Interface Reaction Between Electroless Ni–Sn–P Metallization and Lead-Free Sn–3.5Ag Solder with Suppressed Ni3P Formation

The voids formed in the Ni₃P layer during reaction between Sn-based solders and electroless Ni–P metallization is an important cause of rapid degradation of solder joint reliability. In this study, to suppress formation of the Ni₃P phase, an electrolessly plated Ni–Sn–P alloy (6–7 wt.% P and 19–21 wt.% Sn) was developed to replace Ni–P. The interfacial microstructure of electroless Ni–Sn–P/Sn–3.5Ag solder joints was investigated after reflow and solid-state aging. For comparison, the interfacial reaction in electroless Ni–P/Sn–3.5Ag solder joints under the same reflow and aging conditions was studied. It was found that the Ni–Sn–P metallization is consumed much more slowly than the Ni–P metallization during soldering. After prolonged reaction, no Ni₃P or voids are observed under SEM at the Ni–Sn–P/Sn–3.5Ag interface. Two main intermetallic compounds, Ni₃Sn₄ and Ni₁₃Sn₈P₃, are formed during the soldering reaction. The reason for Ni₃P phase suppression and the overall mechanisms of reaction at the Ni–Sn–P/Sn–3.5Ag interface are discussed.     

IMC Growth at the Interface of Sn–2.0Ag–2.5Zn Solder Joints with Cu,Ni, and Ni–W Substrates

Growth of intermetallic compounds (IMC) at the interface of Sn–2.0Ag–2.5Zn solder joints with Cu, Ni, and Ni–W substrates have been investigated. For the Cu substrate, a Cu₅Zn₈ IMC layer with Ag₃Sn particles on top was observed at the interface; this acted as a barrier layer preventing further growth of Cu–Sn IMC. For the Ni substrate, a thin Ni₃Sn₄ film was observed between the solder and the Ni layer; the thickness of the film increased slowly and steadily with aging. For the Ni–W substrate, a thin Ni₃Sn₄ film was observed between the solder and Ni–W layer. During the aging process a thin layer of the Ni–W substrate was transformed into a bright layer, and the thickness of bright layer increased with aging.     

Impact of Ni concentration on the intermetallic compound formation and brittle fracture strength of Sn–Cu–Ni (SCN) lead-free solder joints

Cu₆Sn₅ and Cu₃Sn are common intermetallic compounds (IMCs) found in Sn–Ag–Cu (SAC) lead-free solder joints with OSP pad finish. People typically attributed the brittle failure to excessive growth of IMCs at the interface between the solder joint and the copper pad. However, the respective role of Cu₆Sn₅ and Cu₃Sn played in the interfacial fracture still remains unclear. In the present study, various amounts of Ni were doped in the Sn–Cu based solder. The different effects of Ni concentration on the growth rate of (Cu, Ni)₆Sn₅/Cu₆Sn₅ and Cu₃Sn were characterized and compared. The results of characterization were used to evaluate different growth rates of (Cu, Ni)₆Sn₅ and Cu₃Sn under thermal aging. The thicknesses of (Cu, Ni)₆Sn₅/Cu₆Sn₅ and Cu₃Sn after different thermal aging periods were measured. High speed ball pull/shear tests were also performed. The correlation between interfacial fracture strength and IMC layer thicknesses was established.     

Cruciform Pattern of Ni5Zn21 Formed in Interfacial Reactions Between Ni and Sn–Zn Solders

A unique cruciform pattern was observed for the Ni₅Zn₂₁ phase formed in both liquid-state and solid-state interfacial reactions between rectangular Ni substrate and both Sn–9 wt.%Zn and Sn–80 wt.%Zn. In these reactions, the Ni₅Zn₂₁ layers were uniformly formed at the interfaces. However, the Ni₅Zn₂₁ layer ruptured near the edges of the rectangular Ni substrate and the reaction layers were discontinuous. The cruciform pattern was closely correlated with linear growth of the Ni₅Zn₂₁ phase and the tensile stress generated because of the edge geometry. The liquid-state reaction between Sn–9 wt.%Zn and Ni resulted in a crescent shape at the edges because Ni₅Zn₂₁ growth was enhanced, owing to its linear growth. Most importantly, cruciform pattern formation also occurred in the solid-state reactions between Sn–Zn and Ni. In the liquid-state reaction between Sn–80 wt.%Zn and Ni, a porous structure and unusually fast growth at the acute-angled corner were observed. The reactions between Cu and Sn–9 wt.%Zn and Sn–80 wt.%Zn were also studied. For these, in contrast, parabolic growth was observed. The reaction layer was uniformly formed at the corners of the Cu substrate, leading to complete coverage.     

