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Mechanical Reliability of
AMLCD Glass Substrates
Technical Information Paper
TIP 204
Issued: November 2004
Supercedes: February 2003
S. T. Gulati and J. D. Helfinstine
Corning Incorporated, Corning, NY 14831
Paper presented at SID 1996 – San Diego, CA
Abstract
Strength, fatigue, and toughness data for five
different AMLCD glass substrates are used,
together with the Power law fatigue model, to
compute their threshold stress intensity KI0. The
relative robustness of LCD displays is assessed by
measuring the flaw depth and computing the safe
allowable in-service stress from K I0, which
ensures the long-term reliability of AMLCD
glass substrates.
Objectives and Background
AMLCD displays are exposed to mechanical,
thermal, and vibrational stresses during
manufacturing, packaging, and in-service1,2 .
Depending on stress-time history and fatigue
properties of AMLCD glass, surface flaws
introduced during manufacturing and handling
may or may not grow thereby impacting the
long-term reliability of displays. Since fatigue
models3-5 have proven valuable in reliable design
of space windows6 , optical fibers7 , telescope
mirrors8 , CRT panels9 , and automotive
windshields10 , it is prudent to apply the same
model to AMLCD glasses and estimate their
threshold stress intensity which plays a critical role in
designing LCD displays from long-term durability point
of view. Several AMLCD glasses were evaluated with
respect to their biaxial strength, dynamic fatigue
behavior, fracture toughness, and flaw severity.
These data, when applied to Power law fatigue model,
provide the safe allowable tensile stress which, if not
exceeded in day-to-day service, would ensure the longterm mechanical reliability of AMLCD displays. These
data are also useful in comparative evaluation of
different AMLCDglasses from reliability point of view.
Results
Table 1 lists the key physical properties of five different
AMLCD glasses which were investigated from
mechanical reliability point of view. Bocko and Allaire1
and Dumbaugh et al11 have recently compared their
thermal, chemical, dimensional stability and edge
integrity characteristics. We extended their work by
focusing on mechanical properties of these glasses,
namely biaxial strength, fracture toughness, stress
corrosion constant, Young’s modulus and Poisson’s
ratio.
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