http://yetl.yabesh.ir/yetl1/handle/yetl/19053 Mon, 14 Sep 2026 18:05:51 GMT 2026-09-14T18:05:51Z https://localhost:443/yetl1/bitstream/id/184273/ http://yetl.yabesh.ir/yetl1/handle/yetl/19053 http://yetl.yabesh.ir/yetl1/handle/yetl/4316895 Investigation of the High-Vacuum Au/Si Eutectic Wafer Bonding Process for MEMS Resonators Zha, Kaixiang; Wang, Shuo; Zhao, Junyuan; Niu, Bo; Hong, Yiyi; Zhu, Yinfang; Yang, Jinling Abstract. This study demonstrates a reliable wafer-level Au/Si eutectic bonding technique suitable for hermetic packaging of MEMS resonators with small cavities (≤0.01 mm3). By optimizing the Au-Si eutectic bonding process, including outgassing/bonding time, heating/cooling rates, and the incorporation of a Pt barrier layer, significant improvements in bonding quality were achieved. The hermetically sealed cavities exhibited a vacuum level below 2 Pa, a shear strength exceeding 56.4 MPa, and an average helium leak rate of 2.85 × 10−9 atm·cc/s. Furthermore, the quality factors (Q factors) of packaged cantilevers increased substantially from 400 to over 60,000, indicating effective mitigation of air damping. These results suggest that this bonding technique holds considerable promise for the development of high-performance, small-volume, and cost-effective MEMS devices. Thu, 01 Jan 2026 00:00:00 GMT http://yetl.yabesh.ir/yetl1/handle/yetl/4316895 2026-01-01T00:00:00Z http://yetl.yabesh.ir/yetl1/handle/yetl/4316828 A Physics-Informed Adaptive Segmentation Fitting Method for Transient Thermal Test Analysis Zhu, Haorui; Jian, Maoliang; Yang, Lianqiao Abstract. Transient thermal testing is a crucial technique for characterizing the thermal properties of semiconductor devices, but measurement noise often compromises its accuracy. Conventional square-root fitting (SRF) methods emphasize early-time details at the expense of global fidelity, whereas exponential fitting (EF) methods capture global behavior but sacrifice early-time physical detail. In this paper, we propose a physics-informed adaptive segmentation (PIAS) approach. By analyzing the differential characteristics of the thermal response, our method automatically identifies the physical transition region where heat flow evolves from quasi-one-dimensional to three-dimensional diffusion, thereby constraining the segmentation point without relying on empirical judgment. A composite objective function—incorporating global fitting error and derivative continuity constraints—is globally optimized via particle swarm optimization (PSO). Simulation and experimental results demonstrate that PIAS overcomes the inherent limitations of traditional techniques. Under strong noise conditions (signal-to-noise ratio as low as 45 dB), it outperforms leading commercial software by reducing the noise-induced error in total thermal resistance from 4.48% to just 0.15%, while achieving subsecond computation per fit. PIAS enables high-precision, fully automated transient thermal analysis with significant engineering relevance. Thu, 01 Jan 2026 00:00:00 GMT http://yetl.yabesh.ir/yetl1/handle/yetl/4316828 2026-01-01T00:00:00Z http://yetl.yabesh.ir/yetl1/handle/yetl/4316740 Characterization of Fatigue Performance for Bulk Epoxy Molding Compound in Sustained High Temperature Exposure Up to 1 Year Aging Lall, Pradeep; Zhang, Yunli Abstract. The reliability of electronic devices is significantly influenced by the fatigue failure of packaging materials under prolonged high-temperature exposure. Epoxy molding compounds (EMCs) are widely used to encapsulate and protect semiconductor devices against contaminants, corrosion, and thermomechanical stresses. In automotive underhood environments, electronic packages experience sustained high temperatures, which can lead to EMC fracture, enabling moisture and contaminants to penetrate and accelerate failure. Despite the critical role of EMCs in electronic reliability, limited research exists on their fatigue resistance. This study investigates the fatigue performance of two developmental EMCs intended for automotive applications under prolonged exposure to 100 °C for up to 360 days. Fracture toughness and stress–life relationships are analyzed, and the effects of aging on inelastic work per cycle are evaluated. S–N curves are reported, demonstrating the applicability of the Basquin equation in modeling elastic fatigue behavior. By systematically examining the fatigue characteristics of EMCs, this study provides valuable insights for enhancing the reliability of electronic packaging materials in harsh automotive environments. Thu, 01 Jan 2026 00:00:00 GMT http://yetl.yabesh.ir/yetl1/handle/yetl/4316740 2026-01-01T00:00:00Z http://yetl.yabesh.ir/yetl1/handle/yetl/4316640 Characterization of Non-PFAS Underfill Behavior Under Harsh Operating Conditions Lall, Pradeep; Kasturi, Madhu; Janowsky, Leyton; Davis, Edward Abstract. Per- and polyfluoroalkyl substances, or PFAS for convenience, are a group of synthetic chemicals that were first produced in the 1940s and are being widely used across a variety of industries. Their unique properties, including their resistance to heat, water, oil, and stains, are what make them so useful. Due to their remarkable persistence in the environment, they are often simply known as “forever chemicals.” Because PFAS have been found in water sources, soil, and wildlife, they are hard to eliminate from the environment and can accumulate in our bodies over time. They have also been linked to a variety of health issues, such as immune system dysfunction, developmental issues, and some cancers. More stringent regulations and the elimination of PFAS from consumer products and industrial applications are called for by governments, government agencies, and special-interest groups. In this paper, the influence of high-temperature storage at various temperatures and hygrothermal exposure under varied conditions on the development of non-PFAS underfill characteristics is examined. The samples are placed in high temperature ranges from 100 °C to 150 °C and kept in the humidity chamber for the absorption of moisture under 85 °C/85% relative humidity condition. Then, the underfill samples are tested under dynamic mechanical analyzer (DMA) with three-point bend mode. The oxidation layer developed after exposure of samples under a harsh environment is studied under polarized optical microscopy. Thu, 01 Jan 2026 00:00:00 GMT http://yetl.yabesh.ir/yetl1/handle/yetl/4316640 2026-01-01T00:00:00Z