Nanosilver-Promoted Trimetallic Ni–Co–Mn Perovskite Fluorides for Advanced Aqueous Supercabatteries with Pseudocapacitive Multielectrons Phase Conversion Mechanisms

Aqueous supercapacitors (ASCs) and batteries (ABs) have drawn great attention as promising energy storage devices. However, the key issues of limited energy density of ASCs and inferior power density/poor cycling life of ABs discourage their further application. Herein, a new concept of advanced aqueous supercabatteries (ASCBs) realized by nanosilver-promoted trimetallic Ni–Co–Mn perovskite fluorides (K_1.0Ni_0.4Co_0.2Mn_0.4F_3.2 (KNCMF-10^#)/Ag(37%), denoted as 10^#/Ag(37%)) electrode materials is proposed, integrating with the respective superior specific power/cycling behavior and energy density of ASCs and ABs. A pseudocapacitance-dominated multielectrons phase conversion mechanism of the 10^#/Ag(37%) electrode materials can be deduced by ex situ characterizations and electrochemical techniques. The constructed ASCBs by matching 10^#/Ag(37%) cathode with activated carbon (AC)/Bi(17%) anode achieve great energy density without sacrifice of power density and cycling life in wide temperatures, benefiting from the synergistic energy storage superiority of ASCs and ABs containing capacitive, pseudocapacitive, and Faradaic response in electrochemical processes. Overall, this work highlights the new idea of nano-Ag-promoted trimetallic Ni–Co–Mn perovskite fluorides with a pseudocapacitive multielectrons phase conversion mechanism as a new pop star for advanced ASCBs, showing a great significance in the context of designing advanced electrode materials and in-depth understanding of their complicated charge storage mechanisms for aqueous electrochemical energy storage systems.     

Ni3N–CeO2 Heterostructure Bifunctional Catalysts for Electrochemical Water Splitting

Developing low-cost and high-efficient bifunctional catalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is greatly significant for water electrolysis. Here, Ni₃N-CeO₂/NF heterostructure is synthesized on the nickel foam, and it exhibits excellent HER and OER performance. As a result, the water electrolyzer based on Ni₃N-CeO₂/NF bifunctional catalyst only needs 1.515 V@10 mA cm⁻², significantly better than that of Pt/C||IrO₂ catalysts. In situ characterizations unveil that CeO₂ plays completely different roles in HER and OER processes. In situ infrared spectroscopy and density functional theory calculations indicate that the introduction of CeO₂ can optimizes the structure of interface water, and the synergistic effect of Ni₃N and CeO₂ improve the HER activity significantly, while the in situ Raman spectra reveal that CeO₂ accelerates the reconstruction of O_V (oxygen vacancy)-rich NiOOH for boosting OER. This study clearly unlocks the different catalytic mechanisms of CeO₂ for boosting the HER and OER activity of Ni₃N for water splitting, which provides the useful guidance for designing the high-performance bifunctional catalysts for water splitting.     

Lattice strains and magnetic properties evolution of Ni doped rod-like cobalt–manganese ferrite

Co_0.5Mn_0.5–xNi_xFe₂O₄ (0.0≤x≤0.3) precursor is obtained by solvothermal method at 160 °C in glycol–water. Cubic Co_0.5Mn_0.5–xNi_xFe₂O₄ is obtained by calcining the precursor from 600 °C to 800 °C in air. The precursor and its calcined products are characterized by thermogravimetry and differential scanning calorimetry, X-ray powder diffraction, scanning electron microscopy, and vibrating sample magnetometer. A high-crystallized rod-like Co_0.5Mn_0.5–xNi_xFe₂O₄ with a cubic structure is obtained when the precursor is calcined at 800 °C in air for 2 h. Lattice parameters decrease with the increase of Ni²⁺ addition amount. The magnetic properties of Co_0.5Mn_0.5–xNi_xFe₂O₄ depend on Ni²⁺ doped amount and calcination temperature. Co_0.5Mn_0.3Ni_0.2Fe₂O₄ obtained at 800 °C has the highest specific saturation magnetization value, 63.51 emu/g. However, Co_0.5Mn_0.3Ni_0.2Fe₂O₄ obtained at 600 °C has the highest coercivity value, 1204.02 Oe.     

Low temperature fabrication of Ni–P metallic patterns on ITO substrates utilizing inkjet printing

A low temperature process to fabricate high resolution metallic lines on indium tin oxide (ITO) substrates using inkjet printing and subsequent electroless plating is described in this study. In this method, a thermo-sensitive (styrene-co-NIPAAm)/Pd (St-co-NIPAAm/Pd) nanoparticle-based ink was printed onto ITO substrates to create patterned catalytic sites, where nickel is subsequently deposited by electroless plating to form metal lines with desired width and conductivity. The inkjet printing variables such as droplet spacing and printing voltage, as well as the Ni electroless deposition variables such as deposition time and temperature were systematically investigated to obtain the optimum parameters. The adhesion of the deposited Ni–P coating to the ITO substrate was evaluated by a scotch tape test method. Optical microscope observation shows that a continuous pattern was formed with a printing voltage of 37 V and a droplet spacing of 50 μm. The irritating coffee ring effect was significantly suppressed by raising the substrate temperature to 50 °C and increasing the electroless plating temperature to 75 °C. High-resolution conductive metal lines can be easily and successfully fabricated using our method, which shows good potential for preparing the metallic lines as front or back electrodes in solar cells.     

