Conventional PCB Research Articles

Semi-lumped Balun Transformer using Coupled LC Resonators

This paper presents a semi-lumped balun transformer using conventional PCB process and its design theory and geometry for the maximally flat response and wide bandwidth using magnetically coupled LC resonators. The proposed balun is comprised of two pairs of coupled resonators which share one among three LC resonators. It provides an identical magnitude and phase difference of 180° between two balanced ports with DC isolation and an impedance transformation characteristic. Theoretical design and analysis were performed to optimize the inductance and capacitance values of proposed balun device for obtaining the wide bandwidth and maximally flat response in its pass-band. Three balun transformers with a center frequency of 500 MHz were demonstrated for proving the concept of design proposed. They were fabricated by using lumped chip capacitors and planar inductors embedded into a conventional 4-layered PCB substrate. They exhibited a maximum magnitude difference of 0.8 dB and phase difference within 2.4 degrees.

플라즈마 유기막과 OSP PCB 표면처리의 Sn-Ag-Cu 솔더 접합 특성 비교

본 연구에서는 친환경적이고, 보관수명이 1년 이상이며, 부식특성이 좋은 플라즈마 유기막 표면처리에 대한 솔더링 특성을 기존 표면처리법인 OSP와 비교하였다. 플라즈마 표면처리는 할로겐계 전구체를 사용하여 CVD 방법으로 증착하였고, 증착두께는 20 nm이었다. 본 연구에서 사용된 솔더 조성은 Sn-3.0 wt%Ag-0.5 wt%Cu이었다. 염수분무시험에서 플라즈마 표면처리 유기막은 OSP보다 우수한 부식 저항성을 나타내었다. 멀티리플로우 조건에서 플라즈마 표면처리는 OSP보다 우수한 솔더 퍼짐성을 나타내었다. 솔더링 후 단면 미세조직을 분석한 결과, 플라즈마 표면처리와 OSP시편 모두 유사한 금속간화합물층 두께 및 형상을 갖고 있었다. 플라즈마 표면처리와 OSP 모두 유사한 접합강도를 가지고 있었다. Plasma organic thin film for PCB surface finish is a potential replacement of the conventional PCB finishes because of environment-friendly process, high corrosion-resistance and long shelf life over 1 year. In this study, solder joint properties of the plasma organic surface finish were estimated and compared with OSP surface finish. The plasma surface finish was deposited by chemical vapor deposition from fluorine-based precursors. The thickness of the plasma organic coating was 20 nm. Sn-3.0Ag-0.5Cu (SAC305) solder was used as solder joint materials. From a salt spray test, the plasma organic coating had higher corrosion resistance than the OSP surface finish. The spreadability of SAC305 on plasma organic coating was higher than that on OSP surface finish. SEM and TEM micrographs showed that the interfacial microstructure of the plasma surface finish sample were similar to that of the OSP sample. Solder joint strength of the plasma finish sample was also similar to that of the OSP finished sample.

광 PCB 접속용 플러거블 렌즈의 설계 및 제작 연구

본 연구에서는 기존의 PCB의 한계를 극복할 수 있는 광 PCB에 대한 연구를 수행하였으며, 고효율 수동정렬을 위한 플러거블 렌즈구조를 제안하였다. 제안된 구조는 광 도파로 수동 정렬시 발생할 수 있는 렌즈와 도파로 간의 정렬 오차를 개선하고자 도파로와 렌즈를 합한 형태이다. 또한 탈착에 의해 손상되는 렌즈표면을 보호하기 위한 보호벽 형태를 지님으로써, 고효율의 수동정렬이 가능하게 하였다. 최적화 시뮬레이션을 통하여 구조를 설계하였고, 반복적 포토 리소그래피와 열적 리플로우 공정을 통하여 플러거블 렌즈 구조 제작을 위한 공정 연구를 수행하였다. 렌즈일체형 플러거블 접속구조의 광도파로를 PDMS복제공정으로 제작된 mold를 이용하여 임프린트 공정을 통해 제작하였다. 따라서 본 논문에서는 수동정렬이 가능한 광PCB접속용 플러거블 렌즈 구조의 제작이 가능함을 확인하였다. In this study, an optical PCB was proposed which can overcome the limitations of the conventional PCB, and a new structure with pluggable lens was considered for a high-efficient passive alignment. The structure was a lens-added optical waveguide for the improvement of misalignment between the lens and the waveguide in the alignment. Also, as it had a barrier-type structure to prevent the surface damage of the lens by desorption, the high-efficient passive alignment can be realized. The structure was designed by optimizing the simulation and the fabrication process of the pluggable lens structure was conducted using the repetitive photolithography and the thermal reflow. The optical waveguide with the lens-integrated pluggable interconnection was fabricated by the imprint process using the polydimethylsiloxane(PDMS) replica mold. Therefore, we confirmed the possibility of pluggable lens-added optical waveguide structure fabrication for high-efficient passive alignment.

