Sintering Of Silver Nanoparticles Research Articles

Additively manufactured conductive and dielectric 3D metasurfaces for independent manipulation of broadband orbital angular momentum

Recent developments in conductive and dielectric multi-material additive manufacturing have generated significant interest for their potential to enhance the performance of electronic devices. Lights-out digital manufacturing, a sophisticated multi-material printing technique, facilitates the seamless sintering of silver nanoparticles and acrylate inks, enabling the creation of functional electronic devices. In this study, the LDM process is utilized to prototype intricate 3D metasurface designs. A comprehensive analysis of the properties of the printed materials confirms the practicality of this multi-material printing approach. The research examines various element distributions within multi-metal layer structures, including carbon, phosphorus, oxygen, sulfur, and fluorine, to investigate the interfaces between conductive and dielectric structures. In addition, the conductivities of silver nanoparticle inks at different curing temperatures are studied to identify optimal printing conditions. Both the conductive and dielectric inks exhibit precisely controlled particle sizes and exceptional stability, which are critical for accurate additive manufacturing. Using this sophisticated printing solution, the paper presents a broadband 3D metasurface engineered to independently manipulate two distinct orbital angular momentum states in the V-band (60–70 GHz) and W-band (79–90 GHz), suitable for high-speed wireless communications. The integration of deep neural networks helps reduce the phase coupling between the frequency bands, enabling independent control of the OAM states. The structure of the dual-band metasurface features four distinct silver layers yet is fabricated on a single ultra-thin planar substrate, demonstrating its potential for applications in future wireless communication systems.

Thermally conductive silver adhesive enhanced by MXene@AgNPs with excellent thermal conductivity for thermal management applications

The Thermal Conductive Silver Adhesive (TCSA) efficiently transfers heat from electronic components to heat dissipation components, preventing overheating and extending device lifespan. Despite the effectiveness of commercial sintered nano TCSA, high production costs necessitate a more affordable, high-performance preparation method. This study presents a strategy for preparing ultra-high thermal conductivity (TC) TCSA using multidimensional thermal conductive fillers and low-temperature sintering of silver nanoparticles (AgNPs). MXene@AgNPs particles are synthesized via in-situ reduction of AgNPs on MXene surfaces. These particles, combined with silver microflakes (AgMFs) as primary fillers and epoxy (EP), undergo low-temperature heat treatment to form the AgMFs-MXene@AgNPs/EP composite. Characterization and computational models show that filler-filler interface thermal resistance (ITRf-f) is critical for TC. Adding MXene alone is insufficient, but using MXene@AgNPs particles as secondary fillers allows AgNPs to interconnect fillers, effectively reducing the ITRf-f. The resulting composite achieves an ultra-high TC of 65.51 Wm−1K−1 with 63 wt% total filler content (60 wt% AgMFs, 3 wt% MXene@AgNPs). This study advances the development of low-cost, high-performance TCSA for thermal management applications.

Conductive Inks with Chemically Sintered Silver Nanoparticles at Room Temperature for Printable, Flexible Electronic Applications

Conductive inks composed of chemically sintered silver (Ag) nanoparticles were prepared. The enlargement of particle size was accompanied by the increase in conductivity of the Ag nanoparticle ink. The resistance of the as-prepared and sintered Ag nanoparticles printed on different substrates was measured, and results showed that the formulated conductive ink works best on glossy paper. This is due to the compatibility of the conductive ink with the porosity and surface roughness of the glossy paper. The conductive ink formulation was also used as printer ink, and results showed a decrease in resistance as the printing pass was increased.

