High Frequency Signal Transmission Research Articles

Epoxy composite films of superior dielectric properties promoted by active ester hardeners for applications in electronic packaging

Epoxy composites with ultralow dielectric dissipation factors (Df) are highly desired in advanced electronic packaging architectures to cater for high-frequency signal transmission. However, Df of epoxy systems traditionally cured by amine, anhydride or phenolic resin is too high due to the generated high-polarization groups like hydroxyl moieties. Using active esters as curing agents is an effective strategy to reduce polarization of cured epoxy by replacing hydroxyl moieties with ester groups. Herein, diallyl-based active ester hardeners (DAAE) are synthesized via one-step esterification reaction with a high yield of > 90 %. When DAAE is used to cure epoxy films containing SiO2 fillers, the cured epoxy composite films (DAAE-ECFs) demonstrate low dielectric constant (Dk, ∼3.0) and low Df (∼0.005) above 5 GHz at 25 ℃. Importantly, whether immersed in room-temperature water for 24 h or in boiling water for 1 h, DAAE-ECFs absorb < 0.6 wt% water with stable Dk and slightly increased Df (<0.0085). Moreover, DAAE-ECFs show excellent thermal stability (Td5% >365 ℃), dimensional stability (CTE of ∼ 30 ppm ℃-1 below 80 ℃), high storage modulus (∼10 GPa at 30 ℃). The appealing dielectric, thermal and mechanical properties imply that DAAE-ECFs could serve as promising candidates for electronic packaging materials in high-frequency signal transmission.

Research on characteristics of radio interference of MMC-HVDC lines

Abstract Previous research on radio interference in DC lines has focused on radio interference caused by corona discharge. But with the development of Modular Multilevel Converter Based High Voltage Direct Current (MMC-HVDC) systems, high frequency signals generated by fast switching of Insulate-Gate Bipolar Transistor (IGBT) are transmitted to Direct Current (DC) lines and radiate radio interference outward. On the one hand, the radio interference formula recommended by the dual-level DC transmission line recommended by International Special Committee on Radio Interference (CISPR) is calculated by the radio interference generated by the line corona discharge; On the other hand, by establishing a MMC-HVDC line model, analyse the high frequency signal transmission generated by the fast switching of IGBT in the Modular Multilevel Converter (MMC) to the radio interference generated by radiating outside the DC line. The results of the study show that the radio interference generated by high -frequency signals of IGBT fast switching will decrease with the length of the line. The radio interference value generated by corona discharge is 47.43 dB(μV/m), the radio interference generated by the high-frequency signal of IGBT fast switching is 40.83 dB(μV/m), which is too small than the radio interference of corona discharge.

Vertical Interconnections by Electroless Pd Atoms on Immersion Au Surface for Heterogeneous Integration

Electroless Pd atoms were employed to bond vertical interconnection for chip-stacking applications without pressure and at a temperature below 100 °C. Vertical interconnections were created by channeling an electroless Pd plating solution through microchannels, enabling the reduced Pd atoms to assemble naturally within the gaps between two opposing Cu pillars. Notably, the Pd deposition resulted in epitaxial growth along the orientation of the Cu pillar surface, suggesting improved electrical properties for future high-frequency applications. In this study, highly uniform electroless Pd-bonded Cu pillar joints were fabricated using a patterned microfluidic system. The required bonding time was significantly correlated with the plating temperature. Furthermore, the electroless Pd-bonded joints exhibit a robust strength of approximately 55 MPa. Pd exhibits greater skin depth than other plating materials, which helps reduce signal loss and latency during high-frequency signal transmission. This innovative approach offers promise as a potential candidate for future 5G applications requiring low bonding stress and minimal thermal budget.

