Academic literature on the topic 'EMI shield layer'

High-speed digital and wireless devices radiate undesired electromagnetic noises that affect the normal operation of other devices causing electromagnetic interference (EMI) problems. Printed circuit board (PCB) and system-level shielding may alleviate inter-system EMI between the PCB board and the outside environment, but does not prevent intra-system EMI within the shielding enclosure. Package and System in Package (SiP) level shielding is often used to minimize intra-system EMI issues. An external metal lid is traditionally employed to prevent noise emission from a device, but the cost and size of this technique makes it unattractive for modern electronics. Conformal shielding is gaining momentum due to its size and height advantages. However, high cost and complexity of the sprayed coating shield prevents it from being used for a wide range of low cost commercial applications. In this paper, an innovative shielding technology with sputtered metal conformal shield is investigated using a specially designed test vehicle. By sputtering a conductive material onto a package, a very thin (typically a few μm) metal layer is constructed on the top and around four sides of the package. This thin sputtered metal layer adds virtually zero penalty to the package size. The cost and complexity of the sputtering process is significantly lower compared to a spraying process. Several types of shielded and unshielded modules were built and extensively tested for both far-field and near-field shielding effectiveness (SE) in a semi-anechoic chamber. The performance of the sputtered conformal shield is compared to that of an unshielded module and the sprayed shield. The measured results show that the sputtered shield performs equally well to a sprayed shield, in far field test, with most measurements better than 40 dB of SE. In near field testing, sputtered shields mostly outperform the sprayed shield, especially when compared in the entire scanned region. A well-designed sputtered conformal shield can, therefore, be a very cost-effective EMI solution for a wide range of packages, such as SiP. Also in the paper, a full wave 3D HFSS model is presented and simulated results for both far and near field are compared with measured data.

This study coats complex colloid mixed with Sn-xAl powders and polyethylene on glass to examine the shield effect on electromagnetic interference (EMI). In addition, the sputtering specimens and powder coating specimens were compared. The results show that adding Al to the Sn-xAl powders can increase the electromagnetic interference (EMI) shield at lower frequencies. Notably, the number of cavities in the coating layer increased with the coating thickness, with the result that the EMI shield could not improve with an increase in the coating thickness at higher frequencies. However, the EMI shield of sputtering films had a tendency to increase as the thin thickness increased. The Sn-40Al undergoes a dispersing effect which forms a fine overlapping structure, thereby improving the low frequency EMI shielding. In addition, the Sn-20Al powders possessed the properties of a small particle size, closed structure and higher electric conductivity which improved the high frequency EMI shielding. For the sputtering films, the annealed treatment not only had higher electric conductivity but also increased the high frequency EMI shielding.

A light-weight, flexible electromagnetic interference (EMI) shield was prepared by creating a layer-structured metal-polymer composite film consisting of electrospun nylon 66 nanofibers with silver films. The EMI shielding effectiveness (SE), specific SE, and absolute SE of the composite were as high as 60.6 dB, 67.9 dB cm3/g, and 6792 dB cm2/g in the X- and Ku-bands, respectively. Numerical and analytical calculations suggest that the energy of EM waves is predominantly absorbed by inter-layer multiple reflections. Because the absorbed EM energy is dissipated as heat, the thermal conductivity of absorption-dominant EMI shields is highly significant. Measured thermal conductivity of the composite was found to be 4.17 Wm−1K−1 at room temperature, which is higher than that of bulk nylon 66 by a factor of 16.7. The morphology and crystallinity of the composite were examined using scanning electron microscopy and differential scanning calorimetry, respectively. The enhancement of thermal conductivity was attributed to an increase in crystallinity of the nanofibers, which occurred during the electrospinning and subsequent hot pressing, and to the high thermal conductivity of the deposited silver films. The contribution of each fabrication process to the increase in thermal conductivity was investigated by measuring the thermal conductivity values after each fabrication process.

