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This paper aims to describe and document the application of commonly utilized solder joint failure analysis techniques to lead‐free solder joints.

Traditional failure analysis techniques, including visual inspection, X‐ray radiography, mechanical strength testing, dye and pry, metallography, microscopy and photomicrography, are reviewed. These techniques are demonstrated as applied to lead‐free and tin lead solder joints. Common failure modes observed in lead‐free and tin lead solder joints are described and compared.

It is shown that the traditional failure analysis techniques previously utilized for tin lead solder joints are widely applicable to the analysis of lead‐free solder joints. The changes required to effectively apply these techniques to the analysis of lead‐free solder joints are described.

This paper will be instrumental to the process, quality, reliability and failure analysis engineering disciplines in furthering understanding of the application of failure analysis techniques of both tin lead and lead‐free solder joints.

The purpose of this paper is to compare the performance of X‐ray fluorescence (XRF) instruments with different detector systems (proportional counter, positive intrinsic negative and Si drift detectors) for measuring thin Au and Pd coatings on printed circuit boards and to investigate different ways of background treatment. It also aims to provide and certify suitable reference materials which are similar to samples used in production.

XRF measurements were performed with different instruments and detector types. The quantification of the reference materials is based on XRF, gravimetric analysis and Rutherford backscattering (RBS).

The well‐established X‐ray instrumentation for coating thickness measurement, with proportional counter detectors, are not very suitable for measuring thin ( < approx. 100 nm) coatings of gold and palladium due to the poor energy resolution of the proportional counter‐tubes. Systems with semiconductor detectors achieve results that are more reliable with a significantly higher accuracy. A correct background treatment is especially important for very thin coatings. The composition of the base material has to be taken into account by the software evaluation algorithm for each measurement. A global base subtraction performed prior to the measurement can achieve better repeatability, but can also lead to incorrect absolute values.

If small measuring spots (e.g. 150 μm) have to be realized with semiconductor detector systems, special X‐ray optics (polycapillaries) have to be used to obtain an intensity comparable to that offered by proportional counter devices. This will be the subject of a further publication.

The paper provides an overall review and results for different types of instruments (detectors) and compares different background treatments. Suitable reference materials have been developed for precise and traceable measurements. Their quantification is based on gravimetric analysis and RBS. The standard‐free energy dispersive X‐ray fluorescence (ED‐X‐ray fluorescence analysis (XRFA)) was used for interpolation of the gravimetric data for thin coatings. For the region below 100 nm, measurement uncertainties of less than 1 nm can be achieved.

In the previous two articles the emphasis was on wet and electrochemical techniques, with particular reference to the potentiostat. The physical examination of corrosion products is of equal importance, especially, for example, in the study of oxidation by dry gases at elevated temperatures where electrochemical studies are not normally feasible. In this article the application of physical techniques to corrosion studies will be discussed.

The X‐ray diffraction patterns of epoxy resins: four samples with different epoxide equivalents and coal‐tar blended epoxy resins: three samples with different epoxide equivalents were recorded using CuKa X‐ray radiation. These X‐ray diffraction patterns were indicating the amorphous nature of the resins. Their intensity curves were subjected to Fourier Analysis for the first time in order to get more information about the difference between epoxy and coal‐tar blended epoxy resins in terms of their internal structure such as particle size, percentage crystallanity and electron density fluctuations. Also, the effect of different epoxide equivalent on these physical parameters was interpreted successfully in epoxy as well as coal‐tar blended epoxy resins.

The purpose of this study was to fabricate carbon nanotubes (CNT)-reinforced chromium oxide coatings and investigate mechanical and microstructural properties of these newly developed coatings on the boiler tube steel.

1 and 4 Wt.% CNT-reinforced Cr₂O₃ composite coatings were prepared and successfully deposited on ASTM-SA213-T22 (T22) boiler tube steel substrates using high-velocity oxy fuel (HVOF) thermal spraying method. Microhardness, porosity, metallography, X-ray diffraction (XRD), scanning electron microscopy (SEM)/energy-dispersive X-ray spectroscopy, cross-sectional elemental analysis and X-ray mapping analysis have been used to examine the coated specimens.

The porosity of the CNT-Cr₂O₃ composite coatings was found to be decreasing with the increases in CNT content, and hardness has been found to be increasing with increase in percentage of CNT in the composite coatings. The CNT were able to increase hardness by approximately 17 per cent. It was found that the CNT were uniformly distributed throughout Cr₂O₃ matrix. The CNT were found to be chemically inert during the spraying process.

It must be mentioned here that studies related to fabrication of HVOF sprayed CNT reinforced Cr₂O₃ composite coatings on T22 boiler tube steel are not available in the literature. Hence, present investigation can provide valuable information related to fabrication and properties of CNT reinforced coatings on boiler steel.

To develop a method for the preparation of micaceous zinc ferrite (MZF), anticorrosive pigment having desirable chemical and physical properties.

MZF pigment was prepared after firing the oxidised solid molten salts without washing. The MZF pigment obtained was characterised using X‐ray diffraction analysis, crystal size analysis, scanning electron microscope and energy dispersive X‐ray analysis. The pigment obtained was also evaluated chemically with respect to moisture content, content of water‐soluble salts, hydrogen ion concentration (pH) and weight loss; and physically with respect to particle shape, colour, specific gravity and oil absorption. Commercially available micaceous iron oxide and zinc ferrite pigments were also characterised in comparison.