Impact Analysis of Microscopic Defect Types on the Macroscopic Crack Propagation in Sintered Silver Nanoparticles

Impact Analysis of Microscopic Defect Types on the Macroscopic Crack Propagation in Sintered Silver Nanoparticles

Optimization of heating profile for superconductor joint performance made by resistive joule heating process

The long-term heating (>60 min) of second generation high temperature superconductor (2G HTS) tape-joints at temperatures above 200 °C leads to the continuous deterioration of their superconducting properties. Previously, we proposed a resistive Joule heating process with a short heating time (∼10 min) that exhibited beneficial critical current (Ic), retention percentages (84–99 %), and joint resistances (74–697 nΩ cm2) in four independent experiments.In this study, we investigated two heating rates and three tape-joint areas. The results show that for the samples with different tape joint areas, the critical current retention percentages (97–100 %) and uniformity of specific joint resistances (82–272 nΩ cm2) were significantly improved at a high heating rate of ∼30 °C/min. The sintering of silver nanoparticles and oxidation characteristics of the copper stabilizers were observed using transmission electron microscopy, scanning electron microscopy, and Raman spectroscopy to elucidate the effect of different heating profiles. This study opens new avenues for improving the quality of 2G HTS tape joint processes for ultrahigh magnetic field applications.

Elucidation of the capillarity-promoted sintering of silver nanoparticles produced by a spark ablation vapor source

Through the spark ablation method, high purity, spherical silver nanoparticles (Ag NPs) with a size of 5 ± 3 nm are prepared. A solvent-assisted sintering method is developed to modulate the sintering structure and properties of the as-prepared Ag NPs. The effects of the solvents terpineol, polyethylene glycol-200, 1,2-propanediol, and ethylene glycol are explored. The results show that treatment with ethylene glycol causes the shear strength of the sintered Ag NPs at 180, 220, 260, and 300 °C to significantly improve from 0, 3.7, 22.1, and 64.6 MPa to 37.1, 56.1, 76.6, and 93.1 MPa respectively. Additionally, the size and number of voids in the sintered structure are significantly reduced. From the perspective of the capillary pressure induced by the solvent during sintering, a correlation between low solvent wettability and small agglomerate size of the Ag NPs is revealed, which reasonably explains the structure and properties of the sintered Ag NPs that were treated with different solvents. The spark ablation and solvent-assisted sintering methods provide a new approach for the fabrication and structure–property design of metal NPs for electronic applications.

Connecting the macroscopic and mesoscopic properties of sintered silver nanoparticles by crystal plasticity finite element method

The stress–strain response of sintered silver nanoparticles (AgNP) materials is precisely characterized in order to adapt for numerical analysis and rational design of electronic packaging structures in this study. A framework of crystal plasticity finite element method (CPFEM) is established based on the mechanism of crystal plastic deformation to describe the mesoscopic structural influence of grain evolution on the macroscopic properties of sintered AgNP materials. Material parameters of crystal plasticity are defined and initial orientations are randomly assigned for sintered AgNP grains. To calibrate the mesoscopic mechanical properties of sintered AgNP by the proposed CPFEM, the results of CPFEM simulations and uniaxial tensile tests subjected to different strain rates and temperatures are compared in terms of the stress–strain curves as the critical macroscopic characteristics. The predicted stress and deformation distributions in the polycrystalline structure demonstrate that the significant inhomogeneity of stress and deformation is caused by the different grain orientations of sintered AgNP. Furthermore, we elucidate the fracture mechanism influenced by the temperature and strain rate and also the effect of initial crystal orientation on the plastic strain of sintered AgNP. This study sheds light on the morphology design of sintered AgNP with optimized mechanical properties and fatigue resistance.

Statistical effects of pore features on mechanical properties and fracture behaviors of heterogeneous random porous materials by phase-field modeling

Heterogeneous materials with randomly distributed pores are ubiquitous, such as sintered silver nanoparticles, concrete materials, 3D printed polymers, and natural bones. Recent experimental investigations have revealed that porosity and also pore-related geometries (size, number, shape, distribution and alignment) have significant impacts on the mechanical behavior of random porous materials. However, existing studies focus on the porosity effect while ignoring other pore features such as pore size and pore shape. Our research is dedicated to a computational framework for generating isotropic/anisotropic random porous materials using Gaussian random fields with stochastic pore size and shape factor and addressing the mechanical properties and behavior of brittle fractures using a fracture phase-field model with a preferred degradation function. Sintered silver nanoparticles with typical randomly distributed pores, as representative porous materials, are chosen for their promising applications in emerging fields such as power electronics and wearable devices. In order to emphasize the effect of pore size and shape, 420 random samples with a fixed porosity were generated to discuss the stress–strain response during fracture and to establish statistical relationships between pore feature distributions and mechanical properties such as Young's modulus, UTS, and average historical energy. Our findings suggest that the statical attributes of the pore sizes and shape factors significantly affect the material performance related to the mechanical properties and fracture behavior, which could give a better understanding of the random porous materials and guide reliability-based material design optimization.

