish that Eagle had a
"constrain to 45 degrees by moving both ends" behavior as an option.
> 
>I was looking at some commercially produced patterns and they seem to frequently employ fillets.  This is I presume to prevent cutting in of the pattern at 90 degree corners when the board is etched.  For a pattern produced on a computer it's easy enough to add them in.  Would it make any difference if one is using the toner transfer method?
>

I was told many years ago that traces had a tendency to break if they
were at 90 degrees (that was the expression they used).  In theory, I
can imagine that etching through at the 90 degree junction may be a
problem.  As such, I will avoid 90 degree joints (even T joints) and
bevel at 45 degrees.  

I suspect that it was a result of etching (and etching *in* at the 90
degrees inside point), since they used photoetching (KPR) and had
production etching capability in house.

Therefore, the toner transfer method would not make a difference, one
way or another.

(or so says logic and my memory).

Harvey

>Thanks in advance for your comments.
>
>John