Experimental analysis of grounded coplanar waveguide structures based on different PCB processes with uncertainty analysis

The rapid development of information and communication technologies has driven the rapid growth of data traffic and the large requirement of high-speed optical transceiver modules. Usually, optical subassemblies through flexible printed circuit boards (PCBs) connect with the hard PCBs to compose as optical transceiver modules. Because of the impedance mismatch of connection between flexible PCB and hard PCB, the operation bandwidth of the module can be limited. In this paper, the design of connection between flexible PCB and hard PCB in optical subassembly modules will be investigated for increasing the operation speed of the module. First, the transmission bandwidth of flexible PCB is analyzed. High-frequency performances of three transmission line structures, micro-strip line, grounded coplanar waveguide, and top ground micro-strip line, are investigated in flexible PCB. High-frequency performances of flexible PCB with different bending types are also investigated. The flexible PCB has been verified to be suitable to use in 25 Gb/s applications. Next, the high-speed transmission performance is analyzed through the connection between flexible PCB and hard PCB, because the impedance mismatch usually occurs at the connection. The ground pads are added near the signal line of flexible PCB, and the ground pads are connected to the ground layer in PCB through ground vias. The anti-pad in hard PCB is added under the signal solder pad. The dip of S21 response can be eliminated by the optimized ground pad. The impedance mismatch can be reduced by the optimized anti-pad, the impedance increases from 40-Ω to 49-Ω at the connection between flexible PCB and hard PCB, and the transmission bandwidth can increase from 16.5 GHz to 23.5 GHz. TO-46 header is a common and low-cost packaging solution for DFB laser and photodiodes. The connection between flexible PCB and TO-46 header is also investigated. While the connection has a gap, the dip of frequency response will occur at lower frequency. While the connection is very close, the bandwidth can be larger than 25 GHz. The flexible PCB, hard PCB, and TO-46 header are combined together, and the 23 GHz transmission bandwidth can be obtained. The 25 Gb/s transmission eye diagram is also measured, and the eye height, rise time, fall time, and Q-factor are 268.14 mV, 13.78 ps, 13.56 ps, and 8.76, respectively. The combined flexible PCB, hard PCB, and TO-46 header are verified to be suitable to apply in 25 Gb/s optical subassembly modules, and will be able to be used in 100G Ethernet.

A printed circuit board (PCB) is an essential element for practical circuit applications and its failure can inflict large financial costs and even safety concerns, especially if the PCB failure occurs prematurely and unexpectedly. Understanding the failure modes and even the failure mechanisms of a PCB failure are not sufficient to ensure the same failure will not occur again in subsequent operations with different batches of PCBs. The identification of the root cause is crucial to prevent the reoccurrence of the same failure. In this work, a step-by-step approach from customer returned and inventory reproduced boards to the root cause identification is described for an actual industry case where the failure is a PCB burn-out. The failure mechanism is found to be a conductive anodic filament (CAF) even though the PCB is CAF-resistant. The root cause is due to PCB de-penalization. A reliability verification to assure the effectiveness of the corrective action according to the identified root cause is shown to complete the case study. This work shows that a CAF-resistant PCB does not necessarily guarantee no CAF and PCB processes can render its CAF resistance ineffective.

The research object in the work is the printed circuit boards (PCB) Production technological process using the additive technology of photopolymer 3D printing. The existing problem is that the manufacturing process of single-sided and double-sided PCBs, simple in technology, from the third to the fifth accuracy class, requires the use of a large amount of consumables and technological equipment. In turn, this affects the cost of the product. The research subject is models and methods for manufacturing PCB using photopolymer 3D printing. In order to reduce the cost of materials: film or aerosol photoresist, as well as reduce the number of technological operations, applying photoresist and for the manufacture of PCBs stencils, it is proposed to use photopolymer 3D printing technologies for the manufacture of PCBs. The paper analyzes the costs of Plexiwire Resin Basic Orange Transparen photopolymer resin for the manufacture of single-sided PCBs and calculates the cost of the consumable (resin) compared to the costs of dry film photoresist. 60 % cost of consumables (photopolymer resin) compared to dry film photoresist for making single-sided PCBs. The work is aimed at determining the dependence of the geometric dimensions of the PСВs topology and the consumption of photopolymer resin on the technological parameters of photopolymer exposure. A regression correlation model of the dependence of resin consumption on exposure parameters has been developed and correlation coefficients have been calculated. It has been established that with an increase in the exposure time of the photopolymer resin, the consumption of the photopolymer resin increases and the deviation of the geometric dimensions of the PCBs topology increases, which in turn negatively affects the quality of the product. Therefore, using the obtained regression model, it is possible to calculate the influence of parameters on the PCB topology and reduce the deviation of conductor sizes and resin consumption.

