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Good Practice for PCB CAD

Discussion in 'CAD' started by Brian Fairchild, Jul 28, 2003.

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  1. Hi

    I'm looking for input from other people as to how they present their
    Gerber files for manufacture.

    Specifically, what information do you put onto the layers to identify

    Do you put text inside the board or outside it? Text or numbers?

    I've seen some people use a 1,2,3,4,5... box

    Basically I'm trying to develop a standard for myself and
    subcontractor to use. Mostly 2 layer or 4 layer PTH stuff.

    Any pointer gratefully received.


    reply e-mail address doe not work. see sig.
  2. Spam Hater

    Spam Hater Guest

    I put the "boxed numbers" inside the board. Right near the edge. So
    I can check them visually when I get the boards back. Yes, I have
    gotten boards with missing layers.

    I also name the gerbers 'layer01.gbr', 'layer02.gbr', etc. Not
    compent, plane, solder, etc.

    It also helps to have plain reading text on top and bottom layers.
    Part numbers and country of origin are good things to use.

    When in doubt, be painfully obvious.

  3. Hal Murray

    Hal Murray Guest

    I'm looking for input from other people as to how they present their
    I suggest asking your board vendor what they prefer.

    You can put big text with the layer info (and version/time stamp)
    outside the board outline. The board vendor will have to throw it
    away, but it makes it easy for them to check that they are doing
    the right thing.

    If you have room, you can put "Layer <n>" on each layer, perhaps
    staggering the numbers so you can read them all if you hold it
    up to the light. (That gets tricky for plane/negative layers.)
  4. In a flurry of electrons Hal Murray spake thus:
    The problem is that my boards typically get made by three different
    companies: the people I use for fast prototypes, the people who make
    the pre-production/first run batches for the people I 'work' for and
    the final production house.

    Not ideal I know. Luckily we're not doing anything difficult.
    Good idea.
  5. Hal Murray

    Hal Murray Guest

    I suggest asking your board vendor what they prefer.
    Ask all 3 vendors - you have to do what they want/need eventually.
    If you are lucky, you can find a least-common-denominator they will
    all be happy with. If not, consider some script hacking to
    automate the conversion so you won't forget a step or fat finger
    something. That might be something as simple as renaming files.

    In the old days (5-10 years ago), there was a person involved
    with every board. They would call you if there was any confusion.
    Now, some/most of the inexpensive order-via-web board shops are
    bypassing that step. You have to do exactly what they say, but
    they will have the fine print on their web pages.
  6. Paul Burke

    Paul Burke Guest

    I find PCB-Pool particualry good in this respect- the Gerber files seem
    to be thoroughly checked, and call to sort out any ambiguities. Even
    when I MEANT to leave no hole in a pad (for a polarising pin). They have
    been in fact better than some regular manufacturers I have used in the past.

    Usual disclaimer.

    Paul Burke
  7. William Lenz

    William Lenz Guest

    Brian Fairchild:

    Our standard was:
    The Gerber Data is clean to avoid anyone needing to edit them.
    The files names were the "board number" then "_Sx.grb" the x being 1-however
    many sheets you have.
    A hard copy packet was then created and sent to the board house (faxed,
    mail, or PDF)

    Detail on the hard copy stuff
    We paced common text on a common layer. Then layer spicific text on other
    layers, you then print out the layers you want. This works well if you have
    a software package that has enough layers to do this, and can save printing
    Not that we didn't trust our board houses, but....we didn't trust them :eek:).
    We tried to supply to the board house a clean gerber file no touch up
    necessary on there part (other than to array them when needed).
    Our standard was:
    Sheet 1: Board and mfg info (Hard copy only)
    Sheet 2: Top (Hard copy with text, and clean gerber
    Sheet 3: Bottom (Hard copy with text, and clean gerber
    Sheet 4: Solder mask top (Hard copy with text, and clean gerber file)
    Sheet 5: Solder mask bot (Hard copy with text, and clean gerber file)
    Sheet 6: Solder paste top (Hard copy with text, and clean gerber file)
    Sheet 7: Solder paste bot (Hard copy with text, and clean gerber file)
    Sheet 8: Array info if applied (Hard copy only)

    Multi layer boards sheets were inserted between sheets 2 and 3 and all
    sheets incremented by 1.
    This works best if you can save all the work involved as a series of
    defaults then just recall them.

    At least an idea.

  8. In a flurry of electrons I spake thus:

    Just a quick thanks to all who made suggestions.
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