Printed Circuit Board Structure Research Articles

Design and experiment of high-field asymmetric waveform ion mobility spectrometry chip based on an integrated temperature control printed circuit board structure.

During the detection of volatile organic compounds (VOC) using high-field asymmetric waveform ion mobility spectrometry (FAIMS), the ambient temperature significantly impacts the accuracy of planar FAIMS. To mitigate the influence of ambient temperature on detection accuracy and enhance resolution, a FAIMS system based on the inner impedance characteristics of a printed circuit board (PCB) was designed for temperature control. This study, conducted under standard atmospheric pressure, aimed to assess the signal stability of a planar FAIMS instrument with and without temperature control, and the effect of temperature change on the detection ability of acetone, ethanol, and their mixture was studied using PCB self-heating. Experimental results demonstrated that the base noise in FAIMS with temperature control was 0.2pA, whereas that in FAIMS without temperature control was 1.8pA. Notably, with increasing temperature, the detection ability of FAIMS changes accordingly. The optimal relative detection ability of acetone was observed when the electrode plate was heated to 45°C under an electric field of 15 kV/cm. This study provides a novel approach to improve the resolving power of FAIMS systems and their signal-to-noise ratio. The utilization of a PCB-based temperature control proved effective in stabilizing FAIMS signal characteristics and optimizing detection capabilities, particularly for VOCs such as acetone. These findings have significant implications for improving the accuracy and resolving power of FAIMS systems in VOC detection applications.

A mechanistic study identifying improved technology critical metal delamination from printed circuit boards at lower power sonications in a deep eutectic solvent

Deep eutectic solvents (DESs) are an emerging class of ionic liquids that offer a solution to reclaiming technology critical metals (TCMs) from electronic waste, with potential for improved life cycle analysis. The high viscosities typical of DESs, however, impose mass transport limitations such that passive TCM removal generally requires immersion over extended durations, in some cases in the order of hours. It is postulated that, through the targeted application of power ultrasound, delamination of key structures in electronic components immersed in DESs can be significantly accelerated, thereby enabling rapid recovery of TCMs. In this paper, we fully characterise cavitation in a Choline Chloride-Ethylene Glycol DES as a function of sonotrode input power, by the acoustic detection of the bubble collapse shockwave content generated during sonications at more than 20 input powers over the available range. This justifies the selection of two powers for a detailed study of ultrasonically enhanced TCM-delamination from printed circuit boards (PCBs). Dual-perspective high-speed imaging is employed, which facilitates simultaneous observation of TCM removal, and the cavitation evolution and interaction with the PCB surface. Bubble jetting is identified as a key contributor to initial pitting of the TCM layers, exposing the larger underlying copper layer, with the contributions of additional inertial cavitation-mediated phenomena such as bubble-collapse shockwaves also demonstrated as important for delamination. Optimal cavitation activity throughout the sonication then promotes etching of the copper base layer of the PCB structure targeted by the DES, liberating the overlaying TCMs in sections as large as 0.79 mm2. We report a thirtyfold improvement in processing time compared to passive delamination, with sonications at the lower power outperforming those at the higher power. The results demonstrate the potential for industrially scalable recovery of TCMs from the growing quantities of global e-waste, using combined power ultrasonics and DESs.

Analysis of Typical PCB Vibration Characteristics Based on Modal Simulation and Experiment

This study combines simulation and experimental methods to explore the vibration characteristics of a servo controller printed circuit board (PCB). CREO is used to build a simulation model based on PCB structure analysis. ANSYS was used to perform finite element simulation analysis of vibration characteristics. The hammering method is used to perform circuit board modal experiments. By comparing the results of simulation and experimentation, the PCB dynamic characteristics are analyzed. It was found that the fixed frequency error of the simulation and the experiment is within 6%, and the first three mode shapes are consistent. Hence, it is suggested to use the simulation model for the subsequent vibration reliability analysis of the electronic product.

Wireless-controlled cubic neural stimulator for free-moving animals.

An electrical stimulator transmitting information into selected neural circuits is a promising approach for neural prostheses or animal robots. However, traditional stimulators are based on rigid printed circuit board (PCB) technology; technological limitations hindered the development of stimulators, especially for experiments involving free-moving subjects. Here we described a small (1.6 × 1.8 × 1.6 cm), lightweight (4 g, including a 100 mA h lithium battery) and multi-channel (eight unipolar or four bipolar biphasic channels) cubic wireless electrical stimulator exploiting flexible PCB technology. In comparison with the traditional stimulator, an appliance of both flexible PCB and cube structure makes it smaller and lighter, and enhances its stability. Stimulation sequences can be constructed with 100 selectable current levels, 40 selectable frequency levels and 20 selectable pulse-width-ratio levels. Moreover, the distance of wireless communication can reach approximately 150 m. Both in vitro and in vivo results have demonstrated functionality of the stimulator. The feasibility of remote pigeon's navigation using the proposed stimulator was successfully verified.

