In Case You Missed It

Components

“How a Simple Circuit Could Offer an Alternative to Energy-Intensive GPUs”

Author: Sophia Chen

Abstract: On a table in his lab at the University of Pennsylvania, physicist Sam Dillavou has connected an array of breadboards via a web of brightly colored wires. The setup looks like a DIY home electronics project – and not a particularly elegant one. But this unassuming assembly, which contains 32 variable resistors, can learn to sort data like a machine-learning model. The potential energy savings works this way: Digital chips like GPUs expend energy per operation, so making a chip that can perform more operations per second just means a chip that uses more energy per second. In contrast, the energy usage of his analog computer is based on how long it is on. Should they make their computer twice as fast, it would also become twice as energy efficient. While its current capability is rudimentary, the hope is that the prototype will offer a low-power alternative to the energy-guzzling graphical processing unit (GPU) chips widely used in machine learning. (MIT Technology Review, Jun. 5, 2024, https://technologyreview.ae/source/how-a-simple-circuit-could-offer-an-alternative-to-energy-intensive-gpus/)

PCB Reliability

“Numerical Simulation Approach for Consideration of Ageing Effects in PCB Substrates by Modifying Viscoelastic Materials Properties”

Authors: Marius van Dijk, et al.

Abstract: During operating time of electronic systems, the materials used in such devices are potentially subjected to aging effects, which might limit the lifetime. Therefore, knowledge about the materials and the way they are affected by aging effects is of key importance to develop reliable products. This study discusses a simulation approach that can consider aging effects caused by oxidation at elevated temperature of a printed circuit board material, typically used for high-frequency applications. The material was characterized for its thermomechanical properties with state-of-the-art techniques for different aging durations. Aging was accelerated by storing the samples in an oven at 175°C for up to 1000 hr.

Within the simulation workflow, the thermomechanical properties of the different aged states are defined by modifying the pristine viscoelastic properties. Four exponential functions are derived modifying the initial modulus, the characteristic time constants, the shift function and the coefficient of thermal expansion, all in dependency of aging time.

To demonstrate the approach, the soldered interconnection lifetime of a theoretical chip-size-package on a printed circuit board is studied. State-of-the-art lifetime predictions of such interconnections only include thermomechanical aging effects, for example by creep effects of the solder. By additionally considering the aging of the printed circuit board, thermal aging is combined with thermomechanical aging.

Results in the soldered interconnection are compared between either considering additional aging effects of the printed circuit board or neglecting this behavior. Thus, it is shown that thermal aging plays a significant role in the development of accumulated creep strain which becomes increasingly important with increasing expected lifetime. (Microelectronics Reliability, June 2024, https://www.sciencedirect.com/science/article/pii/S0026271424000830)

Recycling

“Efficient and Selective Gold Recovery using Amine-Laden Polymeric Fibers Synthesized by a Steric Hindrance Strategy”

Authors: Youngkyun Jung, et al.

Abstract: Various alkylamines are commonly used for efficient Au recovery; however, their high hydrophilicity can result in dissolution in water, hindering effective Au recovery and potentially causing environmental contamination. Currently, the forms in which alkylamines are immobilized on supports provide unsatisfactory Au recovery capabilities and exhibit low structural stability. This study proposes a pragmatic approach for synthesizing amine-laden polymeric fiber (ALPF) adsorbents with efficient Au recovery capabilities and superior structural stability. Polyacrylonitrile fibers (PANF) were employed as a supportive matrix to immobilize the alkylamine molecules chemically. The densely grafted amine groups on the ALPF adsorbed significant amounts of Au ions and reduced them to Au(0) crystals. This chelation–precipitation hybrid method achieved a Au recovery efficiency of nearly 100% over a wide pH range of 1–4. In addition, it demonstrated an exceptional Au adsorption capacity of 1463 mg/g, surpassing the values reported for other adsorbents categorized by size and shape. Even in the presence of 14 different coexisting metal ions, the ALPF showed a Au recovery efficiency above 99.9%. It also exhibited excellent reusability, maintaining a Au recovery rate of ∼91% after 10 cycles. Furthermore, fibrous adsorbents alleviated the pressure drop in columns filled with adsorbents, thereby enabling energy-efficient and environment-friendly processes. (Chemical Engineering Journal, March 2024; https://doi.org/10.1016/j.cej.2024.149602)

Solder Materials

“Effect of Ce and Sb Doping on Microstructure and Thermal/Mechanical Properties of Sn-1.0Ag-0.5Cu Lead-Free Solder”

Authors: Fang Liu, et al.

Abstract: This study investigated effects of Ce and Sb doping on the microstructure and thermal mechanical properties of Sn-1.0Ag-0.5Cu lead-free solder. The effects of 0.5%Sb and 0.07%Ce doping on microstructure, thermal properties and mechanical properties of Sn-1.0Ag-0.5Cu lead-free solder were investigated. According to the mass ratio, the solder alloys were prepared from tin ingot, antimony ingot, silver ingot and copper ingot with purity of 99.99% at 400°C. X-ray diffractometer was adopted for phase analysis of the alloys. Optical microscopy, scanning electron microscopy and energy dispersive spectrometer were used to study the effect of the Sb and Ce doping on the microstructure of the solder. Then, the thermal characteristics of alloys were characterized by a differential scanning calorimeter (DSC). Finally, the ultimate tensile strength (UTS), elongation (EL.%) and yield strength (YS) of solder alloys were measured by tensile testing machine. With the addition of Sb and Ce, the ß-Sn and intermetallic compounds of solders were refined and distributed more evenly. With the addition of Sb, the UTS, EL.% and YS of Sn-1.0Ag-0.5Cu increased 15.3%, 46.8% and 16.5%, respectively. The EL.% of Sn-1.0Ag-0.5Cu increased 56.5% due to Ce doping. When both Sb and Ce elements are added, the EL.% of Sn-1.0Ag-0.5Cu increased 93.3%. The addition of 0.5% Sb and 0.07% Ce can obtain better comprehensive performance, which provides a helpful reference for the development of SAC lead-free solder. (Soldering & Surface Mount Technology, May 2024, https://www.emerald.com/insight/content/doi/10.1108/SSMT-08-2023-0044/full/html)