Electronic Packaging Industry Research Articles

Finite element analysis and experimental study on the cutting mechanism of SiCp/Al composite in laser ultrasonic elliptic vibration turning

SiCp/Al composites have excellent material properties and are increasingly being used in the aerospace, military, and electronic packaging industries. However, the inhomogeneity and non-conductivity of conventional turning (CT) results in poor material surface quality and high cutting forces, which seriously hinder the application of particlereinforced metal matrix composites. The thermal softening property of laser-assisted turning (LAT) and the intermittent cutting property of two-dimensional (2D) ultrasonic elliptical vibratory turning (UEVT) offer unique advantages in improving material surface quality. Therefore, a novel laser ultrasonic elliptical vibratory turning (LUEVT) machining technique is proposed to improve the machining of SiCp/Al composites with two different volume fractions. The effect of highfrequency intermittent machining on material processing was further investigated by adjusting the pulsed laser power. Finite element modelling was used to predict the machining state, surface roughness, and chip morphology between the workpiece and the PCD tool. The effects of varying the machining parameters during the experiment on the two composites were analysed. The results showed that the LUEVT of 25 % and 45 % SiCp/Al composites were reduced by 39.3 % and 30.7 % respectively compared to the CT cutting forces. The experiments verified the consistency of the surface roughness and chip morphology with the finite element simulation results. The stability of the cutting force during the cutting process is also improved, as the material removal process mainly takes the form of small particle fragmentation and matrix encapsulation.

Microstructure, joining mechanism, mechanical properties and optimization of inactive solder (Sn9Zn) in low temperature ultrasonic soldering of AlN ceramics and 2024Al

With the development of the electronic packaging industry, there is an increased demand for enhanced strength in DBA substrates. Ultrasonic soldering technology allows low-temperature joining of ceramic-metal materials under ambient air conditions. In this paper, we successfully achieved the joining between AlN ceramics and 2024Al using Sn9Zn solder and ultrasonic soldering technique, while also analyzing the joining mechanism through Comsol software simulations. It was observed that under the appropriate ultrasonic amplitude and frequency, the Sn9Zn solder exhibited complete wetting with both base materials, resulting in reliable joints. Building upon this finding, the conventional Sn9Zn solder was further optimized by adding Sb element. The addition of Sb element led to the formation of Zn4Sb3 phase and β-Sn(Sb) phase with Sb acting as solute. Among them, the generation of β-Sn(Sb) solid solution phase effectively improved the joint strength. The maximum joint strength was achieved at an average value of 75.066 MPa when the Sb content reached 1 wt. %. At this point, the failure occurred within the AlN ceramic base material.

Effects of TiC nanoparticle addition on microstructures and mechanical properties of Sn-58Bi solder joints

The Sn58Bi solder has gained significant attention in the electronic packaging industry owing to its low melting temperature and excellent mechanical properties. However, the brittleness of Sn58Bi solder presents challenges in practical applications. This study investigates the effect of adding titanium carbide (TiC) nanoparticles on the mechanical properties of Sn58Bi solder joints. The study examines the melting behavior, spreadability, microstructure, and mechanical properties of Sn58Bi-xTiC (x = 0, 0.05, 0.1, 0.2 wt%) composite solders. The results indicate that adding TiC nanoparticles has merely a minor effect on the melting point of the Sn58Bi solder. However, the presence of TiC nanoparticles refined the solder’s microstructure, reduced the thickness of the intermetallic compounds, and enhanced the spreadability and mechanical properties. The Sn58Bi-0.1TiC composite solder exhibits the most favorable properties, including a 28.6 % increase in fracture energy compared with that of Sn58Bi solder. Consequently, incorporating TiC nanoparticles enhances the performance of the Sn58Bi solder by improving its spreadability and reducing its brittleness. These results hold great potential for advancing the development of lead-free solders with improved reliability and performance in electronic applications. The findings of this study could pave the way for the practical and widespread use of Sn58Bi-xTiC composite solders, offering a viable alternative to lead-containing solders while maintaining excellent mechanical characteristics.

