Recent advances in isotropic conductive adhesives for electronics packaging applications

Isotropic conductive adhesives (ICAs) have recently received a lot of focus and attention from the researchers in electronics industry as a potential substitute to lead-bearing solders. Numerous studies have shown that ICAs possess many advantages over conventional soldering such as environmental friendliness, finer pitch printing, lower temperature processing and more flexible and simpler processing. However, complete replacement of soldering by ICAs is yet not possible owing to several limitations of ICAs which are mainly related to reliability aspects like limited impact resistance, unstable contact resistance, low adhesion and conductivity etc. Continued efforts for last 15 years have resulted in development of ICAs with improved properties. This review article is aimed at providing a better understanding of ICAs, their principles, performance and significant research and development work addressing the technological utility of ICAs.     

A novel, electrically protein-manipulated microcantilever biosensor for enhancement of capture antibody immobilization

This study demonstrated a microcantilever biosensor for enhancement of capture antibody immobilization. The electrically protein-manipulated, microcantilever biosensor is featured with enhanced capture antibody immobilization, miniaturization, and high sensitivity. Thanks to the electric property of biological substances in a real environment, given charged proteins can be manipulated with attraction in solution under an electric field. It is evident that higher amount of capture antibody molecules immobilized onto sensing surfaces captures or detects specific molecules, indicating greater deflection and stresses as well. This however leads to significant cost in biosensors. With the merit of MEMS technique that allows highly fabrication-compatible integration into microcantilever biosensors, sparsely distributed antibody molecules in solution are attracted in focus onto a sensing solid surface under electric fields. As the sensing element of the gold-coated, V-shaped silicon nitride microcantilever also serves as an electrode, the electric fields are applied in a channel of flowing microfluidics by locally in-plane electrodes or by a top electrode arranged for three-dimensional fields. As expected, most charged proteins distributed in solution are effectively attracted onto the sensing area within the electric fields. This improves the efficiency of capture antibody immobilization and achieves an eight-fold reduction over the necessary amount of capture antibodies without applying electric fields. With such a successful manipulation of charged proteins, the novel microcantilever biosensor exhibits efficient use of capture antibodies in solution.     

Investigations of electrically driven liquid metal flows using an ultrasound Doppler flow mapping system

This paper presents a combined experimental and numerical study of the properties of a liquid metal flow inside a cylinder driven by the application of a strong electrical current. The interaction between the electric current running through the melt and the corresponding induced magnetic field produces so-called electro-vortex flows. We consider here a configuration of two parallel pencil electrodes immersed at the free surface. Velocity measurements were performed by means of the Ultrasound Doppler method. A linear array of 25 singular transducers was used to determine the two-dimensional pattern of the vertical flow component. Numerical simulations of the magnetohydrodynamic (MHD) problem were conducted to calculate the Lorentz force, the Joule heating and the induced melt flow. Experimental and numerical results reveal a complex three-dimensional flow structure of the liquid metal flow. In particular, two pronounced downward jets are formed below both electrodes. The flow structure appears to be symmetrical with respect to two vertical cross sections being perpendicular to each other and one of the two planes contains the electrodes. The comparison between the experimental data and the numerical results shows a very good agreement.     

The design,development and assessment of electrically heated gloves used for protecting cold extremities

Abstract

The design and development of electrically heated gloves for alleviating pain in vaso-spastic disorders, such as Raynaud's disease, is described. Clinical assessment of these conditions from the temperature patterns produced by infrared thermography is discussed. The effect of electrically heated gloves on tissue perfusion in individual patients can be assessed by thermography. A ‘hot’ stress test to determine the degree of vaso-spasticity using the gloves to provide a ‘hot challenge’ has been developed and is described.     

Photo-Doped Active Electrically Controlled Terahertz Modulator

We demonstrate an electric-controlled terahertz (THz) modulator which can be used to realize amplitude modulation of terahertz waves with slight photo-doping. The THz pulse transmission was efficiently...     

基于SimulationX的电控变速液压系统仿真研究

传统的工程机械变速系统不利于减轻驾驶员劳动强度、提高操作舒适性,而电控变速系统则能很好地解决这一问题。描述了电控变速系统的原理,应用SimulationX软件对该系统压力变化进行仿真分析,总结出影响因素和规律,为系统设计提供理论依据。     

Effect of the Inside Placement of Electrically Conductive Beads on Electric Field Uniformity in a Microwave Applicator

Non-uniform heating is a major issue in microwave applications, mainly due to inherently uneven distribution of electromagnetic energy in the microwave applicator. In this work, our aim is to improve electric field distribution uniformity by utilizing microwave reflection from electrically conductive beads placed in the microwave oven. The effects of position, size, and number of electrically conductive beads on the electric field distribution were numerically investigated, and validated through water-load experiments in the cavity. It is found that uniform electric field distribution was realized to some extent by appropriate placement of electrically conductive beads; meanwhile, average electric field intensity in the microwave oven was increased.     

Electrically treated composite FILMS based on chitosan and methylcellulose blends

Films obtained from chitosan (CH) and methylcellulose (MC) can reduce environmental problems associated with synthetic packaging. The objective of the present work was to analyze the effect of an electrical field applied during drying on microstructure and macroscopic properties of films obtained with different mixtures of CH and MC.     

复杂环境中天线辐射方向图的分析

采用一致性几何绕射理论(UTD)研究了电大尺寸复杂平台中天线的辐射特性。以点源模型分析了天线受周围电磁环境影响后的辐射方向图,与自由空间方向图的对比说明了受影响后天线辐射特性的变化。与低频算法相比,本文算法有计算速度快、占用内存量很少的优点,可应用于工程中类似平台的多天线系统干扰分析。     

Improving the electrical and mechanical behavior of electrically conductive paint by partial replacement of silver by carbon black

Partial replacement of silver particles by carbon black (low cost) in electrically conductive paint was found to decrease the electrical resistivity and increase the scratch resistance of the resulting thick film, which is for use in electrical interconnections. An effective carbon black content is 0.055 of the total filler volume. By using a total solid volume fraction of 0.1969 and a silane-propanol (1:1 by weight) solution as the vehicle, a paint that gives a thick film with resistivity 2 × 10⁻³ Ω·cm has been attained.