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We review the GPAW open-source Python package for electronic structure calculations. GPAW is based on the projector-augmented wave method and can solve the self-consistent density functional theory (DFT) equations using three different wave-function representations, namely real-space grids, plane waves, and numerical atomic orbitals. The three representations are complementary and mutually independent and can be connected by transformations via the real-space grid. This multi-basis feature renders GPAW highly versatile and unique among similar codes. By virtue of its modular structure, the GPAW code constitutes an ideal platform for the implementation of new features and methodologies. Moreover, it is well integrated with the Atomic Simulation Environment (ASE), providing a flexible and dynamic user interface. In addition to ground-state DFT calculations, GPAW supports many-body GW band structures, optical excitations from the Bethe–Salpeter Equation, variational calculations of excited states in molecules and solids via direct optimization, and real-time propagation of the Kohn–Sham equations within time-dependent DFT. A range of more advanced methods to describe magnetic excitations and non-collinear magnetism in solids are also now available. In addition, GPAW can calculate non-linear optical tensors of solids, charged crystal point defects, and much more. Recently, support for graphics processing unit (GPU) acceleration has been achieved with minor modifications to the GPAW code thanks to the CuPy library. We end the review with an outlook, describing some future plans for GPAW. [ABSTRACT FROM AUTHOR]

The demand for applications, such as coatings, separation filters, and electronic packaging, has greatly driven the research of polymer films. At nanometer scale, mechanical properties of thin polymer films can significantly deviate from bulk. Despite outstanding progresses, there still lack deep discussions on nonlinear viscoelastic–viscoplastic response and their interactions under nanoconfinement. In this work, by conducting measurements via the bubble inflation method and modelling using Schapery and Perzyna equations, we demonstrate nonlinear viscoelastic–viscoplastic properties of freely standing thin polystyrene (PS) films. The results show the unchanged glassy compliance and the rubbery stiffening phenomenon for thin PS films, where the lower rubbery plateau in rubbery stiffening may originate from the induced molecular orientation by plastic deformation. With decreasing film thickness, viscosity and yield stress in viscoplasticity increase in an exponential and a linear trend, respectively, indicating the significant role of nanoconfinement effect on viscoplastic properties. These findings may reveal that there are many properties from linear viscoelasticity to nonlinear viscoelasticity–viscoplasticity that need to be explored and unveiled for sufficient understanding of the nanoconfinement effect on altering mechanical behavior of polymers. [ABSTRACT FROM AUTHOR]

The remarkable progress in the fields of aerospace, transportation, electronic packaging, and other industries has sparked a growing need for Al matrix composites (AMCs) with extraordinary mechanical properties. As ideal reinforcements for fabricating lightweight AMCs, oxide ceramics have garnered extensive attention due to their impressive attributes such as exceptional strength, high melting point, commendable chemical stability and resistance to oxidation. Especially, the AMCs reinforced with in situ oxide ceramics have shown more promising prospects for enhancing the compatibility of reinforcement-matrix interface and manipulating reinforcement dispersion compared to the counterparts with ex situ reinforcements, as they usually involve the formation of reinforcements through in situ chemical reactions between elements or compounds. This review focuses on recent advancements in preparation strategies, exploring the in situ reaction mechanisms and microstructural characteristics, as well as unraveling the remarkable mechanical properties of in situ oxide ceramic-reinforced AMCs. The crucial role of in situ reactions in governing reinforcement characteristics such as distribution, size, dimension, and the reinforcement-matrix interfacial structure is particularly underscored. The review is expected to facilitate a comprehensive understanding of the interplay between the various facets of the subject, which hold significant implications for guiding the development of high-performance AMCs. [ABSTRACT FROM AUTHOR]

The negative thermal expansion material ZrV 2 O 7 exhibits superior performance and holds significant potential for applications. In this study, the medium entropy concept was employed to successfully synthesize (Zr 1/3 Hf 1/3 Ti 1/3)V 2 O 7 , with metal atoms (Ti, Zr, and Hf) occupying the position of Zr in ZrV 2 O 7. The material shows a negative thermal expansion coefficient of 4.2 × 10-6K-1, which is essentially consistent with the crystal structure and expansion performance of ZrV 2 O 7. However, (Zr 1/3 Hf 1/3 Ti 1/3)V 2 O 7 demonstrates higher softening temperature and thermal stability. This study simplified the complex preparation process of the material, broadening its negative thermal expansion range and enhancing its high-temperature stability. Furthermore, the material possesses a significant dielectric constant of 2.24 × 108 (log f <1) and a high hardness of 187.7 HV0.5, making it a new type of dielectric ceramic material. It has great potential for applications in the fields of energy storage and electronic packaging. [ABSTRACT FROM AUTHOR]

In electronic packaging products in the service process, the solder joints experience thermal fatigue due to temperature cycles, which have a significant influence on the performance of electronic products and the reliability of solder joints. In this paper, the thermal fatigue failure mechanism of solder joints in microelectronic packages, the microstructure changes of the thermal fatigue process, the influence factors on the joint fatigue life, and the simulation analysis and forecasting of thermal fatigue life are reviewed. The results show that the solder joints are heterogeneously coarsened, and this leads to fatigue cracks occurring under the elevated high-temperature phase of alternating temperature cycles. However, the thickness of the solder and the hold time in the high-temperature phase do not significantly influence the thermal fatigue. The coarsened region and the IMC layer thicken with the number of cycles, and the cracks initiate and propagate along the interface between the intermetallic compound (IMC) layer and coarsened region, eventually leading to solder joint failure. For lead-containing and lead-free solders, the lead-containing solder shows a faster fatigue crack growth rate and propagates by transgranular mode. Temperature and frequency affect the thermal fatigue life of solder joints to different degrees, and the fatigue lifetime of solder joints can be predicted through a variety of methods and simulated crack trajectories, but also through the use of a unified constitutive model and finite element analysis for prediction. [ABSTRACT FROM AUTHOR]

Glass-to-metal seals are a very important element in the construction of vacuum tubes, electric discharge tubes, pressure-tight glass windows in metal cases, and metal or ceramic packages of electronic components. This paper presents the influence of different pretreatment methods on the high-temperature wettability of 304 stainless steel by high-alumina glass sealing. The pretreatment of the steel included laser surface melting and pre-oxidizing. The bonding characteristics of glass and stainless steel directly depend on the wettability in terms of the measured wetting angle, the type of oxide formed at the stainless steel surface, and the microstructural changes during the manufacturing process. The oxide film thickness on the stainless steel surface was evaluated to determine the optimal parameters. The film was wetted with high-alumina glass powder at different temperatures. The results showed that pre-oxidation decreased the wetting angle from 56.2° to 33.6°, while for the laser-melted surface, the wetting angle decreased from 49.8° to 31.5°. Scanning electron microscopy (SEM) revealed that the oxide film on the laser-melted surface was thicker and denser than that formed on the pre-oxidized surface. The present work shows that laser surface melting has a greater beneficial influence on the wetting and diffusion characteristics of 304 stainless steel sealed by high-alumina glass. [ABSTRACT FROM AUTHOR]

