The difference between LED EOS and ESD

First, what is EOS?

EOS stands for Electrical Over Stress and refers to all over-stress. When the external current or voltage exceeds the maximum specification of the device, the device performance will be weakened or even damaged.

EOS usually arises from

1. Power (AC/DC) interference, power noise, and overvoltage.

2. Transient current/peak/low-frequency interference due to test program switching (hot switching). The duration of the process may be a few microseconds to a few seconds (which may be a few nanoseconds), a very short EOS pulse damage and ESD damage similar.

3. Lightning.

4. Test transients/glitchs/glitches caused by program switching.

5. The test design is poor, for example, sending a test signal to the device when the device has not been powered up or has exceeded its upper operating limit. Another example is to test the signal before adding power to the device, or exceed the maximum operating conditions.

Pulsed signal interference from other devices, ie, pulses sent from other devices.

7. Inappropriate working steps, the workflow is not very reasonable

8. Ground point rebound (due to insufficient grounding lead to rapid current conversion caused by high voltage)

Second, what is ESD?

ESD is the reduction of English Electrical Static Discharge, and the Chinese interpretation is electrostatic discharge. Charges are transferred from one object to another. Electrostatic is an objective natural phenomenon, produced in many ways, such as contact, friction and so on. Electrostatic is characterized by high voltage, low battery, small current and short duration of the characteristics. The human body's own actions or contact with other objects, separation, friction or induction and other factors, can produce thousands of volts or even tens of thousands of volts of static electricity. Static electricity in many areas cause serious harm. Friction electrification and human static electricity are two major hazards in the electronics industry. The main measures for electrostatic protection in the production process are electrostatic leakage, dissipation, neutralization, humidification, shielding and grounding. Human body electrostatic protection system mainly anti-static wrist band, ankle strap, overalls, shoes and socks, caps, gloves or finger sets and other components, with electrostatic leakage, neutralization and shielding functions. Anti-static protection is a long-term system project. Any errors or omissions in any aspect will lead to the failure of electrostatic protection work.

Third, compare the difference

EOS

ESD

Typically generated by the power supply and test equipment

ESD is a special case of EOS, limited energy, caused by electrostatic charge

The duration of the event is in microseconds to seconds. (It may be in nanoseconds.)

The duration of the event is in the order of picoseconds to nanoseconds

Damages include metal wire melting, heating, high power, latch-up effects

Its visibility is not strong damage to the location is not easy to find,

Short EOS pulse damage looks like ESD damage

It usually leads to transistor-level damage.

Fourth, electrostatic protection

1. Set static area

Explanation: Set electrostatic sensitive areas on the production site, and make obvious warnings so that everyone on the site can pay attention.

2. Precautions in the static area

a. Operators should wear anti-static wrist straps, should wear anti-static clothing, shoes, scarves, chairs should be set of anti-static sleeve. (One end is in contact with the human body, and the other end is connected to the ground)

b. Anti-static tablecloths should be placed in the area where the PBA may be placed, and anti-static grounding buckles must be connected.

C. Electrostatic field of all items static electricity can not exceed 100V Static area of the container should be anti-static material, if the static area of the article electrostatic voltage exceeds 100V, this is the use of deionized fan surface static elimination of the object. Note: Anti-static area can not be placed in the production of unrelated items.

3. Humidity should be about 50% to 60%