How to choose a surface resistance tester?
The surface resistance tester is an instrument for measuring the resistance of an object. It is an important tool for manufacturing and static control because it can be used to evaluate materials and classify them as conductive, dissipative and insulating materials. Surface resistance testers are also commonly used to test the effectiveness of static control products, such as reviewing anti-static work surfaces. Use the following guidelines to help you make a decision:
1. Accuracy: Not all resistance meters are the same for verification and qualification. Meters can be designed for quick measurements to confirm specifications (verification), while some meters are designed for more rigorous tests that require more precise measurements (identification). The accuracy required by the meter depends on the type of test you are going to perform. Choosing a higher-precision instrument will be a more expensive investment, and it can ensure quality measurements no matter what testing is required.
2. Test range
The minimum test range of static electricity is 10^3~10^12, covering the items of conduction, dissipation and insulation. Entry-level watt-hour meters only have this range, low resistance displays "less than 10^3" and high resistance displays "greater than 10^12". A higher precision resistance meter will have a larger test range. The test range of Metriso 3000 is 1 ohm ~ 1.2 ohm (1.2 x 10 12 ohm).
3. Voltage: Choose the right voltage for your application
Surface resistance testers use voltage to test the resistance of materials. The required voltage depends on the material to be tested and the test method. Usually used for ESD testing, conductive materials (1.0 x 10 4 ohms to <1.0 x 10 6 ohms) are tested under 10v, and the dissipation range of the materials (≥1.0 x 10 6 ohms to <1.0 x 10 9 ohms or <1 x 10 packaging material is 11 ohms) tested under 100v. (Learn when to use 10v and 100v). Most electric meters can be tested at 10v and 100v. They may automatically switch between the two based on the material, or you may have to manually select the voltage. The verification of insulating materials may require a higher voltage, such as 500v. There are meters specifically designed for this voltage, such as the Metriso 3000.
Another concept of resistance meter voltage to understand is "constant voltage". During the test, a meter with a constant voltage will not drop significantly from the selected voltage. For example, when 100 volts is selected, the meter will provide 96 100 volts in the probe (standard requirements ±5%). When the resistance of the tested material is low, some meters (called "open circuit") will reduce the voltage to a lower level to protect the meter from the return current. The constant voltage meter is a more accurate tool. Metriso 3000 is a constant voltmeter, which will display the output voltage of the probe during the test.
4. Result display: How will your meter display the measurement result?
The result is measured in ohms and sometimes displayed in powers of 10 (also called a decimal scale). The simplest readings are displayed with LED lights coded on a decimal scale, and colors are used to indicate conductivity, dissipation and insulation. The accuracy of the reading is poor, because the actual measurement value may fall between ten years and is rounded to the nearest number. More accurate meters will display the value digitally in decimal or ohms.
5. Temperature and humidity
Humidity and temperature will affect the electrical properties of the tested material. The material may meet the requirements at high humidity, but will fail at lower humidity. Therefore, we know the impact of the environment on test measurements and require it to be recorded.
Some resistance meters may have the ability to test built-in temperature and humidity, while others do not, and may require external equipment. If in doubt, it is best to buy a meter that can measure temperature and humidity. If your meter does not have this function, we will provide tools that can accurately measure temperature and humidity.
6. Measuring electrode
All surface resistance testers contact the material to be tested through components called electrodes. Electrodes can be built into the meter (called parallel electrodes) or they can be external components. The electrode required by the meter depends on the test to be performed.
Parallel electrodes: Two conductive rails are built into the back of the meter for quick resistance measurement. Not all meters have parallel electrodes.
External electrodes: Various external electrodes can be connected to the surface resistance tester according to the test type.
7, memory
Some meters record the measurement results in internal memory, which makes reporting very convenient. Recording measurements is a nice feature, but not everyone needs it. Our Metriso 3000 can store 50,000 data points and includes software for creating reports. Some intermediate resistance meters can also store data, such as Metriso SRM200. The number of data points required during the test will help you determine whether you need internal memory.