High Long-term Reliability Research Articles

Optimizing energy density in dielectric elastomer generators: a reliability-dependent metric

Abstract Dielectric elastomer generators (DEGs) are soft transducers capable of converting mechanical energy into electrostatic energy. Increasing the mechanical stretch amplitude and the electric field imposed to the DEG leads to higher energy conversion at the cost of a reduced lifetime. Here, mechanical fatigue and electrical degradation were assessed on a silicone-based DEG, and the outcome was used to build an electro-mechanical reliability model. A novel metric, termed levelized energy density, has been introduced to carefully balance the conflicting objectives of high energy output and long-term reliability. Through a multi-dimensional anaylsis of this index, the optimal operating parameters (stretch amplitude and electric field) that maximize energy conversion can be derived. Energy densities reported in literature are generally obtained after pushing the DEG close to their intrinsic limits for a limited number of cycles. In our approach, more realistic values in the endurance domain are presented, which typically leads to a 9-fold decrease in energy density for a design life of 1 million cycles. This article not only addresses the challenge of optimizing DEG performance but also emphasizes the importance of considering realistic operational conditions to enhance reliability, ultimately contributing to the practical and sustainable deployment of these soft transducers in various applications.

Optimization of TLPS Bonding Process and Joint Property using Ni-Sn Paste for High Temperature Power Module Applications

Recently, as interest in eco-friendly vehicles such as electric and hybrid vehicles increases, the demand for power semiconductors, a key component, is also increasing. Power semiconductors convert, distribute, and control power and operate in harsh environments such as high temperature and high pressure. In order to ensure stable reliability in such harsh environments, research on a technology that can stably form joints even at high temperatures is essential. Transitional liquid phase (TLP) bonding was proposed as a high-temperature power semiconductor chip bonding technology, which has the advantage of forming an intermetallic compound (IMC) phase with a high melting point at the joint. However, it takes a long time to convert the joint into full IMC phase. Therefore, in this study, in order to shorten the process time, a paste was manufactured by mixing high-melting point Ni metal powder and low-melting point Sn metal power, and a joint was formed through a TLPS (Transition liquid phase sintering) bonding using the paste. Pastes of different compositions were prepared by adjusting the ratio of Ni and Sn powders. The chip and substrate were bonded through a thermocompression (TC) bonding process, and the highest shear strength was obtained at a bonding temperature of 250 ℃ for 10 min. Heat treatment was performed at 200 ℃ for up to 500 h to evaluate the high temperature long-term reliability of the joints. The Ni-Sn TLPS bonded joints remained reliable joints after a long-term aging test at a high temperature of 200 ℃.

A Multimodal and Multifunctional CMOS Cellular Interfacing Array for Digital Physiology and Pathology Featuring an Ultra Dense Pixel Array and Reconfigurable Sampling Rate.

The article presents a fully integrated multimodal and multifunctional CMOS biosensing/actuating array chip and system for multi-dimensional cellular/tissue characterization. The CMOS chip supports up to 1,568 simultaneous parallel readout channels across 21,952 individually addressable multimodal pixels with 13 μm × 13 μm 2-D pixel pitch along with 1,568 Pt reference electrodes. These features allow the CMOS array chip to perform multimodal physiological measurements on living cell/tissue samples with both high throughput and single-cell resolution. Each pixel supports three sensing and one actuating modalities, each reconfigurable for different functionalities, in the form of full array (FA) or fast scan (FS) voltage recording schemes, bright/dim optical detection, 2-/4-point impedance sensing (ZS), and biphasic current stimulation (BCS) with adjustable stimulation area for single-cell or tissue-level stimulation. Each multi-modal pixel contains an 8.84 μm × 11 μm Pt electrode, 4.16 μm × 7.2 μm photodiode (PD), and in-pixel circuits for PD measurements and pixel selection. The chip is fabricated in a standard 130nm BiCMOS process as a proof of concept. The on-chip electrodes are constructed by unique design and in-house post-CMOS fabrication processes, including a critical Al shorting of all pixels during fabrication and Al etching after fabrication that ensures a high-yield planar electrode array on CMOS with high biocompatibility and long-term measurement reliability. For demonstration, extensive biological testing is performed with human and mouse progenitor cells, in which multidimensional biophysiological data are acquired for comprehensive cellular characterization.

