Display Glass Requirements for Oxide TFT Technology
An industry need has arisen for oxide TFTs, an advanced, scalable high-performance TFT display technology that meets consumer demand for brighter, faster, more lifelike images. To meet these cost and performance expectations, oxide TFT panel makers need an advanced, thermally and dimensionally stable glass to improve yields while achieving the desired resolution.
Corning LotusTM NXT Glass addresses today’s LTPS-OLED manufacturing process challenges
Corning LotusTM NXT Glass, through its advantaged and balanced glass attributes, was designed to address the challenges of today’s LTPS-OLED manufacturing processes.
Wrap-around electrodes for Micro LED tiled displays
The authors have developed a process to create wrap-around electrodes(WAEs) on glass for use in tiled microLED display applications. The electrodeshave small size and spacing, low resistance, and good reliability. In addition,an opaque overcoat protects the edges of the tiles and reduces seam visibility.These electrodes allow bezel-free tiled operation for high-resolution displays.
Glass Panel Strength and Reliability
Fracture Analysis, a Basic Tool to Solve Breakage Issues (Part I)
Fracture analysis can provide information on both the tensile stress and the origin of breakage. This analytical technique gives important information in determining mechanism of breakage, such as direction of crack propagation, type of the stress, direction of impact and friction, location of the origin.
Behavior of LCD Panel During Bending
When an LCD panel is subjected to pure bending, for example during strength measurement or proof testing, the question arises “does it behave as a monolith of twice the substrate thickness?" or "does it behave as two independent substrates?”. Both theory and experiment suggest that the panel behavior depends on how its edges are held together (i.e. well bonded or loosely held together). Indeed, the former renders the panel nearly twice as strong and four fold as stiff as the latter. This paper will provide the analysis of the bending behavior of a two-layer laminate using St. Venant flexure theory. Experimental data, using strain gages, will demonstrate that an LCD panel can behave either as a monolith of twice the substrate thickness or two independent substrates depending on how its four edges are held together in the support structure including the bezel. The paper derives appropriate equations for computing panel strength when it is bent to constant curvature or when its specimens are flexed in 4-point bending for bothi) well bonded edges and ii) loosely held edges.
Mechanical Reliability of Glass in Curved Displays
This paper explores Corning's approach and recommendations regarding the mechanical reliability of glass for curved displays.
Best Practices in Strength Testing of LCD Glass
This paper provides general guidelines and watch outs while conducting strength testing on LCD glass. Importance of failure modes, large deflections, membrane stresses, failure locations, device design, fatigue, fractography and strain gauging are discussed in this paper. It also gives an example on why panels cannot be treated as monolithic glass when calculating the strength
Four Point Bending of AMLCD Panel
The four-point bend test is used extensively to measure the edge (and surface) strength of AMLCD displays both in panel form and single substrate. The subtleties of four-point bend test for AMLCD panel applications and how one might use additional techniques, such as strain gage, finite element modeling and failure mode analysis, to better understand the data generated, are investigated. This paper attempts to show the following: i) the standard four-point bend equation (FIgure 1) is not applicable to thin AMLCD panels, ii) the edges and surface experience dfiferent stress, iii) stresses can be quantified by knowing break location and the appropriate strain level and iv) failure mode analysis can support the strain analysis and provide valuable information to the experimenter.
Strength Measurements of Thin AMLCD Panels
The biaxial strength using ring-on-ring (ROR) test and uniaxial strength using 4-point bend test (4PB) were measured for 13.3” panels with substrate thicknesses ranging from 0.25 mm to 0.5 mm. The effect of the thinning process was quantified by this data, along with identifying break sources using fractography. Strain gages were used to convert failure load to strength.
High Strength, Damage Resistant Display Panels
Chemical etching can significantly increase the strength of surfaes and edges of display panels. This can be done in a selective fashion by targeting the desired region in need of increased strength. If done properly, the strength increase can be greater than ten times the original strength with values in excess of 1 GPa.
The Mechanical Reliability of Glass Displays in Bending
The mechanical reliability of glass under stress is controlled by the strength of the existing flaw population and the subcritical growth of those flaws under stress. Each glass application requires a mechanical reliability strategy that is optimized for that application. The purpose here is to establish that strategy for the case of glass in displays where the intent is to bend the display permanently. Fracture mechanics is used as a well-established framework for combining strength and fatigue effects on display glass sheets.
Glass Processing - Mechanical
Analytical Approach to Evaluate Maximum Gravitational Sag and its Variations of Glass Substrate for LCD
We present analytical formulas to evaluate the gravitational sagof glass substrate for Flat Panel Displays (FPD). The formulas are derived for the parallel line supports (knife-edges). Past studies and comparison with finite element analysis in this paper show that a continuous line support is a very close approximation to collinear point supports with the kind of support spacing typical in todayscassette designs. Two, three and four supporting lines are considered. A new concept of initial shapes of the glass substrate is introduced to enable evaluation of sag variations caused by various process factors analytically and numerically. We show that both the sag magnitude of the glass substrate and its variations due to various process factors may be drastically decreased with increased number of horizontal supports. The analytical results are verified numerically with the finite-element method.
Optics / Mura
Panel Stress Determines Light Leakage in Curved LCD
Substrate stress state determines the light leakage (LL) from dark state VA and IPS liquid crystal (LC) curved panels. Membrane stress creates VA but not IPS LL. Shear and bending stress create IPS but not VA LL. This result enables mitigation, design, and possibly new processes/components to enable non-traditional form factor LCDs.