There are many different shielding technologies available for electromagnetic interference (EMI) shielding in radio frequency (RF) applications. We will investigate various EMI shielding technologies, one of which is RFMD's MicroShield™ Integrated RF Shielding technology's conformal plating process that encapsulates the device with a solid sheet of metal. This novel technology provides improvements in form factor, ease of use, and lower cost as compared to traditional shielding approaches. We will compare ground designs within the substrate to determine maximum EMI shield performance. An examination of ground structures, layer grounding, and external ground connections will be analyzed. The test device structure will be comprised of a radiating element on the top surface of the laminate. A thorough look at the advantages and limitations between these different EMI grounding configurations will be discussed. This data will be used to quantify grounding effectiveness which will, in turn, be used to generate design guidelines.

Abstract We studied and demonstrated high-performance Ag epoxy composites. A variety of shaped Ag particles were teste to optimize the electrical properties and mechanical reliability. The resulting Ag epoxy composites containing flake-shaped Ag particles showed less than 5×10−7Ω·m electrical conductivity and about 20mΩ series-resistance of PKG daisy chain, which directly corresponded to the excellent shield effectiveness. The shield effectiveness of resulting EMI shielding layer made of Ag and matrix is as high as 60dB, 65dB, 70dB at 5um, 10um, 20um-thick film, respectively by ASTM standard. We studied that how various factors, such as curing temperature, Ag contents, and film thickness, effects the electrical properties of shielding material and FCBGA package. It was found that the resistivity of conductive shielding material and the series-resistance were affected by the curing temperature than the curing time. Additionally, we demonstrated the electrical properties of AgCu epoxy composites.

The ELI (Extreme Light Infrastructure) Laser Centre building is a relatively complex object, which has to meet a number of unusual requirements arising from its function. A reinforced concrete structure of the laser hall is one of the most complex parts of the Centre. The structure not only fulfils its static function – withstanding the static load, but it must also minimize any incidental vibrations and shield radiation generated during operation of the laser. Structural and material solution of the structure must match these requirements.

Shielding of instruments and humans from electromagnetic interference (EMI) has become increasingly important during the last decades due to more and more machines and devices radiating electromagnetic waves. While several applications can use rigid shields, more flexibility is enabled by developing bendable, drapable, ideally even stretchable EMI shielding. Textile fabrics can have these properties, combined with potentially good mechanical properties, depending on the textile structure and the chosen material. On the other hand, the necessary physical properties, especially conductivity and magnetic properties, cannot be taken for granted in normal textile fabrics. These properties have to be added by conductive yarn or layer coatings, integration of conductive or magnetic fibers, producing intrinsically conductive or magnetic fibers, etc. The article gives a critical comparison of the properties of materials typically used for this purpose, such as intrinsically conductive polymers, metal-coated fabrics and metal wires, MXene coatings, MXene fibers, carbon coatings, and fibers. The review concentrates on thematically suitable papers found in the Web of Science and Google Scholar from the last five years and shows that especially MXenes are highly investigated recently due to their high conductivity and EMI shielding effectiveness, while other conductive and magnetic coatings and fibers are nevertheless still interesting for the preparation of EMI shielding textile fabrics.

Electromagnetic interference (EMI) shielding is a common technology used to protect electronic devices from the interference of environmental noise or to prevent the radiation of electromagnetic waves from electronic devices to the environment. In this research, the EMI shielding principle was utilized to develop a simple and cost-effective wireless corrosion-monitoring sensor. A thin metal sheet (e.g., a steel foil) similar to the material to be monitored was attached onto the surface of a radio frequency identification (RFID) transponder and served as an RF shielding layer to block the communication between the RFID transponder and the transceiver. The shielded transponder (the sensor) was then subjected to corrosion exposure, which caused the corrosion of the shielding metal sheet and led to the degradation of the shielding effectiveness. By chronically recording the change of the RF signal strength and the amount of corrosion that occurred, a correlation could be established between the signal strength and the corrosion rate. In this way, a simple wireless corrosion-monitoring sensor was developed. Steel sheets with various thicknesses (50 μm to 250 μm) were used as shielding layers on ultra-high-frequency RFID transponders, and the sensors covered by these various sheets behaved differently during corrosion exposure. The microstructure change of the shielding material was characterized by optical microscopy and scanning electron microscopy, which revealed the uneven thinning and final damage of the shielding layer, leading to the (partial) restoration of the RF signal.