Fully stretchable, porous MXene-graphene foam nanocomposites for energy harvesting and self-powered sensing

The growing demand for intelligent wearable electronic devices has spurred the rapid developments of high-performance deformable power supplies such as triboelectric nanogenerators (TENGs) with high output performance. However, the intrinsically stretchable TENGs especially those prepared with low-cost manufacturing approaches still suffer from poor performance. To address the challenge, this paper presents a fully stretchable TENG consisting of an intrinsically stretchable MXene/silicone elastomer and silver nanowires (Ag NWs)-graphene foam nanocomposite. The intrinsically stretchable TENG exhibits high output performance (voltage, current, and power of 73.6 V, 7.75 μA, and 2.76 W m−2), long-term reliability, and stable electrical output under various extreme deformation conditions. In addition to the application on the human skin and clothing for human motion monitoring and detecting the strength training postures, the intrinsically stretchable TENG can also harvest the intermittent mechanical energy from human bodies to charge various energy storage units such as commercial capacitors for driving wearable electronic devices. The resulting systems have been demonstrated in applications from home anti-theft to water resources early warning systems, which provide the proof-of-the-concept demonstrations for the next-generation standalone device platforms.

Development of a Reliable High-Performance WLP for a SAW Device.

In this paper, we present wafer-level packaging technology for surface acoustic wave (SAW) filters with higher long-term reliability and better electrical performance. This article focuses on the package structure, fabrication processes, and reliability for the SAW filter wafer-level package (WLP). The key processes, including cavity wall (CW) dam formation through non-photosensitive film vias development using a laser drilling process, a redistribution layer (RDL), and ball-grid array formation are developed. In addition, a numerical study based on the finite element model has been conducted to analyze the stress distribution of Cu RDL traces. In addition, the CW dam and the roof layer are covered with polymer, which solves the delamination problem between the CW dam and the substrate. Meanwhile, after practical verification, the SAW filter WLP was resistant to encapsulating pressure using a high elastic modulus capping material, which solved the collapse problem. Additionally, a comparison of the RF filter package’s electrical performance following the preconditional level 3 and unbiased highly accelerated stress test revealed no differences in insertion attenuation across the passband (<0.2 dB, standard value: 1 dB). The final packages passed the reliability tests in the field of consumer electronics.

A new on-line ultrasonic thickness monitoring system for high temperature pipes

On-line thickness monitoring of pipe wall is very important in petrochemical and power generation industries. There are two main reasons that the conventional ultrasonic transducers cannot withstand long-term on-line monitoring in high temperature. One is that the piezoelectric elements within transducers depolarize causes them to fail, the other is that the working medium inside the pipeline interferes with the ultrasonic wave results in the decline of measurement accuracy. In order to overcome these problems, an ultrasonic thickness gauge using a waveguide that can sustain a large temperature drop and effectively transmit the quasi-fundamental shear horizontal (SH0*) wave without causing dispersion is designed. The waveguide can isolate the vulnerable piezoelectric sensor from the high-temperature measurement zone, and the SH0* wave can avoid interfere of the working medium. Moreover, a monitoring system applying this ultrasonic thickness gauge is discussed and the application method of this system is introduced. The high temperature long-term reliability experiments carried out both in laboratory and on-site, and wall thinning measurement by corrosion experiments show that the designed thickness gauge has good accuracy and long-term stability, which can meet the needs of long-term on-line monitoring of high temperature pipes.

Operando Imaging of Ce Radical Scavengers in a Practical Polymer Electrolyte Fuel Cell by 3D Fluorescence CT-XAFS and Depth-Profiling Nano-XAFS-SEM/EDS Techniques.

