Four-layer Printed Circuit Board Research Articles

A Novel Absorptive Common-Mode Filter for Cable Radiation Reduction

An absorptive common-mode filter (A-CMF) embedded in a four-layer printed circuit board is proposed. Unlike traditional CMFs, for the A-CMF, common-mode (CM) noise is absorbed through the surface mount resistor, so the transmitted and reflected CM noises can be suppressed simultaneously. The proposed A-CMF is synthesized and implemented based on the corresponding equivalent circuit model. To achieve a high-efficiency CM absorption at the desired frequency, through the analytical design equations, the values of the model elements are calculated and are all realizable. In this paper, at the operating frequency of 2.4 GHz, the 15-dB suppression level and 96% absorption efficiency are measured, while the size of the A-CMF is merely $8.65 \times 2.5$ mm2. Lastly, we designed two in situ experiments for fully demonstrating the suppression performances of CM-induced radiated noise. The measured results, within the operating frequency band of the A-CMF, show the receiving noise of an antenna nearby can be effectively reduced.

A Simple Miniature Ultrawideband Magnetic Field Probe Design for Magnetic Near-Field Measurements

A simple miniature magnetic-field probe for near-field measurements in 9-kHz–20-GHz bandwidth, which is applied to high-speed circuits, has been proposed and manufactured. The magnetic-field probe is built on a four-layer printed circuit board (PCB) using high-performance and low-loss Rogers material ( $\varepsilon _{r}= 3.48$ and tan $\delta = 0.0037$ ). Electric field coupling can be suppressed by PCB shielding structure of the magnetic-field probe. Coax-thru-hole via array technique is used to achieve impedance match. The resonance in working frequency band is suppressed through via fence, making $\vert S_{21}\vert $ rather smooth in the operation band. Experimental results show that the working frequency band is up to 9 kHz–20 GHz.

A copper electroplating formula for BVHs and THs filling at one process

Purpose The purpose of this paper is to introduce a new copper electroplating formula which is able to fill blind microvias (BVHs) and through holes (THs) at one process through a direct current (DC) plating method. Design/methodology/approach Test boards of printed circuit board (PCB) fragments with BVHs and THs for filling plating are designed. The filling plating is conducted in a DC plating device, and the filling processes and influence factors on filling effect of BVHs and THs are investigated. Dimple depths, surface copper thickness, thermal shock and thermal cycle test are applied to characterize filling effect and reliability. In addition, to overcome thickness, increase of copper on board surface during filling plating of BVHs and THs, a simple process called pattern plating, is put forwarded; a four-layered PCB with surface copper thickness less than 12 μm is successfully produced. Findings The filling plating with the new copper electroplating formula is potential to replace the conventional filling process of BVHs and THs of PCB and, most importantly, the problem of thickness increase of copper on board surface after filling process is overcome if a pattern plating process is applied. Research limitations/implications The dimple depth of BVHs and THs after filling plating is not small enough, though it meets the requirements, and the smallest diameter and largest depth of holes studied are 75 and 200 μm, respectively. Hence, the possibility for filling holes of much more small in diameter and large in depth with the plating formula should be further studied. Originality/value The paper introduces a new copper electroplating formula which achieves BVHs and THs filling at one process through a DC plating method. It overall reduces production processes and improved reliability of products resulting in production cost saving and production efficiency improvement.

Nanosecond Pulse Generator Based on an Unbalanced Blumlein-Type Multilayered Microstrip Transmission Line and Solid-State Switches

This paper combines an unbalanced Blumlein-type multilayered microstrip transmission line with solid-state switches to develop a high-voltage nanosecond pulse generator. This study was performed to emphasize the importance of a compact nanosecond pulse generator for biomedical applications. The unbalanced Blumlein-type transmission line reduces current flow through the solid-state switches. A multilayered microstrip transmission line is stacked onto the four-layered printed circuit board to minimize the system volume. Voltage wave propagation analysis is used to explain the principle of the system, which produced a rectangular pulse. The strategy to produce different pulse widths and the controlled timing of the related solid-state switches is interpreted according to this analysis, highlighting the approach needed to achieve a 50–100 ns pulsewidth. Also, the relevant principle of the variable load impedance of the unbalanced Blumlein-type multilayered microstrip transmission line system is also analyzed. To demonstrate the performance of the generator, a miniaturized system is established. Eventually, the nanosecond pulse generator produces a rectangular pulse on a resistor load of 50 $\Omega $ , with amplitude of 0–2 kV, pulsewidth of 50–100 ns, rise time of approximately 20 ns, and repetition frequency of 0 to several kilohertz. Also, when a 500 $\Omega $ resistor is used instead of a 50 $\Omega $ resistor, the output of the nanosecond pulse voltage is approximately two times that of the applied charging voltage.