A spinel, MZF pigment was prepared using relevant oxidised solid molten salts. The preparation produced a lamellar structure with a basic nature giving not only barrier protection but also chemical passivation of the substrate.

The anticorrosive properties of the pigments obtained could be evaluated using more conventional methods such as salt‐spray test.

The pigment prepared could be used as a highly efficient pigment for anticorrosion coating for steel.

The method for the preparation of MZF pigment was novel. The pigment obtained could be used in various resin systems to produce anticorrosive paints for steel protection.

The esterified maleic and fumaric resins have been studied by X‐ray diffraction. Their diffraction halos have been subjected to a Fourier analysis for the first time and the physical parameters like particle size, percentage crystallanity and electrondensity fluctuations along the length of the polymer molecule have been evaluate out by standard methods. The results indicate that the two resins are isomeric in nature. This conclusion is further supported by a measurement of the variation in ultrasonic velocity with concentration in xylene solutions of these resins.

This paper aims to investigate voiding phenomena in solder joints under thermal pads of light-emitting diodes (LEDs) assembled in mass production environment by reflow soldering by using seven low-voiding lead-free solder pastes.

The solder pastes investigated are of SAC305 type, Innolot type or they are especially formulated by the manufacturers on the base of (SnAgCu) alloys with addition of some alloying elements such as Bi, In, Sb and Ti to provide low-void contents. The SnPb solder paste – OM5100 – was used as a benchmark. The solder paste coverage of LED solder pads was chosen as a measure of void contents in solder joints because of common usage of this parameter in industry practice.

It was found that the highest coverage and, related to it, the least void contents are in solder joints formed with the pastes LMPA-Q and REL61, which are characterized by the coverage of mean value 93.13% [standard deviation (SD) = 2.72%] and 92.93% (SD = 2.77%), respectively. The void diameters reach the mean value equal to 0.061 mm (SD = 0.044 mm) for LMPA-Q and 0.074 mm (SD = 0.052 mm) for REL61. The results are presented in the form of histograms, plot boxes and X-ray images. Some selected solder joints were observed with 3D computer tomography.

The statistical analyses are carried out on the basis of 2D X-ray images with using Origin software. They enable to compare features of various solder pastes recommended by manufacturers as low voiding. The results might be useful for solder paste manufacturers or electronic manufacturing services.

Hot corrosion is the major degradation mechanism of failure of boiler and gas turbine components. The present work aims to investigate the hot corrosion resistance of detonation gun sprayed (D-gun) Cr₂O₃-75 per cent Al₂O₃ ceramic coating on ASTM-SA210-A1 boiler steel.

The coating exhibits nearly uniform, adherent and dense microstructure with porosity less than 0.8 per cent. Thermogravimetry technique is used to study the high temperature hot corrosion behavior of bare and coated boiler steel in molten salt environment (Na₂SO₄-60 per cent V₂O₅) at high temperature 900°C for 50 cycles. The corrosion products are analyzed by using X-ray diffraction, scanning electron microscopy (SEM) and field emission scanning electron microscope/energy-dispersive analysis (EDAX) to reveal their microstructural and compositional features for elucidating the corrosion mechanisms.

During investigations, it was found that the Cr₂O₃-75 per cent Al₂O₃ coating on Grade A-1 boiler steel is found to be very effective in decreasing the corrosion rate in the molten salt environment at 900°C. The coating has shown lesser weight gains along with better adhesiveness of the oxide scales with the substrate till the end of the experiment. Thus, coatings serve as an effective diffusion barrier to preclude the diffusion of oxygen from the environment into the substrate boiler steel.

Therefore, it is concluded that the better hot corrosion resistance of the coating is due to the formation of desirable microstructural features such as very low porosity, uniform fine grains and the flat splat structures in the coating; as compared to the bare substrate under cyclic conditions.

This research is useful for coal-fired boilers and other power plant boilers.

This research is useful for power generation plants.

There is no reported literature on hot corrosion behavior of Cr₂O₃-75 per cent Al₂O₃ coating deposited on the selected substrates by D-gun spray technique. The present work has been focused to study the influence of the Cr₂O₃-75 per cent Al₂O₃ coating developed with D-gun spraying technique on high temperature corrosion behavior of ASTM-SA210-A-1 boiler steel in an aggressive environment of Na₂SO₄-60 per cent V₂O₅ molten salt at 900°C under cyclic conditions.

To prepare of fine particle size magnesium ferrite pigments by sol‐gel method.

Different magnesium ferrite pigments with stoichiometric ratios were prepared by sol‐gel and dispersion methods. The characterisation of magnesium ferrite pigments were based on X‐ray diffraction, transmission electron microscope, particle size distribution, thermal and magnetometric analyses.

The type of polymer and the starting inorganic materials (oxides or salts) have a significant effect on the properties of the magnesium ferrite pigments prepared.

The magnesium ferrite pigments, prepared and used in the work reported here were synthesised from magnesium and iron oxides, oxalates and chlorides. Urea formaldehyde resin and acrylic polymer were used as the dispersing media. Various other materials, e.g. carboxymethyl cellulose, ethoxy methyl cellulose, polyvinylalcohol and 2‐hydroxyethyl methacrylate and polyacrylamide can also be used to achieve similar effect.

The sol‐gel method provided a fine particle size and different particle shapes. Therefore, the method of preparation could be used to produce fibres, films and monoliths.

The magnesium ferrite pigments prepared could be use in numerous paints for steel protection.