Thin Glass Panels Research Articles

Thin Glass Installation

The architectural prominence of glass structures, driven by ongoing innovations in manufacturing and post-processing techniques, reveals the material's remarkable structural potential. Aluminosilicate glass, distinguished by superior strength and flexibility, particularly in comparison to soda lime glass, facilitates the production of ultra-thin glass with thicknesses as low as 25 μm. This has led to the emergence of "thin glass," defined as any glass below 2 mm in thickness. Thin glass, celebrated for its unique attributes, has found diverse applications in industries like automotive and electronics. In architecture, thin glass holds potential for creating complex, lightweight, and transparent architectural structures. This paper addresses the constraints of thin glass in construction and explores optimal bending techniques to maximize its potential through a detailed study of its properties. The current study establishes design guidelines and a computational approach for utilizing cold bent thin glass in the design process. The findings showcase a successful computational method providing tools, design principles, and guidelines for working with single curved cold bent thin glass panels. The paper also examines suitable connection types for thin glass projects, proposing a hinge clamp connection. A case study illustrates the proposed workflow, resulting in a prototype using a 3D-printed approach for the suggested connection design.

Modeling of ion exchange in glass considering large viscoelastic deformation and mechano–electrochemical coupling

AbstractThis work proposes a theoretical description of ion exchange in glass involving mechano–electrochemical coupling, distinct from the previous models. The generalized Maxwell viscoelastic constitutive relation and large‐deformation formulae are employed, which is indispensable for thin glass panels widely used in consumer electronics. With the theory, two‐dimensional numerical simulations based on axisymmetric and plan‐strain models are conducted. The numerical results signify lateral deformation in a double‐side ion‐exchanged glass and bending caused by single‐side or electric‐field‐assisted ion exchange. With the decrease in glass thickness, the increase in time, or applied electric potential, these deformations become more significant, leading to the relief of in‐plane stresses in the ion‐exchanged layer and the increase in stresses in other parts. This could lead to a remarkable decrease in fracture strength or cracking of an ultrathin glass panel. As the stress and diffusion are coupled, the decrease in stress in the ion‐exchanged layer leads to the increase in the depth of layer of invading ions. These numerical results clearly show the necessity to incorporate the mechano–electrochemical coupling and large deformation in modeling ion exchange, which is uninvolved in previous theoretical models. Moreover, the proposed theoretical model is directly extendable to three‐dimensional scenarios, such as curved or foldable ultrathin glass panels.

Insulation glass units made of thin glass‐polycarbonate composite panels

The combination of brittle thin glass with ductile polycarbonate leads to innovative composite panels. Two outer thin glass panels with one or more inner polycarbonate sheets represent an alternative to conventional laminated safety glass as security safety glazing with a resistance against manual attack. Following development to multi‐pane insulation glazing presents the additional advantages of the composite panel to thermal insulation. This study documents the design of single thin‐glass polycarbonate composite panels as security glazing to multi‐pane insulation glazing with the highest resistance class P8B against manual attack. The paper describes the evolution of the insulation glass unit and the experimental research to reach the defined values of resistance class, heat transfer coefficient and energy transmission. This results in slighter single composite panels and insulation glazing as an innovative alternative to common laminated safety glass as security glazing.

Advanced Low Df Dry film Build-up Material on Glass panel for 5G application

Abstract This paper describes the demonstration of a low loss substrate (laminated glass) for high-frequency transmission using a dry film build-up material with low loss tangent (Df). This paper also evaluates filter characteristics and dielectric characteristics of the substrate in the mm-Wave band. The advanced low loss dry film build-up material was newly developed, and applicable to high frequency transmission. This material has a Df of 0.0025 at 10 GHz and also exhibits excellent adhesion and electrical reliability required for advanced dielectric materials. In addition, glass was used as a core material in this paper because of its excellent signal transmission characteristics compared to silicon wafers or organic substrates. To demonstrate the benefit of low loss materials for high frequency transmission, passive components for high frequency filter substrates were fabricated using - 6-inch square thin (0.2mm) glass panel with various build-up materials (Material A with a Df of 0.0025, and Material B with a Df 0.0042 at 10 GHz) laminated. Copper wiring patterns on the dielectric layers were fabricated by a semi-additive process (SAP). Circuit patterns with low pass filters and band pass filters were also fabricated. First, transmission characteristics and characteristic impedances were measured to check the electrical performance. The measured lowest transmission loss of < 1.43 dB at 39 GHz were achieved when Material A was applied as the build-up material. Second, biased-highly accelerated stress test (bHAST) was conducted to evaluate the reliability performance of the substrates with two build-up materials, Material A and a conventional material. The test condition was based on the JEDEC level 2 standard. The substrate with Material A retained good insulation properties over 300 hours of bHAST treatment, demonstrating its excellent insulating performance. In summary, Material A has been shown in this paper to exhibit reduced transmission loss in high-frequency filter substrates at millimeter wave frequencies.