SnPb solder was widely used in electronic packaging for aerospace devices due to its high reliability. However, its creep resistance is poor and can be improved by adding alloying elements. The effects of Sb content on the microstructure, tensile, and creep properties of eutectic SnPb solder were investigated. Sb addition effectively improved the mechanical properties of the SnPb solder. When Sb content exceeds 1.7 wt.%, SbSn intermetallic compounds (IMCs) occurred. And increasing the Sb content increased the tensile strength. Furthermore, Sb addition decreased the steady-state creep rate and increased the stress exponent n, suggesting that the creep resistance had been enhanced, which may be attributed to the hindrance of dislocation movement by SbSn IMCs, as well as the reduction in phase boundaries, which consequently reduced grain boundary sliding. [ABSTRACT FROM AUTHOR]

Polyacrylate‐based electrically conductive adhesives (PA‐based ECAs) have attracted much attention due to their wide applications in precise instruments and consumer electronics. To obtain high‐performance and environmentally friendly PA‐based ECAs, their main properties and corresponding mechanisms to performance, chemical constitutions and structure–function relationships should be well understood, and the applications of recent PA‐based ECAs should be comprehensively summarized. This review focuses on the progress of PA‐based ECAs in the past two decades and discusses the featured properties, preparation of PA, the selection of conductive fillers and the adhibition of the ECAs. The aim of the review is to find the challenges of high‐performance ECAs and offer some measures and foresee their future development. Highlights: Preparation methods of polyacrylate (PA)‐based composites are presented.Properties of PA‐based electrically conductive adhesives (ECAs) are outlined.Selection of conductive fillers and the adhibition of ECAs are discussed.Representative applications of PA‐based ECAs are exhibited.Present main challenges and future solutions are highlighted. [ABSTRACT FROM AUTHOR]

Content: In this thesis, the role of N atom doping and biaxial strain in modulating the electronic structure and optical properties of antimonene has been deeply investigated using a first-principles approach based on density-functional theory. The results show that N doping significantly reduces the band gap of antimonene and introduces new electronic states, thus affecting its electronic structure. In terms of optical properties, N doping reduces the static permittivity of antimonene and alters its absorption, reflection, and energy loss properties. In addition, biaxial strain further enhanced the modulation effect of these properties. This study not only provides theoretical support for the application of antimonene in the field of high-performance two-dimensional electronic and optoelectronic devices, but also reveals strain and doping as an effective means to modulate the physical properties of two-dimensional materials. Methods: For the calculations, we used the DFT-based CASTEP software package for the simulation of the electronic structure. In order to more accurately characterize the weak interactions between two-dimensional materials, we specifically introduced the Van der Waals dispersion correction. We have chosen the Perdew-Burke-Ernzerhof (PBE) exchange-correlation generalization under the generalized gradient approximation (GGA) and combined it with the Van der Waals correction term in order to fully consider the electronic structure of antimonene. For the calculation parameter settings, we set the truncation energy to 400 eV to ensure the accuracy of the calculation. Meanwhile, we adopt a 6 × 6 × 1 k-point grid for Brillouin zone sampling to obtain more accurate energy band structure and density of states information. For the convergence settings, the convergence criteria for both the system energy and the interaction force between atoms were set to 1 × 10−5 eV and 0.01 eV/Å, respectively. We selected a 3 × 3 × 1 supercell model with 18 Sb atoms. A vacuum thickness of 18 Å was established in the Z direction, which is sufficient to avoid interactions between the two atomic layers above and below the periodic structure. [ABSTRACT FROM AUTHOR]

Silicon carbide (SiC) power devices are attracting significant attention due to their outstanding stability in high-voltage, high-temperature, and highfrequency environments. To replace toxic Pb-based glass, there is an urgent need to develop Pb-free glass for SiC power device encapsulation, considering its superior electrical insulation properties and processing capabilities. Here, we developed a Bi-based glass for effective encapsulation practical of SiC power devices. By increasing the content of glass modifier BaO, the structure of bismuth borate glass can be tuned to reduce glass network density, leading to the transition of structural units from [BO4] to [BO3]. The softened temperature is reduced to 363.4°C with the BaO content increasing to 15 mol%. After encapsulating the SiC power devices using Bi-based glass, the glass demonstrated a reverse breakdown voltage of 650 V and an extremely low leakage current. Therefore, ourwork provided a route for adapting Pb-free-based low-melting glass for encapsulating SiC devices and offered potential for advanced semiconductor packaging. [ABSTRACT FROM AUTHOR]

Purpose: Au stud bump bonding technology is an effective means to realize heterogeneous integration of commercial chips in the 2.5D electronic packaging. The purpose of this paper is to study the long-term reliability of the Au stud bump treated by four different high temperature storage times (200°C for 0, 100, 200 and 300 h). Design/methodology/approach: The bonding strength and the fracture behavior are investigated by chip shear test. The experiment is further studied by microstructural characterization approaches such as scanning electron microscope, energy dispersive spectrometer and so on. Findings: It is recognized that there were mainly three typical fracture models during the chip shear test among all the Au stud bump samples treated by high temperature storage. For solder bump before aging, the fracture occurred at the interface between the Cu pad and the Au stud bump. As the aging time increased, the fracture mainly occurred inside the Au stud bump at 200°C for 100 and 200 h. When aging time increased to 300 h, it is found that the fracture transferred to the interface between the Au stud bump and the Al Pad. Originality/value: In addition, the bonding strength also changed with the high temperature storage time increasing. The bonding strength does not change linearly with the high temperature storage time increasing but decreases first and then increases. The investigation shows that the formation of the intermetallic compounds because of the reaction between the Au and Al atoms plays a key role on the bonding strength and fracture behavior variation. [ABSTRACT FROM AUTHOR]

Purpose: This paper aims to compare and evaluate the influence of package designs and characteristics on the mechanical reliability of electronic assemblies when subjected to harmonic vibrations. Design/methodology/approach: Using finite element analysis (FEA), the effect of package design-related parameters, including the interconnect array configuration, i.e. full vs perimeter, and package size, on solder mechanical stresses are fully addressed. Findings: The results of FEA simulations revealed that the number of solder rows or columns available in the array, could significantly affect solder stresses. In addition, smaller packages result in lower solder stresses and differing distributions. Originality/value: In literature, there are no papers that discuss the effect of solder array layout on electronic packages vibration reliability. In addition, general rules for designing electronic assemblies subjected to harmonic vibration loadings are proposed in this paper. [ABSTRACT FROM AUTHOR]

Nanoporous Cu foam is widely applied in many fields such as the packaging of electronic power devices. In this study, a sandwich-structured Cu-Zn eutectic alloy precursor composed of Cu0.53Zn0.47/Cu5Zn8/Cu0.53Zn0.47 is prepared through electroplating. The surface layer of the precursor, Cu0.53Zn0.47, has a flat surface with numerous grain boundaries, which effectively promotes its dealloying behavior. By contrast, Cu5Zn8 has a porous structure, which promotes the dealloying behavior at the center of the precursor. The dealloying of Cu0.53Zn0.47 is dominated by the coherent surface diffusion of Cu atoms, and the crystal lattice and orientation show no changes before and after dealloying. By contrast, the dealloying behavior of Cu5Zn8 requires the renucleation of Cu crystals; in this process, Cu atoms are transported to the surface of the layer by capillary forces to form clusters, which nucleate and grow. [ABSTRACT FROM AUTHOR]

