PCB Technology Research Articles

Fabrication and testing of a 3D double-stack RPC with 30 gas gaps for detection of high energy gammas

Multigap Resistive Plate Chambers (MRPCs) are cost-effective detectors with a high-performance. They are easy to build and offer the possibility to cover large areas. They provide excellent time resolution and potentially good spatial resolution. In this context, a 3D RPC with 15 double-stack layers (30 gas gaps) free of parallax error is fabricated. The designed RPC has a 2D pixelated readout and the induced charge on the ground electrodes, gives the position in the third dimension. The simulation results show that in the X–Y plane the Full Width Half Maximum (FWHM) resolution is around 70 μm for 511 keV gammas, while for the Z-axis, which is perpendicular to the detector plane, a spatial resolution of around 560 μm can be achieved. The fill factor of the proposed detector with a pitch of 6.25 mm for SNR of 17 is around 0.13%, and the maximum achievable fill factor for the same setup and SNR of 42.5 is around 23%. The measured spatial resolution of the detector for a collimated Cs-137 point source is in good agreement with the simulation results. For an isotropic 511 keV gamma source at 0.95 cm distance of RPC detector, the experimental detection efficiency of constructed RPC at 1900V applied voltage is around 2.1%, which with a relative error of 7% is in good agreement with the simulation result obtained by GEANT4 (2.25%). With the same detector, at larger distances of the gamma source from the detector (clinical PET camera) a detection efficiency of around 5.09% is achievable. For small animal PET (100 mm radius) with 18F point source, the spatial resolution (Γ) of a PET system composed by 3D MRPC detectors with 2.25∗2.25 mm2 and 1∗1 mm2 pixel sizes, fabricated by commercial PCB technology (pitch = 6.25 mm) and Microlithography technology (pitch = 1.25 mm), would be 1.64 mm and 0.91 mm, respectively.

Wideband dual-polarized high-efficiency transmitarray using isolated metal elements

A wideband dual-polarized high-efficiency transmitarray antenna utilizing the isolated metal elements is proposed. First, a dual-polarized isolated metal element supported by a substrate frame is introduced. Each array element is isolated from adjacent elements by gaps. To realize the element, a substrate frame is used to completely fill the gaps and support the elements. As a result, the limitation of metal connections is overcome, and the transmitarray bandwidth is significantly enhanced. Based on equivalent circuit of the element, its wideband operating mechanism is revealed. Then, to reduce the manufacturing difficulties and costs while maintaining electrical performance, PCB technology is applied to the transmitarray fabrication, integrating the elements and the substrate frame. Finally, a wideband dual-polarized substrate-based metal transmitarray is designed, fabricated and measured. The measured results of the prototype indicate that its gain at the center frequency 10.2 GHz is 26.9 dBi, its 1-dB gain bandwidth is 23.4%, its efficiency is 56.1% and its lowest efficiency across the 1-dB gain bandwidth is 38% at 12.4 GHz. To the best of our knowledge, this is the first time a wideband two-layer substrate-based metal transmitarray has been proposed and implemented.

A stable high-gain cavity-stacked antenna array with compact high-order mode fed for W-band applications

This paper presents a W-band stable high gain 2 × 2 cavity-backed slot antenna array fed by compact high-order mode substrate-integrated cavity (SIC) with substrate-integrated waveguide (SIW) technology. The antenna element incorporates a 2 × 2 subarray of cross-shaped slots, excited by a high-order mode (TE220) SIC, ensuring uniform amplitude and balanced phase to achieve stable high-gain and high efficiency. Moreover, an additional SIW cavity is stacked above the 2 × 2 cross-shaped slots, incorporating a rectangular slot etched on the surface of the SIW cavity for radiation to further enhance the gain. This novel architecture yields a gain enhancement of 2.6 dBi compared to the traditional unstacked SIW cavity antenna. A prototype antenna array, consisting of 2 × 2 radiation elements and a low-loss 1-to-4 SIW power divider integrated with waveguide (WG) to SIW transition, is designed and fabricated in standard PCB technology. The measured results exhibit a −10 dB impedance bandwidth range from 91 to 97 GHz, a peak gain of 18.5 dBi, and a peak aperture efficiency of up to 78 %.