Metallized liquid crystal polymer with low interfacial roughness and excellent adhesive strength based on semi-additive process for high-frequency signal transmission

Fifth-generation communication (5G) with the feature of high frequency puts forward harsh requirements on the roughness of the transmission lines due to the skin effect. Metallization liquid crystal polymer (LCP) with low interfacial roughness and high adhesive strength simultaneously poses a huge challenge for the modern electronics. Herein, based on semi-additive process, molecular grafting is reported to highly bridge smooth LCP substrate and thickened copper layer by chemical bonds. The process comprises the wettability of LCP surface tuned via oxygen plasma with negligible roughness changes. γ-aminopropyl triethoxysilane (APTES) plays a role in the integration of LCP substrate and metal layer. Followed by electroless plating, a thin nickel is planted on LCP as conductive seeds for electroplating copper. Compared with addition manufacturing, which directly coarsens the interface of circuits, semi-addition process just etches the edge of circuits. Through APTES grafting, 10 μm thick copper on LCP substrate reaches to the level of 5B according to the criteria of ASTM D3359, overcoming the trade-off between low interfacial roughness and high adhesive strength of existing techniques. Additionally, the interfacial strengthening mechanism of APTES grafting is carefully investigated. The proposed grafting-assisted semi-additive process is potentials for scalable fabrication of high-frequency electronics on various substrates.

High-frequency signal transmission in a coplanar waveguide structure with different surface finishes

Continuous pursuits for higher data rate, larger network capacity, low-latency communication, and better energy efficiency have motivated the development of the fifth generation (5 G) mobile communication technologies in recent years. Under a high-frequency transmission, the alternating electric current (AC) tends to distribute to the outer of a conductor due to the so-called “skin effect”; therefore, the surface coatings of Cu interconnect becomes an indispensable factor of the signal transmission characteristics. The focus of this study is to deeply probe into the effect of surface coatings on the high-frequency signal transmission (1–100 GHz) of Cu interconnects. We investigated six different surface finishes over a coplanar waveguide (CPW) transmission line structure, including immersion tin (ImSn), immersion silver (ImAg), immersion gold (IG), electroless palladium/immersion gold (EPIG), immersion gold/electroless palladium/immersion gold (IGEPIG), and ultrathin-Ni(P)-type ENEPIG. The high-frequency signal performance of the CPW transmission line was analyzed through the finite element analysis (FEA) method by using a 3D electromagnetic simulation software. Furthermore, experimental measurements were conducted by using a vector network analyzer (VNA) to characterize the signal loss arising from different surface finishes, so as to validate the numerical simulation results. The FEA and VNA results showed that a noticeable current redistribution might be induced by a high conductivity/permeability of surface coating(s), i.e., ImSn and ultrathin-Ni(P)-type ENEPIG, which significantly increases the signal insertion loss at high frequencies. Thus, an appropriate surface coating over Cu interconnects was necessary for enhancing the high-frequency signal transmission performance.

Research on Variable Parameter Drilling Method of Ti-CFRP-Ti Laminated Stacks Based on Real-Time Sensing of Drilling Axial Force.

Ti-CFRP-Ti laminated stacks have been widely used in aviation, aerospace, shipbuilding and other industries, owing to its excellent physical and electrochemical properties. However, chip blockages occur easily when drilling into Ti-CFRP-Ti laminated stacks, resulting in a rapid rise of drilling temperature and an increase of axial drilling force, which may lead to the intensification of tool wear and a decline of drilling quality. Cutting force signals can effectively reflect the drilling process and tool condition, however, the traditional plate dynamometer is typically difficult in realizing the follow-up online measurement. Therefore, an intelligent tool holder system for real-time sensing of the cutting force is developed and constructed in this paper, and the variable parameter drilling method of Ti-CFRP-Ti laminated stacks is studied on this basis. Firstly, an intelligent tool holder system with high flexibility and adaptability is designed; Secondly, a cutting force signal processing method based on compressed sensing (CS) theory is proposed to solve the problem of high-frequency signal transmission; Lastly, the drilling experiment of Ti-CFRP-Ti laminated stacks is carried out based on the intelligent tool holder system, and the drilling parameters are optimized using a compromise programming approach and analytic hierarchy process (AHP). The comparison of results show that the optimized drilling parameters can effectively reduce the hole wall surface roughness and improve the drilling efficiency while ensuring a small axial force.

