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This study examines solvent extract conductivity (SEC) testing, e.g., Ionograph or Omega Meter testing, which measures ionic cleanliness of printed wiring boards (PWBs). SEC has been a quality control (QC) monitor to assure product electrical reliability. Typical SEC measurements occur after wave soldered products have been solvent‐cleaned. This study concerns SEC testing on new wave soldering processes that involve no solvent cleaning, i.e., inert gas soldering with ‘no clean’ fluxes. Results show ionic residues from ‘no clean’ fluxes may have other characteristics that make QC testing for ionic cleanliness inappropriate. However, SEC may be appropriate as a process control monitor after soldering with these fluxes. An Ionograph measured SEC response for the following chemicals: NaCl, NaF, NaBr, KCl, MgCl2, CaCl2, HCl, succinic acid, malic acid, glutaric acid, adipic acid and ethylene glycol. The list includes inorganic salts, strong electrolytes, which may arise from manufacturing or PWB materials. The list also includes weak organic acids (WOAs) common to ‘no clean’ fluxes. One non‐ionic hygroscopic chemical, ethylene glycol, was studied. Ionograph response was measured via (i) direct injection of aqueous solutions and (ii) immersion of PWBs with individual chemicals as surface deposits. All ionisable compounds, including all WOAs, produced substantial SEC response. Surface conductivity was measured at 35°C/90% relative humidity (RH) with controlled amounts of the above chemicals deposited on clean PWB test circuits. Surface loadings corresponded to the molar‐ionic equivalent of 2.0 ?g/cm2 NaCl. In addition, NaCl, adipic acid and polyethylene glycol (PEG 400) were examined as a function of concentration. Several ionisable chemicals including all WOAs produced no measurable effect, i.e., surface conductivities were indistinguishable on clean and deposited specimens. Surface conductivity increased for ionic contaminants with critical RH below ∼80% and for the non‐ionic hygroscopic glycol. SEC measurements and surface conductivities were compared. The latter is more directly related to electrical reliability. Although all ionic compounds including the WOAs showed a SEC response, not all enhanced surface conductivity. Achievement of critical RH appears to be the important factor. Adipic acid required the presence of hygroscopic glycol to enhance surface conductivity. Therefore, SEC can be a misleading QC test for electrical reliability when WOA flux residues are present.

The technique of Optically Stimulated Electron Emission (OSEE) is considered as a method of inspecting printed circuit based electronics assemblies for flux residue immediately following production soldering. The technique has been used for several years by NASA and its contractors in the refurbishment of solid rocket motors for the Space Shuttle. The application to copper substrates and soldered copper substrates has shown sensitivity to small amounts of residues of some solder fluxes. The technique was extended for inspection of insulating substrates used in printed wiring board (PWB) construction by altering the measurement procedure to include charge replacement, thereby attaining measurement reproducibility. The results indicate that OSEE inspection of electronic assemblies for flux residues is feasible. An inspection based on this technology subjects the inspected object only to photons of ultra‐violet light and immersion in an inert gas, such as argon. It is potentially rapid enough to provide 100% inspection of boards processed on a production line, and it has potential spatial resolution of less than 1 micron.

The purpose of this study is to show that the humidity levels for surface insulation resistance (SIR)-related failures are dependent on the type of activators used in no-clean flux systems and to demonstrate the possibility of simulating the effects of humidity and contamination on printed circuit board components and sensitive parts if typical SIR data connected to a particular climatic condition are available. This is shown on representative components and typical circuits.

A range of SIR values obtained on SIR patterns with 1,476 squares was used as input data for the circuit analysis. The SIR data were compared to the surface resistance values observable on a real device printed circuit board assembly. SIR issues at the component and circuit levels were analysed on the basis of parasitic circuit effects owing to the formation of a water layer as an electrical conduction medium.

This paper provides a summary of the effects of contamination with various weak organic acids representing the active components in no-clean solder flux residue, and demonstrates the effect of humidity and contamination on the possible malfunctions and errors in electronic circuits. The effect of contamination and humidity is expressed as drift from the nominal resistance values of the resistors, self-discharge of the capacitors and the errors in the circuits due to parasitic leakage currents (reduction of SIR).

The methodology of the analysis of the circuits using a range of empirical leakage resistance values combined with the knowledge of the humidity and contamination profile of the electronics can be used for the robust design of a device, which is also important for electronic products relying on low current consumption for long battery lifetime.

Examples provide a basic link between the combined effect of humidity and contamination and the performance of electronic circuits. The methodology shown provides the possibility of addressing the climatic reliability of an electronic device at the early stage of device design by using typical SIR data representing the possible climate exposure.

Over the last several decades, businesses have faced mounting pressures from diverse stakeholders to alter their corporate operations to become more socially and environmentally responsible. In turn, many firms appear to have responded by implementing more sustainable practices — measuring, documenting, and publishing annual CSR or sustainability reports to showcase how they are addressing important issues in this area, including: resource stewardship, waste management, greenhouse gas emission reductions, fair and safe labor practices, amongst other stakeholder concerns. And yet, research in this domain has not yet systematically examined whether businesses have, on the whole, changed their practices in tandem with the important changes in its institutional context over time. Have corporate CSR initiatives, in fact, been growing over the last 25 years or has the increased attention to CSR actually been much ado about nothing? In this chapter, we review the empirical literature on CSR to uncover that common measures of CSR such as the KLD do not support the concept that CSR practices have increased substantively over the last 25 years. We supplement this historical review by modeling the growth curves of CSR implementation in practice and find that the pace of positive change has indeed been glacial. More alarmingly, we also look at corporate social irresponsibility (CSiR) and find that, contrary to expectations, businesses have become more, not less, irresponsible during this same time period. Implications of these findings for theory are presented as are suggestions for future research in this domain.

