Effect of Plating Layers on the Bonding Strength of p-Type Bi–Te Thermoelectric Elements

In thermoelectric modules, multiple n-type and p-type thermoelectric elements are electrically connected in series on a Cu electrode that is bonded to a ceramic substrate. Defects in the bond between the thermoelectric elements and the Cu electrode could impact the performance of the entire thermoelectric module. This study investigated the effect of plating layers on the bonding strength of p-type Bi–Te thermoelectric elements. Ni and Pd electroplating was applied to Bi–Te thermoelectric elements; further, electroless Ni–P immersion gold (ENIG) plating was applied to Cu electrodes bonded to ceramic substrates. Forming a Pd/Ni electroplating layer on the surface of thermoelectric elements and an ENIG plating layer on the surface of the Cu electrode improved the bonding strength by approximately 3.5 times. When the Pd/Ni and ENIG plating layers were formed on Bi–Te elements and Cu substrates, respectively, the solderability greatly increased; as the solderability increased, the thickness of the diffusion layer formed with the solder layer increased. The improved bonding strength of the Pd/Ni plated thermoelectric element bonded on the ENIG plated substrate is attributed to the enhanced solderability due to the rapid inter-diffusion of Pd and Au into the solder layer and the formation of a stable and non-defected solder reaction interface layer.

Effectiveness of Electrical and Optical Detection at Pixel Circuit on Thin-Film Transistors

The paper presents a typology of electrical open and short defects on thin-film transistors (TFT) using an electrical tester and automatic optical inspection (AOI). The experiment takes the glass 8.5th generation to detect the electrical characteristics engaged with time delay and integration (TDI) charged-coupled-devices (CCDs), a fast line-scan, and a review CCD with five sets of magnification lenses for further inspection. An automatic data acquisition program (ADAP) controls the open/short (O/S) sensor, TDI-CCD, and motor device for machine vision and statistics of substrate defects simultaneously. Furthermore, the quartz mask installed on AOI verified its optical resolution; a TDI-CCD can grab an image of a moving object during transfers of the charge in synchronous scanning with the object that is significant.

Applying Selective Laser Melting to Join Al and Fe: An Investigation of Dissimilar Materials

Combining aluminum and steel is a major goal of automobile manufacturers and other industries because the hybrid material reduces the weight of components. However, differences in chemical properties, thermal expansion, and physical characteristics of aluminum and steel are barriers to achieving this goal. In this article, selective laser melting (SLM), which is widely used in industrial fields, was applied to join dissimilar materials by printing aluminum on a steel substrate. Defects of joining during the SLM process, characteristics of the intermetallic reaction layer, and the effects of the process parameters were investigated. The analysis indicates that flake behavior could affect the quality of joining. The phases of the intermetallic layer found in this study were in agreement with other research, but the morphology of the layer was much different. A formula to estimate the join quality in terms of density energy is proposed. The results indicate that the SLM process is a promising method to manufacture a hybrid material.

Synergetic effects of strain engineering and substrate defects on generating highly efficient single-atom catalysts for CO oxidation

Developing highly efficient single-atom catalysts (SACs) containing isolated metal atom monomers dispersed on appropriate substrates has surged to the forefront of heterogeneous catalysis in recent years.

Effect of Build Orientation on the Microstructure and Mechanical Properties of Selective Laser-Melted Ti-6Al-4V Alloy

One of the challenges of additive manufacturing (AM) technology is the inability to generate repeatable microstructure and mechanical properties in different orientations. In this work, the effect of build orientation on the microstructure and mechanical properties of Ti–6Al–4V specimens manufactured by selective laser melting (SLM) was studied. The samples built in the Z orientation showed weaker tensile strength compared to the samples built in X, and Y orientations. Samples built in X and Y orientations exhibited brittle fracture features in areas close to the substrate and ductile fracture features in the area farther from the substrate. Defects including pores, cracks, and unmelted/partially-melted powder particles contributed to lower tensile and fracture toughness properties in different orientations.