Continuous composite longitudinal fins under oscillating boundary conditions: a lattice Boltzmann solution

PurposeTransient response of continuous composite material (CCM) fin made of high thermally conductive composite material is presented. The continuously varying effective properties of composite material such as thermal conductivity, heat capacity and density have been modelled using the Mori-Tanaka homogenization theory and rule of mixture. Additionally, temperature dependency of thermal conductivity, heat generation (composite materials) and convection coefficient (fluid properties) have also been incorporated. Different base boundary conditions are addressed such as oscillating heat flow, oscillating temperature, step-changing heat flow and step-changing temperature. At the other boundary, the fin is assumed to have a convective tip.Design/methodology/approachLattice Boltzmann method is implemented using an in-house source code for obtaining the numerical solution of typical non-linear heat balance equation of the aforementioned problem under various transient base boundary conditions.FindingsThe effects of various thermal parameters such as material diffusivity ratio and conductivity ratio, area ratio and Biot number on transient response of fin and temperature distribution of fins are studied and interpreted. The heat transfer rate and time for attainment of steady state temperature of metal matrix composite (MMC) fin are found to be proportionally dependent on their diffusivity ratio. Additionally for higher values of area ratio and biot number, MMC fins are reported to dissipate the heat more efficiently in comparision to homogeneous fins in terms of time required to attain the steady state and surface temperature.Practical implicationsResponse of transient fin associated with advanced class of material can facilitates the practicing engineers for designing high-performance and/or miniaturized thermal management devices as used in electronic packaging industries.Originality/valueStudies of composite fin consisting of laminating second layer of material over the first layer have been reported previously, however transient response of CCM fin fabricated by continuously varying the volume fraction of two materials along the fin length has not been reported till date. Such material finds its application in thermal management and electronic packaging industries. Results are plotted in form of a graph for different application-wise material combinations that have not been reported earlier, and it can be treated as design data.

Effect of Silicone Rubber on the Properties of Epoxy/Recovered Carbon Black (rCB) Conductive Materials

The primary focus of this study is to investigate the effect of silicone rubber (SR) content on the mechanical, thermal, electrical conductivity, and morphological properties of epoxy/recovered carbon black (rCB) conductive material. The conductive material is used to produce the electrostatic discharge (ESD) tray for the electronic packaging industry. This study investigated the effect of silicone rubber content (0, 5, 10, 15, and 20 vol.%) on the properties of epoxy/SR/rCB conductive materials, with the rCB content fixed at 15 vol.% for its optimum electrical conductivity. The silicone rubber acts as a toughening agent for epoxy. Through the fracture toughness result, it can be identified that silicone rubber plays a role in improving the toughness properties of the epoxy/SR/rCB conductive material. The optimum results for mechanical properties were recorded at 5 vol.% SR. The addition of SR to the epoxy matrix enhances the electrical properties of the epoxy/SR/rCB conductive material. The effect of thermal aging on epoxy/SR/rCB conductive materials was also studied to determine the properties of the conductive material materials at high temperatures for a long period of time. After thermal aging, the mechanical, thermal, electrical conductivity, and morphological properties of the epoxy/SR/rCB conductive material were slightly reduced.

Influence of doping Si3N4 nanoparticles on the properties and microstructure of Sn58Bi solder for connecting Cu substrate

