LXD specializes in the manufacturing of extremely long life LCD's for those applications in which service life and reliable performance outweigh all other considerations. Our long life LCD's, with temperature ranges as low as -55oc and as high as 122oc, are designed for outdoor applications and others where extremes of temperature and humidity are encountered. These include gasoline pumps, marine instruments, oil exploration devices, and many others.

Our processes have been designed to eliminate two major types of display failures. These include "functional" failures that can be traced to defects in materials or process, and failures that are characteristic of a display's end of life behavior.

The incidence of both types of defects in normal manufacturing is not high, but since the cost of replacing a display can be twenty times its initial cost, and even higher in some outdoor applications, many users prefer an assured longer service life. The higher purchase price usually results in a lower cost of ownership.

"Functional" field failures, typified by seal failures, shorts, open segments, and ghosting, have been eliminated through manufacturing controls. Each type of defect was studied independently and conditions or practices that permitted it to occur have been changed or eliminated. Early "end-of-life" failures (loss of alignment, bloating, high current) have also been eliminated through the use of state of the art materials and the development of improved chemical processing and formulations.

LXD Display Reliability Tests

When LXD relocated its facility to the new Oakwood location at the end of 1990, there were substantial investments in new cleanroom facilities and process equipment. Displays were randomly sampled for various tests over an 18 month time period to verify process reliability and product reliability. Although the test results were not formally published, the following is a summary of the test conditions and results.

Test A - 80oC - Ambient Humidity - Energized Test Conditions

Displays were mounted in zero insertion force sockets on specially designed reliability testing circuit boards on vertically mounted racks. These racks were placed in one of two horizontal flow ovens with temperatures controlled to 80oC +-3oC. Actual mean temperatures for both ovens for the duration of the test was 81.6oC.

A total of 607 displays were tested from 31 randomly selected production lots from 17 different fiscal week time periods. Only displays with pins were selected because of electrical connection considerations. However, this selection is deemed fully representative of all products manufactured, since pin connection procedures are in addition to the standard "edge" connect display manufacturing.

Display drive conditions were a mixture of 3 volt, 5 volt, and 9 volt RMS drives at frequencies of 32 Hz and 60Hz. Different levels of DC offset were present, up to 100mVDC.

Displays were monitored visually twice per week and fully inspected at the end of each test cycle. The following is a summary of that data.

There were no failures of any device. There was some expected polarizer degradation, especially on the 6000 hr. sets tested. The actual displays selected, that had polarizer options that were not designed to meet this extended time/temperature condition, were not considered failures, since the design parameters of this option were exceeded.

Test B --- Temp/Humidity Storage - 80oC/95%RH 2000 hrs.

A total of 75 displays were tested. Only special high stability polarizers were used in this test. No failures were observed. Slight aesthetic degradation of the displays, due to polarizer shrinkage, was expected and observed.

Test C --- -45oC Cold Test - 24 hours

This test was performed on 300 randomly sampled displays to verify that cold temperature voids would not be present. After LXD modified its process, no failures were observed.

Test D --- Thermal Shock 0oC to 100oC

15 cycles were performed on 20 samples from boiling water to ice water. Transfer time was 5 seconds. No failures were observed.

Test E --- "Pressure Cooker" Test - 121oC, 15 psig, Superheated Steam

Destructive bare cell testing (without polarizers) was carried out over a 22 week period in a pressurized steam autoclave. The test is typically for 64 test hours, with 8 hours at pressure/steam/temperature, and 16 hours dwell time during the overnight cool-down cycle. This test continues for 8 days. (For safety reasons, the test is shut off while not being monitored.) 430 displays were submitted for this test. Some samples ran as long as 96 hours. There were no failures of any displays which were representative of manufacturing production.