Reliability modeling and assessment of solder joints of electronic assemblies under mixed exposure to mechanical loads

Purpose In this paper, a lifetime estimation model for the solder joint is proposed which is capable of considering both severe and running mechanical shocks which is the real case in electric converters in the automotive and aerospace applications. This paper aims to asses the reliability of the solder joint under mixed exposure of mechanical loads. Design/methodology/approach Mechanical failure process may put at risk the perfect performance of any kinds of electronic systems regardless of the applications they are prepared for. Observation of solder joint health in an electronic assembly under simultaneous exposure of severe and running shocks is an open problem. Three commonly used soldering compositions are considered while the electronic assembly is exposed to three well-known driving cycles. Findings The results show that the best performance is achieved using SAC405 soldering alloy in comparison with Sn63Pb37 and SAC387 solder alloy. Consideration of mixed exposure to the mechanical loads leads to much more accurate lifetime estimation of the solder joint in the electronic assemblies. Originality/value The originality of the paper is confirmed.

Thiol-disulfide homeostasis and ischemia-modified albumin levels as indicators of oxidative stress in welders’ lung disease

Welders’ lung disease refers to mixed exposure to different kinds of metals and chemicals from welding fumes, which affect all parts of the respiratory tract including airways and parenchyma together. This study aimed to investigate the oxidative status in patients with welders’ lung (PWL) by means of thiol-disulfide homeostasis and ischemia-modified albumin (IMA) levels. The male welder workers diagnosed with welders’ lung disease and healthy individuals were recruited in the study. Plasma levels of disulfide, disulfide/native thiol ratio, disulfide/total thiol ratio, IMA, and catalase (CAT) were determined. Pulmonary function test parameters of both groups were compared. The thiol-disulfide homeostasis parameters of PWL and control group were as follows: disulfide (20.5 ± 6.3 vs. 16.2 ± 3.9 μmol L−1, p < 0.001), disulfide/native thiol (4.36 (1.59) vs. 4.0 (1.64), p = 0.024), and disulfide/total thiol (4.01 (1.34) vs. 3.71 (1.41), p = 0.024). IMA levels in PWL were significantly higher than the control group (1.37 (0.27) mg dL−1 vs. 0.49 (0.61) mg dL−1, p < 0.001), whereas CAT activities were significantly higher in the control group (106.6 (54.5) kU L−1 vs. 78.3 (67.8) kU L−1, p = 0.003). The findings of the present study revealed that oxidative stress plays a key role in the pathogenesis of welders’ lung disease. Plasma thiol-disulfide homeostasis and IMA levels might be indicators of oxidative stress in PWL.

Reduction in semen quality after mixed exposure to bisphenol A and isobutylparaben in utero and during lactation periods

This study was performed to determine the effect of low-level exposure to a mixture of bisphenol A (BPA) and isobutylparaben (IBP) on male reproduction. Corn oil, BPA (0.05 mg/kg/day), IBP (2.5 mg/kg/day), and a BPA/IBP mixture (BPA 0.05 mg/kg/day and IBP 2.5 mg/kg/day) were administered once daily by oral gavage to female rats for 5 weeks from gestation day 6 to lactation day 21. Male pups were killed at postnatal day 70 and examined for developmental characteristics, body weight, testis and epididymis weight, steroid hormones, epididymal sperm count and motility, and histological changes in testis and epididymis. The BPA/IBP mixture produced a significant downregulation of epididymal sperm count and motility. BPA or IBP alone also reduced epididymal sperm count and motility compared to control. These results indicate that exposure to low-level BPA/IBP mixture, which showed no notable physiological response in early life stages, can decrease semen quality in adulthood.