Desoldering ribbon connectors: Where to start?

[DigiTan]

I have a friend who's considering some repair work on an LCD screen for a graphing calculator. 'Thing is, this repair would require detaching and re-soldering a thin 17-conductor ribbon connector that links the CPU and the LCD driver.

My question is, what's the best way to go about this? I'm assuming a conventional soldering iron would risk melting or scorching the ribbon. I've done a ~little sluething and read about a so-called "hot bar soldering" method that seems promising. But from what I've seen, this is generally an automated process--and we're in need of a more..."home-brew" type of strategy.

Is it possible to make these repairs manually, and if so what are the best approaches? If it helps, this image shows the ribbon being worked on (just above the CPU).

**broken link removed**

 

[williB]

are you sure that both ends of the ribbon cable are soldered?
usually they use that type of cable with a connector on one end..

 

[theboss]

what i would do it to take a bar of copper of equall width of ribbon cable, heat it on a stove till gets hot enought to quickly melt solder. then a touch of that bar to the entire width of the cable and in a second or two, the cable will pull out without transfer of excess heat to surrounding components and risk of damage.

i used this method to pull out a few IC's. worked very well. almost no heating of IC as compared to soldering iron.. for additional protection, i coved the IC with a folded wet tissue paper!!

 

[DigiTan]

are you sure that both ends of the ribbon cable are soldered?

That's correct. From the looks of it, both ends of the ribbon are soldered to directly to the PCB footprinting.

The copper bar technique sound alot like the methods I read about earlier, so I'll give the copper a try!

 

[Dean Huster]

The copper bar method is one of the first desoldering tools made. You used to be able to get a set from Ungar for 7- and 9-pin miniature tube sockets. The problem with the copper bar method is twofold. (1) It sure is difficult to get every single pin to touch the bar simulaneously making you spend more time on the operation than you should and (2) that bar can store enough heat to do some damage if your iron is running too hot.

I'd recommend trying small solder wick first and see what happens. If the cable is lap soldered to the board, an Ungar heat gun with a pinpoint baffle might work well.

Dean

 

[theboss]

i never had problem with copper bar method..

1 - as long as copper bar is smooth
2 - u havent made it soo hot that it is glowing red :lol:
3 - all the pins u want to desolder line up good
4 - u have made proper arrangement to keep the component cool.. usually a wet tissue over the IC or the cable end leaving the desolder subject exposed only.