A sandwich-structured natural fiber-based magnetic composite, without the use of a binder, was developed in this study. It was fabricated via in situ synthesis, densification, and magnetron sputtering processes. The chemical composition, crystal structure, microstructure, and thermal stability were characterized via X-ray photoelectron spectroscopy, energy-dispersive spectroscopy, X-ray diffraction, scanning electron microscope, and thermogravimetric analysis. The hydrophobic, magnetic, and electromagnetic interference shielding properties were investigated by measuring the static water contact angle, the magnetic hysteresis loops, and the shielding effectiveness. The resulted composites exhibited a unique inner structure with a larger iron oxide size and content (492 nm and 26.1 wt%) on the interlayer surface in comparison to the core layer (135 nm and 18.7 wt%). The magnetic response can be controlled by the loaded iron oxide content and the copper film deposition. Sputtering copper film changed the surface free energy, and created rough micro-/nanostructures, which yielded a highly hydrophobic nature (133° in water contact angle), and approximately 99.2% of the electromagnetic energy was shielded by the 0.8 mm thick composite.

The push for heterogeneous integration requires very unique material properties with respect to processing, material constants, and integration capabilities with other materials (such as copper, III–V, magnetics, etc.). Current common circuit board materials such as ceramics and laminates, as well as silicon substrates, suffer from a variety of limitations. For ceramics and laminates, these constraints include: (1) the inability to produce narrow line widths <100 m with narrow gaps between lines <100 m; (2) high surface roughness (on the order of 2μm RMS); (3) layer-to-layer misalignments; and (4) lack of high-quality integrated passives. For silicon, these constraints include: (1) high cost; (2) long design/production lead times; and (3) electrical properties of standard doped silicon are not suitable for millimeter-wave applications. A significant drawback of ceramics and laminates is that they cannot be 3D structured with micron-scale precision which is necessary for advanced interconnects for millimeter-wave IC packaging integration (e.g. transistor-to-board interconnects). These characteristics lead to devices with limited integration options, large footprints, and higher power consumption. To overcome the above limitations, 3D Glass Solutions (3DGS) has developed a photo-sensitive glass ceramics as a board-level system substrate. Compared to ceramics, laminates, and silicon, photo-sensitive glass ceramic materials offer higher interconnect densities, lower processing cost, better spatial resolution, as well as improved electrical properties for both RF and millimeter-wave frequencies. Photo-sensitive glass ceramics are ideal systems-level materials for heterogeneous integration programs as they overcome many of the limitations of legacy materials such as ceramics and laminates for broadband applications (DC – 100GHz). Furthermore, the advanced manufacturing ability of photo-sensitive glass ceramics enable a broad category of IP Blocks. The innovations of the 3DGS technology and research effort include:Low loss and low dispersion: photosensitive glass material has a measured loss tangent of 0.008 at GHz frequencies. Furthermore, the thick and highly-conductive metallization layers allow for low-loss transmission lines.High current and power handling: the metallization processes enable lines with a range of thicknesses (<50m) and widths (>2m), which result in both low resistive loss and high current handling. Additionally, the RF power handling is high due to the high breakdown voltage of glass (10kV/100m) and the possibility of coaxial line integration.Thermal management: high-density metal-filled via arrays generate up to 100W/mK thermal transfer in the 3DGS process and provide an additional thermal path for chips that are not mounted directly on a heterogeneous interface heat spreader.Built-in filtering: when a variety of chiplets with unknown design parameters and with signals of varying time constants are interconnected, EMI becomes a significant problem. The 3DGS approach allows for high-quality filtering, coupling and self-assessment functions to be directly integrated within the 2.5D interposer system as IPDs eliminating wire bonding and providing seamless integration with low loss.Scalability: the glass interconnect plane can be fabricated with footprints up to 40mm × 40mm with integrated air cavities for chip placement, through glass vias for I/Os and redistribution metal. In this presentation, 3DGS will present on three Heterogeneous Integration attributes: (1) design considerations, (2) integration of passive devices, and (3) millimeter wave integration. Design Considerations 3DGS is developing an IP Block library with 11 distinct categories. These categories include: (1) metal filled I/Os, (2) copper redistribution layers, (3) thermal management blocks, (4) cavities, (5) metal filled through glass structures, (6) phased array antenna, (7) conductor undercuts, (8) magnetic core devices, (9) capacitors, (10) inductors, and (11) grounding. While each of these unique IP Blocks contributes their own advantages for analog performance, they can all be integrated into a single chip. Integration of Passives Devices The foundation of the work done by 3DGS is on developing a volume manufacturing approach for high uniformity through glass vias (TGVs). All TGVs for I/O applications are 100% copper filled for low-loss, high power, electrical connections. Two major building blocks of 3DGS' Heterogeneous technology are High Quality Factor inductors and capacitors. 3DGS has developed a broad library of inductor components ranging from 0.5 – 200nH. Footprints are determined by inductance sizes but may be as small as 01005. Capacitors are built by placing two slots inside of the glass material, filling the slots with copper, and using the glass' natural Dk to form a capacitor. The benefit of these capacitors include high breakdown voltage (>1,000V), small footprint, high reliability, and Quality factors between 200–300. Inductors and capacitors can be integrated into a single monolithic RF package called an Integrated Passive Device (IPD). The benefits of the IPD include the elimination of RF losses associated with PCB Interconnects, long metal redistribution line lengths, bond pads, solder balls, and inconsistent assembly. This leads to the production of RF devices, capable of operating in the MHz – GHz frequency range with higher overall system Quality Factors, lower ripple, and lower losses. Furthermore, IPDs can be directly integrated into more complex System-in-Package (SiP) architectures. This approach has been used to build an RF ZigBee module in APEX® Glass [1]. The glass SiP module consisted of 35+ SMT components and was itself soldered to a PCB board. The full RF module was then subjected full complement of reliability tests and met the customer's stringent performance goals. Millimeter Wave Integration A major benefit of glass is the ability to produce low loss structures for millimeter wave applications. 3DGS has been designing and producing a variety of millimeter wave band pass filters with a variety of bandwidths ranging from 5–40%. These bandpass filters are compact, fully shielded and low loss (<2.0dB) with high attenuation (>50dB).

