Where to buy 125 degree C FFC? - Page 1
Forum section: electronics / projects

author: rcbuck
author_rank: Frequent Contributor
timestamp: July 10, 2025, 10:16:23 pm
content: Does anyone have a link to a company who sells FFC that is rated for 125 degree C? I need a 14 or 16 position one that is 3 or 4 inches in length.

author: TimFox
author_rank: Super Contributor
timestamp: July 10, 2025, 10:28:19 pm
content: You mean "flat flexible cable"?That abbreviation is not very well known.

author: Benta
author_rank: Super Contributor
timestamp: July 10, 2025, 10:42:02 pm
content: Everyone loves TLAs. Not.

author: rcbuck
author_rank: Frequent Contributor
timestamp: July 10, 2025, 11:36:54 pm
content: Quote from: TimFox on July 10, 2025, 10:28:19 pmYes, flat flexible cable. Also, now looking for a connector. The Hirose connector I found is 0 stock at Mouser and DigiKey.(edit)I'm also open to using another connector solution as long as it doesn't exceed 2.54mm pitch for the pins and it is 125C rated. But, any solution will have to be available with pre-made cables. I do not want to be crimping pins for connectors.

author: thm_w
author_rank: Super Contributor
timestamp: July 11, 2025, 01:24:35 am
content: I only see polyimide ffc cable rated for 105C, obviously the copper and polyimide can take it so maybe its a limitation of the adhesive.JLC I don't see any spec for their flat flex in terms of temperature.

author: voltsandjolts
author_rank: Unknown
timestamp: July 11, 2025, 02:40:18 pm
content: FEP ribbon cable maybe.https://www.mouser.co.uk/new/molex/tempflex-flatfepribbon/

author: tooki
author_rank: Super Contributor
timestamp: July 11, 2025, 03:00:32 pm
content: Quote from: TimFox on July 10, 2025, 10:28:19 pmHuh?!? What makes you think that? It’s the standard name for those things.FFC = flat flexible cableFPC = flexible printed circuit (something sometimes confused with FFCs)

author: rcbuck
author_rank: Frequent Contributor
timestamp: July 11, 2025, 03:57:29 pm
content: Quote from: Benta on July 10, 2025, 10:42:02 pmSo if I am asking about a printed circuit board, I should not use PCB, but instead say printed circuit board every time I reference the printed circuit board?

author: rcbuck
author_rank: Frequent Contributor
timestamp: July 11, 2025, 03:58:53 pm
content: Quote from: voltsandjolts on July 11, 2025, 02:40:18 pmYes, it is starting to look like that may be the only solution.

author: TimFox
author_rank: Super Contributor
timestamp: July 11, 2025, 04:04:07 pm
content: Quote from: rcbuck on July 11, 2025, 03:57:29 pmIn careful writing, especially with uncommon abbreviations (even if the writer knows the abbreviation), it is good practice to spell out a term on its first appearance, and use the abbreviation for later appearances.There are other meanings for the abbreviation “PCB”, even if the context implies which one you mean.Scientific publications usually enforce this: I remember when “TTF-TCNQ” was a hot research topic, but Physical Review mandated it be spelled out in the article title.The interested reader can look up that abbreviation to find the full name.

author: tooki
author_rank: Super Contributor
timestamp: July 11, 2025, 06:28:32 pm
content: Quote from: TimFox on July 11, 2025, 04:04:07 pmSure, but a) this is a web forum without an editorial board, and b) because it’s a topical forum, the context is kinda given. (E.g. thedefaultmeaning of PCB here is “printed circuit board” and not “polychlorinated biphenyls”, whereas if this were a forum for linemen or environmental scientists, the default meaning would be “polychlorinated biphenyls” and not “printed circuit boards”.)In electronics, FFC is a common term, not some obscure, rare thing.

author: tooki
author_rank: Super Contributor
timestamp: July 11, 2025, 06:37:22 pm
content: Quote from: rcbuck on July 11, 2025, 03:58:53 pmIs that thin enough, since your original request is for a FFC? If so, that’s certainly a great option, since you can apply regular IDC connectors to it with a bench vise, parallel-action pliers, etc.Otherwise, there are companies that can make high-temp FPCs you could use as an FFC, for examplehttps://www.multi-circuit-boards.eu/en/products/printed-circuit-boards/flexible-pcb.html

author: voltsandjolts
author_rank: Unknown
timestamp: July 11, 2025, 06:49:54 pm
content: Quote from: rcbuck on July 11, 2025, 03:58:53 pmThere is also the option to roll-your-own, using flex pcb from jlcpcb (et al) is quite cheap, and it's polyimide.Edit: Ah, tooki just said the same thing, my bad.

author: rcbuck
author_rank: Frequent Contributor
timestamp: July 11, 2025, 09:18:02 pm
content: Quote from: tooki on July 11, 2025, 06:37:22 pmThickness is not an issue. The main thing I was aiming for is to keep the connector length size small.I think I am going to use a Kyocera AVX 046288016600846+ connector. DK has them in stock and they are rated at 125 C. I will take a chance on the 105 C FFC parts. I put a couple of them in the oven at 150 C and let them cook for 30 minutes last evening. There was no sign of deformation or adhesive release when I checked them.

