Perform ESD measurement to check the limit values
In order to prevent damage to electronic components due to electrostatic discharge, the materials used – for example in production – must be checked for ESD protection by means of regular ESD measurements.
Why ESD measurements are important
ESD materials also wear out and age over time, which can cause them to lose their ESD protection in the worst case scenario. For this reason, an annual ESD measurement has become established as the ESD measurement interval for all control elements, which checks whether the required ESD protection of the respective materials is still provided.
As even discharges and equalizing currents that are imperceptible to humans can damage electronic components, it is necessary to use ESD measuring devices for ESD measurements. This is because a semiconductor module can be destroyed by an electrostatic discharge of just 30 volts, while 5 volts is sufficient for sensitive components such as microchips. Humans, on the other hand, only feel a discharge from 3000 volts. Discharges can be heard from 5000 volts and a discharge spark or discharge flash is visible from 10000 volts.
The level of voltages involved in an electrostatic discharge depends on both the activity and the humidity, as can be seen from the following table:
| Type of activity | Humidity 10 % | Humidity above 60 % |
| Moving around the workplace | 6000 Volt | 100 Volt |
| Packaging paper in plastic wrapping | 7000 Volt | 600 Volt |
| Walking over plastic flooring | 12000 Volt | 250 Volt |
| Removing bubble wrap from conductor tracks | 26000 Volt | 1000 Volt |
| Walking over carpeting | 35000 Volt | 1500 Volt |
The sensitivity to electrostatic voltages depends on the component in question. In the case of semiconductors, for example, there are different types, each with different ESD sensitivities, as shown in the following table:
| Semiconductor type | ESD sensitivity |
| CMOS | 250 – 2000 Volt |
| EPROM | 100 – 500 Volt |
| Film resistor | 300 – 3000 Volt |
| Junction-Fet | 140 – 1600 Volt |
| MOSFET | 100 – 200 Volt |
| Operational amplifier (bipolar) | 190 – 2500 Volt |
| Operational amplifier (Fet) | 150 – 500 Volt |
| Schottky diodes | 300 – 2500 Volt |
| Schottky TTL | 300 – 2500 Volt |
| Thyristor | 680 – 2500 Volt |
| Transistor, bipolar | 380 – 7000 Volt |
| V-MOS | 30 – 1800 Volt |
The materials used for ESD protection are differentiated according to their conductivity. In the case of so-called conductive materials with a surface resistance between
| Surface resistance | 102 Ω /103 Ω /104 Ω | 105 Ω /106 Ω /107 Ω /108 Ω /109 Ω / 1010 Ω / 1011 Ω | 1012 Ω / 1013 Ω |
| Material type | conductive (conductive) materials | Dissipative materials | insulating materials |
ESD measurement methods
There are different measurement methods for testing the ESD protection of a material.
Measurement of the surface resistance
The surface resistance is measured either using the so-called point-to-point measurement or with a single electrode, whereby the results should theoretically differ greatly depending on the measurement method selected.
When measuring point-to-point resistance, the resistance between two points on a surface is measured using a megohmmeter and two electrodes.
The measurement of the surface resistance with only one electrode is carried out either with the aid of a round electrode, which has two parallel connections, or with the aid of a concentric ring electrode.
Measurement of the contact resistance
The contact resistance is measured by placing one electrode on one side of the material to be tested and the other electrode on the other side.
Measurement of the leakage resistance
When measuring the leakage resistance, the resistance between an electrode on a surface and a protective conductor is measured.
The leakage resistance can also be measured for people, whereby the measurement is carried out via the combination person-shoes-floor.
ESD measuring devices
There are special ESD measuring devices for ESD measurements, which are usually used to measure the leakage resistance and surface resistance. In addition to resistance, ESD workplaces also need to measure whether an electrostatic field is present. Electric field meters or so-called charge plates are used for this purpose.
And if there is an ESD floor, the voltage generated when walking over it must be measured using the so-called walking test, for which there is a special measuring system.
You can also buy ESD measuring devices from the abovo online store, such as the following:
- Resistance meter RM 1000
- Resistance meter RM 4000
- Electric field meter/ charge plate
- Walking Test-Measurement system
Do you have any questions about ESD measurement or ESD measuring devices?
If you would like more information on ESD measurement or ESD measuring devices, our experts at abovo can help you. We are also happy to visit our customers to carry out ESD measurements and / or present our ESD measuring devices.
Simply give us a call or send us an e-mail with your request:
- You can reach the abovo experts by telephone on: +41 32 552 44 44
- You can reach the abovo experts by e-mail at: info@abovo.ch
