A copper/polyimide Metal-base packaging technology

A unique substrate MCPM (Mitsubishi Copper Polyimide Metal-base) technology has been developed by applying our basic copper/polyimide technology.¹ This new substrate technology MCPM is suited for a high-density, multi-layer, multi-chip, high-power module/package, such as used for a computer. The new MCPM was processed using a copper metal base (110 × 110 mm), full copper system (all layers) with 50-μm fine lines. As for pad metallizations for the IC assembly, we evaluated both Ni/Au for chip and wire ICs and solder for TAB ICs. The total number of assembled ICs is 25. To improve the thermal dispersion, copper thermal vias are simultaneously formed by electro-plating. This thermal via is located between the IC chip and copper metal base, and promotes heat dispersion. We employed one large thermal via (4.5 mm^?) and four small vias (1.0 mm^?) for each IC pad. The effect of thermal vias and/or base metal is simulated by a computer analysis and compared with an alumina base substrate. The results show that the thermal vias are effective at lowering the temperature difference between the IC and base substrate, and also lowering the temperature rise of the IC chip. We also evaluated the substrate’s reliability by adhesion test, pressure cooker test, etc.     

MgCl2 Enhances Cluster Formation by Nanoscale Toroidal DNA Condensates

Multivalent cations can cause DNA to condense from its extended state in solution into high-density toroid-shaped particles. Developing methods to control the size and size distribution of DNA toroids is an important goal for the development of artificial gene delivery systems. Here we demonstrate that changes in salt conditions, prior to condensation by multivalent cations, can significantly affect DNA condensation. Specifically, millimolar concentrations of MgCl₂ are shown to cause the formation of toroid clusters, whereas NaCl at the same ionic strength does not.     

Smart Biopolymer-Based Nanocomposite Materials Containing pH-Sensing Colorimetric Indicators for Food Freshness Monitoring

Nanocomposite biopolymer materials containing colorimetric pH-responsive indicators were prepared from gelatin and chitosan nanofibers. Plant-based extracts from barberry and saffron, which both contained anthocyanins, were used as pH indicators. Incorporation of the anthocyanins into the biopolymer films increased their mechanical, water-barrier, and light-screening properties. Infrared spectroscopy and scanning electron microscopy analysis indicated that a uniform biopolymer matrix was formed, with the anthocyanins distributed evenly throughout them. The anthocyanins in the composite films changed color in response to alterations in pH or ammonia gas levels, which was used to monitor changes in the freshness of packaged fish during storage. The anthocyanins also exhibited antioxidant and antimicrobial activity, which meant that they could also be used to slow down the degradation of the fish. Thus, natural anthocyanins could be used as both freshness indicators and preservatives in biopolymer-based nanocomposite packaging materials. These novel materials may therefore be useful alternatives to synthetic plastics for some food packaging applications, thereby improving the environmental friendliness and sustainability of the food supply.     

基于MEMS的LED芯片封装光学特性分析

本文提出了一种基于MEMS的LED芯片封装技术,利用体硅工艺在硅基上形成的凹槽作为封装LED芯片的反射腔.分析了反射腔对LED的发光强度和光束性能的影响,分析结果表明该反射腔可以提高芯片的发光效率和光束性能;讨论了反射腔的结构参数与芯片发光效率之间的关系.最后设计了封装的工艺流程.利用该封装结构可以降低芯片的封装尺寸,提高器件的发光效率和散热特性.     

基于单片机的切纸机位移测量系统

介绍了一种基于单片机的切纸机位移测量系统。该系统以AT89C2051单片机为核心,实现了对切纸机刀具位置、进刀量以及进刀次数的实时测量,完成了多位测量结果的快速显示和测量结果的掉电保护。该系统测量准确、使用方便,大大提高了切纸机位移测量的精确度和工人的工作效率。     

GaAIAs/GaAs正面发光管的失效机理研究

研究和分析了高辐射GaAlAs/GaAs LED的退化机理。经高温加速老化,估算器件的工作寿命为10~5小时,并估算该器件的激活能为0.58eV。     

LED及其应用产品技术标准研究

介绍了LED的技术发展历程;对近年来LED产业标准化工作现状做了详细说明,分别阐述了LED器件相关标准、LED芯片和部分材料相关标准、LED显示屏相关标准、LED照明相关标准,并介绍了目前正在开展的标准研制工作;分析了我国LED产业标准化的工作特点,提出了今后工作设想.     

太阳能光伏照明系统概述

分别叙述了太阳能在荧光灯、HID灯、LED灯照明系统中的应用。为提高太阳能光伏照明系统的可靠性,介绍了太阳能光伏照明风光互补系统和太阳能光伏照明光电互补系统。并提出太阳能光伏照明系统中应注意的技术问题。     

基于Labview与单片机的LED电子屏幕

目前,LED点阵显示文字图形的控制系统,价格昂贵,功能难以扩展,使用不便。文中对LED电子屏幕的主要控制技术及其应用领域作了简要介绍,针对实际应用需要设计出一种基于Labview与单片机控制的LED电子屏幕。在提出系统整体设计方案基础上详细阐述了由Labview实现UCDOS下字库点阵数据提取方法,并设计出信息编辑与管理系统,论述了LED点阵显示原理及单片机控制系统硬件与软件设计思想。