Atomic Layers from Solution: Growth of flat thin films is often plagued by the formation of mounds and pyramids. To avoid this problem, atomic-layer deposition (ALD) can be used whereby alternating self-termination reactions stop the layer growth. Electrochemical approaches to ALD use surface alloys to slow film growth, but often lead to film contamination. Yihua Liu et al. (p. 1327 ; see the Perspective by Switzer ) show that for platinum films, controlling surface potential can lead to adsorbed hydrogen on the surface, which can terminate film growth at one layer, leaving platinum species in solution available for further reduction. Rapid changes in applied potential can oxidize the hydrogen, which allows efficient contamination-free growth of an additional atomic layer.

The work exploring the stoichiometry of Pt deposition via surface-limited redox replacement of the underpotentially deposited (UPD) Cu monolayer on Au(111) is presented. The Cu UPD monolayer is formed from solution, whereas the Pt deposition via surface-limited redox replacement reaction is carried out in solution at open-circuit potential. Our results indicate that the Pt submonolayers have two-dimensional morphology and linear dependence of their coverage on the amount (coverage) of the replaced Cu UPD monolayers. Our analysis shows that the oxidation state of Cu during redox replacement reaction is , suggesting that four Cu UPD adatoms are replaced by each deposited Pt adatom. This work stresses the general importance of the anions, determining the stoichiometry of metal deposition reaction via surface-limited redox replacement of the UPD monolayers.

Surface Mount Technology (SMT) is a procedure for mounting electronic components to the surface of the printed circuit boards (PCB). Although the SMT procedure is more reliable than the conventional through-hole mounting, many errors may occur in SMT lines. In this paper, we surveyed methods presented for the optical inspection of solder joints on PCBs. The methods are grouped by problem-solving approach: reference-based, machine learning/computer vision, deep learning, and 3D reconstruction. We compare and discuss these approaches according to their advantages and disadvantages, with a focus on the more recent deep learning and 3D reconstruction techniques, and list the public datasets for solder joints inspection. Since defective samples rarely occur in the SMT manufacturing lines, public datasets have few defective samples that are essential for the inspection task. To fill this gap, we publish a public dataset with both normal and different types of SMT errors. Our dataset can be used as a benchmark to compare different algorithms. The dataset is available at https://github.com/furkanulger/solder-joint-dataset.

This study presents the design and fabrication of a flexible tactile sensor printed on a cellulose paper substrate using a carbon black (CB) – filled polyvinyl alcohol (PVA) polymer matrix as ink material. In the design, electrodes are obtained by screen printing of CB/PVA composite on dielectric cellulose paper. The screen-printing method is preferred for fabrication because of its simplicity and low manufacturing cost. The tactile sensor is formed by overlapping two ink-printed sheets. Electrical properties are investigated under compressive and tensile strains. The results indicate that the tactile sensor configuration and materials can be used for piezoresistive, capacitive, and also impedance sensors. The same tactile sensor structure is also examined using a commercial carbon-based ink for performance comparison. The comparative study indicates that CB/PVA ink screen-printed on paper demonstrates superior sensitivity for capacitive sensing with low hysteresis, as well as low response and recovery times. The piezoresistive-sensing properties of CB/PVA on cellulose paper show a gauge factor (GF) of 10.68, which is also very promising when conventional metal strain gauges are considered. CB/PVA screen-printed on cellulose paper features impedance-sensing properties and is also sensitive to the measurement frequency. Therefore, the response type of the sensor can be altered with the frequency.