Temperature Estimation during Pulsed Laser Sintering of Silver Nanoparticles

During the thermal sintering of metal nanoparticles (NPs) the process temperature plays the most important role in the outcome of the sintering results and the selection of a suitable substrate. Here, temperature calculation during pulsed laser sintering of silver (Ag) nanoparticles (NPs) inkjet-printed on glass substrates is presented. During the pulsed laser sintering of Ag NPs, a minimum line resistivity less than twice the bulk silver resistivity was obtained within around 52 s under a laser power of 276 mW. The temperature field during the pulsed laser sintering of Ag NPs was estimated via a three-dimensional numerical model in which a temperature-dependent thermal conductivity of Ag NPs was adopted. An algorithm for treating the thermal conductivity of the heated Ag NPs in a region by a previous laser shot was devised for the improvement of the temperature field estimation. A maximum temperature of approximately 204 °C over the Ag NPs line was obtained with a 276 mW laser power and a scanning speed of 135 μm/s.

Computational analysis model of intense pulsed sintering of silver nanoparticles

Intense pulsed light sintering uses a high-power pulsed xenon lamp to release large amounts of energy and promote the growth of sintered necks between nanoparticles in additive manufacturing. However, the process results in poor stability of the sintering effect on conductive patterns and easily damages the target materials. An analysis model was developed in this study to investigate the mechanism of intense pulsed sintering. The sintering process was divided into pre-sintering and formal sintering. In pre-sintering, the conductive pattern is described by the porous volatilization model based on Darcy's fluid equation to calculate the solvent phase change volatilization state, whereas a multi-scale analysis model was established for the formal sintering process. First, a molecular dynamics model was used to analyze the sintering state of nano-silver clusters in a variable temperature field to calculate the time-varying parameters. Second, from a finite element model, the intense pulsed sintering temperature field was constructed for different sintering parameters and applied to the two-phase flow model of sintering nano-silver particles to calculate the sintering process state of nano-silver particles. The relationship between the intense pulsed sintering parameters and the sintering state was revealed, thus providing a reliable theoretical basis for the sintering process to improve sintering stability.

Characteristic Effects of Pulse Overlapping During Pulsed Laser Sintering of Silver Nanoparticles

Characteristic Effects of Pulse Overlapping During Pulsed Laser Sintering of Silver Nanoparticles

The Effect of Current Supply Duration during Stepwise Electrical Sintering of Silver Nanoparticles

We studied the effect of current supply duration at final-step currents during the stepwise electrical sintering of silver (Ag) nanoparticles (NPs). Ag NPs ink was inkjet-printed onto Eagle-XG glass substrates. Constant final-step currents of 0.4 and 0.5 A with various time intervals were applied to the printed samples. The final-step current of 0.5 A damaged the line at a comparatively shorter time duration. On the other hand, the lower final-step current of 0.4 A prevented the line damage at longer time durations while producing comparatively lower Ag NPs specific resistance. The minimum specific resistances of the printed samples sintered at 0.4 and 0.5 A were 3.59 μΩ∙cm and 3.79 μΩ∙cm, respectively. Furthermore, numerical temperature estimation and scanning electron microscope (SEM) analysis were conducted to elaborate on the results. The numerical temperature estimation results implied that the lower estimated peak temperature at the final-step current of 0.4 A helped prevent Ag NP line damage. The SEM micrographs suggested that a high surface porosity—caused by higher sintering peak temperatures—in the case of the 0.5 A final-step current resulted in a comparatively higher Ag NP line-specific resistance. This contribution is a step forward in the development of Ag NP sintering for printed electronics applications.

