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EMC test in LED
Release time:2014-05-26   Click times:3683

About LED ESD protection

      Electrostatic discharge may cause LED sudden failure or potential failure. Sudden failure LED cause permanent failure, short circuit. Potential failure will enable the LED degradation of performance parameters, such as leakage current increase, subject to the general risks of GaN-based LED formed after electrostatic damage can not be repaired.

1, the electrostatic surface is the presence of excess or shortage of electrostatic charge, which is a power.

Static electricity is the result of positive and negative charges in the local area to lose balance, electrostatic transfer by electrons or ions formed.

2, static object is stationary relative to the charge brought.

Electrostatic characteristics:

High potential: up to tens of thousands to hundreds of thousands of volts, the operation often several hundreds of kilovolts. Low power consumption: static flow mostly microamps (uA). Short duration of action: nanosecond. By the large environmental impact: especially humidity, humidity rises, electrostatic drop.

Generation of static electricity:

Contact, friction, impulse flow, piezoelectric, temperature, freezing, electrolytic

Electrostatic hazards:

Electrostatic discharge (ESD) caused by light-emitting diode PN junction breakdown is the main way of LED device packaging and assembly applications in industrial electrostatic hazards. Electrostatic damage has the following characteristics:

1, hidden: the human body can not directly perceive static, even if electrostatic discharge occurs, the body does not necessarily have the feeling of shock, this is because the human perception of static discharge voltage of 2-3KV. Most cases are tested or practical application, in order to find LED devices have been damaged by static electricity.

2, latent: LED Electrostatic discharge may cause sudden failure or potential failure. Sudden failure LED cause permanent failure: short-circuit. Potential failure will enable the LED's

Deterioration of performance parameters, such as leakage current increase, subject to the general risks of GaN-based LED formed after electrostatic damage does not in any way be cured.

3. Complexity: in the case of electrostatic discharge, the discharge power from the space charge, and thus it is limited stored energy, the power supply does not have the additional ability to sustain discharge, so that it can only provide a partial strike occur briefly wear energy. Although electrostatic discharge energy is small, but the discharge waveform is complex and control them too much trouble. In addition, LED extremely fine, failure analysis difficult, it is easily mistaken electrostatic damage failure as other failure, prior to electrostatic discharge damage is not fully understood, is often attributed to early failure or the failure is unknown, which unconsciously cover up the real reason for the failure.

4, Severity: ESD potential failures caused only some parameters of deterioration, if not more than the acceptable range, it means that the LED may be damaged by unaware final test, leading to early failure occurred, which manufacture for all levels business, the result is the most damaged reputation. ESD occurs very rapidly at very high intensity discharge current flowing through the LED PN junction, the Joule heat generated so that the local molten medium between chip PN poles, causing a short circuit or PN junction leakage. Antistatic area design principles suppress static charge accumulation and static voltage generation. Such as equipment, instruments, tools do not use plastic, plexiglass, ordinary plastic bags.

1. Safety, quickly and effectively eliminate static charge has been generated, the use of anti-static wrist rope anti-static chairs, cars, box.

2. ground floor anti-static, anti-static terrazzo, anti-static flooring, laying ground network.

3. The station table, work chair, stool surface ESD protection materials should be used.

4. Human wear anti-static clothing, shoes, and other wrist.

5. Ground

a, anti-static work area must be safe and reliable anti-static grounding device, ground resistance of less than 4. Anti-static ground zero line connecting the power supply can not be, can not be shared with the lightning ground, using the power of the three-phase five-wire system, its ground can be used as anti-static ground.

b, countertops, ESD protection floor mats, chairs, stools, and other antistatic shall be connected to ground through a current limiting resistor, wristbands and ground should be connected to ground through the top surface of the table

Then, the table can not be grounded in series with each other.

c, anti-static work area grounding system, including limiting resistor and connection terminals should be connected reliably and has a current carrying capacity, current limiting resistor should be chosen to ensure that the leakage current is less than 5mA, the lower limit is taken as 1M Ω.

6. When the humidity is less than 60% shall be built in anti-static operating system.

7. The ionizer can not effectively discharge electrostatic charge of the case, it can be ionized through the positive and negative ions in the air to prevent the accumulation of charge on the neutralization and components and other objects, ionization capacity greater than 250V / s.

8. humidifier humidifier allows moist air flow to prevent static charge accumulation, this law does not apply; adversely affect the site after humidification.

9. Packing electrostatic sensitive devices should take protective packaging; packaging electrostatic sensitive devices must implement anti-static storage box, anti-static bag.

10. The transportation and storage SSD must be placed in an antistatic container (box, bag), and anti-static vehicles (cars). Treasury to meet the anti-static operating system requirements, SSD anti-static discharge shall

Container, storage and transportation position away from static electricity, electromagnetic or radiation field.

11, SSD components should be classified Handle electrostatic sensitive symbol symbolic accord GJB1649 regulations. E, anti-static materials of the measuring method and timeliness 1, triboelectric method: Cotton

120 beats / min 20 times. 2, resistivity measurements, less than 1010W as well. 3, when the attenuation constant of the RC red bag and a red foam valid for six months, not in the sun, black

Anti-static box 5 years, plastic tubes mounted IC, there timeliness. F, the production system problems on site

Electrical protection LED assembly quietly minimum requirements

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