There is little information on the spatial distribution, migration, and valence of Ce species doped as an efficient radical scavenger in a practical polymer electrolyte fuel cell (PEFC) for commercial fuel cell vehicles (FCVs) closely related to a severe reliability issue for long-term PEFC operation. An in situ three-dimensional fluorescence computed tomography-X-ray absorption fine structure (CT-XAFS) imaging technique and an in situ same-view nano-XAFS-scanning electron microscopy (SEM)/energy-dispersive spectrometry (EDS) combination technique were applied for the first time to perform operando spatial visualization and depth-profiling analysis of Ce radical scavengers in a practical PEFC of Toyota MIRAI FCV under PEFC operating conditions. Using these in situ techniques, we successfully visualized and analyzed the domain, density, valence, and migration of Ce scavengers that were heterogeneously distributed in the components of PEFC, such as anode microporous layer, anode catalyst layer, polymer electrolyte membrane (PEM), cathode catalyst layer, and cathode microporous layer. The average Ce valence states in the whole PEFC and PEM were 3.9+ and 3.4+, respectively, and the Ce3+/Ce4+ ratios in the PEM under H2 (anode)-N2 (cathode) at an open-circuit voltage (OCV), H2-air at 0.2 A cm-2, and H2-air at 0.0 A cm-2 were 70 ± 5:30 ± 5%, as estimated by both in situ fluorescence CT-X-ray absorption near-edge spectroscopy (XANES) and nano-XANES-SEM/EDS techniques. The Ce3+ migration rates in the electrolyte membrane toward the anode and cathode electrodes ranged from 0.3 to 3.8 μm h-1, depending on the PEFC operating conditions. Faster Ce3+ migration was not observed with voltage transient response processes by highly time-resolved (100 ms) and spatially resolved (200 nm) nano-XANES imaging. Ce3+ ions were suggested to be coordinated with both Nafion sulfonate (Nfsul) groups and water to form [Ce(Nfsul)x(H2O)y]3+. The Ce migration behavior may also be affected by the spatial density of Ce, interactions of Ce with Nafion, thickness and states of the PEM, and H2O convection, in addition to the PEFC operating conditions. The unprecedented operando imaging of Ce radical scavengers in the practical PEFCs by both in situ three-dimensional (3D) fluorescence CT-XAFS imaging and in situ depth-profiling nano-XAFS-SEM/EDS techniques yields intriguing insights into the spatial distribution, chemical states, and behavior of Ce scavengers under the working conditions for the development of next-generation PEFCs with high long-term reliability and durability.

A Study of Transient Liquid Phase Bonding Using an Ag-Sn3.0Ag0.5Cu Hybrid Solder Paste

The feasibility of transient liquid phase (TLP) bonding technology for high-temperature endurable power electronics packaging has been evaluated in this study. An Ag-Sn3.0Ag0.5Cu hybrid solder paste was fabricated and used as a bonding material. The bonding reactions between chip/substrate and hybrid solder paste and die shear strengths of the TLP-bonded joints were evaluated during conventional soldering and vacuum soldering processes. Compared to the conventional soldering, the vacuum-soldered joints had fewer voids and relatively good metallurgical microstructures. After TLP bonding, (Cu,Ni)6Sn5, Ag3Sn, and Cu6Sn5 intermetallic compounds formed at the chip interface, in the middle of the joint, and at the bottom interface, respectively. It was confirmed that the vacuum soldering process could create good interfacial uniformity with minimal voids in the Si chip/ceramic substrate joints. The formation of voids during TLP bonding significantly affected the mechanical shear strength of the TLP-bonded joints. The vacuum-soldered joints had high shear strength values of approximately 40 MPa. To ensure the high joint strength and long-term reliability of Sn-based TLP-bonded joints, critical void control in the joints is needed.

Computational modeling of thermal characteristics of hybrid nanofluid in micro-pin fin heat sink for electronic cooling

ABSTRACT Emerging technology in the electronic industry has led to miniaturization of electronic devices such as iPhones and laptops. Heat dissipation is required to maintain high performance and long-term reliability of these devices. Micro heat sinks and novel working fluids such as nanofluids are becoming popular. Until recent times the full potential of hybrid nanofluid in heat transfer has not yet been exploited. In order to address the lack of adequate modeling data in this field, the aim of this study is to systematically model and investigate computational heat transfer characteristics of Al2O3-Cu/water hybrid nanofluid in micro heat sink. Volume concentration in the range of 0.1%-0.5% was used for the working fluid. Hexagonal micro-pin fin heat sink with staggered arrangement was simulated in ANSYS Fluent. Reliable experimental result from literature was used to validate the accuracy of the results. The most obvious finding to emerge from this study is that the Nusselt number increases with increase in Reynolds number and this observation is consistently the same at different concentrations and pin spacing. Lower transverse pitch was observed to dominate the enhancement of Nusselt number. There was a 10% increase in heat transfer coefficient at 0.5% nanofluid concentration when compared to 0.1%. This phenomenon is highly influenced by the transition of the Re into turbulent situation which eventually enhances the heat transfer characteristics. Also, lower transverse pitch promotes swirling flow situation. At 0.5% hybrid nanofluid concentration, it was observed that the Nusselt number increased from 14.00 at transverse pitch of 3.81 mm to 17.00 at a transverse pitch of 1.81 mm and this corresponds to 16.05% enhancement of Nusselt number. The pressure drop penalty of the working fluid is a result of increase in viscous effect of the hybrid nanofluid, especially at high concentration.

