Pad Design Research Articles

Optoelectronic Pressure Sensor Based on the Bending Loss of Plastic Optical Fibers Embedded in Stretchable Polydimethylsiloxane.

We report the design and testing of a sensor pad based on optical and flexible materials for the development of pressure monitoring devices. This project aims to create a flexible and low-cost pressure sensor based on a two-dimensional grid of plastic optical fibers embedded in a pad of flexible and stretchable polydimethylsiloxane (PDMS). The opposite ends of each fiber are connected to an LED and a photodiode, respectively, to excite and measure light intensity changes due to the local bending of the pressure points on the PDMS pad. Tests were performed in order to study the sensitivity and repeatability of the designed flexible pressure sensor.

A −31.7 dBm Sensitivity 0.011 mm2 CMOS On-Chip Rectifier for Microwave Wireless Power Transfer

This paper pursued both the lower operating power limit and small area of on-chip rectifiers for microwave wireless power transfer (MWPT). RF–DC charge pump rectifiers can operate in the fast switching limit at a high frequency of 920 MHz even with a small stage capacitor Cin of 100 fF, which contributes to an area reduction in the on-chip rectifiers. Circuit design starts with Cin determined as small as possible, followed by the determination of switching transistors and the number of stages. Even at an extremely low input power of 1 μW, wiring resistance in RF inputs is critical. Routing of the RF inputs is designed in line with stage capacitors. Bonding pad structure also affects the lower input power limit. Ground-shielded pad design can reduce the lower limit. Various types of RF–DC charge pump rectifiers are fabricated in 65 nm CMOS. An ultra-low-power diode RF–DC charge pump rectifier with 32 stages had a lower input power limit of −31.7 dBm at an output voltage of 1.0 V. Its small silicon area of 0.011 mm2 allows RF–DC rectifiers to be integrated in sensor ICs. More advanced technology providing MIM capacitors with higher capacitance density and placing switching MOSFETs under the MIM capacitors will further reduce the area of RF–DC charge pump rectifiers, allowing them to be integrated in sensor ICs.

Experimental and numerical study on the structural behavior of assembled interlocking lunar landing pad

Lunar landing pad is an important infrastructure on the lunar surface and is used to improve landing safety and mitigate dust problems caused by launch and landing. It will be subjected to the dynamic mechanical loading from the footpads of the spacecraft and the retrorocket plume loading. Only the former was considered in this study, and the latter will be explored in future studies. Prefabricated module assembly method is one of the most feasible construction methods. The assembly pattern, size, and thickness of the prefabricated modules are important factors that affect the structural performance of the lunar landing pad. In this study, three forms of mechanical interlocking were identified for an assembled lunar landing pad (ALLP) according to the interlocking form. In addition, a simple shape was designed for each form. Interlocking concrete blocks were fabricated, and a plate loading test (PLT) was conducted to evaluate the structural performance of the assembled concrete block pavement (ACBP). By comparing the numerical and experimental results, corresponding finite element (FE) models of the plate loading tests were developed and validated. Finally, an FE model to evaluate the structural performance of the ALLP based on the validated ACBP FE model was developed. The effects of the size and thickness of the interlocking modules and load position on the structural performance of the ALLP were further studied. The results indicated that the thickness of the modules had a greater influence on the structural performance than the load position and size of the modules. This study is expected to provide a reference for the design and construction of lunar landing pads.

Rapid detection of three mycotoxins in animal feed materials using competitive ELISA-based origami microfluidic paper analytical device (μPAD).

We report the development of a competitive ELISA-based origami microfluidic paper-based analytical device (μPAD) for the detection of mycotoxins in animal feed material. The μPAD was patterned using the wax printing technique with the design of a testing pad in the middle and two absorption pads at the side. Anti-mycotoxin antibodies were effectively immobilized on chitosan-glutaraldehyde-modified sample reservoirs in the μPAD. The determination of zearalenone, deoxynivalenol, and T-2 toxin in corn flour was successfully achieved by performing competitive ELISA on the μPAD in 20min. Colorimetric results were easily distinguished by the naked eye with a detection limit of 1µg/mL for all three mycotoxins. The μPAD integrated with competitive ELISA holds potential for practical applications in thelivestock industry for rapid, sensitive, and cost-effective detection of different mycotoxins in animal feed materials.

