[SOLVED] LCD flex ribbon repair

[dv_sa559]

Hi All
I have a problem for repairing a "LCD" that it's ribbon was cut ,and this cut off caused by physically strain and etc...
I will try to repair that.
Would any expert guide me who to solve this disaster. :-(
However i try to heat ribbon by specially tools but i think it need to adhesive material that hold ribbon on the board.
Thanks in advance.

 

[vimalkhanna]

Re: LCD flex ribbon repare

There are two severe problems with flat flex cables .You will need to replace this as repairs may not solve the issue.The guage of the wires being 44/45 swg may be solderable under a microscope .
The other is the finger /comb connectors of the LCD glass .
This may have been displaced to prevent connectivity with the PCB ...This needs a study /inspection under a magnifying glass .

 

[dv_sa559]

Re: LCD flex ribbon repare

Many thanks dear Vimalkhanna for your guidance.
i confused because i think we can't soldering this flex ribbon as you tell.
this ribbon made by plastic and carbon (i think) and there are not solder-able but in the picture that i attached seems solder in the board but its a type of glue.
question is how is this adhesive and how can i find it?
second you say "You will need to replace this as repairs may not solve the issue."
do you mean changing of flat ribbon or lcd completely ? if you mean ribbon,then how can i find it?
thanks in advance.

 

[pranam77]

Re: LCD flex ribbon repare

Ok..looking to your pictures, it is a flexible conductive PCB used as cable which is held to the LCD terminals by heating to certain temperature, and cannot be soldered, or the lcd doesnt have any metal pins to solder with. You may try heating the lcd connector edge with a hot air blower and pressing the conductive PCB while alligning the contacts under a magnifier. Note that over heatng will cause irreversible damage to the LCD. You are at your own. Other option is to use a rubber strip which holds / presses the conductive tape to the LCD contacts and keeps it in place and allign it in such a way that the rubber is slightly pressurised while the cabinet/ PCB is fixed over it.

 

[dv_sa559]

Re: LCD flex ribbon repare

Dear Paranam77
Thanks . you are right , there are 2 way for repairing : 1- heat by certain temperature 2- use a rubber strip
Unfortunately for use rubber strip it must have a port under lcd also lcd and pcb should be on each other, so we don't use this way.
For repair flexible ribbon in first way that you mention it , there is one problem which it needs glue for connect to pcb and we must know there is no adhesive and it's old glue was rotten.

For this problem do i use any glue or we should use special glue?
IF you have other way for repairing this case i will appreciate your advise.

 

[Kociubinska]

Re: LCD flex ribbon repare

Very good and helpful answer. I have the same problem. Thank you.

 

[Rob B]

Re: LCD flex ribbon repare

You could research Anisotropic Conductive Adhesives such as these products:

http://solutions.3m.com/wps/portal/3M/en_US/AdhesivesForElectronics/Home/Products/SpecialtyTape/AnisotropicConductiveFilms/

Preparation of the surfaces, alignment and pressure while the adhesive cures will be critical.


I accidentally pulled the flex circuit from a printer head mechanism that I was cleaning. It was attached in a similar way but with far less conductors, I managed to heat it back on.

 

[dv_sa559]

Re: LCD flex ribbon repare

Dear Rob B,
many thanks for your advice.
I refer to the site that you mentioned.that is ok , so there is many items that i confused .
in the other words i find that i need to get ACF and ACF adhesive for this case, is it true?

 

[Rob B]

Re: LCD flex ribbon repare

I believe you need just a film, an adhesive paste might be more difficult to apply in a controlled manner but the principle is the same. If I were to try one of these I would use a 200um pitch one (3M™ Anisotropic Conductive Film Adhesive 5363).


Here's how it works, in a slightly different application (chip packaging):

http://www.flipchips.com/tutorial05.html

http://www.hitachi-chem.co.jp/english/products/do/004.html


You would need some way of applying heat and pressure to activate the film.

You might be able to obtain a sample from a manufacturer or reseller :smile:.

How many way is that flex? I was wondering if a FPC socket was available in that number of conductors and pitch.

 

[steven483]

Where on the panel does the ribbon cable connect