1. David Pommerenke, davidjp@mst.edu
Workshop Work shop and panel discussions: A.1 should the industry council address adequate IEC levels?
David Pommerenke,

2. Motivation
The IEC test has been used to qualify the robustness of electronic systems against ESD. The underlying discharge scenario is the discharge from a hand held metal part against a product.
The standard has been criticized and misused from different directions:
Using IEC for IC testing (a misuse)
Not having air discharge waveform or impedance specifications
Not having transient field specifications
Hard to justify voltage differences between contact and air discharge mode
Unjustified voltage statement figure A.1 in IEC  
Not considering cable discharge, or other discharge situations than the hand held metal part. For example ESD from body worn equipment to ground is not considered
Number of ESDs per test point very low, leads to large statistical uncertainty
No reality driven advice on test point selection and suggested discharges
Voltage test levels seem to be rather arbitrarily, real voltage levels can exceed 20kV
Testing of phones on the their back side leads to a test situation in which the display is facing down, this test seems unrealistic and its reproducibility is strongly affected by corona discharge and flatness of the insulator sheet
No specifications for ESD generator discharges into impedances other than a short
Oversimplified ESD generator circuit model
No guidance on given on good testing and documentation (current measurement testing, secondary ESD, video taping of testing, robotic testing)
No clarification on the effect of humidity
The Industrial council on ESD target level does not have the standard setting authority, but by creating a white paper it maybe able to create a consensus on the interpretation of the standard and it may set out a path for a revision of the standard.

3. Deficiencies of the IEC 61000-4-2
Discharge situations: Only HMM, CDE, body worn equipment discharges, etc. not considered
No consideration on how to perform testing providing the lowest test result uncertainly and best documentation e.g., measure the discharge current to observe for secondary ESD, and to document the current which caused a failure, monitor the testing using a camera to document small DUT effects, and details of the testing, test points
No specifications for air discharge, large variations between ESD generators are observed
Only short circuit current specifications
No transient field specifications
Only one waveform in contact mode to cover a wide range of real rise times
Number of discharges per point is very low
Voltage levels in reality can certainly > 20kV
ESD generators have pre-pulses, post-pulses, transient fields pulses from relay charging, leakage currents to tips, … many imperfections, each generator has a different set
Upside down display test seems unrealistic
What is missing?
Are these real issues, or only true but irrelevant observations?
All not a real issue, just an issue between OEM, IC manufacturer and system integrator?
Does the testing cover “enough” real ESD? Are field failures a problem for consumer? Automotive? Medical?

4. Deficiencies in the IEC 61000-4-2 standard
Voltage levels
Most people associate ESD with tribo-charging by walking on a carpet. However, much higher voltage levels are reached by removing a sweater in dry air, or by sitting up from a chair in dry air. Reaching 20kV is no problem in such cases:
Shall a standard (test method + levels + criteria) cover the highest possible values?
What failure rate shall a standard accept?
Which distributions should be used to estimate the failure rate?
Shall a standard also consider the failure mode (for medical equipment)?

5. Deficiencies in the IEC 61000-4-2 standard
Discharge situations The standard is based on the discharge of a small hand held piece of metal. It does not consider cable discharge or discharges which body worn equipment may face.
Waist
1kV level discharges.
Wrist
Arm
Hand held
IEC contact mode level:
3.75 A/kV
Head
Peak current
Rise time: 20%-80%
Total Charge
Total charge in ADS
Waist
20.24A
0.50ns
1.48X10-7C
1.76X10-7C
Arm
18.48A
0.53ns
1.35 X10-7 C
1.45 X10-7 C
Hand held
6.163A
0.26ns
0.94 X10-7C
1.03 X10-7C
Head
9.795A
0.70ns
1.09 X10-7C
1.36 X10-7C
Wrist
11.97A
0.42ns
0.76 X10-7C
0.98 X10-7C 5

6. Upside down configuration of a display
General setup of a phone or tablet in the display down configuration and indication of current paths
ESD Generator
HCP
470kΩ
0.5mm Insulator
DUT

7. Phone placed on the insulating layer using a spacer(30pF)
Discharge Current Measurement Using Contact Mode
Different arrangement of the cellphone:
Tilt Configuration
Phone placed on the insulating layer flat (65pF)
Phone placed on the insulating layer using a spacer(30pF)
Normalized by dividing by the kV level
First peak is linear with respect to voltage.
But other peaks not
Current of the first peak. Rather linear with voltage.
Lower for the tilted configuration, but not so different.
However, the analysis of the current waveforms shows corona

8. Using dust figures to visualize surface discharges
Surface discharges deposit charges on the insulator.
The charge distribution is related to the current that had flown on the insulator
The charge distribution can be visualized by blowing dust (laser printer toner) onto the insulator.
This method is known since 1776.
Dust figure obtained at +12kV on a cell phone display.
Diameter is 30mm

9. Corona Discharge Visualization by dust figure
Distribution of charges on the insulating layer after discharging to a phone (display down, 25kV)
Air discharge current
Surface discharges along the top surface of the insulating layer used on top of the HCP
Discharge at 25kV
Corona discharge:
Additional current at the edge of the phone
Spread multiple centimeters away

10. Corona Discharge Visualization by dust figure
Are the problems important enough such that they need to be solved?
Is the industry council the right forum?
Simulator specifications?
Test guidance for repeatable results?
Test guidance for documentation?
Safety concerns?
Unrealistic cost in complying?
Worries about being audited by authorities?
Constant conflicts about passing/failing with OEMs or other test labs?
Too many field failures?
Failure in the field from ESDs types not covered?
Misuse of the standard by IC testing increases cost?
Unrealistic test requirements lead to slow down in technology progress?
Test result uncertainly just to high to consider this a justified test?
Voltage levels too high? Or too low?
Etc.?
Can the Industry Council solve this?
Has the council and formal or practical authority?
Should a whitepaper detail the problems? Or Show solutions, or two whitepapers?
How to pass this on to authority? IEC?