Advanced Materials and Design for Electromagnetic Interference Shielding

Transcription

1 Advanced Materials and Design for Electromagnetic Interference Shielding Xingcun Colin Tong f-ep) CRC Press VV^ J Taylor&. Francis Group Boca Raton London New York CRC Press is an imprint of the Taylor Sc Francis Group, an informa business

2 Preface Author xiii xv Chapter 1 Electromagnetic Interference Shielding Fundamentals and Design Guide Concepts of Electromagnetic Interference and Electromagnetic Compatibility EMI Problems and Common Concerns EMI Emissions and Controlling Methods Conducted EMI Emission Radiated EMI Emission EMC Regulations and Testing Standards The International Standard FCC Standard European Standard Military Standard EMI Shielding Principles Shielding Effects in the E-Field and H-Field Shielding Effectiveness Absorption Loss Reflection Loss Multiple Reflection Correction Factor Shielding Modeling in Practice Metallic Enclosure EMI Gasket Shield with Apertures Cavity Resonance EMC Design Guidelines and EMI Shielding Methodology Design for EMC Shielding Methods and Materials Selection Shielding Housing and Enclosures Gasketing Integral Assembly Corrosion and Material Galvanic Compatibility Environmental Compliance RoHS Directive WEEE Directive 34 References 35 v

3 Chapter 2 Characterization Methodology of EMI Shielding Materials Shielding Effectiveness Measurement Testing Methods Based on MIL-STD Modified Radiation Method for Shielding Effectiveness Testing Based on MIL-G Dual Mode Stirred Chamber Transverse Electromagnetic (ТЕМ) Cell Circular Coaxial Holder Dual Chamber Test Fixture Based on ASTM ES Transfer Impedance Methods Transfer Impedance of Coaxial Cables Transfer Impedance Method for Shielding Effectiveness Measurement of Conductive Gaskets Electrical and Thermal Conductivities Electrical Conductivity and Contact Resistance Thermal Conductivity Permeability and Permittivity Permeability Permittivity Characterization of Permeability and Permittivity Mechanical Properties Uniaxial Tensile Testing Hardness Poisson's Ratio Stress Relaxation Contact Force Friction Force Permanent Set Surface Finish and Contact Interface Compatibility Corrosion and Oxidation Protection Noble Finish Selection Nonnoble Finishes Solderability of Surface Finishes Effects of Mating Cycles and Operating Environments on Contact Finishes Galvanic Corrosion and Contact Interface Compatibility Formability and Manufacturability Bending Formability Effect of Strain Hardening on Formability Anisotropy Coefficient Springback during Metal Strip Forming Environmental Performance Evaluation Thermal Cycling Thermal Aging Gaseous Testing 63

4 vii Pore Corrosion and Fretting Corrosion Temperature and Humidity Testing Dust Sensitivity Test Vibration and Shock Test 65 References 65 Chapter 3 EMI Shielding Enclosure and Access Enclosure Design and Materials Selection Magnetic Field Shielding Enclosure Basics of Magnetic Shielding Magnetic Shielding Materials Selection Magnetic Shielding Enclosure Design Consideration Shielding Enclosure Integrity Specialized Materials Used for Shielding Enclosure EMI Gaskets Metal Strip Gaskets Knitted Metal Wire Gaskets Metal-Plated Fabric-over-Foam (FOF) Electrically Conductive Elastomer (ECE) Gaskets Magnetic Screening Materials Shielding Tapes Thermoformable Alloys Honeycomb Materials Painted or Plated Plastic Enclosures Conductive Composite Shielding Materials Summary 86 References 87 Chapter 4 Metal-Formed EMI Gaskets and Connectors Introduction Metal Strip Selection and Performance Requirement Copper Beryllium Alloys Phase Constitution and Primary Processing of CuBe Strips Performance and Availability of CuBe Alloys High-Strength Alloys High-Conductivity CuBe Alloys Nickel Beryllium Copper-Nickel-Tin Spinodal Alloys Composition and Physical Properties Strip Gauges and Temper Designations Mechanical Properties and Bending Formability Stress-Relaxation Resistance Heat Treatment and Spinodal Decomposition Surface Cleaning, Plating, and Soldering 103

5 viii Contents Elastic Performance Shielding Effectiveness Fatigue Strength Some Considerations to Improve Performance of CuNiSn Gasketing Copper-Titanium Alloy Stainless Steel Other Materials Options Phosphor Bronze Brass Ill Nickel Silver Ill Other High Strength and High Conductive Copper Alloys Design Guideline of Metal Gaskets and Connectors Primary Approaches Some Special Design Options Gasketing Design Guideline Fabrication Process and Types of Metal Gaskets and Connectors Progressive Die Forming Roll Forming Multiple-Slide Stamping Photoetching Typical Part Profiles Mounting Methods and Surface Mating Assurance Summary 124 References : 124 Chapter 5 Conductive Elastomer and Flexible Graphite Gaskets Introduction Raw Material Selection and Conductive Elastomer Fabrication Base Binder Materials Silicone Fluorosilicone Ethylene Propylene Diene Monomer (EPDM) Fluorocarbon Natural Rubber and Butadiene-Acrylonitrile Conductive Fillers Fabrication of Conductive Elastomer Materials Conduction Mechanism and Processing Optimization of Conductive Elastomer Materials Conduction Mechanism and Process Parameters Appearance Properties and Performance Evaluation Physical and Mechanical Properties Electrical Properties Thermal Properties Conductive Elastomer Gasket Design Guideline Flange Joint Geometry and Unevenness 138