Thermal shaping of thin glass panels for hard X-ray telescope optics

We present a process for thermal forming of thin glass panels of borosilicate glass to produce mirror segments for X-ray telescope optics. The mirror segments are required to be shaped in a parabolic and hyperbolic shape in accordance with Wolter-I type design of X-ray telescope optics. Thermal forming of glass is a low-cost method to produce light-weight mirror segments. The process makes use of a semi-cylindrical quartz mold having surface roughness of the order of 1 nm. Flat glass sheets of 0.2 mm and 0.3 mm thickness are placed on the diametric edges of the mold. With a suitable thermal cycle, the glass sheets are thermally formed as per the shape of the mold. The shape of these formed glass sheets was measured using a non-contact optical setup. The surface quality measurements of the formed glass sheets were performed using atomic force microscope and they were found to be in the range of 0.04–0.33 nm. Once tested for acceptance, these glass sheets are coated using sputter deposition of multi-layers of high and low atomic number materials for hard X-ray reflection. Such mirror segments do not require polishing of the surface before being coated with multi-layers.

Programmable Granular Metamaterials for Reusable Energy Absorption

AbstractDesigning metamaterials with programmable features has emerged as a promising pathway for reusable energy absorption. While the current designs of reusable energy absorbers mainly exploit mechanical instability of flexible beams, here is created a new kind of metamaterial for reusable and programmable energy absorption by integrating rigid granular materials and compliant stretchable components. In each unit cell of the metamaterial, the stretchable components connect the granular particles to maintain the integrity and control the deformation pattern of the material. When the metamaterial is subjected to an external load, the input energy is partially trapped as elastic energy in the stretchable components, and partially dissipated by friction between the granular particles, forming hysteresis between the loading and unloading force–displacement curves. Through tuning the structural design of the metamaterial, the pretension and stiffness of the stretchable components, and the size of and friction between the particles, a vast design space is achieved to program the mechanical behavior of the metamaterial, such as the load–displacement curve, the multistability, and the amount of energy dissipation. Experimental impact tests on a thin glass panel confirm energy‐absorbing capability of the proposed metamaterial. This design strategy opens a new avenue for creating reusable energy‐absorbing metamaterials.

Improving and Quantifying the Process Window

Abstract Femtosecond lasers bring numerous process‐enabling advantages to precision microprocessing applications. However, taking a new, ultrafast laser‐based application from a first demonstration to full‐blown manufacturing at market‐enabling throughput rates is usually more difficult than for longer pulsewidth lasers. This is because processes utilizing nanosecond (and longer) pulsewidth lasers can rely on a massive knowledge base, built up by laser manufacturers, systems builders and end users, over decades of application. In contrast, femtosecond laser processing is very much in its infancy, with a limited body of proven applications (or even research and development) to draw on. In this article, we describe how a process window was defined, improved, and finalized in the specific case of precision cutting of thin glass panels for display applications.