Design of a UWB patch antenna and performance evaluation in detecting brain tumors

In this study, a patch antenna is designed for easy fabrication and effective operation across a wide frequency range, making it particularly valuable for detecting brain tumors within a human head phantom using the monostatic technique. The study presents the proposed antenna's modeling in four stages, analyzing all essential parameters where a substrate material consisting of FR 4 is used. The antenna has a patch area of 0.27 λ × 0.21 λ and operates at 7.5 (free space), 7.48, and 7.47 GHz with a wide bandwidth of 3.188 GHz (free space), whereas in measurement, it operates in free space at 6.79 GHz with a bandwidth of 3.24 GHz, which is also categorized as an ultra-wide band. A comparative analysis is carried out between the proposed patch antenna and previous studies utilizing FR4 and similar substrate materials to enhance understanding. In this research, the analysis includes a human head phantom model, assessing key performance criteria such as SAR, return loss, and VSWR. The time-dependent analysis provides in this study insights into the dynamic behavior of the system in detecting brain tumor. The proposed antenna has been evaluated and yielded a maximum specific absorption rate (SAR) of 0.420985 W/kg for 1 gram of tissue in the head phantom. The performance of the patch antenna is evaluated using CST software, while the fabricated PCB antenna is tested in real-world conditions to ensure dependable operation in practical applications. The main challenge addressed in this work is achieving accurate brain tumor detection within a human head phantom model in a CST environment and using a UWB patch antenna fabricated via PCB technology.

Materials and manufacturing technology for high reliability rigid-flex multilayer PCB for space 3D-electronics packaging

Rigid-flex Multilayer PCB Technology enables the elimination of several connectors and bulky harness for interconnecting functional electronic systems. This minimizes packaging complexity and reduces performance degradation at high frequencies with an added advantage of reduced weight and volume in high-reliability space electronic packages. Here, only thermo-mechanically stable adhesiveless all polyimide flexible laminate cores and no-flow glass-polyimide prepregs are employed. To overcome the manufacturing issues like registration, coverlay protrusion into the rigid portions, and residual copper deposition at the intersections of flexible and rigid portions; a novel manufacturing process technology is proposed here. The technology has been successfully devised after choosing the most appropriate flexible, rigid, and low-flow prepreg materials. Herein, for the realization of rigid-flex multilayer PCB technology with 2-layers of flex and 8-layers of rigid to meet the functional requirements of the board is presented. The critical registration issues associated with the dissimilar rigid and flexible substrates are successfully addressed to achieve best-fit registration and obtain minimum annular rings of 50 μm in all the inner layers for high reliability. Experimental results manifest that incorporating rigid-flex multilayer PCB technology dramatically reduces weight (>30%) and volume (∼40%) to high-reliability space electronics 3D packaging for static and dynamic applications.

Theory vs. Reality: Using Printed Circuit Board Technology for Grounded Coplanar Waveguide at Millimeter-Wave Frequencies: Understanding PCB Technology for Millimeter-Wave Applications

Theory vs. Reality: Using Printed Circuit Board Technology for Grounded Coplanar Waveguide at Millimeter-Wave Frequencies: Understanding PCB Technology for Millimeter-Wave Applications

Low-Profile UWB Millimeter-Wave Antenna Array Under Triple Resonant Modes Based on PCB Technology

Low-Profile UWB Millimeter-Wave Antenna Array Under Triple Resonant Modes Based on PCB Technology

Design and validation of scalable reconfigurable intelligent surfaces

In this paper, we share our experience in designing, prototyping, and empirically characterizing RF Switch-based Reconfigurable Intelligent Surfaces (RIS). Our RIS design consists of arrays of patch antennas, delay lines, and programmable radio-frequency (RF) switches, enabling 3D beamforming passively, without active RF components. Our design introduces two key innovations: (i) a modular structure that provides scalability for sustainable deployments, and (ii) the support for 3-bit phase shifters, enabling high-spatial resolution codebooks. We realized this design through PCB technology and affordable electronic components, then rigorously validated our prototype in a controlled setting. With this paper, we make a comprehensive characterization of our RIS publicly available via a large dataset, to promote further empirical-driven research on this topic. Finally, we present a cost analysis of our design, which underscores the importance of sustainable practices in shaping the future of wireless technologies.

