Question about soldering flexible display connections... - Page 1
Forum section: electronics / projects

author: alank2
author_rank: Super Contributor
timestamp: November 18, 2014, 10:38:22 pm
content: Hi Everyone,So every once in a while I see some flexible connection like this:http://www.ebay.com/itm/0-96-SPI-Serial-Blue-128X64-OLED-LCD-Display-Module-for-Arduino-STM32-51-AVR-/251658066039?pt=LH_DefaultDomain_0&hash=item3a97fd5877I can see the pcb pads look pretty normal, but how do you solder this? Pre-tin the pads and press it down and heat the solder again?Also, how is something like this soldered automatically using a SMT process?Thanks,Alan

author: alank2
author_rank: Super Contributor
timestamp: November 19, 2014, 07:11:55 pm
content: Any thoughts?

author: Ton
author_rank: Regular Contributor
timestamp: November 19, 2014, 08:14:53 pm
content: Hi Alank2You would use a Hotbar reflow systembasically you add solder to both surfaces, then place the hotbar on top of connection, apply heat to the hotbar so solder melts (10-15 sec.), making sure all pads get connection due to the pressure from the hotbar, then remove heat, wait a bit(another 10 sec or so), until solder solidifies, then releave pressure and remove hotbar.job is a good one O0only problem is this is an industrial process, not realy easy to DIY.here are a short youtube vid of the processBR Ton

author: Ton
author_rank: Regular Contributor
timestamp: November 19, 2014, 08:34:31 pm
content: Hi Alank2Another method that is a bit more DIY friendly could be Conductive PSA (Pressure sensitive adhesive)The idea here is that the adhesive gets compressed more at the pads and therefore gets conductive, but in the space between pads itis not compressed (so much), and therefore does not get conductive.I have not tried this method !Here is a link to a datasheet at Adafruit that explains the processhttp://www.adafruit.com/datasheets/3m%209703.pdfthe Conductive PSA in the link is a 3M product made especialy for this purpose.BrTon

author: Precipice
author_rank: Frequent Contributor
timestamp: November 19, 2014, 08:40:14 pm
content: Just overlap it, line it up supremely carefully and solder it. It'll take a while, and need plenty of liquid flux.Beep it out for shorts before powering it up, but if you're not utterly hamfisted (and use plenty of flux, did I mention that?) you'll be fine.Production uses a hot bar machine that applies pressure over the whole thing, then a short pulse of heat, then lets it all cool still under compression. You don't want to do that, it's a process that needs tuning.

author: Howardlong
author_rank: Super Contributor
timestamp: November 19, 2014, 08:52:52 pm
content: I just made you a video of how to do ithttp://youtu.be/gi-44SDc4dsThe cable is made from Kapton so it won't melt when soldered.I've also tried using a hot air iron but I couldn't get it to work.Note that if you look towards the end I test both the continuity and for adjacent shorts by staggering alternate probe movements.Cheers, Howard

author: dannyf
author_rank: Super Contributor
timestamp: November 19, 2014, 08:57:18 pm
content: QuoteIf I had matching PCB traces, I would solder at two ends and then restart from one end, like how you would solder lqfp.As to me, I use thin copper wires (from multi-strand speaker cables for example) and solder them to the cable first and then to pcb. I use tape or glue to fix them afterwards.

author: alank2
author_rank: Super Contributor
timestamp: November 19, 2014, 11:25:41 pm
content: Thanks for the video Howardlong, that looks great.

author: alice-led-display
author_rank: Newbie
timestamp: October 16, 2024, 05:07:44 pm
content: For manual soldering:You can pre-tin the PCB pads.Align the flexible ribbon on the pads.Use heat (a soldering iron or hot air) to reflow the solder and secure the connection.For automatic SMT soldering:Flexible connectors like this are often soldered using a hot bar soldering or thermocompression process, which uses heat and pressure to attach the connector to the PCB pads.Each method ensures the flexible connector is securely bonded to the PCB