Studies on various chip-on-film (COF) packages using ultra fine pitch two-metal layer flexible printed circuits (two-metal layer FPCs)

Various fine pitch chip-on-film (COF) packages assembled by (1) anisotropic conductive film (ACF), (2) nonconductive film (NCF), and (3) AuSn metallurgical bonding methods using fine pitch flexible printed circuits (FPCs) with two-metal layers were investigated in terms of electrical characteristics, flip chip joint properties, peel adhesion strength, heat dissipation capability, and reliability. Two-metal layer FPCs and display driver IC (DDI) chips with 35 μm, 25 μm, and 20 μm pitch were prepared. All the COF packages using two-metal layer FPCs assembled by three bonding methods showed stable flip chip joint shapes, stable bump contact resistances below 5 mΩ, good adhesion strength of more than 600 gf/cm, and enhanced heat dissipation capability compared to a conventional COF package using one-metal layer FPCs. A high temperature/humidity test (85 °C/85% RH, 1000 h) and thermal cycling test (T/C test, ?40 °C to + 125 °C, 1000 cycles) were conducted to verify the reliability of the various COF packages using two-metal layer FPCs. All the COF packages showed excellent high temperature/humidity and T/C reliability, however, electrically shorted joints were observed during reliability tests only at the ACF joints with 20 μm pitch. Therefore, for less than 20 μm pitch COF packages, NCF adhesive bonding and AuSn metallurgical bonding methods are recommended, while all the ACF and NCF adhesives bonding and AuSn metallurgical bonding methods can be applied for over 25 μm pitch COF applications. Furthermore, we were also able to demonstrate double-side COF using two-metal layer FPCs.     

Phenotypic and genetic antibiogram of methicillin-resistant staphylococci isolated from bovine mastitis in Korea

Staphylococcus aureus belongs to the group of major contagious mastitis pathogens, whereas the coagulase-negative staphylococci (CNS) are also capable of causing opportunistic bovine mastitis. Many of these strains are resistant to penicillin or ampicillin because of the long-term use of β-lactam antibiotics in agricultural and healthcare settings. Based on the simple and highly specific coagulase genotyping by PCR-RFLP used for discriminating among Staph. aureus strains, the relationship between phenotypic antibiogram and the polymorphism of coagulase gene was determined in this study. The staphylococci strains (835 Staph. aureus and 763 CNS) were isolated from 3,047 bovine mastitic milk samples from 153 dairy farms in 8 provinces from 1997 to 2004 in the Republic of Korea. Twenty-one (2.5%) Staph. aureus and 19 (2.4%) CNS strains were resistant to methicillin [oxacillin minimum inhibitory concentration (MIC) ≥4 μg/mL]. The mecA gene was also found in 13 methicillin-resistant Staph. aureus (MRSA) and 12 methicillin-resistant CNS (MRCNS) isolates with a significantly higher detection rate of the mecA gene in MRSA with high MIC (≥16 μg/mL) compared with those with MIC ≤ 8 μg/mL. Methicillin-resistant Staph. aureus and MRCNS were also more resistant to other antibiotics (ampicillin, cephalothin, kanamycin, and gentamicin) than methicillin-susceptible staphylococci. Among 10 different coa PCR-RFLP patterns (A to J) in 706 Staph. aureus strains, the main types were A (26.9%), B (17.0%), G (10.5%), and H (15.4%), with the frequent observation of the A and H types (6 and 10 isolates) in MRSA. This study indicates that major epidemic Staph. aureus clones may be spread between different dairy farms, and the profile of coa genotype can be applied for epidemiological investigations and control of bovine mastitis, particularly one caused by MRSA with specific prevalent coa types.     

