Quang Bang Tao

Sintered nano-silver is widely investigated as a die-attach material for next-generation power electronic modules due to its high thermal conductivity, favorable electrical performance, and stability at elevated temperatures. However, how bonding pressure and joint thickness jointly affect densification, interfacial diffusion, and mechanical reliability has not been systematically clarified, especially under the low-pressure conditions required for large-area SiC and GaN devices. In this work, nano-silver lap-shear joints with three bond-line thicknesses (50, 70, and 100 μm) were fabricated under two applied pressures (1.0 and 1.5 MPa) using a controlled sintering fixture. Shear testing and cross-sectional SEM were employed to evaluate the relationships between microstructural evolution and joint integrity. When the bonding pressure was increased from 1.0 to 1.5 MPa, more effective particle rearrangement and reduced pore connectivity were observed, together with improved metallurgical bonding at the Ag–Au interface, leading to a strength increase from 15.3 to 28.2 MPa. Although thicker joints exhibited slightly higher bulk relative density due to greater heat retention and accelerated local sintering, this densification advantage did not lead to improved mechanical performance. Instead, the lower strength of thicker joints is attributed to a narrower Ag–Au interdiffusion region, which limited the formation of continuous load-bearing paths at the interface. Fractographic analyses confirmed that failure occurred predominantly by interfacial delamination rather than cohesive fracture, indicating that the reliability of the joints under low-pressure sintering is governed by the quality of interfacial bonding rather than by overall densification. The experimental results show that, under low-pressure sintering conditions (1.0–1.5 MPa), variations in bonding pressure and bond-line thickness lead to distinct effects on joint performance, with the extent of Ag–Au interfacial interaction playing a key role in determining the mechanical robustness of the joints.

Real-time crack detection is vital for structural health monitoring in high-safety systems. This study integrates a Digital Image Correlation (DIC) system with a lightweight Convolutional Neural Network (CNN) for automated damage diagnosis. The DIC system enables high-resolution full-field strain measurement under dynamic loading, and over 1500 annotated DIC images were used to train the CNN. The model achieved 81.9% precision, 83.4% recall, and 82.1% F1-score in detecting crack initiation and propagation. Compared to traditional DIC post-processing, the proposed method provides automated, accurate, and early detection while maintaining real-time performance. The system runs efficiently on standard computing hardware without GPU acceleration, demonstrating its robustness and feasibility for industrial applications. Experimental validation on metallic specimens confirmed the method’s reliability and practical applicability in structural health monitoring.

This study investigates the effects of sintering pressure and joint thickness on the microstructure, shear strength, and fracture behavior of nanosilver joints for high-power electronic applications. Lap-shear specimens with difference joint thicknesses of 50, 70, and 90 µm were fabricated via pressure-assisted sintering under two applied pressures of 1.0 and 1.5 MPa. Mechanical testing revealed that increased sintering pressure and reduced joint thickness significantly enhanced shear strength. Fractographic and microstructural analyses showed that higher pressure improved densification, reduced porosity, and promoted the formation of continuous metallurgical bonds at the Ag/Cu interface. Despite improved bonding, interfacial delamination remained the dominant fracture mode across all conditions. Thinner joints demonstrated more uniform microstructures and higher resistance to crack initiation and propagation, whereas thicker joints exhibited incomplete sintering and stress concentrations that promoted premature failure.

Digital Image Correlation (DIC) is a crucial Non-Destructive Testing (NDT) technique widely applied in various industrial fields due to its flexibility and high accuracy. However, the performance of DIC in micro tensile-compression testing systems is often constrained by the stability and adjustability of mechanical components, particularly camera mounting systems. This study presents a specialized mechanical structure incorporating locking mechanisms, rotational axes, and sliding components, enabling precise and flexible adjustments of the camera's position and orientation. Vibration resistance was prioritized to maintain stability during testing. Experimental results demonstrated notable advancements in positioning accuracy, operational flexibility, and vibration resistance compared to conventional systems. This design offers an effective solution for laboratory and industrial applications, contributing to advancements in non-destructive material testing technologies.

PET bottles are widely used for drinking water. PET bottles’ quality depends on their thickness. The aim of this study is to find design variables and optimal parameters of the stretching blow molding (SBM) process of PET bottles in order to increase the uniformity of bottle thickness by using the simulation technique and Taguchi method. The finite element method is used to predict the results of the SBM process. The Taguchi method is performed with six variables that belong to two main factors, which are temperature positions and parison thickness. Through the analysis process, the optimal parameters are determined and verified, with a minimum objective function result of 0.000265. On the other hand, the temperature at T4 positions and the preform thickness at Th2 sections are the main influences on the uniformity of PET bottle thickness.

The clamping mechanism plays an important role in obtaining high-quality products of the injection molding process. The clamping mechanism of five-point double-toggle has been widely used for the high-speed plastics injection molding machine. The purpose of this paper is to optimize the five-point double-toggle clamping mechanism through multi-body dynamics analysis. This work also provides guidelines and a clear understanding for designing the clamping system in an injection molding machine with various clamping forces. The theoretical calculation has been handled first and then the computational model has been verified in this study. In addition, the effects of clamping forces on the main dimensions, including movable-fixed plate thickness, tie-bar diameter and average link cross-section have been investigated theoretically and numerically. The results show that the optimal design allows reaching a high force amplified ratio and that the obtained mechanism has good kinematic performance and works steadily with lower energy consumption and lower cost than the preliminary design. Moreover, the relationships between the parameters such as the critical angles of the double-toggle clamping mechanism, the ratio of force amplification and the stroke of movable mold have been found in this work. The optimized parameters will yield useful knowledge to design and manufacture the clamping mechanism of the micro injection molding machine in practice.

This paper studies the factors that cause the development of pressure ulcers (PUs) and identify the prevention of pressure ulcers (PUs). After presenting the context of pressure ulcers (PUs), we will provide a summary of the causes of pressure ulcers (PUs) formation, which were published in the literature. Then, we will study the investigative processes using numerical simulations and experiments to evaluate the factors that influence the development of pressure ulcers (PUs). The purpose of this research will provide the preventive measures and appropriate treatments for people using a wheelchair or those with disabilities. The results of this study contribute to the prediction of factors that can cause pressure ulcers to improve comfort seating and the quality of life for people with disabilities.