Document Type
Thesis
Date of Award
5-31-1987
Degree Name
Master of Science in Electrical Engineering - (M.S.)
Department
Electrical Engineering
First Advisor
Raj Pratap Misra
Second Advisor
S. Pandey
Abstract
This Thesis shows method of comparing the reliability of Liquid Crystal Display Devices by means of accelerated life testing at elevated temperature and relative humidity for two different vendors.
The tests were carried out at three different combinations of temperature and humidity.
1. 77°±1° C and no added humidity.
2. 85°±1° C and no added humidity
3. 98°±1° C and 98+2% relative humidity.
Leakage current measurements were carried out after every 1000 hours for up to 5000 hours for vendor no.l. Measurements were carried at 0, 500, 1000, 2000, 3000 and 5000 hours for vendor no.2. A DC bias of 5 volts was applied to the LCDs during the measurements.
For vendor no.1, the various failure mechanisms on tested LCDs were noted as: the peeling of the top polarizer at high relative humidity and segmental failure due to open contacts in the electrode pattern. The LCDs which were subjected to 98°±1° C and 98±2% relative humidity, failed totally within the first hours of testing. These displays turned dark indicating the destruction of molecular orientation in the LC material due to moisture penetration. The leakage current for the LCDs with borosilicate glass was lesser than the LCDs with sodalime glass. This shows that for the borosilicate glass, the stability is greater compared to the sodalime glass.
The failures observed for the LCDs from vendor no.2 gives a much higher failure rate. Most of these failures occurred near the sealant end of the displays indicating improper sealing of the liquid crystal cell. Most of these failures occured during the early part of the testing and recovered later on. The leakage current for the LCDs from vendor no.2 was relatively high at zero hours and gradually decreased as the experiments proceeded in time.
Recommended Citation
Krishnamoorthy, Rajkumar, "Reliability evaluation of liquid crystal displays under accelerated life conditions" (1987). Theses. 3280.
https://digitalcommons.njit.edu/theses/3280
