Fracture Behavior and Intrinsic Strength of FPD Substrates0 pages

Fracture Behavior and Intrinsic
Strength of FPD Substrates
Technical Information Paper

TIP 203
Issued: November 2004
Supercedes: February 2003
R. A. Allaire and P. L. Bocko
Technology Group, Corning Incorporated, Corning, NY 14831
Paper presented at SID 1996 – San Diego, CA

Abstract
The ultimate practical strength of an FPD depends
largely upon the fracture behavior of its substrate.
Commercial FPD substrates differ substantially in
their response to localized stresses occurring in
panel score and break processes, edge finishing
and packaging. The scoring process, used as a
reliable and inexpensive technique for the sizing
of glass sheets, in particular, can have a substantial
effect upon the strength of the final display. This
paper will review the effect of glass composition
on score behavior and its impact on AMLCD glass
substrates.
Introduction
The choice of the substrate for flat panel displays
directly impacts the strength of the final display.
As FPD technology extends into new applications,
the issue of display strength is becoming
increasingly a priority. This paper will discuss
intrinsic glass mechanical properties and behaviors
in the display fabrication process that control
display reliability.

In a previous paper by the authors1 , a broad discussion
was presented on intrinsic glass properties that can
influence AMLCD robustness. The properties discussed
included thermal expansion coefficient (its effect upon
thermal shock resistance) mechanical properties that
influence the functional strength of glass, and glass
thermal properties that enabled the use of advanced
display component technologies. It was asserted that
low expansion, high strain point glasses with favorable
deformation and fracture properties would optimize the
mechanical reliability of AMLCDs.
Functional Strength of Glass
Failure of glass under load usually initiates at a preexisting surface flaw; therefore, extrinsic factors such as
the quantity and characteristics of surface flaws
determine the functional strength of glass as much as
intrinsic material properties.
Fracture toughness is the material property that is most
commonly used to quantify the intrinsic strength of a
material. When compared to the range of fracture
toughness values for crystalline materials, glasses have