With the rapid development of electronics industry, the printed circuit board (PCB) is the most important indispensable components for various kinds of products such as military, medical, appliances and consumer electronics. At the beginning, the construction of integration of electronic components by PCB process is single layer and double layer process. Until now, the yield of multilayer process with a lot of packaging technology is very high and the stability is good. However, all the traditional PCB process is photolithography process. This procedure is not only using a lot of chemicals and special materials, but also making a variety of organic and heavy metals pollutions. Besides, the equipment of photolithography process is very expensive. Therefore, the target of electronics industry in the future are green manufacturing process and relatively low equipment costs.

Recently, PCB(Printed Circuit Board) is required more high precision, function and miniaturization for advanced electronics, display, semiconductor and packaging, etc. and this complex PCB needs cutting, repair, trimming and structuring, etc. So, we make complex machine that is possible this all PCB processing and test PCB material processing using developed machine. This machine consists of UV nano-second pulse laser, power controller(self-developments), probe stage for trimming, auto focusing and scanner. The power controller is possible to monitor real-time power and adjust precision laser power. Using various parameters such as laser power, scanning speed, repetition rate and pulsed overlaps can obtain for process result having high precision and speed.

With the rapid development of electronic manufacturing industry in China, defect detection of printed circuit board (PCB) is particularly important in order to improve its quality and reduce its production cost. The cost of PCB has always been discussed in depth by practitioners, but there are few fixed models for replication, although confidentiality is the key reason. However, due to the long process of PCB and the variety of products, it is really difficult to be comprehensive. Therefore, based on the cloud platform, the author studies the PCB cost data system. Research shows that the cloud-based PCB cost data system allows management to master energy consumption data more effectively and in real time, effectively grasp the monitoring reports of production costs and energy consumption, and control the production equipment in a safe state in real time. Improve management capabilities.

CNC PCB Milling and Wood Engraving Machine incorporates the plan and usage of a CNC (Computer Numerical Control) machine to make PCB (Printed Circuit Board) and wood etching machine in a solitary set up. Creation of PCB in the present market is intensely costly when manufacture of testing circuits is considered. Along these lines, this CNC PCB Milling machine would be an effective instrument through which circuit can be scratched and penetrated at a reasonable cost. The creation of this CNC machine is to diminish the cost and multifaceted nature of machine. This venture manages the plan of programmed scaled down CNC machine for PCB drawing and processing. The proposed venture would be profoundly practical in contrast with that of customary manufacture hardware.

A 28 GHz air-filled cavity-backed microstrip antenna array, which is embedded in a polyphenyl ethers (PPE)-based multilayer printed circuit board (PCB), is presented. The air cavity is implemented by a novel 2.5D PCB process with a no-flow prepreg, to improve radiation efficiency, bandwidth, and directivity while maintaining a low profile. A four-element antenna array was designed, simulated, and measured. The measurement results yield a bandwidth of 3.8% centered at 28.5 GHz and a realized gain of 14.8 dBi with the antenna substrate thickness of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$0.035\lambda_{0}$</tex> and the separation of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$0.8\lambda_{0}$</tex> between elements. Network analysis for a single patch section of the designed antenna with transmission line (TL) models is discussed as well. The comparison between the analyzed, simulated, and measured input impedance shows a good agreement over the given frequency band.

