Soldering flex PCB to a PCB, have you tried it?

[TimB]

Hi,

I'm engaged in the thing I like most, planning new products.
Currently I'm looking at a monochrome LCD using a 240 x 160 lcd from my favourite supplier (buydisplay.com)

They have just the part I want. But it comes in 2 varieties
Ver 1 has the cable from it to the PCB going to a zif connector https://www.buydisplay.com/3-4-inch-graphic-touchscreen-lcd-cog-module-240x160-single-sided-fpc

Ver 2 did not seem to have a connector available https://www.buydisplay.com/3-4-inch-240x160-dot-matrix-lcd-display-serial-interface-black-on-white 

Then I read the info and it seems to be a solder-able connector. I currently use a LCD with a zif. Not a real issue apart from soldering the connector. Never used the solder-able type. No idea what to expect!

Any tips should I use that or the zif. BTW I do not need the touch screen options, so that is not the deciding factor.


 

[Giuseppe]

I don't have much experience of soldering on flexible pcb, surely you have to be very careful to rest the soldering iron tip for a very short time on the flexible pcb pads. Or you have to buy the connector to be soldered on the normal pcb and then connect the flexible pcb without problems.

[top204]

If it is Chinese advertising that states "solderable", make sure that they have not mistaken "Soldering" and "Welding", as they sometimes do. Most of those types of flexible connectors are vibration welded with ultra-sonic vibrations. That's why, over time, LCD televisions "pack in" because the connectors come loose from the PCB because they are vibration welded and not soldered, so they are not as long lasting.

With that type of flexible connector, it cannot, easily, be soldered with a soldering iron, otherwise, the plastic around it twists or contracts etc, because of the localised heat It has to be done in a controlled temperature soldering line that gradually increases the temperature, then gradually decreases the temperature.

[flosigud]

I repaired few cameras in last century. Some of the then current cameras had flexible pcbs that in some cases had to be desoldered and then soldered again. We just did that with an ordinary soldering iron. Few years back I had a TFT giving me black screen. I resoldered the flex as earlier and it lit up.

[TimB]

flosigud

Did you just just place the soldering iron on the flex PCB? The Flex PCB on the LCD I want to use has the solder section ~ 1mm from the edge with an insulated end.

It would be good to tin the pcb and flux the flex pcb then holding it in place solder it down by holding a iron on the top side.

[flosigud]

We did as you say, with a small blob of tin on the tip. In most cases it was flex to flex and some wires to the flex. The flex in these cameras was surprisingly big when unfolded. On another occasion I melted a flex by maneuvering the soldering iron close by but not touching.