Design, Modeling, Fabrication and Characterization of 2–5-<inline-formula> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math> </inline-formula> Redistribution Layer Traces by Advanced Semiadditive Processes on Low-Cost Panel-Based Glass Interposers

This paper presents the latest advances in extending semiadditive process (SAP) methods to 2–5 $\mu \text{m}$ lines and spaces, achieved using dry film photoresists on thin glass substrates, toward meeting the routing requirements for 20- $\mu \text{m}$ bump pitch interposers. High-density chip-to-chip interconnections on 2.5-D interposers are a key enabler to meet the high logic to memory bandwidth needs of next-generation electronic systems. Such 2.5-D interposers require ultrafine redistribution layer (RDL) traces with line widths and spacing below $5~\mu \text{m}$ . This paper reports on the extension of panel scale and lower cost SAPs to achieve less than $5~\mu \text{m}$ lines and spaces, based on the ultrasmooth surface and improved dimensional stability of thin glass panels. A modified low-cost SAP method with newly developed differential seed layer etching was employed to fabricate the fine line and space patterns and coplanar waveguide (CPW) transmission on thin glass panels. Fine lines down to 2- $\mu \text{m}$ lines and spaces and CPW lines with signal lengths up to 5 mm and ground-to-signal gaps down to $5.5~\mu \text{m}$ at 15- $\mu \text{m}$ signal widths were successfully fabricated on ultra-thin glass panels. For comparison, the same processes were also applied to a silicon wafer. The signal insertion losses of CPW lines on the glass were 0.024 dB/mm better at 15 GHz than those on the silicon, as confirmed by simulations as well as VNA measurements. The measured insertion loss of 5-mm long CPW lines on glass interposer was 0.7 dB at 10 GHz and matched well to the simulated values.

Innovated Process Integration for Panel Size Glass Substrate Manufacturing for SiP Application

Although Silicon interposer has good performance, however high cost is still the major issue and limits its high volume adoption. Therefore to decrease the assembly cost or develop low cost, high density interconnect interposer technology is the keys to enable 2.5D SiP integration. One possibility is to develop low cost interposer by adopting the alternative materials instead of Silicon. The glass, low CTE polymer material, ceramic, etc. may be included. Glass represents an attractive choice with potential of tailorable properties dependent on specific glass composition. By targeting the coefficient of thermal expansion (CTE), the CTE of glass can be made to match perfectly with silicon dies and for reliable package. In addition, the advantages of using glass for interposer derive from process flexibility for size and thickness since the glass fusion process provides sheets with dimensions of more than three meters. It is straight forward to provide glass substrate of almost any size needed. Large glass panels are ideally suited for fabrication of interposer where the panel process is expected to provide large number of interposers in each run compared with wafer processing. Additionally, the two sided processing of the panel, the avoidance of Si wafer CMP processes further enable lower unit cost for the interposer Consequently, glass is an ideal interposer material due to its insulating property, large panel size availability, high modulus and ability to tailor CTE. In this paper, we successfully demonstrate manufacturing feasibility of glass substrate with 4 build-up layers starting with a thin glass panel in 508mm×508mm panel size format and under the IC substrate manufacturing environment. Glass thickness of 100~300um could be processed through the IC substrate HVM line. The laser via in via or direct metallization technology could be selected for double side electrical connection. The copper line width/space of 8/8um was demonstrated by current substrate HVM line. By adopting advanced lithography process and material, line width/space less than 2/2um was achievable. TCT Reliability test without glass crack results will also be discussed.

High Reliability and High Performance 30μm Through-Package-Vias in Ultra-Thin Bare Glass Interposer

This paper presents, for the first time, the thermo-mechanical reliability and the electrical performance of 30μm through package vias (TPVs) formed by Corning in ultra-thin low-cost bare glass interposers and metallized directly by sputter seed and electroplating. In contrast to glass interposers with polymer coated glass cores reported previously, this paper reports on direct metallization of thin and uncoated glass panels with fine pitch TPVs. The scalability of the unit processes to large panel sizes is expected to result in bare glass interposers at 2 to 10 times lower cost than silicon interposers fabricated using back end of line (BEOL) wafer processes. The thermo-mechanical reliability of 30μm TPVs was studied by conducting accelerated thermal cycling tests (TCT), with most via chains passing 1000 cycles from −55°C to 125°C. The high-frequency behavior of the TPVs was characterized by modeling, design and measurement up to 30 GHz.