Composite Right/Left-Handed Leaky-Wave Antenna with Electrical Beam Scanning Using Thin-Film Ferroelectric Capacitors

This article presents a wide-angle-scanning leaky-wave antenna (LWA) based on a composite right/left-handed (CRLH) transmission line. In contrast to traditional semiconductor elements, thin-film ferroelectric capacitors were implemented in the CRLH unit cells to enable electric beam scanning. The proposed CRLH LWA has a single-layer design without metalized vias and is compatible with PCB and thin-film technologies. To fabricate the CRLH LWA prototype, dielectric material substrates and thin-film ferroelectric capacitors were manufactured, and their characteristics were investigated. Double-sided metalized fluoroplast-4 reinforced with fiberglass with a permittivity of 2.5 was used as a substrate for CRLH LWA prototyping. A solid solution of barium strontium titanate (BaxSr1−xTiO3) with a composition of x=0.3 was used as a ferroelectric material in electrically tunable capacitors. The characteristics of the manufactured ferroelectric thin-film capacitors were measured at a frequency of 1 GHz using the resonance method. The capacitors have a tunability of about two and a quality factor of about 50. The antenna prototype consists of ten units with a total length of 1.25 wavelengths at the operating frequency of close to 2.4 GHz. The experimental results demonstrate that the main beam can be shifted within the range of −40 to 16 degrees and has a gain of up to 3.2 dB. The simple design, low cost, and excellent wide-angle scanning make the proposed CRLH LWA viable in wireless communication systems.

A reproducible extrusion printing process with highly viscous nanoparticle inks

Abstract Printing of functional materials such as nanoparticle inks is a class of additive fabrication techniques complementary to standard subtractive electronics fabrication techniques such as pcb technology on pcb level or silicon based microelectronics on integrated circuit level. To date the majority of digital printing processes for (micro)electronics is inkjet based. Moreover aerosol jet based printing also establishes itself for printing on non-planar substrates and for materials with higher viscosities. A material deposition technique available since decades and mainly used for dispensing of adhesives and sealing materials is fluid-filament printing. It allows to cover a wide range of materials and viscosities and thus, also holds potential for additive manufacturing of electronics. In this paper we systematically study the influences on fluid filament printing both theoretically taking into account ink and equipment tolerances and experimentally using mainly standard dispensing equipment and two commercial screen printing inks. At the end of the paper we derive recommendations for reproducible printing of conductive lines and pads and give an outlook to printing 2.5D structures.

High-Gain Tapered Long Slot Array for Satcom Applications in PCB Technology With Folded Corporate Feed Network

High-Gain Tapered Long Slot Array for Satcom Applications in PCB Technology With Folded Corporate Feed Network

The Experiments and Stability Analysis of Hypersonic Boundary Layer Transition on a Flat Plate

Experimental and linear stability theory (LST) investigation of boundary layer transition on a flat plate was conducted with a flow of Mach number 5. The temperature distributions and second-mode disturbances on the flat plate surface at different unit Reynolds number (Reunit) values were captured by infrared thermography and PCB technology, respectively, which revealed the transition location of the flat-plate boundary layer. The PCB sensors successfully captured the second-mode disturbances within the boundary layer initially at a frequency of about 100 kHz, with a gradually expanding frequency range as the distance travelled downstream increased. The evolution characteristics of the second-mode instabilities were also investigated by LST and obtained for the second mode, ranging from 100 to 250 kHz. The amplitude amplification factor (N-factor) of the second-mode instabilities was calculated by the eN method. The N-factor of the transition location in the wind tunnel experiment predicted by LST is about 0.98 and 1.25 for Reunit = 6.38 × 106 and 8.20 × 106, respectively.

Air-filled SIW technology for mass-manufacturable and energy-efficient terahertz systems

