Gbit/s transmission via two-photon-absorption-inscribed optical waveguides on printed circuit boards

Optical waveguides were inscribed into a 300 mm-thick polymer layer applied onto standard printed circuit boards via two-photon-absorption. VCSELs and photodiodes embedded in this layer of ORMOCERw complemented optical interconnects for multi-Gbit/s data transmission at a wavelength of 850 nm.     

MT-compatible laser-ablated interconnections for optical printed circuit boards

Integration of optical interconnections on a printed circuit board (PCB) is very challenging, since compatibility should be maintained with standard PCB manufacturing technology. This paper describes the use of laser ablation, a technique already used in PCB manufacturing for drilling microvias, as a suitable technique for the fabrication of multimode polymer waveguides, micromirrors, alignment features, and microlenses. A frequency-tripled Nd-YAG laser and a KrF excimer laser are used, both mounted on the same stage, resulting in very high alignment accuracies. This paper demonstrates a parallel optical link over approximately 5-cm-long PCB integrated waveguides, fully connected using a standard MT-based connector. This proves that laser ablation can be a key technology in optical board manufacturing to reach the stringent coupling tolerances.     

Estimating the power bus impedance of printed circuit boards with embedded capacitance

Embedded capacitance is an alternative to discrete decoupling capacitors and is achieved by enhancing the natural capacitance between closely spaced power and return planes. This paper employs a simple cavity model to investigate the features affecting the power bus impedance of printed circuit boards with embedded capacitance.     

Design and fabrication of waveguide-based chip-to-chip optical interconnection network on printed circuit boards

A waveguide-based chip-to-chip optical interconnection network on printed circuit board (PCB) was designed and fabricated, and experiments confirmed that the data rate in each channel could reach above 3.125 Gbit/s and the bit error rate (BER) could be up to 1.27×10-18, which would be a good solution to solve the communication bottlenecks between high-speed very large scale integration chips. Besides, the whole design and fabrication of optical interconnection network on printed circuit board has the advantages of high reliable, low cost and ease of manufacture.     

Power bus decoupling on multilayer printed circuit boards

Guidelines for the selection and placement of decoupling capacitors that work well for one-sided or two-sided printed circuit boards are not appropriate for multilayer boards with power and ground planes. Boards without internal planes take advantage of the power bus inductance to help decouple components at the higher frequencies. An effective decoupling strategy for multilayer boards must account for the low inductance and relatively high capacitance of the power bus     

A simple and effective model for electromagnetic bandgap structures embedded in printed circuit boards

Using a transmission-line model and considering a simple lumped-element substitute for the patch-via structure, a first-order, but detailed, quantitative and qualitative analysis of the filtering properties of a metallo-dielectric electromagnetic bandgap structure embedded in a printed circuit board is presented. This model is able to describe the resonant properties of the structure as well as its pass-band and stop-band regions.     

An accurate experimental method for characterizing transmission lines embedded in multilayer printed circuit boards

We have developed an accurate method for measuring the complex propagation constant and characteristic impedance of transmission lines embedded in multilayer printed circuit boards. It is based on mathematical error-removal schemes using two different length transmission lines and an advanced via-hole structure that minimizes coupling. Consequently, associated errors, due to discontinuities and interference can be effectively eliminated, and the frequency dependencies of the transmission line parameters can be clarified in wide frequency bandwidths. We verified the validity of this method in frequency ranges up to at least 18 GHz, by comparing the determined values with the theory derived from transverse electromagnetic (TEM) approximations.     

RF MEMS switches fabricated on microwave-laminate printed circuit boards

A novel fabrication process has been developed for directly constructing radio frequency microelectrical mechanical systems (RF MEMS) capacitive switches on microwave-laminate printed circuit boards (PCBs). The integrated process uses metal wet etching to form the metal lines for coplanar waveguides, compressive molding planarization (COMP) to planarize uneven surface heights for switch membrane formation, and high-density, inductively coupled plasma chemical vapor deposition (HDICP-CVD) for low-temperature silicon nitride deposition. This technology promises the potential of further monolithic integration with antennas on the same PCBs to form reconfigurable antennas without the concerns of mismatching among components.     

浅谈印制电路板信号损耗测试技术

在印制电路板设计、生产等过程中,传输线的信号损耗是板材应用性能的重要参数。信号损耗测试是印制电路板的信号完整性的重要表征手段之一。本文介绍了目前业界使用的几种PCB传输线信号损耗测量方法的原理和相关应用,并分析了其优势和限制。     

Preliminary assessment of the stability of thin- and polymer thick-film resistors embedded into printed wiring boards

Embedding passive components into multilayer printed wiring boards (PWBs) meet electronic device requirements concerning the necessity of saving the surface board area for active elements, reducing board’s size, improving device functionality and safety as well as overall product cost reduction. Since embedded components cannot be replaced after the board is completed, a long term stability and reliability are the important concerns for manufactures.This paper presents the results of examinations of embedded thin-film NiP resistors and polymer thick-film resistors during their continuous operation and the influence of temperature on the resistance values after the simulation of a lead-free soldering process and after the temperature cycling test (?40 ?C/+85 ?C).     