WHO recommends that electronic medication monitors, a form of digital adherence technology, be used as a complement to directly observed treatment (DOT) for tuberculosis, as DOT is inconvenient and costly. However, existing evidence about the effectiveness of these monitors is inconclusive. Therefore, we evaluated the effectiveness of a comprehensive package based on electronic medication monitors among patients with tuberculosis in Tibet Autonomous Region (hereafter Tibet), China. This multicentre, randomised controlled trial recruited patients from six counties in Shigatse, Tibet. Eligible participants had drug-susceptible tuberculosis and were aged 15 years or older when starting standard tuberculosis treatment. Tuberculosis doctors recruited patients from the public tuberculosis dispensary in each county and the study statistician randomly assigned them to the intervention or control group based on the predetermined randomised allocation sequence. Intervention patients received an electronic medication monitor box. The box included audio medication-adherence reminders and recorded box-opening data, which were transmitted to a cloud-based server and were accessible to health-care providers to allow remote adherence monitoring. A linked smartphone app enabled text, audio, and video communication between patients and health-care providers. Patients were also provided with a free data plan. Patients selected a treatment supporter (often a family member) who was trained to support patients with using the electronic medication monitor and app. Patients in the control group received usual care plus a deactivated electronic medication monitor, which only recorded and transmitted box-opening data that was not made available to health-care providers. The control group also had no access to the app or trained treatment supporters. The primary outcome was a binary indicator of poor monthly adherence, defined as missing 20% or more of planned doses in the treatment month, measured using electronic medication monitor opening data, and verified by counting used medication blister packages during consultations. We recorded other secondary treatment outcomes based on national tuberculosis reporting data. We analysed the primary outcome based on the intention-to-treat population. This trial is registered at ISRCTN, 52132803. Between Nov 17, 2018, and April 5, 2021, 278 patients were enrolled into the study. 143 patients were randomly assigned to the intervention group and 135 patients to the control group. Follow-up ended when the final patient completed treatment on Oct 4, 2021. In the intervention group, 87 (10%) of the 854 treatment months showed poor adherence compared with 290 (37%) of the 795 months in the control group. The corresponding adjusted risk difference for the intervention versus control was –29·2 percentage points (95% CI –35·3 to –22·2; p<0·0001). Five of the six secondary treatment outcomes also showed clear improvements, including treatment success, which was found for 133 (94%) of the 142 individuals in the intervention arm and 98 (73%) of the 134 individuals in the control arm, with an adjusted risk difference of 21 percentage points (95% CI 12·4–29·4); p<0·0001. The interventions were effective at improving tuberculosis treatment adherence and outcomes, and the trial suggests that a comprehensive package involving electronic medication monitors might positively affect tuberculosis programmes in high-burden and low-resource settings. TB REACH. [ABSTRACT FROM AUTHOR]

Epoxy resins are used in electronic packaging. However, its low thermal conductivity is a disadvantage and the high moisture absorption leads to defects such as cracking and delamination. In this work, the effect of thermo‐mechanical properties of epoxy resins under moisture‐heat coupling is investigated by molecular dynamics (MD) simulations. The diglycidyl ether of bisphenol A (DGEBA) and polyetheramine D230 are used as epoxy resin matrix and curing agents, respectively. The degree of cross–linking is set from 0% to 98% and the moisture mass fraction is set from 0 wt.% to 10 wt.%. The radius distribution function(RDF) shows that water molecules tend to appear ≈2.75 Å from the epoxy resin. The thermal conductivity of the epoxy resin increases by 54.55% for the maximum cross–linking degrees studied. And it increases by 19.23% when the moisture mass fraction is increased from 0 wt.% to 10 wt.%. The deformation of the epoxy resin is calculated which includes the coefficient of thermal expansion(CTE), coefficient of moisture expansion(CME), and coefficient of linear expansion. It is found that moisture expansion predominated at low temperatures and thermal expansion dominates at high temperatures. The analysis provides a theoretical basis for the study of hygrothermal coupling effects. [ABSTRACT FROM AUTHOR]

Poly(ether-ketone)/fly ash (FA) composites reinforced with 0-30 wt% FA were fabricated using ball milling followed by hot compaction. The composites were investigated for mechanical and viscoelastic properties. Scanning electron microscopy revealed excellent dispersion and good adhesion of FA particles with the matrix. The addition of FA increased the microhardness by 70% and the storage modulus (below glass transition) by 75%. The reinforcing efficiency was better above the glass transition, which increased to around 177% at 250°C. This research indicates that the FA can be used as an alternative reinforcement of costly ceramic powder for the electronic packaging substrate or printed circuit board applications. [ABSTRACT FROM AUTHOR]

The mesophase pitch-based carbon fiber interface material (TIM) with a vertical array was prepared by using mesophase pitch-based short-cut fibers (MPCFs) and 3016 epoxy resin as raw materials and carbon nanotubes (CNTs) as additives through electrostatic flocking and resin pouring molding process. The microstructure and thermal properties of the interface were analyzed by using a scanning electron microscope (SEM), laser thermal conductivity and thermal infrared imaging methods. The results indicate that the plate spacing and fusing voltage have a significant impact on the orientation of the arrays formed by mesophase pitch-based carbon fibers. While the orientation of the carbon fiber array has a minimal impact on the shore hardness of TIM, it does have a direct influence on its thermal conductivity. At a flocking voltage of 20 kV and plate spacing of 12 cm, the interface material exhibited an optimal thermal conductivity of 24.47 W/(m·K), shore hardness of 42 A and carbon fiber filling rate of 6.30 wt%. By incorporating 2% carbon nanotubes (CNTs) into the epoxy matrix, the interface material achieves a thermal conductivity of 28.97 W/(m·K) at a flocking voltage of 30 kV and plate spacing of 10 cm. This represents a 52.1% increase in thermal conductivity compared to the material without TIM. The material achieves temperature uniformity within 10 s at the same heat source temperatures, which indicates a good application prospect in IC packaging and electronic heat dissipation. [ABSTRACT FROM AUTHOR]

This research focuses on developing high-fidelity experimental and numerical models to analyze microscale underfill dynamics and void formation in high-density flip-chip packaging. Three underfilling scenarios are investigated, namely, point type, I-shaped line type, and L-type line type. The point-type underfilling validates the numerical model against experimental results, while the I-shaped and L-type line-type underfilling explore grid independence, void formation, and critical parameters such as filling position, contact angle, and liquid viscosity. Results indicate that contact angle and viscosity significantly influence filling efficiency and interface evolution. A smaller contact angle accelerates the process, reducing interface jumping motions. Viscous effects are quantified, revealing dimensionless filling time convergence. The use of low-viscosity surrogate fluids enhances numerical simulation efficiency. Sub-bump-sized, bump-sized, and sup-bump-sized voids are observed, identifying three void formation scenarios representing different underfilling flow mechanisms. This study provides insight into microscale flip-chip underfill physics and establishes validated models for next-generation high-density flip-chip products. These models can be further refined and integrated into optimization tools for automated process design, contributing to improved assembly yield and reliability of emerging electronic packages through physics-based understanding and modeling. [ABSTRACT FROM AUTHOR]

