David Pommerenke, davidjp@mst.edu Workshop Work shop and panel discussions: A.1 should the industry council address adequate IEC 6100-4-2 levels? David Pommerenke, davidjp@mst.edu

Motivation The IEC 61000-4-2 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 61000-4-2 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 61000-4-2  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.

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?

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)?

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 61000-4-2 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

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

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

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

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

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?