1. 3
Static
Awareness
Seminar

2. Types of ESD Failures to Electronic Devices
Catastrophic Failure
Device no longer operates
Represents 10% of ESD failures
Intermittent / Walking Wounded
Device is operational, but erratic and will cause additional service calls
Represents 90% of ESD failures

3. Static Damaged Mos Transistor
OXIDE LAYER
GATE
DRAIN
SOURCE

4. Cost of ESD damage increases by ten (10) fold at every process level
Field Service Level
System Level
Board Level
$5000
Component Level
$500
$50 $5

5. Where do you need static protection ?
Incoming inspection and test
Stores and storage
Transfer carts
Kitting
Manual and automated insertion
Wave soldering
Equipment assembly and test
Packaging and shipping
Repair stations
Field service

6. DEFINITION OF STATIC ELECTRICITY
The electrification of materials through physical contact and separation, and the various effects that result from the positive and negative charges so formed. + + + + + + + _ _ _ _ _ _ _

7. MAJOR PROBLEMS CAUSED BY STATIC
Dust and Lint Attraction
Material Handling Problems
Damage to Products
Product Malfunction
Fire and Explosion Hazards
Shock to Personnel

8. Ranking of Semiconductor Failure Causes
EOS/ESD is the #1 Cause of
Semiconductor Failure
EOS/ESD 59%
Electrical testing 3%
Oxide/passivation
failure 3%
Conductor failure 3%
Die fracture 4%
Lead short/open 7%
Wire bonds 15%
Others 6%
Source : Semiconductor Reliability News, March 1993

9. SEMICONDUCTOR DEVICE SENSITIVITIES
Device Type
MOSFET
VMOS
NMOS
GaAsFET
EPROM
CMOS
JFET
SAW
Op-AMP
Schottky Diodes
Film Resistors
Bipolar Resistors
ECL
SCR
SChottky TTL
Threshold Susceptivity (Volts)
100+
500+

10. HUMAN PERCEPTIONS OF ESD
At 3000 volts, you can ESD
At 5000 volts, you can ESD
At volts, you can ESD

11. ELECTROSTATIC VOLTAGES
Typical Electrostatic Voltages
ELECTROSTATIC VOLTAGES
MEANS OF
STATIC GENERATION
10 TO 20 PERCENT
RELATIVE HUMIDITY
65 TO 90 PERCENT
RELATIVE HUMIDITY
WALKING ACROSS CARPET
WALKING OVER VINYL FLOOR
WORKER AT BENCH
VINYL ENVELOPES FOR WORK
INSTRUCTIONS
COMMON POLY BAG PICKED UP
FROM BENCH
WORK CHAIR PADDED WITH
POLYURETHANE FOAM
35,000
12,000
6,000
7,000
20,000
18,000
1,500
250
100
600
1,200
OWEN J. McATEER
MILITARY ELECTRONICS/COUNTERMEASURES

12. ELECTROSTATIC DISCHARGE (ESD)
Billions of Dollars $$$ are wasted each year because of ESD damage.
Millions of dollars in PC Board float is the result of ESD damage.

13. DAMAGE MODES Catastrophic Failure Device no longer operates
Are mostly caught in-house
Represents 10% of ESD failures
Intermittent / Walking Wounded
Device is operational, but erratic and will cause additional service calls
Most expensive static problem
Represents 90% of ESD failures

14. DAMAGES CAUSED BY ESD

15. PROPERTIES OF STATIC ELECTRICITY
A charged surface has electrical potential energy (voltage)
A charged surface emanates an electric field
A charged surface can produce kinetic energy (current)

16. STATIC CHARGE GENERATORS
Work surfaces
Floors
Chairs
Clothing
Papers and work order holders
Packaging materials
PERSONNEL

17. DEVICE FAILURE CAN HAPPEN AT ANY LEVEL
Single device
Circuit board
Product assembly
Field service

18. STATIC GENERATION Triboelectric charging Induction
Changes in capacitance

19. TRIBOELECTRIFICATION
Static Charge can be generated by contact and separation of dissimilar surfaces.
Static Charge on contacting surfaces can be increased with addition of friction or rubbing.

20. INDUCTION
Process of separating charges on a material through space at a distance by the influence of an electric field.
A conductor in the presence of an electric field can acquire a charge and hold it.
Non-conductors are polarized and able to be attracted to charged surfaces (like dust to a TV screen).

21. CHANGES IN CAPACITANCE
Voltage on an object is greatly affected by the capacitance of the object.
Capacitance can change in the environment due to position of the object relative to other objects in the area.
Increase capacitance, reduces voltage.
Decrease capacitance, increases voltage.