The die shear test is a feasible and conventional method to characterize the shear strength of die‐attaching layer materials in electronic packaging. A new method for determining cohesive zone model (CZM) parameters using deep neural networks (DNN) and die shear tests is proposed, different from classical fracture framework or lap shear test‐based methods. With the sintered nano‐silver die shear test, the results show that the bilinear CZM inversion results agree well with the experimental results. It is found that the DNN model has high accuracy in predicting and identifying the maximum shear traction strength τmax, separation displacement of the interface δf, and the interface stiffness k1 of CZM parameters for sintered nano‐silver adhesive layer through die shear test load versus displacement curves. The presented DNN‐aided inverse identifying method through the die shear test in this paper could provide an alternative and convenient method for extracting CZM parameters of various kinds of adhesive materials in electronic packaging. Highlights: Die shear tests were used for the inverse identification of CZM parameters.The die shear test P–δ curves were established as the dataset.A DNN‐aided CZM inverse identification method was proposed.The DNN‐aided model can accurately identify the CZM parameters. [ABSTRACT FROM AUTHOR]

In the rapidly developing microelectronics industry and technology, epoxy resin based electrically conductive adhesives must be urgently improved in terms of aging resistance, especially residual stress caused by thermal cycle aging. In this study, we investigated the stress behavior of rigid and flexible epoxy systems blended with bisphenol F epoxy (BPF) and fatty acid epoxy. The curing processes, thermal, and thermomechanical properties of the modified epoxy systems were assessed comprehensively. Moreover, the residual stress during the thermal cycle was monitored, and the bond strength was characterized. The results pointed out that by introducing soft molecular segments into a rigid system, the modified epoxy resin system had significantly lower residual stress values and exhibited a higher bond strength over a wider temperature range. Finally, we envision the systematic integration of residual stress testing with material strength testing for quantifying the bond failure of adhesive layers in the near future. [ABSTRACT FROM AUTHOR]

This paper presents a numerical analysis of different rheology models during the encapsulation of moulded underfill (MUF) for flip-chip package. Robust computational fluid dynamics of finite volume analysis software; ANSYS FLUENT Workbench 14.5 was utilised in three-dimensional. A remarkable analysis was carried out by considering three distinctions among rheology models, namely Power Law, Cross, and Castro-Macosko. Nevertheless, a unique function has been written for the Castro–Macosko model since it considers the curing effect using user-defined functions. The volume of fluid technique was utilised to track the flow front of epoxy moulding compound (EMC). Beforehand, the flow visualization for the tray cavity has been verified by both experiment and simulation qualitatively, and it has been found to be in good agreement. It also conformed to the rheological properties, i.e., viscosity and shear rate. For MUF encapsulation, the 3D views of the melt front profile during encapsulation were presented. In addition, the viscosity-shear rate and void formation versus rows of multi-flip chips for all models were plotted and discussed. The numerical results have shown that the best rheology model for EMC during encapsulation was the Castro-Macosko model with consideration of curing effect. It was clearly found that the retardation flow occurred since the conversion of EMC took place, i.e., the curing effect. The present numerical analysis is expected to grant a good understanding of epoxy behaviour for engineers and designers in the electronic packaging industry. [ABSTRACT FROM AUTHOR]

The dielectric properties and polarization mechanism are important for the application of high thermal conductivity electronic packaging materials. In this work, diamond/SiC composites were prepared by the silicon vapor infiltration process, and the effect of diamond content on permittivity of composites was investigated in detail in the range of 100 MHz to 1 GHz, and the mechanism of dielectric polarization was also discussed. The results show that the real part of permittivity of composite is greater than that of either component, due to the presence of interfaces and defects. As the diamond content increases, both the real and imaginary parts of permittivity show a trend of rapid decrease and then slow increase. Particularly, the minimum values of the real and imaginary parts of permittivity of diamond/SiC composite are 27 and 0.3, respectively. In the low frequency stage (<400 MHz), the dielectric loss of the composite is mainly caused by the conductivity loss, while in the high frequency stage (400 MHz∼1 GHz), the polarization loss plays a dominant role. The polarization loss of diamond/SiC composite mainly originates from several Debye relaxation processes, which are the interfacial polarization formed at the diamond/graphite and graphite/SiC interfaces. [ABSTRACT FROM AUTHOR]

This work presents a technique to estimate the spatially varying thermal contact conductance (TCC) over the contact zone of non-conformal bolted joints, which are common in satellite structures for mounting of the electronic packages, through a coupled thermal and structural analysis. The heat flow across an interface occurs only through the actual regions of contact rather than the apparent contact area and is governed by the TCC at the interface. Due to its multi scale nature, accurate estimation of TCC is very challenging. In this work, the TCC between two plates, which are joined using a single bolt at the center is determined for four prescribed bolt torques viz. 1.5, 3.0, 4.5 and 6.0 Nm, using non-intrusive temperature measurements performed at locations away from the actual interface. TCC depends upon micro contact conductance of surface asperities and also on the macroscopic deflection of plates occurring due to the application of bolt torque. The effect of micro contact conductance due to surface asperities are modelled by making the TCC a linear function of applied torque. The macroscopic deformation of plates are found by solving the three dimensional state of stress using finite element analysis. The slope parameter connecting TCC and contact pressure is estimated for each torque, for a specified heat flux and sink temperature, via an inverse technique by minimizing the difference between the simulated temperature obtained by the assumed value of slope parameter and the one obtained from the experiments in a least square sense. Subsequently, the estimated values of the TCC are validated by comparing the simulated temperatures with the measured ones obtained from the experiments performed at different conditions (heat fluxes and sink temperatures) for each bolt torque. As the bolt torque increases, due to the deformation of the asperities, the actual contact area increases and approaches the macroscopic contact area. Consequently, the TCC increases and tends to reach a saturation value. This is also manifested by the estimated slope parameter approaching a constant value asymptotically as the bolt torques are increased. [ABSTRACT FROM AUTHOR]

The impinging jet is a complex heat and mass transfer technique that involves several process variables, such as the jet Reynolds number, impingement distance, and jet configuration. In this study, the flow characteristics of a semi-confined circular-pipe impinging jet over different Reynolds numbers and impingement distances were experimentally investigated using a two-dimensional particle image velocimetry technique. The confinement was achieved by positioning a plate parallel to the impinging plate at the nozzle exit. The time-averaged velocity field exhibited a recirculation structure that gradually shifted downstream with increasing Reynolds numbers or impingement distances. Notably, at H/d = 2, this downstream shift of the structure was accompanied by an increase in the vortex intensity. Moreover, the confined plate induced alterations in the overall flow pattern within the confined region, significantly reducing the wall jet decay rate compared with both unconfined and confined radial wall jets for H/d ≥ 3. Conversely, the confinement did not affect the expansion of the wall jet. Unlike the free (unconfined) impinging jets, the semi-confined circular-pipe impinging jet did not exhibit self-similar behavior in the conventional outer-scaled coordinates, particularly concerning the turbulence intensity and Reynolds shear stress. Finally, self-similarity in the time-averaged velocity and various turbulence parameters was achieved using the parameter scale proposed in this study, thereby obtaining the corresponding scaling laws in the wall jet region. Our study results can deepen the current understanding of the flow characteristics of semi-confined circular-pipe impinging jets and are significant for optimizing the performance and efficiency of compact electronic packaging equipment. [ABSTRACT FROM AUTHOR]

