IEC 6100-4-2 Ed.3 (Third Edition) is an international standard for electrostatic discharge immunity testing, with the latest version released in 2025. The main updates include:

Calibration requirements for testing equipment

• New calibration requirement for air discharge mode, only measuring the maximum open circuit voltage when replacing the discharge metal conductor

• The calibration of the electrostatic gun requires the addition of a 1.2 × 1.5m grounding reference panel and the adjustment of the current target height to 1m

Optimization of experimental configuration

• The distance between discharge return cables is shortened to 0.1m, and the grounding impedance requirement is ≤ 0.1 Ω

• The maximum length of the discharge cable for desktop equipment is adjusted to 1.5m, and the equipment and the horizontal coupling plate need to be separated by 0.5 ± 0.05mm insulation material

Add new testing specifications

• Adding testing methods for wearable devices, it is recommended to use a 200pF capacitor and a 50 Ω resistor

• Refine performance classification standards to allow for automatic recovery of equipment after brief failures

Adjustment of current waveform parameters

• Adjust the peak contact discharge current from 3.75A/kV to a higher precision measurement point (such as the allowable error of Ip2 peak within 10ns~40ns ± 40%)

• This standard is applicable to various electronic devices, and the testing level should be selected according to the device usage environment (industrial equipment is usually ≥ 4 levels), with priority given to using contact discharge mode

Test Method

The testing of IEC61000-4-2 can be roughly divided into two types: "direct discharge" and "indirect discharge". When obtaining standard certification, both direct discharge and indirect discharge must be carried out simultaneously.

Direct discharge is an experimental method that assumes direct contact between humans and the test device. In other words, when charged humans come into contact with electronic devices, charge transfer occurs. This test method determines whether electronic circuits will malfunction by the electromagnetic field generated during charge transfer.

The real electrostatic discharge phenomenon that occurs in direct discharge is the insulation breakdown that occurs when humans and the test device gradually approach each other from a separated position, and the electric charge carried by the human body discharges towards the test device. However, the direct discharge test method specified in IEC61000-4-2 adopts a method called contact discharge, which involves the discharge head of the discharge gun coming into contact with the application point and closing the discharge switch, injecting electrostatic current. This is a deliberate use of a method different from the phenomenon of electrostatic discharge in reality, with the aim of improving the reproducibility of the experiment.

In addition, an experimental method based on actual electrostatic discharge phenomena was adopted, which is the air discharge method that causes insulation breakdown and discharge in the air. This air discharge method is a test method in which the discharge gun is placed close to the application point until it comes into contact with the discharge switch when it is turned off.

Indirect discharge refers to the electromagnetic field effect generated by simulating the discharge of electric charges carried by the human body through fingertips or other objects near the test device.

1. When conducting direct discharge

Direct discharge includes both contact discharge and air discharge, and contact discharge is required in the metal part of the test device. Contact discharge is a method of applying electrostatic noise by turning off the discharge switch when the discharge gun comes into contact with the application point of the test device, using a conical discharge head to ensure good contact.

If there is no metal part in the test device, or if there is a metal part but the insulation surface that the user may frequently come into contact with, the discharge gun should be placed close to the application point with the discharge switch turned off until it comes into contact, in order to perform air discharge.

Circular discharge heads are used for air discharge. Compared to conical shapes, the advantage of circular shapes is that charged charges are not easily released into the air. In addition, discharge should be carried out within 5 seconds to avoid charge release.

(1) Determine the application point and discharge method

If the application point and discharge method have been determined in the test specifications, there is no need to conduct preliminary tests. Before conducting the experiment, please refer to their respective specifications. If there is no description, please perform the following actions.

(a) Determine the application point (preliminary test)

The preliminary experiment is conducted to determine which parts of the test device are susceptible to noise interference. This is the reference basis for determining which parts to apply.

The preliminary test will be conducted in the order of air discharge, contact discharge, and indirect discharge using horizontal and vertical coupling plates.

Due to the fact that the rise time of discharge current in air varies with the applied voltage, resulting in different frequency spectra, it is necessary to gradually increase the applied voltage for preliminary testing.

Contact discharge is recorded using a frequency of 20Hz (with a repetition period of 0.05 seconds) as an example. If no interval time is specified, it can also be applied once per second.

Set the mode of the ESD generator to continuous and move the discharge gun over the surface of the test device.

Set the location susceptible to electrostatic discharge as the application point.

Discharge may cause the device to become charged, making it impossible to trigger subsequent discharges properly. At this time, please use electric brushes to remove electricity and release the charge.