In order to achieve the shorter circuit design of multiple chips, three-dimensional (3D) packaging technologies with through silicon vias were developed to achieve high performance, low power consumption and small packaging size. In this paper, a PCB (Printed Circuit Board) processing compatible structure of three-dimensional chip stacking with low cost and easy fabrication will be shown. 3D and through Si via connections were formed by UV laser drilling technology. Laser drilling is a non-contact manufacture method and laser beam with high energy can be focused to a small spot (15 mum beam diameter) for material ablating and removing without mask used. Several processes are the keys to accomplish 3D stacking, such as wafer thinning process, through silicon via forming process, dielectric layer forming process, metallization process, and inter chips bonding process. By integration of the mentioned key processes, a 3D chip stacking structure with 10 layers was carried out. The thickness of chip was 100 mum. Daisy chain pattern was designed for the electrical measurement of 3D stacking structure. The testing results show that the resistance of multi- chip stacking structure is about 0.056 Omega/cm. Some reliability test, such as temperature cycling test and pressure cooker test were also done. These testing results verified this PCB processing compatible 3D chip stacking technology with low cost is a reliable structure for 3D SiP (System in Packaging) module application.

Plasma treatment of printed circuit board (PCB) is a common step in the electronic packaging processes in order to modify the surface and enhance its adhesion to molding compound. In this paper, PCB surface modifications resulting from plasma treatment were investigated by chemical and mechanical analysis methods. The PCB substrate in consideration was for multichip package, consisting of a core layer sandwiched by solder resist (SR) material, which in turn was composed of epoxy, acryl resins, and several kinds of fillers. Argon was employed as a plasma gas and the number of times that the plasma treatment was applied was chosen as a variable to estimate the effect of repeated exposure to the SR surface during the manufacturing process. The resulting surface conditions were analyzed using roughness measurement, water contact angle measurement, X-ray photoelectron spectroscopy (XPS), nano-indentation, and nano-scratch test method. Comprehensive analyses made it possible to understand the characteristics of the effect of plasma on the PCB surface, i.e., SR material. It was found that the surface roughness after the one-time plasma treatment increased from ~ 62 to ~ 90nm, then decreased more or less to the initial level after three and eight times of repeated treatments. These roughness trends were explained by cleaning out contaminants accumulated in the surface crevices and then preferentially removing or melting away a thin resin layer from the peaks on the surface. The plasma treatment decreased the contact angle significantly and increased work of adhesion. Chemical analysis of these surfaces by XPS showed that the C-C bonds in SR were broken, the population of the polar groups such as O-H, C=O, and COOH increased, and the oxygen content increased. The polar groups increased surface energy, and resulted in increased PCB adhesion with the epoxy molding compound (EMC). Mechanical analysis by nano-indentation and nano-scratch test showed that the surface became soft and weak if plasma treatment was too excessive. In this case, a plasma affected zone corresponding to the severe C-C bond breakage was formed near the surface and the adhesion with EMC suffered. Therefore, caution should be exercised in determining the degree of plasma treatment needed.

&lt;span&gt;The rapid progress of technology has imposed significant challenges on Printed Circuit Boards (PCB) designers. Once of those challenges is to satisfy the electromagnetic compatibility (EMC) compliance requirements. For that reason, EMC compliance must be considered earlier at the design stage for time and cost savings. Conventionally, full wave simulation is employed to check whether the designed PCB meets EMC standards or not. However, this method is not a suitable option since it requires intensive computational time and thus increasing the unit cost. This paper describes novel analytical models for estimating the radiated emissions (RE) of PCB. These models can be used to help the circuit designer to modify their circuit based on the maximum allowable RE comparing to the relevant EMC-RE standard limit. Although there are many RE sources on PCB, this paper focuses on the significant source of RE on PCB; namely PCB-traces. The trace geometry, termination impedance, dielectric type, etc. can be specified based on the maximum allowable emissions. The proposed models were verified by comparing the results of the proposed models with both simulation and experimental results. Good agreements were obtained between the analytically computed results and simulation/measurement results with accuracy of ±3dB.&lt;/span&gt;

