Tape casting of high dielectric ceramic substrates for microelectronics packaging

The production of ceramic green tapes is integral to the production of multilayer ceramic packages and capacitors. This article presents a batch type process for producing alumina ceramic green tape down to 150 μm thickness. The process parameters relevant to the precise control of the thickness of an aluminabased ceramic tape have been investigated using a float glass tape caster. Results indicate that the cast tape thickness was dependent on the blade gap until it reached a limiting value. This limiting thickness in turn was dependent on the casting speed, with a higher speed producing thinner tapes. Optimal casting was shown to exist when the blade gap was set at or beyond the limiting value, with the casting speed the controlling factor for the final thickness.     

Characteristics of heat transfer of impingement system with swap swirl generator

This article presents the computational fluid dynamic simulation of the heat transfer characteristics induced by a swap swirl air‐jet generator on the impingement surface. The study was carried out for conventional and swap twist tape inserts of twisted ratio y = 2.93 with various swap angles (α = 30°, 60°, 90°) at a constant distance of nozzle diameter impingement plate (L = 2D). The results show that the Nusselt number of the swirl impingement air‐jet depends on the twisted tape swap angles and airflow rate. The results also showed that the swap angle of 90° gave notable uniform local heat transfer distribution compared with the typical twist tape and other swap twist tapes (α = 30°, 60°). In addition, the predicted results of the local heat transfer coefficient help explain the local turbulence intensity and generation to assist the industrial applications of swirl impingement air‐cooling jet.     

论开槽型瓦楞纸箱接合方式的选择

瓦楞纸箱因其具有良好的缓冲减震性能等诸多优点而广泛应用于包装行业。瓦楞纸箱有开槽型、套合型、折叠型3种类型,其中开槽型瓦楞纸箱可采用钉接、胶黏、胶带粘贴3种接合方式,而选用何种接合方式将直接影响企业形象和企业经济效益,应当依据包装工艺特点、包装生产工况进行选择。     

高压电力电缆阻水结构研究与分析

用试验的方法,对目前国内的高压交联聚乙烯(XLPE)绝缘电力电缆阻水结构进行了研究,分析了使用纵向阻水结构电缆的技术性能,并提出改善这种性能的工艺控制方法及建议。     

氧化锆PVA-水基流延成型工艺研究

以去离子水为溶剂,加入适量的分散剂三乙醇胺、粘结剂PVA、增塑剂聚乙二醇-400和邻苯二甲酸丁苄酯、消泡剂DF001,采用水基流延工艺成功制备了表面光滑、具有较好强度和韧性的氧化锆(TZ-5Y)薄膜.研究结果表明:聚乙二醇400和邻苯二甲酸丁苄酯配合使用可以获得较好的增塑效果;通过在15 kPa真空度下除泡20 min,同时以5 r/min搅拌,再静置2h的方法可以获得有效的除泡效果.     

一种包装机金拉线供给控制系统的设计

针对某包装机金拉线直流调速系统维护不便,金拉线经常拉断、脱槽等问题,提出了采用交流伺服驱动器和伺服电机对原系统进行改造。新的金拉线伺服控制系统采用双环控制,并对摆臂角度传感器进行调整,对伺服驱动器参数进行优化。改造后,系统运行状态良好,未发生金拉线拉断、脱槽等生产事故,证明了该设计方案的可行性及有效性。     

A Permanent Magnet Linear Synchronous Motor Drive for HTS Maglev Transportation Systems

A permanent magnet linear synchronous motor （PMLSM） for a high temperature superconducting （HTS） maglev system has been studied, including the motor structure, control strategy, and analysis techniques. Finite element analysis （FEA） of magnetic field is conducted to accurately calculate major motor parameters. Equivalent electrical circuit is used to predict the drive＇s steady-state characteristics, and a phase variable model is applied to predict the dynamic performance. Preliminary experiment with a prototype has been made to verify the theoretical analysis and the HTS-PM synchronous driving technology.     

High Temperature Superconducting Magnetic Energy Storage and Its Power Control Technology

High temperature superconducting （HTS） power inductor and its control technology have been studied and analyzed in the paper. Based on the results of simulations and practical experiments, a controlled release scheme has been proposed and verified for developing a practical HTS SMES prototype.     

内置偏心多螺旋扭带换热管的传热特性研究

通过数值模拟对内置偏心多螺旋扭带换热管的传热特性进行了计算与分析,结果表明:换热管的对流传热强度随着扭带数量的增加而提高,随着扭带扭率的减小而提高。流动阻力损失相对于空管有很大程度的提高。传热性能评价指标在湍流时普遍较低,故多螺旋扭带换热管的使用应考虑流动阻力损失的影响。     

Effect of MnO2 on the dielectric properties of Nb-doped BaTiO3-(Bi0.5Na0.5)TiO3 ceramics for X9R MLCC applications

MnO₂ and Nb₂O₅ co-doped 0.9BaTiO₃-0.1(Bi_0.5Na_0.5)TiO₃ powders with excellent dielectric properties were fabricated using a conventional solid-state reaction method and sand milling. The doping effects of various amounts of MnO₂ on the dielectric properties were investigated. The results revealed that the dielectric properties greatly depended on the concentration of MnO₂. All the ceramics met the X9R specification. The dielectric loss decreased with an increasing concentration of MnO₂. The specimen with an appropriate amount of 0.2 mol% MnO₂ exhibited the most enhanced properties: high insulation resistance (2.49 × 10¹³ Ω/cm) and improved degradation properties. Multilayer ceramic capacitor (MLCC) chips were prepared by tape casting using a 0.2 mol% Mn-doped 9010BTBNT-based ceramic powder. The capacitance of the MLCC chip was approximately 100 nF, and the dielectric loss was approximately 1.75% at room temperature. The high-temperature accelerated lifetime was over 1000 hours under 250 V (five times the working voltage) and at 230°C, indicating that the MLCC chips possess superior reliability.