Iec61000-6-1/-2 Esd Test Equipment
Three important rules of electrostatic discharge generator EMC
1. Law of EMC cost-effectiveness relationship: the earlier EMC problems are considered and solved, the lower the cost and the better the effect.
EMC design can be carried out in the development stage of new products, which can save the cost and improve the efficiency greatly compared with the improvement after the product EMC test fails.On the contrary, the efficiency will be greatly reduced and the cost will be greatly increased.
2. The larger the area of high-frequency current loop S is, the more serious EMI radiation is.
High frequency signal current flows through the inductance minimum path.When the frequency is higher, the general line reactance is greater than the resistance, the connection to the high-frequency signal is the inductance, series inductance caused by radiation. Most of the electromagnetic radiation is generated by high-frequency current loops on EUT's devices, the worst of which is the form of an open antenna. The corresponding treatment method is to reduce or shorten the connection line, reduce the area of high-frequency current circuit, and eliminate any antenna needed for abnormal work, such as discontinuous wiring or excessively long pins of components with antenna effect.
3. The higher the loop current frequency f is, the more serious the EMI radiation is caused, and the electromagnetic radiation field intensity increases in proportion to the square of the current frequency f.One of the most important ways to reduce the radiation disturbance or improve the anti-interference ability of radio frequency radiation is to try every means to reduce the high-frequency current frequency f of the disturbance source, that is, to reduce the frequency f of the disturbance electromagnetic wave.
Iec61000-6-1/-2 Esd Test Equipment
Selection of emi filters for electrostatic discharge generators
Practice shows that even for a well designed product with correct shielding and grounding measures, there will still be transmitting or transmitting interference into the product. Filtering is an effective method to compress the spectrum of interference. When the spectrum of interference is different from the band of useful signal, the useless interference can be filtered out by electromagnetic interference filter.
- Signal line filter
Signal line filter is a low pass filter used on various signal lines to filter out high-frequency interference components. It can be divided into circuit board filter, feed-through filter and connector filter. Circuit board filter is suitable for installation on circuit board, which has the advantages of low cost and convenient installation.The feed-through filter is suitable for mounting on the shield housing, especially when a single wire or cable passes through the shield;Filter connectors are suitable for use when multiple wires or cables pass through the shield.
- Ferrite emi suppression element
Ferrite is a kind of ferromagnetic material with cubic lattice structure. Its manufacturing process and mechanical properties are similar to those of ceramics, and its color is grayish black.For ferrites used to suppress electromagnetic interference, the most important performance parameters are permeability muon and saturation flux density Bs. Muon can be expressed as a complex number, real part of the inductance, imaginary part of the loss, with increasing frequency.Therefore, its equivalent circuit is a series circuit composed of inductor L and resistance R, both of which are functions of frequency. For example, the permeability of 850 ferrite, impedance is less than 10 Ω when 10 MHZ, while more than l00MHz impedance is greater than 100 Ω, after the high frequency disturbance attenuation greatly.In this way, a low pass filter is formed.At low frequency, R is small, L plays a major role, and electromagnetic interference is reflected and suppressed.At high frequencies, R increases and electromagnetic interference is absorbed and converted into heat energy.
- Power line filter
The power cord is the main way for electromagnetic interference to and from equipment.To prevent both of these situations, a power line filter must be installed at the power interface of the device. It only allows the power supply frequency to pass through, but electromagnetic interference above the power supply frequency is greatly attenuated.The interference on the power line comes in two forms. The interference on the hot line and zero line is differential mode interference, and the interference on the hot line, zero line and ground line is common mode interference. Although the power line filter can suppress the differential mode interference and the common mode interference, but the effect is different, the insertion loss of the two should be given respectively.All power filters must be grounded, except those that are specifically allowed to be ungrounded, because the common-mode bypass capacitor in the filter only works when grounded. When using a power filter, install it as close as possible to the power inlet and isolate the input/output end of the filter to avoid direct coupling of electromagnetic interference from the input end to the output end of the filter.In addition, the grounding point of the filter should be as close as possible to the grounding point of the equipment.The technical specifications of power line filter include: maximum leakage current, withstand voltage, rated operating frequency, rated operating voltage, rated operating current and temperature range.
Electromagnetic compatibility components are the key to solve electromagnetic interference emission and electromagnetic sensitivity problems.Electrostatic discharge generator manufacturers remind you to have a thorough understanding of these components, so that it is possible to design standard requirements, the performance ratio of the best electronic and electrical products.
Iec61000-6-1/-2 Esd Test Equipment
Problems and causes during ESD test
Due to the complexity of ESD problems, it is difficult for experienced engineers to ensure the safety of ESD problems. It is very important for products with ESD problems to find effective solutions accurately and timely. The ESD test of product prototype is a common problem encountered by engineers of electrostatic discharge generator manufacturers. Problems and causes can be found and analyzed according to the following steps.
- Let the ESD discharge Gun (ESD Gun) approach the discharge point from different directions, observe the different discharge phenomena, pay attention to the discharge intensity and direction of the anti-spark, and analyze how static electricity enters the fuselage.
- Gradually increase the discharge voltage of ESD discharge gun from low to high, and observe which voltage interval the failure occurs in GSM mobile communication terminal. For example, during the air gap discharge test, the failure occurs from 2kv, 4kv, 6kv to 8kv, and 10kv, 12kv and 15kv if necessary.
- GSM mobile communication terminal can be photographed on the front, back or side, mark the discharge point, mark the discharge spark direction if necessary, and record the experimental phenomenon of each discharge point in detail.For example, at a certain point in a positive voltage value or voltage value of the discharge number, the number of faults and each fault phenomenon, is not recoverable damage, automatic shutdown, reset or LCD display abnormal, are recorded in detail for analysis.
- It should be noted that: the experimental phenomenon of a prototype is always random. It is necessary to carry out the same test on several prototypes and make the fault reappear so as to accurately analyze the cause of the fault.Generally, a test needs at least 5 prototypes, preferably 10.
- According to the analysis of experimental phenomenon, judge the cause of failure.As the failure reasons of ESD are various, several different reasons may be analyzed from one phenomenon, one or several of which cause ESD failure of GSM mobile communication terminal.This requires engineers to carry out further analysis, specific experiments for each possibility, and finally find the real cause of the fault.