Copper Traces Research Articles

3D Printed PCB Microfluidics.

The combination of printed circuit boards (PCB) and microfluidics has many advantages. The combination of electrodes, sensors and electronics is needed for almost all microfluidic systems. Using PCBs as a substrate, this integration is intrinsic. Additive manufacturing has become a widely used technique in industry, research and by hobbyists. One very promising rapid prototype technique is vat polymerization with an LCD as mask, also known as masked stereolithography (mSLA). These printers are available with resolutions down to 35 µm, and they are affordable. In this paper, a technology is described which creates microfluidics on a PCB substrate using an mSLA printer. All steps of the production process can be carried out with commercially available printers and resins: this includes the structuring of the copper layer of the PCB and the buildup of the channel layer on top of the PCB. Copper trace dimensions down to 100 µm and channel dimensions of 800 µm are feasible. The described technology is a low-cost solution for combining PCBs and microfluidics.

Self-Folding PCB Kirigami: Rapid Prototyping of 3D Electronics via Laser Cutting and Forming.

This paper demonstrates laser forming, localized heating with a laser to induce plastic deformation, can self-fold 2D printed circuit boards (PCBs) into 3D structures with electronic function. There are many methods for self-folding but few are compatible with electronic materials. We use a low-cost commercial laser writer to both cut and fold a commercial flexible PCB. Laser settings are tuned to select between cutting and folding with higher power resulting in cutting and lower power resulting in localized heating for folding into 3D shapes. Since the thin copper traces used in commercial PCBs are highly reflective and difficult to directly fold, two approaches are explored for enabling folding: plating with a nickel/gold coating or using a single, high-power laser exposure to oxidize the surface and improve laser absorption. We characterized the physical effect of the exposure on the sample as well as the fold angle as a function of laser passes and demonstrate the ability to lift weights comparable with circuit packages and passive components. This technique can form complex, multifold structures with integrated electronics; as a demonstrator, we fold a commercial board with a common timing circuit. Laser forming to add a third dimension to printed circuit boards is an important technology to enable the rapid prototyping of complex 3D electronics.

Improvement of discharge system in cool plasma sintering method for copper fine traces

As a wiring material for printed electronics (PE), copper is strongly needed instead of silver. For a sintering method of copper traces, we have developed the method using oxygen pump and atmospheric pressure plasma, and demonstrated the ink composed of nanoparticles can be sintered to bulk-like structure. In this study, we have improved the sintering system to make it effective especially for copper inks made of submicron particles. We have tried to increase the thickness of the sintered layer and decrease the resistivity by changing the power supply system of plasma discharge and increasing the plasma density. The improved system has successfully demonstrated that a copper trace at least 4 μm thick can be sintered and that the resistivity decreases to approximately 3.3 μΩ·cm. These results can lead to huge breakthroughs in PE based on copper.

Active attitude control for microspacecraft; A survey and new embedded designs

Novel technologies and design techniques of the active attitude control systems (ACS) for microspacecraft are briefly covered in this survey. Electric propulsion (EP) thrusters for satellites orbit correction and interplanetary vehicles acceleration have recently emerged as the focal point and front subject in propulsion fields due to their low mass, low cost and high specific impulse. Therefore, micro propulsion thrusters are explored for small satellites in terms of its performance, lifetime and future prospects. The focus of the review is at the center of research published in the last few years and state-of-the-art design concepts in terms of control, reliability, fault analysis and response to failure has been discussed for reaction wheels and magnetorquers. Finally, novel embedded planar magnetorquers which are integrated inside the internal layers of PCB for providing attitude maneuverability to various small satellites are discussed and simulated for critical tasks such as damping the initial angular velocities after vehicle launch. As the proposed magnetorquers are integrated in the form of copper traces, thermal analyses are done to maintain the temperature gradients.

Laser-Assisted Selective Fabrication of Copper Traces on Polymers by Electroplating.

The selective deposition of metals on dielectric materials is widely used in the electronic industry, making electro-conductive connections between circuit elements. We report a new low-cost laser-assisted method for the selective deposition of copper tracks on polymer surfaces by electroplating. The technique uses a laser for the selective modification of the polymer surface. The electrical conductivity of some polymers could be increased due to laser irradiation. Polyimide samples were treated using nanosecond and picosecond lasers working at a 1064 nm wavelength. An electro-conductive graphene-like layer was formed on the polymer surface after the laser treatment with selected parameters, and the copper layer thickness of 5–20 µm was deposited on the modified surface by electroplating. The selective laser-assisted electroplating technology allows the fabrication of copper tracks on complex shape dielectric materials. The technology could be used in the manufacturing of molded interconnect devices (MID).