Research on RF Voltage Measurement Method of Chip Pins

As the core device of electronic equipment, integrated circuit (IC) usually produces large high-frequency electromagnetic interference. In order to study the generation mechanism and suppression methods of such noise, accurate noise measurement and extraction must be carried out. At present, the measurement standard of chip level electromagnetic compatibility is not perfect, and the high-frequency characteristics of pin noise are difficult to be measured accurately. In order to achieve accurate chip pin RF voltage measurement, this paper designs a chip pin RF voltage measurement method, establishes the 3D model of the chip pin RF voltage measurement module, studies the effects of its wiring, via, substrate dielectric constant and other parameters on its high-frequency signal transmission performance, and then optimizes the module. Simulation and experimental results show that the optimization method effectively improves its high-frequency signal transmission characteristics. Finally, the RF voltage of the output pin of the active crystal oscillator is extracted by using the detection system designed in this paper.

Progress on Polymer Composites With Low Dielectric Constant and Low Dielectric Loss for High-Frequency Signal Transmission

The development of information transmission technology towards high-frequency microwaves and highly integrated and multi-functional electronic devices has been the mainstream direction of the current communication technology. During signal transmission, resistance-capacitance time delay, crosstalk, energy consumption increase and impedance mismatch restrict the high density and miniaturization of Printed circuit board (PCB). In order to achieve high fidelity and low delay characteristics of high-frequency signal transmission, the development of interlayer dielectric materials with low dielectric constant (Dk) and low dielectric loss factor (Df) has become the focus of researchers. This review introduces the dielectric loss mechanism of polymer composites and the resin matrix commonly used in several high-frequency copper-clad laminates, and mainly describes how to reduce the dielectric constant and dielectric loss of materials from the level of molecular structure design, as well as the effect of fillers on the dielectric properties of polymer substrates. As a kind of potential functional fillers for dielectric polymeric composites, the carbon nanofillers are used to tailor the dielectric properties of their composites via different dimensions and loadings, as well as their proper preparation methods. This review finally summarizes the interface bonding failure mechanism and a feasible idea to optimize the dielectric properties of polymer matrix composites is also proposed.

Investigation of organic additives to regulate growth and signal transmission loss of copper interconnection structure

<p indent=0mm>Signal integrity is severely limited by the copper roughness. Plating solution containing different organic additives could influence the roughness of electroplating copper growth. Molecular simulation and electrochemical tests were used to regulate the competitive adsorption behavior of organic additives on the copper surface and understand the possible mechanism on the difference of copper growth. The results show that the plating solution system containing bis-(sodium sulfopropyl)-disulfide (SPS), ethylene oxide-propylene oxide copolymer (EO/PO) and Janus Green B (JGB) can contribute to the copper growth with smooth surface, leading to insertion loss of <sc>−8.9 dB@20 GHz.</sc> Therefore, organic additives could be used to regulate the low-profile growth of copper interconnection structure and reduce transmission loss to effectively ensure the integrity of high-frequency signal transmission.

Spike Activity Regulates Vesicle Filling at a Glutamatergic Synapse.