author: thm_w
author_rank: Super Contributor
timestamp: July 11, 2025, 10:29:11 pm
content: Quote from: voltsandjolts on July 11, 2025, 06:49:54 pmAs I said, JLC has no temperature spec, so you'd have to inquire first.I did find some references to 200C but they've been scrubbed, odd.

author: tooki
author_rank: Super Contributor
timestamp: July 12, 2025, 09:42:53 am
content: Quote from: rcbuck on July 11, 2025, 09:18:02 pmJust beware that it’s not really a valid test. Temperature ratings aren’t about what temperature a product or material can survive, but rather how it performs long-term. (This is why it’s common to see products with a temperature rating that is significantly lower than the temperature allowed as occasional short excursions.) A material that doesn’t show any obvious damage at, say, 200°C for 30 minutes might still fail after 2000 hours at 120°C.One of my favorite types of hookup wire is cross-linked irradiated polyolefin (Huber+Suhner Radox 125 and Radox 155, and Helukabel Helutherm 145). It’s a similar material to heat-shrink tubing. The numbers in all of those are the rated operating temperature in °C. So you’d assume that, like Teflon-insulated wires (often rated to 180°C), they would melt when touched with a 330°C soldering iron. But they don’t, the polyolefin doesn’t even flinch. You can press down on it with the hot tip and nothing happens. It does lose toughness, so you could abrade it away with the hot tip, but not quickly. So why not rate them for 300°C or something? Well, because polyolefin degrades under prolonged heat exposure, turning brittle. Many materials are like that, being slowly degraded by heat, with embrittlement being a common failure mode.In your application, is the 125°C requirement a constant or frequent operating temperature, or just one that it sees once in a while?

author: rcbuck
author_rank: Frequent Contributor
timestamp: July 12, 2025, 06:00:23 pm
content: QuoteIt is a constant operating temperature [automotive under hood(bonnet for UK)] condition.I have decided FFC is not the way to go. Long term reliability is my concern.I will go the ribbon cable route. 125C cable, shrouded headers, and plugs. I am able to find all 3 that are designed to operate at 125C. Molex makes the cable.Various manufacturers make the headers and IDC plugs. The only problem I am having is finding a manufacturer who makes both the shrouded header and the matching plugs for 125C. I keep running into the problem of if they make the 125C header, they don't make the IDC plug. Or if they make the IDC plug, they don't make the 125C header. In some cases they might but the distributors don't stock the matching part and you have to order several hundred.Wurth Elektronik 612014235121 header. No matching plug.TE Connectivity 2-1658527-2 IDC plug. No matching header.Amphenol 75869-102LF header. No matching plug.If those manufacturers do make the matching parts, I have been unable to find them. Possibly someone else is better at uncovering the information than I am.

author: tooki
author_rank: Super Contributor
timestamp: July 13, 2025, 11:39:02 am
content: Quote from: rcbuck on July 12, 2025, 06:00:23 pmAutomotive? Then I’m not sure if any of those are suitable; automotive connectors tend to be kinda specialized. What’s the exact application?

author: rcbuck
author_rank: Frequent Contributor
timestamp: July 13, 2025, 01:32:20 pm
content: It is my design with 2 circuit boards in a sealed aluminum box. The connectors will be used to carry signals between the two boards, so no special connector required. However, i do want the connectors to be rated at 125C.The connections to the outside world do use specialized automotive connectors (expensive).

author: tooki
author_rank: Super Contributor
timestamp: July 15, 2025, 10:35:29 am
content: Quote from: rcbuck on July 13, 2025, 01:32:20 pmWell that’s the thing, even internally you have to deal with many of the same issues: vibration, significant thermal cycling, moisture ingress, fuel and oil vapor ingress, etc. So I don’t think that “no special connector required” is a recipe for reliability.Can you share more about the physical arrangement of the boards? (Orientation, distance, mounting, etc.)

author: rcbuck
author_rank: Frequent Contributor
timestamp: July 16, 2025, 01:46:31 am
content: Quote from: tooki on July 15, 2025, 10:35:29 amBy no special connector, I meant it doesn't have to handle high current or be watertight. The boards are in a water tight, extruded aluminum case. The connectors to the outside world are all water tight IP69K type.The inter-board connectors do have to meet the 125 C rating and need to be vibration proof. The connectors are at the edge of the PCBs at the back of the case. The boards slide into the case slots and are 1 inch apart so the FFC or wires between the connectors would need to be about 3 inches in length.

author: Siwastaja
author_rank: Super Contributor
timestamp: July 16, 2025, 11:29:49 am
content: FFC is IMHO good in high-vibration environment because the connectors have a lot of clamping force compared to the ridiculously small weigh of the cable, and extreme flexibility of the cable itself. Just make sure that the cable, when it wiggles around due to vibration, does not touch any sharp edges or abrasive surfaces!

author: rcbuck
author_rank: Frequent Contributor
timestamp: July 16, 2025, 03:30:33 pm
content: Quote from: Siwastaja on July 16, 2025, 11:29:49 amYes, after a lot of thought and advice from colleagues, I've decided to use FFC connectors. I have found automotive rated connectors. I will have to use flex pcb cables at this point. The connector manufacturers have told me I need to have the cables custom made. JLPCB recommends operating their flex pcb at below 150° C, so it should handle 125 with no problem.If there is off the shelf 125° C flex cable, I haven't been able to find it.