What Is Static Electricity?

Static electricity is a charge that is at rest. In the dry and windy autumn, people often encounter this phenomenon in daily life: when I undress and sleep at night, I often hear crackles in the dark, accompanied by blue light; when I meet and shake hands, my fingers just touched The other person will suddenly feel a pin-like tingling of fingertips, which is astonishing; when you get up and comb your hair in the morning, your hair will often float and become more and more chaotic; when you pull the door handle and open the faucet, you will be electrically shocked and often emit The "snap" sound, this is the static electricity that occurs in the human body.

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The so-called static electricity is a kind of static charge or non-flowing charge (the flowing charge forms a current). When charges accumulate on an object or surface, static electricity is formed, and charges are divided into positive and negative charges, which means that electrostatic phenomena are also divided into two types: positive and negative static electricity. When a positive charge accumulates on an object, a positive static electricity is formed. When a negative charge accumulates on an object, a negative static electricity is formed. However, whether it is positive or negative static electricity, when an electrostatically charged object contacts a zero-potential object (grounded Objects) or objects that have a potential difference from each other.

Human understanding of electricity begins with static electricity. The discovery and understanding of the phenomenon of static electricity, as in the West, is very early in China. There is a record of "() sucking mustard" in "Chun Qiu Wei Kao Yi You" in the late Western Han Dynasty. Wang Chong's "On the Balance and Chaos Dragons" has further records: "Dun Mou (that is, ) mustard mustard and magnet lead needles are all true and not fake. Others are like Xiao and cannot be captured. What's the matter? Different temperaments, can't move each other. " ^[1]

There are many hazards of static electricity, and its first hazard comes from the interaction of charged bodies. When the aircraft body is rubbed with particles such as air, water vapor, dust, etc., the aircraft will be charged. If no measures are taken, it will seriously interfere with the normal operation of the aircraft radio equipment. In the printing factory, the static electricity between the paper pages will cause the paper pages Adhesive, difficult to separate, bring trouble to printing; in pharmaceutical factory, because static electricity attracts dust, the medicine can not reach the standard purity; static electricity on the surface of the screen when the TV is put on is easy to attract dust and oil, forming a A layer of dusty film reduces the sharpness and brightness of the image; the dust that is common on blended clothes and not easy to take off is also a ghost of static electricity. The second major hazard of static electricity is the possibility of igniting some

Anti-static in daily life

1. Wash your hands before going out, or put your hands on the wall to remove static electricity, and try not to wear chemical fiber clothes.

2. To avoid static electricity, you can use small metal devices (such as keys), cotton wipes, etc. to touch the door, doorknob, faucet, chair back, bed rail, etc. to eliminate static electricity, and then touch it with your hand.

3 Wear cotton underwear.

4 When you are ready to get out of the car, hold the gear with your right hand, then touch the iron part below with your fingers, then drive the door, put your left hand on the door with iron, but do nt loose your left hand, then let go of your right hand, get out of the car, At this time, if you hold the door with your right hand, you will not be charged.

5. To deal with static electricity, we can adopt "anti" and "put" both hands. "Anti", we should try to choose pure cotton products as the fabric of clothing and home accessories, and try to avoid using chemical fiber carpets and furniture with plastic as the surface material to prevent friction and electricity. Keep electrical appliances such as TVs and refrigerators as far away as possible to prevent induced electrification. "Discharge" is to increase the humidity so that local static electricity is easily released. When you turn off the TV and leave the computer, you should immediately wash your hands and face so that the electrostatic charges on the skin surface are released in the water. In winter, try to choose high moisturizing cosmetics. Humidifier commonly used. Some people like to keep ornamental fish and daffodils indoors is also a good way to regulate indoor humidity.

In addition, an economical and practical method of humidification is recommended: put a basin of water under the heater, use an old towel (or a good absorbent cloth), put one end in the water, and put the other on the heater, so that it can evaporate into the room around the clock. Three liters of water. If every heater does this, the entire room will feel moist and pleasant. You might as well try it.

6. Taking frequent baths and changing clothes can effectively eliminate static electricity accumulated on the surface of the human body.

Here are two tips to help prevent this type of shock.

1. In the house, static electricity may be generated after the carpet rubs against the sole of the shoe, and it may also be charged by wind due to wind. At this time, be careful when touching the iron door when entering or leaving, your hands may be hit by electric shock. After repeatedly encountering such a situation, you can take the following measures to avoid electric shock:

When touching the iron door, do not directly touch the iron door directly with your hand, but grasp a bunch of keys with a large area by hand first, and then use the tip of a key to touch the iron door, so that the electricity on your body will be discharged, and No electric shock.