Effect of Isothermal Aging on the Long-Term Reliability of Fine-Pitch Sn–Ag–Cu and Sn–Ag Solder Interconnects With and Without Board-Side Ni Surface Finish

The combined effects on long-term reliability of isothermal aging and chemically balanced or unbalanced surface finish have been investigated for fine-pitch ball grid array packages with Sn–3.0Ag–0.5Cu (SAC305) (wt.%) and Sn–3.5Ag (SnAg) (wt.%) solder ball interconnects. Two different printed circuit board surface finishes were selected to compare the effects of chemically balanced and unbalanced structure interconnects with and without board-side Ni surface finish. NiAu/solder/Cu and NiAu/solder/NiAu interconnects were isothermally aged and thermally cycled to evaluate long-term thermal fatigue reliability. Weibull plots of the combined effects of each aging condition and each surface finish revealed lifetime for NiAu/SAC305/Cu was reduced by approximately 40% by aging at 150°C; less degradation was observed for NiAu/SAC305/NiAu. Further reduction of characteristic life-cycle number was observed for NiAu/SnAg/NiAu joints. Microstructure was studied, focusing on its evolution near the board and package-side interfaces. Different mechanisms of aging were apparent under the different joint configurations. Their effects on the fatigue life of solder joints are discussed.     

Monodisperse and 1D Cross-Linked Multi-branched Cu @ Ni Core–Shell Particles Synthesized by Chemical Reduction

We report on a two-step wet chemical route for producing Cu@Ni core–shell particles with multiple needle-like branches on the surface. Using the usual synthesis process, urchin-like Ni shells were formed on the surface of spherical Cu cores and monodisperse particles were obtained. Under the direction of a static magnetic field, one-dimensional, well-aligned Cu@Ni particles were assembled through cross-linking the branched Ni shells. The monodisperse Cu@Ni particles show stable and uniform field electron emission, having a low turn-on field of 3.3 V/μm and a large current density of 1 mA/cm² under an applied field of about 5.33 V/μm.     

中国Ni—Cd和Ni—MH电池的进展

1.概述 中国Ni-Cd和Ni-MH电池的生产始于五十年代,当时主要生产有极板盒开口式电池。虽然这是一种古老的产品,但具有结构坚实、寿命长和价格低的特点。直到现在还在一些工业领域中应用。 从八十年代中期开始,中国的Ni-Cd电池工业有了快速的发展,新的生产厂家增多,开发出多种类型的极板,生产出各种类型的Ni-Cd蓄电池。老厂也进行了大规模     

Mechanical reliability of Sn-rich Au–Sn/Ni flip chip solder joints fabricated by sequential electroplating method

In this study, we evaluated the mechanical reliability of Sn-rich, Au–Sn/Ni flip chip solder bumps by using a sequential electroplating method with Sn and Au. After reflowing, the average diameter of the solder bump was approximately 80 μm and only a (Ni,Au)₃Sn₄ intermetallic compound (IMC) layer was formed at the interface. Due to the preferential consumption of Sn atoms within the solder matrix during aging, the solder matrix was transformed sequentially in the following order: β-Sn and η-phase, η-phase, and η-phase and ε-phase. In the bump shear test, the shear force was not significantly changed despite aging at 150 °C for 1000 h and most of the fractures occurred at the interfaces. The interfacial fracture was significantly related to the formation of brittle IMCs at the interface. The Sn-rich, Au–Sn/Ni flip chip joint was mechanically much weaker than the Au-rich, Au–Sn/Ni flip chip joint. The study results demonstrated that the combination of Sn-rich, Au–Sn solder and Ni under bump metallization (UBM) is not a viable option for the replacement of the conventional, Au-rich, Au–20Sn solder.     

电火花腐蚀制备Ni粉

采用电火花腐蚀的方法制备了Ni粉。通过X射线衍射、扫描电子显微镜和激光粒度分析仪对不同电流制备的Ni粉的组成、形貌、粒度及其分布进行了分析,结果表明,颗粒的相组成绝大部分是金属Ni,颗粒呈球状,40 A加工条件下小颗粒的比例最大。并且探讨了电火花腐蚀制备颗粒的机理。     

化学镀Ni/浸Au

概述了化学镀 Ni/浸镀 Au 表面精饰工艺和阻挡层的诸功能,确定了具有优良阻挡层功能的最小化学镀 Ni 层厚度为2.0μm。     

印制板化学镀Ni/Au

本文通过介绍安美特公司(Atotech)化学镀Ni/Au工艺流程,实验和总结药液的性能,列举在生产实践中一些故障的现象和原因,从而达到更有效地、更好地控制工艺参数和维护工艺的稳定,以便为生产服务。     

Ni/Au产量最大化

概述了化学镀Ni/浸镀Au精饰工艺程序、工艺控制和解决产品缺陷的方法,以求PCB化学镀Ni/浸镀Au精饰的产量最大化。