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I have some trouble about the design of my homemade double sided pcb shield. I'm not an electronic engineering, i'm just an hobbyist. In my shield i have a 9V power input and from that, using two separate circuits (with two voltage regulator), i split the 9V input power in two power line, respectively in 5V and 3.3V for supplies three IC components present on my shield. I have designed my shield using the bottom side for the ground plane and the top side for routing all track, splitting the top side into three separate areas where i placed three separate power plane. One power plane is for the input voltage and the two voltage regulator circuits. The other two areas are for the 5V circuit and for the 3.3V circuit. Is correct to design the top plane into three separate power plane as I did? I attach two images to better explain what i did.

top side button side

Update

this is my new layout, is not definitive, but is a good start! ;)enter image description here

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    \$\begingroup\$ It's not wrong. If the 5V rail has significant power consumption, I'd be worried by the narrow neck near that 4-pin connector though, which you can easily improve. \$\endgroup\$
    – user16324
    Commented Jul 22, 2018 at 11:57
  • \$\begingroup\$ No, the 5V track hasn't a significant power consumption. The current in this area is in the order of the milliampere. The board components are an INA126, an REF5030 and an ACS712. The 5V area is for the REF5030 and the ACS712 (upper and left side of the shield). The 3.3V area is for the INA126 and the input and output filters. Maybe is a problem the circuit with the ACS712. In this circuit, i'm expect a current in the order of 6, max 10A for this I have done the rail in the left much bigger than the others. I hope that this is sufficient to handle the big current that circulate in this rails. \$\endgroup\$
    – Luca80
    Commented Jul 22, 2018 at 12:17

1 Answer 1

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It is always a good idea to separate parts of the circuit with different supply voltages into different areas on PCB. While pretty much mandatory for high voltages and optically isolated circuits it is less common for small voltages and slapdash DIY projects.

In your case I'd prefer more defined areas and no 5V surrounding 3V. But your PCB is quite densely populated, so I understand why the layout looks like that.

UPDATE

I just realized that ACS712 is current sensor. I would recommend changing the power lines on the left:

  • Remove those tiny vias. Keep the traces on one side.
  • You can move all through-hole connectors (including those in other areas) to the ground side. This will simplify soldering.
  • If you do not want to move connectors then make transition to ground layer directly at the connector holes. If you do not have good plating on those holes you can add large pads around them stitched with several vias.
  • Shorten the traces. Ideally current sensor would be inserted into one wire only, the other is left off the board. But if you want both terminated at least put connectors close and with pass-trough pins facing each other, for shortest possible trace.

enter image description here

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    \$\begingroup\$ @luca80 Can you take entire 3V area plus that 5V part on top and rotate it 180 degrees? Then you'd have 3V on top, 5V at the bottom and 9V on the right, for clean separation lines. \$\endgroup\$
    – Maple
    Commented Jul 22, 2018 at 19:01
  • \$\begingroup\$ Yes i can, but in any case the 5V area surround the 3.3V area because there is the circuit in the left. However i try to organize the layout in a better way so i can separate the areas in a clean way. \$\endgroup\$
    – Luca80
    Commented Jul 23, 2018 at 9:15
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    \$\begingroup\$ As I said, you already did much better job than I've seen in many hobby projects. Just straighten separation lines a little. I also updated the answer re: area on the left. \$\endgroup\$
    – Maple
    Commented Jul 23, 2018 at 10:28
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    \$\begingroup\$ I did not suggest putting tracks on the ground side! Quite the opposite - I suggested putting through-hole connectors on the ground side, so that their tracks would remain on SMD side for easy soldering. I added that picture only in case you want to keep connectors on SMD side. Otherwise those big pads with vias are not necessary, you can use the same pads shape you had before. \$\endgroup\$
    – Maple
    Commented Jul 23, 2018 at 18:06
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    \$\begingroup\$ If the connectors on the ground side, their through-hole pins are on red side, of course. Your new layout looks very clean. Also, it is a good idea to always add mounting holes on the corners, even if you are not planning to use them. Just in case. \$\endgroup\$
    – Maple
    Commented Jul 24, 2018 at 16:43

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