FFC/FPC cables and vibration in machinery - Page 1
Forum section: electronics / projects

author: Simon
author_rank: Unknown
timestamp: September 20, 2023, 12:17:16 pm
content: Does anyone have any good or bad experiences of FFC or FPC cables in equipment with motors and the vibration in the machine. I suppose you would call this materials handling equipment.Are they suitable for this sort of environment as a board to board link that does not have any means of fixing the cables down along the path.

author: KaneTW
author_rank: Frequent Contributor
timestamp: September 20, 2023, 01:50:58 pm
content: A good micro-coax or FPC/FFC connector (eg I-PEX CABLINE for ucoax, EVAFLEX 5-SE-G for FPC/FFC) will be resistant to vibration, but it's going to be less reliable than a proper industrial connector such as M12.

author: coromonadalix
author_rank: Super Contributor
timestamp: September 20, 2023, 03:20:04 pm
content: in some case i used removable silicone, when dried it provide sufficient strength to hold the fpc ...and help if you ever need to remove it ??

author: PlainName
author_rank: Super Contributor
timestamp: September 20, 2023, 03:30:38 pm
content: Garmin satnavs use FFC cables to connect display to processor board. The environment isn't too vibratory in a car but on a bike it can be pretty bad (mine shakes some much over poor road surfaces I'm convinced the mount is about to break off). Seems to work OK for them.

author: Simon
author_rank: Unknown
timestamp: September 20, 2023, 07:43:13 pm
content: Quote from: PlainName on September 20, 2023, 03:30:38 pmAnd I am sure that the cable follows a nice laid out route not just arching across space from one board to another.

author: temperance
author_rank: Super Contributor
timestamp: September 20, 2023, 08:16:57 pm
content: For most connectors, micro vibrations will cause fretting. A way to avoid this is securing the cable such that vibrations don't "reach" the connector.Lot's of information on the subject can be found by searching for "tin fretting corrosion"

author: PlainName
author_rank: Super Contributor
timestamp: September 20, 2023, 08:50:06 pm
content: Quote from: Simon on September 20, 2023, 07:43:13 pmThere is nothing securing it except the PCB sandwich. There is no way to secure it because it connects the PCB in one half to the display in the other half, and it's loose so you can snap the connectors closed and then put the two halves together. It is folded back on itself, but obviously respecting minimum bend radius.

author: Simon
author_rank: Unknown
timestamp: September 21, 2023, 07:15:50 pm
content: PCB sandwich? you mean it is constrained in some way.

author: PlainName
author_rank: Super Contributor
timestamp: September 21, 2023, 07:44:07 pm
content: It connects one PC to another, and they are mounted in opposite halves of the shell. Thus, when closed, the PCBs are facing each other and the FPC forms a loop within that space. Although, actually, the display side doesn't have a connector per se but extends the FPC into a chip-carrying rigid (or vice versa if that's your preference). I'll try and find a photo - prefer not to take mine apart yet again![Later...]Here's a battery replacement video, at 8:02 showing the connection. They all seem to use FPC but the details differ between models. This is typical, though.https://www.youtube.com/watch?v=VC1UoaQ6--8?t=137

author: Simon
author_rank: Unknown
timestamp: September 21, 2023, 07:49:03 pm
content: OK, so much more braced than we would have done. For starters that starts out as a wide fixed cable. not a 6 way ribbon with a connector each end.