A Systematic Analysis of Printed Circuit Boards Bending during In-Circuit Tests

When performing In-Circuit Tests (ICTs) of Printed Circuit Boards (PCBs), there are certain phenomena related with strain analysis that must be known in order to obtain stronger and more accurate testing results. During testing, PCBs are often subjected to mechanical bending efforts that induce excessive strain. This study focuses on the building of a Finite Elements Analysis (FEA) methodology that prevents excessive bending strain in critical points of a PCB during an ICT. To validate this methodology, a set of experimental tests, matched with a set of FEA, were carried out. Thus, companies, before the development of an ICT machine (fixture), will be able to use this FEA methodology to predict whether the maximum strain of a PCB under study, when subjected to its ICT, will damage it, thus reducing unnecessary production costs. A guideline was thus designed to enable the creation of the most representative Finite Elements Model (FEM) for any PCB, based on its amount and direction of copper traces.

Novel polarization independent multiband THz perfect metamaterial

AbstractThe design and characterization of a multiband THz metamaterial are reported in this article. The proposed metamaterial is constructed over the polyimide substrate embedded with a novel ring‐shaped frequency‐sensitive copper trace on the top providing the desired frequency response. The proposed metamaterial is developed from a unit cell with a base cross shape. The arms of the cross shape are deployed with three folded circular resonators providing the desired frequency‐selective property. The proposed metamaterial offers band‐stop characteristics at 0.83, 2.15, 2.91, 4.1, and 4.86 THz. The proposed unit cell metamaterial has the smallest foot‐print of 0.089λo × 0.089λo where λo is the free‐space wavelength. The electric field distribution and surface current contours are used to describe the operation of the proposed metamaterial. The proposed metamaterial has a symmetric configuration resulting in a polarization‐independent operation. The angular stability of the proposed metamaterial is investigated by subjecting the metamaterial to the various oblique incidence of THz radiation. The proposed THz metamaterial unit cell is suitable for THz imaging and spectroscopy applications.

Investigation into thermo-mechanical reliability of copper trace lines in stacked dies ball grid array packaging

The persistent trend toward device miniaturization in the semi-conductor field has led to an ever finer line width and spacing of the copper trace patterns in the organic substrate used to connect the chip and printed circuit board. Thus, copper trace fracture has emerged as a major concern during the manufacturing process or subsequent thermal cycle reliability testing stage. Accordingly, the present study develops a three-dimensional (3D) computational model to analyze the reliability of the copper trace lines in a stacked ball grid array (BGA) containing two dies under thermal cycling between −65 °C and 150 °C. The simulation model takes account of both the tensile mechanical strength of the copper trace and its creep behavior at elevated temperatures. The validity of the simulation model is confirmed by comparing the predicted distribution of the plastic work density (PWD) in the copper trace/substrate layer following thermal cycling with the experimental observation. In general, the results show that the maximum average PWD of the copper trace should not exceed 400 kJ/m3 in order to minimize the risk of trace fracture. Taguchi analysis experiments are performed to determine the optimal design of the stacked BGA package which minimizes the PWD and hence maximizes the fatigue life of the copper trace. The results indicate that the thermo-mechanical reliability of the stacked BGA package depends mainly on the choice of substrate core material and core trace thickness.

Estimation of Heat Generation in Semiconductors Centrally Mounted on Printed Circuit Boards

This work proposes a method to estimate the heat dissipation of components that are centrally soldered to printed circuit boards (PCBs). The power losses of a ball grid array (BGA) package and a MOSFET are estimated via a 1-D thermal model in tandem with a heat flux sensor. The former device is soldered to a multilayer PCB with complex copper traces, whereas the latter is mounted on a PCB without internal copper layers and relatively simple trace patterns. Thermal analyses demonstrate that the 1-D model is capable of representing heat conduction with good agreement in the board without internal copper layers. However, the multilayer PCB requires an adjustment coefficient based on the thermal conductance of the board. Said coefficient is employed to adjust the effective heat transfer coefficient of the multilayer PCB. With the aid of the adjustment coefficient, results show that the 1-D thermal model in combination with a heat flux sensor is capable of predicting heat dissipation within 15% of the actual power loss for both devices.