Reactance components embedded in printed circuit boards

Purpose – This paper aims to report the investigations of capacitors and inductors embedded into printed circuit boards (PCBs) designed in various layouts. Design/methodology/approach – The research were focused on the components embedded into four-layer PCBs with different structures of the inner layers. Three special capacitive laminates for manufacturing of thin-film embedded capacitors and several types of coils in the form of a spiral, meander and solenoid are described. In addition, a part of the spiral-type coils was formed with an aperture in the center in which the magnetic core, made of soft magnetic composites’ material was placed to increase the coil inductance. Findings – Various constructions of embedded capacitors and coils were designed and manufactured. Capacitance and loss tangent of capacitors to determine the repeatability of the production process were determined. Capacitor’s long-term stability analysis was performed by exposing test samples to elevated temperatures (70, 100 or 130°C), realized with the aid of heating plate, for at least 160 h. The temperature characteristics for the capacitance and loss tangent from 15 to 100°C were determined. Also the induction of different designs and layouts coils was determined. Originality/value – The wide parameters’ characterization of capacitors and coils embedded into PCBs allow the analysis of their properties with regard to their practical application. The promising results of the realized measurements show that the capacitors and induction coils with studied structures can be widely used in the construction of embedded circuits into PCBs (e.g. filters, radio frequency identification systems and generators).

Systematic Design of Bandstop Power Distribution Network Using Resonant Vias

A systematic design method is proposed to achieve the optimal design of bandstop power delivery network (PDN) using resonant vias in a multilayered printed circuit board (PCB). With the proposed equivalent-circuit model, design equations, and design charts, the geometrical structure of a resonant via-type bandstop structure can be quickly designed according to the desired stopband bandwidth and isolation level. Wideband bandstop PDN designs using the resonant vias in standard four-layer PCB are fabricated and measured to demonstrate the effectiveness of proposed design method.

A Wearable Inertial Sensor Node for Body Motion Analysis

A wearable wireless inertial sensor node for body motion analysis is designed and implemented. A triaxial accelerometer, a biaxial gyroscope, and a yaw rate gyroscope are employed to sense the accelerations and angular rates of the object attached. These three ICs, a wireless mote, the power circuit, and a modified printed inverted-F antenna are integrated on a four-layer printed circuit board. To achieve the compact size for comfortable wearing, the printed antenna is deliberately designed as small as possible, while maintaining a reasonable antenna performance. The proposed inertial sensor node is also easily adaptable to applications with different power requirements because of the consideration of the periodic and moving-event wakeup in the software design. The static characteristics and Allan deviations of the implemented node are measured and analyzed. The false alarm rate of a moving detection based on Bayes rule is presented and a threshold is suggested. Finally, the raw data of several body motions are measured and those behaviors are observed apparently. The proposed inertial sensor node is compact and easily wearable; hence, it is feasible to be applied to the body motion analysis.

High-Speed (MHz) Series Resonant Converter (SRC) Using Multilayered Coreless Printed Circuit Board (PCB) Step-Down Power Transformer

In this paper, design and analysis of an isolated low-profile, series resonant converter (SRC) using multilayered coreless printed circuit board (PCB) power transformer was presented. For obtaining the stringent height switch mode power supplies, a multilayered coreless PCB power transformer of approximately 4:1 turn's ratio was designed in a four-layered PCB laminate that can be operated in megahertz switching frequency. The outermost radius of the transformer is 10 mm with achieved power density of 16 W/cm2. The energy efficiency of the power transformer is found to be in the range of 87-96% with the output power level of 0.1-50 W operated at a frequency of 2.6 MHz. This designed step-down transformer was utilized in the SRC and evaluated. The supply voltage of the converter is varied from 60-120 VDC with a nominal input voltage of 90 V and has been tested up to the power level of 34.5 W. The energy efficiency of the converter under zero-voltage switching condition is found to be in the range of 80-86.5% with the switching frequency range of 2.4-2.75 MHz. By using a constant off-time frequency modulation technique, the converter was regulated to 20 VDC for different load conditions. Thermal profile with converter loss at nominal voltage is presented.

A Multitransducer Microsystem for Insect Monitoring and Control

This paper reports the development and in-vivo testing of a compact multitransducer microsystem intended for neuroethology experiments, including studies of gait dynamics in free-running insects. The system incorporates a combination of custom and off-the-shelf components. Its suite of measurement devices comprises leg-mounted strain gauges, electromyogram (EMG) and extracellular electrodes for the central nervous system, and a two-axis accelerometer. For signal conditioning and selection, the microsystem implements off-the-shelf electronics in a custom chip-on-board configuration. The microsystem measures 16 mm x 19 mm, supports 40 components and 56 I/O leads, and is assembled on a four-layer printed-circuit board. The entire system occupies only 0.65 cm3 and weighs less than 5 g. It has been successfully used to monitor leg-strain and EMG signals on walking cockroaches and for stimulation in the insect central nervous and muscular systems.

Electrochemical migration characteristics of eutectic SnPb solder alloy in printed circuit board

The smaller size and higher integration of electronic components result in smaller gaps between metal conducting layers in an electronic package and printed circuit board (PCB). Under high temperature and humidity, electronic components respond to applied voltages by electrochemical ionization of metal and the formation of a filament, which leads to short-circuit failure of an electronic component, which is termed electrochemical migration (ECM). In this study, a four-layered PCB with SnPb electroplated through-hole-via was used to determine the ECM characteristics of a eutectic SnPb (63Sn–37Pb, weight percent) solder at a temperature of 85 °C, a relative humidity of 85%, and DC bias voltages between 75 and 100 V. Additionally, polarization tests for the solder materials were carried out to determine ECM characteristics. Pb was found to be more susceptible to polarization than Sn, which matched the composition distribution of the conductive anodic filament on the PCB surface.