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I was thinking on creating a dual layer PCB where on one side I would put the MYRRA (45043) AC-AC PCB mount transformer, and on other side the remaining components. In other words I would have the AC tracks along with DC tracks, low DC amperage and up to 16A on some AC tracks. And at this point I started thinking:

  1. Is there any way to isolate the heat generated by the AC-AC transformer to the other side of the board?
  2. What special consideration should I take when mixing AC and DC tracks on the same PCB?
  3. There's some calculators on the net to calculate track width and so on, but I could not figure out how much heat it will be generated from transformer.
  4. Taking into consideration that same tracks could be at certain point up to 16A AC, should I consider an inner layer (for isolation purposes), instead of an external one? Is it recommendable, good practice, or is that plain old nonsense?

Any help would be gratefully appreciated. Some literature I should read and other things I should consider... please let me know...

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    \$\begingroup\$ Are you saying your electronics are going to draw 16A, or is that for the whole appliance? You don't want all that current on your board, and if your electronics are drawing 16A, that transformer isn't going to get hot, it's going to catch on fire. \$\endgroup\$ – Matt Young Aug 24 '13 at 16:04
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    \$\begingroup\$ No no... I'm saying that some of of tracks (probably just one or two) might get up to 16A. But that's not drawn from the electronic part. It will just go through the PCB since the DC part of the circuit is controlling a relay and deciding if it will power up some AC appliance at home. The transformer itself will only endure up to 1A. \$\endgroup\$ – cvicente Aug 24 '13 at 16:15
  • \$\begingroup\$ I forgot to mention, bu the trasformer is a 230VAC to 6-0-6VAC... \$\endgroup\$ – cvicente Aug 24 '13 at 16:18
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    \$\begingroup\$ I got half way thru the question and gave up. Can you get to the point quicker without all the waffle - you can waffle after getting to the point. I'm not being nasty, I'm advising that if you want a good answer, don't put folk off with your life story before getting to the question. \$\endgroup\$ – Andy aka Aug 24 '13 at 17:34
  • \$\begingroup\$ I'll take your advise under consideration... thank you. Look at the bullet numbering part of the question... \$\endgroup\$ – cvicente Aug 24 '13 at 17:46
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Fiberglass (PCB material) is not a great thermal conductor, but it is not a great thermal insulator either. The only way to thermally isolate parts is to increase the distance between them, or connect them with a material with higher thermal resistance. Generally air is a better thermal resistor than FR4.

One solution is make the pcb bigger and put the other components further away from the transformer.

Another is make a 2nd pcb and connect it to the first pcb with a connector that leaves an air gap between them. I'm suggesting this solution in case you can't expand the "footprint" of the board beyond the size of the transformer.

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  • \$\begingroup\$ Thank you Photon. In what regards the size of the PCB being the actual size of the transformer, It's actually just a start-up hypothesis, since it will depend (unfortunately) on the casing I'm able to put my hands on. On the other hand, I'm trying to go for the most compact sizing possible, so the two PCBs option with some spacing between them is actually quite interesting... \$\endgroup\$ – cvicente Aug 24 '13 at 19:06

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