Low Cost Glass Interposer Development

For high density interconnection IC packages of the future, the outlook is for thinner packages with higher routing densities. With that, managing the substrate warpage becomes critical. Traditional organic substrates may face several challenges for high density I/Os with very fine line interconnections. Glass is one of the candidates that can be used in substrate industry. The infrastructure of glass for LCD industry has already been developed for many years. Glass also has several superior properties than other substrate candidates, such as large panel size availability, adjustable CTE, high modulus, low dielectric constant, low dielectric loss and high insulating ability. In this paper, we successfully demonstrate early manufacturing feasibility of glass substrate with 4 build-up layers starting with a thin glass panel of thickness of 200μm in 508mm μ 508mm panel size format and under the IC substrate manufacturing environment. Fabrication and electrical results of a test vehicle are documented. The test vehicle includes daisy chains that are connected with 100μm diameter through glass via (TGV) in a 200μm thick glass. The laser via in via technology was adopted for double side electrical connection. The copper line width/space of 8/8μm was demonstrated. The total thickness of 4 layers test vehicle is about 390μm. The warpage of glass in comparison with an organic substrate (BT) with 200μm core thickness is 3X better. Further work is needed to develop, fine tune and assess the detailed manufacturability and reliability concerns. Based on this work, it is clear that the potential of glass in IC packaging and integration is tremendous in diverse applications for substrate warpage enhancement.

Internal modification for cutting transparent glass using femtosecond Bessel beams

Taking advantage of the nonlinear laser-material interaction, femtosecond lasers can process transparent materials internally on micro- or nanoscales, whose applications include fabrication of micro-optical waveguides and fluidics, as well as stealth dicing of glass, ceramics, and semiconductor materials. A femtosecond Bessel beam has a long invariant transverse intensity profile up to several millimeters with a width of a few microns. Such characteristics allow the materials processing to be completed without moving the beam focusing points as in the case of the Gaussian beam. An experimental femtosecond Bessel beam microprocessing system is built up to investigate the glass internal modification characteristics, such as the width variation and aspect ratios of modification areas. The residual stresses in the irradiated area of glass after modification are also studied using micro Raman spectrum. Finally, an application to thin glass panel cutting is demonstrated by the process of internal modification and breaking. The glass panel is well cut with the chipping on the breaking edge <1 μm .

Compressive behaviour of laminated structural glass members

Several experimental investigations in the past few years have highlighted the fact that the compressive strength of glass was significantly higher than its tensile strength, allowing new applications of glass in compression members. However, due to the high slenderness of structural glass elements made of thin glass panels, they tend to fail in a brittle manner. A substantial amount of fundamental research has been carried out in the past few years to investigate the stability behaviour of structural glass elements. However, although buckling of glass panels has been quite well studied, a very poor amount of research has been addressed to glass columns, which by contrast represent the most interesting case due to their direct application in buildings. In this paper, the results of ten compressive tests on glass panels and columns are presented and discussed. The main variables considered were slenderness of panels and the shape of the cross-section for columns. The results of six bending tests on monolithic and laminated glass panels are also shown, and the level of connection between the glass sheets was evaluated. A review of the theoretical background is provided and the results achievable with existing analytical models are compared.

Vibro-Acoustic Damping Simulation of Two Laminated Glass Panels Coupled to Viscothermal Fluid Layer

This paper numerically investigates the vibro-acoustic behavior of two thin film-laminated glass panels coupled to a viscothermal fluid layer. For this purpose, the film-laminate finite element model is coupled to the viscothermal fluid model, introducing an original configuration of a laminated double-glazing system. The two-layer laminated panel finite element is developed using Kirchhoff’s plate theory and by taking into account the shear stress of a confined ultra-thin film at the skin’s interface. Then, the developed equations of the laminated glass panel are based on the theory that introduces a particular behavior rule for an ultra-thin film, which includes effects of stiffness, without taking into account the film thickness. After that, the dynamic model is established in an appropriate form, including effects of viscosity and thermal conductivity of fluid and taking into account the acousto-elastic coupling. Thus, the developed finite element model is defined by a frequency-dependent symmetrical matrix system that is obtained after discretization and minimization of the coupled system energy function. Hence, a modal iterative approach is derived in order to determine the eigenmodes and vibro-acoustic responses of the film-laminated double-glazing system. The validation of the acousto-elastic model is accomplished by comparing the coupled system results against data obtained from the literature. Subsequently, several vibro-acoustic indicators, such as film-laminate strain energies and the transmission loss of the coupled system, for a specified design of a laminated double-glazing system excited by uniform pressure are presented and discussed. The numerical results show the importance of both thin film-lamination and viscothermal fluid effects on double-glazing vibro-acoustic performance.

