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Author Topic: Etch one's own flexible PCBs somehow?  (Read 289 times)

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Online cdev

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Etch one's own flexible PCBs somehow?
« on: November 15, 2017, 02:04:40 AM »
I would like to somehow DIY flexible PCBs using some fairly low tech/cheap method (my goal being antenna experimentation). 

Does anybody have any ideas how I might be able to do flexible PCBs on my own? (the main thing I want is nonplanar PCBs, in various shapes, and connect to them in a durable manner.

Once in the right shape, they likely would not need to flex a lot.)

Is it possible to do toner transfer or something like that to make them?

Thank you!
« Last Edit: November 15, 2017, 02:07:51 AM by cdev »
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Offline Kean

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Re: Etch one's own flexible PCBs somehow?
« Reply #1 on: November 15, 2017, 02:31:28 AM »
You could try etching it as a normal copper PCB but using the really thin (0.25mm/0.01in) FR4.  It will flex a fair bit, but not quite as much as real flex PCB.
A cheap source is Electronic Goldmine, so depending on where you are located it could be worth ordering some from there to try.
http://www.goldmine-elec-products.com/products.asp?dept=1034
 

Offline jmelson

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Re: Etch one's own flexible PCBs somehow?
« Reply #2 on: November 15, 2017, 07:47:23 AM »
I would like to somehow DIY flexible PCBs using some fairly low tech/cheap method (my goal being antenna experimentation). 

Does anybody have any ideas how I might be able to do flexible PCBs on my own? (the main thing I want is nonplanar PCBs, in various shapes, and connect to them in a durable manner.
I have done some flex PCB prototyping.  I have a regular PCB setup, with laser photoplotter, dry film laminator, exposing frame and spray etcher.  So, I did it just like a regular PCB.
I made master artwork on the photoplotter.  You could use transparency film on a laser printer, or toner transfer, although the results would be a bit rougher.  If you really want to do toner transfer, I recommend getting ordinary PCB technology working reliably FIRST, as the materials are so much cheaper, and only THEN trying the flex.  You can buy flex material on eBay.

Then, I laminated the dry film resist to the flex material, exposed to UV through the master artwork, developed the resist and etched in the etcher.  Worked like a charm!  But, the material, EVEN on eBay, is pretty expensive!

Jon
 

Online cdev

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Re: Etch one's own flexible PCBs somehow?
« Reply #3 on: November 15, 2017, 01:36:55 PM »
I do have regular PCBs working now.. but I use an iron to make the toner adhere to the copper. Probably not possible with flex-pcb material, is it? (what I would expect is that the temperature range for the ironing stage would have to be more precise so the toner adhered, but still the flex material didn't melt?)

I could attach a thermocouple to the iron!  :)
« Last Edit: November 15, 2017, 01:38:38 PM by cdev »
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Online cdev

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Re: Etch one's own flexible PCBs somehow?
« Reply #4 on: November 15, 2017, 02:22:08 PM »
Thinner FR4 has less loss at high RF frequencies
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Online blueskull

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Re: Etch one's own flexible PCBs somehow?
« Reply #5 on: November 15, 2017, 02:34:19 PM »
Polyimide and other common FPCB substrates are as good as FR4 in terms of heat handling. Don't worry, toner transfer won't kill them.
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Offline HalFET

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Re: Etch one's own flexible PCBs somehow?
« Reply #6 on: November 17, 2017, 07:39:56 AM »
Polyimide is extremely forgiving in processing, just keep in mind that it stretches quite a bit and curls up if you heat it. Over 30 cm you can get about 200 micron shrink/elongation depending on what you did to it. But contrary to common believe, polyimide flex is also dirty cheap, roughly same price as FR-4 per square meter in large volume.

My advice: just buy a roll of ShengYi SF305 (adhesive based): http://www.syst.com.cn/en/product_info.aspx?id=36 (Datasheet: http://www.syst.com.cn/UploadFiles/file/201703%E6%8C%A0%E6%80%A7%E8%A6%86%E9%93%9C%E6%9D%BF/201703041038020937500-P5-305.pdf ) It's an adhesive based FCCL but of fairly good quality, if you want excellent quality you can get the Dupont or UBE flex I suppose. But if you pitch in with a few people for parts of a roll you could easily get a few square meters of flex per meter for 100 bucks each.
 

Offline cleaningOut

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Re: Etch one's own flexible PCBs somehow?
« Reply #7 on: Today at 03:59:55 AM »
Pyralux is used for this, but it's quite expensive unless you get free samples. I've tried toner transfer on it, but it's a bit more fiddly than normal copper as it's so much thinner. You don't want to fold/roll the sheet in the etch or the toner will flake off.
 

Online cdev

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Re: Etch one's own flexible PCBs somehow?
« Reply #8 on: Today at 04:52:05 AM »
What about afterward, is it durable? I want flexible not so much for the flexibility as for the shape. I want to be able to do shapes that flat PCBs likely cannot do.
Pyralux is used for this, but it's quite expensive unless you get free samples. I've tried toner transfer on it, but it's a bit more fiddly than normal copper as it's so much thinner. You don't want to fold/roll the sheet in the etch or the toner will flake off.
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