LCD Sitronix ST7528 IC Controller Failure Analysis

Gideon Analytical Labs received three failed and three operating Sitronix ST7528 LCD controller/drivers mounted directly on glass and connected via a 24 pad polyimide flex circuit to an FRU controller card. The failed units had a date code 06114A*C3 on a white label, version 1.6.

These are the test point pads on NG1. These are output pads. There is an EOS (electrical overstress) under the glass just below the second rail.

There is a direct correlation between the failures and the EOS found on the die at the test point pads. The good die had no EOS on any of the test point pads with the same date code. Since these test points are output pins, this would imply the circuitry associated with these test pads have seen too much power also. This would inherently raise a concern over reliability and latent damage on the die prior to use. Since these test pins are not connected in any way to the application and a connection must have been made to make them fail, then the testing must have occurred at the manufacturer, Sitronix.

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