Synaptic vesicles need to be recycled and refilled rapidly to maintain high-frequency synaptic transmission. However, little is known about the control of neurotransmitter transport into synaptic vesicles, which determines the contents of synaptic vesicles and the strength of synaptic transmission. Here, we report that Na+ substantially accumulated in the calyx of Held terminals of juvenile mice of either sex during high-frequency spiking. The activity-induced elevation of cytosolic Na+ activated vesicular Na+/H+ exchanger, facilitated glutamate loading into synaptic vesicles, and increased quantal size of asynchronous released vesicles but did not affect the vesicle pool size or release probability. Consequently, presynaptic Na+ increased the EPSCs and was required to maintain the reliable high-frequency signal transmission from the presynaptic calyces to the postsynaptic medial nucleus of the trapezoid body (MNTB) neurons. Blocking Na+/H+ exchange activity decreased the postsynaptic current and caused failures in postsynaptic firing. Therefore, during high-frequency synaptic transmission, when large amounts of glutamate are released, Na+ accumulated in the terminals, activated vesicular Na+/H+ exchanger, and regulated glutamate loading as a function of the level of vesicle release.SIGNIFICANCE STATEMENT Auditory information is encoded by action potentials (APs) phase-locked to sound frequency at high rates. A large number of synaptic vesicles are released during high-frequency synaptic transmission; accordingly, synaptic vesicles need to be recycled and refilled rapidly. We have recently found that a Na+/H+ exchanger expressed on synaptic vesicles promotes vesicle filling with glutamate. Here, we showed that when a large number of synaptic vesicles are released during high-frequency synaptic transmission, Na+ accumulates in axon terminals and facilitates glutamate uptake into synaptic vesicles. Na+ thus accelerates vesicle replenishment and sustains reliable synaptic transmission.

Research on High Frequency Signal Transmission Method of Transmission Line under Internet of Things Communication Environment

In order to better promote the safety and stability of transmission line signal transmission, a research on transmission line high frequency signal transmission method based on Internet of Things communication environment is proposed. Firstly, the noise interference in the transmission line signal transmission process is removed by combining the wavelet transform algorithm, and the original high-frequency signal is subjected to waveform constraint processing after denoising, so as to realize the safe transmission of the high-frequency signal of the electric line. Finally, the experiment proves that the transmission line high-frequency signal transmission method under the Internet of Things communication environment has higher safety and stability than the traditional method, which fully meets the research requirements.

All optical Millimeter-wave signal generation and transmission for radio over fiber (RoF) link

&lt;span&gt;Fiber-based wireless system has become a promising solution as a cost- effective communication and it offers high capacity network with millimeter- wave (mm-wave) signal transmission. The system significantly offers superior possible bandwidths for both fiber and free-space applications. Hence, with the increased capacity as well as wireless mobile network applications particularly at mm-wave signal, radio over fiber (RoF) technology is the utmost option. Nevertheless, when high frequency signal transmission is involved, power fading or dispersion effect limits the performance of RoF link. Therefore, this work proposed a RoF system by integrating remote optical local oscillator (LO) with frequency up-conversion at the base station (BS). All optical mm-wave signals are generated and transmitted for the RoF link. The effects of the changes of fiber loop length, optical power of the continuous wave (CW) optical laser carrier and responsivity value of the p-i-n photodiode (PD) mainly at 40 GHz are investigated and the power fading effects are discussed.&lt;/span&gt;

The Effect of Electrical Connector Degradation on High-Frequency Signal Transmission

Electrical connector failures may alter the signal that is being transmitted and is one of the major causes of low communication quality. As the connector degrades, the dc resistance and the impedance characteristics induced by the corrosion products should both be considered. In this paper, the effects of electrical connector degradation on its high-frequency behaviors were experimentally studied and theoretically analyzed. A series of experiments was conducted to test the internal impedance of connectors for different degradation levels using an impedance analyzer. It was found that when the connector initially degrades, it exhibits an inductive characteristic in the application frequency range. As its further degrades, the inductive characteristic will decrease, and as the degradation increases to a certain degree, the connector will exhibit a more capacitance-like impedance. An equivalent impedance model was developed to explain this phenomenon. Analyzing the degraded pin/receptacle pair and calculating the equivalent impedance parameters, it was found that both the resistance and capacitance induced by the corrosion were frequency +dependent. The nonlinear property and frequency-dependent impedance characteristics of the degraded connector may influence signal reflection and insertion loss and cause system malfunctions.

