In an ESD test of a project, when the electrostatic gun is close to the outer casing of the plastic machine floating product, the air is discharged at 12KV, and the machine is prone to crash, restart or VDD damage. In this paper, we avoid the lightness, and the point of EMC reflects the surface and body of EMC. We choose the EMC point of materials and devices, and elaborate on the characteristics and applications of dielectrics.
The content of electromagnetic compatibility research is extensive. It starts from the three elements of EMC, organizes research and publishes standards and methods by international standards, and evaluates the third-party laboratory simulation test to the actual application site and final referee, covering physics and chemistry. , natural sciences and engineering sciences such as environment, materials, electronics, industrial engineering, and measurement.
For the EMC design of enterprise products, when EMC problems are encountered in project engineering design, we always use different methods to solve them. The cost and the solution are often different. The main reason is the characteristics of each EMC problem. They are all very different, so the corresponding solutions and strategies are not the same.
In this paper, we avoid the lightness, and the point of EMC reflects the surface and body of EMC. We choose the EMC point of materials and devices, and elaborate on the characteristics and applications of dielectrics.
ã€Symptom】In an ESD test of a project, when the electrostatic gun is close to the outer casing of the plastic machine floating product, the air is discharged at 12KV, and the machine is prone to crash, restart or VDD damage.
Quick positioning: Through disassemble analysis, we found that the ESD path starts from the external electrostatic gun, passes through the gap between the upper and lower sides of the plastic case, and then hits the PCBA to hang the software system and hardware system on the PCBA, causing various ESD failures. .
In-depth analysis: use the transparent glue to wrap the bare test points on the PCBA as shown, and verify 15KV OK on several machines; the joint structural engineer calculates the creepage distance of the case to PCBA is 5mm, creepage distance Obviously not enough, by pulling the creepage distance between the electrostatic gun and PCBA to 10mm, 15KV is OK even without any measures. Taking into account the project structure, production, reliability and other factors, we took another way, put the next line of white or green oil, the test is still OK.
ã€Rectification program】Considering that the creepage distance cannot be changed, for the products already produced, you can use the sticky adhesive tape to stick to the PCBA or directly spray the green oil to cover the test point. For the subsequent revision, it is recommended to move the test point directly. The center of the PCBA, and the GND copper is exposed on the side of the PCBA board.
In this case, the principle of the two poles of the capacitor is utilized. If the intermediate medium is not broken down, it is the principle of "field". If it is broken down, it is the principle of "road".
The capacitor is broken down, the medium is no longer insulated, becomes a conductor, becomes the wire of the circuit; the medium is not broken down, the medium is still insulated, the capacitor is still a capacitor, and the middle is an electric field.
It is suitable for the computers.inspection appliance and instruments with rated voltage up to 300/500V. This product presents an excellent performance in high
frequency locations
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