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component dimensions

Discussion in 'CAD' started by sycochkn, Jan 19, 2008.

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  1. sycochkn

    sycochkn Guest

    Are the EIA/JDEC dimensional specifications more complete than what is found
    in the usual manufacturers data base? I know the manufacturers specs are
    usually quite adequate for board layout but I am making solid models of
    components that I deal with and would not like them to look funny.

    Bob
     
  2. Many manufacturers will also reference the relevant EIA/JEDEC
    specification. If they do reference it, then they should conform to
    the specified specification.
    Also look at http://www.ipc.org/ContentPage.aspx?Pageid=4.6
    There are also a few companies that sell 3D models for electronic
    components.

    Regards
    Anton Erasmus
     
  3. sycochkn

    sycochkn Guest

    I do not have an issue with models, just how they are defined dimensionally.

    http://home.earthlink.net/~sycochkn1/SimpleBalancedReceiver.pdf

    Bob
     
  4. sycochkn

    sycochkn Guest

    That was done with AutoCAD 2005. I am intending to make an AutoCAD drawing
    with blocks containing the solids, pad stacks, silkscreen etc. I intend to
    use polylines for traces. after I generate my Gerber and Excellon files from
    the DXF I intend to convert from Gerber and Excellon back to DXF and insert
    the computer generated file back into AutoCad to generate the solid version
    of the etched layers and vias.

    Bob
     
  5. Hi, Bob:-

    How are you converting between DXF and the Gerber & Excellon files?
     
  6. sycochkn

    sycochkn Guest

    I am rewriting my old program. I should probably try the old one and modify
    it.

    Bob
     
  7. What I do is model all my components up with the SMT or TH pads attached.
    After placing the component models, I then apply a .gif of the silkscreen
    and traces to the surface of the board. Looks very nice fully rendered, and
    keeps the file sizes under control. I've done some samples of manually
    created models of the traces, and I think applying a graphic of them and the
    silkscreen looks more realistic. Once I have a real board in hand, I can
    flatbed scan it and apply the graphic of the real thing. Also, having the
    pads modeled lets me apply a metallic surface to that part of the model, as
    they are not covered by soldermask. I use IronCAD which does a nice job with
    photorealistic rendering. Not familiar with how AutoCAD 2005 works for
    this...

    I've also looked for quite some time for a method of converting the gerber
    data to .dxf or preferably .sat or some other 3D format (adding a slight
    extrusion to the traces) but have not had much success in finding anything.
    Protel99se has a "board in 3D" feature, but cannot export the file. Newer
    versions of the Altium software can export, but I'm not upgrading just to
    get that feature. This would be faster than working with the graphic images
    for quick stuff though.

    Chris
     
  8. sycochkn

    sycochkn Guest

    Flashes are blocks. The aperture name is defined by the block name. The
    aperture definition is defined by the name of a block nested in the aperture
    name block. The location of the flash is defined by the insertion point of
    the block What appears in your drawing is arbitrary.
    Traces are polylines. The aperture definition is determined by the width of
    the polyline. The start and end points of the traces is determined by the
    vertices of the polyline. The name of the gerber file is defined by the
    layer name. for gerber RS274D the apertures are defined in a seperate file.
    for RS274X the apertures are defined in the gerber file and rest of the
    header information is entered manually. The Excellon file is defined in a
    similar manner.

    Component definitions are done manually using blocks made with the aperture
    blocks. When you insert a component The component model, the top assy, the
    silkscreen, the solder mask, the pad stack etcb all come with it. What ever
    is left over is done manually.

    Bob
     
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