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The purpose of this paper is to comparatively investigate the microstructure and interfacial intermetallic compound (IMC) layer of Cu/SACPG/Ni and Cu/SAC0307/Ni solder joints after thermal aging.

The specimens were thermally aged at 150°C for 0, 24, 168 and 500 h. The microstructure and morphology of the interface IMC layer were observed by means of scanning electron microscope. The IMCs and the solder bump surface were analyzed by EDS. Moreover, the thickness of IMC layer was measured by using the image analysis software.

The morphology of IMC of Cu/SAC0307/Ni solder joint was consistent with that of the Cu/SACPG/Ni joint, which indicates that the addition of P and Ge had little effect on the IMC formation. The needle-like (Cu,Ni)6Sn5 was formed at the interface of solder/Ni solder joints. Meanwhile, the tiny particles inferred as Ag3Sn phase attached to the surface of (Cu,Ni)6Sn5. The growth rate of IMC layer of the Cu/SACPG/Ni joint was smaller than that of Cu/SAC0307/Ni joint with aging time increasing, which means the addition of trace P and Ge can slightly suppress the diffusion rate of the interfacial IMC.

There are no previous studies on the formation mechanism of the IMC layer of SAC0307 solder alloys with P and Ge addition.

This paper aims to select parameters such as temperature thermal stability and temperature coefficient of resistance (TCR) for Ni–P resistive alloys obtained by electroless metallization. Ni–P alloys are used in the manufacture of precision resistors characterized by TCR in the range of ± 10 ppm/K. The correlation of the technological parameters with the electrical properties of resistors enables the accurate prediction of the TCR resistors.

The Ni–P layers were obtained by a continuous process at about 373 K in a solution with the acidity of pH = 2 and then dried for two hours at 393 K. Subsequently, the Ni–P layer was stabilized for two hours in the temperature range of 453-533 K. Resistance was measured with an accuracy of 1 mΩ. TCR was determined with an accuracy of 1 ppm/K in the temperature range 298-398 K. In the next stage of the investigation, the increase in TCR of the Ni–P alloy was correlated with the increase in stabilization temperature. Scanning electron microscope images of the alloy surface were studied to assess grain sizes and to relate the average grain size with TCR values of resistive alloys. The X-ray diffraction analysis was performed to determine the crystallization temperature of Ni–P alloy.

The conducted investigation showed that the TCR increase in alloy is a linear function of stabilization temperature in the temperature range in which transition from amorphous phase to crystalline phases did not occur. TCR increase in Ni–P alloy arises from the increase of average size of grains resulting in decrease of scattering of electrons on grain boundaries. The analysis of alloy composition in chosen fragments of surface shows inhomogeneity growing with decreasing analyzed surface dimensions which proves that, before the stabilization, the structural arrangement of alloy is inconsiderable.

The obtained results are the first attempt to relate the morphology of surface with TCR of alloy and demonstration of linear dependence between an increase in TCR of amorphic Ni–P alloy and stabilization temperature of resistive layer. Such correlations are not described in available literature.

The paper aims to present a research on the impact of the stabilization process of a thin metallic layer (Ni-P) produced on a ceramic surface (Al₂O₃) by means of electroless metallization on its electric parameters and structure. On the basis of the research conducted, the existence of a relationship between resistance (R) and the temperature coefficient of resistance (TCR) of the test structure with a Ni-P alloy-based layer and the temperature of stabilization was proposed.

Metallic Ni-P layers were deposited on sensitized and activated substrates. Metallization was conducted in an aqueous solution containing two primary ingredients: sodium hypophosphite and nickel chloride. The concentration of both ingredients was (50-70) g/dm³. The process lasted 60 min, and the metallization bath pH was kept at 2.1-2.2, whereas the temperature was maintained at 363 K. The thermal stabilization process was conducted in different temperatures between 453 and 623 K. After the technological processes, the resistance and TCR of the test structures were measured with a micro ohmmeter. The composition and the morphology of the resistive layer of the structures examined was also determined.

The dependence of the resistance on the temperature of the stabilization process for the temperature range 553 to 623 K was described using mathematical relationships. The TCR of test resistors at the same thermal stabilization temperature range was also described using a mathematical equation. The measurements show that the resistive layer contains 82.01 at.% of nickel (Ni) and 17.99 at.% of phosphorus (P).