Environmental-friendly electrospun phase change fiber with exceptional thermal energy storage performance

Electrospun phase change fiber (PCF) releases more than 85 wt% of organic solvents yet suffers from long-term thermal cycling-induced leakage. In this contribution, a novel PEG/PVA composite PCF was obtained by electrospinning their aqueous solution instead of using organic solvent in traditional method, which makes design of PCF towards green and cost-effective direction. Meanwhile, a simple surface crosslinking technology was applied to prevent leakage of PEG during the long-term service, and improve the thermal stability and tensile strength of the obtained crosslinked PCF (CPCF). The CPCF-50 shows the optimal morphological structure and exhibits the a relative high latent heat of 72.3 J/g. Owing to the confinement effect, CPCF exhibits robust thermal, chemical, and morphological stability with respect to 1000 thermal cycling. The CPCF also shows exceptional temperature regulation capability. The thermoregualting times of heating and freezing processes of CPCF-50 are 59.0% and 89.5% longer than those of the control and CPCF-0, respectively. Therefore, the eco-friendly and cost-effective prepared CPCF in this work, which exhibits relatively high latent heat and long-term reliability, paves a new way for the large-scale production of phase change fiber for thermal energy storage application.

Time and Area Optimized Testing of Automotive ICs

As cars become increasingly computerized and their safety functions evolve rapidly, the number of complex safety-critical components deployed in advanced driver assistance systems or autonomous vehicles is rising dramatically with high-end models containing hundreds of embedded microcontrollers. These integrated circuits must adhere to stringent requirements for high quality and long-term reliability driven by functional safety standards. This requires test solutions that address challenges posed by automotive systems. This article presents a scan-based test scheme optimizing test time and area overhead during manufacturing and in-system test of automotive electronics. The proposed scheme deploys observation test points that capture the faulty effects in every shift cycle into separate observation scan chains. To reduce area overhead, the scheme enables the sharing of flip-flops among control points. It is also shown how test points enhance test coverage (TC) in the presence of cascaded clock gaters. Finally, processing challenges when fault simulating every scan shift cycle to determine TC are addressed. Experimental results obtained for contemporary automotive designs and reported herein show significant improvements in test quality over traditional solutions.

Study of Warpage Evolution and Control for Six-Side Molded WLCSP in Different Packaging Processes

A six-side molded wafer-level chip scale package (mWLCSP) is a novel and attractive packaging method for smart phone applications due to its lower cost, better electrical performance, and higher long-term reliability. Nevertheless, wafer warpage in different manufacturing processes is a significant issue for the six-side mWLCSP. This article focuses on wafer warpage evolution in different packaging processes and the development of control method for the six-side mWLCSP. A quarter wafer-level finite-element (FE) model and a strip-level FE model were established to simulate the actual packaging processes by element birth and death method and restart technology. Both the FE models were proved quite efficient and accurate for warpage prediction compared to the experimental results. The effects of geometric parameters and material parameters on the maximum warpage value were studied based on the two established FE warpage models, and some recommendations were given for warpage optimization. Based on the above studies, an improved manufacturing process flow for the six-side mWLCSP was presented and proved feasible to control the maximum warpage value under 3 mm. It offers an insight work for the development and warpage control of the six-side mWLCSP and other wafer-level molded packages.

A Method for Improving the Thermal Shock Fatigue Failure Resistance of IGBT Modules

High temperature application and long-term reliability are the future development trends of IGBT (insulated gate bipolar transistor) module. This article proposes a 1200-V/50-A IGBT module using the current-assisted sintered nanosilver as die attachment and high-temperature solder as substrate attachment. We measured and compared the electrical and the thermal characteristics, and the reliability of the proposed IGBT modules with those of the commercial IGBT module of the same level. The proposed IGBT modules show consistency with commercial IGBT module in electrical performance, which also proved the feasibility of the current-assisted sintering. The thermal impedance of the proposed IGBT module decreased by 17.2% compared with that of the commercial one. And, the thermal shock test shows that higher resistance to thermomechanical fatigue can be successfully achieved.