Conventional polymers have typically been used in the packaging of various electronic devices; however, due to the inherent electrically insulating properties these materials fail to dissipate static charges. To address this issue, novel poly(ether-b-amide) (PEBA) segmented copolymers consisting of uniform rigid oxalamide and flexible polyethylene glycol (PEG) were synthesized via melt polycondensation. The influence of PEG molecular weight and the spacer length separating two oxalamide units on the condensed structure, mechanical performance, and antistatic properties was systematically investigated. Fourier-transform infrared (FTIR) demonstrated strongly hydrogen bonded and highly ordered oxalamide hard segments with the degree of ordering between 71 and 85 % even at low levels. Mechanical behavior results showed that segmented copolymers have an obvious yield point, an elastic modulus between 20 and 30 MPa, and strain at break exceeding 2000 %. Meanwhile, such copolymers possessed low surface resistivity, as low as 107 Ω, which is significantly less than that of commercial antistatic additives. The antistatic effect of PEBA on polyamide 6 (PA6) was also investigated, revealing that when the content reached 30 wt%, the surface resistivity of the alloys decreased from 1013 Ω to 1011 Ω and remained stable after 40 days, even after water washing treatment. Overall, these findings illustrate that the newly synthesized PEBA copolymers demonstrate outstanding long-term antistatic properties and provide valuable insights for the development of polyether-based multiblock copolymer antistatic agents. [ABSTRACT FROM AUTHOR]

Polyimide (PI) film with hydrophilic greatly limits their application in the field of microelectronic device packaging. A novel hydrophobic PI film with sag structure and improved mechanical properties is prepared relying on the reaction between anhydride‐terminated isocyanate‐based polyimide (PIY) containing a seven‐membered ring structure and the amino‐terminated polyamide acid (PAA) via multi‐hybrid strategy, this work named it as hybrid PI film and marked it as PI‐PIY‐X. PI‐PIY‐30 showed excellent hydrophobic properties, and the water contact angle could reach to 102°, which is 20% and 55% higher than simply PI film and PIY film, respectively. The water absorption is only 1.02%, with a decrease of 49% and 53% compared with PI and PIY. Due to that the degradation of seven‐membered ring and generation of carbon dioxide led to the formation of sag structure, the size of sag structures is ≈16.84 and 534.55 nm for in‐plane and out‐plane direction, which are observed on surface of PI‐PIY‐30. Meanwhile, PI‐PIY‐30 possessed improved mechanical properties, and the tensile strength is 109.08 MPa, with 5% and more than 56% higher than that of pure PI and PIY film, showing greatly application prospects in the field of integrated circuit. [ABSTRACT FROM AUTHOR]

Introduction Youth represent a high-priority group for e-cigarette health communication. This study examined youth exposure to the Food and Drug Administration (FDA) e-cigarette warning label over 4 years and its association with change in youth harm perception and intention. Aims and Methods We pooled data from the 2018–2021 National Youth Tobacco Survey (age 10–17; n  = 67 159). Participants were divided into four groups: never users (58.5%), susceptible nonusers (16.3%), former users (12.7%), and current users (12.5%). We examined the prevalence, time-trend, correlates, and association of youth exposure to the warning with addictiveness and harm perception, intention to use e-cigarettes, and intention to quit all tobacco products. Results Only 24.5% of youth were exposed to the warning. Exposure increased from 14.9% in 2018 to 30.8% in 2019, then declined to 25.2% in 2021. Hispanic (adjusted odds ratio (aOR) = 0.76 [95% CI = 0.641 to 0.89]) and non-Hispanic black current users (0.53 [0.40 to 0.69]) were less likely to be exposed to the warning than white current users. Youth exposure was positively associated with a higher perception of e-cigarette addictiveness (1.12 [1.04 to 1.19]) and intention to quit all tobacco products (1.28 [1.13 to 1.46]). However, exposure was negatively associated with harm perception (0.91 [0.85 to 0.96]) and the intention to use e-cigarettes among e-cigarette nonusers (2.38 [1.99 to 2.84]). Conclusions The decline in youth exposure to the warning indicates wear-out effects. Strengthening the label by using compelling designs, adding themes on e-cigarette harm to youth, periodically rotating warning content, and using culturally tailored messaging may improve its impact on youth and address racial/ethnic disparities. Implications The FDA e-cigarette label reached only 24.5% of youth, and exposure to the warning declined to indicate wear-out effects. Exposure was significantly lower among minorities. Exposure was associated with a higher perception of e-cigarette addictiveness and intention to quit all tobacco products. Still, it did not increase harm perception or reduce intention to use e-cigarettes among nonusers. Strengthening the label by using more compelling designs, including diverse themes focusing on e-cigarette harm relevant to youth, and periodically rotating warning content may improve its impact on youth. Continued surveillance of the implementation of e-cigarette policies is needed to ensure that they equally affect youth across racial/ethnic subpopulations. [ABSTRACT FROM AUTHOR]

The high integration density of microelectronic devices leads to local heat accumulation, and effective heat dissipation and signal transmission of packaging materials have become the primary issues to be solved. However, existing polymer materials have difficulty meeting the requirements due to their unsatisfactory thermal conductivity and thermal expansion properties. In this work, we proposed the use of digital light processing (DLP) printing technology to construct a triply periodic minimum surface (TPMS) skeleton, and a continuous and efficient heat conduction path was successfully constructed in epoxy resin by impregnating h-BN on the skeleton surface. When the loading of h-BN was 20 vol%, the thermal conductivity of the TPMS(SiO 2)@BN/EP(BN) composites was 1.86 W/(m·K), which was 786 % higher than that of pure epoxy resin. In addition, the thermal expansion coefficient of the composites decreased by more than 70 %. At the test frequencies of 3∼10 MHz, the composites showed stable dielectric properties, and the dielectric constant was always maintained in a low range, between 3.85 and 4.15. This work has realized the transformation of the method for constructing a heat conduction path from disordered to ordered and from random to repeatable. This provides a new strategy for the selection of microelectronic packaging materials. [ABSTRACT FROM AUTHOR]

Sodium-phosphate-based glass-ceramics (GCs) are promising materials for a wide range of applications, including solid-state sodium-ion batteries, microelectronic packaging substrates, and humidity sensors. This study investigated the impact of 24 h heat-treatments (HT) at varying temperatures on Na-Ge-P glass, with a focus on (micro)structural, electrical, and dielectric properties of prepared GCs. Various techniques such as powder X-ray diffraction (PXRD), infrared spectroscopy-attenuated total reflection (IR-ATR), and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) were employed. With the elevation of HT temperature, crystallinity progressively rose; at 450 °C, the microstructure retained amorphous traits featuring nanometric grains, whereas at 550 °C, HT resulted in fully crystallized structures characterized by square-shaped micron-scale grains of NaPO3. The insight into the evaluation of electrical and dielectric properties was provided by Solid-State Impedance Spectroscopy (SS-IS), revealing a strong correlation with the conditions of controlled crystallization and observed (micro)structure. Compared to the initial glass, which showed DC conductivity (σDC) on the order of magnitude 10−7 Ω−1 cm−1 at 393 K, the obtained GCs exhibited a lower σDC ranging from 10−8 to 10−10 Ω−1 cm−1. With the rise in HT temperature, σDC further decreased due to the crystallization of the NaPO3 phase, depleting the glass matrix of mobile Na+ ions. The prepared GCs showed improved dielectric parameters in comparison to the initial glass, with a noticeable increase in dielectric constant values (~20) followed by a decline in dielectric loss (~10−3) values as the HT temperatures rise. Particularly, the GC obtained at @450 stood out as the optimal sample, showcasing an elevated dielectric constant and low dielectric loss value, along with moderate ionic conductivity. This research uncovers the intricate relationship between heat-treatment conditions and material properties, emphasizing that controlled crystallization allows for precise modifications to microstructure and phase composition within the remaining glassy phase, ultimately facilitating the fine-tuning of material properties. [ABSTRACT FROM AUTHOR]