Purpose This study aims to explore the feasibility of adding Si3N4 nanoparticles to Sn58Bi and provides a theoretical basis for designing and applying new lead-free solder materials for the electronic packaging industry. Design/methodology/approach In this paper, Sn58Bi-xSi3N4 (x = 0, 0.2, 0.4, 0.6, 0.8, 1.0 Wt.%) was prepared for bonding Cu substrate, and the changes in thermal properties, wettability, microstructure, interfacial intermetallic compound and mechanical properties of the composite solder were systematically studied. Findings The experiment results demonstrate that including Si3N4 nanoparticles does not significantly impact the melting point of Sn58Bi solder, and the undercooling degree of solder only fluctuates slightly. The molten solder spreading area reached a maximum of 96.17 mm2, raised by 19.41% relative to those without Si3N4, and the wetting angle was the smallest at 0.6 Wt.% of Si3N4, with a minimum value of 8.35°. When the Si3N4 nanoparticles reach 0.6 Wt.%, the solder joint microstructure is significantly refined. Appropriately adding Si3N4 nanoparticles will slightly increase the solder alloy hardness. When the concentration of Si3N4 reaches 0.6 Wt.%, the joints shear strength reached 45.30 MPa, representing a 49.85% increase compared to those without additives. A thorough examination indicates that legitimately incorporating Si3N4 nanoparticles into Sn58Bi solder can enhance its synthetical performance, and 0.6 Wt.% is the best addition amount in our test setting. Originality/value In this paper, Si3N4 nanoparticles were incorporated into Sn58Bi solder, and the effects of different contents of Si3N4 nanoparticles on Sn58Bi solder were investigated from various aspects.

Effect of Hexagonal Boron Nitride on Morphology, crystallinity and internal Exfoliation properties of Polypropylene melt and solid phases

ABSTRACT Polypropylene (PP) is one of the most important polymers widely used in different industries due to its many superior properties. Hexagonal boron nitride (hBN) is generally used in the electronic packaging industry and insulator material production due to its high thermal conductivity and low electrical conductivity. However, the lubrication properties have not yet been examined in the polymer matrix. The main purpose of this study is to examine the lubricating properties of hBN in the PP matrix and to expand its application areas. In this research, hBN/PP composites have been produced and characterized by scanning electron microscopy with an energy dispersive X-ray detector (SEM-EDX) and the differential scanning calorimeter (DSC), respectively. The linear viscoelastic behaviors (LVBs) and rheological properties of the hBN/PP composites have been investigated at 190°C by hybrid rheometer which had high temperature plate-plate geometry system; furthermore, the SEM has been used for searching hBN particles deformation, which was mechanical deformation and distribution into the PP. The oscillation sweeps tests have shown that the critical strain values and the gelation point of composites decreased with the increasing of the hBN content into the composites. Over the 10%, hBN addition into the PP elevated internal lubrication by the exfoliation of hBN plaques. The Williamson model and the discrete retardation spectrum (DRS) equation has been applied on the hBN loaded PP composites and the PP.

Research on Adhesive Quality Control Based on Piezoelectric Dispensing Valve

Non-contact dispensing in the electronics packaging industry is becoming the most widespread dispensing method. The crucial research direction is to achieve accurate flow control for non-contact dispensing technology. However, the whole dispensing process contains fluid-solid coupling and its nonlinear and unstable flow, which makes it difficult to obtain an accurate prediction model for the quality of adhesive points. In this paper, based on the existing theory and the idea of minimum error backpropagation, we compare the experimental data with the theoretical value of adhesive point by subsequent experiments. Finally, a simple and effective adhesive point quality prediction model for non-Newtonian fluids in the dispensing process is obtained. The Taguchi method was used to prove that the maximum error between the predicted adhesive point quality and the experimental value is <10%, which is highly accurate. The Minitab software was used to analyze Taguchi's experimental data, and the sensitivity of dispensing quality to process parameters was ranked as follows: driving voltage > adhesive supply pressure > nozzle heating temperature; this study can be of guidance to the design of dispensing valve structure and dispensing process parameters, and to achieve high speed and high precision flow control.

