Saturday, May 7, 2011

【 Weak current College 】 LED basics of EOS and ESD difference 】

I. What is EOS?

Abbreviation for ElectricalOverStress EOS, means all of excessive electrical stress. While current or voltage exceeds the maximum standard devices, device performance can weaken or even damage.

EOS is usually derived from the

1. power supply (AC/DC) noise interference, power and voltage.

2. as a result of the test program switch (hot swap) cause of transient current/peak/low-frequency interference. The process duration may be a few microseconds to several seconds (or possibly a few nanoseconds), very short EOS pulse resulting damage and ESD damage similar.

3. lightning.

4. test procedure caused by transient/switch glitch/short pulse wave interference.

5. testing poorly designed, for example, when the device is not powered on or has exceeded its limit of the operation to send a test signal devices. Another example of the power supply to the device by adding a test signal, or exceeds the maximum operating conditions.

6. from the other device of pulse signal interference from other devices send pulses.

7. inappropriate work steps, the workflow does not have a reasonable

8. Earth point rebound (due to insufficient bonding lead current fast conversion caused high voltage)

2. What is ESD?

The ESD is in English, Chinese ElectricalStaticDischarge release for electrostatic discharge. Charge transfer from one object to another object. Static electricity is an objective of natural phenomena, produces a variety of ways, such as contacts, friction, etc. Static electricity is characterized by a high voltage, low power, low-current and act only for short periods. Body's own actions or contact with other objects, separation, friction or induction and other factors, can produce several kilovolt even tens of thousands of volts of static electricity. Electrostatic in multiple areas causing serious harm. Frictional electrification and body static electricity is the electronic industry's two great harm. Electrostatic protection during production of the main measures for electrostatic dissipative, disclosure, and, in the humidifier, shielding and grounding. Human body static electricity protection system has an antistatic wrist strap, ankle band, work clothes, footwear, hats, gloves or finger, etc, with electrostatic leaks, and with the shield, and other functions. Electrostatic protection work is a long-term project, any errors or omissions of, will result in the failure of electrostatic protection work.

Third, the contrast is the difference between


Typically, from power generation and testing equipment
ESD is a special case of EOS, limited energy, caused by electrostatic charge

Event duration in microseconds ~ nanosecond. (Or possibly nanoseconds)
Event duration in the picosecond ~ nanosecond level

Corruption including wire melting, fever, high power, latch-up effect
Its visibility is not strong damage location difficult to find,

Short of EOS pulse damage looks like ESD damage
Often resulting in damage to the Crystal level.

IV. electrostatic protection

1. set the static area

Description: set in the production site, electrostatic sensitive area and you want to do the obvious warning signs, gives in to everyone's attention.

2. electrostatic regional considerations

A. operators should wear anti-static wrist strap, should wear anti-static clothing, shoes, scarves, Chair should set anti-static set. (Side of human contact, on the other side and ground wire)

B. may place the PBA of the area you want to paste antistatic cloth, and you want to join anti-static grounding clip.

C. all static region of electrostatic cannot exceed 100V static region of the container should use anti-static materials, if the static region of electrostatic voltage exceeding 100V, this is going to ion fan should be used to eliminate surface anti-static. Note: do not place the antistatic range and production activities not related to the goods.

3. the relative humidity should be 50-60%

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