In Case You Missed It
Defect Detection
“A Novel YOLOv5_ES Based on Lightweight Small Object Detection Head for PCB Surface Defect Detection”
Authors: Yi Gao, et. al.
Abstract: In the manufacturing process of printed circuit boards (PCBs), surface defects have a significant negative impact on product quality. Considering that traditional object detection algorithms have low accuracy in handling PCB images with complex backgrounds, various types and small-sized defects, this work proposes a PCB defect detection algorithm based on a novel YOLOv5 multi-scale attention mechanism spatial pyramid dilated convolution (SPD-Conv) (YOLOv5_ES) network using improved YOLOv5s framework. First, the detection head is optimized by removing medium and large detection layers, leveraging the capability of the small detection head to identify minor target defects. This approach improves model accuracy and lightweighting. Second, to further reduce the number of parameters and computational costs, the SPD-Conv is introduced to improve feature extraction capability by reducing information loss. Third, an EMA module is introduced to fuse context information of different scales, enhancing the model’s generalization ability. Compared to the YOLOv5s model, there is a 3.1% improvement in mean average precision (mAP0.5), a 55.8% reduction in model parameters and a 4.8% reduction in giga floating-point operations per second (GFLOPs). These results demonstrate a significant improvement in both accuracy and model parameter efficiency. (Scientific Reports, October 2024, https://doi.org/10.1038/s41598-024-74368-7)
EMI Reduction
“Digital Active EMI Filter for Smart Electronic Power Converters”
Authors: Michele Darisi, et. al.
Abstract: Operation of electronic power converters, or the systems that interface with them, commonly produces undesired electromagnetic interference (EMI). This work presents a digital active EMI filter designed to mitigate such disturbances. The proposed hardware implementation can acquire and analyze the common-mode (CM) noise affecting the circuit and inject a compensation signal to attenuate the measured interference. A novel adaptive algorithm is introduced to compute the necessary signals for effective noise cancelation. The implementation is integrated within a single PCB interfaced with a field-programmable gate array (FPGA) running the control algorithm. The digital filter’s efficacy in EMI reduction is demonstrated using a synchronous buck converter with gallium nitride (GaN) power devices, achieving significant noise reduction. Additionally, potential functionalities are envisioned to fully exploit the capabilities of the proposal beyond EMI filtering, like fault detection, predictive maintenance, smart converter optimization, and communication. (Electronics, September 2024, https://doi.org/10.3390/electronics13193889)
Flexible Electronics
“Pressure-Constrained Sonication Activation of Flexible Printed Metal Circuit”
Authors: Lingxiao Cao, et. al.
Abstract: Metal micro/nanoparticle ink-based printed circuits have shown promise for promoting the scalable application of flexible electronics due to enabling superhigh metallic conductivity with cost-effective mass production. It is challenging, however, to activate printed metal-particle patterns to approach the intrinsic conductivity without damaging the flexible substrate, especially for high melting-point metals. The authors report a pressure-constrained sonication activation (PCSA) method of the printed flexible circuits for more than dozens of metals (covering melting points from room temperature to 3422°C) and even nonmetallic inks, which is integrated with the large-scale roll-to-roll process. The PCSA-induced synergistic heat-softening and vibration-bonding effect of particles can enable multilayer circuit interconnection and join electronic components onto printed circuits without solder within 1 sec. at room temperature. The authors demonstrate PCSA-based applications of 3-D flexible origami electronics, erasable and foldable double-sided electroluminescent displays, and custom-designed and large-area electronic textiles, thus indicating its potential for universality in flexible electronics. (Nature Communications, September 2024, https://doi.org/10.1038/s41467-024-52873-7)
Solder Alloys
“Criteria for Solder Alloy Adoption”
Authors: Deng Chen, et. al.
Abstract: Tin-lead alloys were historically the dominant solder used in printed circuit board assemblies. Tin-silver-copper (SAC) solder began to replace tin-lead starting in 2006 after European Union regulations banned use of lead for a wide range of electronic products. Despite the successful transition to tin-silver-copper lead-free solder and over 15 years of high-volume lead-free electronic production, a number of aerospace and defense products have not converted to SAC or other lead-free solders due to reliability concerns. Reliability should be a concern for all product manufacturers and end-users. This begs the question, what has convinced industries currently producing lead-free products that reliability was sufficient and what is keeping defense and aerospace electronic equipment manufacturers from adopting lead-free solder? This work reviews decision processes for adopting solder for printed circuit board assembly. (Journal of Surface Mount Technology, April 2024, https://doi.org/10.37665/smt.v37i1.41)
