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Two trace widths on the same net

firatkocak

Hi,

 

I am designing a simple development board for myself. The mcu is

Pic18F8722 and because of its pin pitch limitation, i have to use 8 mil

for trace width. For i/o signals it is ok but i want power lines to be

at least 10 mil. Is it possible to tell the auto router to shift 8 mil

before entering mcu pins ? If it is not possible with auto router , what

would you advise to accomplish this ?

 

Best regards,

 

Firat Kocak

 

Parents

  • i don't think the difference between 8 and 10mil is worth worrying

    about, but i would make power connections as fat as possible :-). and

    yes, at least in v4 of EAGLE it is easy to make the trace widths change

    anywhere you want. you just use the CHANGE:WIDTH function and you can

    manually make any segment of any net whatever width you want.

     

    to do it automatically, make a "class" for the nets you want to be

    different sizes and assign a width to that class and then change the

    class for all the nets for which you want the wide width.

     

    most people route power connections by hand first along with any

    critical nets that need to be in specific places and then let the

    autorouter clean up the rest. if you do this, you may find that it's not

    even worth making a class for the power nets, you just set their size as

    you route them.

     

Reply

  • i don't think the difference between 8 and 10mil is worth worrying

    about, but i would make power connections as fat as possible :-). and

    yes, at least in v4 of EAGLE it is easy to make the trace widths change

    anywhere you want. you just use the CHANGE:WIDTH function and you can

    manually make any segment of any net whatever width you want.

     

    to do it automatically, make a "class" for the nets you want to be

    different sizes and assign a width to that class and then change the

    class for all the nets for which you want the wide width.

     

    most people route power connections by hand first along with any

    critical nets that need to be in specific places and then let the

    autorouter clean up the rest. if you do this, you may find that it's not

    even worth making a class for the power nets, you just set their size as

    you route them.

     

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