Microstructure characterization of Sn-Ag solder joints between stud bumps and metal pads

The microstructure of the flip-chip solder joints fabricated using stud bumps and Pb-free solder was characterized. The Au or Cu stud bumps formed on Al pads on Si die were aligned to corresponding metal pads in the substrate, which was printed with Sn-3.5Ag paste. Joints were fabricated by reflowing the solder paste. In the solder joints fabricated using Au stud bumps, Au-Sn intermetallics spread over the whole joints, and the solder remained randomly island-shaped. The δ-AuSn, ε-AuSn₂, and η-AuSn₄ intermetallic compounds formed sequentially from the Au stud bump. The microstructure of the solder joints did not change significantly even after multiple reflows. The AuSn₄ was the main phase after reflow because of the fast dissolution of Au. In the solder joints fabricated using Cu stud bumps, the scallop-type Cu₆Sn₅ intermetallic was formed only at the Cu interface, and the solder was the main phase. The difference in the microstructure of the solder joints with Au and Cu stud bumps resulted from the dissolution-rate difference of Au and Cu into the solder.     

Oxidation-sulfidation behavior of Ni aluminide in oxygen-sulfur mixed-gas atmospheres

Oxidation-sulfidation studies were conducted on sheet samples of nickel aluminide, containing 23.5 at. % Al, 0.5 at. % Hf, and 0.2 at. % B in an annealed condition and after preoxidation treatments. Continuous weight-change measurements were made by a thermogravimetric technique in exposure atmospheres of air, a low- gas mixture, and low- gas mixtures with several levels of sulfur. Detailed scanning electron microscopy (SEM), X-ray, and electron microprobe analyses of the corrosion product scale layers were performed. The air-exposed specimens developed predominantly nickel oxide; the specimen exposed to a low- .     

镍硫化物阳极溶解的电化学研究

研究了合成镍硫化物的阳极过程。Ni_3S_2,Ni_7S_6和NiS的活性溶解伴随着生成表面产物层,其反应机理与电极电位有关。根据三种不同类型产物层生成规律的电化学研究,Ni溶出表观电子数的测定,以及产物层相组成分析和相的元素分析,认为存在三组平行反应:直接生成HSO_4~-或SO_(4-)~2的反应,生成中间硫化物的反应及生成元素硫的反应,每组反应具有不同的优势发展电位区。NiS_2阳极溶解时,基本上为生成HSO_(4-)或SO_(4-)~2的反应。     

Combined Use of Magnetic and Electrically Conductive Fillers in a Polymer Matrix for Electromagnetic Interference Shielding

The combined use of a highly magnetic filler (mumetal) in low proportion and a highly conductive filler in high proportion in a polymer matrix provides a composite material that is more effective for electromagnetic interference shielding than the use of a highly magnetic filler alone or the use of a highly conductive filler alone. Mumetal is effective (due to absorption) when it is in a composite material of DC electrical resistivity below 10 Ω cm, as provided by conductive fillers, which contribute to shielding by reflection and allow paths for eddy current.     

Anodic Electrochromism for Energy‐Efficient Windows: Cation/Anion‐Based Surface Processes and Effects of Crystal Facets in Nickel Oxide Thin Films

Anodic electrochromic (EC) oxides are of major interest as counter electrodes for smart window applications owing to their unique optical properties upon charge insertion and extraction. However, performance optimization of such oxides has been hampered by limited understanding of their EC mechanism, particularly in Li⁺‐conducting electrolytes. This paper reports on NiO_x films with 1.16 ≤ x ≤ 1.32, prepared by sputter deposition. These films are immersed in an electrolyte of lithium perchlorate in propylene carbonate, and EC properties are studied by cyclic voltammetry and in situ optical transmittance measurements. The electrochromism is significantly enhanced at large values of x. It has been found that charge exchange in Ni oxide is mainly due to surface processes and involves both cations and anions from the electrolyte, which is different from the case of cathodic EC materials such as WO₃. Whereas previous studies of Ni oxide have focused on cation intercalation, the cation/anion‐based mechanism presented here offers a new paradigm for designing and developing EC devices such as smart windows for energy efficient buildings.     

Ni颗粒增强无铅复合钎料中IMC形态之演变

通过改变钎焊工艺曲线来控制热输入量。研究了Ni颗粒周围金属间化合物(IMC)以及钎料/基板界面处IMC的形态演变。结果表明,随着热输入量由低变高,Ni颗粒周围IMC形态从向日葵状向多边形状发展,最终成为遍布整个钎料层的细碎的IMC形态;而钎料/基板界面层,因Ni颗粒的加入,出现大量的三维孔洞状IMC。从而形成了Cu元素扩散的通道,使得界面层厚度增加且呈线性增长趋势。     

高温处理对镍诱导晶化硅上的薄膜晶体管性能的影响

采用标准双栅 CMOS工艺在镍诱导非晶硅横向晶化形成的多晶硅上制造了高性能的薄膜晶体管 ,并详细研究了器件制备前高温预处理对薄膜晶体管性能的影响 .实验发现不同的温度处理 ,将引起器件性能的显著变化 .在10 0 0℃预处理温度下获得了最好的器件性能 .10 0 0℃在 NMOS管中测得的电子迁移率达 314 cm2 / (V· s) ,分别比在 110 0℃和未做高温处理下的大 10 %和 2 2 % .10 0 0℃下器件的最大开关电流比也达到了 3× 10 8.对器件的进一步重复性研究证实了上述结果的可靠性     

化学成分对ASTMA890双相不锈钢组织的影响

研究化学成分对ASTM A890双相不锈钢组织的影响,利用金相显微镜对试样进行组织观察,结合体视学定量金相,利用最小二乘法对所测得数据进行拟合,建立双相不锈钢的组织及相比例与化学成分之间的直接联系。结果表明:铬当量Creq=26.68%、镍当量Nieq=11.89%时,可使双相不锈钢的相比例达到理想的1∶1,从而获得良好的综合性能。     

金属Ni诱导横向晶化的结构及工艺进程的优化

研究了用Ni进行金属诱导横向晶化(MILC)制备大尺寸多晶硅晶粒的结构改进和工艺条件优化,改进了MILC的结构,通过在埋层氧化层上开出与衬底相连的籽晶区,减少了大晶粒多晶硅中的缺陷分布;同时在前人的基础上优化了退火温度及时间,用Secco腐蚀液观察了晶粒大小和间界分布,最后得到了质量更好的大晶粒多晶硅,其大小在70～80μm左右.同时讨论了MILC后生成的NiSi2的去除方法,成功地去除了高温退火后生成的NiSi2,大大减小了Ni在多晶硅层中的分布,保证了将MILC方法成功应用于实现深亚微米器件的研究中.     

(Ca,Sr)(Zr,Ti)O_3系抗还原高频介质瓷料的研究

采用固相合成法制备了(Ca,Sr)(Zr,Ti)O3(简称CSZT)系电容器陶瓷材料,研究了主晶相组分对所制材料介电性能的影响。结果表明:通过调整主晶相CSZT中各组分的配比,再加入适量的烧结助剂,能得到一种可在还原气氛中烧结的高频介质瓷料,该瓷料可与镍内电极共烧,其相对介电常数约为89,介质损耗(tanδ)小于5×10–4,绝缘电阻达到1012Ω,介电常数温度系数为–1 037×10–6/℃。