Room temperature wafer bonding is a desirable approach for the packaging and assembly of diverse electronic devices. The formation of SiO 2 layer at the bonding interface is crucial for a reliable wafer bonding as represented by conventional bonding techniques such as hydrophilic bonding and glass frit bonding. This paper reports a novel concept of room temperature wafer bonding based on the conversion of polysilazane to SiO 2 at the bonding interface. As polysilazane is converted to SiO 2 by hydrolysis, in this work, adsorbed water is introduced to the bonding interface by plasma treatment, thereby facilitating the formation of SiO 2 at the wafer bonding interface. The experimental results indicate that the adsorbed water from the plasma treatment diffuses into the polysilazane layer and facilitates its hydrolysis and conversion. The proposed method demonstrates the successful wafer bonding at room temperature with high bond strength without interfacial voids. This technique will provide a new approach of bonding wafers at room temperature for electronics packaging. [ABSTRACT FROM AUTHOR]

Indium bumps are widely used in electronic packaging for interconnecting microelectronic devices due to their low melting point of 156.6°C, excellent bonding capabilities at room temperature, high thermal conductivity, ductility at extremely low temperatures, and ability to compensate for the mismatched coefficient of thermal expansion between different materials. However, cross-sectioning indium bumps can be challenging due to the softness and low melting point of indium. The cutting tools and techniques used must be optimized for the specific sample being analyzed, and specialized preparation techniques such as cryogenic freezing or chemical etching may be required, which can be expensive and time-consuming. Cryo-focused ion beam (FIB) is also a technically demanding process that requires careful optimization of milling parameters, multiple iterations of milling and imaging, specialized equipment, and expertise, which can make it too expensive. It should be noted that the maximum achievable crosssectional area with cryo-FIB is limited, typically in the range of hundreds of micrometers. Cryo-Argon milling is an effective technique for obtaining high-quality cross-sections of indium bump arrays and other materials prone to deformation or melting during traditional crosssectioning. This process involves freezing the sample using liquid nitrogen and bombarding it with a stream of Argon gas ion, which reduces the deformation and melting of the indium. This paper presents challenges in the sample preparation and mechanical polishing of indium micro bumps. We are showcasing an artifact: polishing particles embedded in the indiummicro bumps, hindering the revelation of their microstructure. To address this issue, we are incorporating cryo-Ar milling to remove the embedded particles from the surface of indium micro bumps. This work presents data before and after the application of cryo-Ar milling, demonstrating a significant improvement in the microstructure of indium micro bumps. Millimeter-wide, damage-free cross-sections of arrays of indium micro bumps with a clean and smooth surface were achieved through cryo-Argonmilling at 270°C. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) packaging using through-Si-via (TSV) is a key technique for achieving high-density integration, high-speed connectivity, and for downsizing of electronic devices. This paper describes recent developments in TSV fabrication and bonding methods in advanced 3D electronic packaging. In particular, the authors have overviewed the recent progress in the fabrication of TSV, various etching and functional layers, and conductive filling of TSVs, as well as bonding materials such as low-temperature nano-modified solders, transient liquid phase (TLP) bonding, Cu pillars, composite hybrids, and bump-free bonding, as well as the role of emerging high entropy alloy (HEA) solders in 3D microelectronic packaging. This paper serves as a guideline enumerating the current developments in 3D packaging that allow Si semiconductors to deliver improved performance and power efficiency. [ABSTRACT FROM AUTHOR]

With the rapid development of the microelectronics industry, industrial applications have put forward higher requirements on the efficiency and reliability of the dispenser, and the traditional piezoelectric dispenser uses ordinary spring preloading way, in this way, the dispenser is difficult to obtain a higher dispensing frequency, because of to the wear and tear between the connecting components and the subsequent response. In this paper, a new type of wire cutting π type spring is designed and manufactured, which solves the problem that traditional piezostack dispensers can not get the high operating frequency. In the structural design of π type spring, the stiffness of the reset spring is studied, and the output displacement characteristics of the reset spring are verified. Finally, we established the glue test system, and the point spray test is carried out on the fuse breaker and glycerol alcohol mixture at its operating frequency of 666 Hz. The mass of the fuse is measured by an electronic scale and its mass distribution is 3.08 mg (±2.5%). The diameter of the glycerol alcohol mixture sprayed by dispensing can reach 217.3 µm. By analyzing the mass and size of the glue point, it is verified that the piezoelectric dispenser with π-type reset spring can achieve high-frequency dispensing accuracy and small drop size. [ABSTRACT FROM AUTHOR]

Laminate substrates in advanced IC packages serve as not only the principal heat dissipation pathway but also the critical component governing the thermomechanical performance of advanced packaging technologies. A solid and profound grasp of their thermomechanical properties is of crucial importance to better understand IC packages' thermomechanical behavior. This study attempts to introduce a subregion homogenization modeling framework for effectively and efficiently modeling and characterizing the equivalent thermomechanical behavior of large-scale and high-density laminate substrates comprising the non-uniform distribution and non-unidirectional orientation of tiny metal traces. This framework incorporates subregion modeling, trace mapping and modeling, and finite element analysis (FEA)-based effective modeling. In addition, the laminates are macroscopically described as elastic orthotropic or elastic anisotropic material. This framework is first validated with simple uniaxial tensile and thermomechanical test simulations, and the calculation results associated with these two effective material models are compared with each other, as well as with those of two existing mixture models, and direct the detailed FEA. This framework is further tested on the prediction of the process-induced warpage of a flip chip chip-scale package, and the results are compared against the measurement data and the results of the whole-domain modeling-based effective approach and two existing mixture models. [ABSTRACT FROM AUTHOR]

The electronic packaging materials are important part in electronic devices and logically become main plastic composition in electronic wastes, which are over 50 million tons annually and caused serious environmental pollution. The biodegradable polymers are excellent candidates for the environment-friendly electronic packaging material, but they are hardly thermal conductive. Thus, improving thermal conductivity of the environment-friendly polymers is the key problem of the development of novel electronic packaging materials. Two typical bio-based, biocompatible and biodegradable polyesters such as poly(lactic acid) (PLA) and poly (butylene succinate) (PBS) were complexed with boron nitride nanosheets (BNNSs), which was ionic-liquid-exfoliated from hexagonal BN, to prepare a series of PBS/BNNS and PLA/PBS/BNNS composites. The chemical structure and morphology of the composites are investigated, which proved the adsorption of ionic liquid on BNNS. The experimental results show that BNNS nanosheets are evenly dispersed in PBS and PLA/PBS matrix, and the compatibility and dispersion in PLA/PBS composite matrix are improved. The thermal conductivity of the polymer composites was increased from about 0.2 W/(m*K) of PLA or PBS to 3.52 W/(m*K) of the composites with 30% of BNNS. The flame retardancy was improved as well. These performance characteristics of composite materials provide new development ideas for future electronic packaging materials and conform to the concept of green development. [ABSTRACT FROM AUTHOR]