基于超导差分加速度测量原理的微推力测量方案

随着微推进技术的快速发展,微推力器推力的测试与标定也日益困难。为实现微推力的精密测量和动态特性测试,通过分析超导重力梯度仪的差分加速度测量原理、仪器的构成和原理电路等,提出了一种基于高温超导差分加速度测量原理和SQUID检测技术微推力测量方案,其推力测量范围为10^-7-10^-2N、测量频带从直流至4Hz。根据检验质量的动力学方程和超导回路磁通量守恒方程,导出了推力与输出差分电流的传递函数,分析了影响测量的主要噪声。方案可应用于微推力的测量,并有进一步提高推力测量精度的潜力。     

High-Performance All-Solid-State Batteries Enabled by Intimate Interfacial Contact Between the Cathode and Sulfide-Based Solid Electrolytes

All-solid-state batteries (ASSBs) are considered the ultimate next-generation rechargeable batteries due to their high safety and energy density. However, poor Li-ion kinetics caused by the inhomogeneous distribution of the solid electrolytes (SEs) and complex chemo-mechanical behaviors lead to poor electrochemical properties. In this study, LiNi_0.8Co_0.1Mn_0.1O₂ (NCM) (core) – Li₆PS₅Cl (LPSCl) SEs (shell) particles (NCM@LPSCl) are prepared by a facile mechano-fusion method to improve the electrochemical properties and increase the energy density of ASSBs. The conformally coated thin SEs layer on the surface of NCM enables homogeneous distribution of SEs in overall electrode and intimate physical contact with cathode material even under volume change of cathode material during cycling, which leads to the improvement in Li-ion kinetics without the increase in solid electrolyte content. As a result, an ASSBs employing NCM@LPSCl with 4 mAh cm⁻¹ specific areal capacity exhibits robust electrochemical properties, including the improved reversible capacity (163.1 mAh g⁻¹), cycle performance (90.0% after 100 cycles), and rate capability (discharge capacity of 152.69, 133.80, and 100.97 mAh g⁻¹ at 0.1, 0.2, and 0.5 C). Notably, ASSBs employing NCM@LPSCl composite show reliable electrochemical properties with a high weight fraction of NCM (87.3 wt%) in the cathode.     

Effect of set-type yoghurt supplemented with the novel probiotic Lantiplantibacillus plantarum 200655 on physicochemical properties and the modulation of oxidative stress-induced damage

Food Science and Biotechnology - The present study developed a functional yoghurt supplemented with Lantiplantibacillus plantarum 200655 and evaluated its physicochemical properties and antioxidant...     

Effects of COVID-19 on a CMOS fabrication course: An integrated design experience

In the CMOS fabrication course described herein, the lecture component provides the theoretical background for semiconductor materials and integrated circuit fabrication processes. The laboratory component provides the hands-on experience required to fabricate and electrically characterize CMOS circuits in a one-semester format. A strong semiconductor device process design thread is achieved in the course by integrating the laboratory experience and process simulation/modeling and theoretical calculations. The risks associated with the COVID-19 pandemic have forced significant course modifications. The lecture is switched to a remote learning format, including pre-recorded content and weekly advanced Q&A sessions. The laboratory provides both in-person and remote sessions. Approved social distancing and cleaning protocols are practiced in the facility for in-person learning. Complementary remote learning resources are made available to all the students such as pre-recorded laboratory instructions, live video-based laboratory sessions, and web-based supplementary information. Compared to pre-pandemic semesters, the average students' GPA of the pandemic period has increased, attributed to larger and archived volumes of instructional material. Overall student comments related to course changes necessitated by the pandemic are mixed with both positive and negative feedback.     

Fermentative effects by probiotic Lactobacillus brevis B7 on antioxidant and anti-inflammatory properties of hydroponic ginseng

Food Science and Biotechnology - Soil-cultivation presents environmental limitations and requires considerable labor, space, and water supply. Alternatively, hydroponically-cultured ginseng (HG)...     

Beyond probiotics: a narrative review on an era of revolution

Food Science and Biotechnology - Whether knowingly or unknowingly, humans have been consuming probiotic microorganisms through traditionally fermented foods for generations. Bacteria, like lactic...     

MAC: multimodal,attention-based cybersickness prediction modeling in virtual reality

Virtual Reality - Cybersickness is one of the greatest barriers to the adoption of virtual reality. A growing body of research has focused on identifying the characteristics of cybersickness and...