The results associate a surface morphology Ni-P alloy with the resistance and TCR according to temperature stabilization. The paper presents mathematical relationships that have not been described in the literature available.

This paper aims to investigate the structural, corrosion and the study of tribocorrosion features of the AA7075 aluminum alloy with and without the application of electroless Ni-P/Ni-B duplex coating with a thickness of approximately 40 microns.

Surface characterization of the samples was made by structural surveys (light optic microscope, scanning electron microscopic examinations and X-ray diffraction analyses), hardness measurements, corrosion and tribocorrosion tests.

Results of the experiments showed that upper Ni-B coating deposited on the surface of first Ni-P layer by duplex treatment caused remarkable increment in the hardness, corrosion resistance and tribocorrosion performance as compared to the AA7075 aluminum alloy.

This study can be a practical reference and offers insight into the effects of duplex treating on the increase of hardness, corrosion and tribocorrosion performance.

The ability to produce a uniform composition, high corrosion resistance with a hard coating layer during the electroless coating techniques are mainly based on the plating bath composition. The complexing agent is one of the most important components that control the coating layer properties. This paper aims to investigate the effect of the glycine as a complex agent on the surface and corrosion properties of Ni-P and Ni-P/Al₂O₃ electroless coating.

In this study, the effect of glycine as a complexing agent on the final surface and corrosion properties of the Ni-P and Ni-P/Al₂O₃ coatings has been investigated. The surface morphology and composition of the coated samples were investigated by scanning electron microscope (SEM) imaging and energy dispersive x-ray spectroscopy (EDS) analysis. Linear polarization scan and electrochemical impedance spectroscopy techniques were used to investigate the corrosion properties of the coating layer.

The results clarify that, glycine has a remarkable effect on the porosity content of Ni-P and Ni-P/Al₂O₃. It was found that increasing of glycine concentration results in higher porosity content in the coating layers. Also, the porosity in the coating layers minimizes the protectability of the coating against corrosion. The results also show that adding nano-alumina (Al₂O₃) to the coating path has improved the corrosion properties by decreasing the porosity in the coating layer. The scanning electron microscope (SEM) images showed that the concentration of glycine affects the content and distribution of alumina nanoparticles embedded in the coating layer. Also, it was observed that using a high concentration of glycine (0.4 M glycine), the alumina tends to agglomerate and the final alumina content in the coating was decreased.

The present study reveals that the quality of the final coating plays a major role in the corrosion performance of the steel substrate. The coating quality can by improve remarkably by optimization of the complexing agent used in the plating bath, to minimize the porosity involve in the coating layer.

The purpose of this paper is to investigate the deposition of uniform, adherent and crack‐free Ni‐P thin films on carbon fibres using the electroless deposition technique.

Before applying the electroless process, the carbon fibre surfaces must be subjected to several treatment processes to remove the organic binder, etching and surface metallization. The surface morphology of the Ni‐P coatings was assessed using a scanning electron microscope (SEM). The chemical compositions of Ni‐P layers were identified by energy dispersive X‐ray analysis (EDS). The bond strength of the coated layer was determined by measuring the electrical resistance at the fibre/coating interface. The magnetic properties of the fibres were estimated using a hysteresis diagram. The tensile performance of single fibres coated by Ni‐P has been investigated with respect to coating thickness.

Pre‐treatment processes are used to improve the adhesion of Ni‐P layers and to obtain homogeneous coatings. The influence of plating parameters (temperature, pH and time) on the coating thickness of the Ni‐P layer was investigated. It was found that the coating thickness increased as the pH value, plating time and the temperature of the bath increased. The results revealed that a complete and uniform Ni‐P coating on fibre could be obtained at optimum conditions 85°C, pH 6, for 60 min, and the results indicated that the P content in the electroless deposit is approximately 3.4 wt%. The tensile strength values are improved significantly after coating and increased by 3‐5 times with increasing of coating thickness from 0.3 to 2 μm.

The results presented in this work are an insight into understanding of the deposition and adherence of Ni‐P thin films on carbon fibre using the electroless technique and behaviour of the coated fibre.

