TR NWT 000870 : ISSUE 1
Current
The latest, up-to-date edition.
01-12-2013
1 INTRODUCTION
1.1 Scope
1.2 Document Organization
1.3 Reason for Issue
1.4 Requirements Terminology
2 ESD TUTORIAL
2.1 The Origin of ESD
2.1.1 Electric Charge in Conductors and Insulators
2.1.1.1 Electric Fields and Potentials Versus Charge
2.1.1.2 Electrical Resistivity of Materials
2.1.1.3 Electrical Capacitance
2.1.2 Charging of Materials
2.1.2.1 Triboelectric Charging
2.1.2.2 Induction Charging
2.1.2.3 Spray Charging
2.1.2.4 Ion Beam Charging
2.1.2.5 Other Charging Mechanisms
2.1.2.6 Humidity Effects
2.1.3 Discharging of Materials
2.2 The Effects of ESD
2.2.1 The Types of ESD
2.2.1.1 The Human Body Model
2.2.1.2 The Charged Device Model
2.2.1.3 The Field Induced Model
2.2.1.4 Electrical Overstress
2.2.2 The Electrical Parameters of ESD Stress
2.2.3 ESD Failure Mechanisms
2.3 Sources of ESD
2.3.1 Human-Related Sources
2.3.1.1 Clothing
2.3.1.2 Furniture
2.3.1.3 Floors
2.3.2 Packaging
2.3.3 Tools
2.3.4 Manufacturing Equipment and Processes
2.3.4.1 Taping
2.3.4.2 Curing in Airflow Ovens
2.3.4.3 Freezing Sprays
2.3.4.4 Degreasing or Defluxing Operations
2.3.4.5 Ultraviolet Light Inspection Areas
2.3.4.6 Sandblasting
3 PRACTICAL ASPECTS OF ESD PREVENTION
3.1 ESD Retardant Materials
3.1.1 General Requirements for Packaging
3.1.1.1 Protection from Physical Damage
3.1.1.2 Protection from Triboelectric Charge Generation
3.1.1.3 Protection from Direct ESD Events
3.1.2 Other Materials Properties
3.1.2.1 Cleanability
3.1.2.2 Resistance to Sloughing
3.1.2.3 Solderability/Contact Reliability
3.1.3 Packaging Material Classifications
3.1.3.1 Conductive and Shielding Materials
3.1.3.2 Dissipative Materials
3.1.3.3 Insulative Materials
3.1.4 Packages for Sensitive Components
3.1.4.1 Protective Bags
3.1.4.2 IC Shipping Tubes
3.2 Personnel Grounding
3.2.1 Wrist Straps
3.2.2 Conductive Flooring
3.2.2.1 Topical Floor Treatments
3.2.2.2 Mats
3.2.2.3 Static Retardant Flooring
3.2.2.4 Shoes and Heel Straps
3.2.3 Static Retardant Clothing
3.3 Automatic Device Handlers
3.4 Ion Generators
4 DEVICE CLASSIFICATION AND TEST METHODS
4.1 ESD Sensitivity Classifications
4.2 Determination of Human Body Model ESD Failure
Thresholds
4.2.1 Use of Private or Public Databases
4.2.2 Use of Component Vendor Data
4.2.3 Experimental ESD Threshold Measurement
4.2.3.1 Required Equipment
4.2.3.2 Waveform Verification Procedure
4.2.3.3 Classification Testing
4.3 Charge Device Model Thresholds
5 TEST METHODS FOR EVALUATION OF ESD PREVENTION
PROGRAMS
5.1 Measuring Charge Levels
5.1.1 IC Shipping Tubes
5.1.2 Sheet Materials
5.1.3 Bags and Pouches
5.1.4 Miscellaneous Packaging
5.2 Measuring Voltage Levels
5.3 Measuring Resistivity Properties
5.3.1 Sheet Resistance
5.3.2 Decay Properties
5.3.3 Buried Shielding Layers
6 ESD GENERIC REQUIREMENTS
6.1 Sensitivity Areas within the Manufacturing
Facility
6.2 Failure Threshold Determination
6.3 Limits for Electrostatic Potential
6.4 Grounding
6.4.1 Personnel
6.4.1.1 Wrist Straps
6.4.1.2 Conductive Floors/Heel Straps
6.4.1.3 Static Retardant Garments
6.4.2 Equipment
6.5 Packaging
6.5.1 Materials
6.5.2 Physical Design
6.5.3 Facility/Packaging Audits
6.5.4 Limits on Packaging Charge
6.6 Tote Boxes
6.7 Table Tops
6.8 Ion Generators
6.8.1 Decay Time Specification
6.8.2 Ionizer System Measurement and Calibration
Specifications
6.9 Summary of Required Preventive Measures
7 CONDUCTION OF ESD AUDITS AT VENDOR PLANT
8 GLOSSARY
8.1 Acronyms
8.2 Definition of Terms
9 REFERENCES
LIST OF 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
LIST OF 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
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