6 ix Applied Clamping/Compressive Force and Deformation Range Gasket Profile and Materials Selection Flange Materials and Joint Surface Treatment Conductive Elastomer Gasket Fabrication Extrusion Molding Form-in-Place and Screen Printing Reinforced Shielding Gaskets with Oriented Wires and Metal Meshes Conductive Elastomer Gasket Installation and Application Comparable Flexible Graphite Gaskets Flexible Graphite and Its Properties Fabrication and Application of Flexible Graphite Gaskets Summary 157 References 157 Chapter 6 Conductive Foam and Ventilation Structure Introduction Waveguide Aperture and Ventilation Panel Waveguide Aperture and Its Design Materials Selection and Fabrication Options Conductive Foam and Integral Window Structure Conductive Plastic Foam and Vent Panels Integral EMI Window Structure Metallized Fabrics and Fabric-over-Foam Metallized Fabrics Fabric-over-Foam Summary 175 References 175 Chapter 7 Board-Level Shielding Materials and Components Introduction Board-Level Shielding Design and Materials Selection Basic Principles of Board Circuit EMC Design PCB Layout Power Decoupling Trace Separation Grounding Techniques Chassis Construction and Cabling Board-Level Shielding Design with Proper Materials Selection Board-Level Shielding Components and Their Manufacturing Technology 185

7 7.3.1 Metal Cans Single-Piece Shielding Cans Two-Piece Cans Multilevel Shielding and Multicompartment Cans Metal-Coated Thermoform Shields snapshot Shield Form/Met Shield Formable Shielding Film Conductive Coating Methods Used for EMI Shielding Components Electroplating Electroless Plating Electrolytic Plating Tin Plating and Tin Whisker Growth in EMI Shielding Systems Immersion Surface Finishes Conductive Paints Vapor Deposition Conductive Coating Application and Design Consideration for EMI Shielding Board-Level Shielding with Enhanced Heat Dissipating Minimizing EMI from Heat Sinks Combination of Board-Level Shielding and Heat Dissipation Thermal Interface Materials (TIMs) for Thermal-Enhanced Board-Level Shielding Summary 211 References 212 Chapter 8 Composite Materials and Hybrid Structures for EMI Shielding Introduction Knitted Wire/Elastomer Gaskets Fabrication Process and Materials Selection Knitted Wire Gasket Performance Typical Gasket Types and Mounting Methods EMI Shielding Tapes Conductive Fiber/Whisker Reinforced Composites Materials Selection and Process of Conductive Composites Carbon Fiber/Whisker Reinforced Materials Metal Fiber/Whisker Reinforced Composites Nanofiber Reinforced Polymer Composites Hybrid Flexible Structures for EMI Shielding Electroless Metal Deposition for Reinforcements of Composite Shielding Materials 231

8 xi 8.7 Summary 234 References 234 Chapter 9 Absorber Materials Introduction Microwave Absorber Materials : Resonant Absorbers Dallenbach Tuned Layer Absorbers Salisbury Screens Jaumann Layers Graded Dielectric Absorbers: Impedance Matching Pyramidal Absorbers Tapered Loading Absorbers Matching Layer Absorbers Cavity Damping Absorbers Anechoic Chambers Antennas Absorber Materials Used in Anechoic Chambers Dielectric Materials for Absorber Applications Electromagnetic Wave Absorbers Absorbing Materials Selection and Absorber Applications Absorbing Materials and Absorber Types Applications Military Commercial Summary 253 References 254 Chapter 10 Grounding and Cable-Level Shielding Materials Introduction Cable Assembly and Its EMI Shielding Design Cable-Level Shielding Materials Metallic Shielding Conductive Heat-Shrinkable Shielding Ferrite Shielding Materials Bonding and Grounding Bonding Grounding Shields Grounded at One Point Multigrounded Shields Hybrid Grounding Summary 271 References 272

9 xii Contents Chapter 11 Special Shielding Materials in Aerospace and Nuclear Industries Introduction Lightweight Shielding Materials for Aerospace Applications Lightweight Radiation Shielding Material Fiber Reinforced Composite Materials Nanomaterials Foam Structures Radiation Shielding for Space Power Systems Neutron Shielding Design and Materials Selection Shielding Materials for Earth Neighborhood Infrastructure Active Electromagnetic Shielding for Space Radiation Optimization of Space Radiation Shielding Nuclear Shielding Materials Summary 289 References 291 Chapter 12 Perspectives and Future Trends Introduction Early Design-in for EMC and Optimal Design of EMI Shielding Advanced Materials Selection for EMI Shielding Materials Selection for EMI Shielding Enclosure/Cover/ Barrier EMI Gasketing Material Selection Other Shielding Materials Selection Future Trends and Applications EMI Shielding Design Techniques Integrated Circuit-Level Shielding Printed Circuit Board (PCB)-Level Shielding Lightweight Shields for PCB-Level Shielding Mold-in-Place Combination Gaskets for Multicompartment Shields Rotary Form-in-Place Gaskets EMI Shielding Modules or Enclosures Conductive Foam with Z-Axis Conductivity Dent-Resistant Vent Panels Nanocomposite Shielding Materials Ultrasoft Sculpted Fabric-over-Foam Interconnecting Level Shielding EMI Control or Immunity by Software Summary 311 References Index 315