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Arbitary SMD and DRC frustration

Former Member

I have created a footprint for a SON-6 package, quite small.  The datasheet calls for oblong pads 0.28mm wide by 0.75mm long and one end being completely rounded (i.e, r=0.14). I used a polygon with wire width 0 to achieve this as the embedded help file appears to say DRC does not check wire width of polygons used for arbitary pads.  However, DRC is throwing up a width error for these smd pads.  If I thicken the wire width to fit in with my DRC settings I can't create the smd shape I need. Is this a bug in the software or a bug with the way I'm trying to work?  Any feedback other than 'just use rectangular smd pads' is welcome.

 

Thanks, William

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  • 0 in reply to Former Member

    Hi William,

     

    you have to draw the polygons in a reasonable wire width. If you take 0 as width, there will be additional constraints for the production process. Gerber data usually doesn't accept 0 width data. This is also written in the manual:

     

    8.14 Arbitrary Pad Shapes

    [.........]

    The typical way to draw an arbitrary pads shape is:

    * Place a PAD or SMD

    * Use POLYGON to draw the final pad shape

    For a SMD typically in Layer Top

    For a PAD you have to draw the final shape in all the layers you plan

    to use (Top, Bottom, Inner layers...)

    The PAD/SMDs center must be inside the polygon's area. Otherwise

    that polygon is not recognized as a part to the pad. Use a reasonable 

    wire width for the polygon, which fulfils the Design Rules.

    [........]

     

    I am currently discussing with our development team whether we can change

    this for the future.....

     

    Regards,

    Richard

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