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Author Topic: How do you bend a circuit board into a 1cm diameter cylinder?  (Read 7220 times)
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Dubuque, Iowa, USA
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Take a look at these pen kits and explain to me how they manage to bend them into a tight cylinder like they do. The board is wrapped around a brass cylinder and encased in acrylic.

http://www.beartoothwoods.com/catalog/index.php?cPath=21_70

Best I can guess is that they're using some special type of PCB material. I would assume that the boards themselves are production rejects because they have a number of components still attached. Although that doesn't explain why they would be available in a variety of colors.
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I wonder if I can run my servos off them.  A pen that gets up and runs away!  That's fantastic.

And they are pricey..  I still want one though..

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//LiNK

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Here's how:

http://en.wikipedia.org/wiki/Flexible_electronics
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There are three possibilities depending on the material... the one mentioned by @cr0sh (made to bend), heat, or solvent.

For example FR-4 is apparently woven glass fiber and epoxy.  According to one source "methylene chloride based paint stripper", "lacquer thinner", and heat will all soften epoxy.

Heat is probably the most difficult to get correct.  A bit too warm and you'll need a fire extinguisher.  Not warm enough and the board will break.
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Friend of mine machines pens from (among other things) the blanks shown on that site. He's an avid outdoor guy too, so always picking up lumps of interesting wood. He's made some awesome pens....
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Dubuque, Iowa, USA
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For example FR-4 is apparently woven glass fiber and epoxy.  According to one source "methylene chloride based paint stripper", "lacquer thinner", and heat will all soften epoxy.

I tried the heat thing -- it doesn't work. I clamped a board into my vise and hung a locking pliers on it to bend it but my 1500W heat gun didn't even start to do anything. Sprang right back into flat after it cooled off. Also worth noting that heat would knock off any of the SMD parts on the board.

I'll try a few solvents tomorrow. Probably a flexible thing like cr0sh described but I'm still curious.
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You can buy (standard fiberglass) PCB material in thicknesses down to about 5mil, which is easily bendable. (http://www.goldmine-elec-products.com/prodinfo.asp?number=G17455 )
Also there are alternative materials (teflon-based for fancy RF circuits, usually) that are flexible even when thick.
And then there's the kapton based material used in "flex circuits."

Getting an existing board to be flexible would be a pretty significant challenge, though.
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Itead now sells customizable FCBs, http://imall.iteadstudio.com/open-pcb/pcb-prototyping.html
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//LiNK

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