Increasing the Photovoltaic Efficiency

AbstractDriven by falling prices and competitive pressure manufacturers of photovoltaic cells are seeking for new methods and cell concepts to reduce production costs and increase cell efficiency. Developments which have been of more academic interest over the past years are close to find their way into volume production. While laser applications are already standard for structuring of thin film PV glass panels, they are not yet widely established in the silicon‐wafer‐based cell manufacturing, which still represents more than 80% of the photovoltaic market. However, without adding too much complexity to the process flow most of the new cell concepts are only feasible by introduction of laser processes.

FPD용 공기부상 이송컨베이어 시스템 개발

디스플레이 장치에서 기존의 CRT는 곡면이며 무겁고 큰 부피 때문에 LCD, PDP와 같은 평판디스플레이(FPD)로 대체되고 있다. FPD는 <TEX>$0.6{\sim}0.8mm$</TEX> 두께의 대면적 글래스에 여러 공정을 거친 후에 최종 제품 규격으로 절단하여 제작하기 때문에 글래스의 면적이 크면 클수록 FPD의 생산성이 높다는 밀접한 관계를 갖는다. 따라서 FPD 제조 업계에서는 글래스 면적을 증가시키기 위하여 노력하고 있다. 7세대 글라스(<TEX>$2,220mm\;{\times}\;1,870mm\;{\times}\;0.7mm$</TEX>)를 대상으로 유한요소해석 및 유동해석을 통하여 이송장치, 배급장치, 수평/경사 변환장치 및 제어장치로 구성된 비접촉 공기부상 이송시스템을 개발하였다. 본 개발에서 확보한 설계기술을 통하여 글라스의 크기가 대형화 되더라도 관련 이송장비를 보다 쉽게 제작하여 적용할 수 있다. The CRT(Cathode Ray Tube) displays have been substituted for FPDs(Flat Panel Displays) such as LCD(Liquid Crystal Display) and PDP(Plasma Display Panel) because they have a convex surface, large volume and heavy weight. The productivity of FPDs is greatly dependent on the area of thin glass panel with <TEX>$0.6{\sim}0.8mm$</TEX> thickness because FPDs are manufactured by cutting a large-scaled thin glass panel with patterns to the required product dimensions. So FPD's industries are trying to increase the area of thin glass Panel. Through FEM(Finite Element Method) analysis and fluid analysis, we developed an non-contact and air-floating conveyor system which consists of transport-module, distributor, horizontal/vertical changer and controller for the 7th generation glass panel (2,200mm in width, 1,870mm in length and 0.7mm in thickness). The design technology developed in this study can be effectively applied to a conveyor system for a larger-scaled thin glass panel.

