Electrostatic Discharge Control in the Manufacture of Telecommunications Equipment

Transcription

1 Electrostatic Discharge Control in the Manufacture of Telecommunications Equipment 1. INTRODUCTION Scope Document Organization Reason for Issue Requirements Terminology ESD TUTORIAL The Origin of ESD Electric Charge in Conductors and Insulators Electric Fields and Potentials Versus Charge Electrical Resistivity of Materials Electrical Capacitance Charging of Materials Triboelectric Charging Induction Charging Spray Charging Ion Beam Charging Other Charging Mechanisms Humidity Effects Discharging of Materials The Effects of ESD The Types of ESD The Human Body Model The Charged Device Model The Field Induced Model Electrical Overstress The Electrical Parameters of ESD Stress ESD Failure Mechanisms Sources of ESD Human-Related Sources Clothing Furniture Floors Packaging Tools Manufacturing Equipment and Processes ix

2 TR NWT Taping Curing in Airflow Ovens Freezing Sprays Degreasing or Defluxing Operations Ultraviolet Light Inspection Areas Sandblasting PRACTICAL ASPECTS OF ESD PREVENTION ESD Retardant Materials General Requirements for Packaging Protection from Physical Damage Protection from Triboelectric Charge Generation Protection from Direct ESD Events Other Materials Properties Cleanability Resistance to Sloughing Solderability/Contact Reliability Packaging Material Classifications Conductive and Shielding Materials Dissipative Materials Insulative Materials Packages for Sensitive Components Protective Bags IC Shipping Tubes Personnel Grounding Wrist Straps Conductive Flooring Topical Floor Treatments Mats Static Retardant Flooring Shoes and Heel Straps Static Retardant Clothing Automatic Device Handlers Ion Generators DEVICE CLASSIFICATION AND TEST METHODS ESD Sensitivity Classifications Determination of Human Body Model ESD Failure Thresholds Use of Private or Public Databases Use of Component Vendor Data Experimental ESD Threshold Measurement Required Equipment Waveform Verification Procedure Classification Testing Charged Device Model Thresholds x

3 5. TEST METHODS FOR EVALUATION OF ESD PREVENTION PROGRAMS Measuring Charge Levels IC Shipping Tubes Sheet Materials Bags and Pouches Miscellaneous Packaging Measuring Voltage Levels Measuring Resistivity Properties Sheet Resistance Decay Properties Buried Shielding Layers ESD GENERIC REQUIREMENTS Sensitivity Areas within the Manufacturing Facility Failure Threshold Determination Limits for Electrostatic Potential Grounding Personnel Wrist Straps Conductive Floors/Heel Straps Static Retardant Garments Equipment Packaging Materials Physical Design Facility/Packaging Audits Limits on Packaging Charge Tote Boxes Table Tops Ion Generators Decay Time Specification Ionizer System Measurement and Calibration Specifications Summary of Required Preventive Measures CONDUCTION OF ESD AUDITS AT VENDOR PLANT GLOSSARY Acronyms Definition of Terms REFERENCES xi

4 TR NWT xii

5 List of Figures List of Figures Figures Figure 2-1. Drawing of the Faraday Cup Figure 2-2. Charging of a Conductor by Induction Figure 2-3. The Ideal HBM ESD Waveform at 1500-V Stress Figure 2-4. Schematic Circuit Diagram of Standard HBM ESD Simulator Figure 2-5. Schematic Drawing of CDM ESD Simulator Figure 2-6. CDM ESD Stress Waveform Figure 2-7. CDM, HBM, and EOS Stressing Waveforms xiii

6 TR NWT List of Figures xiv

7 List of Tables List of Tables Tables Table 2-1. Triboelectric Series Table 2-2. Typical Electrostatic Voltages Table 2-3. ESD versus EOS Stressing Parameters Table 3-1. Classifications of Packaging Materials Table 4-1. ESD Sensitivity Classifications Table 4-2. Stress Current Waveform Specifications Table 4-3. Stressing Pin Combinations Table 6-1. Required ESD Preventive Measurements xv