3D CT scan metrology for solder void formation analysis in ball grid array electronic chips

The miniaturization of silicon chips and the complexity of device functionality has driven the electronic packaging industry to find new methods to enhance the reliability of chips at a smaller size. Solutions such as Ball Grid Array (BGA) packages have contributed to the miniaturization of integrated circuits (ICs) and the reduction in their overall size. However, void formation in the solder joint is a weakness that can affect the robustness of the solder joint integrity, both mechanically and electrically. To detect these voids, metrology methods such as 3D Computed tomography (CT)-scan are used. 3D CT-scans can identify submicron-sized void defects in real-time during thermal tests, which can be utilized to help improve the quality control lines in the electronic chip manufacturing industries. In this paper, two types of BGA packages will be evaluated for solder joint properties. The prepared samples will be subject to high temperature stress conditions to assess the mechanism of void formation in solder joint. The prepared samples will be heated at 260 °C four times where the heating lasts 0, 5, 10, and 15 min, respectively. The prepared samples will be mounted on a PCB board and the results of the thermal stress tests will be analyzed using 3D X-ray CT scans. These 3D-CT scans used in tandem with a reconstruction and visualization software suite, will be utilized to observe changes such as void formation in the solder joint after each heating time. Unexpectedly, void size reduced between the first and second heat cycles on both samples but increased for the third and fourth heat cycles then.

Novel functionalized isocyanate groups polyhedral oligomeric silsesquioxanes/epoxy composites with advanced thermal and moisture resistance properties

AbstractThe rapid development of the electronic packaging industry has necessitated the production of epoxy resin insulation materials with high heat resistance and low water absorption. In this study a new cross‐linking composite composed of polyhedral oligomeric silsesquioxane (POSS) functionalized with isocyanate groups and epoxy resin (EP) containing phenolic hydroxyl groups. By employing an isocyanate‐hydroxyl process, the cage structure of Ph7POSS with isocyanate functionalization (MP) can be suspended on EP, leading to a significant improvement in the thermal and moisture resistance of the MP/EP composite. Our DSC and TGA studies revealed that the addition of 3% MP to the epoxy resin increased the glass transition temperature by 27.1°C and raised the initial thermal breakdown temperature to 334.5°C. We also utilized a novel quartz crystal microbalance (QCM) technique to continuously monitor the moisture resistance of the composite, and our results showed that the composite absorbed only 0.03% of water. Moreover, the porosity and cross‐linking of the POSS molecules further restricted the movement of the polymer chains, thereby reducing the dielectric constant and dielectric loss of the composite. Consequently, the MP‐modified epoxy composites exhibit excellent properties, which suggest promising applications in the field of electronic packaging.

Kinetics of Cu6Sn5 and Cu3Sn intermetallic compounds growth and isothermal solidification during Cu-Sn transient liquid phase sintering process

The kinetics of Cu-Sn intermetallic compounds (IMCs) growth relates to the materials preparation, process regulation and reliability prediction in the new energy field and electronic packaging industry. As a typical instance that Cu-Sn IMCs are involved with, this work investigated the kinetics of Cu-Sn IMCs growth and isothermal solidification of Cu-Sn transient liquid phase sintering (TLPS) process for high temperature resistant packaging of the third-generation semiconductors power devices. A three-dimensional kinetics model of Cu/Sn solid/liquid interfacial reaction and the corresponding kinetics equations of Cu6Sn5 and Cu3Sn growth was established. Based on Cu-Sn IMCs growth kinetics, a parameter ξSn called the residual rate of Sn was defined to characterize the isothermal solidification kinetics of Cu-Sn TLPS process. By measuring the volume fraction of Cu and Sn, the quality fraction of residual Cu and Sn and produced Cu-Sn IMCs were determined, and thus the kinetics of Cu-Sn IMCs growth and the isothermal solidification of Cu-Sn TLPS process were experimentally studied to validate the theoretical model. The results showed that the theoretical results predicted by the model were well-matched with experimental results. Besides rising temperature, the kinetics of Cu-Sn IMCs growth and the isothermal solidification can be remarkably accelerated by decreasing Cu particle size. Reducing Sn content does not affect the kinetics of Cu-Sn IMCs growth but helps to shorten the isothermal solidification time of Cu-Sn TLPS process.