The purpose of this paper is to characterize electrical parameters of amorphous Ni‐P resistive layers used for fabrication of precise resistors.

Ni‐P resistive layers were produced by the chemical process in water solution using Ni^2 + and H₂PO₂⁻ ions. The paper presents the results of the studies concerning the influence of bath acidity and conditions of thermal stabilization on the structure and temperature coefficient of resistance of Ni‐P alloy.

The temperature coefficient of resistance of amorphous Ni‐P layers was found to depend significantly on the parameters of chemical metallisation process. It was stated that the changes of through‐casing resistivity versus the acidity of technological solution have roughly parabolic characteristics.

In this paper, it was at first explained how the changes of the structure of Ni‐P resistive layers depend on their temperature coefficient of capacitance.

The purpose of this paper is to investigate the hardness and elastic modulus on interfacial phases formed between Sn-3.5Ag solder and Ni-18 at. % W alloy film by nanoindentation. It has been found that a ternary amorphous Sn-Ni-W layer formed below Ni3Sn4 IMC at the interface. In this study, mechanical properties of the IMC formed between SA solder and Ni-18 at. % W film after six times reflows were performed by nanoindentation.

The characterization was carried at 25°C, and 100 indents were generated. The elastic modulus and hardness were investigated.

The results showed that hardness of Ni3Sn4 IMC was higher than amorphous Sn-Ni-W phase. A slight bigger indent was observed on the Sn-Ni-W layer compared with that on the Ni3Sn4 IMC. Lower topographical height in the Sn-Ni-W layer indicated that the Sn-Ni-W phase was softer compared with the Ni3Sn4 IMC. The lower hardness and soft Sn-Ni-W phase is significantly related to the amorphous structure that formed through solid-state amorphization.

There are no publications about the indentation on the interfacial between the Ni-W layer and the Sn-Ag solder.

This paper aims to present the possibility of computer-aided technology of chemical metallization for the production of electrodes and resistors based on Ni-P and Ni-Cu-P layers.

Based on the calculated parameters of the process, test structures were made on an alumina substrate using the selective metallization method. Dependences of the surface resistance on the metallization time were made. These dependencies take into account the comparison of the calculations with the performed experiment.

The author created a convenient and easy-to-use tool for calculating basic Ni-P and Ni-Cu-P layer parameters, namely, surface resistance and temperature coefficient of resistance (TCR) of test resistor, based on chemical metallization parameters. The values are calculated for a given level of surface resistance of Ni-P and Ni-Cu-P layer and defined required range of changes of TCR of test resistor. The calculations are possible for surface resistance values in the range of 0.4 Ohm/square ÷ 2.5 Ohm/square. As a result of the experiment, surface resistances were obtained that practically coincide with the calculations made with the use of the program created by the authors. The quality of the structures made is very good.

To the best of the authors’ knowledge, the paper presents a new, unpublished method of manufacturing electrodes (resistors) on silicon, Al₂O₃ and low temperature co-fired ceramic substrates based on the authors developed computer program.

The purpose of this paper is to verify the principal conclusions, done during the implementation of FP7 ASPIS project objectives in fundamental research of ENIG‐related failures by investigating real problematic PCB samples of different suppliers.

SEM, EDS and XPS techniques were applied for morphology and composition studies of ENIG coatings of three PCB samples (A, B and C), while electrochemical measurements were used to determine the porosity of EN and IG layers.

The surface morphology analysis of the un‐soldered pads of PCB A disclosed the fact that the surface of substrate was not pre‐treated in a proper manner before EN deposition, which generated structural defects such as cracks and opening pores in the EN layer, which in turn could produce the voids in the solder layer during the soldering process. The results of PCB B analysis confirmed the authors' observation that Au layers deposited on EN substrate from IG solution contaminated with Cu ions are highly porous and loosely adhering to EN coating, which, in addition, undergoes serious corrosion damages and may be the principal reason for the black pad defect occurrence. High porosity of IG deposit and the presence of the intermediate layer between Au and Ni‐P, which was enriched in Cu and O, were the main reasons for the black pad issue in the case of PCB C.

The gained knowledge on the mechanism of ENIG‐related failures, which cause reliability problems in PCB manufacture, makes it possible to elaborate potential non‐destructive techniques for detecting ENIG problems.