Eagle pad diameter/drill size?

Discussion in 'General Electronics Chat' started by jp1390, Aug 24, 2011.

  1. jp1390

    Thread Starter Member

    Aug 22, 2011
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    2
    Hello, I just have a quick question regarding pad size for one of my parts. I am creating a custom package for a coin cell battery and the manufacturer's drawing specifies that the pins are rectangular with dimensions of 0.2 mm X 0.75 mm.

    I went into the pad properties but wasn't sure what to select for shape, diameter, and drill size. I assumed that since the pins have a width of 0.75 +/- 0.1 mm, that the diameter of the hole should be at least 0.8 mm, but I wasn't sure about drill size.

    I am also confused at why there is an "auto" option for diameter.

    Any help with regard to this would be great!

    Cheers!
     
  2. tracecom

    AAC Fanatic!

    Apr 16, 2010
    3,869
    1,393
    By the Pythagorean Theorem, the diameter of the hole should be 0.776 mm. which is just over .030". I would make the hole .040" and the pad size .090" round. Better a little oversized than too small.

    I don't know Eagle, but my guess is that when you specify a pad size, Eagle will automatically pick a drill size.

    Coincidentally, today I created a battery holder for 20mm coin cells in DipTrace. I used .040" hole and .075" pad, but after your question, I went back and changed it to a .090" round pad.
     
    Last edited: Aug 24, 2011
    jp1390 likes this.
  3. Pencil

    Active Member

    Dec 8, 2009
    271
    38
    Quick explanation,

    The final size of the pad is set in the design rules, Restring tab, when
    value is left to "auto".
     
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  4. jp1390

    Thread Starter Member

    Aug 22, 2011
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    2
    Cool, this is my first library from scratch component haha. Sorry, when you mean hole and pad size, which refers to the drill size and diameter?
     
  5. tracecom

    AAC Fanatic!

    Apr 16, 2010
    3,869
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    Yes, when I say hole, I mean drill, and by pad, I mean the O.D. of the pad. Although technically, the hole size will be a bit smaller on a plated through hole than the drill. The plating reduces the I.D. just a little.

    You can see my battery holder here: http://forum.allaboutcircuits.com/showthread.php?t=58580
     
  6. jp1390

    Thread Starter Member

    Aug 22, 2011
    45
    2

    That's awesome! I was lucky that the package I am buying comes with PC pins, but that is really cool.
     
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