A New Integrated Active EMI Filter Topology With Both CM Noise and DM Noise Attenuation

Integration of electromagnetic interference (EMI) filters is a good idea to further decrease the volume and weight of a power converter. However, the conventional research articles mainly focus on the integration of passive components or planar printed circuit board structures. This article proposes a new integrated active EMI filter (AEF) topology. It can attenuate both common-mode (CM) and differential-mode (DM) noise at the same time. Different from the traditional discrete CM AEFs and DM AEFs, noise sensing and cancelation of this proposed topology are performed simultaneously. The working principle and special features of this topology are analyzed in detail. Based upon the theoretical analysis, the insertion loss of this integration topology is close to the traditional separated CM AEFs or DM AEFs. Besides fewer components and dc power supply are demanded. A prototype is built and tested through experiments. Experimental results derived on standard test board and practical converter show good agreement to theoretical analysis.

Efficient DC and AC Impedance Calculation for Arbitrary-Shape and Multilayer PDN Using Boundary Integration

This article presents an efficient methodology based on boundary integration to calculate the dc and ac impedance of power distribution networks (PDNs) for arbitrary-shape and multilayer printed circuit boards (PCBs). The proposed method adopts a boundary element method to extract inductances for the arbitrary parallel-plane shapes. Subsequently, the equivalent circuit formed by the via inductances and plane capacitances is solved using the node voltage method. By merging the parallel and serial inductances and simplifying the equivalent circuit, the computation time can be significantly reduced for a large number of vias and layers. This matrix manipulation strategy can be applied to various PCB structures without human intervention or commercial circuit solvers. Moreover, a contour integral method is employed to calculate the dc resistances for arbitrary shape and multilayer PDNs. Therefore, the wideband PDN impedance from dc to ac frequencies can be efficiently calculated through 1-D boundary integration, which can be performed more quickly than full-wave simulations. The proposed method can aid in the development of electronic design automation tools for PDN design.

Air cavity-based vibrational piezoelectric energy harvesters

Introduction. Known vibrational energy harvesting methods use a source of vibration to harvest electric energy. Piezoelectric material works as a sensing element converted mechanical energy (vibration) to electrical energy (electric field). The existing piezoelectric energy harvesting (PEHs) devices have low sensitivity, low energy conversion, and low bandwidth. The novelty of the proposed work consists of the design of PEH’s structure. Air cavity was implemented in the design where it is located under the sensing membrane to improve sensitivity. Another novelty is also consisting in the design structure where the flexural membrane was located at the top of electrodes. The third novelty is a new design structure of printed circuit board (PCB). The purpose of improvised design is to increase the stress in between the edges of PEH and increase energy conversion. With the new structure of PCB, it will work as a substrate that absorbs surrounding vibration energy and transfers it to sensing element. Methods. Three techniques were successfully designed in PEH and fabricated namely PEH A, PEH B, and PEH C were characterized by two experiments: load and vibration. The load experiment measured load pressure towards the PEH, whereas the vibration experiment measured stress towards the PEH. Results. PEH C has the highest induced voltage for a weight of 5.2 kg at the frequency of 50 Hz and the highest stored voltage for a period of 4 min. The three techniques applied in PEHs were showed improvement in transducer sensitivity and energy conversion. Practical value. A piezoelectric acoustic generator was used in the experiment to compare the performance of the designed PEH with available piezoelectric transducers in the market. The new flexible membrane worked as a sensing element was worked as a cantilever beam. PVDF was used as a sensing element due to the flexibility of the polymer material, which is expected to improve sensitivity and operating bandwidth.

Electromagnetic Compatibility Analysis and Optimization Design of Switching Power Supply Printed Circuit Board

Printed Circuit Board (PCB) is not only an important electrical module of information equipment, but also an important source of electromagnetic radiation. Only when PCB works normally and is compatible with other electrical equipment, the whole information equipment can work normally. Because of the complexity of PCB structure and the difficulty of modeling, the EMC (Electromagnetic Compatibility) analysis of PCB is very difficult. For this reason, Taking the widely used full bridge current double rectifier converter as an example, aiming at the electromagnetic compatibility problems caused by the PCB design of the switching power supply, this paper proposes a simulation method based on the electromagnetic field by establishing the near-field radiation model of the PCB, analyzes the areas with high radiation intensity in the PCB layout, by optimizing the layout and wiring of the PCB, the electromagnetic compatibility performance of the switching power supply is improved. The simulation results show that the near-field radiation characteristics of PCB can be predicted by introducing the electromagnetic field simulation method in the design stage, according to the characteristics of the magnetic field, the optimal design is realized, so that the EMC of the switching power supply reaches the standard, and finally the working performance of the switching power supply is improved.

