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Old Sep 16, 2012, 10:39 AM
The Engineer
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Creating own PCB for power connection

Have search through the net for something good up to 200A meant for multi-rotors but nothing fantastic.
So I googled How To Etch PCB and some idea came through.

But I originally wanted to do this but like to hear your thoughts.

I bought a piece of copper sheet about 300x300mm and 0.1mm or slightly more thick.
The Cu will be glued onto another piece of fiberglass sheet via double sided tape first. Then after planning the routes, I will print it out of paper and latex glue it onto the Cu and use a strong pen-knife to slice and cut through. This way I will have a nice route without misalignment.

I'm having trouble finding 0.5mm or even 1mm thick fiberglass sheet. HK has it on clothes still, untreated. So I thought maybe I can have it laid on Acrylic sheet of any color I like! And with that, I can see through from underside.. Cool..

So the next step I will cover all the drill holes with hole punched label sticker as temporary cover. Then I will lay over the Cu and base plate with epoxy mix and before it harden, will remove those round stickers with a sharp pincer.

Follow by drills and vertical connectors soldering.
Then replace all cable portion of electronics with mating connectors directly so that I can just plug say ESC like a modular sub module..

If slicing the Cu is difficult to control in order to get nice cut, can I go the chemical way:
Glue the Cu with epoxy mix, wait dry, dip into etchant after covering the routes? Will that 0.1mm be too thick to be removed by the chemical?
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Last edited by prodriverex; Sep 16, 2012 at 10:44 AM.
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Old Sep 16, 2012, 12:48 PM
An itch?. Scratch build.
eflightray's Avatar
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You intend putting around 200A through 0.1mm copper, (4 thousands of an inch) ?

I hope it's a very wide piece of copper.
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Old Sep 16, 2012, 06:00 PM
The Engineer
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I have foot print of 100x100mm to play with. Much larger than any in the market.
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Old Sep 16, 2012, 10:28 PM
The Engineer
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And that's already thicker than 1oz or even 2oz copper.
1oz of copper rolled out to 1 square foot yields 1.4mils or 0.03556mm thickness.

I just measured the copper sheet in my hand, 0.15mm. That's about 5.9mils.

My average track width is 5mm minimum, ie. 0.19685".
As a guide to Mil Std 275E - Trace Current Carrying
Capacity of Copper, http://www.armisteadtechnologies.com/trace.shtml
every 1/2oz under 0.2" can carry 7.5A.
I have 5.9mils, so that makes it 63A.

Correction to 200A: Thats the combined ESC max capacity if it is even utilized. Each can max at 55A. But my motor is rated 30A only. Multiply that by 4 of them..

I hope I'm right. All is well..
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Old Sep 17, 2012, 10:33 AM
Jack
USA, ME, Ellsworth
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Here is a winding terminator I bought from Strong Motors on a 8mm bearing tube. The three holes have typical PCB traces, just a simple circle around the hole.

I put the winding ends through the hole and take a round turn around the edge of the terminator to keep the wire in place, Then I stick the tinned end of a stranded wire in the hole. When the two wires are soldered the pad localizes the solder, the two wire ends are in contact and surrounded by the solder joint, and the setup will not be subject to vibration breakage or pulling strains. And it can handle the full amount of current that the motor will draw without overheating.

That is a 10A continuous motor, wound with a single strand of 26 AWG, the stranded conductor for the motor to ESC lead is fine stranded silicone sheathed 20 AWG wire, and I can run the motor to an overload that will burn the motor up without melting a solder joint.

Make something like that and upsize it to handle the wires you are using.

Jack
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Old Sep 17, 2012, 10:54 PM
The Engineer
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Thanks Jack..

I'm building quad now. I wish if there's a way to transfer power with a strong PCB to and from the boom to ESC.. Maybe wire 3 copper strip on the surface of the square rod!

Here's my design for the electrical board for direct ESC mount..



