A small soldering question...

[starhawk]

Got my eye on a particular item for a DIY touchpad mouse... specifically this thing.

Here is the image from that auction, with connector details -->

Obviously just a flexi PCB connector. My question is... can I (carefully) rip that POS flexi crap off and replace it with wires, easily? or will I likely damage the touchscreen somehow? As long as (most of) the solder is still around, I can get the wire placed pretty quickly (for me) -- fast enough to avoid scorching anything, but just barely.

Reason for asking is that I really don't see myself learning SMT soldering successfully on that particular item's mating connector -- and you can literally never find through-hole connectors for those damn things, particularly when you want 0.1" hole spacing and that's rather a bit large for the connector's internals!

 

[KrAzYaZnFLiP808]

That point isnt too small at all. If you have steady fingers, and good rosin, should take about 10 mins. Remember to pre tin your wires. Or you will be scorching your board. All it would take is about 3 sec for it to melt, remove iron, and blow/cool it down, 10 seconds you can let go the wire. Its only 4 wires. Make sure you dont short them with the other wires next to them. I have done alot of soldering before, and I can swear by your soldering iron. Its what makes or breaks it.

Here is my link to the thread..

http://shoryuken.com/forum/index.php?threads/how-to-add-led-to-your-te-stick.121405/

 

[starhawk]

What I meant was to remove the flexi PCB and solder to where the flexi bit attaches to the touchscreen.

 

[KrAzYaZnFLiP808]

Re looking at some pics. I do not think it is possible to get to good contact points inside the screen. You would have to chip/dremel away at the bottom of screen and it might cause damage. What I would consider doing is to cut the ribbon short, grab sandpaper, see if you can make the copper come out of the ribbon, tin the ribbon, and solder the wires to their, just making sure they wont short with each other, and pay attention to movement because that can also make it short against each other.

Whats wrong with ribbon cable? Thats the reason they dont use wires because of the moment, and possibilities of it wires coming off.

 

[starhawk]

I guess I could try soldering to the existing connector... it's just, those flexi PCBs are fiddly, ugly, and (as previously stated) thru-hole bread/perf friendly connectors are essentially nonexistent.

 

[KrAzYaZnFLiP808]

Yeah, so true, I couldnt understand you at first, But looking at pics, it seems its inside the glass. and like it just extends the ribbons through the screen, So just the bottom part of the ribbon where it touches the screen I would try to cut, and see if you can get copper to come out, Then tin that.

I have tried pcb trace cutting and fixing before. Its a PITA. Not really fun to do, The Xbox 360 dvd drives where some had to do that, before pcb replacement was made. Thats what essentially where doing. Just trace cutting.

Hopefully all goes well, or try to look for another similar product.

 

[aL Mac]

I would just get the proper connector and solder it by hand. It isn't that difficult. I started out soldering 804 and then 402 parts rather quickly and even a 0.4 mm pin pitch DFN. I don't even have the most steady hands. If you are dealing with very small parts, tweezers and a microscope help a lot.

 

[starhawk]

My hands are steady like a paint shaker and odd angles will make it much, much worse. The other day I repaired my venerable PSION Organizer II (an LA model from IIRC 1987), as it needed a new battery connector, and my skill was so good that there was a pair of brown burnt-flux stains on the PCB when I was done

The kicker is I've got to go back and re-do it with a diode in there, because the old 9v battery connector WAS the reverse-polarity protection for the battery, and the replacement is your average snap -- not gonna work so well there... so diode time. not looking forward to that, not one bit!