Etch one's own flexible PCBs somehow? - Page 1
Forum section: electronics / general

author: cdev
author_rank: Super Contributor
timestamp: November 14, 2017, 03:04:40 pm
content: 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!

author: Kean
author_rank: Unknown
timestamp: November 14, 2017, 03:31:28 pm
content: 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

author: jmelson
author_rank: Super Contributor
timestamp: November 14, 2017, 08:47:23 pm
content: Quote from: cdev on November 14, 2017, 03:04:40 pmI 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

author: cdev
author_rank: Super Contributor
timestamp: November 15, 2017, 02:36:55 am
content: 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!

author: cdev
author_rank: Super Contributor
timestamp: November 15, 2017, 03:22:08 am
content: Thinner FR4 has less loss at high RF frequencies

author: HalFET
author_rank: Frequent Contributor
timestamp: November 16, 2017, 08:39:56 pm
content: 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.

author: cdev
author_rank: Super Contributor
timestamp: November 18, 2017, 05:52:05 pm
content: 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.Quote from: cleaningOut on November 18, 2017, 04:59:55 pm

author: HalFET
author_rank: Frequent Contributor
timestamp: November 20, 2017, 09:48:39 pm
content: Quote from: cleaningOut on November 18, 2017, 04:59:55 pmPyralux is just Dupont's brand name for polyimide flex, there are so many grades of it.Yes, flex is durable. If you just want to bend it once and not too extreme go for ED copper with adhesive, if it's for flexing and tight folds go for RA copper and adhesiveless FCCL.