Extensive use of electronic devices in daily communication and information technology causes high (microwave) frequency electromagnetic interference (EMI). This EMI often leads to noise, data misinterpretation or malfunctioning of electronic devices such as medical equipment. To protect the device from this unwanted EMI, a shield layer is essential, which can shield the device from the unwanted radiation via either reflection or absorption. As the reflected microwave may cause further EMI, the later phenomenon is advantageous, because it forbids any further interference with neighboring devices. This absorption-based shielding is also useful in stealth technology to design radar camouflage military aircraft. Metallic shields normally reflect the microwave and are heavy. To address this issue one requires shield layers with lightweight and conducting. In this respect, conducting polymer-based or metallic nanoparticles based composites seems handy. Hence, in this thesis work, we have adopted various strategies to design composites that can address the above limitations of metallic shields. We have demonstrated that the scattering, reflection and absorption of microwave depend upon the micro and macroscopic properties of the filler particles. Such properties include concentration, size, morphology, conductivity, defects and magnetism of the filler materials. We have systematically investigated their effect on EMI shielding to validate our strategies. We used composites of conducting polymer (Polyaniline), hard ferrimagnetic hexaferrites, soft magnetic Yttrium Iron Garnet (YIG), metallic iron particles, metal (Fe/Co/Ni) doped carbonaceous materials along with microwave transparent paraffin wax or PVDF. The effect of concentration, size, morphology, conductivity, defects and magnetic properties of these fillers in these composites on EMI shielding is studied. Furthermore, to understand the atomistic mechanism of shielding through light-matter interactions, complex permittivity and permeability of composites used to demonstrate the dielectric and magnetic loss contributing to the microwave absorption. In this work, in particular, the mechanistic insight into the role of concentration of hexaferrite in hexaferrite-polyaniline-Wax composites, role of network structure of garnet particles in YIG-polyaniline-wax composite, the effect of size of carbon-coated iron/iron carbide particles and micron-sized iron particles in PVDF composite, the role of defects in carbon-coated cobalt and iron particles in scattering of microwave, the effect of improved graphitization and role of magnetism in carbon-coated cobalt and iron particles and the effect of morphology of bimetallic alloy doped carbonaceous materials in PVDF matrix, on EMI shielding behavior is studied in detail. It is demonstrated that using different strategies, the designed composite specimens are very highly effective in attenuating the microwave radiation. The mechanistic insight into microwave absorption in designing highly absorbing EMI shield layer is the highlight of this thesis. The results can directly utilize for industrial applications.

