Process and design analysis for ultrafine-pitched wiresweep elimination in advanced copper heat spreader BGA package

The semiconductor device trend for increasing functionalities and performances yet with smaller overall feature sizes presents escalating obstacles to the decreasing form factor along with demanding thermal carrying capability required at the package level. To confront this compounding issue, ultrafine-pitch wirebond interconnect coupled with thermally enhanced copper heat spreader attached to the package are introduced. However, the additional copper heat spreader thickness introduced within the package challenges the design of the package's wire, its loop height, and the molding process control to prevent wire sweeping occurrences. This study investigates the impact of different ultrafine pitched wire types, wire loop designs, copper heat spreader structures, and mold material types on eliminating device short from occurring due to the wire sweeping phenomena. A full factorial experiment is performed using an active silicon device packaged in a thermally enhanced ball grid array (BGA) test vehicle. In addition, test characterization is carried out using x-ray and multiinsertions hot/cold continuity tests. Then, a detailed failure analysis is performed by package decapsulation and scanning electron microscopy/energy-dispersive x-ray (SEM/EDX) to confirm the experimental findings. In conclusion, the study finds that for an ultrafine-pitched thermally enhanced BGA package, wire type is insignificant to reduce wire shorting occurrences. However, mold material and copper heat spreader structure using an optimized wire loop design are significant factors in eliminating wiresweep shorting phenomena. This study concludes with a wirebond interconnect and heat slug design recommended along with an improved process parameters and assembly material sets found from the experiment.     

Crystallite growth characteristics in superfine zirconia powders and compacts

Crystallite growth characteristics of coprecipitated superfine zirconia powders have been investigated. It was found that the crystallite growth in powders follows a cubic law at 800 and 1000°C; however, the crystallite size data for compacts of both Y-TZP and YSZ cannot be fitted with a traditional parabolic or cubic law, but with a linear relation between crystallite size and the logarithm of time. In addition, it was also found that the degree of agglomeration of the powders can affect the crystallite growth.     

关于加强国土资源管理的思考

全文围绕树立和落实科学发展观这一主题 ,研究和探索如何在新时期、新阶段进一步做好国土资源管理工作的新思路、新途径和新方法。提出要进一步加强国土资源宏观管理 ,更好地为甘肃省经济社会的协调、可持续发展提供保障服务。     

首钢2号高炉的技术进步

介绍首钢2号高炉大修采用的新技术、开炉操作和投产以来的生产情况。     

现场总线控制系统浅谈

简述了现场总线控制系统的结构及其显优点。现场总线控制系统的结构包括：主控器、总线接口、电源、输入／输出接点、总线电揽和终端电阻。另外对其显优点做了逐一介绍。现场总线控制系统可在工业自动化控制系统中推广应用。     

GSM技术在配电网故障自动隔离及恢复系统的应用

为了使配电网故障的隔离和恢复的通讯更加可靠、迅速、经济，设计了一种基于GSM通讯技术，借助移动通讯系统短信业务和数据业务，实现配电网故障的自动隔离与恢复的系统。该系统通过MCU采集数据，判断故障位置与故障类型，经GSM通讯模块上传主站，主站统筹全局，实现故障段的切除，非故障区的供电。阐述了系统的工作原理、硬件结构、通讯协议和软件流程。现场的实际运行情况证明数据上报通讯准确率为100％，多次模拟线路故障，根据故障点的不同，一般在2～3min内系统都能可靠的隔离故障，恢复系统。     

Hydrothermal Synthesis of Magnesium Aluminate Platelets

Magnesium aluminate (MgAl₂O₄) platelets were first synthesized by hydrothermal treatment of γ-AlO(OH) in a magnesium nitrate aqueous solution at 400°C. The platelets are 100–200 nm in width and 25 nm in thickness. The influence of temperature, the anions of the magnesium salt, the amount of magnesium salt, and precursor pH on the formation of such structure was investigated. The experimental results indicated that the anions of the magnesium salt and precursor pH could have a significant influence on the growth of MgAl₂O₄. MgAl₂O₄ formation followed the in situ transformation mechanism, which was the reason why the MgAl₂O₄ crystallites had a platelet morphology.     

地方热电联产企业发展对策的探讨

介绍了泰州热电企业的运行情况，分析了各热电厂在技术改造、扩大热用户和强化内部考核管理方面的措施，探讨了地方热电企业应采取的对策和发展思路。