Sn2.5Ag0.7CuxRE钎料时效焊点界面IMC研究

以Sn2.5Ag0.7CuxRE/Cu钎焊为研究对象,借助于扫描电镜和X衍射检测手段,研究了二硫化钼介质下时效焊点界面IMC组织结构特征及生长行为。实验结果表明:时效焊点界面Cu6Sn5IMC呈现由波浪状→扇贝状→层状的形态变化。焊点界面Cu6Sn5和Cu3Sn IMC的生长厚度与时效时间平方根呈线性关系,Cu6Sn5IMC具有较小的生长激活能、较大的生长系数。添加0.1%(质量分数)RE时,界面Cu6Sn5和Cu3Sn IMC的生长激活能最大,分别为81.74 kJ/mol和92.25 kJ/mol,对应焊点剪切强度最高。     

液态Sn3.0Ag0.5Cu钎料与Cu、Fe及Co基板界面反应研究

研究了在固定温度380℃和不同钎焊时间条件下,液态Sn3.0Ag0.5Cu钎料与Cu、Fe、Co等3种金属基板的界面反应及其界面化合物(IMC)。研究结果表明,随着钎焊时间的增加,三者界面金属间化合物的平均厚度逐渐增加。Sn3.0Ag0.5Cu/Cu界面IMC主要由Cu_6Sn_5和Cu_3Sn组成,经过长时间钎焊后界面化合物大部分是Cu_3Sn。Sn3.0Ag0.5Cu/Fe界面化合物成分是FeSn2,相比另外两种界面,IMC在钎焊过程中生长最慢,形成的厚度最小。Sn3.0Ag0.5Cu/Co界面在短时间钎焊时(1min)会出现分层现象,认为是少量CoSn2和Sn原子在靠近钎料一侧反应生成CoSn3,靠近基板一侧生成CoSn2。长时间钎焊后观察到界面化合物只有CoSn3。通过对数据拟合可得到Sn3.0Ag0.5Cu/Cu、Fe、Co 3种液固反应界面的IMC层的生长率常数分别为9.55×10-6t 0.34,1.51×10~(-6)t~(0.18),0.85×10~(-6)t~(0.45)。比较3种基板,液态Sn基钎料与Cu基板的界面反应速率最快,IMC平均厚度也更厚。     

高温下熔融SnAgCu-xTi在SiO_2表面的润湿行为

采用改良座滴法研究了高真空、800～900℃条件下熔融Sn0.3Ag0.7Cu(SAC)-xTi (x=0%、1%、3%,质量分数)在SiO_2表面的润湿行为。研究结果表明:在SAC中添加少量的Ti后,可以显著提高SAC在SiO_2表面的润湿性。当Ti浓度为3%时,Ti未被完全溶解,这是因为随着Ti浓度的增加,在Ti表面会形成一层高熔点的Sn-Ti金属间化合物,进而阻碍Ti的进一步溶解。液固界面反应产物为Ti_5Si_3和TiO,铺展动力学可用反应产物控制模型描述;在铺展过程中,快速铺展阶段首先析出Ti_5Si_3和TiO,线性铺展阶段仅析出TiO。该体系的最终润湿性取决于界面反应产物和界面上Ti-O吸附的共同作用。     

Sn-3.5Ag/Cu界面金属间化合物的生长行为研究

研究了Sn-3.5Ag无铅钎料和Cu基体在钎焊和时效过程中界面金属间化合物的形成和生长行为.结果表明,在钎焊过程中,由于钎料中存在着Cu的溶解度,界面处生成的金属间化合物存在着分解现象.因此Sn-3.5Ag/Cu界面金属间化合物层厚度与化合物层的分解有着密切关系.由于吸附作用,金属间化合物表面形成了纳米级的Ag3Sn颗粒.当钎焊接头在70,125,170℃时效时,钎焊时形成的扇贝状金属间化合物转变为层状.金属间化合物的生长厚度与时效时间的平方根呈线性关系,其生长受扩散机制控制.整个金属间化合物层和Cu6Sn5层的生长激活能分别为75.16 kJ/mol,58.59kJ/mol.     

活性剂对 Sn-0 . 65 Cu 无铅钎料的 IMC 影响

研究了几种活性剂作用下Sn-0.65Cu/Cu的扩展率及焊点界面金属间化合物(IMC)的形貌,探讨了活性剂的活性强弱与IMC厚度的关系。结果表明,不同活性剂作用下Sn-0.65Cu/Cu扩展率的大小顺序为:氢化松香>戊二酸>苹果酸>柠檬酸;在活性越强的活性剂作用下,液态钎料在Cu基板上越容易铺展,钎料的温度分布更均匀,加剧了Sn原子和溶解在液态钎料的Cu原子的热运动,Sn原子与Cu原子反应结合的概率增大,导致生成的IMC层更厚。     

