In Case You Missed It
Antenna Design
“Flexible Metasurface Loaded Felt Substrate Built Wearable Antenna with Tri-band and High Gain Features for WBAN Applications”
Authors: Dheeray Nagar, Prashant Ranjan and Atanu Chowdhury
Abstract: A low-profile tri-band wearable antenna is presented. The unique features of the proposed antenna design are as follows: 1) With the assistance of dual U-formed printed lines, the proposed wearable antenna works in three different frequency bands; i.e., 2.4GHz, 3.5 GHz and 5.5 GHz; and 2) the single metasurface placed on the backside of the antenna reduces specific absorption rate (SAR) by more than 90% and improves antenna gain (4.55dBi) in all three operating bands. The designed aerial and metasurface have total size of 46.12 × 51.8 × 1.3mm3 and 90 × 90 × 1.3mm3, respectively. Experimental results confirm that the designed aerial operates at 2.4-2.59GHz, 3.15-3.76GHz and 5.1-5.9GHz. Furthermore, the radius of curvature was shown to have no effect on the functioning of the developed antenna, which makes it ideal for on-body measurements. Additional studies on low-cost felt substrate-based antennas for wireless body area network (WBAN) applications may be motivated by this concept. (Journal of Electronic Materials, April 12, 2025, https://doi.org/10.1007/s11664-025-11910-x)
Conductive Materials
“A Novel Modeling and Analysis of Mechanical Properties of Single-Component Thermal Conductive Silica Gel”
Authors: Yuezhen Wang, et al.
Abstract: Single-component thermal conductive silica gel (S-TCSG) is a new type of thermal conductive material for packaging electronic components in high-performance printed circuit boards. Its mechanical properties can lead to excessive deformation of PCBs or even solder joint fracture during screw fastening or falling. The paper details an experimental program developed to study mechanical properties of S-TCSG, such as cushioning property, creep and stress relaxation. The relationship model is established between cushioning coefficient, compression stress and compression strain based on the compression stress-strain test. In addition, the time-varying laws of the compression creep and stress relaxation of S-TCSG were studied experimentally. The elastic modulus, relaxation modulus and creep compliance can be obtained based on the experimental data. A nonlinear finite element model (FEM) of S-TCSG is established. Further, the influence of gel thickness on stress distribution is analyzed in screw tightening. A mathematical model is proposed to characterize the relationship between gel thickness, compressive stress and displacement load. This study is of great practical significance to the rationality of coating thickness of S-TCSG and the performance improvement of PCBs. (Scientific Reports, April 30, 2025, https://doi.org/10.1038/s41598-025-99953-2)
Plating
“Electroplating Behavior of a Phosphorous-Based Cyanide-Free Silver Electrolyte in an Acidic Environment”
Authors: Soojin Lee, et al.
Abstract: This study entailed the development of a novel acidic silver-plating solution using phosphorus-based compounds. A systematic investigation was conducted to optimize the effects of the complexing agents tris(hydroxypropyl)phosphine (THPP), pyrophosphoric acid (PPA) and phosphoric acid (PA) electrolytes on silver reduction and solution stability. Linear sweep voltammetry demonstrated the stabilizing effect of THPP on Ag ions, revealing cathodic polarization of the Ag reduction potential at [Ag+]:[THPP] ratios ranging from 1:1 to 1:5. Notably, the 1:4 ratio exhibited the lowest reduction potential, indicating that the [Ag(THPP)₄]+ complex formed under these conditions was the most stable, a conclusion supported by density functional theory (DFT) calculations. Further, the optimal concentration of the plating solution was determined by analyzing current density variations concerning the concentrations of PPA and PA. The Scharifker–Hills model, energy level analysis using DfT, and cyclic voltammetry elucidated the impact of electrolyte–proton interactions in influencing hydrogen evolution, thereby revealing distinct nucleation mechanisms for Ag reduction in each electrolyte. This study establishes a THPP-based acidic plating solution capable of achieving stable Ag deposition under acidic conditions by optimizing the conditions for complexing agents and electrolytes. These findings suggest the possibility of substituting cyanide-based plating solutions in applications requiring silver plating in acidic environments, potentially enhancing precise plating processes such as pattern plating. (Electrochimica Acta, vol. 523, April 2025, https://doi.org/10.1016/j.electacta.2025.145902)
Semiconductors
“Three-Dimensional Transistors with Two-Dimensional Semiconductors for Future CMOS Scaling”
Authors: Arnab Pal, et al.
Abstract: Atomically thin two-dimensional (2-D) semiconductors – particularly transition metal dichalcogenides – are potential channel materials for post-silicon complementary metal-oxide-semiconductor (CMOS) field-effect transistors. Their application in CMOS technology, however, will require implementation in three-dimensional (3-D) transistors. The authors report a framework for designing scaled 3-D transistors using 2-D semiconductors. The approach is based on non-equilibrium Green’s function quantum transport simulations that incorporate the effects of non-ideal Schottky contacts and inclusive capacitance calculations, with material inputs derived from density functional theory simulations. A comparative performance analysis of different 3-D transistors (2-D and silicon-based) and channel thicknesses is carried out for both low-standby-power and high-performance applications. This suggests that trilayer tungsten disulfide is the most promising material, offering an improvement in energy-delay product of over 55% compared with silicon counterparts, potentially extending CMOS scaling down to a few nanometers. The authors also show that 2-D semiconductors could be uniquely engineered to create 2-D nanoplate field-effect transistors that offer nearly tenfold improvement in integration density and drive current over both 2-D- and silicon-based 3-D field-effect transistors with similar footprints. (Nature Electronics, December 2024; nature.com/articles/s41928-024-01289-8)
