new to eagle

Discussion in 'The Projects Forum' started by katos, Feb 12, 2015.

  1. katos

    Thread Starter New Member

    Jul 9, 2014
    2
    0
    Hello,

    I have started learing eagle software. I have created board but i m not sure if have done everything the right way.

    My question is especially about led element that was't available in library and i had to created it on my own. Could anyone look at it and tell me if i made it right way. I'm mostlly unsure about middle part, where heat should be absorbed.

    Anyway i upload my schemat and library to attachments so if anyone could help i would be really glad.
    Because i can't add .rar nor .brd files i upload schema here :
    https://www.dropbox.com/s/g4v7tw3kfuk31o9/led_board.rar?dl=0
     
  2. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
    5,671
    897
    EDIT: My assumptions about the pads and heat sink, which were based on your device, appear to have been wrong based on the datasheet.

    Please attach a link to the full datasheet.

    John



    On your board, if you run DRC you will see a problem:
    upload_2015-2-12_10-53-31.png

    You apparently have a polygon that covers two pads (P$5 and P$6):
    upload_2015-2-12_10-56-15.png

    You have made a good start for your first Eagle board.

    I didn't take the time to review the datasheet carefully, but I assume the center area is a heat sink. You also appear to have used wire to make the two pads (named + and -). Apparently Eagle accepted that, but it is not accepting the polygon covering two different pads.
    1) I suggest using a pad to create the two pads you need. Yon can define pad side in the little box at the top that appears when you click on the tool. That way, you are sure to get all the required layers.
    2) For the center, you can have two pads for the same signal, but I don't think that is what you want to do. I suspect you want that to be a heat sink area.
    3) If you want bare copper there, you can outline the polygon with t-stop (29) or t-place (21), which will prevent the solder mask from being put over that area.

    If I get a chance, I will look at the datasheet and make you a device.

    John
     
    Last edited: Feb 12, 2015
  3. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
    5,671
    897
    Actually, the recommended board layout is a bit more complex than you show. The center bar is, in fact, part of the recommended heat sink. The overall size is not shown, but I estimate it is about 5mmX5mm. Attached is a zipped folder with the dxf file. I use Ashlar-Vellum Graphite for 2D CAD, and its exports to dxf are accurate, but they can look a little funny.

    Is this going to be a homemade board or commercial? If the latter, do you intend to get them commercially made, i.e., do you need the stencil pattern too?

    EDIT: Here's a png that you can open

    John
     
    Last edited: Feb 12, 2015
  4. katos

    Thread Starter New Member

    Jul 9, 2014
    2
    0
    It is going to be mcpcb made commercially, so i will need stencil pattern. I want leds to have good heat sink.
    So which ones of those i need to change in library.

    In atachment are all datasheets of leds.
     
  5. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
    5,671
    897
    Your library doesn't follow the recommended copper pattern. It follows the pads on the underside of the device. Those are two separate things. The information you need is on page 13 of the datasheet. I estimated some of the dimensions, because I didn't have your board to go on. It is implied that the larger the copper heat sink, the better. You have to integrate the three parts: 1) copper, 2) solder resist, and 3) stencil. That is one reason to use the Eagle "pad" rather than try to make your own.

    John

    Edit: With mcpcb, I think you could probably change the pad arrangement from that shown in the datasheet as they depend on surface conduction of heat. I have no experience in designing for metal core. Perhaps the manufacturer you plan to use has some advice or may even have the library you need.
     
    Last edited: Feb 13, 2015
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