The steady-state vibration amplitude is an important performance indicator of high-frequency ultrasonic transducers for ultrasonically assisted manipulating, machining, and manufacturing. This work aimed to develop a calculation model for the steady-state vibration amplitude of a new type of dual-branch cascaded composite structure-based ultrasonic transducer that can be used in the packaging of microelectronic chips. First, the steady-state vibration amplitude of the piezoelectric vibrator of the transducer was derived from the piezoelectric equation. Second, the vibration transfer matrices of the tapered ultrasonic horns were obtained by combining the vibration equation, the continuous condition of the displacement, and the equilibrium condition of the force. Calculation models for the steady-state vibration amplitude of the two working ends of the transducer were then developed. A series of exciting trials were carried out to test the performance of the models. Comparison between the calculated and measured results for steady-state vibration amplitude showed that the maximum deviation was 0.0221 μm, the minimum deviation was 0.0013 μm, the average deviation was 0.0097 μm, and the standard deviation was 0.0046 μm. These values indicated good calculation accuracy, laying a good foundation for the practical application of the proposed transducer.Highlights: A new type of cascaded composite structure-based high-frequency piezoelectric ultrasonic transducer is proposed. A calculation model for the steady-state vibration amplitude of the newly proposed transducer is developed. The model has good calculation accuracy and lays a foundation for the application of the proposed transducer. [ABSTRACT FROM AUTHOR]

The phase equilibria of the Ag-Al-Au ternary system and the solid-state reaction couple for the Au-xAg/Al system were investigated isothermally at 450 °C. By investigating the Ag-Al-Au ternary system and its isothermal section, this study aims to provide a clearer understanding of the phase stability and interfacial reactions between different phases. This information is crucial for designing materials and processes in electronic packaging, with the potential to reduce costs and improve reliability. There were seven single-phase regions, thirteen two-phase regions, and six three-phase regions, with no ternary intermetallic compound (IMC) formed in the isothermal section of the Ag-Al-Au ternary system. When the Au-25 wt.% Ag/Al couple was aged at 450 °C for 240–1500 h, the AuAl2, Au2Al, and Au4Al phases formed at the interface. When the Ag contents increased to 50 and 75 wt.%, the Ag2Al, AuAl2, and Au4Al phases formed at the interface. When the aging time increased from 240 h to 1500 h, the total IMC thickness in all Au-xAg/Al couples became thicker, but the types of IMCs formed at the interface did not change. The total IMC thickness also increased with the increase in the Ag content. When the Ag content was greater than 25 wt.%, the Au2Al phase was converted into the Ag2Al phase. The IMC growth mechanism in all of the couples followed a reaction-controlled process. [ABSTRACT FROM AUTHOR]

Lightweight materials with near-zero thermal expansion (NZTE) and high thermal conductivity have potential applications in precision instruments, aerospace industry and electronic packaging due to their high thermal stability. In this study, multiphase Mn 3 Zn 1-x Sn x N (MnZnSnN) with abnormal negative thermal expansion (NTE) were used to inhibit the positive thermal expansion of AlSi. The resulting composites multiphase-MnZnSnN/AlSi (mMnZnSnN/AlSi) achieved NZTE (0.40 × 10-6 °C-1) in a wide temperature range (-5–60 °C, ΔT = 65 °C). Compared with other NZTE materials, mMnZnSnN/AlSi exhibits high thermal conductivity of 60 W·m-1·K-1 and high bending strength of 211 MPa. The density of the composite is only 4.46 g/cm3, 45% lower than invar alloy. This work provides guidance for designing and fabrication of aluminum matrix materials with combined advantages of wide temperature range zero thermal expansion behavior, high thermal conductivity and high mechanical properties. [ABSTRACT FROM AUTHOR]

Polymer-metal composites are functional materials with unique physical properties, combining the high conductivity and thermal conductivity of metals with the convenient processability of polymers. In recent years, polymer-metal composites have become a hot topic at the forefront of technology. These composite materials have not only achieved technological breakthroughs in high-precision packaging for chip stacking, integrated circuits, and system integration but have also provided new insights for the development of medical sensing devices, flexible displays, and soft robotics. This article provides a systematic introduction to polymer-metal composites, summarizing their research status in the fields of electronic packaging, flexible displays, medical sensing, and electromagnetic shielding, including their working performance, application overview, and market analysis. [ABSTRACT FROM AUTHOR]

Carbon nanotube (CNT)/metal composites have attracted much attention due to their enhanced electrical and thermal performance. How to achieve the scalable fabrication of composites with efficient dispersion of CNTs to boost their performance remains a challenge for their wide realistic applications. Herein, the nanoscale dispersion of CNTs in the Stannum (Sn) matrix to boost thermal and electrical conductivity via facile ball milling techniques was demonstrated. The results revealed that CNTs were tightly attached to metal Sn, resulting in a much lower resistivity than that of bare Sn. The resistivity of Sn with 1 wt.% and 2 wt.% CNTs was 0.087 mΩ·cm and 0.056 mΩ·cm, respectively. The theoretical calculation showed that there was an electronic state near the Fermi level, suggesting its electrical conductivity had been improved to a certain extent. In addition, the thermal conductivity of Sn with 2 wt.% CNTs was 1.255 W·m−1·K−1. Moreover, Young's modulus of the composites with CNTs mass fraction of 10 wt.% had low values (0.933 MPa) under low strain conditions, indicating the composite shows good potential for various applications with different flexible requirements. The good electrical and thermal conductive CNT networks were formed in the metal matrix via facile ball milling techniques. This strategy can provide guidance for designing high-performance metal samples and holds a broad application potential in electronic packaging and other fields. [ABSTRACT FROM AUTHOR]

Interfacial adhesion and interfacial thermal resistance (ITR) are two critical factors in the interfacial force and energy transfer, but it is difficult to simultaneously achieve the desirable interfacial adhesion and ITR. Here, we overcome this challenge by fabricating an elastomer composite consisting of polydimethylsiloxane (PDMS) and micro-scale spherical aluminum (Al) fillers, which offers the high adhesion strength (1.28 MPa), high interfacial adhesion energy (528.4 J/m2), and low ITR (0.028 mm2·K/W) between the PDMS/Al elastomer composite and substrates. We further propose a quantified physical model to establish the relationship between interfacial adhesion and ITR for low phonon mismatch interfaces. This work will contribute to the development of interface science and guide the regulation of force and energy transfer at interface for wide range applications, such as electronic packaging, thermal storage, sensors, and medicine. [ABSTRACT FROM AUTHOR]

As power densification demands are placing electronic packages under greater reliability risk, the consequences of complementary or interacting stresses in producing failure are becoming increasingly significant. As such, it is important that reliability methods and package designs consider how multiplestress interactions may impact product life. Here, the coordination between a novel accelerated testing method and electronic design automation efforts has demonstrated a successful optimization approach for a wire-bonded 2D module layout combining failure mechanisms of electromigration and mechanical stressing. Utilizing custom, physics-of-failure approaches in accelerated testing, interactions can be observed in failure acceleration, which then can be incorporated into design for reliability (DfR) optimization tools. The PowerSynth 2 platform has been utilized as a DfR tool to perform a rapid reliability evaluation incorporating multistress scenarios. This work demonstrates the value added to reliability evaluation techniques when accounting for interacting failure mechanisms and suggests that next-generation power devices consider these effects in lifetime estimation. [ABSTRACT FROM AUTHOR]

