In Case You Missed It

Soldering

“Modeling the Effects of Thermal Pad Voiding on Quad Flatpack No-Lead (QFN) Components”

Authors: Ross Wilcoxon, et. al.

Abstract: Finite element modeling was used to evaluate the effects of thermal pad solder voiding on the thermal resistance of quad flatpack no-lead components. This included two different approaches for modeling solder voids: many small, distributed voids, the effects of which were averaged across the entire solder contact area, or a single discrete void. Two approaches were used for defining the thermal path established in the solder. Effects of other design parameters – thermal boundary conditions, the presence of thermal vias under the package, and the size of the die power dissipation area – were also addressed. Modeling showed that thermal vias and external boundary conditions had the most significant impact on the package thermal resistance. Solder pad voids and concentrated die-level heat dissipation, for the range used in this study, had noticeable but less significant impacts on thermal resistance. The study also compared different approaches for simulating solder voiding and identified ranges in which modeling simulations are most appropriate. (Journal of Surface Mount Technology, July 2023, https://doi.org/10.37665/smt.v36i2.37)

Surface Finishes

“Development of Cost-Effective Ni-Less Surface Finishing Process for High-Speed PCBs”

Authors: Jaeseong Park, et. al.

Abstract: The growing need to use low-power and high-frequency signals for the high-speed transmission of large-capacity data is driving the demand for suitable printed circuit boards. Most printed circuit boards use Cu as a conducting material and require a surface finish that forms an organic or a metallic protective layer on the Cu surface to prevent Cu diffusion/oxidation. Metallic protective layers typically have a higher resistivity than Cu, resulting in significant signal transmission losses in the high-frequency range. For example, electroless Ni/electroless Pd/immersion Au (ENEPIG), a surface finish that forms a metallic protective layer, sequentially forms Ni-P, Pd-P, and Au layers on a Cu surface. Among these, the Ni-P layer is the main cause of signal transmission loss owing to its high resistivity. In this study, the authors developed immersion Ag/immersion Pd/immersion Au (ISIPIG), a cost-effective surface finishing process that does not form a Ni-P layer. ISIPIG effectively prevented the diffusion/oxidation of Cu and improved solder wettability while exhibiting a lower insertion loss and higher antenna efficiency than ENEPIG. The authors’ results suggest that ISIPIG is a promising surface finishing process for applications that require the high-speed transmission of large-capacity data using low-power and high-frequency signals. (Journal of Electronic Materials, August 2023, https://doi.org/10.1007/s11664-023-10616-2)

Sustainability

“Recycling And Sustainable Applications of Waste Printed Circuit Board in Concrete Application and Validation Using Response Surface Methodology”

Authors: M. Vishnu Priyan, et. al.

Abstract: The present investigation aims to examine the mechanical and durability properties of concrete that has been reinforced with a waste printed circuit board (WPCB) toward a low-carbon-built environment. It assessed the fresh and hardened characteristics of the low-carbon concrete reinforced with WPCB fibers, after a curing period of seven and 28 days. The evaluation was done by quantifying slump, compressive strength, split tensile strength, flexural strength, sorptivity, rapid, and acid tests. It further analyzed 11 discrete concrete mixes with WPCB fibers at a weight percentage ranging from 1 to 5% in the cement mixture. The results indicate that incorporating WPCB fiber into concrete improves its mechanical strength. The results revealed that incorporating 5% WPCB fiber yielded the most favorable outcomes. The properties of WPCB fiber-reinforced concrete have been theoretically validated through response surface methodology (RSM), which employs various statistical and mathematical tools to analyze the experimental data. The results derived from RSM were compared with the experimental results. The RSM model demonstrated a high level of accuracy (R2≥0.98) in validating the mechanical properties of WPCB fiber concrete. The statistical model exhibited no indication of prediction bias and demonstrated a statistically significant outcome, with a p-value below 0.5. (Scientific Reports, October 2023, https://doi.org/10.1038/s41598-023-43919-9)

Thermal Management

“Influence of a PCB Layout Design on the Efficiency of Heat Dissipation and Mutual Thermal Couplings between Transistors”

Authors: Krzysztof Górecki and Krzysztof Posobkiewicz

Abstract: This article presents results of investigations concerning the influence of the printed circuit board (PCB) layout design on self and transfer transient thermal impedances characterizing thermal phenomena occurring in the network containing two power Mosfets. The tested devices have the case D2PAK and are soldered to the PCB using surface mount technology (SMT). The measurement method is described. The tested transistors are presented with the PCBs on which they are mounted. Measurement results of the tested transistors operating on all tested PCBs are shown and discussed. The influence of a cooling area of the tested PCBs on the parameters describing self and transfer transient thermal impedances is analyzed. (Electronics, October 2023, https://doi.org/10.3390/electronics12194116)