To accommodate the ever-growing data requirements in densely populated areas and address the need for high-resolution sensing in diverse next-generation applications, there is a noticeable trend towards utilizing large unallocated frequency bands above 100 GHz. To overcome the harsh propagation conditions, large-scale antenna arrays are crucial and urge the need for cost-effective, mass-manufacturable technologies. A dedicated Any-Layer High Density Interconnect PCB technology for highly efficient wireless D-band (110–170 GHz) systems is proposed. Specifically, the adapted stack accommodates broadband air-filled substrate-integrated-waveguide components for efficient long-range signal distribution and low-loss passives. The viability of the suggested technology platform is demonstrated by designing, fabricating and measuring several essential low-loss air-filled substrate-integrated-waveguide components, such as a dual rectangular filter, with a minimal insertion loss of 0.87 dB and 10 dB-matching within the (132.8–139.2 GHz) frequency band, and an air-filled waveguide with a routing loss of only 0.08 dB/mm and a flat amplitude variation within 0.01 dB/mm over the (115–155 GHz) frequency range. A broadband transition towards stripline, with a limited loss of 1.1 dB, is described to interface these waveguides with compactly integrated chips. A tolerance analysis is included as well as a comparison to the state of the art.

A Highly Sensitive 3D Resonator Sensor for Fluid Measurement.

Planar sub-wavelength resonators have been used for sensing applications, but different types of resonators have different advantages and disadvantages. The split ring resonator (SRR) has a smaller sensing region and is suitable for microfluidic applications, but the sensitivity can be limited. Meanwhile, the complementary electric-LC resonator (CELCR) has a larger sensing region and higher sensitivity, but the topology cannot be easily designed to reduce the sensing region. In this work, we propose a new design that combines the advantages of both SRR and CELCR by incorporating metallic bars in a trapezoid-shaped resonator (TSR). The trapezoid shape allows for the sensing region to be reduced, while the metallic bars enhance the electric field in the sensing region, resulting in higher sensitivity. Numerical simulations were used to design and evaluate the sensor. For validation, the sensor was fabricated using PCB technology with aluminum bars and tested on dielectric fluids. The results showed that the proposed sensor provides appreciably enhanced sensitivity in comparison to earlier sensors.

A Novel Eddy Current Sensor for Displacement Measurement With High Accuracy and Long Range

To enlarge the measurement range of traditional eddy current displacement sensors, a novel eddy current linear sensor for displacement measurement with high accuracy and long range is proposed in this paper. The sensor consists of a stationary component with metal reflection conductors and a movable component with spiral coils. The metal reflection conductors below the movable component will generate an eddy current and radiate an eddy current magnetic field after the high-frequency alternating excitation signal is applied to field spiral coils. The inductive electromotive forces (EMFs) will be generated in inductive spiral coils. The measurement of displacement relies on the inductive EMFs variation of inductive spiral coils caused by the change of coupling areas between the spiral coils and the metal reflection conductors. The absolute positioning is realized by the combination of a coarse measurement channel and a fine measurement channel. The structure and measurement principle are described in detail. A sensor prototype is fabricated by PCB technology, and the experiments are carried out. Based on the experimental results, some error sources are analyzed and the sensor is optimized. The experimental results show that the sensor can achieve absolute positioning, and the worst-case error is 6.75 μm within the measurement range of 500 mm.

Fast and Accurate Analytical Thermal Modeling for Planar PCB Magnetic Components

The exploitation of PCB integrated magnetic components in the high power field brings new challenges due to the compactness of the design and the poor thermal performance of components using standard PCB technology. In this work, a thermal modelling approach is proposed which is suitable for optimization based design of planar PCB magnetic components. The targets are high accuracy, low computation time and easy implementation. The results show an accuracy comparable to Finite Element simulations, with average absolute error of 1.3 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{\circ }$</tex-math></inline-formula> C respect to measurement, while the computation time is 13 times shorter than simplified Finite Element simulations. The equations are purely analytical, i.e. no measurements or simulations are needed to obtain the involved parameters. The structure of the model enables easy and fast generation of PCB geometries, with the possibility to make a parametric sweep of any variable. The model has been verified with Finite Element simulations and experimental measurements for a wide range of operating conditions, including dc and ac excitation.