[Attention]

Due to the possibility of misoperation during the release of the charged sample (de electrification), de electrification through resistors (ranging from several k Ω to several M Ω) can prevent misoperation. (Refer to "3.3.3 Test Methods for Non Grounded Test Devices".) It can also be automatically de energized by combining with relays or other components (such as automatic de energization probes 01-00013b).

（b） 免施加部位

If there are no special regulations in the product specifications, the following parts are designated as discharge free parts.

1) Parts that are only in contact during maintenance

Although it is a part that users will come into contact with, the frequency of contact is very low, such as parts related to battery replacement.

2) Parts that will not come into contact after installation

For example, the bottom of desktop or floor standing devices, the wall mounted side of wall mounted devices, and the fixed connector section after installation.

3) Connector 1

When pasting warning labels near high-frequency connectors for measurement/communication that are easily affected by noise.

4) Connector 2

According to the different combinations of shell/cover materials, the location for applying electrostatic discharge is specified as follows. If the outer cover is used to protect the pins, a warning label indicating this will be affixed to or near the outer cover. The purpose of doing this is to alleviate the discharge applied to the signal pins. If the casing is made of metal, it can be expected that discharge will preferentially occur on the casing rather than the pins.

(c) Determine whether each application point is a contact discharge or an air discharge

Contact discharge is the main method, and if it cannot be achieved, air discharge is carried out. To determine whether it is contact discharge or air discharge, please refer to the following text.

contact discharge

In normal use, contact discharge is carried out to determine the metal parts that will come into direct contact with the human body.

air discharge

In normal use, air discharge is carried out on the insulation part that will come into direct contact with the human body. Usually, if there is metal present, only contact discharge is required on the metal part, but if there is an insulation part that users frequently come into contact with during normal use, air discharge is required on that part.

(2) When conducting contact discharge

When conducting contact discharge, please refer to the following content to determine the application point and discharge.

1) If there are no special issues with the preliminary test results, it is recommended to set one application point with a palm sized area.

2) Discharge metal parts that may come into contact with the human body, such as the operating section.

3) If there are multiple units, each unit needs to be discharged separately.

4) For input and output terminals, some product group standards already have relevant regulations.

5) If there is a coating on the surface, use a conical discharge head to penetrate the coating layer for contact discharge.

(Except for areas designated by the manufacturer as insulation coatings.)

6) If the test device is battery driven or not grounded, please also refer to "3.3.3 Test Methods for Non Grounded Test Devices". The location for contact discharge is indicated by the arrow in the following figure.

Perform contact discharge on the set or specified application point.

Use a conical discharge head.

Set the tester to contact discharge mode, place the discharge gun vertically against the application point, and then press the trigger switch.

Please refer to "2 Laboratory Preparation" for the test voltage level.

For each application point, at least 10 single discharges should be applied for each polarity. Suggest applying with an interval of at least 1 second.

Please keep the discharge return cable at a distance of at least 0.1m from the test device.

During the experiment, do not touch objects other than the discharge gun.

In principle, the application direction should be perpendicular to the test surface. However, when applied on the side of a thin chassis, due to the close contact between the horizontal coupling plate and the discharge gun, it is recommended to tilt it at a 45 ° angle (which does not comply with standard regulations).

[Commentary]

In the experiment of desktop devices, the test device is easily affected by the surrounding conductors. As a conductor, the human body naturally has an impact, so if discharge is applied while observing, it will affect the reproducibility of the test results. Moreover, devices with weaker noise resistance are more affected.

Regarding the grip method of the discharge gun

When holding the discharge gun for testing, the following points should be noted.

Do not touch parts outside the grip.

When holding the discharge gun with both hands or touching other parts, the human body will form parasitic capacitance in the discharge circuit, which will affect the discharge waveform and cause differences in the test results.

(3) When conducting air discharge

When conducting air discharge, please refer to the following content to determine the application point and discharge.

1) Discharge should be carried out on non-metallic operating parts and other parts that may come into contact with the human body, especially those that may discharge through resin gaps such as internal frames.

2) If there are no special issues with the preliminary test results, it is recommended to determine one application point in units of palm size for areas outside the operating section.

3) If there are multiple units, each unit needs to be discharged separately.

4) IEC61000-4-2 does not specify input and output terminals, but some product group standards have relevant provisions in reference. It is still necessary to evaluate the product.

5) If the test device is battery driven or not grounded, please also refer to "3.3.3 Test Methods for Non Grounded Test Devices". The location for air discharge is indicated by the arrow in the following figure.

