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The purpose of this paper is to study the effect of intermetallic compound (IMC) layer thickness on the shear strength of surface-mount component 1206 chip resistor solder joints.

To evaluate the shear strength and IMC thickness of the 1206 chip resistor solder joints, the test vehicles were conventionally reflowed for 480 seconds at a peak temperature of 240°C at different isothermal ageing times of 100, 200 and 300 hours. A cross-sectional study was conducted on the reflowed and aged 1206 chip resistor solder joints. The shear strength of the solder joints aged at 100, 200 and 300 hours was measured using a shear tester (Dage-4000PXY bond tester).

It was found that the growth of IMC layer thickness increases as the ageing time increases at a constant temperature of 175°C, which resulted in a reduction of solder joint strength due to its brittle nature. It was also found that the shear strength of the reflowed 1206 chip resistor solder joint was higher than the aged joints. Moreover, it was revealed that the shear strength of the 1206 resistor solder joints aged at 100, 200 and 300 hours was influenced by the ageing reaction times. The results also indicate that an increase in ageing time and temperature does not have much influence on the formation and growth of Kirkendall voids.

A proper correlation between shear strength and fracture mode is required.

The IMC thickness can be used to predict the shear strength of the component/printed circuit board pad solder joint.

The shear strength of the 1206 chip resistor solder joint is a function of ageing time and temperature (°C). Therefore, it is vital to consider the shear strength of the surface-mount chip component in high-temperature electronics.

Labour market constraints constitute prominent obstacles to firm development and economic growth of countries located in the Middle East and North Africa (MENA) region. The purpose of this paper is to examine the implications of firm characteristics, national locations, and sectoral associations for the perceptions of firms concerning two basic labour market constraints: labour regulations and labour skill shortages.

The empirical analysis is carried out using firm-level data set sourced from the World Bank’s Enterprise Surveys database. A bivariate probit estimator is used to account for potential correlations between the errors in the two labour market constraints’ equations. The authors implement overall estimations and comparative cross-country and cross-sector analyses, and use alternative estimation models.

The empirical results reveal some important implications of firm characteristics (e.g. firm size, labour compositions) for firm perceptions of labour regulations and labour skill shortages. They also delineate important cross-country and cross-sector variations. The authors also find significant heterogeneity in the factors’ implications for the perceptions of firms belonging to different sectors and located in different MENA countries.

Reforms in labour regulations and investment in human capital are important governmental policy interventions for promoting firm development and economic growth in the MENA region. This paper contributes to the empirical literature by analysing the factors influencing the perceptions of firms located in the MENA region concerning labour regulations and labour skill shortages. It provides policy-makers with information needed in the design of labour policies that attenuate the impacts of labour market constraints and enhance the performance of firms and the long-run economic growth.

The purpose of this work is to undertake a comparison of accelerated test regimes for assessing the reliability of solder joints, in particular those made using lead‐free solders.

Identical samples of 1206, 0805 and 0603 resistors were subjected to six different cycling regimes to investigate the effect of thermal excursions, ramp rates and temperature dwells.

The most damage to joints was found to be caused by thermal cycling between −55 and 125°C, with a 10°C/min ramp rate and 5 min dwells. Large thermal excursions were shown to give faster results without compromising the failure mode.

Similar degrees of damage in the lead‐free solder joints were experienced from thermal shock regimes with ramp rates in excess of 50°C/min. However, these regimes, although faster to undertake, appeared to cause different crack propagation modes than observed with the thermal cycling regimes. However, these differences may be small and thermal shock testing may still be used to differentiate between, or enable ranking of, the effects of changes to materials or processes on the reliability of the solder joints. Hence, it is envisaged that if a wide range of conditions are to be tested a first sift can be completed using thermal shock, with the final work using typical thermal cycling conditions.

The difference between the SAC (95.5Sn3.8Ag0.7Cu) and SnAg (96.5Sn3.5Ag) solder alloy results across all types of cycles showed very little difference in the rates of joint degradation.

This paper compares relative reliability (remaining shear strength) of three chip components soldered with two lead‐free alloys based on various thermal cycling conditions.

Enclosed print heads have recently been developed as an improvement on the traditional squeegee methods for solder paste printing. They offer the opportunity of widening the printing process window and reducing process waste. Consequently, this work was undertaken to evaluate some aspects of enclosed print head printing, and it has been shown to be a robust process. A number of performance factors were established: with increased humidity the paste degradation was limited due to its sealed paste reservoir; the system also permitted successful intermittent printing over a 5 day period; printing is much more tolerant to distorted substrates than some squeegee blades, and hence improves printing on non‐planar surfaces; significant reduction in paste wastage occurs, since paste ageing is reduced.