The 3phase cable will come out from the end of the boom, to the centre of the base plate, goes up and connect to bullet connectors directly soldered to the bottom track of the electrical board.

Some peep will believe in direct soldering onto board.

I'm working on modular solution with maintenability in mind. With a balanced prop and good shaft, vibration is minimum and thus we should trust these bullet connectors.. not those usual type. I'm a fan of Zero Loss bullet connectors..
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Old Sep 20, 2012, 08:09 AM
The Engineer
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Now that the frame and motor mount and motor is done.. time to move up the base and think of how to mount the ESC.

My design believe in having a low CG and all components should concentrate to the middle as much as possible. Even my base plate is very small at 100x100mm for a 750mm Quad.

So to reduce wire and cable clutter, I want to formulate my own PCB to carry those power.

So the idea came from http://hackaday.com/2008/07/28/how-t...gle-sided-pcb/

Its interesting to learn that one can laser print onto practically any flat surface, literally.. But instead of meddling with pungent chemicals, i decided to adopt my own method..

Here's the PCb plan on drawing:


S that means, we can employ the same manner to transfer these lines onto a sheet of copper! Voila!

But which paper or foil to use? I suppose using the aluminum foil looks better as I can see how the print out will turn out.. But before I can do that, I think it may sense to reverse the color like this:


Reason is simple. the track should be clear of any printing so we do not need to clean it off later. The portion to be cut away will be printed instead.

Then off to print direct onto the aluminum foil.. I tried out both dull surface and shiny surface, the effect is the same..



Now cut away those tape that held the foil to the paper and remove slowly taking care not to crisp the foil. I realise to print it very nice, always use a super nice and flat foil without any lines.. try.. The foil i had in hand was a lousy one, it was thinner than usual..

Now slowly flip it over and lay the foil with the printed side, down to the copper sheet. You can see the print did almost an embossing on the foil.. this is before ironing..


Tips. Now, you gonna move that iron around so better tape down the foil too. But do not use plastic tape. I happen to have aluminum film tape so it came in useful..

Then I place the sheet on a flat surface like an acrylic sheet top with a thick but firm cardboard.. I lay a smooth cloth like a shirt over it so that my iron can slide smoothly..


Turn the iron to the hottest and lets do it!


After 3-4 minutes of moving the iron around making sure it covers all the area..
Remove the hot iron.. remember to turn it off.. wait for the copper sheet to cool.. you can put it in front of a running fan to cool it faster..

And once cool enough to work on, peel the foil away slowly.
Here's are the results:
This is with less than idea flat foil without lines..


This is from a nicer foil, almost perfect without lines.


You can see the importance..

I will cut the bull short, than i just trim the printed portion with a big strong pen knife.. And here's the result:


The above is abstract on the work on the electrical connection solution.

Full built progress updated progressively here:
http://www.rcgroups.com/forums/showthread.php?t=1732257
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Last edited by prodriverex; Sep 21, 2012 at 10:32 AM.
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Old Sep 21, 2012, 10:41 AM
The Engineer
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The coolest PCB form!

Have you seen such PCB before?

PCB on clear acrylic..



On the other clear side of PCB.. nice for now. gonna add quad ESC's 3-phase track. So it's a dual layer!
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Old Sep 22, 2012, 11:15 AM
The Engineer
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More updates here: http://www.rcgroups.com/forums/showp...2&postcount=15

http://www.rcgroups.com/forums/showp...8&postcount=16
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Old Sep 29, 2012, 02:49 AM
The Engineer
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The Power track project is completed! Simply push and snap the ESCs in place!

Heres the update..
http://www.rcgroups.com/forums/showt...1732257&page=2

Here is a pic of it:


As prototype, this weigh about 120 gm with all the connectors. I hope the next version should be done with actual PCB fabrication with BEC 5V too. That will weight 4x less maybe..

The dimension is 114x114mm
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Last edited by prodriverex; Sep 29, 2012 at 02:58 AM.
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