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I prepared a PCB layout on Eagle Cad 6.4

enter image description here

Here below is the end version of the PCB

enter image description here

As you can see the the layout is printed as the MCU will be placed from the bottom layer. However, I would like to place the MCU on the top layer and solder the legs on the bottom layer. Could anyone explain me what do I need the change on the layout so that the MCU could be placed on the top layer and foot print of its leg would be on the correct orientation on the bottom layer?

EDIT: The layout that was printed on the paper enter image description here

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4 Answers 4

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In Eagle, just place the component on the top layer, not the bottom. Since it is a through-hole part, Eagle should allow you to route from the opposite layer. You will need to double check the print settings so that the vias line up on both layers (possibly using the 'Mirror' print option in Oceanic815's answer).

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  • \$\begingroup\$ If I place the component on the top layer, then the foot-print of the component will be on the top layer as well, right? I am etch the board myself, it would be a lot easier if all traces are on a single layer. Is there a way to place the foot-print of the component on the bottom layer but expects to place the component from the top layer? \$\endgroup\$
    – sven
    Jun 20, 2013 at 19:33
  • \$\begingroup\$ The metal of the vias should be on both the top and the bottom. Are the vias only printing on one side? \$\endgroup\$
    – Justin
    Jun 20, 2013 at 19:44
  • \$\begingroup\$ I take print out of only one page as the connections are on a single layer. \$\endgroup\$
    – sven
    Jun 20, 2013 at 19:58
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From what I see I think that your PCB is homemade. When you print the layout you need to consider that in these cases you need to print the PCB mirrored. With Eagle you can do that selecting the Mirror option in the print menu.

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  • \$\begingroup\$ yes it is a home-made PCB and it is my first try. I printed the layout by selecting mirror, black, solid. \$\endgroup\$
    – sven
    Jun 20, 2013 at 19:29
  • \$\begingroup\$ So the PCB of the photo was printed in Mirror mode? \$\endgroup\$
    – Oceanic815
    Jun 20, 2013 at 19:46
  • \$\begingroup\$ I attached a new photo that shows how the layout is printed on the paper. it seems mirrored there. should I have not mirrored the print out? \$\endgroup\$
    – sven
    Jun 20, 2013 at 19:54
  • \$\begingroup\$ How did you do your PCB? If the layout printed on the paper is the layout the you used in order to made your PCB I think you have mirrored the PCB two times during it's costruction, with the result that it was not mirrored. \$\endgroup\$
    – Oceanic815
    Jun 20, 2013 at 19:59
  • \$\begingroup\$ After printing out, I used iron to transfer the toner, then used an acid to etch the board. I followed the instruction on wikihow.com/Create-Printed-Circuit-Boards \$\endgroup\$
    – sven
    Jun 20, 2013 at 20:08
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Try printing the image without mirroring it. If you think of it in your head, when you apply it to the board, it essentially gets mirrored. By mirroring it, then applying it, technically you are mirroring the image twice.

When i etch boards for myself, the last check that i do is print the image, then flip the paper over so i'm looking at the back. Hold it up to the light and what you see, is what you will see once the ink has been transferred to the board.

Alternatively, you can print a mirrored copy to see what the board will look like instead of holding the paper to the light, but remember to apply the non-mirrored copy.

Edit: This only applies to the iron application method, if you were to use a photoresist with a clear print, you should print it mirrored.

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The convention in the CAD programs I've used is that you are looking at the component side of the board in the program whild doing the layout. You can use your X-ray vision to look through the board and see the traces on the solder side.

Pads for through-hole components should normally appear on both the component and solder sides.

Bear in mind that the CAD systems are designed with the expectation that the board will be manufatured commercially, with copper on both sides, and plated-through holes. When making single-sided boards at home, you will have to make provision in your design procedure to allow for single-sided copper, and no through-hole plating. You should place all your tracks on the "solder side" layer in the program, and, as others have said, you may have to mirror the image when you print it.

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