The mechanical strength of sintered nanoparticles (NPs) limits their application in advanced electronics packaging. In this study, we explore the anisotropy in the microstructure and mechanical properties of sintered copper (Cu) NPs by combining experimental techniques with molecular dynamics (MD) simulations. We establish a clear relationship between processing conditions, microstructural evolution, and resulting properties in pressure-assisted sintering of Cu NPs. Our findings reveal that pressure-assisted sintering induces significant anisotropy in the microstructure, as evidenced by variations in areal relative density and the orientation distribution of necks formed during sintering. Specifically, along the direction of applied pressure, the microstructure exhibits reduced variation in areal relative density and a higher prevalence of necks with favorable orientations. The resulting anisotropic mechanical properties, with significantly higher strength along the pressure direction compared to other directions, are demonstrated through micro-cantilever bending tests and tensile simulations. This anisotropy is further explained by the combined effects of strain localization (influenced by areal relative density) and the failure modes of necks (determined by their orientation relative to the loading direction). This work provides valuable insights into the analysis of sintered NPs microstructures and offers guidance for optimizing the sintering process.

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Low-temperature sintering technology of Ag nanoparticles is widely used in high-power electronic device packaging. Utilizing simulation methods to comprehend and control the microstructure and properties of Ag sintering materials has emerged as a prominent research area. This work uses the General Form PDE module in COMSOL to simplify the implementation of the phase field method. A two-particle model was established to explore the effects of different particle sizes and temperatures on the sintering neck of Ag nanoparticles. The two-particle model was expanded to multi-particle models and 3D models flexibly. This work presents the potential and limitations of these phase-field models, preparing for further multiphysics analysis and optimization of Ag sintering materials.@en

Resin-reinforced Ag sintering materials represent a promising solution for die-attach applications in high-power devices requiring enhanced reliability and heat dissipation. However, the presence of resin and intricate microstructure poses challenges to its thermal performance, and improvement strategies remain unclear. This work utilizes 3D FIB-SEM nanotomography to reconstruct the microstructure of this material under various process conditions. The analysis reveals that, even with an Ag volume fraction as low as 47.3%, Ag particles form a robust 3D network. Geometric tortuosity quantifies the effect of different sintering conditions on the Ag particle network in all spatial directions. Effective thermal conductivity is simulated based on realistic microstructure models. Results show a significant negative correlation between tortuosity and effective thermal conductivity. Increasing sintering temperature in Model B notably reduces tortuosity and enhances effective thermal conductivity. Sensitivity analysis underscores the dominant role of Ag volume fraction in regulating effective thermal conductivity. Finally, transient thermal impedance measurement of this material as a thin die-attach layer in actual high-power devices demonstrated its application potential. This article strives to explore the relationship between process, microstructure, and thermal properties of this material to provide a reference for further development.

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Resin-reinforced silver (Ag) sintering material is an effective and highly reliable solution for power electronics packaging. The hybrid material’s process parameters strongly influence its microstructure and pose a significant challenge in estimating its effective properties as a thin interconnect layer. This research demonstrates a novel 3D reconstruction methodology for the microstructural investigation of the resin-reinforced Ag sintering material from OverMolded Plastic (OMP) packages. Based on the reconstructed models with different sintering parameters (temperature and time), the fraction of Ag and Resin volume distribution, the connectivity of silver particles, and the tortuosity factors were estimated. A 99% connectivity of sintered Ag particles was achieved with various sintering conditions, such as 200°C for 2 hours, 200°C for 4 hours, and 250°C for 2 hours. However, coarsening of Ag particles was promoted when sintered at 250°C. Increasing the sintering time at 200°C had insignificant changes. The estimated tortuosity factor also indicated that sintering at 250°C provides the shortest heat transport path between the semiconductor die and the package substrate. In order to quantify the microstructural findings, the OMP packages’ thermal performance with different sintering conditions (temperature, time, and interconnect thickness) was experimentally assessed. Although the experimental measurements were less sensitive to the effective interface thermal resistances’, the measurement results show a good correlation with the microstructural analysis. Sintering the Resin-reinforced Ag sintering material at higher temperatures (250°C) seems to improve the package thermal performance, and increasing the sintering time at 200°C has a negligible effect.@en

The (Ca, Sr) AlSiN₃:Eu²⁺(CSASN:Eu) red phosphor is widely used to improve color rendering of high-power phosphor-converted lighting diode (pc-WLED), but it is always unstable under high temperature and high humidity environments. Therefore, the studies on the temperature and humidity resistance of red phosphors and their aging mechanism have become essential to evaluate its reliability in harsh applications. In this paper, the pressure cooker test (PCT) and 85°C&85% RH aging test were carried out for the CSASN:Eu red phosphors. And, its hydrolysis reaction-driven degradation mechanism was simulated and analyzed based on first-principle calculation, in which the optimized adsorption of simplified CaAlSiN3(CASN) and H2 O was simulated based on Density Function Theory (DFT) and the specific aging process was analyzed by the charge density difference and ab initio molecular dynamics (AIMD). The experimental results showed that the photoluminescence performance of CSASN:Eu red phosphor dropped gradually and finally disappeared under PCT aging, and its temperature-dependent degradation kinetics followed the Arrhenius model well. Meanwhile, the simulation results indicate that the CASN, reacted with H2 O when the H atoms had a tendency to approach N atoms. Both the temperature and humidity could accelerate the hydrolysis reaction rate.@en