Determination of 18 Trace Elements in 10 Batches of the Tibetan Medicine Qishiwei Zhenzhu Pills by Direct Inductively Coupled Plasma-Mass Spectrometry.

Qishiwei Zhenzhu pills (QSW) was first recorded in the Tibetan medicine classic Si Bu Yi Dian and has been used to treat “Baimai” disease, stroke, paralysis, hemiplegia, cerebral hemorrhage, and other diseases till today. This prescription contains more than 70 medicines including myrobalan, pearl, agate, opal, bezoar, coral, musk, gold, silver, and a mineral mixture Zuotai. As a result, QSW contains a large amount of mercury, copper, lead, and other trace elements. The aim of this study was to determine the 18 trace elements (lithium, beryllium, scandium, vanadium, chromium, manganese, cobalt, nickel, copper, arsenic, strontium, argentum, cadmium, cesium, barium, lead, aurum, and mercury) in 10 batches of QSW produced by 5 pharmaceutical companies (Ganlu Tibetan Medicine Co., Ltd. has 6 different batches) by direct inductively coupled plasma-mass spectrometry (ICP-MS). ICP-MS is a rapid, sensitive, accurate methodology allowing the determination of 18 elements simultaneously. The results showed that each element had an excellent linear relationship in the corresponding mass concentration range. The results showed that the rank order of the elements in QSW was copper > mercury > lead from high to low, with the mass fraction higher than 6000 μg/kg; the mass fractions of argentum, arsenic, manganese, aurum, strontium, barium, chromium, and nickel were in the range of 33–1034 μg/kg; and the mass fractions of vanadium, cobalt, lithium, beryllium, cadmium, scandium, and cesium were lower than 10 μg/kg. The reproducibility from the same manufacturer (Tibet Ganlu Tibetan Medicine Co., Ltd.) was relatively high; however, the element amounts among 5 manufacturers were different, which could affect the efficacy and toxicity of QSW. All in all, ICP-MS can be used as an effective tool for the analysis of trace elements in QSW and standard quality control needs to be enforced across different manufactures.

The Salcombe metal cargoes: New light on the provenance and circulation of tin and copper in Later Bronze Age Europe provided by trace elements and isotopes

Since the mid-1970s a Bronze Age assemblage of metal objects has been recovered from the seabed off the south Devon coast at Salcombe, southwest England. The assemblage spans two suspected shipwreck events and comprises nearly 400 pieces of raw materials and finished artefacts, primarily in copper, tin, bronze and gold. Among these are 280 copper and 40 tin ingots, by far the largest discovery of Bronze Age ingots in either metal from northwestern Europe. Research in recent years revealed the microstructural and chemical nature of the ingots and enabled some preliminary conclusions on the metals trade in Europe in the Later Bronze Age. The present study aims to extend this knowledge by determining the tin, copper and lead isotopic compositions of the ingots using HR-MC-ICP-MS. In addition, bronze artefacts (swords, rapiers, palstaves and weights) from the Salcombe site are included in the multi-proxy approach in order to investigate their history and the possible relationships between finished products and ingots. In combination with the available chemical data of previous studies, the current results of the tin metal show that most likely two tin sources in southwest Britain supplied the ore for their production. This also sheds light on Late Bronze Age tin ingots from Israel that share the same geochemical characteristics with one group of the finds from Salcombe. Although the tin in the bronzes is similar to the tin in the ingots, it is not certain that the latter were used to make the bronzes. Correlations of copper and tin isotopes and trace elements of the bronzes point to a mixing or even recycling of copper-tin alloys rather than the alloying of individual components of copper and tin. However, the copper ingots from the assemblage could have been an additional component in the mixing process given their impurity pattern and isotopic composition. At the same time, a close relationship between swords of the Rosnoën type and palstaves from the cargo is disclosed. Lead isotope ratios for their part suggest Sardinian and/or south Spanish copper ores as a source for both the copper ingots and the copper of the bronzes. This would mean long-distance metal trade in the Later Bronze Age in both cases and would provide new insights into the interpretation of the prehistoric networks in Europe.