Nowadays, fiber based flexible electromagnetic shields have widespread applications in ensuring Electromagnetic Compatibility (EMC). Shielding is a solution of EMC, and the main methods to estimate shielding effectiveness are represented by the circuit method and the impedance method. Magnetron sputtering of metallic layers represents a novel technique to impart electric conductive properties to fabrics. Coating of fabrics represents a second main option to manufacture textile shields beside the insertion of conductive yarns in the fabric structure. Life Cycle Assessment (LCA) is often used to assess a comparatively modern with a classical manufacturing process in order to prove its eco-friendly character. This chapter comparatively assesses flexible EM shields manufactured of fabrics with inserted conductive yarns with and without magnetron plasma coating. The copper plasma coating of cotton fabrics with inserted silver yarns increases shielding effectiveness (EMSE) by 8–10 dB. In order to keep for the LCA study the same functional unit of 50 dB at 100 MHz for one sqm of fabric, the fabric structure is modeled with a reduced distance between the inserted conductive yarns. Results of the LCA study show a substantial impact on the environment for the plasma coated fabric upon using a laboratory scale deposition set-up.

Electromagnetic (EM) waves, such as electronic noise and radio frequency interference can be regarded as an invisible electronic pollution which justifies a very active quest for effective electromagnetic interference (EMI) shielding materials. Highly conductive materials of adequate thickness are the primary solutions to shield against EMI. Equipment cases and basic structure of space aircraft and launch vehicles have traditionally been made of aluminum, steel and other electrically conductive metals. However, in recent years composite materials have been used for electronic equipment manufacturing because of their lightweight, high strength, and ease of fabrication. Despite these benefits, composite materials are not as electrically conductive as traditional metals, especially in terms of electrical grounding purposes and shielding. Therefore, extra effort must be taken to resolve these shortcomings. The present work demonstrates a study on developing hybrid composites based on fiberglass with surface grown carbon nanotubes (CNTs) for EMI applications. The choice of fiberglass is primarily because it naturally possesses poor electrical conductivity, hence growing CNTs over glass fiber surface can significantly improve the conductivity. The fabrics were sputter-coated with a thin layer of SiO2 thermal barrier prior to growing of CNTs. The CNTs were grown on the surface of woven fiberglass fabrics utilizing a relatively low temperature technique. Raw fiberglass fabric, SiO2 coated fabric, and SiO2 coated fabric which was subjected to the identical heat treatment as the samples with CNTs were also prepared. Two-layers composite specimens based on different surface treated fiberglass fabrics were fabricated and their EMI shielding effectiveness (SE) was measured. The EMI SE of the hybrid CNT-fiberglass composites was shown to be 5–10 times of the reference samples. However, the tensile mechanical properties of the composites based on the different above mentioned fibers revealed significant degradation due to the elevated CNT growth temperature and the addition of coating layer and CNTs. To further probe the structure of the hybrid composites and the inter-connectivity of the CNTs from one interface to another, sets of 20-layers composites based on different surface treated fabrics were also fabricated and characterized.

Abstract With an increasing demand for lower fuel consumption of different means of transportation, the demand for lightweight construction materials is rising. In this frame, usually metallic parts can be replaced by components consisting of fiberreinforced plastics. On the other hand, the components lose their electromagnetic field (EMF) shielding properties, which are required for many applications such as housings for electrical components. This issue can be solved by applying electrically conductive foils or meshes, often by a manual process that increases the time of production and process. In this publication, the application and parameter influence of thermally sprayed electrically conductive coatings for EMFshielding applications is discussed. Laser structuring is used as a novel surface preparation process, for the subsequent thermal spray process. The influence of the used laser-parameters is discussed accordingly. The coatings are applied by the wire-arc spray with Zinc feedstock as well as the atmospheric plasma spray (APS) process with Copper feedstock. It was found that coating properties such as adhesion strength, EMF-shield strength as well as electrical properties are provided by the proposed technology.