Nowadays, with the increasing demands for quality and precision in microelectronic packaging, the study and prediction of droplet parameters before packaging have become increasingly important. This paper aims to derive a predictive formula for droplet volume dispensing to improve packaging quality, optimize process parameters, reduce resource waste, enhance process control, and enhance product quality and reliability. Based on the needle transfer method for ultra-microdroplet dispensing, a droplet dispensing device that meets packaging requirements is established, and precise control of droplet volume is achieved by changing the factors that affect droplet formation. The droplets obtained from experiments are analyzed using pixel extraction, and a numerical fitting method is employed to establish a droplet volume model. It is found that the pixel method is a practical approach for determining droplet volume, with an average deviation of approximately 1.85%. By conducting droplet dispensing experiments with varying initial distances, the smallest droplet volume achieved is 24.33 pL, and it is concluded that larger initial distances result in smaller droplet volumes and reduced droplet contact area. Based on the droplet dispensing experimental data obtained by varying the initial distance, mathematical predictive models for droplet volume and droplet contact area are derived. The results show that the average difference rate between predicted and actual volumes is 0.51%, and the average difference rate between predicted and actual contact areas is 0.56%. [ABSTRACT FROM AUTHOR]

The trend to integrate more electronic components in a limited space range motivates the development of advanced electronic packaging. Conventional electronic packaging is difficult to perform in stable interfacing interconnection pitch below 7 µm due to the possibility of short‐circuit problems. Herein, a kind of anisotropic conductive film (μ‐ACF) containing periodically arranged conductive microspheres for microscale pitch electrical interfacing interconnection is developed. The periodic arrangement can avert the contact of conductive microspheres, thus enabling stable interconnection with a pitch as small as 5 µm. By coating conductive microspheres with a layer of silicon insulation, the pitch can be further reduced to 3 µm, which can prevent the formation of conductive pathways between electrodes even if they come into contact with each other. Such high‐quality arrangement is achieved by lithography and capillary self‐assembly method, which is expected to be used in high‐throughput production. Thanks to the delicate design, the μ‐ACF can achieve a low contact resistance of 4.62 mΩ mm−2 and a spatial resolution of 3 µm without short‐circuit failure. The spatial resolution can be further improved by adjusting the size of conductive microspheres, which is conducive to the development of highly integrated devices. [ABSTRACT FROM AUTHOR]

The thermal conductivity of polymer composites could be improved through the orientation of fillers in specific directions. Here, a novel strategy to fabricate BN/Ag nanowires@Ni/epoxy composites (BN/Ag NWs@Ni/EP) to dynamically improve the in-plane or out-of-plane thermal conductivity of the composites in real-time by changing the direction of the magnetic field was investigated. The thermal conduction path was constructed by Ag NWs bridging between BN flakes. Ag NWs@Ni would be oriented in the in-plane or out-of-plane direction by changing the direction of the magnetic field. The out-of-plane or in-plane thermal conductivities of the composites were 0.824 and 0.723 W m−1K−1 at 40 wt% BN/Ag NWs@Ni content, and the corresponding TCEs were 429% and 359% respectively when Ag NWs@Ni was oriented in the out-of-plane or in-plane direction. Meanwhile, BN/Ag NWs@Ni/EP exhibited good mechanical and dielectric properties, which were beneficial for its industrial application in electronic packaging. This strategy provides the possibility for the applications that required the adjustment of the heat conduction direction in real-time. [ABSTRACT FROM AUTHOR]

Diamond/SiC (Dia/SiC) composites possess excellent properties, such as high thermal conductivity and low thermal expansion coefficient. In addition, they are suitable as electronic packaging materials. This study mainly optimized the diamond particle size packing and liquid-phase silicon infiltration processes and investigated a method to prevent the adhesion of the product to molten silicon. Based on the Dinger–Funk particle stacking theory, a multiscale diamond ratio optimization model was established, and the volume ratio of diamond particles with sizes of D20, D50, and D90 was optimized as 1:3:6. The method of pressureless silicon infiltration and the formulas of the composites were investigated. The influences of bedding powder on phase composition and microstructure were studied using X-ray diffraction and scanning electron microscopy, and the optimal parameters were obtained. The porosity of the preform was controlled by regulating the feeding amount through constant volume molding. Dia/SiC-8 exhibited the highest density of 2.73 g/cm3 and the lowest porosity of 0.6%. To avoid adhesion between the sample and buried powder with the bedding silicon powder, a mixed powder of α-Si3N4 and silicon was used as the buried powder and the related mechanisms of action were discussed. [ABSTRACT FROM AUTHOR]

With the development of modern science and technology, the coatings with the single function of anti-corrosion have failed to cover the special requirements in various practical applications. Particularly, the good heat dissipation effect of anti-corrosive coatings is highly demanded in some devices like electrical machinery, heat exchanger and printed circuit board. Here, a facile, eco-friendly, low-cost method is developed to fabricate thermally conductive and anti-corrosive composite coatings by mixing fillers (including boron nitride (BN) and graphene nanoplatelet (GNP)), polyvinyl pyrrolidone (PVP) and waterborne epoxy resin (WER). The hybridization of BN and GNP is used to provide more barriers to delay the penetration of corrosive medium and construct a denser heat conduction network in the composite coatings. PVP is selected as the compatibilizer to further improve the anti-corrosion and thermal conductivity of composite coatings. The effects of filler types and contents on the anti-corrosive and thermally conductive properties are researched. At the loading of 30 wt% BN and 0.5 wt% GNP, the BN@GNP/PVP/WER coating reaches the optimizing anti-corrosive ability, where the |Z| value holds around 6.5 × 109 Ω cm2 after soaking in the corrosive medium for 7 days, and the I corr and E corr values are 1.9 × 10−9 A/cm2 and -0.62742 V, respectively. Meanwhile, this coating displays great heat conduction with the thermal conductivity of 0.87 W/mK at about 30 wt% filler loading. Moreover, the electrical properties and hydrophilicity of coatings at different filler formulations are studied. It is worth noting that the higher electrical conductivity of the coatings at higher GNP content may accelerate the corrosion rate. This study provides a simple route for the design and manufacture of highly anti-corrosive and heat-conducting composite coatings, which exhibits great potential application in next-generation electronic packaging and devices. [ABSTRACT FROM AUTHOR]

Despite advances in soft, sticker‐like electronics, few efforts have dealt with the challenge of electronic waste. Here, this is addressed by introducing an eco‐friendly conductive ink for thin‐film circuitry composed of silver flakes and a water‐based polyurethane dispersion. This ink uniquely combines high electrical conductivity (1.6 × 105 S m−1), high resolution digital printability, robust adhesion for microchip integration, mechanical resilience, and recyclability. Recycling is achieved with an ecologically‐friendly processing method to decompose the circuits into constituent elements and recover the conductive ink with a decrease of only 2.4% in conductivity. Moreover, adding liquid metal enables stretchability of up to 200% strain, although this introduces the need for more complex recycling steps. Finally, on‐skin electrophysiological monitoring biostickers along with a recyclable smart package with integrated sensors for monitoring safe storage of perishable foods are demonstrated. [ABSTRACT FROM AUTHOR]