Wideband Circularly Polarized Millimeter-Wave DRA Array for Internet of Things

This work proposes a novel millimeter-wave wideband circularly polarized antenna array for Internet of Things (IoT) applications. The proposed design addresses the issues of having IoT sensors deployed in remote locations or over large geographical regions. Elliptically-shaped dielectric resonator antennas (DRAs) are used as array elements to improve radiation characteristics and achieve circular polarization over a wide impedance bandwidth around 28 GHz. Two different sequential-phase corporate feed networks are studied and compared to obtain wider impedance, 3-dB gain, and axial ratio (AR) bandwidths. Furthermore, a ridge gap waveguide technique based on the low-cost PCB technology is adopted to reduce the transmission losses in the considered sequential-phase feed networks. The proposed millimeter-wave antenna exhibits an impedance bandwidth of 35% (28.1-40 GHz) and 3-dB gain bandwidth of 19.3% (27.6-33.5 GHz). The achieved 3-dB AR bandwidth is 22.6% (27.5-34.5 GHz). The proposed antenna was fabricated and measured, and good agreement between measured and simulated results was obtained. The reported results show that the suggested wideband circularly polarized millimeter-wave antenna has a lot of promise in preventing polarization mismatch losses between IoT devices and satellites caused by their varying orientations.

Wideband High-Efficiency Circularly Polarized Transmitarray With Linearly Polarized Feed

By using the low loss element design method, a wideband high-efficiency transmitarray antenna with the linear-to-circular-polarization transformation is presented. The element is composed of a linearly polarized U-slot patch antenna and a circularly polarized shaped single-arm Archimedean spiral antenna, and has the advantages of low insertion loss and good incident angle stability over a wide frequency band. The 0.14-λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> -thick 1613-element transmitarray is fabricated by the standard PCB technology, and presents a measured peak gain of 31.8 dBi with the corresponding aperture efficiency of 60.2%. The measured 1-dB gain bandwidth is 15.2% from 18.25 GHz to 21.25 GHz. Simple structure, high performance and low complexity make it an attractive candidate for the low-cost high-gain circularly polarized antenna.

Development of a wireless passive capacitively coupled contactless conductivity detection (WPC4D) for fluidic flow detection utilizing 3D printing and PCB technologies

A modified capacitive-coupled contactless conductivity sensor is proposed and developed for microfluidic flow detection based on the passive wireless inductor-capacitor (LC) technique. The device utilizes rapid prototyping including PolyJet 3D printing and PCB technologies to fabricate the microchannel and the readout inductor through which the conductivity of the fluidic flow is analyzed and foreign objects identified. The system employs an LC resonance circuit to monitor the shift in frequency and the change in the reflection coefficient, thereby estimating the conductivity of the fluidic flow and the appearance of objects. The operating principles were characterized by numerical calculations. The performance was validated by experimental measurements. The results show that the higher the electrical conductivity (i.e. the higher concentration) of the NaCl solution passing through the sensing area, the lower the resonance frequency. The resonance frequency due to the passage of NaCl solution with concentrations of 0.1, 0.5, and 1 M were 225.24, 218.93, and 215.67 MHz, respectively. The influence of the distance between the inductors on the resonance frequency of different solution conductivities has also been studied. The sensor system has high potential in various biomedical and chemical applications, particularly in point-of-care applications where sensor chips can be easily incorporated.

A Planar Integrated Rectenna Array With 3-D-Spherical DC Coverage for Orientation-Tolerant Wireless-Power-Transfer-Enabled IoT Sensor Nodes

Multiple IoT sensor nodes with radio frequency (RF) power harvesting are deployed in random positions and orientations with respect to the power transmitter (Tx) generally installed on ceiling and side walls. The IoT sensor nodes with wireless power transfer (WPT) systems employing conventional rectenna designs with complex structures can provide only 2-D coverage, thus, free-positioning and orientation-insensitive WPT is unrealizable. Therefore, a novel, compact, planar-integrated rectenna-array providing 3-D-spherical coverage is proposed for the WPT system in two-layer PCB technology. The proposed design scheme harvests maximum RF power in both, azimuth and elevation planes, by encapsulating endfire and inherent tilted-beam bore-sight rectenna elements within a single sector. The radial integration of six such sectors coordinately achieves 3-D-spherical dc coverage, and the bore-sight 3 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times1$ </tex-math></inline-formula> patch antenna array (PA) functions as a dc low pass filter (dc-LPF) offering miniaturization and insertion loss reduction. The endfire and bore-sight rectenna components harvest 240 and 255 mV at 1280 and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1176~\Omega $ </tex-math></inline-formula> output loads with RF-dc conversion efficiency of 69.1% and 65.28% at 5.8 GHz, respectively. Further, the rectenna elements are integrated using a simple and easily realizable low-loss parallel dc combining circuit, making it suitable for IoT sensor nodes.