Impact of surface reactance and skin depth for effective surface wave-based communication between the integrated circuits of printed circuit board

The copper traces for printed circuit board (PCB) applications proved to be less suitable for high frequency communications. Surface wave communication-based wave guide with the properties of high field confinement at its conductor and the dielectric interface along with less dispersion, suits well for inter chip communication at higher frequencies. For effective wave propagation through the proposed channel, an analysis on the surface reactance and skin depth is required, which also accounts for proper channel construction. This research focuses mainly on these parameters to come up with the optimal channel design conditions. From the complete analysis, the high surface reactance of the channel with lower skin depth levels gives path to high channel propagation efficiency, keeping the height of the dielectric to a particular level, and the optimal surface power integration throughout the channel is achieved. The analysis was performed considering different frequency levels ranging from 100 GHz to 500 GHz. Considering surface reactance over the j100 to j400 range, which results in power integration up to 99.6% at the interface of conductor and dielectric, it is better than the theoretical values of copper traces.

Experiments and failure analysis of a charged board event on a hard disk drive printed circuit board assembly

A charged board event on a hard disk drive printed circuit board assembly was experimentally measured under the charged device model concept. Electrostatic discharge sensitivity was measured and used for establishing an electrostatic discharge control program for a hard disk drive assembly process. The results revealed that a sample printed circuit board was damaged when subjected to +2500 V. The tested hard disk drive could not initialize while some copper traces were melted and disconnected. This classification can be a guideline for managing manufacturing processes using essential insulators to mitigate field induced potentials in hard disk drive assembly.

An Integration Method of Resonant Switched-Capacitor Converters Based on Parasitic Inductance

The parasitic inductor can be used as resonant component to increase the power density in resonant converters. However, the parasitic inductance value of PCB copper traces is not large enough to achieve zero current switching in low and medium switching frequency conditions. To tackle this problem, a novel integration method to increase parasitic inductance value is proposed in this letter. The proposed method is based on direct coupling, which utilizes lateral structure and vertical structure to increase equivalent inductance between two parasitic inductors. The proposed method not only can achieve high efficiency, high power density, and very low profile design, but also can save the cost and space of discrete inductors for the designed prototype in low and medium frequency range. The comparison and design procedure of both lateral and vertical structures of the parasitic inductor are presented in details. Two 100-W prototypes employing gallium nitride devices are built to compare the discrete inductor solution with the proposed parasitic inductor integration method. The power density of the prototype using parasitic inductor is 62.5% higher than discrete inductance and has achieved a peak efficiency of 93.4%.

The trace elements influence on the tomato plants heat resistance in arid climate

In the arid conditions of the Astrakhan region agricultural plants heat resistance is one of the important criteria of quality production getting. In this regard, and also taking into consideration the fact that the soils of our region are characterized by a very low content of trace elements in the form accessible to plants, researches were carried out to study the effect of trace elements of copper, manganese and zinc for tomato plants heat resistance. To exclude the trace elements rapid absorption by the soil, plants foliar treatments were used during the growing season with 0.05% solutions of zinc sulfate (ZnSO4), manganese sulfate (MnSO4) and copper sulfate (CuSO4). In the control variant, the plants were sprayed with water. The results showed that tomato plants foliar feeding during the III-V organogenesis stages with 0.05% solutions of zinc sulfate, manganese sulfate and copper sulfate have not got a significant effect on tomatoes growth and productivity. However, the zinc and copper trace elements positively influenced such physiological parameters of plants as the leaf cells hydration, the bound water content in them, the protoplasm viscosity, thereby contributing to the increase in tomato resistance to the adverse effects of high temperatures in the arid climate.

Assessment of potential variability of cadmium and copper trace metals using hindcast estimates.

Trace metals are vital to primary productivity and play an essential role as main components in regulating oceanic biogeochemical cycles. Dissolved and particulate trace metals within the water column may vary due to primary production, temperature, and nutrient changes, factors that may also vary spatially and temporally. Furthermore, assessment of trace metals mainly relies on in situ observation, and so wide-area investigation of trace-metal concentration may be challenging and subject to technical constraints. A specific approach is therefore necessary that combines biogeochemical proxies, satellite data, and trace-metal linear correlation. This study aims to assess the potential spatio-temporal variability of sea surface cadmium (Cd) and copper (Cu) concentrations in Indonesian seas and surrounding areas. The correlations of Cd and Cu concentrations with primary production and nutrient data were used to convert hindcast satellite data into estimates of the metals' concentrations. The potential variability of trace metals can be determined by overlaying both data. Indonesia's Fisheries Management Areas (FMAs) were used for data clustering and analysis. The results show that Cd and Cu trace metals have similar distribution patterns throughout the year. However, dissolved Cu has a more diverse coverage area than dissolved Cd, including within the Halmahera, Seram, and Maluku Seas (FMAs 716 and 717), the Makassar Strait (FMA 717), and the Java-Sumatra upwelling area (FMA 573). Both Cd and Cu concentrations in the Java-Sumatra upwelling region follow the periodic upwelling pattern. Overall, both Cd and Cu show a declining trend in concentration from 2012 to 2019. It is estimated that dissolved Cd concentration declined from 1500-2000pmol/kg in 2012 to 1000-1500pmol/kg in 2019 for all locations. Dissolved Cu concentration decreased from 30-35nmol/kg in 2012 to 25-30nmol/kg in 2019. Estimated dissolved Cd and Cu follow the linear functions of silicate (SiO4), nitrate (NO3), and primary productivity. The fluctuation of anthropogenic activities and global warming are likely to indirectly impact the decline in metal concentrations by affecting nutrients and primary productivity.

