Impact of Microstructure Evolution and Isothermal Aging on Sn-Ag-Cu Solder Interconnect Board-Level High-G Mechanical Shock Performance and Crack Propagation

The root cause of shock-induced solder joint failures in the range of 800G to 1500G is investigated. Joint stability under various shock and strain level combinations and the impact of isothermal aging on board-level shock performance were analyzed. A test vehicle was developed to obtain various combinations of shock and strain levels in a single board. Using 17 mm × 17 mm body-sized ball grid array packages on a shock test board, isothermal aging was applied prior to shock testing to determine the impact of different interface microstructures. Results revealed clear indications of a correlation between shock and strain and a trend of isothermal-aging-induced degradation. A shift in the failure locations was observed based on the interface intermetallic microstructure, and some preliminary evidence for the influence of Sn grain orientation was identified. The interrelated effects of isothermal aging, locally experienced shock and strain levels, and Sn grain orientation on mechanical shock performance are discussed.     

基于Zapmaster7/2型ESD测试仪的微电路静电测试

基于Zapmaster7/2型ESD测试仪,详细介绍了静电测试的方法、原理.静电测试的三种模型.三种模型之间的区别.在进行ESD测试时需要注意细节.     

Structural and optical properties of AIN sputtering deposited on sapphire substrates with various orientations

AIN thin films were deposited on c-,a-and r-plane sapphire substrates by the magnetron sputtering technique.The in-fluence of high-temperature thermal annealing (HTTA) on the structural,optical properties as well as surface stoichiometry were comprehensively investigated.The significant narrowing of the (0002) diffraction peak to as low as 68 arcsec of AIN after HTTA implies a reduction of tilt component inside the AIN thin films,and consequently much-reduced dislocation densities.This is also supported by the appearance of E2(high) Raman peak and better Al-N stoichiometry after HTTA.Furthermore,the in-creased absorption edge after HTTA suggests a reduction of point defects acting as the absorption centers.It is concluded that HTTA is a universal post-treatment technique in improving the crystalline quality of sputtered AIN regardless of sapphire orienta-tion.     

Self‐Assembled In‐Plane Growth of Mg2SiO4 Nanowires on Si Substrates Catalyzed by Au Nanoparticles

In‐plane growth of Mg₂SiO₄ nanowires on Si substrates is achieved by using a vapor transport method with Au nanoparticles as catalyst. The self‐assembly of the as‐grown nanowires shows dependence on the substrate orientation, i.e., they are along one, two, and three particular directions on Si (110), (100), and (111) substrates, respectively. Detailed electron microscopy studies suggest that the Si substrates participate in the formation of Mg₂SiO₄, and the epitaxial growth of the nanowires is confined along the Si <110> directions. This synthesis route is quite reliable, and the dimensions of the Mg₂SiO₄ nanowires can be well controlled by the experiment parameters. Furthermore, using these nanowires, a lithography‐free method is demonstrated to fabricate nanowalls on Si substrates by controlled chemical etching. The Au nanoparticle catalyzed in‐plane epitaxial growth of the Mg₂SiO₄ nanowires hinges on the intimate interactions between substrates, nanoparticles, and nanowires, and our study may help to advance the developments of novel nanomaterials and functional nanodevices.     

基于PLC控制的液压缸试验台的研究

文章主要分析了基于PLC控制的SHP系列单柱液压缸试验台,针对大多数液压缸试验台性能不稳定、速度不快、结构不紧凑等缺点,采用西门子PLC开发一套新型的液压缸试验台控制系统。该控制系统具有性能稳定、速度快、操作方便、使用寿命长等优点。     

影响豆腐花感官质量因素探讨

研究了大豆蛋白抽提液组成及性质、凝固条件和其它加工工艺条件下盒装豆腐花官质量的影响，并选择出较好的工艺条件。实验结果表明可以用豆腐 的凝胶强度、离析乳清、持水性等指标来评价豆腐花的感官质量。     

皮革手感的智能检测研究：Ⅱ人工神经网络在手感评定中的应用

人工神经网络具有较强的自适应模式识别能力和联想记忆能力。本文应用ＢＰ神经网络处理服装革的手感检测信号，为织物，皮革等服装材料的手感评定探索出一条新途径。     

双酯链结构对加脂性能的影响

本文主要合成了五种乙二醇双酯，两种马来酸双酯，并研究了它们对皮革的加脂性能。实验中采用了外加表面活性剂的乳化方式进行了加脂实验。从皮革对测脂的吸收，皮革撕裂强度，伸长率，抗张强度等方面进行了考察。     

双护盾盾构辅助推进液压系统设计

推进系统是盾构掘进机的一个关键部分,承担着整个盾构机掘进的关键性任务,其工作特性直接关系到盾构工程施工的正确性、可靠性和安全性。参考单护盾推进液压系统原理图,并根据双护盾推进液压系统特点,设计了双护盾盾构辅助推进液压系统,并分析和研究了其工作原理及特点。该系统采用推进缸分组控制技术进行盾构掘进方向控制及纠偏,在符合控制要求的前提下,可达到既控制成本,又简化结构的目的。利用SolidWorks软件对集成块进行三维实体建模、装配,并转化为二维CAD工程图,提高了设计效率。     

自适应小波包图像压缩感知方法

该文提出一种自适应小波包图像压缩感知方法。该方法选用小波包变换分解图像,基于数学期望和信息熵分析各个小波包系数块的属性,自适应地将其划分为低频信号、无价值信号、特殊处理信号和压缩感知处理信号等4种信号类型,再针对不同的信号类型设计对应的处理方法,适应不同特征的图像。通过此种方法,在图像压缩感知过程中,可以根据不同图像和小波包系数块自适应地选取采样值,来提高压缩感知质量。实验结果表明该文提出的自适应小波包图像压缩感知方法在相同采样值的前提下,不仅提高了图像的重构质量,同时也降低了算法的计算复杂度和所需存储空间。