The last batch of SDU boards that I ordered was unusable because the 5V rail was shorted out. I couldn't find any other explanation then swapped inner layers. By design layer 2 is 5V, layer 3 is GND.
Now, after staring at the gerbers I'm starting to think it must be something else. Vias go all the way through and if a layer is etched away around the via it doesn't make contact, if it isn't etched, it does make contact. Shouldn't matter where the layer is in vertical order or am I missing something?
Here's the GND layer (layer 3) recognizable by the connection to the wifi modules thermal pad
And here the 5V layer NOT connected to the thermal pad
I have ordered a batch of 5 boards of that same design before and they worked normally.
Inner layer sequence [SOLVED]
- johu
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Inner layer sequence
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- johu
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Re: Inner layer sequence [SOLVED]
Yes, of course it was something else! The diode of the 5V buck converter was placed in wrong polarity. Spun it and board works
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