Performance Enhancement of Capacitive-Type Torque Sensor by Using Resonant Circuit

This article proposes a method for improving the resolution of a capacitive-type (C-type) torque sensor. This method amplifies the output signal variation of a capacitance-to-digital (CDC) chip by designing a series-resonant circuit. This study considers the data sampling method of the CDC chip and the effects of the resonant circuit on the output signal. The CDC chip employs a switched-capacitor (SC) integrator for data sampling. The SC integrator was simulated to estimate the amplification of the output signal by the resonant circuit. The inductance and resistance of the resonant circuit are designed to optimize the sensor performance. As the SC integrator is commonly used in CDC chips, the proposed method is adaptable to a majority of existing C-type sensors. When fabricating the sensor, it is important to obtain the designed capacitance for implementing the resonant circuit. We design printed circuit board structures that can accurately obtain the designed gap between sensor electrodes and the ground. Artificial neural network is used for sensor calibration process. To prove the effectiveness of these methods, the performance of a sensor equipped with the resonant circuit was compared to that of a previously developed sensor.

Use of the Rotating Rectifier Board as a Capacitive Power Coupler for Brushless Wound Field Synchronous Machines

Wound field synchronous machines (WFSMs) are an attractive alternative to permanent magnet synchronous machines (PMSMs) given their competitive power/torque density and direct field excitation control for easy weakening. Here, a design process is presented for a low-cost and contactless capacitive power coupler (CPC) for WFSM rotor winding excitation using only simple printed circuit boards (PCBs). These PCBs are an extension of the machine’s rotating rectifier. Experimental verification of the design shows 675-W power transfer at 90.3% efficiency to the rotor field of a 30/55 kW (continuous/peak) WFSM operating as a generator. A GaN inverter switching at 2 MHz reduces passive component sizes and keeps CPC voltages within safe limits. Parasitic loss minimization design rules for trace layout in the CPC PCB structure are established for high-frequency operation along with a partial capacitance approach for the coupling matrix. Tank inductor loss was reduced by using a cored design, while a buck converter integrated into the rotating rectifier matches the load impedance of the rotor to the CPC system, reducing the complexity of the tank compensation circuit. Finally, the CPC as a platform for position self-sensing is introduced conceptually using two methods. First, a phase-locked loop (PLL) tracks the resonant tank frequency of the CPC, whose saliency is spatially tied to the rotation of the machine. Second, the rotating buck converter effectively injects high-frequency content into the field that can be tracked by the stator drive controls.

High Directivity Fabry–Perot Antenna With a Nonuniform Partially Reflective Surface and a Phase Correcting Structure

In this communication, a superstrate for the high radiation performance of a Fabry-Perot antenna (FPA) is proposed that consists of a nonuniform partially reflective surface (NPRS) and a phase correcting structure (PCS). The NPRS and the PCS function to uniformize the amplitude and phase distributions, successively, of the FPA's aperture field, thereby achieving a high directivity and a high aperture efficiency. Due to the independent amplitude and phase manipulations, the antenna design procedure is relatively rapid and effective. As a proof of concept, an FPA sample at an operating frequency of 5.8 GHz with a diameter of 200 mm is designed. The NPRS, comprising metallic square rings with dissimilar dimensions printed on a printed circuit board (PCB), is designed according to the leaky-wave method. A two-layer PCB structure is adopted as the PCS, which is designed by the transmission line model integrated with full-wave simulations. The FPA with the NPRS and the PCS is fabricated and measured for verification. The simulated and measured results are in good agreement. The directivity of the FPA with the proposed superstrate is 21.49 dB and the corresponding aperture efficiency is as high as 95.49% at 5.8 GHz.