电场作用下Cu/Cu_3Sn界面原子扩散行为的分子动力学模拟

电子产品中的钎焊点失效可能会引起整个产品报废,这种情况下电子元器件的回收利用对节约资源意义重大。实现电子元器件的连接界面分离是其有效再利用的前提。旨在为开发可行的连接界面分离技术提供理论参考,本工作运用分子动力学方法模拟研究了电场作用下电场方向和电场强度对Cu/Cu_3Sn界面原子扩散行为的影响。结果表明,电场方向对界面原子的扩散行为有显著影响,相同条件下施加正向电场的模型比未加电场的模型更容易发生扩散。进一步研究了正向不同电场强度下界面原子的扩散行为,发现电场强度的增加提高了界面附近Cu_3Sn侧原子的本征扩散系数,降低了Cu晶体侧原子的本征扩散系数,从而使得界面原子的扩散速率差异更加显著,产生的柯肯达尔效应更明显,有利于实现Cu/Cu_3Sn界面的分离。     

7050铝合金第二相溶解行为EI北大核心CSCD

研究热轧态7050铝合金在固溶过程中的平衡态η(MgZn2)相、T(Al2Mg3Zn3)相、S(Al2CuMg)相及含铁Al7Cu2Fe难溶相的溶解行为。采用原位扫描的组织检测方法获得上述平衡相的溶解动力学实测数据。在体扩散控制的溶解动力学模型基础上,引入曲率和界面反应对原子迁移速率的作用,建立η,T和S相溶解动力学模型。结果表明:在7050铝合金常规固溶温度(470℃)条件下,η和T相在2 min内即可完全溶解,S相保温较长的时间才能完全溶解,含Fe相不发生溶解;曲率对溶解行为影响较小,界面反应会大幅度降低溶解速率;本工作建立的η,T和S等第二相溶解动力学模型预测结果与实测结果吻合,能够为优化Al-Zn-Mg-Cu合金固溶工艺提供指导作用。     

Cu基板表面镀镍浸金保护层对无铅焊点可靠性的影响

结合Sn-3.5Ag和Sn-3.0Ag-0.5Cu两种无铅钎料研究了镀镍浸金层(Electroless Nickel Immersion Gold,ENIG)表面层对焊点界面反应以及力学性能的影响。结果表明,钎焊后在Sn-3.5Ag/ENIG/Cu界面主要生成(Ni_yCu_(1-y))_3Sn_4,在Sn-3.0Ag-0.5Cu/ENIG/Cu界面主要生成(Cu_xNi_(1-x))_6Sn_5。在Sn基钎料/ENIG(Ni)/Cu界面处生成金属间化合物的种类及形貌由焊点中Cu原子含量决定。在时效过程中,ENIG表面层中Ni层有效抑制了焊点界面处金属间化合物的生长,减缓了焊点剪切性能的下降。在钎焊过程中ENIG表面层中的Au层不参与界面反应而是进入钎料基体与Sn反应,但是在时效过程中Au原子向界面迁移并造成焊点界面金属间化合物成分和焊点剪切强度的明显变化。     

电磁场对水平双辊铸轧Ti/Al/Cu复合板界面结合强度的影响

利用水平双辊铸轧技术制备Ti/Al/Cu复合板，通过在铸轧过程中施加脉冲电场和电磁振荡场，研究不同外场对铸轧复合板界面结合强度的影响。结果表明：电磁场对铸轧过程的稳定性没有影响。施加脉冲电场和电磁振荡场后，Ti/Al界面和Cu/Al界面的扩散层厚度增加，界面结合强度显著提高。施加电磁振荡场后，在铸轧区的液穴内产生交变的电磁体积力。在电磁体积力的作用下，铝熔体内部产生震荡效应并对金属带表面进行冲刷，使金属带表面新形成的晶核脱离。此外，震荡效应使得金属带与铝熔体接触处的温度梯度降低，凝固速度减慢从而延长固-液接触时间。这些作用使得熔体在金属带表面铺展湿润更加充分，促进了原子间的互扩散，从而产生了更多的冶金结合区域并增大了冶金结合的强度。     

电镀中阴极上的金属溶解

本文研究了电沉积锡和铬时阴极金属溶解的生产实践和实验事实,提出了关于在电镀中局部阴极金属在一定条件下,以相当于阳极溶解加上自溶解的速度剧烈溶解的可能性的新见解。认为,在电镀中若阴极上的不同部位因电流密度的悬殊而存在足够大的电位差时,将在阴极上形成“局部电池”,其中在高电流密度区进行正常的电沉积,而在达不到析出电位的低电流密度区的金属,如果该种金属在电解液中是不稳定的,将以远比其在同一体系中的自溶解速度大得多的速度剧烈溶解。这可视作对电化学和电极过程动力学理论中关于外加阴极电流使溶解速度降低而称之为“阴极保护作用”这种基本情况的一种补充。作者继而提出,既然在电镀液中同一阴极上同时存在着进行阳极溶解的“阳极区”部份和进行电沉积的“阴极区”部份,应如实地把这样的阴极称作“双性电极”,而这与传统的关于电镀中“双性电极”的概念是不一致的。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Brainstorming for ISO Strategy 2016-2020

正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from