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I am designing SIM900 circuit in Eagle. To test the circuit I saved the board layout in pdf and took its print out. I placed the SIM900 IC on the paper and found out that few pins do not match. I was thinking of using PCB toner transfer method to print the circuit on copper clad and solder the pins of IC manually. But few pins do not match. While placing the SIM900 on the paper, the routing goes from in between the IC.

Is there something which I am doing wrong.?

Also I want to know that when I run the DRC check, it shows clearance error for all the pins of the SIM900.

Below is the board layout

enter image description here

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The Eagle part you are using is badly designed. The pins are too wide and not centered correctly, and it doesn't have the required routing keep out areas.

For the correct dimensions, refer to the SIM900 Hardware Design datasheet figure 38: "recommended PCB decal". The pads should be 1.6mm long and 0.6mm wide, placed 12mm from the center of the part. Rectangles should be placed in in the tRestrict layer from (-7.3, -2.8) to (-1.7, 2.8) and (-1.5, 7.0) to (0.5, 9.0), to keep these areas clear.

To edit the footprint you must open the sim900 library and edit the package. Group select each row of pins and move them 12mm from center. Use the 'Change' command to make the pads 1.6 x 0.6mm and 100% round. View pad properties to make sure the dimensions and positions are correct.

The corrected package should look like this:-

enter image description here

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  • \$\begingroup\$ Thankyou for this information. Can you please share the library of the corrected package. \$\endgroup\$ – S Andrew Jul 16 '16 at 8:59
  • \$\begingroup\$ Can't post files here. Now is a good time to learn how to do it yourself! learn.adafruit.com/… \$\endgroup\$ – Bruce Abbott Jul 16 '16 at 16:33
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This is the common problem while taking print out of your design. You have to choose actual size option, instead of fit to size option while taking print out.

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