印制电路板内埋薄膜电阻和聚合厚膜电阻的可靠性初步评估

多层印制板内埋无源元件,可以节省有源元件安装面积,减小印制板尺寸,提高设备功能、提升安全性,并降低制造成本。由于制作完成后内埋式无源元件不可替换,元件是否拥有长期稳定性和可靠性是制造商最关心的方面。文章给出了内埋NiP薄膜电阻和聚合厚膜电阻持续作业的可靠性测试结果,讨论了无铅焊接模拟和温度循环测试（一40℃～＋85℃）的温度对阻值的影响。     

废旧印制电路板资源化处理现状

在大力倡导建设资源节约型和环境友好型社会的今天,加大对废旧印刷电路板的资源化研究,有着特别重大的意义。通过对废旧PCB的组成成分和废旧PCB中金属的含量分析,指出废旧PCB具有很大的可再生利用价值。着重综述了废旧PCB资源化的常规用法,主要包括热处理法、化学处理法、和物理机械处理法,并对这些方法做了的分析归纳。通过对各种方法的综述可以看出采用物理机械方法回收废旧电路板应该是今后的发展方向。     

Micromechanical analysis of copper trace in printed circuit boards

Printed circuit boards (PCB) are designed and manufactured with a variety of polyamide materials such as solder mask, metallic material such as copper trace, composite materials such as prepreg and core material. Polyamide materials such as solder mask and composite materials such as prepreg play important factor on the total deformation of laminate package due to the large coefficient of thermal expansion (CTE). On the other hand, the patterning of the copper layers also exerts important influence to the thermal mechanical behavior of the substrate due to the consistent large Young’s modulus of copper at both room temperature and reflow temperature compared with the small Young’s modulus of polyamide materials. Some approximate methods based on rule of mixtures have been used for estimating material properties in layers of copper mixed with interlayer dielectric material, but few techniques include the effect of copper trace pattern. The detailed comparison of different approximate methods has been done in this paper and a modified homogenization method has been proposed to include the effect of copper trace pattern. A series of three point bending test are performed with the comparison of numerical prediction using the proposed homogenization method and the detailed copper trace pattern respectively. Finally, a micromechanical analysis is done for the copper trace crack problem in package-on-package (PoP).     

Layer assignment for printed circuit boards and integrated circuits

The layer assignment problem arises in printed circuit board (PCB) and integrated circuit (IC) design. It involves the assignment of interconnect wiring to various planes of a PCB or to various layers of interconnect wires in an IC. This paper reviews basic techniques for layer assignment in both PCBs and ICs. Two types of layer assignment are considered: (1) constrained layer assignment in which routing of interconnections is given and the objective is to assign wires to specific layers, and (2) unconstrained, or topological, layer assignment, in which both the physical routing of interconnections and assignment of the wires to layers is sought. Various objective functions, such as via minimization and minimization of signal delays through interconnect lines are discussed     

Investigation of fundamental EMI source mechanisms drivingcommon-mode radiation from printed circuit boards with attached cables

Fundamental EMI source mechanisms leading to common-mode radiation from printed circuit boards with attached cables are presented in this paper. Two primary EMI source mechanisms have been identified: one associated with a differential-mode voltage and another associated with a differential-mode current, both of which result in a common-mode current on an attached cable. These mechanisms can he used to relate printed circuit layout geometries to EMI sources. The two mechanisms are demonstrated through numerical and experimental results, and an example from a production printed-circuit design is presented     

On the external inductive coupling of differential signalling on printed circuit boards

A study of the common-mode radiation behavior of differential signalling is presented, considering small current imbalances, which may originate from differential driver phase skew and circuit asymmetries. Two configurations are investigated, a solid ground plane and a ground plane with an open slit as an example of a ground-plane discontinuity. The external coupling voltage responsible for common-mode radiation is quantified through coupling inductances, for which closed-form expressions are derived and numerically validated. It is found that common-mode electromagnetic interference from differential signalling may become comparable to conventional single trace routing when traces are placed near the edge of the ground plane. For traces routed across a ground-plane discontinuity, differential signalling is only an effective means for reducing radiation when signal imbalance can be kept small.     

Power bus isolation using power islands in printed circuit boards

Power islands are often employed in printed circuit board (PCB) designs to alleviate the problem of power bus noise coupling between circuits. Good isolation can be obtained over a wide frequency band due to the large series impedance provided by the gap between the power islands. However, power bus resonances may degrade the isolation at high frequencies. The amount of isolation also depends on the type of connection between power islands and the components on the board. This paper experimentally investigates the effectiveness of several power island structures up to 3.0 GHz     

印制电路板高频介电常数测试技术现状分析

在印制电路板的设计、生产等过程中,板材的介电常数和介质损耗角正切都是影响板材应用性能的重要参数,因此,介电常数的测量准确性十分重要。本文介绍了目前使用的几种高频介电常数测量方法的原理、标准和相关产品,并分析了其优势和不足,以及测量技术的发展趋势。     

Numerical analysis of three-parallel embedded optical waveguides

Three parallel embedded dielectric waveguides are investigated numerically. The mode-matching method that matches the boundary conditions in the sense of least squares is applied to this problem, using the hybrid-modal representation. Precise numerical results for the dispersion relations and field distributions are presented for the lowest three modes near the cutoff. The frequency range in which only the three modes can propagate and the differences in their propagation constants are discussed at length, in order to highlight the available frequency range and the coupling length of the configuration with respect to its use as a directional coupler