Multisized nanoparticles (MPs) are widely employed as electronic materials to form conductive patterns, benefitting from their excellent sintering properties and mechanical reliability. However, due to the lack of effective detection methods for the real-time sintering process, it is difficult to reveal the sintering behavior during the MPs sintering process. In this work, a molecular dynamics method is used to track the trajectory of silver atoms. The melting behavior of a single nanoparticle (SP) is first discussed. The structural evolution of equally sized nanoparticles (EPs) and unequally sized nanoparticles (UPs) during the sintering process is analyzed alongside morphology changes. It is proposed that the UPs sintering process benefits from the wetting behavior of small-sized nanoparticles on the surface of large-sized nanoparticles, and the sintering angle (θ) is proposed as an index to estimate the sintering result of UPs. Based on the works above, three basic sintering modes and one advanced sintering mode in the MP sintering process are analyzed emphatically in this paper, and the roles of different-sized nanoparticles in MPs are concluded from simulation and experimental results. This work provides theoretical support for conductive ink composition design and sintering process optimization.

Inkjet printing of high-viscosity (up to 10⁵ mPa·s) nanosilver inks is an interesting emerging technology to achieve the 3D fully printed fabrication of electronic products. The highly viscous force of the ink makes it impossible to achieve droplet ejection with the traditional piezoelectric-driven drop-on-demand inkjet method. In this study, a pneumatic needle jetting valve is adopted to provide sufficient driving force. A large number of high-viscosity inkjet printing tests are carried out, and the jetting behavior is recorded with a high-speed camera. Different jetting states are determined according to the recorded images, and the causes of their formation are revealed. Additionally, the effects of the operating pressure, preload angle, and fluid pressure on jetting states are elucidated. Furthermore, the jetting phase diagram is obtained with the characterization of the Reynolds number and the printable region is clarified. This provides a better understanding of high-viscosity inkjet printing and will promote the application of high-viscosity inkjet printing in 3D fully printed electronic products.

Ultrasonic vibration-assisted grinding (UVAG) is regarded as a superior method for the fabrication of ceramic dentures, due to its outstanding performance in hard and brittle materials’ machining. The surface roughness of dentures has a critical effect on the bonding and wear performance between dentures and natural teeth. Accomplishing the prediction of surface roughness will promote the application of UVAG in dental restoration significantly. However, the investigation about surface roughness modeling in the UVAG of ceramics is limited. In this study, a comprehensive surface roughness model was proposed with the consideration of the diamond grits’ random distribution, brittle fracture removal, and ultrasonic vibration characteristics. Based on the indentation fracture removal mechanism, the material removal process was modeled. Rayleigh’s probability density function was introduced to characterize the random distribution of the grits. Besides, the ultrasonic vibration was considered via the analysis of the single-diamond grit motion. Finally, the comprehensive model was developed with the consideration of all the diamond grits. Afterward, the verification experiments were carried out. The experimental results agreed well with the model predictions. Therefore, the comprehensive model can be applied to evaluate the surface roughness and can provide an in-depth understanding of the surface formation in the UVAG of ceramics.

The non-uniform temperature field in laser sintering critically affects conductive silver paste performance, yet its quantitative relationship with sintering mechanisms remains unclear. This study addresses this issue by proposing effective sintering temperature (T_a) and effective sintering time (S_a) as metrics to link laser parameters and sintering temperature field with sintering performance. Through full-factorial experiments, finite element simulation, and in situ thermal monitoring, it was revealed that (1) Increasing laser power and reducing laser scanning speed effectively reduce resistivity. For example, at 10 W and 0.1 mm/s, the resistivity reached 6.81 μΩ·cm, which was 88.9% lower than the value of 61.11 μΩ·cm at 2 W and 0.5 mm/s. (2) The resistivity exhibits a threshold effect in its reduction across low-power (5 W) ranges. (3) The action of laser sintering parameters on sintering performance through T_a and S_a. The resistivity decreases are correlated with T_a, exceeding the exothermic peaks (T₁ = 196 °C and T₂ = 232 °C). Unlike prior qualitative analyses, this work quantifies how non-uniform temperature fields govern sintering through T_a and S_a, offering a quantitative method to analyze the temperature field’s effect on sintering performance.

This research intends to investigate the effect and potential of the ultrasonic vibration of tools for drilling glass-fiber-reinforced plastics (GFRPs), especially with the aim of minimizing the thrust force. As an important parameter to characterize the vibration intensity, the vibration amplitude has a significant effect on the thrust force in the ultrasonic-vibration-assisted drilling (UVD) of GFRPs. It has been observed that the thrust force also influences the vibration amplitude, which may eventually result in a failure of the vibration. In this study, a method for the in-process measurement of the vibration amplitude was introduced to enable the investigation of the interaction between the thrust force and vibration amplitude in UVD. It was investigated how variations of the thrust force and vibration amplitude influence each other from holistic and individual perspectives. The critical condition was identified to ensure a sufficient ultrasonic vibration effect during drilling. Additionally, UVD experiments with different vibration amplitudes were carried out. The interaction between thrust force and vibration amplitude in UVD was revealed. It can be concluded that the combination of a moderate thrust force, low vibration amplitude reduction ratio, and high vibration amplitude increases the thrust force reduction ratio and secondly that an excessive thrust force undermines the effect of ultrasonic vibration. This provides an in-depth understanding of the interaction between vibration and thrust force in UVD, and helps to further improve the effect of ultrasonic vibration.