Design and experiment of a new double needle type piezoelectric jetting dispenser

To improve the performance of piezoelectric (PZT) jetting dispensers in the electronic packaging industry and address the problems of oversized, easily fatigued elastic hinges and low repetition accuracy of conventional PZT jetting dispensers with a compliant mechanism-based lever, a new double needle PZT jetting dispenser prototype was developed. The advantage of the proposed structure over compliant mechanism-based lever was demonstrated by dynamics analysis. Firstly, the design stroke of the needle and the modal state of the dispenser body were analyzed using ANSYS. Secondly, the theoretical model of adhesive injection was established, the fluid pressure change process inside the nozzle during the working cycle of the jetting dispenser was simulated using Fluent, and the effects of the supply pressure and needle stroke on the injection speed of the droplet were investigated. Finally, a test bench was built to conduct the experiment, and the results showed that the supply pressure and the driving signal duty cycle between 20% and 80% were positively correlated with the size of droplet diameter, whereas the driving signal frequency was negatively correlated with the droplet diameter, thereby validating the proposed adhesive injection model. Under the experimental conditions, the highest operating frequency of the designed PZT jetting dispenser was 400 Hz, which is close to the high-frequency level of existing studies, and the minimum droplet diameter obtained was 0.36 mm, which is 0.1–0.2 mm less than that of the existing PZT jetting dispenser with a compliant mechanism drive, meeting the industry requirements for the working performance of a PZT jetting dispenser.

Metallographic Mechanism of Embrittlement of 15 μm Ultrafine Quaternary Silver Alloy Bonding Wire in Chloride Ions Environment.

Chloride ions contained in the sealing compound currently used in the electronic packaging industry not only interact with intermetallic compounds but also have a serious impact on silver alloy wires. A 15 μm ultrafine quaternary silver-palladium-gold-platinum alloy wire was used in this study. The wire and its bonding were immersed in a 60 °C saturated sodium chloride solution (chlorination experiment), and the strength and elongation before and after chlorination were measured. Finally, the fracture surface and cross-section characteristics were observed using a scanning electron microscope and focused ion microscope. The results revealed that chloride ions invade the wire along the grain boundary, and chlorides have been generated inside the cracks to weaken the strength and elongation of the wire. In addition, chloride ions invade the interface of the wire bonding to erode the aluminum substrate after immersing it for enough long time, causing galvanic corrosion, which in turn causes the bonding joint to separate from the aluminum substrate.

Three-dimensional network of hexagonal boron nitride filled with polydimethylsiloxane with high thermal conductivity and good insulating properties for thermal management applications

Electronic components tend to fail due to heat accumulation during use. As a result, thermally conductive and insulating polymer-matrix composites (PMCs) are in great demand in the electronics packaging industry. This study proposes a new hard-template approach for the construction of a three-dimensional hexagonal boron nitride foam (3D-BN) using PMMA microspheres as sacrificial materials. The 3D-BN is then filled with polydimethylsiloxane (PDMS) to create 3D-BN/PDMS composites with high thermally conductivities and good insulating properties. The results of various characterization analyses and 3D finite element simulation show that the 3D-BN is the fundamental factor in improving the thermal conductivity (TC) of the composites. Compared with nanoscale h-BN (nBN), micron h-BN (mBN) is more organized along the pore walls in 3D-BN, better utilizing the in-plane TC of h-BN while reducing the interface thermal resistance (ITR). The obtained lightweight composite exhibits a high TC of 1.868 Wm−1K−1 and an ultrahigh volume electrical resistivity of 3.66 × 1013 Ω m at 18.33 vol% mBN loading. This research provides a promising strategy for designing and fabricating thermal management PMCs.

