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I was tearing down a TFT LCD from a medical device (ultrasound bone healer) for fun and did not understand the function of a component. It's a silver rectangle that sits between the LCD and the ACF location for the FPC. When held up to the light it appears that all the signals flow into this device and then fan out to the rows and columns of the LCD. If I had to guess it looks like some kind of control chip. The aspect ratio of this chip seems terrible for manufacturing (long and skinny). Can someone tell me what this device might be and what it's function is? If it is an integrated circuit how do they manage something like this, it seems very easy to fracture.

Based on the markings I think it's one of these displays: http://www.trulyamerica.com/products/tft-modules/

enter image description here

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  • \$\begingroup\$ @jsotola Connecting what tho? The FPC is ACFed to the glass, so I am not sure that's it. It's also quite rigid. \$\endgroup\$
    – EasyOhm
    Commented Oct 8, 2019 at 5:47
  • \$\begingroup\$ @jsotola It is not a connector, see my answer. \$\endgroup\$ Commented Oct 8, 2019 at 5:51

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That "silver rectangle" is the LCD driver chip.

The silver color is the back of the chip-die which is made of silicon

The function of that LCD driver chip is to take some input signals and drive many outputs which connect to the LCD.

Without the LCD driver all these lines would have to be connected over the connector making that connection unreliable as each line and connection point would need to be very small or you would need a very large connector.

Here's another example of an LCD driver chip:

enter image description here

where it can be clearly seen where there are some inputs but many outputs (note the thins traces).

The technology used to mount such a chip on a flexible PCB is called "chip on flex".

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  • \$\begingroup\$ thanks for confirming. Are there special procedures that need to be used in order to handle chips with such an aspect ratio? \$\endgroup\$
    – EasyOhm
    Commented Oct 8, 2019 at 6:04
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    \$\begingroup\$ @EasyOhm I have no idea. My guess would be that the silicon die is thicker than what is normally used (in packaged ICs) so that it is less likely to crack. To know all the details you'd need to work in a factory where these drivers are made and processed. \$\endgroup\$ Commented Oct 8, 2019 at 6:09

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