Another Sony with Tab bond failure. KDL-46S4100.

[lookimback]

Re: Another Sony with Tab bond failure. KDL-46S4100.

Anisotropic tape, That's what I was trying to think of earlier. Here's a video of how it's applied.

https://www.youtube.com/watch?v=biHFJFHpqdM

[ReeceyBurger123]

Re: Another Sony with Tab bond failure. KDL-46S4100.

No, I meant that anisotropic tape is what the tabs are originally adhered with.

Ohh right my bad that's interesting, too bad that they fail so easy.

[lookimback]

Re: Another Sony with Tab bond failure. KDL-46S4100.

No, I meant that anisotropic tape is what the tabs are originally adhered with.

[tom66]

Re: Another Sony with Tab bond failure. KDL-46S4100.

No, I meant that anisotropic tape is what the tabs are originally adhered with.

I thought the tabs were soldered to the board. Anisotropic glue is used for the bonding between the tab and the actual LCD.

[ReeceyBurger123]

Re: Another Sony with Tab bond failure. KDL-46S4100.

I thought the tabs were soldered to the board. Anisotropic glue is used for the bonding between the tab and the actual LCD.

That's what I though ?

[lookimback]

Re: Another Sony with Tab bond failure. KDL-46S4100.

I don't think they're soldered to the board either. They come off clean with a bit of heat. No evidence of any solder left behind.

[ReeceyBurger123]

Re: Another Sony with Tab bond failure. KDL-46S4100.

I don't think they're soldered to the board either. They come off clean with a bit of heat. No evidence of any solder left behind.

But the points of contact wont have the adhesive on either they must be soldered, at a low temp as too much heat would melt the ribbon.

[budm]

Re: Another Sony with Tab bond failure. KDL-46S4100.

I believe they use ultrasonic bonding process. When I was working at Fairchild Semi, we use the ultra sonic bonding to attach the wire to the silicone die.

[tom66]

Re: Another Sony with Tab bond failure. KDL-46S4100.

But the points of contact wont have the adhesive on either they must be soldered, at a low temp as too much heat would melt the ribbon.

You would be surprised what temperature the right materials can survive to. PCBs made of fiberglass can be reflowed at 250C peak

[ReeceyBurger123]

Re: Another Sony with Tab bond failure. KDL-46S4100.

Im integrated in this, going to look up exactly how these are manufactured.

[budm]

Re: Another Sony with Tab bond failure. KDL-46S4100.

I found some info here:
http://www.tianma-usa.com/?mod=techm...&idcat=2&id=61

https://cdn.badcaps-static.com/pdfs/...714cae5852.pdf

http://www.acffilm.com/acf-bonder.html

[sgeorge]

Re: Another Sony with Tab bond failure. KDL-46S4100.

i use bump-ons what i call them. in the hardware section they are used for the bottom of picture frames hanging pictures that is to keep from scarring the wall. i trim them down and stick them on the ribbon cable and the pressure of the frame when installed does the trick. i have fixed several this way it works great for me.

the heat does not seem to affect these as they are kind of a hard plastic. the last i done i used a hot solder iron to shave them down for a tight fit.

[lookimback]

Re: Another Sony with Tab bond failure. KDL-46S4100.

Understanding more about what the actual problem is, i.e. the chip coming loose from the tab, I think I could devise a better way of fixing them. I'm thinking of a thin plastic clip which would go around the tab and which would apply firm, steady pressure on the top of the tab, and the chip. Perhaps it would have to be a metal clip, but insulated. It could be retained with a small screw on each side. In this way, you would no longer be relying on the metal frame and the plastic of the backlight assembly to hold the chip in place. And, if the backlight assembly were flexed during moving or mounting, it would not affect the alignment of the chip. I think the problem with foam blocks, and other methods, is that over time they flatten out, thus applying less and less pressure until finally, there is no longer enough to maintain the chip's contact with the tab. That, and, they can move when the panel is flexed. By preventing intermittent contact, this type of fix could last indefinitely. With this method, I suppose it could become necessary to cut some of the metal away from the area where the clip would be. If the clip were made of aluminum, it could also serve as a heat sink.

[mmartell]

Re: Another Sony with Tab bond failure. KDL-46S4100.

Are we not talking about two separate faults here ? I have a Samsung 46" I repaired sometime ago (tab but now thinking cof) which is beginning a new fault in a different location so I may be tearing it down soon and will try some new things when i do.