Principle: The pain in the discharge of the hand is due to the high-voltage discharge. Because of the extremely small area of contact when the hand suddenly comes into contact with the iron gate during the discharge, instant high voltage is generated. If you take out the key in your pocket, first hold the key in a large area (a bunch of keys can not transfer much charge and there will be no electric shock at this time), and then use the tip of a key to contact a large conductor. At this time, The contact point of the discharge is not a point on the skin of the hand, but the tip of the key, so the hand does not feel pain.

2. Electric shocks often occur when getting off taxis. It is mainly due to the static electricity accumulation caused by the friction between the body and the seat when getting out of the car, and when the door is closed after getting out of the car, the hand suddenly hits the iron door and will be shocked.

When this situation often happens, it is best to pay attention: when getting off the car, that is, when the body is rubbing against the seat, hold the metal door frame in advance, you can discharge the static electricity on the body at any time when the friction generates static electricity, so as not to After getting out of the car, I suddenly discharged when I touched the iron door.

Antistatic for pregnant women

Pregnant women can prevent static "harassment" of static electricity by choosing a variety of suitable flowers and plants indoors, or choosing the right humidifier to keep the living environment with proper humidity. Hair or chemical fiber clothes are prone to static electricity. Pregnant women are advised to prepare more cotton clothes.

Avoid prolonged contact with the computer, open the window when watching TV or computer, wash hands and face after watching, and use skin care products with good moisturizing properties to ensure skin moisture, while pregnant women living in electrostatic fields for a long time, because of its The accumulation of static electricity in the body causes the blood PH value to be alkaline, so it is necessary to appropriately increase the intake of vitamin C, A, E and acidic foods, such as carrots, cabbage, and tomatoes can increase the acidity of the blood and maintain the normal electrolyte balance of the body.

Anti-static in industrial production

In industrial production, especially in electronics production processing and flammable and explosive production sites, electrostatic protection should be taken very seriously.

The implementation of international and domestic industry standards such as ESD20.20, IEC 61340, SJT 10694, MT 520 can effectively prevent electrostatic hazards.

From a standard point of view, the main tasks of antistatics in industrial production are: 1. Formulate control plans according to production; 2. Staff training; 3. Infrastructure and protective products; 4. Plan implementation supervision, inspection of facilities and protection.

Examples of common protection methods:

1.Control of environmental hazards

2. Process control

3 Ground

4 Increase humidity

5. Antistatic additives

6. Static neutralizer

7. Use anti-static equipment

8. Strengthen electrostatic safety management.

The most effective measure is to "connect" or "ground" the human body to the earth. Therefore, people should wear anti-static shoes. To keep the human body connected to the ground, this requires that the ground is also anti-static before the human body's static electricity can be introduced into the ground. Therefore, the ground can be grounded with anti-static mats, anti-static composite rubber sheets, and grounded with anti-static grounding wires, such as funds. Adequate, you can use anti-static raised floor, especially in the planning and design of the equipment room, you can consider the use of anti-static raised floor, if the equipment room has been established and the equipment has been installed, and do not want to install anti-static equipment to stop production of these equipment, etc. When it is affected, anti-static floor mats and anti-static composite rubber sheets, which are simple in construction and inexpensive, can also be selected.

When people wear anti-static shoes and have anti-static floor mats, anti-static composite rubber boards, or anti-static raised floors, they must have a good anti-static effect? When people wear anti-static shoes and have anti-static floor mats, anti-static composite rubber boards, or anti-static raised floors, they may not have a good anti-static effect. Usually people also wear socks and insoles. Young people's feet are prone to sweat. These socks and insoles can also conduct static electricity, but in the middle of the elderly, the socks and insoles cannot be conducted because the shoes are dry during the dry season. Static electricity, and many manufacturers only require staff to wear anti-static clothing and anti-static shoes, ignoring the adverse effects of socks and insoles, so these anti-static shoes and anti-static floor can not play an anti-static role. Therefore, a "body integrated resistance tester" is placed at the entrance of the machine room or plant, which can quickly and accurately detect those wearing unqualified antistatic shoes, socks and insoles.

Wear an antistatic suit with an antistatic corded wrist strap to discharge static electricity from the human body through the wrist strap ground wire.

