Question for the reworkers

[sodderboy]

I have to replace 48 of these:

http://www.farnell.com/datasheets/36123.pdf

They solder on under the plastic flexi PCB, so I don't know how they got there. Solder glue?

I'm going to farm it out to someone with skills, but Is this even within the realm of SMD  rework?
Mike

 

[JohnRoberts]

LCDs are low current, some of the connectors are just conductive rubber sandwiched between LCD and PCB fingers.

JR

 

[sodderboy]

That is an OLED with a flexi PCB out to the contacts, which face down and connect to the main PCB
Mike

 

[joaquins]

Hot bar? (like a soldering iron but withe and solder all the pins at once) Those solder joints are a quite common fail AFAIK for displays of all kind, except CRT of course...

JS

 

[sodderboy]

That would work, but the solder connection is UNDER the plastic flexi-strip.  That is what has me confused.

It looks like this guy is heating through the plastic.

Mike

 

[joaquins]

That's exactly what a hot bar does but all at once and with even pressure. The problem is alignment most of the time, just a bit out and you can have one or even multiple shorts.

JS

 

[Andy Peters]

That would work, but the solder connection is UNDER the plastic flexi-strip.  That is what has me confused.

It looks like this guy is heating through the plastic.

Mike

Doesn't the display have a flex-circuit output which connects to the main board with a flat-flex connector? Lift a little tab with your finger, and the flex pops out. Replace the display, plug in the flex and pop the tab down and it's locked into place.

But if the flex is soldered to the board, that's a different story.

You need a board preheater (something like this, which goes underneath the board (or it has a built-in jig which holds the board) and a hot-air tool. The pads are underneath the connector, so you preheat the board to something like 150º C. Then use a hot-air tool at maybe 250ºC to melt the solder. As you're heating the part, wiggle it carefully with a pair of tweezers. At some point the solder will melt and the part will pop off.

Clean the pads on the board with solder wick or some such. Let it all cool down. Put solder paste on each of the pads. Position the part. Start the board preheater, and let it soak at 150ºC for a minute. Then with the hot-air tool, raise the temperature of the part. Watch the part ... once the solder melts, it will slightly rise up and then settle into the pads. Don't touch it with tweezers or anything! Remove the hot air, then dial back the board preheater. Let it cool in ambient air.

-a

 

[JohnRoberts]

Looking at the video it looks like he is soldering through the plastic film... I suspect the doesn't linger with the iron touching the film.

Not how they do it in production for sure.

JR

 

[joaquins]

Real deal
https://www.youtube.com/watch?v=sSeU82jxc-0

Animation
https://www.youtube.com/watch?v=pOA6VnU8CR8

JS

 

[sodderboy]

"Hot bar" brought many links that schooled me.  I am on to some local re-workers who have the machine necessary.
I might do it by hand with a one-off, but 48 pieces requires the correct tool and skilled operator.
Thanks!
Mike