Challenges and Barriers of Wireless Charging Technologies for Electric Vehicles

Electric vehicles could be a significant aid in lowering greenhouse gas emissions. Even though extensive study has been done on the features and traits of electric vehicles and the nature of their charging infrastructure, network modeling for electric vehicle manufacturing has been limited and unchanging. The necessity of wireless electric vehicle charging, based on magnetic resonance coupling, drove the primary aims for this review work. Herein, we examined the basic theoretical framework for wireless power transmission systems for EV charging and performed a software-in-the-loop analysis, in addition to carrying out a performance analysis of an EV charging system based on magnetic resonance. This study also covered power pad designs and created workable remedies for the following issues: (i) how power pad positioning affected the function of wireless charging systems and (ii) how to develop strategies to keep power efficiency at its highest level. Moreover, safety features of wireless charging systems, owing to interruption from foreign objects and/or living objects, were analyzed, and solutions were proposed to ensure such systems would operate as safely and optimally as possible.

LOWNOISEPAD: Low-cost noise control by optimized rail pad: Feasibility study on the use of rail pad as noise mitigation measure

When aiming to minimize track noise, there is a significant conflict of aims that must be considered. Tracks with stiff rail pads are generally less noisy than ones with soft rail pads. Stiff rail pads, however, can decrease the long-term quality of the track. In order to achieve an optimum, beside stiffness also rail pad damping at relevant frequencies must be considered. The International Union of Railways (UIC) works with its members to better understand the noise-generation and rail pad effects. The LOWNOISEPAD project brings together the European railway community in an effort to find an optimal rail pad for both noise and track quality issues and for the different situations encountered in 12 European railway networks. Besides acoustic rail roughness, the stiffness and damping properties of rail fastening systems such as rail pads have a considerable influence on rail noise. In practice, rail pad design is always a compromise between track engineers' demand for flexibility and acoustic engineers' expectations for sufficiently high Track Decay Rate. The paper describes the measurements undertaken in the project, shows first conclusions as well as a software tool that allows determining noise levels after installing rail pads with given stiffness and damping properties.

An Empirical Survey on Wireless Inductive Power Pad and Resonant Magnetic Field Coupling for In-Motion EV Charging System

EVs are the recent emerging automotive technology in the transportation sector to reduce the CO2 emission from the internal combustion engine. The issues in EVs technology development are battery tube capacity, heavy-size batteries, fast charging, and safe charging infrastructure. The dynamic wireless charging technology shows a suitable alternative to address the charging system-related issues in EV. However, a limited number of review studies are conducted to specifically address the wireless charging pad design challenges. The wireless inductive power pad and magnetic coupling circuit design are the main factors to decide the performance of the DWPT system. This review analyzes the current developments and challenges associated with wireless charging pad design. Further, this study investigates the potential parameters which improve the performance of a DWPT system to increase the distance traveled (mileage). First, this paper discusses WRIPT technology for DWPT EV charging application, and several parameters affecting the PTE are examined. Also, the aids factors considered for designing the DWPT power pad and different magnetic resonance coupling topologies are presented. In addition, the performance evaluation of the WRIPT power pad, with in-motion testing from the major findings in earlier studies is discussed. Finally, the challenges and opportunities of the WRIPT power pad for in-motion EV charging applications are also addressed. The current state of the art of DWPT and its future directions to make DWPT EV charging systems a full-fledged method are highlighted.

Numerical Study on Stress Field of Knee Meniscus in Jumping Gait

In this paper, the numerical study focuses on the stress field of the knee meniscus in the two gaits of the jumping motion, and the knee injury and its knee protection effect are studied based on the stress field distribution characteristics of the knee meniscus. The jumping gait simulation was carried out by using a more detailed healthy knee model including bone, articular cartilage, meniscus, ligaments and peripheral soft tissues constructed by combining CT and MRI tomography, and the peak stress and its distribution area were analyzed based on the stress field characteristics of the meniscus, and the knee meniscus and its injury and protection under different knee pads were discussed. The results showed that the anterior angle of the meniscus on the medial knee joint was an area prone to injury in the take-off and landing gait. Under the knee pads, the peak stress of the meniscus decreases, and its distribution area gradually shifts from the anterior angle to the middle, and the functional knee pads with the optimized force load significantly alleviate the stress concentration of the meniscus. Therefore, the numerical study of the stress field of the knee meniscus provides theoretical support and optimization guidance for the design of functional knee pads.

