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SMT problem

Abdelaziz

I design a PCB using eagle software in my design i use SMT microcontroller atmega2560 after finishing the design I print it in paper but I found that all controller pins are shorted together however in the design there is no short between controller pins?

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  • 0 in reply to Abdelaziz

    Hi,

    it seems you have some mistakes with the polygon and with the b'stop, t'stop layers as well.

    Also, please reroute the 5V track and the reset track. -> 5V can be a wire_bridge on the left side of the µC also on the right side.

    Then the GND can go direct under the modules. The reset as well can go as a wire_bridge on the right side of the µC so this don't go around the board.

    So then you can eliminate the GND wire-bridges. Place the modules closer to the µC.

    GND wire_bridges are very bad (ringing, bouncing, etc..), better are signal- or and supply- wire_bridges.

    The bypass_caps must be placed so close as you can to the active components.

    And you can rotate they so that the wire tracks are going straight.

    Tipp: try rotating the µC 45 deg. than the tracks would going going better. And the PCB can be a bit smaller, so small as possible.

    Avoid <=90deg tracks and outgoings in the middle of the track.

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  • 0 in reply to Abdelaziz

    Hi,

    it seems you have some mistakes with the polygon and with the b'stop, t'stop layers as well.

    Also, please reroute the 5V track and the reset track. -> 5V can be a wire_bridge on the left side of the µC also on the right side.

    Then the GND can go direct under the modules. The reset as well can go as a wire_bridge on the right side of the µC so this don't go around the board.

    So then you can eliminate the GND wire-bridges. Place the modules closer to the µC.

    GND wire_bridges are very bad (ringing, bouncing, etc..), better are signal- or and supply- wire_bridges.

    The bypass_caps must be placed so close as you can to the active components.

    And you can rotate they so that the wire tracks are going straight.

    Tipp: try rotating the µC 45 deg. than the tracks would going going better. And the PCB can be a bit smaller, so small as possible.

    Avoid <=90deg tracks and outgoings in the middle of the track.

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