Development of a Long Autologous Small-Caliber Biotube Vascular Graft

Introduction - Small-caliber synthetic vascular grafts (<6 mm) with acceptable patency for coronary bypass or peripheral vascular repair below the knee are very rare. We have developed an autologous small-caliber vascular graft, Biotube, using the simple, safe, and economical in-body tissue architecture technology, which is a novel concept in regenerative medicine. Biotubes have shown good performance as aortic grafts for almost 10 years in a canine model. Recently, first-in-human study of Biotube was successfully performed for hemodialysis access. This study presents the preparation of long Biotube over 20 cm. Its in vivo performance was evaluated in an animal implantation model. Methods - For the preparation of the long Biotube spiral plastic mold was designed. The mold had spiral center rod (diameter 4 mm, length 25 mm) covered with a slitted tubular cage (clearance: 1 mm). Upon 2-month embedding into subcutaneous pouches of beagles autologous connective tissue was ingrown inside the cage through the slits and completely fulfill the clearance between the rod and the cage to form tubular connective tissue. Results - Completely autologous tissue Biotubes with diameter of 4 mm, length of over 20 cm and wall thickness of 1 mm were autonomically formed in the subcutaneous space and obtained by removing all parts after harvesting of the molds. Since their wall tissues were very flexible and robust, original spiral shape was easily regulated in desire. The Biotubes were implanted to canine carotid arteries by end-to-end anastomoses in loop shape with high performance. Conclusion - The Biotube showed excellent vascular performance, and can be considered useful in several vascular conditions with high long-term reliability.

Super soft but strong E-Skin based on carbon fiber/carbon black/silicone composite: Truly mimicking tactile sensing and mechanical behavior of human skin

Besides the prominent tactile sensing ability, human skin is also well known for its unique mechanical behavior – combination of excellent softness with certain stretchability of a strain-limiting effect to prevent damage from excessive strain. Here a stretchable e-skin truly mimicking the tactile sensing and mechanical behavior of human skin is fabricated. Carbon black (CB)/silicone composite with excellent piezo-resistive performance is employed as mechanical stimuli sensing material, which provides super softness, large stretchability, high strain sensitivity and long-term reliability for the e-skin. High performance carbon fiber (CF) with quasi-sinusoidal shape is designed to serve as electrode material and reinforcement filler simultaneously, which renders the e-skin a typical J-shape stress-strain curve similar as that of human skin. The Young's modulus, tensile strength and failure strain of the e-skin can be readily adjusted by controlling the content and shape of the CF electrode to match them well with those of human skin. Finally, the fabricated e-skin exhibits the capability of spatiotemporal recognition of the location and magnitude of contact forces in monitoring dynamic stress distribution. The as-prepared stretchable e-skin based on CF/CB/silicone composite is highly promising for robotics and prosthetics, etc.

Deterministic Stellar BIST for Automotive ICs

As the automotive industry enters a period of rapid evolution changing the way cars are designed and produced, the number of complex safety-critical components deployed in advanced driver assistance systems or autonomous vehicles is progressively rising with high-end models containing around 120 MCUs. These integrated circuits must adhere to stringent requirements for high quality and long-term reliability driven by functional safety standards. This requires test solutions that address challenges posed by automotive electronics. This paper presents Stellar BIST—a next generation compression scheme for in-system automotive test. The proposed solution can work with any sequential test compression. It builds on a finding that certain clusters of test vectors are capable of detecting many random-resistant faults, where a cluster consists of a parent (base) pattern and its transformed derivatives. Stellar BIST involves generating vectors based on simultaneous and multiple complements of scan slices of encodable parent patterns. The multiple complements are also skewed between successive patterns to diversify the resultant tests. The new scheme elevates compression to values unachievable through conventional reseeding-based solutions and provides significant tradeoffs between storage requirements and test application time, critical for in-system automotive applications. The experimental results obtained for industrial designs and different fault models illustrate feasibility of the proposed test scheme and are reported herein.