Polishing pad design for uniform removal distributions in double-sided polishing

Due to the inevitable, nonuniform relative speed distribution between a workpiece and polishing pads, double-sided polishing (DSP) faces the challenge of nonuniform removal distributions. Hence, maintaining workpiece flatness while perfecting surface finishing remains a challenge in the DSP process. This study controlled the pressure distribution on a workpiece using a polishing pad design to compensate for the nonuniformity. An analytical model of the removal distribution was proposed considering the impact of pressure distribution. Experiments confirmed the proposed model's capability to evaluate the compensating effect of the polishing pad design. Finally, design guidelines for uniform removal distributions were established.

The Effect of Customized Insole Pads on Plantar Pressure Distribution in a Diabetic Foot with Neuropathy: Material and Design Study Using Finite Element Analysis Approach

To reduce the trial and error in a real clinical scenario, the finite element analysis (FEA) can be effectively used to simulate various effective pad designs and a material selection to reduce and redistribute peak plantar pressure in a diabetic foot with neuropathy. The aim of this study was to investigate the effect of pad design and material stiffness on the reduction in plantar pressure in a diabetic foot with neuropathy using FEA. Three-dimensional foot models with a customized insole (CMI) were created to study the peak contact pressure. Ethylene vinyl acetate, Nora® Lunalastike, and thermoplastic polyurethane were assigned to the top, middle, and base layers of the CMI, respectively. Two types of pads were proposed: a heel pad and a heel–forefoot pad. Four different materials with different stiffnesses were assigned as pad materials including a void pad. The FEA revealed that pads with soft materials reduced peak plantar pressure more effectively than stiffer pads. The use of a softer heel–forefoot pad reduced the peak plantar pressure at the midfoot and forefoot compared with other pads. The findings suggest that the material and design selection for the fabrication of CMIs with pads are important factors in reducing plantar pressure and may be useful in the management of a neuropathic diabetic foot.

Failure case analysis of fastening bolts for trolley rail of quay crane

This paper presents a premature failure analysis of bolts used for trolley rail fastening system of quay crane. The investigation included experimental and numerical analysis. Failure bolt inspection revealed the failure site was at the combination of thread run out and under-head-to-shank transition. Failure bolt chemical composition analysis shows no material and manufacturing defect. Fracture surfaces morphology of the failure bolts reveals premature fatigue fracture process. Structural health monitoring (SHM) and field test indicated the main failure cause are high strength impact due to trolley passing through rail gap because of worn rail pad and unreasonable design of rail clip. Numerical simulations have been conducted. The installation simulation of rail fastening system shows eccentricity loading condition of bolt due to incline of rail clip. Combined with field test of rail gap region vertical acceleration, the trolley rail system has been simulated via finite element analysis to illustrate the mechanism of bolt failure. Worn rail pad at rail gap region produced high level of impact load due to trolley passage. The influence of worn level of rail pad on bolt stress has been investigated. A modified design of rail clip is presented. The comparison of the original and modified rail fastening system as well as the elastic and rigid rail fastening system had been conducted.

Thermodynamic Modeling of the Advanced Geothermal System Using Inclined Well Applications

The advanced geothermal system (AGS), also called the closed-loop geothermal technology, requires extremely long horizontal wellbore completion to compensate the deficiency for conductive heat exchange in deep reservoirs, which is technically challenge. The AGS using inclined well configuration has been proposed to improve its efficiency, but it lacks a comprehensive and quantitative evaluation in public domain. In this study, analytical models based on Duhamel’s convolution and natural coupling methods are developed to evaluate the performance of the inclined configuration. The results suggest that the inclined wellbore system can improve the outlet temperature performance of a typical horizontal configuration by 16 %. The inclined system also shows a constant temperature gain (9 °C/km in this case study) for unit increment in lateral length. In multilateral applications of the inclined well system, our sensitivity tests indicate that wellbore spacing can have significant impact on the heat energy production performance due to wellbore interferences if the distance between wells is small in 3D space. At least a 50 m distance between any two wellbores is recommended for the multi-lateral wellbore system in the well pad design. In general, 20 % (3 MWth) more heat energy can be generated and almost 1000 GWhth more heat energy could be produced at the end of 30 years by using a standard 10-laterals inclined well system in our case study.