Liquid-Crystal-Embedded Aperture-Coupled Microstrip Antenna for 5G Applications

This letter presents a novel reconfigurable microstrip antenna with a frequency of 28 GHz and an embedded liquid crystal (LC). First, a novel fabrication process that employs a heat press machine is developed. This allows for the successful creation of thin substrates with thicknesses ranging between 0.13 and 0.25 mm. It is validated that the proposed stacked topology achieves a wide tunable range of resonant frequency. In addition, a simple bias configuration is achieved by connecting the bias position to the middle of the patch, where radio frequency (RF) potential is zero. The proposed antenna adopts a three-layer stacked printed circuit board (PCB) structure to render a cavity in which the LC is injected. The bottom patch of the top substrate is designed to contact the LC, and thus, it simultaneously functions as a dc bias electrode and a radiating element. In addition, unlike conventional stacked patch antennas, the additional patch on the top of the PCB structure is tuned to enhance gain. Compared with the simulated performance of a prior LC-based antenna, the tunable range of the resonant frequency of the proposed antenna is improved by more than three times at a center frequency of 28 GHz and the peak radiation efficiency is improved by up to 17%. Furthermore, the area (252 mm2) of the proposed LC-based antenna is 40% of the area of the prior LC-based antenna (625 mm2).

High-Speed Printed Circuit Boards: A Tutorial

Circuit designers often tend to overlook Printed Circuit Board (PCB) designs. Circuits performance and the quality of measurements, however, are strongly correlated with careful and comprehensive PCB design techniques. Such design techniques are applicable to practically all circuits areas including analog, digital, RF, and power applications. This paper provides a fundamental understanding of common problems faced in designing high-performance and high-speed PCBs. While this tutorial paper does not cover basics of PCBs, it presents empirical and commonly practiced methods to deliver professional layouts. This includes studying on-board transmission lines and their matching techniques, various PCB structures that ensure good signal integrity, and bypass capacitors, for circuits up to 30 GHz. Conclusions and suggestions are justified with theoretical analysis and supported by simulations and measurements.

Flexible printed circuit board magnetic micromirror for laser marking/engraving

This paper presents a flexible printed circuit board (PCB) quasi-static magnetic micromirror, on which a portable laser marking/engraving machine is built. The micromirror consists of a flexible PCB structure (including two polyimide torsion beams, a middle seat with coils, and two support pads), two permanent magnets, and a mirror plate. The fabrication uses a flexible PCB process, in addition to dicing a silicon wafer for making the mirror plate. The mirror plate is bonded to the flexible PCB middle seat, which has high strain strength (maximum strain at yield ~3%) and high bonding yield with easy operation. The flexible PCB micromirror achieves a large quasi-static rotation, e.g. 13° (optical), a low driving voltage (−0.4– + 0.4 v), and a low cost (a few dollars). Its aperture is large (4 × 4 mm) with high flatness (radius of curvature, ROC of ~10 m). A prime method is proposed to address the drift/creep problem associated with the flexible PCB micromirror’s quasi-static rotation. A low cost and portable laser marking/engraving machine is built with the following performance: working area (22 × 17 mm2), size (116 × 43 × 55 mm3), laser power (0.23 W), speed 2 mm s−1.

Testing of Current Carrying Capacity of Conducting Tracks in High Power Flexible Printed Circuit Boards

In high power electronic applications, the current carrying conducting tracks of the printed circuit board (PCB) and the components generate heat. For the proper working of the circuit, this heat must be expelled to the surroundings. In flexible PCBs, heat sinks cannot be used for reducing the temperature. We developed a multilayer flexible PCB structure that includes a heat conducting thick layer and electrically non-conducting thin film layer. In this paper, we have tested a flexible PCB for high power applications and evaluated its performance when the current flows through the conductive tracks in it. The heat generated by current flowing through the copper conducting tracks of the PCB at different current conditions and its convection is analyzed in relation to board dimensions and structure. The ANSYS Workbench is used to test the temperature and current capabilities of the PCB. The test results show that the temperature of the flexible PCB gets reduced as the area of convection increases. In addition, the current carrying capacity of tracks in the flexible PCB is also increased. The high-power handling flexible PCB will help the heavy power electronics boards to reduce size and give PCB designers more freedom to design a layout fitting any shape of the cabinet of the device.