A New Two-Phase Multiplier for Flow Pressure Drop in Multiport Minichannel Condensers and Evaporators

Due to flow maldistribution, the condensation and evaporation flow patterns in multiport minichannels are considerably different from single minichannels or macrochannels. This article compiled the friction pressure drop data from experimental phase-change investigations in multiport minichannel condensers and evaporators over the past two decades. The data was reduced to friction pressure gradients, and a new two-phase multiplier was proposed for estimating the phase-change pressure drop in multiport condensers and evaporators. Thirteen hundred and forty-four condensation pressure drop and six hundred and twenty-three evaporation pressure drop data from twenty-nine studies were correlated to yield four predictive two-phase multiplier equations in the laminar and turbulent flow regimes. The predictive correlations fit 67% of the laminar condensation and 80% of the turbulent pressure drop data within ±50%. Further, 57% of the laminar evaporation and 100% of the turbulent evaporation pressure drop data were fit within ±50%. The correlations were compared with widely published correlations and were a significant improvement. Meta-analysis revealed that multiport minichannels are most effective for reducing turbulent flow condensation pressure drop and laminar flow evaporation pressure drop. The compiled data and presented correlations and analysis should be helpful to the process, electronics packaging, aviation, and aerospace industries designing compact, lightweight, and high-efficiency condensers, and evaporators.

Magnetron Sputtering Deposition of Lead-Free (SAC) Thin-Film Alloys and Mechanical Characterization Using Nanoindentation

Electronic packaging industries are in an ongoing transition to lead free soldering due to the adverse effect on environment and human health [1]. Sn-Ag-Cu (SAC) have been recognized as promising alternatives due to its low eutectic temperature, higher wettability and strength, superior resistance to creep and thermal fatigue. Surface roughness has a significant influence on mechanical parameters determined nanoindentation tests. Although research has been conducted to analyze the mechanical properties of bulk SAC material, there have been limited prior studies on SAC thin films and their mechanical properties since fabricating a smooth SAC thin film is a fundamental challenge. SAC thin films with four different Sn–Ag–Cu ternary eutectic composition: 96.5Sn-3.0Ag-0.5Cu, 95.5Sn-3.8Ag–0.7Cu, 95.5Sn-3.9Ag–0.6Cu & Sn-4.0Ag–0.5Cu will be deposited using RF magnetron sputtering with different deposition rates and annealed at various temperature to fabricate a smooth continuous film. Figures 1 and 2 depict SAC05 deposited using RF magnetron sputtering at Figure 1: SEM image of SAC-05 surface at 10,000X. 20W, 2.4 mTorr pressure, and argon flow flow rate of 20.5 sccm. Surface morphology will be examined using Field emission Scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM). Crystallinity of the deposited film will be examined using X-ray diffraction (XRD). Mechanical properties will be studied using nanoindentation [2]. Properties of the thin film will be compared with the bulk material with similar eutectic composition.References M. Abtew G. Selvaduray. (2000). Lead-free Solders in Microelectronics. Materials Science & Engineering. a Review Journal., 27(5-6), 95.Long, X., Wang, S., Feng, Y., Yao, Y., & Keer, L. M. (2017). Annealing Effect on Residual Stress of Sn-3.0Ag-0.5Cu Solder Measured by Nanoindentation and Constitutive Experiments. Materials Science and Engineering: A, 696, 90-95. Figure 1

Micro solder bump detection of flip chip using improved decision tree model based on SAM image

The increasing packaging density of flip chips brings great challenges for micro defect detection. It is necessary to develop an efficient and automatic inspection system for electronic industrial application. In this paper, the scanning acoustic microscopy (SAM) technology and the optimized classifier were investigated for the automatic detection of solder joint defects of flip chips. Ultrasonic images of 1902 solder bumps from 6 chip samples were obtained using a SAM equipment. The decision tree model was improved by introducing the granularity decision entropy. The feature vectors were extracted from the images of solder bumps, and then used for classification. The results show that the decision tree model correctly detected 1812 solder bumps with the accuracy of 95.3%. It is verified that the ultrasonic defect detection system based on the improve decision tree model has high accuracy for micro defect inspection, which has potential and promising application in the electronic packaging industry.

