5 Replies Latest reply: Jan 8, 2013 9:54 AM by tipo1000 RSS

Question about thermal relief (spoke) widths

tipo1000

I noticed that thermal relief (spoke) widths are same for 0805 and 0603, about 20 mils.

For SOD-323 they are about 11 mils.

The width of GND polygon where they connect is 10 mils.

 

Is that how it is supposed to be? How Eagle decides that?

 

Thanks.

  • 1. Re: Question about thermal relief (spoke) widths
    000Plasma000

    I'm not too sure about this, but I think you can change these in the DRC window. Does it really matter for your application though? For things like 0603 resistors and caps, it doesn't make much of a difference, but with DC power jacks, I've noticed that the default width generated is too thick, and I have trouble soldering the ground pins on.

  • 2. Re: Question about thermal relief (spoke) widths

    Mark Perry wrote:

    I noticed that thermal relief (spoke) widths are same for 0805 and

    0603, about 20 mils. For SOD-323 they are about 11 mils.

    The width of GND polygon where they connect is 10 mils.

     

    Is that how it is supposed to be? How Eagle decides that?

     

    Thanks.

     

    Search for "Thermals" in the manual.

     

    In essence the spoke width is 25% of the drill diameter of the pad. but

    between 1 and 2 wire widths of the polygon.

    For a SMD I believe I read somewhere that it is based on the smallest side

    of the SMD.

     

    Warren

     

     

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    Viewed / responded via the newsgroup at

    news.cadsoft.de

     

     

     

  • 3. Re: Question about thermal relief (spoke) widths

    On 1/7/2013 4:40 AM, Rahul Swaminathan wrote:

    I'm not too sure about this, but I think you can change these in the DRC window. Does it really matter for your application though? For things like 0603 resistors and caps, it doesn't make much of a difference, but with DC power jacks, I've noticed that the default width generated is too thick, and I have trouble soldering the ground pins on.

     

     

    Hi Guys,

     

    The thickness of the thermal relief spokes is determined by the width of

    the polygon. So if your polygon width is set to 10 mils your spoke

    traces will have a width of 10 mils.

     

    hth,

    Jorge Garcia

    Cadsoft Computer

     

  • 4. Re: Question about thermal relief (spoke) widths

    Warren Brayshaw wrote:

    Mark Perry wrote:

    >> I noticed that thermal relief (spoke) widths are same for 0805 and

    >> 0603, about 20 mils. For SOD-323 they are about 11 mils.

    >> The width of GND polygon where they connect is 10 mils.

    >>

    >> Is that how it is supposed to be? How Eagle decides that?

    >>

    >> Thanks.

     

    Search for "Thermals" in the manual.

     

    In essence the spoke width is 25% of the drill diameter of the pad.

    but between 1 and 2 wire widths of the polygon.

    For a SMD I believe I read somewhere that it is based on the smallest

    side of the SMD.

     

    Apologies, an error previously

    Spoke width is 50% of the pad drill diameter or the smallest side of SMD

    with a minimum width of 1 polygon wire width and a maximum of 2 wire widths.

     

    Warren

     

    --

    Viewed / responded via the newsgroup at

    news.cadsoft.de

     

     

     

  • 5. Re: Question about thermal relief (spoke) w idths
    tipo1000

    Yes, that makes sense.

     

    Thanks!

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