Wideband, Low-Profile Patch Array Antenna With Corporate Stacked Microstrip and Substrate Integrated Waveguide Feeding Structure

In this communication, a corporate stacked microstrip and substrate integrated waveguide (SIW) feeding structure is reported to be used to broaden the impedance bandwidth of a 4 × 4 patch array antenna. The proposed array antenna is based on a multilayer printed circuit board structure containing two dielectric substrates and four copper cladding layers. The radiating elements, which consist of slim rectangular patches with surrounding U-shaped parasitic patches, are located on the top layer. Every four radiation elements are grouped together as a 2 × 2 subarray and fed by a microstrip power divider on the next copper layer through metalized blind vias. Four such subarrays are corporate-fed by an SIW feeding network underneath. The design process and analysis of the array antenna are discussed. A prototype of the proposed array antenna is fabricated and measured, showing a good agreement between the simulation and measurement, thus validating the correctness of the design. The measured results indicate that the proposed array antenna exhibits a wide |S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> | <; -10 dB bandwidth of 17.7%, i.e., 25.3-30.2 GHz, a peak gain of 16.4 dBi, a high radiation efficiency above 80%, and a good orthogonal polarization discrimination of higher than 30 dB. In addition, the use of low-profile substrate in the SIW feeding network makes this array antenna easier to be integrated directly with millimeter-wave frontend integrated circuits. The demonstrated array antenna can be a good candidate for various Ka-band wireless applications, such as 5G, satellite communications and so on.

Signal Integrity Analysis of Integrated Circuits by Using Embedded Domain Decomposition Method

In integrated circuit designs, adjustments and replacements of components are frequently required for analyzing or improving signal integrity. However, the modifications of geometry will cause remeshings and resimulations in the full-wave analysis. Consequently, the design efficiency can be impaired due to repeated discretizations. In this paper, we introduce an embedded domain decomposition approach to address such repetitive simulations. A problem is first decomposed into a simpler background subdomain and multiple embedded subdomains. The geometrical details of interest can be placed into the embedded subdomains while the background subdomain covers the rest. Afterward, the communications between the subdomains are built by imposing coupling sources that represent field continuities, material polarizations, and surface currents on perfect electric conductor and port. The meshes between the subdomains are completely nonconformal, and the modification of an embedded subdomain will not affect the geometries and discretizations in the other subdomains. Such flexibility can be exploited in simulating complicated 3-D printed circuit board structures or investigating different components in an electronic system, as illustrated in the numerical examples.

Reactive material jetting of polyimide insulators for complex circuit board design

Polyimides are a group of high performance thermal stable dielectric materials used in diverse applications. In this article, we synthesized and developed a high-performance polyimide precursor ink for a Material Jetting (MJ) process. The proposed ink formulation was shown to form a uniform and dense polyimide film through reactive MJ utilising real-time thermo-imidisation process. The printed polyimide film showed a permittivity of 3.41 and degradation temperature around 500 °C, both of which are comparable to commercially available polyimide films. Benefiting from the capability of being able to selectively deposit material through MJ, we propose the use of such a formulation to produce complex circuit board structures by the co-printing of conductive silver tracks and polyimide dielectric layers. By means of selectively depositing 4 μm thick patches at the cross-over points of two circuit patterns, a traditional double-sided printed circuit board (PCB) can be printed on one side, providing the user with higher design freedom to achieve a more compact high performance PCB structure.

Codesign of Electrostatic Discharge Protection Device and Common Mode Suppression Circuit on Printed Circuit Board

A codesign of an electrostatic discharge (ESD) protection device and a common-mode suppression circuit on printed circuit board (PCB) for high-speed input/output interfaces is introduced in this paper. The characteristic and the circuit model of the ESD protection device are investigated and applied into the design of the common-mode suppression circuit. The proposed one-stage design of two-layered PCB structure performs –10-dB common-mode noise suppression from 2.22 to 2.76 GHz; the proposed two-stage design with additional common-mode suppression unit performs wideband suppression from 2.25 GHz to over 8 GHz, covering IEEE 802.11ac WiFi band with –20-dB suppression level. The mode conversion for both designs is lower than –30 dB. The signal integrity and the ESD protection function of proposed design are investigated by eye diagram measurement and system-level ESD simulation. The proposed PCB design provides a low-cost solution for the integration on the high-speed input/output interface of next generation.

Half-Mode Cavity-Based Planar Filtering Antenna With Controllable Transmission Zeroes

A two-pole half-mode substrate integrated waveguide (HMSIW) cavity-based filtering antenna is presented. The HMSIW cavity is used as a radiating resonator with a conventional substrate integrated waveguide (SIW) cavity functioning as a high- $Q$ resonator of the filter, leading to its compact size. The concept of source-load coupling is introduced for filtering antennas, which allows for the presence of two controllable transmission zeroes (TZs) in the frequency response of proposed design. This is accomplished by using electric coupling between two resonator cavities and a combination of microstrip/coaxial line to feed the antenna. The single-layer printed circuit board structure provides a broadside gain of 4.3 dBi at the operating frequency of 5.5 GHz. Gain curves are plotted at the broadside of the antenna, clearly showing a quasi-elliptic response and a 3-dB bandwidth of 2.6%.