Capacitance Dependence of Interdigital Capacitor on Amount and Type of Applied Liquid

In this paper design and fabrication of three types of interdigital capacitors are discussed, as well as influence of the liquid amount on their capacitance, and possibility of liquid type determination by using the fabricated structures. For faster and more reliable determination of capacitance in dependence of capacitor dimension and used substrate, a software tool called INDICON was developed. Capacitance of three structures fabricated in conventional PCB technology was determined by measuring S-parameters. Measurements were also performed by adding the exact amount of liquids on the capacitor surface. In addition, capacitance value in dependence of liquid amount is presented and possibility of applying this structure for detection of liquid amount is analyzed. Also, capacitance value in dependence of used liquid types was shown. For all measured and calculated values good agreement is achieved.

New Challenges in Testing and Failure Analysis for Microsystems-Enabled Photovoltaics Modules

Abstract Engineers at Sandia National Laboratories have developed a technology that may bring down the cost and improve the efficiency of photovoltaic energy conversion. Here they explain how they manufacture photovoltaic modules containing as many as 100,000 silicon solar cells using conventional IC fabrication and PCB assembly techniques. They also explain how they estimate module efficiency based on the IV characteristics of individual cells and the detection of open and short circuits.

COMm.PAT- Printed Antenna on a Non-Conventional Substrate for Communication

Antennas used for communication purpose have been grown recently using the direct printing methods to ensure light weight technology, ease of fabrication and simply available flexible substrates in the field of printed electronics. The use of flexible non-conventional substrates in this regard has been the current issue for the provision of same results obtained as that of using a conventional substrate. In this paper, we propose low cost printed antenna on a non-conventional substrate that provides higher read range (using ISM Band) for Real time location systems (RTLS) (for e.g. wireless sensing). This antenna makes use of the deployment techniques that involve the selection of environment friendly RF substrate thatcan be served by the localized networking companies in low cost.It further evaluates the substrate characteristics and mathematical properties using the EM Simulator Software (HFSS-High Frequency Structure Simulator) followed by the fabrication of antenna, both on a conventional PCB (FR4) substrate and on a non-conventional substrate (Kodak photo paper) having different materialistic properties using a direct write printing technology. The results include the resonant frequency and the input impedance matching for the feed on a Vector Network Analyzer.

Design of a Printed Dipole Antenna Array for a Passive Radar System

Passive radar (or Passive Coherent Localisation) is an advancing technology for covert operation. The signal transmitted from sources of opportunity such as radio or TV stations is used as illumination for a certain area of interest. Part of the transmitted signal is reflected by radar targets, for example, moving objects such as vehicles or aircraft. Typical radar parameters are derived from the comparison between the direct line-of-sight from the transmitter and the signal scattered from the target object. Such systems are an attractive addition to existing active radar stations because they have the potential to discover low-flying and low-observable targets and no active radar transmitter is required. Printed dipole antennas are very attractive antenna elements for such systems because of their easy fabrication, low-cost, polarisation purity, and low-profile properties. The present paper describes the design of an antenna array using printed dipole elements with flared arms for a passive radar system operating in the GSM900 frequency range. Isolated antenna elements and a small uniform linear antenna array were designed and optimised using computational electromagnetic methods. Several prototypes have been fabricated on conventional microwave PCB substrate material. Preliminary measurement results for antenna matching and far-field radiation patterns are shown.

Towards Fully Printed, Antenna-Based Proximity Sensors

In this work, we describe proximity sensors using functional coatings as sensing elements. The planar inductor-capacitor resonant circuit is fabricated by conventional PCB fabrication techniques an ...