Unipolar Arc Ignited Partial Discharge for 650-V AlGaN/GaN HEMTs during the DC Breakdown Voltage Measurement

Without the Fluorinert solution and proper pad design, the high–voltage (HV) transistor used during the DC breakdown voltage (Vbk) measurement might be damaged by the partial discharge (PD) in the air if its Vbk is close to one thousand volts or more. From the waveform measurement, the PD in the air occurred at 650 V HV GaN HEMTs during the Vbk measurement, it is ignited by the unipolar arc, and it is not ignited by the avalanche breakdown. This is based on the fact that the current falls below zero ampere to become a negative current, and the voltage rises so that it is higher than the setting voltage of the DC meter at the onset of the PD, thus corresponding with the electrons, leaving the plasma to cathode, and enabling a build–in potential to exist in the plasma. Then, the PD ignites because the current starts to rise in order to allow for a positive spike current; the voltage level subsequently falls and a lower voltage reading is obtained.

P‐8.5: Research on LED Pad Design in Glass‐based Mini LED Backlight

In the past two years, the field of glass-based mini LED backlight has developed rapidly. In this article, experimental research on the design of the LED pad is conducted, including the Cu thickness, stack-up structure and pad size. The experimental results show that after the LED is solidified, the copper at the bonding pad is consumed and intermetallic compounds (IMC) are formed. The IMC has a granular morphology, dispersed in the solder layer. The main components of IMC are Cu6Sn5 and Ag3Sn. When the copper thickness on the pad increases from 0.6um to 3.6um in turn, the proportion of IMC in the solder layer increases significantly. The formation of IMC can improve the connection strength, but too much IMC will reduce the mechanical strength and the rework times. The fundamental method is to suppress the reaction rate of the Cu layer and the SnAgCu solder. The Electroless Nickel Immersion Gold (ENIG) process is a feasible method, because the Ni layer can effectively reduce the formation rate of IMC, and Au layer can effectively prevent the Cu of the LED pad from being oxidized. In addition, when the expansion of the BP pad relative to the LED bump increases, the die bonding yield is also significantly improved. These verification results could provide reference for future mini LED product design and production.

Football Shoulder Pad Design and Its Effect on Head Kinematics in Shoulder-to-Helmet Impacts.

Shoulder-to-helmet (STH) impacts have been shown to cause approximately twenty percent of concussions in football yet little research has investigated shoulder pad design and STH impacts. This study aimed to characterize STH impacts and identify the effect of shoulder pad design on the struck head kinematics. Additional padding was added to a shoulder pad, and was then compared to an unmodified control shoulder pad. Participants performed a series of tests where they struck a helmeted Hybrid III dummy with both shoulder pad variations to compare struck head linear and rotational kinematics. The study found the modified shoulder pad reduced peak linear acceleration by 31% (Δµ = -9.13g's (-∞, -7.25), (p = 4.10e-08)), rotational acceleration by 28% (Δµ = -565rads-2(-∞, -435), (p = 2.10e-07)), peak rotational velocity by 10% (Δµ = -2.42rads-1 (-∞, -1.54), (p = 6.9e-05)), and increased impact duration by 40% (Δµ = 9.96ms (8.06, ∞), (p = 1.142e-08)). Impact response corridors were developed for both shoulder pad conditions and can be used to establish a controlled lab test setup that replicates STH impacts. Our findings suggest that shoulder pads have the potential to reduce head injury in football and warrant further research.

Approach With Simple Tools Enables Well-Spacing Optimization for Unconventionals

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 208882, “No Reservoir Model? No Problem. Unconventional Well Spacing Optimization With Simple Tools,” by Patrick Miller, SPE, Darcy Redpath, SPE, and Keane Dauncey, SPE, Petronas. The paper has not been peer reviewed. _ Optimizing economics for unconventional resource development is a delicate balance. To search for the optimal pad design, operators often invest in integrated technical work flows with multiwell fracture modeling and reservoir simulation. Although useful, these work flows are not practical for every asset in a portfolio because they simply take too long. As an alternative approach, the complete paper builds on existing tools in the literature to quantify the effect of changing well spacing on well productivity for a given completion design, using a new, simple, intuitive empirical equation. Methodology: Understanding Well-Performance Changes With Well Spacing The four key drivers of pad economics for unconventional plays are commodity prices, reservoir deliverability, completion design, and well spacing. Completion design and well spacing must be considered together because the drainage area of an unconventional well is driven by the size of the fracture stimulation. Finding the global maximum of the optimization criteria with traditional technical work flows is intensive in terms of human resources and time. Furthermore, these traditional work flows are still only estimates of well performance under different conditions. This section of the complete paper provides a set of visual references for what is happening in the subsurface when well spacing is changed for a given fracture stimulation design and then discusses how this can be represented mathematically. The goal of the authors, in discussing currently used approaches, is to set the background for an alternative, easy-to-understand approach to define shared reservoir factor (SRQ) as a function of well density in a way that creates the expected concave down shape initially but which transitions to a linear relationship and trends toward a relative estimated ultimate recovery (EUR) of 0% at 0 well spacing. The methodology of this approach is provided mathematically in this section of the complete paper.