22. MATERIALS CHARACTERISTICS
Conductors
Allow the flow of electrons
Non-conductors or Insulators
Resist the flow of electrons

23. FACTORS AFFECTING STATIC CHARGE GENERATION
Intimacy of contact
Speed of separation
Conductivity of materials
Position on Triboelectric series

24. MATERIALS Increasing Positive Increasing Negative Steel Wood Amber
Air
Asbestos
Glass
Mica
Human Hair
Nylon
Wool
Fur
Lead
Silk
Aluminum
Paper
Cotton
Steel
Wood
Amber
Hard Rubber
Brass Silver
Sulfur
Polyester
Polyurethane
Polyethylene
Polypropylene
PVC
Teflon
Increasing Negative

25. HOW STATIC IS GENERATED+ + + + + + + _ _ _ _ _ _ _
Contact and Separation of Materials

26. STATIC FIELD EMANATES FROM CHARGED OBJECT
5,000 Volts
2,000V
3,000V
4,000V

27. Fundamentals of Static
VOLTAGES associated with static charges can be created by :
1. Triboelectric charging
2. Induction
3. Changes in capacitance
SCIENTIFIC BASIS :
1. Coulomb’s Law
like charges repel
opposite charges attract
2. V = Q/C
V = voltage in volts
Q = charge in coulomb
C = capacitance in farads

28. Typical Voltage Variations Monitored on a Person with No Wrist Strap
Feet
Raised
1550
v(max)
Operator
Sat Down
Operator
Stands Up
Operator
Sat Down
Operator
Walking
Feet
Lowered
1400 v(max)
1500
Voltage
Pulse
Height
850 v(max)
1000
3200 v/sec
5000
v/sec
500
3800 v/sec
Time

29. SOLUTIONS TO STATIC PROBLEMS
Prevention of Charge Generation
Neutralization of Charge
Dissipation of Charge
Shielding

30. PREVENTION Static cannot be totally prevented ..........
Only Limited !!!!!

31. PREVENTION
The property of Antistaticity is related to Prevention of static charge generation -
Providing surface lubricity and slightly conducting properties usually results in low charging properties.

32. DISSIPATION Removal of Charge from Conductors
Rate of dissipation controlled by resistance to ground
Slow rate of dissipation preferred by most

33. DISSIPATION
Device damage models have helped determine the need for dissipative worksurfaces.
Human Body Model
Charged Device Model
Machine Model

34. Human Body Model _ _ _ _ _ _ static discharge _ _ _ _ _ _ _ _ _ _ _ _
oxide layer _ _ _ _ _ _
static discharge _ _ _ _ _ _ _ _ _ _ _ _ _ _

35. Charged Device Model _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ discharge _ _
tweezers _ _ _ _ _ _ _
discharge _ _ _ _ _ _

36. DISSIPATION
Dissipation is the most important control property in electrostatics.
Dissipation includes grounding of people, worksurfaces and flooring.
Electrical system ground preferred over a separate system or building ground.

37. IONIZATION Creation of free charge in gases (usually air).
Coulombs Law dictates that opposite charges attract.
Ionization cancels out static charges, one for one on surfaces.
Ionization must be balanced, otherwise a charge can be added to a surface.

38. SHIELDING
Shielding is used to protect electrostatic susceptible items when they are being transported between Static Protected Areas.
Shielding is a requirement for most classes of components in Military and commercial specifications.

39. 4 RULES OF STATIC CONTROL
Handle all static sensitive items at a static safeguarded work station.
Transport all static sensitive items in static protective containers.
Test and monitor the static control process.
Make sure every party in the supply chain follows then above 3 rules.

40. RULE 1 - STATIC SAFEGUARDED WORK AREA
Provides bonding and grounding for all conductors used in the area, including people.
Provides neutralization of charge on the necessary non-conductors used in the area.

41. RULE 1 - SOLUTIONS Worksurface Materials Flooring Materials
Wrist Straps
Shoe Grounding
Ionization

42. OHM’S LAW = AMPS = VOLTS OHMS 120 MICROAMPS EXAMPLE: 120 VOLTS

43. RULE 2 - TRANSPORTATION
Products must be protected when they are moved from the static safeguarded work station.

44. RULE 2 - SOLUTIONS Flexible packaging - shielding bags
Rigid containers - tote boxes, trays, card carriers

45. RULE 3 - TEST EQUIPMENT Tester for Wrist/Shoe Strap.
“Megger” (high voltage meter) for worksurfaces and flooring.
“Charge Plate” for Ionization.

46. RULE 4
Make sure everyone that is in the supply and distribution system follows the first 3 Rules.
Conduct audits on suppliers for conformance to Operating Procedures if necessary.

47. STANDARDIZATION IN STATIC CONTROL
Standards setting organization exist in the US, Europe, and Internationally.
The most active organizations are : ESD Association, EIA, JEDEC.
The US Military also has many standards related to Static Electricity.

48. ESD ASSOCIATION TEST METHODS
Individual Products
Wrist straps, flooring, table mats etc.
Measurement Techniques
Resistance, Shielding, Charge Generation
Advisories
Guidelines, Practices, Procedures, Definitions

49. EIA - Electronic Industry Association
Packaging of Electronic Products for Shipment - EIA 541
Specifications for materials used in packaging materials
ESD Standard 625

50. PREREQUISITES FOR A SUCCESSFUL STATIC CONTROL PROGRAM
A full commitment on the part of top management
ESD control compliance on all suppliers
A comprehensive in-house ESD control program
Advise your customers on proper handling
Select a professional and knowledgeable static control vendor

51. Benefits of a total static control program
Reduced IC and PC board rejects
Reduced field service calls
More competitive service contract due to lower warranty costs
Reduced circuit board float resulting from increased IC and PC board reliability
$$ Savings proportion example:
5 PC boards in inventory per 1 PC board in the field can be reduced to:
3 PC boards in inventory per 1 PC board in the field
Reduced physical space requirements for PC
Savings = return on investment capital invested
Improved customer satisfaction (goodwill) and assure customer re-orders.
Increase share of marketplace with high quality and reliable products
Improve profits