RF 비아 구조를 이용한 K-대역 CMOS FMCW 레이더 칩용 고주파 패키지의 제작

In this paper, we design, fabricate and measure two kinds of high-frequency packages for K-band CMOS FMCW radar chips using RF via structures. The packages are fabricated with the conventional PCB process and LTCC process. The design centering of the packages is performed at 24 GHz and impedance variation caused by the wire bonding and RF via structure is fully evaluated using 3D electromagnetic simulation. The RF via structure with characteristic impedance of is used to reduce impedance mismatch loss. Two kinds of test packages with back-to-back connected RF paths are fabricated and measured for the design verification of the PCB-based package and LTCC package. Their measured results show an insertion loss of less than 0.4 dB at 24 GHz and less than 0.5 dB for 20~29 GHz. The measured return loss is less than -13 dB for the PCB-based package and less than -15 dB for the LTCC package in the frequency band, but the return loss of the package itself is predicted to be better than that of the test package by about 5 dB, because the ripples of the back-to-back connection typically degrade the return loss by 5 dB or more.

Three-Dimensional Architecture of Substrate Integrated Waveguide Feeder for Fermi Tapered Slot Antenna Array Applications

A class of three-dimensional planar arrays in substrate integrated waveguide (SIW) technology is proposed, designed and demonstrated with 8 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$\times$</tex></formula> 16 elements at 35 GHz for millimeter-wave imaging radar system applications. Endfire element is generally chosen to ensure initial high gain and broadband characteristics for the array. Fermi-TSA (tapered slot antenna) structure is used as element to reduce the beamwidth. Corrugation is introduced to reduce the resulting antenna physical width without degradation of performance. The achieved measured gain in our demonstration is about 18.4 dBi. A taper shaped air gap in the center is created to reduce the coupling between two adjacent elements. An SIW H-to-E-plane vertical interconnect is proposed in this three-dimensional architecture and optimized to connect eight 1 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\times$</tex></formula> 16 planar array sheets to the 1 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\times$</tex> </formula> 8 final network. The overall architecture is exclusively fabricated by the conventional PCB process. Thus, the developed SIW feeder leads to a significant reduction in both weight and cost, compared to the metallic waveguide-based counterpart. A complete antenna structure is designed and fabricated. The planar array ensures a gain of 27 dBi with low SLL of 26 dB and beamwidth as narrow as 5.15 degrees in the E-plane and 6.20 degrees in the 45 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$^{\circ}$</tex></formula> -plane.

Development of electro‐optical PCBs with polymer waveguides for high‐speed intra‐system interconnects

PurposeThe purpose of this paper is to study fabrication of optical‐PCBs on panel scale boards in a conventional modern PCB process environment. It evaluates impacts on board design and manufacturing with the developed optical board verifiers outlining challenges and requirements for manufacturing low‐loss waveguide structures and optical building blocks. The study aims to expand the current knowledge in the field by adding results obtained by utilizing industrial production infrastructure and developed scalable manufacturing processes to fabricate optical‐PCBs and board assemblies in high‐volumes and low‐cost manner.Design/methodology/approachImpacts on board design and manufacturing were studied with the developed optical technology verifiers. One verifier is optical‐PCB with embedded waveguides, integrated i/o couplers and optical vias. Another verifier is large size PCB with optical layer. A system‐level optical board assembly with 12.5 Gb/s Tx/Rx devices on surface mounted ball grid array (BGA) modules is designed for optical link analysis. Fabricated optical structures on verifiers are evaluated of their physical characteristics utilizing optical, SEM, LSCM analysis methods. Performance testing is conducted using standard optical transmission measurement methods and equipment.FindingsThe paper provides empirical results about fabrication of multimode optical waveguides with conventional PCB process equipment. Results suggest that current coating and imaging equipments are capable of producing optical waveguide patterns with high resolution and size accuracy. However, fabricators would require larger process window and defect tolerance for processing optical materials to obtain low‐loss waveguides with sufficient yields.Research limitations/implicationsBecause of the limited amount of design variants in production verifiers evaluated in this paper, some impacts like effect of base material, board construction, optical layer location and beam coupling solution were not evaluated. Likewise, impacts on long‐term stability and cost were not addressed. These factors however require further investigation to address technical feasibility of optical PCBs technology prior commercial high volume production.Practical implicationsThe paper includes implications for the development of a fabrication methods and testing procedures for optical polymer waveguide layers on PCBs.Originality/valueThis paper fulfils need to provide results on design, fabrication and characterization of optical PCBs and backplanes from industrial fabricator's perspective. The paper provides input for end‐user and developers to evaluate technical performance, robustness, and maturity of building blocks and supply chain to support polymer waveguide based technology for intra‐system optical links.