In this age of ever increasing data rates in communication systems, optics are becoming more commonplace for long length (>10m) signal transmission in High Performance Computing (HPC) systems due to their bandwidth capabilities which are higher than their electrical counterparts. In these optical based communication systems, Vertical Cavity Surface Emitting Lasers (VCSELs) are the most commonly used communications lasing medium for multimode fiber applications. These lasers are active in the 850 nm region, with speeds commonly at 10 Gbps/channel. VCSEL vendors are now commercializing lasers at 25 Gbps/channel as well, with research groups actively pursuing rates beyond 40 Gbps/channel, demonstrating that these communications technologies will likely be continuously incorporated in multiple generations of HPC systems. For optical based signaling technologies, fiber optics are typically utilized as the medium of choice for point to point contacts due to their low loss characteristics, stability to thermal degradation and aging, and manufacturability. Fiber optics have become a commodity, making them inexpensive. However, the high precision connection technologies required to bring light off of VSCELS and fiber to fiber are still rather expensive, limiting some of the optical applications in products. Polymer waveguides offer the promise to act as an enabling technology to provide highly complex optical routing that can be passively connected, lowering system costs and allowing next generation systems to be optically driven. For this to become a reality, polymer waveguide materials must meet multiple requirements in the communications industry. The focus of this thesis is on the understanding and optimization of the manufacturing requirements of polymer waveguide materials, their optical stability to existing standards such as Telecordia, and the impacts that printed circuit board processes have on them.

Electronic Manufacturing Service (EMS) Providers, Printed Circuit Board (PCB) Fabricators and Defense Contractors are spending millions creating and maintaining International Traffic in Arms Regulations (ITAR) compliant systems and processes while at the same time lobbying for change to theoretically improve US competitiveness in foreign markets. What is it within the ITAR that adds cost to the EMS industry and/or the PCB process? Are those costs real or perceived? How can the industry better serve the needs of the Defense Market? What are the inherent challenges of outsourcing in an ITAR environment?

Cavity model with segmentation method is extended to the analysis of radio frequency interference (RFI) problems in a shielding enclosure with printed circuit boards (PCBs) . Sixteen different Green's functions, instead of one in the conventional segmentation method developed for PCB cavities, are introduced to describe the fields in various cavities formed by enclosure walls and PCB copper planes. Both horizontal and vertical connections among these cavities are achieved by enforcing the boundary conditions along their common interfaces. Numerical examples demonstrate the efficiency and accuracy of the method by compared with full wave simulations.

Based on the method of moments (MoM), radio frequency (RF) ground voltage drop of any signal return path on printed circuit board (PCB) is modeled numerically. The full-wave treatment provides the flexibility in predicting RF ground voltage drop of non-ideal ground return, such as holes and slots in the ground plane. An example is given to illustrate the application aspect of RF ground voltage prediction for EMC design purposes. I. INTRODUCTION With ever-increasing operating speeds of electronic circuits, the effects of interconnects of printed circuit boards (PCBs) become significant and have to be accounted for in the design. Hence, accurate modeling of interconnects on PCB is gaining more attention in high- speed circuit design. Conventionally, a ground plane of a PCB as return path for signal trace is assumed to be ideal with zero potential difference. Usually, the voltage drop on a signal delivery path (signal and ground conductors) is usually lumped into the signal conductor for circuit analysis purposes. Hence, information on ground voltage drop of any signal delivery path is not readily available. As logic devices switch at very high speed and draw large amount of current during switching (very high di/dt), significant voltage drop in the ground conductor is expected even its inductance is very small (1)-(8). Therefore, additional information on ground voltage drop or ground bounce provides an assessment on the effectiveness of a specific ground design for high-speed circuit so that potential EMI problem can be identified and rectified. Most commercially available full-wave electromagnetic simulation tools are based on either finite element method (FEM) (9), method of moments (MoM) (10) or finite-difference time-domain (FDTD) method (11). These tools usually model interconnects as a two- port network, which is usually good enough for signal integrity analysis purposes but does not provide additional information on ground voltage drop. To predict the RF ground voltage drop of any arbitrary signal delivery path on PCB, full-wave treatment in the modeling is the only way to model it accurately. In this paper, a full-wave approach to model the RF ground voltage drop based on MoM is presented. With