Interfacial engineering of epoxy/silica nanocomposites by amino-rich polyethyleneimine towards simultaneously enhanced rheological and thermal-mechanical performance for electronic packaging application

As electronic devices move toward miniaturization and high-degree integration, it becomes imperative to use nano-sized silica as a reinforcing filler for epoxy resin in modern electronics packaging industries. However, the use of silica nanoparticles (SNPs) brings about new challenges in filler dispersion and in the balance between the rheology and thermal mechanical performance of epoxy nanocomposites. This study presents a novel strategy aiming to address the above challenges by interface engineering with amino-rich branched polyethyleneimine (PEI) polymer molecules through a facile self-assembly process. This not only enables a considerable decrease (by 79.7%) in viscosity accompanied by a significant improvement in viscosity stability (only 2.7 times increase after 24 h) but also leads to a further CTE reduction of 4.8 ppm/°C (equivalent to the effects of around 10 wt% SNPs) relative to the SNPs. This work offers a new direction and efficient approach to develop high-performance epoxy composites for electrical packaging applications as well as provides some fresh insights into the interface-property relationships.

Microstructure evolution and bonding mechanism of ZrO2 ceramic and Ti-6Al-4V alloy joints brazed by Bi2O3-B2O3-ZnO glass paste

Ceramics and metal joinings have been widely employed in aerospace, dental implants, and the electronic packaging industry for fabricating multifunctional components. In this study, the 35Bi2O3-50B2O3-15ZnO (mol.%) glass has been employed for joining the ZrO2 ceramic and Ti-6Al-4V alloy. The effect of brazing temperature on the microstructure evolution, mechanical properties, and bonding mechanism of brazed joints has been analyzed. The microstructure of the ZrO2/glass/Ti-6Al-4V joints and the content of Bi4B2O9, Bi2O3 and Bi24B2O39 precipitated crystals in glass were found to be dependent on the brazing temperature. The reaction product of Bi4Ti3O12 was identified in the glass/Ti-6Al-4V interface because of the chemical reaction between the oxidized layer of Ti-6Al-4V alloy and glass. A maximum shear strength as high as 48.8 ± 5.2 MPa was obtained. Our work, thus, demonstrates that the 35Bi2O3-50B2O3-15ZnO glass is an effective bonding material for joining ZrO2 ceramic and Ti-6Al-4V alloy under low temperature in an ambient atmosphere.

High-performance cellulose acetate-based gas barrier films via tailoring reduced graphene oxide nanosheets

Improving the gas molecule barrier performance and structural stability of bio-plastic films dramatically contribute to packaging and protective fields. Herein, we proposed a novel nanocomposite film consisting of cellulose acetate (CA)/polyethyleneimine (PEI)/reduced graphene oxide (rGO)-NiCoFeOx) with high gas barrier property by applying “molecular glue” and “nano-patching” strategies. Systematical investigations demonstrated that the CA/rGO interfacial interaction was effectively enhanced due to the “molecular glue” role of PEI chains via physical/chemical bonds and the defective regions in rGO plane were nano-patched through hydrophilic interactions between edged oxygen-containing functional groups and ultrafine NiCoFeOx nanoparticles (~3 nm). As a result, the oxygen and moisture transmission rates of the prepared CA/PEI/rGO-NPs hybrid film were significantly reduced to 0.31 cm3 ∗ μm/(m2 ∗ d ∗ kPa) and 314.23 g/m2 ∗ 24 h, respectively, which were 99.60% and 54.69% lower than pristine CA films. Meanwhile, the tensile strength of hybrid film was increased from 25.90 MPa to 40.67 MPa. More importantly, the designed nanocomposite film possesses excellent structural stability without obvious GO layer shedding and hydrophobicity attenuation after persistent bending at least 100 times. The exceptional robust and high gas barrier film displays great promising application in food, agriculture, pharmaceuticals and electronic instruments packaging industry.