Control of static electricity in production workshop

Electronic processing companies often have headaches due to the inability to grasp the occurrence of static power. It is recommended that workers do not be afraid of static electricity. As long as workers take various protective measures, they can completely control static electricity. Static discharge or static dissipative work surface is an electrostatic safety An indispensable part of the workstation, especially those manually assembled production workshops, when using an anti-static wrist strap, it is necessary to clean the work surface and properly connect it to a common point to ground. Continuity.

1.Grounding

Grounding is very important to reduce the static charge generated on the conductor. The human body is the conductor and the ground where the static electricity is generated. Therefore, we must reduce the electrostatic charge on people who come into contact with sensitive antistatic components or components. The static electricity generated by the human body is best grounded through the human body, and to ensure that the grounding is good and effective.

Several personal grounding devices

In the industry, wrist straps are the most commonly used grounding device. The wrist strap will safely and effectively remove the static charge on the human body. To properly play the role of a wrist strap, it is necessary to reasonably contact the skin. A dirty or loose wrist strap may retain the electrostatic charge that has been lost, making the antistatic control ineffective. Workers with dry skin must wipe the antistatic hand cream to achieve a better static discharge path between the body and the wrist strap. Conductive footwear or foot grounding can be used or supplemented by insufficient wrist straps. Workstation grounding device

2.Isolation

The next concept is to isolate gas components and components during storage or transportation. Isolate from a charged object or a charged electrostatic field. Insulators are the best way to prevent electrostatic discharge damage from occurring during storage or transportation. Since grounding cannot remove static charges or insulators, it is necessary to isolate sensitive components and components from them. Reducing conventional plastic and other types of insulators in stationary work, shipping, and handling areas is the best way to isolate products from insulators. Isolation can also be accomplished by restricting access to the entire work area or workstation. Finally, we take advantage of the fact that static charges cannot enter containers made of conductive materials or layers. This effect is called the Faraday Cup effect. When storing and transporting electronic components or loading circuit boards, make sure that containers with similar Faraday cup characteristics are used. These containers will be isolated from electrostatic discharge injuries.

Faraday Cup

This type of Faraday cup is commonly used to control electrostatic discharge. It is a metal bag, a conductive bag, and a covered turnover box. These Faraday cups can carry these electrostatic charges on the surface and remove it before opening.

3. Neutralize

Since grounding and isolation will not release charge from insulators such as synthetic cloth or conventional plastic, neutralization is important. Neutralization or removal of the electrical charges that are naturally generated in the process from the insulator is called ionization. Ions are simply charged substances that exist in the air. Ions are produced by natural energy substances. They include sunlight, lighting, open flames and radiation. We can create trillions of ions through ionizers. Ionizers use high voltages to generate a balanced mixture of charged ions, and use fans to help ions drift onto objects or areas to neutralize them. Ionization can neutralize the static charge on the insulators within five seconds, thus reducing their potential damage. Since ionization is not a substitute for grounding or isolation, ionization only reduces the possibility or risk of an electrostatic discharge accident.

4. Prevention

Prevention is another important measure or device for you. This is the most critical factor in electrostatic discharge control. Others or you must be aware of the dangers of electrostatic discharge in your work with electronic components. Understanding them and adapting to them will be the most important thing to note than any electrostatic discharge control material.

Electrostatics mainly studies electrostatic application technology, such as electrostatic dedusting, electrostatic copying, and electrostatic biological effects. The most important thing is electrostatic protection technology, such as the electrostatic hazards in the electronics industry, petroleum industry, weapon industry, textile industry, rubber industry, and the aviation and military fields. Seek to reduce the losses caused by static electricity. The widespread application of electronic technology and the electromagnetic environment are becoming more and more complex. The electromagnetic field effects of electrostatic discharge such as electromagnetic interference (EMI) and

Electrostatic engineering refers to the specialized science that has been researched on electrostatic hazards and their protection and electrostatic application technology based on electrostatics from the early nineteenth century to the present. Its main research contents include electrostatic application technologies such as electrostatic dedusting, electrostatic copying, electrostatic biological effects, etc., and electrostatic protection technologies such as electronics industry, petroleum industry, weapon industry, textile industry, rubber industry, and aerospace and military fields.