Importance of dislocations in ultrasound-assisted sintering of silver nanoparticles

For acoustic softening of solid materials, it has been suggested that the enhancement of dislocation motion by ultrasonic irradiation plays some role. In order to study the role of dislocations in ultrasound-assisted sintering of silver nanoparticles, numerical simulations are performed using a model developed from the solid-state sintering model by Kraft and Riedel coupled with the models of evolution of mobile and immobile dislocations and that of vacancies. It has been clarified that the most important effect of ultrasound is the reduction in the pore size, which results in the lager saturated density. In addition, the time-averaged densification rate increases by ultrasound irradiation because the increase in the magnitude of the plastic strain rate at the compression phase of ultrasound overwhelms the decrease at the rarefaction phase due to a much larger bulk viscosity at the rarefaction phase caused by the nonlinear effect. The relative density is saturated after about 3 min under ultrasound irradiation, which agrees with the experimental result. The total dislocation density does not increase by ultrasound irradiation under the present condition as the mobile dislocations are immediately immobilized due to the small initial grain size of 20 nm. For the increase in dislocation density, initial grain size should be larger than about 10 μm irrespective of the presence or absence of ultrasound.

Improved thermal conductivity of poly(dimethylsiloxane) composites filled with well-aligned hybrid filler network of boron nitride and graphene oxide

Polymer composites have attracted considerable attention due to their easy processability, low cost, and various applications. However, intrinsic poor thermal, electrical properties of polymer always have been the bottlenecks of multifunctional technical development. In this study, fabrication of low dielectric loss and highly thermal conductive composites was investigated through hybridization of silane-treated reduced graphene oxide (rGO) and boron nitride (BN), sintering of silver nanoparticles (AgNPs) on the surface of two-dimensional fillers, and infiltration of poly(dimethylsiloxane) (PDMS). The well-ordered filler structure was achieved by aligned BN on the rGO surface. The aligned PDMS/BNA-SrGOA composites, which form heat transfer paths along the filler orientation of two-dimensional BN and GO, exhibited high thermal conductivities of 10.91 and 1.27 W/mK according to in-plane and through-plane direction in a 1:2 ratio of BN and rGO. In addition, the dielectric loss was decreased by interaction with BN compared to that with only the rGO composites. Finally, the treatment of a silane coupling agent on the rGO surface reduced the interface resistivity between the filler and matrix, which reinforced the thermal, electrical, mechanical properties.

Research on sintering process and thermal conductivity of hybrid nanosilver solder paste based on molecular dynamics simulation

Nanosilver solder paste has become one of the widely materials in the field of electronic packaging due to its excellent thermal conductivity and mechanical properties. This paper considers the rapid sintering technology characteristics, the sintering processes of the same diameters and hybrid diameters nanosilver solder paste are simulated from the microscope perspective based on the molecular dynamics simulation theory. By tracing the atoms' trajectories on the surface of the nanosilver particles, the dominant sintering mechanism is obtained. Then, the thermal conductivity of the sintered silver nanoparticles is calculated by the equilibrium molecular dynamics method. The simulation results show that the densest sintered silver layer with the highest thermal conductivity is obtained when the diameter ratio of hybrid nanosilver balls is around 1:1.4, which provides a technical reference for the future proportioning of nanosilver solder paste.

Insights into the high-sulphur aging of sintered silver nanoparticles: An experimental and ReaxFF study

In high power electronics packaging, sintered silver nanoparticle joints suffer from thermal-humidity- electrical-chemical joint driven corrosion in extreme environments. In this paper, we conducted aging tests on sintered silver nanoparticles under high-temperature, high-humidity, and high-sulphur conditions. The results show that: (1) the sample under the dry high-sulphur conditions at a high temperature exhibited the highest degree of sulphidation; (2) Reactive force field (ReaxFF) molecular dynamics (MD) simulations of sintered silver nanoparticle sulphidation revealed the sulphidation layer was formed by silver atoms upward migration. This work paves the way for further investigation on sintered silver nanoparticles corrosion considering multi-physics coupling effects.