렌즈 일체형 광도파로를 이용한 고효율 수동 광 PCB 접속 구조 설계

Recently, by the increasing of data transmission rates, PCB is required high-speed data transmission rates and thin packaging. So optical PCB which is the combination of electrical layer and optical layer can be one of the solution to overcome the limitations of conventional electrical PCB. The most important factor in the implementation of optical PCB is optical interconnection. So the research on high-efficiency and passive alignment has been active. In this paper, we suggest built-in lens pluggable waveguide and we simulate its coupling efficiency and structural stability. Optical simulation results show that the proposed structure has higher efficiency than no lens structure about 1.86 times in transmitter and about 1.42 times in receiver. In structure simulation, inner lens has no damage in desorption process. Therefore, we shown that the proposed structure has a high coupling efficiency and structural stability.

Evaluation of a quasi‐coaxial printed circuit board transformer

PurposeThe purpose of this paper is to investigate the possibility of utilizing printed circuit board (pcb) technology to manufacture coaxial transformers and to increase the predictability, accuracy and repeatability of the transformers leakage inductance.Design/methodology/approachThe geometry of a coaxial transformer is approximated using pcb techniques. Several different geometries are presented with the outer coaxial conductor being approximated by discrete conductors varying from four to 36 in number. Finite element methods as well as experimental results are used to support the proposed ideas. A planar transformer is also analyzed in the same way to emphasize the design advantages offered by the proposed quasi‐coaxial transformer.FindingsThe proposed multi‐conductor structures can be applied as co‐axial transformers. The experimental values obtained for the leakage inductance of the coaxial structures correspond well to the predicted values. This is not the case for conventional planar structure where adjustments need to be made in the finite element analysis simulations to accommodate the shortcomings of the analytical calculations.Originality/valueIn applications where the prediction of the leakage inductance of a transformer is important, this method may be applied and has the advantage of conventional pcb manufacture techniques.

High-reliability flexible optical printed circuit board for opto-electric interconnections

A rigid flexible optical electrical printed circuit board (RFOE-PCB) with both electrical layers and an optical layer was fabricated using a conventional PCB manufacture process. The RFOE-PCB is applicable to fold-type mobile devices such as mobile phones and laptop computers. The RFOE-PCB was designed to be embedded with a flexible 45-deg-ended optical waveguide, which was made using a polymeric material. The precise lamination between an electrical layer and an optical layer was achieved by a passive alignment method. We carried out the repetitive folding test and an environment test for physical and optical reliability suitable for mobile devices. Data transmission of 2.5 Gb/s was demonstrated with a clear eye diagram using the fabricated RFOE-PCB.

Fabrication and Reliability of Rigid-Flexible Optical Electrical Printed Circuit Board for Mobile Devices

A rigid-flexible optical and electrical printed circuit board (RFOE-PCB) was fabricated using a conventional PCB manufacturing process for mobile devices. The RFOE-PCB was designed to be embedded with a flexible 45-ended optical waveguide. In order to apply it to mobile devices, a repeating folding test and an environment test were carried out for physical and optical reliability. The RFOE-PCB successfully passed the reliability tests.

Soft-lithography-based Inter-chip Optical Interconnects

The increasing performance of microprocessors leads to higher bandwidth require- ments for the data ∞ow to and from the processor. Today, all signaling on a PCB is performed electrically, using copper lines that are integrated in the board. However, issues such as prop- agation loss and inter-channel crosstalk limit the scalability of electrical interconnects to ever higher bandwidth densities. Optical interconnects feature a higher bandwidth £ length prod- uct, are more power-e-cient and enable a higher bandwidth density than electrical interconnects do. This paper describes a kind of two-dimensional monolayer optical interconnects providing interconnections between chips on conventional PCB. We have designed a soft-lithography-based, versatile coupling structure with a 45 - total internal re∞ector (TIR), a beam duct, and a polymer waveguide in order to vertically couple light beams between transmitter (or receiver) and the waveguide layer. This proposed integrated architecture of a polymeric optical interconnection has been demonstrated to be advantageous in the aspects of misalignment tolerance, ease and low cost of fabrication, as well as relative simplicity in deployment. We also investigated the characteristics of in-plane connections including cross-over and branching nodes in the optical interconnects with experimental and theoretical analysis. The theoretical crosstalk, as calculated by a function of crossing angle, was determined for a set of interconnect pairs with varying cross- sections, and was compared with experimental measurements. Furthermore, a suitable branching angle was found for branching node and the efiects of short-distance mode scrambling in highly multimode polymer waveguides were studied in detail in this paper too.