This paper aims to investigate the effect of no-clean flux chemistry with various weak organic acids (WOAs) as activators on the corrosion reliability of electronics with emphasis on the hygroscopic nature of the residue.

The hygroscopicity of flux residue was studied by quartz crystal microbalance, while corrosive effects were studied by leakage current and impedance measurements on standard test boards. The measurements were performed as a function of relative humidity (RH) in the range from 60 to ∼99 per cent at 25°C. The corrosiveness of solder flux systems was visualized by the ex situ analysis using a gel with tin ion indicator.

The results showed that the solder flux residues are characterized by different threshold RH, above which a sudden increase in direct current leakage by 2–4 orders of magnitude and a significant reduction in surface resistance in the impedance measurements were observed.

The findings are attributed to the deliquescence RH of the WOA(s) in the flux and chemistry of water-layer formation. The results show the importance of WOA type in relation to its solubility and deliquescence RH on the corrosion reliability of printed circuit boards under humid conditions.

The classification of solder flux systems according to IPC J-STD-004 standard does not specify the WOAs in the flux; however, ranking of the flux systems based on the hygroscopic property of activators would be useful information when selecting no-clean flux systems for electronics with applications in humid conditions.

We examine whether discretionary accruals of firms obtaining substantial external financing can be explained by managerial manipulation or managerial overoptimism. Insider trading patterns and press releases around equity and debt financing suggest that managers are more optimistic about their firms around debt financing. Consistent with earlier studies, we find that discretionary current accruals peak when firms obtain equity financing. However, we also find that discretionary accruals peak when firms obtain debt financing. Moreover, discretionary accruals are higher for firms that rely on debt rather than on equity financing. The results are robust to controlling for firm characteristics, excluding small and distressed firms, and using alternative measures of discretionary accruals. These findings support the hypothesis that managerial overoptimism distorts financial statements of firms obtaining external financing.

This article is motivated by the lack of flexibility in Bayesian quantile regression for ordinal models where the error follows an asymmetric Laplace (AL) distribution. The inflexibility arises because the skewness of the distribution is completely specified when a quantile is chosen. To overcome this shortcoming, we derive the cumulative distribution function (and the moment-generating function) of the generalized asymmetric Laplace (GAL) distribution – a generalization of AL distribution that separates the skewness from the quantile parameter – and construct a working likelihood for the ordinal quantile model. The resulting framework is termed flexible Bayesian quantile regression for ordinal (FBQROR) models. However, its estimation is not straightforward. We address estimation issues and propose an efficient Markov chain Monte Carlo (MCMC) procedure based on Gibbs sampling and joint Metropolis–Hastings algorithm. The advantages of the proposed model are demonstrated in multiple simulation studies and implemented to analyze public opinion on homeownership as the best long-term investment in the United States following the Great Recession.

Black boys report experiencing more school-based racial discrimination than any other group (Butler-Barnes et al., 2019). Additionally, Black boys are viewed as older and less innocent than their peers beginning as early as 10 years old (Goff et al., 2014). Black boys are also suspended and expelled at much higher rates than other students (Graves & Wang, 2022). As such, there needs to be an investment in asset-based research designed to understand the factors that can help Black boys cope with these perceptions. Consequently, this chapter will discuss strengths based protective factors that will aid in the promotion of positive outcomes in Black boys.

This bibliography contains references to papers, conference proceedings, theses and books dealing with finite strip, finite prism and finite layer analysis of structures, materially and/or geometrically linear or non‐linear.

This research focuses on the controlling irreversibilities in a radiative, chemically reactive electromagnetohydrodynamics (EMHD) flow of a nanofluid toward a stagnation point. Key considerations include the presence of Ohmic dissipation, linear thermal radiation, second-order chemical reaction with the multiple slips. With these factors, this study aims to provide insights for practical applications where thermal management and energy efficiency are paramount.

Lie group transformation is used to revert the leading partial differential equations into nonlinear ODE form. Hence, the solutions are attained analytically through differential transformation method-Padé and numerically using the Runge–Kutta–Fehlberg method with shooting procedure, to ensure the precise and reliable determination of the solution. This dual approach highlights the robustness and versatility of the methods.

The system’s entropy generation is enhanced by incrementing the magnetic field parameter (M), while the electric field (E) and velocity slip parameters (ξ) control its growth. Mass transportation irreversibility and the Bejan number (Be) are significantly increased by the chemical reaction rate (C_r). In addition, there is a boost in the rate of heat transportation by 3.66% while 0.05⩽ξ⩽0.2; meanwhile for 0.2⩽ξ⩽1.1, the rate of mass transportation gets enhanced by 12.87%.

This paper presents a novel approach to analyzing the entropy optimization in a radiative, chemically reactive EMHD nanofluid flow near a stagnation point. Moreover, this research represents a significant advancement in the application of analytical techniques, complemented by numerical approaches to study boundary layer equations.