FFC but made of very flexible plastic with graphite traces - Page 1
Forum section: electronics / beginners

author: tester43
author_rank: Regular Contributor
timestamp: February 08, 2023, 11:45:27 am
content: Hi,I am searching at farnell or mouser for the cable.I used FFC, but it's not ok as it's not flexible enough and doesn't last long when users are bending it several times.There are cables build on some plastic base (mylar?) with traces made of graphite or something similar. It's very flexible. How is it called? Can't find it since days...

author: inse
author_rank: Super Contributor
timestamp: February 08, 2023, 01:05:22 pm
content: I have seen this kind of cable on displays or membrane keypads.I don’t know if they are available as stock material, I think they are custom made per application.

author: wraper
author_rank: Unknown
timestamp: February 08, 2023, 01:11:28 pm
content: FFC with carbon traces are not durable and are not used for a lot of flexing. Not to say there are not suitable for most of the circuits due to high resistance. You probably need polyaimide based FFC which are yellowish brown.

author: tooki
author_rank: Super Contributor
timestamp: February 08, 2023, 09:18:39 pm
content: Quote from: wraper on February 08, 2023, 01:11:28 pm*polyimide (Kapton), not polyamide.

author: Watth
author_rank: Frequent Contributor
timestamp: February 08, 2023, 09:53:09 pm
content: If it's printed on polyimide, aren't these FPC?

author: wraper
author_rank: Unknown
timestamp: February 09, 2023, 09:33:21 am
content: Quote from: Watth on February 08, 2023, 09:53:09 pmNo, unless it's with components mounted.

author: tszaboo
author_rank: Super Contributor
timestamp: February 09, 2023, 03:55:42 pm
content: First I would bend test a flex PCB. If that can fit your solution, you can just order it to your liking and making it at chinese PCB houses it's also super cheap. If you make it in EU, usually the setup costs are high, but the volume pricing will be similar.

author: tester43
author_rank: Regular Contributor
timestamp: February 10, 2023, 08:57:38 am
content: Somehow I couldnt find the flexpcb option at jlc. Will try againThanks for the hint.FPC based on kapton, searching for that - thanks all

author: tooki
author_rank: Super Contributor
timestamp: February 10, 2023, 09:05:53 am
content: Quote from: tester43 on February 10, 2023, 08:57:38 amJLCPCB doesn’t do flex PCBs.PCBway does them.Quote from: tester43 on February 08, 2023, 11:45:27 amIt comes to mind that if FFCs were failing, a custom flex PCB isn’t going to fare much better. You need to figure out your mechanical design so that the FFC/FPC has sufficient radius to flex without strain. In really high-cycle applications, you need to provide a lot of length to do the bending in. (In laptops, for example, it’s usually a long FPC that is coiled up, so that opening the screen actually just loosens the center of the coil.)

author: wraper
author_rank: Unknown
timestamp: February 10, 2023, 10:58:23 am
content: Quote from: tooki on February 10, 2023, 09:05:53 amNever seen coiled FFC/FPC anywhere. Neither in older mobile phones when slider/flip phones were popular, nor in newer laptops. Thin wire harness is much more reliable BTW, therefore laptops predominantly use that.

author: tester43
author_rank: Regular Contributor
timestamp: February 10, 2023, 06:11:52 pm
content: It's not the radius problem.I had a type of cable (FFC) that has an edge connector on one end and bare traces for soldering on the other one.It works if you are used to handle electronics.But it's a device for retro computer where people tinker a lot.You can imagine, that the part where Traces are soldered to the PCB is a weak point.But! Thanks to the hints here I ordered some samples of FFC / FPC Jumper Cables 33C 0.30MM FF JUMPER PREMO-FLEX LGT 6.00 (Molex 15015-0633) along with matching sockets FFC & FPC Connectors 0.3 FPC Bck Flip Hsg Assy33CktEmbsTpPkg (Molex 502598-3393). It's made of Polyimide. I will see.The big advantage of this is: it's off the shelf product - I don't have to order the custom cable from somewhere.

author: tester43
author_rank: Regular Contributor
timestamp: February 10, 2023, 06:14:12 pm
content: I checked the pcbway flex pcb. It's nice and all, but the cost is x5 vs the polyimide tape. I will experiment with flat cable first.

author: tester43
author_rank: Regular Contributor
timestamp: February 10, 2023, 06:15:21 pm
content: In my case the limitation is the size of connector. Connector must fit within 1.6mm height. So flat cable is the way to go as I see it.