Optical Pattern Inspection for Flex PCB — Challenges & Solution

Due to the material properties and technology advancement in printed circuit flex tapes, traditional PCB inspection algorithms using reference image cannot be used. Flex tapes are flexible circuits enabling the design and production of lighter, faster and smaller electronic products. A flex tape is made of flexible polymer film that is laminated onto a thin sheet of conductive material and etched to produce a circuit pattern. The width of fine pitch patterns can be of a few microns. Due to the material characteristics of printed circuit tapes, such as thinness and flexibility, the images captured during inspection are distorted (stretch or shrink, tilt, meandering, etc.). These anomalies and shining tape surface make the possibility of using conventional PCB inspection algorithms using referential methods for pattern inspection, difficult.The goal of pattern inspection is to identify pattern defects — open, short, nick, protrusion, island, pinholes and dust particles. Non-repetitive and non-uniform distortions are some of the main challenges in inspecting these flexible tapes. Some of the other challenges faced during the design of the defect detection algorithm are non-uniform lighting and the gamut of sizes, shapes & orientation of defects as well as features on the printed circuit. Moreover, the algorithms need to take into account the stringent defect tolerance limits followed by the industry.

Reading a GEM with a VLSI pixel ASIC used as a direct charge collecting anode

In MicroPattern Gas Detectors (MPGD) when the pixel size is below 100 μ m and the number of pixels is large (above 1000) it is virtually impossible to use the conventional PCB read-out approach to bring the signal charge from the individual pixel to the external electronics chain. For this reason a custom CMOS array of 2101 active pixels with 80 μ m pitch, directly used as the charge collecting anode of a GEM amplifying structure, has been developed and built. Each charge collecting pad, hexagonally shaped, realized using the top metal layer of a deep submicron VLSI technology is individually connected to a full electronics chain (pre-amplifier, shaping-amplifier, sample & hold, multiplexer) which is built immediately below it by using the remaining five active layers. The GEM and the drift electrode window are assembled directly over the chip so the ASIC itself becomes the pixelized anode of a MPGD. With this approach, for the first time, gas detectors have reached the level of integration and resolution typical of solid-state pixel detectors. Results from the first tests of this new read-out concept are presented. An Astronomical X-ray Polarimetry application is also discussed.

Reading a GEM with a VLSI pixel ASIC used as a direct charge collecting anode

In MicroPattern Gas Detectors (MPGD) when the pixel size is below 100 μ m and the number of pixels is large (above 1000) it is virtually impossible to use the conventional PCB read-out approach to bring the signal charge from the individual pixel to the external electronics chain. For this reason a custom CMOS array of 2101 active pixels with 80 μ m pitch, directly used as the charge collecting anode of a GEM amplifying structure, has been developed and built. Each charge collecting pad, hexagonally shaped, realized using the top metal layer of a deep submicron VLSI technology is individually connected to a full electronics chain (pre-amplifier, shaping-amplifier, sample & hold, multiplexer) which is built immediately below it by using the remaining five active layers. The GEM and the drift electrode window are assembled directly over the chip so the ASIC itself becomes the pixelized anode of a MPGD. With this approach, for the first time, gas detectors have reached the level of integration and resolution typical of solid-state pixel detectors. Results from the first tests of this new read-out concept are presented. An Astronomical X-ray Polarimetry application is also discussed.

Optical interconnection using fiber-embedded boards and connection blocks fabricated by a micro-grooving technique for fiber insertion

We fabricated fiber-embedded boards using a micro-grooving technique for optical interconnects. This approach is quite cost effective and fully compatible with conventional PCB processes. U-shaped grooves were formed on FR-4 plates using a 90° V-shaped diamond blade. Polyimide-coated glass fibers were inserted in the grooves followed by a conventional lamination process. The 12 fibers embedded in the board showed a good uniformity in their position with a fluctuation below ±8 µm. Optical connection blocks were also fabricated using fiber segments embedded in a grooved silicon wafer piece in order to couple the light between a transmitter/receiver module and a fiber-embedded board. 45° mirrors were formed at the end of the connection blocks by mechanical polishing. An optical link of 2.5 Gb s−1 signals with a high coupling efficiency was demonstrated through the fiber-embedded connection blocks and a board.