Investigation of Mechanical and Electrical Characteristics for Cracked Conductive Particle in Anisotropic Conductive Adhesive (ACA) Assembly

In an anisotropic conductive adhesive (ACA) assembly, the electrical conduction is usually achieved with the conductive particles between the bumps of integrated circuit (IC) and corresponding conductive tracks on the glass substrate. Fully understanding of the mechanical and electrical characteristics of ACA particles can help to optimize the assembly process and improve the reliability of ACA interconnection. Most conductive particles used in the ACA assembly are with cracks in the metal coating of the particles after the ACA bonding. This paper introduced the fracture analysis by applying the cohesive elements in the numerical model of the nickel-coated polymer particle and further simulating the cracks initiation and propagation in the nickel coating during the ACA bonding. The simulation results showed that the stress distribution on the nickel-coated particle with cracks was significantly different from that on the nickel-coated particle without crack, indicating that the stress analysis by taking the crack into consideration is very important for the reliability assessment of the ACA interconnection. The stress analysis of cohesive elements indicated that the cracks initiated at the central area of the nickel coating and propagated to the polar area. Furthermore, by the introduction of a new parameter of the virtual resistance, a mathematical model was established to describe the electrical characteristics of the nickel-coated particle with cracks. The particle resistance of the nickel-coated particle with cracks was found to be much higher than that of the particle without crack in the optimized bonding pressure range, indicating that it is necessary to take the crack into consideration for the particle conduction analysis as well. Therefore, the fracture analysis on the conductive particle by taking the crack into consideration could accurately evaluate the reliability of ACA interconnection and avoid serious reliability issues.     

镁钴铝类水滑石催化合成安息香甲醚

采用共沉淀法制备了镁钴铝类水滑石化合物(MgCoAl-HTLcs),并用 X 射线衍射、扫描电子显微镜、NH_3程序升温脱附等方法对 MgCoAl-HTLcs 进行了表征,并以 MgCoAl-HTLcs 为催化剂催化苯甲醛与甲醇反应合成安息香甲醚,研究了n(Mg):n(Co):n(Al)、催化剂用量、原料配比、反应温度、反应时间对合成反应的影响。表征结果显示,MgCoAl-HTLcs 的晶相完整,表面主要为弱酸、弱碱性。催化合成安息香甲醚的适宜条件为:MgCoAl-HTLcs 催化剂用量0.10 g(约为原料总质量的0.23%),n(Mg):n(Co):n(Al)=0.4:1.6:1.0,V(苯甲醛):V(甲醇)=3:50,反应温度50℃,反应时间150 min。在此条件下,苯甲醛的平衡转化率达77.49%,安息香甲醚选择性接近100%。为洁净合成安息香甲醚开辟了一条新的途径。     

炼铁生产环境负荷分析和预测研究

利用寿命周期评价的思想，计算了炼铁生产过程中的环境负荷，并分析了各因素对环境负荷的影响，运用神经网络对炼铁生产过程环境负荷进行了预测。     

日本落叶松及其在造纸领域中的应用

日本落叶松是适合在北半球广泛种植的早期速生树种 ,在我国的生长适应范围比较广 ,如今在我国华北、西北、西南和华中亚热带山区的部分地区已有种植。它在造纸领域中的应用研究已经开始 ,而且已经证实是一种很有潜力的造纸木材     

GPRS业务模型和无线网络的研究

根据GPRS业务及业务发展情况，对GPRS业务模型进行深入研究，并对GPRS无线网络进行了更深入的探讨。     

六盘山盆地与酒西盆地成藏条件对比

研究认为，六盘山盆地与酒西盆地具有相似的构造演化特征和油气成藏条件。中生代为走滑拉分盆地，发育张扭伸展断层系，新生代为陆内前陆盆地，发育扭压逆冲断裂系；中生代坳陷都发育生烃潜力较好的白垩系烃源岩，具有相似的烃源岩演化特征、生储盖组合条件和油气运聚特征。因此，分析酒西盆地油气藏分布特征和成藏控制因素，有利于认识和预测六盘山盆地的油气分布规律，以便指导下一步的油气勘探。     

双口RAM在大屏幕LED显示系统中的应用开发

双口RAM与常规RAM的最大区别是双口RAM具有两套独立的地址、数据和控制线,允许两个独立的CPU或控制器同时异步地访问存储单元,双口RAM由片内的仲裁逻辑来确定哪一侧的CPU可以访问内部RAM单元.IDT7132是2kB的标准双口RAM.文中重点介绍采用以自顶向下方法设计的基于CLD(复杂可编程逻辑器件)的大屏幕LED(发光二极管)显示系统中双口RAM的应用,并给出了系统设计方法及相关硬件电路.本设计中IDT7132双口RAM用来连接单片机信号处理模块和CPLD扫描模块.     

爆炸焊接——热轧双相不锈钢复合钢板研制

本文主要阐述了通过爆炸焊接和热轧的方法,研制成功可焊性良好的且具有较好强度、韧性与综合性能的双相耐应力腐蚀的不锈复合钢板。还将热轧与热处理的两种试验作了较全面的常规、特殊检验试验,结果完全达到使用要求。