Integrated Electromagnetic-Thermal Approach to Simulate a GaN-Based Monolithic Half-Bridge for Automotive DC-DC Converter

New technological and packaging solutions are more and more being employed for power semiconductor switches in an automotive environment, especially the SiC- and GaN-based ones. In this framework, new front-end and back-end solutions have been developed, and many more are in the design stage. New and more integrated power devices are useful to guarantee the performances in electric vehicles, in terms of thermal management, size reduction, and low power losses. In this paper, a GaN-based system in package solution is simulated to assess the structure temperature submitted to a Joule heating power loss. The monolithic package solution involves a half-bridge topology, as well as a driver logic. A novel integrated electromagnetic and thermal method, based on finite element simulations, is proposed in this work. More specifically, dynamic electric power losses of the copper interconnections are computed in the first simulation stage, by an electromagnetic model. In the second stage, the obtained losses’ geometrical map is imported in the finite element thermal simulation, and it is considered as the input. Hence, the temperature distribution of the package’s copper traces is computed. The simulation model verifies the proper design of copper traces. The obtained temperature swing avoids any thermal-related reliability bottleneck.

Direct Laser Writing of Graphene‐Based Electrical Interconnects for Printed Circuit Board Repair

AbstractMalfunctions in printed circuit boards (PCBs) are often caused by damaged copper traces. Printing materials such as metal nanoparticles, conductive polymers, and graphene along with novel printing methods are being actively explored for repairing the conductive connections in PCBs. Because of its high‐resolution capability, direct writing of conductive traces gets significant attention, especially with the widespread use of flexible PCBs. Graphene is an ideal material for such applications due to its excellent electrical and mechanical properties. However, there have been limited reports on graphene‐based methods for the facile fabrication of conductive traces. A novel method of femtosecond laser direct writing of graphene traces by the photoreduction of graphene oxide (GO) to conductive reduced GO (rGO) for repair and modification of legacy PCBs is reported. A trace‐width resolution of 28.4 μm is achieved over a large patterning area of 100 mm × 100 mm. The rGO thickness is found to be tunable from 0.6 to 4.4 μm, while the sheet resistance is minimized to 100 Ω sq−1. The system capability is demonstrated by printing conductive traces on top of a flexible substrate to form a closed path for turning on a light‐emitting diode, as well as, by repairing a commercial PCB.

Scalable Thermal Masking Technique for Postprocessing of Flexible Electronics

Flexible electronics have found a wide variety of applications, especially in biomedical engineering, where their intrinsic safety and conformability provide for configurations of sensors and actuators that can accommodate complex anatomies and movement. Current scalable techniques in the manufacture of flexible electronics are limited by the challenges of working with novel, intrinsically stretchable materials, or using cost‐intensive clean room fabrication techniques needed to create strain accommodating geometries. Recently, a technique that allows for scalable postprocessing of flexible printed circuit boards (flex PCBs) to convert them to stretchable configurations is described. Herein, a mechanism for understanding this process based on a thermal masking phenomenon is described. Thermal simulation provides an understanding of the phenomenon and various aspects of the process. Copper traces are modeled along with Kapton insulating layer on ANSYS workbench and a Gaussian waveform is introduced to simulate a laser beam. An inhouse laser cutter is used to calibrate the simulations and an accurate predictive model is used to determine working conditions, resolution, and other parameters that affect the standardized usage of this process for various thicknesses of copper and Kapton that can be produced by most mass manufacturers. This process provides a path for cost‐effective manufacture of stretchable electronics.

Determination of Iron, Zinc, Manganese and Copper Trace Elements in Traditional and Commercial Black Table Olives

Determination of Iron, Zinc, Manganese and Copper Trace Elements in Traditional and Commercial Black Table Olives