Today, with the development of science and technology, the application fields of electronic measuring instruments, analytical instruments and other instrumentation products are more and more extensive, but these high-end instruments are still not understood by many people!
Guangzhou Instrument and Meter Company found that many people don't know much about the block resistance. They don't even know what it is. The insider knows it, so let's introduce the block resistance!
Evaporating aluminum film, conductive paint film, printed circuit board copper foil film and other film-like conductive materials, the best way to measure their thickness is to test their square resistance. What is square resistance? The square resistance is the square resistance, also called the square resistance, which refers to the resistance of a square thin film conductive material from side to side, as shown in Figure 1, that is, the resistance value from the B side to the C side. The sheet resistance has a characteristic that the square-to-edge resistance of any size is the same. Regardless of the side length of 1 meter or 0.1 meter, their square resistance is the same, so that the square resistance is only related to the thickness of the conductive film and the like. related.
How to test the sheet resistance, can you directly test the material shown in Figure 1 with the multimeter resistance file? No, because the multimeter's test pen can only test the resistance between points, and the point-to-point resistance does not mean anything. To test the square resistance, we first need to press a round copper rod with a much smaller resistance than the conductive film on the A side and the B side, and the round copper rod has a high finish to make good contact with the conductive film.
In this way, we can measure the square resistance of the conductive film material by testing the resistance between the two copper rods with a multimeter. If the square resistance is relatively small, such as a few ohms or less, because of the contact resistance and the performance of the multimeter itself, there are cases where the reading is unstable and the measurement is not accurate. At this time, it is necessary to use a special low-resistance test instrument with four-terminal test, such as a milliohm meter, a micro-ohm meter, and the like. The test method is as follows: press four conductive copper rods on the conductive film, as shown in Figure 2. The four copper rods are represented by A, B, C, and D. They are soldered with wires to the milliohmmeter. We make the distance L between BC equal to the width W of the conductive film. As for the distance between AB and CD, there is no distance. The requirement is generally 10-20 mm. After the milliohm meter is turned on, the resistance value displayed by the milliohm meter is the square resistance of the material.
Well, through the above introduction of Guangzhou Instrument and Meter Company, I have some understanding of this square resistance! For more information, please continue to pay attention
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