Source Pad Design Tradeoffs for a Power TrenchFET

This paper will demonstrate wirebond pad design considerations for the source pad of a power trenchFET using three levels of metal. There will be a discussion of how the pad design will impact the pad mechanical strength through the bonding process. Both Aluminum-Copper (AlCu) and Damascene Copper power metals have been investigated. There will also be a comparison of bondpad design to electrical simulation results. An optimal design can be obtained by an analysis of these tradeoffs. Finally, the proposed designs have been built on silicon and evaluated both mechanically and electrically concluding with the best design found for this application.

3-D Analytical Model of Bipolar Coils With Multiple Finite Magnetic Shields for Wireless Electric Vehicle Charging Systems

The bipolar pad is one of the most promising topologies in inductive power transfer (IPT) systems for electric vehicles. However, there is scant literature on the analytical model of the bipolar pad. In this article, a three-dimensional (3-D) analytical model of the IPT system including a bipolar transmitter and a square receiver is developed based on the superposition of two 2-D subdomain analytical models. Ferrite and the aluminum shields with finite dimension are taken into account on the transmitter and receiver sides. An analytical calculation of the mutual inductance is then carried out with respect to the main parameters of the IPT system, namely the dimension of the coils, the conductivity, and the permeability of the shield. Three study cases are demonstrated to highlight how the proposed method can accelerate speed up the pad design process. Calculation results of the proposed model are compared with both a finite-element analysis (FEA) model and experimental measurements, demonstrating that the proposed model is nine times faster than the FEA method. When comparing with the experimental results, computational error of the proposed model is less than 6% in most of the study cases.

Toward reducing no-clean flux spatter during reflow soldering: Investigating the effect of flux type, solder mask, and solder pad design

This comprehensive study dealt with the reliability issue of no-clean flux spattering from the solder paste during the reflow soldering process. Several factors entering the process were investigated: the type of flux in the solder paste (ROL0/ROL1 according to the IPC J-STD-004B standard), the type of solder mask (liquid photo imageable/directly printed), and the type of solder pad design (copper-defined/solder mask-defined). A unique design of the test board was developed for a proper evaluation of flux spatter spots spattered from the solder paste. The testing board included real-sized soldering pads and a boron-silicate glass slide as a target area, ensuring the same evaluation process for all samples. The results showed a strong influence of flux chemistry on spattering. Changing the flux from ROL1 to ROL0 reduced the flux spot occurrence by 62 % on average. The type of solder pad design also slightly affected the flux spattering. No significant difference was found between the used solder masks; therefore, it is possible to use the novel, directly printed one without increasing the risk of flux spattering.

Effect of the IMC layer geometry on a solder joint thermomechanical behavior

PurposeIn a printed circuit board assembly (PCBA), the coefficient of thermal expansion (CTE) mismatch between the solder joint materials has a detrimental impact on reliability. The mechanical stresses caused by the thermal changes of the assembly lead to fatigue and sometimes the failure of the solder joints. The purpose of this study is to propose a novel pad design to obtain an interrupted solder/substrate interface, to improve the PCBA reliability.Design/methodology/approachAn interruption in the continuous intermetallic compound (IMC) layer of a solder joint was implemented, by the deposition of a silicone film in the pad, changing its geometry. That change allows a redistribution of stresses in the most ductile zone of the solder joint, the solder. The stress concentration at the solder/substrate interface is reduced, as well as the general state of stress at the solder joint.FindingsA new way was developed to reduce the stress on the solder joints, caused by thermal variations, because of the different components CTEs mismatch. This new method consists of interrupting the IMC layers of the solder joint, strategically, redirecting the usual stresses to a more ductile area of the joint, the solder. This is an innovative method that allows increase the lifetime of PCBAs and the equipments.Originality/valueIn this study, a new pad design concept for higher solder joint reliability was developed to reduce the shear stress in the solder joints because of the CTE mismatch between all the solder joint components.