In the construction quality, some construction teams do not know the anti-static knowledge at all, and the ground wires are randomly connected and some are not grounded. If the above problems are not rectified in time, anti-static flow will be in the form, which will cause very large losses in the application of modern microelectronics and play a hindrance. Therefore, the anti-static industry association and relevant government departments need to take a series of measures to enable the anti-static industry to develop healthily. The first is through media promotion, so that managers of the industry and users, fully understand the importance of static electricity and the causes of static electricity, so that users from passive to active use of anti-static technology. Secondly, those who are in contact with microelectronics technology and the majority of those engaged in antistatic business really understand the significance of antistatic. Thirdly, through the ISO9000 quality control system to strengthen the implementation of product quality supervision and implementation of the quality certification system, without a qualified product certification is not allowed to sell in the market, some non-standard enterprise production products must be taken. Fourth, we must strengthen the measurement of the anti-static environment and make it standardized and institutionalized. Dry climate, widely used in chemical fiber and plastic.

Electrostatic induction is a phenomenon in which a conductor has positive and negative charges on different parts of the surface due to the influence of an external electric field. Generally under the action of the electric field of a charged body in its vicinity, the free electrons in the conductor are redistributed until the intensity of the electric field in the conductor is reduced to zero. As a result, a charge with a different sign from the charged body appears at one end and a charge with the same sign appears at the other end. When electrostatic induction occurs, the induced charges obtained by electrostatic induction must be generated simultaneously, and the positive and negative charges are equal. When the charged body is removed, the charge on the conductor will return to its original uncharged state.

Electrostatic interference

The electrostatic interference generated by the human body can change the normal potential difference on the human body surface, affect the normal electrophysiological process of the heart muscle and the normal conduction of the electrocardiogram without interference. This kind of static electricity can aggravate the patient's condition or induce premature beats. Long-lasting static electricity can also increase the alkalinity of the blood, leading to a decrease in the calcium content in the serum and an increase in the excretion of calcium. The body's physiological balance, disturbing people's emotions, etc. ^[3]

Equipment leakage, especially small leakage that will not cause electric shock to people is not static electricity. Although in most cases people can barely feel it, due to its universality (some electrical equipment has some leakage) and high internal resistance, it produces a peak that approximates the power supply voltage (100 ~ 400V) for a short time.

So far, humans can distinguish between three types of electrical energy; AC, DC, and static electricity.

Static electricity can not be effectively controlled under the current technical conditions. Without suitable materials to isolate and transmit it, it is difficult to distinguish the position of its positive and negative electrodes, and the magnitude of voltage and current cannot be changed. Most of the methods adopted are to install shielding Cover or ground wire to release it for the purpose of protecting other equipment.

Static electricity can move and store energy in insulating materials, and this natural phenomenon is not reasonably explained in the theory of physics.

? The special characteristics of ESD / EOS: First, certain conditions and processes are required for the generation and accumulation of static electricity. Therefore, it is not necessary to protect the product from ESD / EOS without protection. There are certain accidents; ESD / EOS energy is small, so those who are harmed by ESD / EOS do not appear to be scrapped immediately. Some only show increased leakage, unstable work, and even not obvious in the factory test for a while. It is easy to blame the problem later. Poor materials or poor design and introspection often make people unaware of the dangers of ESD / EOS, and they are fortunate.

The static test standards are divided into device level and system level. Device-level ESD is divided into HBM, MM, and CDM. Among them, related specifications of HBM include MIL-STD-833H Method 3015.8 (US military standard), JS-001-2012 (Joint specification issued by ESDA-JEDEC), AEC-Q100 (Automotive Electronics Association). CDM related specifications include STM5.3.1-2009 (American Electrostatic Association), JEDEC EIA / JESD22-C101-E (Electronic Engineering Association), but the above two standards have been JS-002-2014 (the joint standard issued by ESDA and JEDEC) Was replaced. The CDM test specification for the automotive industry is AEC-Q100-011-B. MM is currently deprecated.

IEC 61000-4-2 Electromagnetic compatibility (EMC)-Part 4: Testing and measurement

techniques-Section 2: Electrostatic discharge immunity test. Basic

EMC Publication (Electromagnetic Compatibility (EMC)-Part 4: Testing and Measurement Techniques-Section 2: Electrostatic Discharge Immunity Test.

Basic EMC publications), China's national standard GB / T 17626.2 "Electromagnetic compatibility test and test technology, Electrostatic discharge immunity test"

The highest test voltage required by IEC 61000-4-2 and GB / T 17626.2 is a contact discharge of 8kV and an air discharge of 15kV (excluding special voltages of open class).