The surface mount technology (SMT) assembly process for 0.4 mm pitch chip scale package (CSP) components was studied in this work. For the screen printing process, the printing performance of different solder pastes, aperture shapes and sizes was investigated. Square apertures and a fine particle size in the solder paste provided a better paste release. Besides optimising the printing process capability and minimizing the printing defects such as bridging and missing paste, the total volume of solder consisting of the paste and the solder ball has to be considered in order to maximize the final process yield. For the pick & place process, the accuracy required for the placement equipment was determined by studying the self‐alignment of the lead‐free CSPs (with Sn/4.0Ag/0.5Cu balls) during the reflow process using lead‐free Sn/3.9Ag/0.6Cu paste. The components were intentionally misplaced up to ∼50percent off‐pad. After reflow, x‐ray inspection showed that the components had aligned to the pad. By considering the stack‐up of the printed circuit board pad location and size tolerances, the solder paste printing tolerances and the placement tolerances, the required alignment accuracy for the pick & place equipment was established to meet the total process capability requirement.

This study aims to synthesize new cyclodiphosph(V)azane derivatives, 2,2,4,4-tetrachloro-1,3-di-[o-nitriyl]-2,4-di-[N-(pyrimidin-2-yl)benzenesulfonamide]-1,3,2,4- diazadiphosphetidine(H2L) ligand and their Fe(III) and Ag(I) metal complexes as insecticides for protective coatings.

The substitutes of cyclodiphosph(V)azane sulfonomide and their Fe(III), Ag(I) metal complexes were prepared and confirmed by a combination of elemental analyses, mass spectra, conductivity measurement-vis, FTIR, 1H,13C-NMR TGA, XRD and Docking investigation of the ligand and some complexes to verify their drug ability. The prepared compounds have been incorporated with a polyurethane (PU) coating formula. Gloss, scratch resistance, flexibility and adhesion are some of the coating attributes investigated; mechanical capabilities include impact resistance and shore hardness and physicochemical properties such as chemical resistance of coated PU samples are also investigated.

The results of the experiments revealed that all PU coatings based on the prepared compounds had good scratch resistance which varied from >1.8 to >2.2 kg. Gloss value varied from 85 to 95 and impact resistance from 1.4 to 2.0 (J), whereas the authors noticed that there was no effect of the prepared compounds in the flexibility and adhesion test. These PU coatings have excellent chemical resistance except the alkali resistance. Insecticide activities of the prepared compounds are promising for resistance to these insects. It was noticed that, metal complex > incorporated PU with Fe (III) metal complex > incorporated PU with ligand.

Insecticide paints based on cyclodiphosph(V)azane sulfonamide and their Fe(III), Ag(I) metal complexes as insecticide agents are novel.

The purpose of this paper is to investigate the inhibitive effect of the phosphite NaCo(H₂PO₃)₃•H₂O (PhCo) for the corrosion of mild steel in HCl solutions. The study is another trial to find a mineral inhibitor for mild steel corrosion.

The inhibitory effect has been evaluated by gravimetric and polarisation techniques at various temperatures. The type of adsorption inhibition and adsorption and kinetic data are determined.

Results show that PhCo inhibits the corrosion of steel in acidic solution. The inhibition efficiency at 308 K increases with the inhibitor concentration to reach 96 per cent for 10⁻⁴ M, and then decreases at higher temperatures. Kinetic parameters such as E_a, ΔH_a^∘ and ΔS_a^∘ were calculated. The adsorption of inhibitor obeys the Langmuir isotherm model. Thermodynamic parameters of adsorption including ΔG_ad, ΔH_ad, ΔS_ad, and K_eq(ad) were calculated in the presence of inhibitor.

Electrochemical studies (polarization method) show the partial action of inhibitor on anodic and cathodic reactions of the corrosion inhibition.

The efficiency of the tested phosphite increases with its concentration to reach 96 per cent. It can be used in chemical cleaning and pickling processes at moderate temperature.

This paper reveals the possible application of phosphites as environmentally valid inhibitors for corrosion under the specified conditions.

To investigate how jamming of particles in a solder paste varies as a function of the gap through which the particles flow, and to correlate this with skipping defects during the printing process.

Solder pastes with particle sizes of types 2, 3, 4 and 5 were sheared between the parallel plates of a rheometer. Jamming events that cause the solder particles to be forced against each other were detected by monitoring the electrical current flowing between the plates under a bias of 1.0 V or less. Solder paste printing trials were conducted with the same pastes, and solder paste skipping monitored.

Jamming was detected when the ratio of plate gap to largest particle diameter is reduced to a value between 3.8 and 5.0. Decreasing the gap further results in increased jamming. A strong correlation between levels of skipping and jamming was found.

More extensive printing trials are required before rheometric jamming detection can be used to predict printing performance.

The common rule of thumb used in solder paste printing that the aperture width should be no smaller than 4‐5 particle diameters is justified.

This paper presents a new technique for detecting jamming events which are too brief to be detected using normal rheometric techniques, but which have long been thought to be responsible for stochastic skipping defects during printing. Evidence supporting the link between jamming and this type of defect is presented.