공기부상 FPD 이송장치에서 다공질판과 글래스 사이의 공기유동 해석

최근에 많은 수요와 각광을 받고 있는 디스플레이 장치에서 CRT는 곡면이며 무겁고 큰 부피 때문에 LCD, PDP, OLED와 같은 평판디스플레이(FPD)로 대체되고 있다. FPD는 <TEX>$0.6\sim0.8mm$</TEX> 두께의 대면적 글래스에 여러 공정을 거친 후에 최종 제품 규격으로 절단하여 제작하기 때문에 글래스의 면적이 크면 클수록 FPD의 생산성이 높다는 밀접한 관계를 갖는다. 따라서 FPD 제조 업계에서는 글래스 면적을 증가시키기 위하여 노력하고 있으며, 예를 들면, 현재 8세대 LCD인 경우 약 <TEX>$2,200mm\times2,600mm$</TEX>의 면적을 가진다. 이러한 글래스를 이송하는 대표적인 장치로서 공기부상 컨베어시스템은 압축공기를 이용해서 FPD용 대면적 글래스 등을 약 <TEX>$0.3\sim0.5mm$</TEX> 정도 부상시켜 비접촉으로 이송할 수 있는 장치이다. 이 때 글래스와 다공질판 표면 사이의 공기 유동이 모델링되고 해석되며, 이것으로부터 글래스의 공기부양 조건이 예측될 수 있다. 글래스를 이송시 전기공급 중단에 의하여 압축공기가 공급되지 않아 부상판과 접촉이 발생하였을 때, 자기윤활 특성을 가진 다공질판 위의 글래스는 1mm 홀을 많이 가진 사각덕트 부상판 위의 글래스와 조사, 비교된다. The FPDs(Flat Panel Displays) such as LCD(Liquid Crystal Display) and PDP(Plasma Display Panel) and OLED(Organic Light Emitting Diode), recently, have been substituted for CRT(Cathode Ray Tube) displays because they have a convex surface, small volume, light weight and lower electric power consumption. The productivity of FPDs is greatly dependent on the area of thin glass panel with 0.6 - 0.8mm thickness because FPDs are manufactured by cutting a large-scaled thin glass panel with patterns to the required product dimensions. So FPD's industries are trying to increase the area of thin glass panel. For example, the thin glass panel size of the 8th generation is 2,200mm in width, 2,600mm in length and 0.7mm in thickness. The air flows both in the thin glass panel and in the porous PE-plate surface were modeled and analyzed, from which a working condition was estimated. The thin glass panel on the porous PE-plate surface with self-lubricating characteristics was investigated and compared with that on the square duct floating bar surface with many holes of 1mm diameter when the thin glass panel contacts the floating bar surface due to malfunction of electric power supply.

A Note on Applying the Displacement Method in Assessing Fire Hazard of Glass Systems

Planar thermoelastieity problems have to be solved in assessing the fire hazard of glass systems. The displacement method was proposed to solve such problems. The two-dimensional heat transfer equation will be solved by the Green's theorem. A potential function was derived to give the displacement, strain, and stress. Similar to the Airy stress function, the displacement function used in this article will also satisfy the set of equations concerned. Behavior of thin glass panels in a fire is proposed to be studied by this displacement method in calculating the temperature distribution. Language: en

Active control of glass panels for reduction of sound transmission through windows

This paper explores the development of thin glass panels that can be controlled electronically so as to act as transmission preventers that block the propagation of sound. Small rare earth voice coil actuators are used to control glass panel vibrations. The development of the control system is based on the use of a wave separation algorithm that separates incident sound from reflected sound. The incident sound serves the important purpose of providing an acoustic reference that is unaffected by the action of the control system speaker. This reference signal is used in an adaptive feedforward control system to drive the transmitted sound to zero. Detailed experimental results are presented showing the efficacy of the algorithms in achieving real-time control of acoustic transmission. The glass panels are able to effectively block transmission of sound, reducing sound transmission by 20 dB in the case of tonal frequencies and by 10–15 dB in the case of broadband noise. The glass panels can potentially be of great value in the development of noise-blocking glass windows for homes close to airports and noisy highways.

47.4: Effect of Glass Thickness on Stress in a Centrally Loaded LCD‐TV Panel

AbstractAn analytical solution, based on linear plate theory, shows that the maximum tensile stress in an LCD‐TV panel loaded at the center and simply supported at the four edges depends on several independent factors, namely i) glass thickness, ii) nature of the load, whether static or dynamic, iii) constraints on the center deflection, and iv) details of the cell structure, such as the size, spatial density and properties of the cell spacers and their response to the load. In the case of static load, a thicker panel will experience higher stresses than a thinner panel for identical values of center deflection. In the case of dynamic load, i.e. impact by a spherical ball, the thicker panel will also experience higher stresses than a thinner panel for identical values of center deflection. Experimental data based on strain gages and fractographic analysis of fracture origins are in progress to examine the pros and cons of thick vs. thin glass panels from a mechanical durability point of view. Dynamic loading can induce higher stresses than static loading and hence is a more sever test for mechanical durability.