Perform air discharge on the set or specified application point.

Use a circular discharge head.

The usage method of the discharge gun is as follows.

1. Switch the tester to air discharge mode, and while holding down the discharge gun trigger switch, approach the test device from a distance at the fastest speed and make contact with it. 2. Keep away from the test device while holding down the discharge gun trigger switch.

Then release the trigger switch.

The test voltage is first implemented from test level 1, and then gradually increased to the target test level in the order of level 2 and level 3.

Please refer to "2 Laboratory Preparation" for the test voltage level.

For each application point, at least 10 single discharges should be applied for each polarity. (The application interval can be more than 1 second.)

Please keep the discharge return cable at a distance of at least 0.1m from the test device.

During the experiment, do not touch objects other than the discharge gun.

【 Reference 1 】

The rise time and peak current of air discharge current will vary with the discharge distance. (Usually, the longer the discharge distance, the slower the rise and the smaller the peak current.) In addition, the frequency components and discharge current contained in it will also change, so for high test level requirements, it is necessary to test from lower voltage to the required level.

【 Reference 2 】

The application position of air discharge will change according to the applied voltage.

2. When conducting indirect discharge

(1) When discharging the horizontal coupling plate

Use a conical discharge head.

Perform tests on all surfaces at a distance of 0.1m from the testing device.

The discharge gun is parallel to the surface of the horizontal coupling plate and contacts the cross-section of the horizontal coupling plate to discharge.

When changing the discharge surface of the test device, the test device should be moved (rotated) for discharge.

Please refer to "2 Laboratory Preparation" for the test voltage level.

For each application point, at least 10 single discharges should be applied for each polarity. Suggest applying with an interval of 1 second.

Please keep the discharge return cable at a distance of at least 0.1m from the test device.

During the experiment, do not touch objects other than the discharge gun.

(2) When discharging the vertical coupling plate

Use a conical discharge head.

Configure the vertical coupling plate at a distance of 0.1m from the end face of the test device. Connect two 470k Ω× discharge resistance cables to the reference grounding plane. ）Place the discharge gun vertically against the central part of the cross-section (vertical edge) of the vertical coupling plate for discharge.

If the side of the test device is much larger than the vertical coupling plate, the vertical coupling plate should be moved to cover the entire side.

The vertical coupling plate can exceed the horizontal coupling plate, but it is best to configure the vertical coupling plate on the insulation pad on the horizontal coupling plate.

For each application point, at least 10 single discharges should be applied for each polarity. (It is recommended to apply with an interval of 1 second.)

During the discharge test, do not touch objects other than the discharge gun.

3. Test methods for non grounded test devices

Position of indirect discharge to vertical coupling plate

When conducting static electricity tests on test devices that do not allow equipment to be connected to the grounding system due to device specifications or design (such as devices without grounding devices or battery drive, devices operated through AC adapters, etc.), in order to simulate single discharge phenomena, the charge on the test device must be eliminated before applying static electricity discharge.

In addition, metal parts such as the connector housing, battery terminal pins, and antenna must also be de energized before applying electrostatic discharge. There are the following methods to eliminate the charge carried on the test device.

(1) When using desktop devices

Connect the application site of the test device to the reference grounding plane through two 470k Ω× discharge resistance cables.

(2) When landing equipment

Connect the application site of the test device to the reference grounding plane through two 470k Ω× discharge resistance cables. The connection of the discharge resistor cable must ensure that the distance from the test device to the resistor is within 0.1m.

In addition, there are alternative methods for removing electricity, such as the following.

Set sufficient intervals for natural discharge application.

Use electric brushes.

If the test results of the installed discharge resistor cable are different from those of the uninstalled state, the results of the uninstalled state shall prevail.

In the experimental method, based on the direct discharge and indirect discharge mentioned above, at least 10 single discharges of each polarity should be applied to each application point, but the application interval can be more than 1 second.

4. Test methods for wall mounted devices

(1) If the installation surface is non-conductive

Place a non-conductive support with a height of 0.8m on the grounding plane and place the device on top for testing.

(2) If the installation surface is conductive

Maintain a distance of 0.8m from the grounding plane to the bottom of the device, and install it on a grounded metal wall for testing. There is no significant difference between other regulations and the testing of landing devices.

5. Testing methods for wearable devices

Conduct the test using a non grounded desktop device test configuration. In addition, as an additional experiment, in order to reproduce the most stringent discharge current conditions of wearable devices worn on the waist, the charging capacitor and discharging resistor were tested at 200pF and 50 Ω, respectively, for reference.