Rebuild pads for FFC socket - Page 1
Forum section: electronics / beginners

author: mauros
author_rank: Regular Contributor
timestamp: January 28, 2018, 03:37:51 pm
content: Hello everyone!I would like to fix an FFC socket on a pcb where some pads are missinghttps://imgur.com/a/vVOqjBut first I would have to rebuild the missing pads on the pcb and using hot air to weld the FFC. I was thinking of using very thin copper wire but my doubt is if I can fix it with cyanoacrylate. I would read with pleasure your opinion as well as your suggestions on some alternative technique.Best regards

author: mauros
author_rank: Regular Contributor
timestamp: January 29, 2018, 05:59:54 pm
content: up ?

author: mauros
author_rank: Regular Contributor
timestamp: January 29, 2018, 08:42:59 pm
content: Very interesting. Tell me what equipment I need to get myself

author: fourtytwo42
author_rank: Super Contributor
timestamp: January 29, 2018, 08:48:57 pm
content: Woww thats a mess, I guess somebody wasn't very carefull removing the old connector! In any case I would not bother trying to fix the pcb but just resolder the connector back onto the remaining pads then repair the missing connections with thin silver plated kynar fed through the empty via's from underneath where nececery

author: mauros
author_rank: Regular Contributor
timestamp: January 29, 2018, 09:00:53 pm
content: Quote from: fourtytwo42 on January 29, 2018, 08:48:57 pmokQuote from: fourtytwo42 on January 29, 2018, 08:48:57 pmcould you tell me how ?

author: fourtytwo42
author_rank: Super Contributor
timestamp: January 29, 2018, 09:04:40 pm
content: Well you need 30AWG or thinner kynar so it will fit through the via's behind the connector allowing you to pick up the signals that used to be tracked to the front of the pads. Things that used to connect to the rear of the pads are easy to do with the same wire to wherever you can pickup the signal close as possible. Best do the underside problem first maybe.

author: mauros
author_rank: Regular Contributor
timestamp: January 29, 2018, 09:23:31 pm
content: Quote from: fourtytwo42 on January 29, 2018, 09:04:40 pmI did not understand if the kynar is an electric wire or a resin that melts and solidifies. If it's an electric wire, what's the difference with a standard wire ? I already have thin wires.

author: mauros
author_rank: Regular Contributor
timestamp: January 29, 2018, 09:41:29 pm
content: Quote from: fourtytwo42 on January 29, 2018, 09:04:40 pmI did not understand what you mean "front of the pads" and "via's behind"

author: mauros
author_rank: Regular Contributor
timestamp: January 30, 2018, 01:11:44 pm
content: Sometimes, certain things are not easy to understand only by writing. What I understood from what you wrote is that instead of taking the signal in front of FFC, I can use a wire that runs from behind the FFC connector. If so, however, escapes me a thing since the FFC i have to place it over the wire to weld it with hot air, but when the tin will melt the FFC a little will lower and it could create a short circuit between the pads. But surely I misunderstood.

author: mauros
author_rank: Regular Contributor
timestamp: January 31, 2018, 12:32:49 am
content: up

author: fourtytwo42
author_rank: Super Contributor
timestamp: January 31, 2018, 03:45:31 pm
content: Kynar wire is semi heat resistant, it does not shrink back like pvc, look it up on the web. 30awg is a fine size and silver plating ensures it solders in the minimium time. As for the explanation, look at the problem yourself! You can only attach wires to the rear of the connector so how are you going to connect them to the remains of the torn off pads only available at the front of the connector ? You should realise you have to pick them up under the board and then feed the wires through to the top, how ? the convenently placed via's behind the connector (via is a hole). BTW thats how I would do it rather than trying to repair the PCB

author: mauros
author_rank: Regular Contributor
timestamp: February 01, 2018, 07:41:38 am
content: Thanks for the reply.Not all vias match on the other side and some time ago I had already prepared to do a job like that, looking for the individual signals directly on the main of the pcbThe problem is that the FFC must be connected to the flex of an LCD display that does not work and I think that among the 28 pins there could be someone that I have identified incorrectly on the mainboard.

author: mauros
author_rank: Regular Contributor
timestamp: February 03, 2018, 08:04:03 am
content: Quote from: mauros on February 01, 2018, 07:41:38 amto tell the truth, none