锡膏固晶与铝片焊线工艺应用于功率及分立器件封装

对于许多单双芯片的MOSFET封装于像SC-70、SOT-2X、TO-252、SOP-8L、TSSOP-8L、QFN等形式的器件来说,标准的固晶工艺如:银浆、软焊料加上金丝、铝丝焊的工艺方法已不能同时满足连续的成本压缩要求和提升封装器件本身的性能。2年来,通过与当地著名的客户和设备供应商的合作,晶微科技有限公司已经开发出了一款新的高温锡膏快速固化机,用以实现这种锡膏固晶的工艺。这种工艺与银浆工艺相比在产品阻抗值及产品因热而导致阻抗漂移问题方面能够得到极好的结果;比起软焊料固晶工艺,在产能和设备应用效率上优越很多,这种新的工艺能带来了相当积极的影响。换言之,这种工艺能把固晶产量相应地提高60%～70%,以非常低的生产成本实现了多种多样的固晶封装形式。     

基于ADS1100高精度智能测力计

文中介绍基于串行A/D转换器ADS1100的新型高精度智能测力计的开发,阐述它的硬件结构和软件程序.该测力计将作用于传感器的力转换成电压值,经A/D转换后用单片机进行处理,其结果通过LCD显示,并具有超荷报警、电压欠压报警、掉电进入低功耗模式等功能.     

博士后简介

博士后简介陈树强陈树强男，１９６０年出生于福建省福州市．１９８２年毕业于厦门大学物理系，获理学学士学位；１９８２～１９８４年在化工部晨光化工研究院从事塑料测试技术研究；１９８７年在西北工业大学获工学硕士学位；１９８７～１９８９年在南昌航空工业学院任教...     

贮氢负极的电化学交流阻抗特性研究

通过试验测得金属氢化物电极的电化学交流阻抗谱（ＥＩＳ）,经过分析得到该电极的等效电路图。为了分析电极在不同状态下的阻抗及不同种类电极的阻抗,ＥＩＳ被用于其分析：（１）不同带电态的电极;（２）不同集流体电极;（３）不同化成态的电极。试验结果表明：（１）随放电深度的增加,电荷传递阻抗Ｒ７有先减小后增大的趋势,温伯格阻抗对应电导逐渐减小;对此进行了理论分析;（２）泡沫镍在电极中起到的集流作用不一定明显优于冲孔镍带,但可能由于镍的电催化作用,能减小电极反应的电子转移步骤阻抗;（３）以充放电方式的电化学化成主要是减小电荷转移阻抗,而对温伯格阻抗无明显影响。     

Dynamic rheological behavior and morphology of poly(trimethylene terephthalate)/poly(ethylene octene) copolymer blends

The dynamic rheology and morphology of poly(trimethylene terephthalate) and maleic anhydride grafted poly(ethylene octene) composites were investigated. A specific viscoelastic phenomenon, that is, a second plateau, appeared at low frequencies and exhibited a certain dependence on the content of elastomer particles and the temperature. This phenomenon was attributed to the formation of an aggregation structure of rubber particles. The analyses of the dynamic viscoelastic functions suggested that the heterogeneity of the composites was enhanced as the particle content or temperature increased. The microstructural observation by scanning electron microscopy confirmed that maleic anhydride could react with the end groups of poly(trimethylene terephthalate) to form a stable interfacial layer and result in a smaller dispersed‐phase particle size due to the reduced interface tension. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Allelopathy of Phenolics from Decomposing Stump-Roots in Replant Chinese Fir Woodland

The change of total phenolic content in decomposing Chinese fir stump-roots of different ages in replant woodland and its effects was investigated. The total phenolic contents in stump-roots decreased with increasing stump-root age. The order of total phenolic content in different parts of stump-roots was, root > stump heartwood > stump sapwood. Phenolics released from Chinese fir stump-roots reduced the growth of fir seedlings. The growth of Chinese fir seedlings was negatively correlated with total phenolic content in stump-roots that had been added to the soil. Extracts of Chinese fir stump-roots inhibited fir seed germination. The results, based on paper chromatography and HPLC, revealed that eight phenolic compounds were present in the Chinese fir stump-roots.     

铬天青S分光光度法测定液氯中含铝量

研究了液氯介质中,铬天青Ｓ作显色剂分光光度法测微量铝的新方法。铝含量在０．０５～０．５ｍｇ／ｌ范围内遵守比尔定律。应用此法测定液氯中铝含量,结果满意。     

The preparation of heparin-like hyperbranched polyimides and their antithrombogenic,antibacterial applications

1,3,5-Tris(4-aminophenoxy) benzene (TAPOB) and 2,2-bis [4-(3,4-dicarboxyphenoxy) phenyl] propane dianhydride (BPADA) were used to synthesize an amino-terminated hyperbranched polyimide (AM-HBPI). Then, the 2-methacryloyloxyethyl phosphorylcholine-modified hyperbranched polyimide (HBPI-MPC) was obtained through the graft modification of MPC onto AM-HBPI by Michael addition. The infrared spectroscopy and X-ray photoelectron spectroscopy spectra showed MPC molecules were successfully grafted onto the HBPI molecules. The HBPI-MPC films exhibited slightly decreased thermal stabilities with 5% weight loss temperature in the range of of 418–483?°C in nitrogen, compared with the pure HBPI film. With the increase of MPC grafting amount, the static water contact angles decreased from average 84.0° of the pure HBPI film to average 45.0° of the HBPI-MPC film with 20% MPC. Meanwhile, the increased surface roughness of the HBPI-MPC films increased the contact areas with the platelets, enhancing their anticoagulant efficiency. The number of platelet adhesion declined and the shape of platelet changed from flat to round. The recalcification times grew from average 300?s of pure HBPI to average 551?s of the HBPI-MPC film with 20% MPC, indicating improved anticoagulant properties and biocompatibility. Bacterial adhesion test also demonstrated the number of bacterial adhesion was significantly reduced and antibacterial properties were improved. Thus, the HBPI-MPC films have great application prospects as biomedical anticoagulant materials.

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