EMC engineers need to know about "shielding anti-static materials" and other related matters

The things about EMC shielding and anti-static materials

People often say that fire is "easy to hide" and static electricity is "difficult to prevent". Stripping off clothes and touching door handles It's possible to be attacked by a trace of "microcurrent". Do you think that's the "damage value" of static electricity? Don't underestimate its nickname 'invisible killer', as it causes numerous fires every year due to static electricity.

01. What is static electricity

The most common way to generate static electricity is through contact separation and electrification. When two objects come into contact and the distance between them is less than 25 × 10-8 cm, electron transfer will occur, and two layers of charges of equal size and opposite polarity will appear on both sides of the interface. When the two objects quickly separate, static electricity may be generated. Secondly, due to the different electrical resistivity of objects, objects with high electrical resistivity have poor conductivity and difficult electron transfer in the charged layer, which constitutes the condition for static charge accumulation. According to relevant information, when the resistivity of a liquid is between 1010 and 10159 • m, it can generate dangerous static electricity, while the maximum static electricity is generated at 10132 • m. When it is higher than 10159 • m or lower than 10109 • m, the generation and accumulation of static electricity are so small that they can be ignored. Especially when the electronegativity is below 1062 • m, it acts as a conductor for static electricity, and the issue of static electricity can be ignored.

Static electricity is easily adsorbed onto small objects, such as hair and fibers on clothing. It is only necessary to regularly clean the environment to prevent these small objects from coming into contact with electric charges and generating static electricity.

Static electricity can be generated under electromagnetic induction, such as in washing machines, televisions, etc. Therefore, when we come into contact with washing machines, televisions, etc., we can wear gloves to avoid direct contact between the human body and electric charges, naturally preventing static electricity from being generated.

Try to wear less synthetic clothing as it can easily generate static electricity, and also avoid using synthetic carpets and other items at home. If you find a gas leak at home, be careful not to take off your clothes at this time, as taking off your clothes may also generate static electricity, causing greater harm. It is best to remove the power plug of computers, tablets, etc. in the dormitory when not in use, and try not to watch TV in bed as it is healthier for the body.

02. Six methods

Six methods for preventing static electricity in households:

1. Wash hands and face frequently to release static electricity on the surface of the skin in water;

2. Do not wear synthetic clothing, all cotton clothing can effectively suppress static electricity;

3. Touch the wall. If you are particularly susceptible to electricity in a certain area, touch the wall first and then touch it again;

4. Dip the comb in water before combing your hair. If it is a wooden or cow horn comb, you can use it with confidence;

5. Maintain a certain humidity indoors, mop the floor frequently, and use a humidifier if necessary;

6. Drink more water and apply more moisturizer. Take at least two baths per week, and the water temperature should not be too high, otherwise it will damage the surface oil of the skin and exacerbate dryness. After taking a shower, it is best to apply a little moisturizer to lock in moisture and relieve dryness.

7. For items that are easily charged, a slightly damp cloth can be used to wipe them before contact to eliminate static electricity on their surface. After turning off the TV and leaving the computer, you should immediately wash your hands and face to release the static charges on the surface of your skin in the water. Carry a coin or metal key with you on a regular basis. Before using the computer, touch a coin or key with a water pipe or radiator to discharge static electricity from the body.

8. Wear fewer headphones in winter. The static electricity brought by headphones can damage the human ear. If there is a lot of static electricity in the human body, it will be released into the ear canal through the headphones.

9. Try not to touch your hair with your hands. Some people like to insert their fingers into their hair and use the gaps between their fingers to comb their hair. However, in winter, if the hands are not moisturized properly, static electricity can easily be generated when touching the hair.