Low Power and Low Noise Shift Register for In-Cell Touch Display Applications

This paper proposes a shift register circuit integrated in in-cell touch display panels that achieves low power operation, low coupling noise, and high long-term reliability with 11 thin film transistors (TFTs) and two capacitors. A time division driving method is utilized to prevent the crosstalk of display signals into touch circuits, and two pre-charging nodes are employed to relieve the uniformity degradation of output signals caused by different stresses on pull-up TFTs. The proposed circuit activates a drain of the first pre-charging TFT only at display scanning periods, which reduces coupling noises and power consumption. In addition, an internal inverter is turned off for touch sensing operations, resulting in a wide range of threshold voltage shift compensation and low power consumption. SPICE simulation results with a low temperature poly silicon TFT model show that the proposed circuit compensates for the threshold voltage shift up to 17 V. In a 60 Hz full-HD display with a 120 Hz touch reporting rate, the noise level of the first pre-charging node is −16.78 dB in between 2.37 and −28.95 dB of two previous circuits, and the total power consumption for 160 stages is substantially reduced to 4.44 mW compared to previous approaches.

Energy and Lifetime Optimizations for Dark Silicon Manycore Microprocessor Considering Both Hard and Soft Errors

In this paper, we propose a new energy and lifetime optimization techniques for emerging dark silicon manycore microprocessors considering both hard long-term reliability effects (hard errors) and transient soft errors, which have been studied less in the past. We consider a recently proposed physics-based electromigration (EM) reliability model to predict the EM-induced reliability. We employ both dynamic voltage and frequency scaling (DVFS) and dark silicon core state using ON/OFF switching action as the two control knobs. We show that on-chip power consumption has different (even contradicting) impacts on soft and hard reliability effects. This paper also shows that soft error should be mitigated by other techniques if aggressive low power and high long-term reliability are pursued. We focus on two optimization techniques for improving lifetime and reducing energy. To optimize EM-induced lifetime, we first apply the adaptive Q-learning-based method, which is suitable for dynamic runtime operation as it can provide cost-effective yet good solutions. The second lifetime optimization approach is the mixed-integer linear programming (MILP) method, which typically yields better solutions but at higher computational costs. To optimize the energy of a dark silicon chip subject to the both hard and soft reliability effects, power budgets, and performance limits, the Q-learning method has been applied as well. A large class of multithreaded applications is used as our benchmarks to validate and compare the proposed dynamic reliability management methods. Experimental results on a 64-core dark silicon chip show that the proposed DRM algorithm can effectively manage and optimize the lifetime of a dark silicon microprocessor under the given power budget and performance limit. Also, the proposed energy optimization can effectively manage and optimize energy consumption subject to both hard and soft-error rates, power budget, and performance limits as constraints. We also show that the under tightened power and performance constraints, we cannot satisfy both hard and soft errors at the same time as there is no simple tradeoff between performance/power and reliability in this case. Some other soft-error mitigation techniques are required in this case.

Pore structure modified diatomite-supported PEG composites for thermal energy storage.

A series of novel composite phase change materials (PCMs) were tailored by blending PEG and five kinds of diatomite via a vacuum impregnation method. To enlarge its pore size and specific surface area, different modification approaches including calcination, acid treatment, alkali leaching and nano-silica decoration on the microstructure of diatomite were outlined. Among them, 8 min of 5 wt% NaOH dissolution at 70 °C has been proven to be the most effective and facile. While PEG melted during phase transformation, the maximum load of PEG could reach 70 wt.%, which was 46% higher than that of the raw diatomite. The apparent activation energy of PEG in the composite was 1031.85 kJ·mol−1, which was twice higher than that of the pristine PEG. Moreover, using the nano-silica decorated diatomite as carrier, the maximum PEG load was 66 wt%. The composite PCM was stable in terms of thermal and chemical manners even after 200 cycles of melting and freezing. All results indicated that the obtained composite PCMs were promising candidate materials for building applications due to its large latent heat, suitable phase change temperature, excellent chemical compatibility, improved supercooling extent, high thermal stability and long-term reliability.

A high transmittance optical recording material with long-term reliability for super-multilayer discs

As a means of increasing data capacity, the multilayer optical disc is a promising approach. Because the recording layers in multilayer optical discs must have a high transmittance, they are commonly made of transparent oxide films. Moreover, the recording layer must have sufficient long-term reliability for data archival. In this work, a recording material with high transmittance and long-term reliability for use in super-multilayer discs was investigated. This paper clarifies the recording mechanism of GeBi oxide material and proposes a suitable material design that satisfies the abovementioned characteristics. Furthermore, experimental results of recording on super-multilayer discs based on GeBi oxide recording material are presented.