Incorporation of Tin on copper clad laminate to increase the interface adhesion for signal loss reduction of high-frequency PCB lamination

A novel method of improving the adhesion between copper and prepreg in high frequency PCB was proposed and studied in this work. This process which aimed to decrease the IEP (isoelectric point) of the copper to obtain higher adhesion, was achieved by depositing a thin tin layer with lower IEP on copper. It was characterized by scanning electron microscopy (SEM), 3D microscope, peel strength test, X-Ray thickness test, grazing incidence X-ray diffraction (GXRD), X-ray photoelectron spectroscopy (XPS), Agilent vector network analyzer (VNA), which confirmed its excellent adhesion performance and outstanding electrical properties in high-frequency signal transmission compared with traditional brown oxide method. Moreover, the mechanism of achieving high adhesion for this method was also investigated.

Simulation of a High-Frequency Link of Phase Comparison Protection of Transmission Lines for Optimization its Settings

The objective of this work is to determine the influence of high-frequency link (HFL) on functioning of phase comparison protection (PCP) through the usage of detailed models that take into account specific features of the PCP and processes in HFL. The article describes the case of the most common variant of the high frequency signal transmission by using a scheme ‘phase-to-ground’. To verify suggested solution the developed mathematical model of HFL has been studied. Presented simulation results confirm the effectiveness of the proposed approach for solving the problem.

High-frequency signal transmission through single-atom contacts of Au and Pt

Signal transmission through atom-sized contacts of Au and Pt has been studied at room temperature for frequencies from 9 kHz to 1 GHz and for conductances (1−10)G0 (G≡2e2/h is the quantum unit of conductance). We measured the frequency spectrum of S parameter S21=|S21|eiθ and found θ∼0 up to 1 GHz for all contacts irrespective of their conductance. Our observations directly prove that the atom-sized contacts of Au and Pt, including their single-atom contacts, behave as a pure resistance in the RF regime.

Impedance Matching Using the Smith Chart

Impedance matching is a basic requirement for high frequency signal transmission, but also a relatively complicated aspect in circuit design. In this article, from the perspective of impedance matching, structure principle and characteristics of Smith chart are introduced. On the basis of Smith chart software, its process of impedance matching is described with a simple example to show the advantages of convenient and fast calculation of Smith chart for impedance matching.

Power Line Carrier Communication Meter Concentrator Hardware Design

This paper analyzes the characteristics of a high-frequency signal transmission power lines ; focused on the spread spectrum communication technology in power line carrier communication ; -depth study of the spread spectrum modulation and demodulation techniques in communication technology-based , high-performance power line carrier dedicated MODEM chip SSC P300 internal works. Focuses on the design of the concentrator hardware systems.

Multiharmonic Generator for Large-Signal-Network-Analyzer Verification

Since S-parameters were first used to describe linear microwave circuits in the 1960s, circuit designers, software developers, and instrument manufacturers have gradually come to an agreement on this blackbox representation, resulting in significant advancements in modeling, simulation, and measurement. As a mathematical language of high-frequency signal transmission and scattering, S-parameter stands for a unified form of the linear characteristics of microwave networks in the frequency domain. Subsequently, the vector network analyzer (VNA) was invented as the principal instrument to measure S-parameters and characterize the linear behavior of devices and components, including small-signal active circuits.

Variable Multi-Channel High Frequency Signal Acquisition System

A flexible system to multi-channel high frequency signal acquisition and transmission was designed. The system took FPGA as the center control logic unit. It could realize real-time acquisition, conditioning, modulus conversion to multi-channel high frequency signal and sent the converted digital signal to the storage device through FIFO. The system could also realize the real-time monitoring, data unpacking and analysis to storaged data by using computer software. FPGA software design adopted VHDL language. The experiment results show that this data acquisition and transmission system is stable and accurate.