Laser-induced shock wave sintering of silver nanoparticles on flexible substrates

With the ever-increasing demand for lightweight, small, flexible, and portable devices, solving problems such as film cracking, delamination, and substrate damage has become a key issue in the direct fabrication of metal nanoparticle thin films on flexible substrates. In this work, we propose a method to sinter silver nanoparticles mechanically on heat-sensitive polymer substrates using a laser-induced shock wave generated by pulsed-laser ablation of a sacrificial layer. Physical mechanisms involved in silver nanoparticle sintering and properties of the sintered film were experimentally analyzed. Sintering of silver nanoparticles occurred predominantly by surface necking through solid-state atomic diffusion. In terms of density and electrical conductivity of the sintered films, the method shows substantially better sintering performance than typical sintering methods. Under optimal condition, near-full-density silver films were produced with an electrical resistivity as low as ~2.7 μΩ·cm. Consequently, this work demonstrates that the proposed laser-induced shock pressing technique has good potential for the fabrication of high-density metal films and patterns on heat-sensitive flexible substrates with exceptional film properties.

Features of the formation of conductive films during thermal and laser sintering of silver nanoparticles stabilized by an ethoxylated carboxylic acid

Silver nanoparticles (Ag NPs) of ~ 6 nm in size were synthesized by the reduction of silver 2-[2-(2-methoxyethoxy)ethoxy]acetate by benzyl alcohol acting both as the solvent and as the reducer. The as-synthesized Ag NPs were dispersed in a mixture of nontoxic solvents with different boiling temperatures (butanol and propylene glycol ethers) to prepare ink. The ink was spin-coated on polyimide films and processed with thermal and laser sintering. After thermal sintering, the silver films have a non-uniform structure and contain many voids, causing their resistivity to be quite high (28 µΩ×cm). Laser sintering of the Ag NPs inks spin-coated on a polyimide film using a fiber laser operating at a wavelength of 1.064 µm in a pulse-periodic mode results in a uniform film structure, almost without voids, with a lower resistivity of 2.3 µΩ×cm. Laser sintering in this case is a promising method to fabricate conductive patterns on various substrates, including polymer flexible ones.

Facile fabrication of integrated microfluidic SERS substrate by femtosecond laser sintering of silver nano particles

Surface Enhanced Raman Scattering (SERS) has emerged as a very powerful analytical tool due to its unique capability of molecular fingerprint detection. Integration of SERS onto microfluidic platforms will enable the study of liquid samples especially for point-of-care medical diagnostics and Biology. Fabrication of uniform, reproducible and large area microfluidic SERS substrates are essential in order to get consistent results especially while dealing with samples in liquid form. Femtosecond Laser Micromachining as a tool is being extensively used in various fields as it gives consistent and reproducible results. In the present work, we integrated SERS substrate onto a fused silica based microfluidic channel by employing Femtosecond Laser Sintering of Silver Nano Particles. Due to the inherent advantages of Femtosecond Laser Micromachining, uniform and large area SERS substrates were fabricated to study the SERS of liquids. The parameters suitable for fabrication of SERS substrates in a microfluidic channel are discussed. The Average Enhancement Factor of the SERS signals is correlated with the Femtosecond Laser Sintering parameters. As a proof of concept, we have demonstrated the SERS studies of 1 mM Rhodamine-6G (in water) solution. Reproducibility of the SERS results was verified and an Average Enhancement Factor of 104 is achieved. This facile fabrication add nuances to the glass based microfluidic channels to perform SERS measurements.

Simulation of silver nanoparticles sintering at high temperatures based on theoretical evaluations of surface and grain boundary mobilities

In this study, we deal with simulation of mass transport by evaporation/condensation and grain boundary motion during sintering of silver nanoparticles (Ag NPs) at high temperatures. To overcome a lack of experimental data, we derive from thermodynamics a method for evaluating specifically the grain boundary mobility of silver in the relevant range of temperature. The two sintering mechanisms are then implemented in a program dedicated to simulation of evolving surfaces shaped by driving forces. Pairs of Ag NPs with different size ratios and an aggregate of polydisperse Ag NPs are simulated to investigate the microstructural changes under high temperature sintering.