Making connections to a calculator LCD zebra ribbon cable - Page 1
Forum section: electronics / projects

author: ledtester
author_rank: Super Contributor
timestamp: October 05, 2022, 04:44:24 pm
content: I am attempting to connect to a calculator LCD display through its zebra ribbon cable:It's a paper-like cable and it's not sticky anymore.As you can see from the pic the pitch matches up with the "1.2mm" pads on the blue breakout board.What's the trade name for this type of connector?Any ideas on how to make an electrical connection?Would a product like this work if the pitch matched? I imagine using it as a splice to bridge the existing ribbon cable to the breakout board. It seems it might have an adhesive backing.https://www.aliexpress.us/item/3256803623516576.html

author: james_s
author_rank: Super Contributor
timestamp: October 05, 2022, 05:20:42 pm
content: You could try heat. I've repaired several Gameboy screens by laying a piece of paper over the ribbon and rubbing a hot soldering iron across it a few times.

author: tooki
author_rank: Super Contributor
timestamp: October 05, 2022, 05:30:28 pm
content: Google “anisotropic conductive film”. That’s what this stuff is.More or less out of reach for hobby use.

author: james_s
author_rank: Super Contributor
timestamp: October 05, 2022, 07:17:21 pm
content: I bet some other conductive adhesive would work, although it would be tedious to apply without bridging the traces.

author: tooki
author_rank: Super Contributor
timestamp: October 05, 2022, 11:30:18 pm
content: That’s what anisotropic conductive film, and similar conductive tapes, are for: they conduct electricity from surface to surface, but not laterally. Look for “z-axis conductive tape” such as 3M 9703.

author: james_s
author_rank: Super Contributor
timestamp: October 06, 2022, 12:58:34 am
content: Sure but you said that was out of reach for hobby use. Other conductive adhesives are readily available.

author: tooki
author_rank: Super Contributor
timestamp: October 06, 2022, 08:41:58 am
content: Oops, you’re right, I was unclear. The film is (because of the equipment and processes to apply it), but the adhesive tape isn’t: you use it to bond pads to flat flex. It’s just double sided tape, but which conducts electricity through it without shorting adjacent pads.

author: wraper
author_rank: Unknown
timestamp: October 06, 2022, 08:43:52 am
content: That cable is already dead, conductive silver layer was ripped off when you separated it from original PCB.

author: ledtester
author_rank: Super Contributor
timestamp: October 06, 2022, 05:22:52 pm
content: Quote from: wraper on October 06, 2022, 08:43:52 amThe cable's not dead - I can activate segments by applying a voltage to pairs of pins.I found these videos suggesting that a soldering iron could work:How to replace the flat cable to repair the displayhttps://youtu.be/yrgkRAXzCpoSaab SID2 LCD Hot Bar Installationhttps://youtu.be/U_WZHUrQpG4There are also special tips ("T-bar" tips) designed for this kind of repair:https://www.amazon.com/Actopus-Soldering-Rubber-Replacement-Installation/dp/B01N9ZJ84Dhttps://www.ebay.com/itm/354288312647A screenshot from the second video:

author: gabiz_ro
author_rank: Regular Contributor
timestamp: October 06, 2022, 07:17:53 pm
content: How is connected that cable to LCD?Remove cable,found a way to mount and align PCB and LCD to match PCB pads with LCD pads and use elastomeric connector .https://en.wikipedia.org/wiki/Elastomeric_connectorAlso know as zebra strips,silicon zebra connector,conductive rubber strip ...

author: ledtester
author_rank: Super Contributor
timestamp: October 06, 2022, 08:43:23 pm
content: Quote from: gabiz_ro on October 06, 2022, 07:17:53 pmYes, that's an option. However, in this particular case I'd like to keep the display in its bezel. The display came from a calculator like this one:I have thought about mounting the ribbon cable on a hard surface and then using elastomeric strips to make connects to the pads on the blue breakout board. Would need to fashion a jig (perhaps 3d print one) to hold everything in place.

author: james_s
author_rank: Super Contributor
timestamp: October 06, 2022, 11:07:45 pm
content: Try a little dot of conductive glue on each conductor. If it works you could screw down a block of something to keep pressure on it and give it mechanical strength. You might also find one of those connectors for thin flexible ribbons that has the right pitch.

author: asage
author_rank: Newbie
timestamp: May 09, 2025, 10:13:18 pm
content: I know this is an old thread, but I just came across this same thing for an old multimeter. It was in the garage for years and I guess all the temp changes just weakened the cable and it mostly popped right off. The T bar soldering iron attachment post is what saved the day for me and gave me the silicone idea below. Here's what I ended up doing in the end:Cut the end of the zebra cable off with a razor bladeCarefully scraped the paint like coating off the black conductive strips with a razor blade. Use a multimeter afterward to make sure you didn't go too deep. Hopefully you have extra cable like I did for mistakesUsed some sandpaper to clean up the contacts on the PCBCleaned both the ribbon cable and the PCB contacts with alcoholUsed a silicone sock from my 3d printer as an insulator (any thin silicone should work) for my soldering iron with a chisel tip and set the soldering iron for 150C. I held it in place for about 5-10 seconds and moved in about 5mm increments the whole way across the cable. at 150C I got a very weak adhesion. I increased the temp by 25C and repeated the process to find a good temp. I ended up at 300C which got it attached pretty good. Depending on how thick your silicone is you will probably need a different temp. Thinking back on it I should have gone a little hotter. I have a good connection, but it may pop off again. It just doesn't have that solid adhesion look that the LCD side of the cable has.Plug everything in and hopefully it works!Some other things I tried that failed:Used double side tape and some cardboard shims to push the cable down on the PCB moreTried superglue and quickly pressing down on the cable to make a connection

author: MathWizard
author_rank: Super Contributor
timestamp: May 12, 2025, 11:43:09 pm
content: I wonder, did they ever make big calculator-telephones back in the 80's or 90's ?

author: abeyer
author_rank: Frequent Contributor
timestamp: May 13, 2025, 01:32:02 am
content: Not a very good pic, but:http://www.calcuseum.com/SCRAPBOOK/BONUS/62008/1.htm