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The ultimate guide to ESD damage solution in electronics manufacturing

The ultimate guide to ESD damage solution in electronics manufacturing

The scale of modern semiconductor devices is getting larger and larger, and the working voltage is getting lower and lower, which leads to the sensitivity of semiconductor devices to external electromagnetic interference is also greatly improved.

More and more attention has been paid to the problems caused by ESD, such as circuit interference, ESD damage to components, CMOS circuits and interface circuits. ESD of electronic equipment has also been written into national and international standards as an important content of electromagnetic compatibility test.

What is ESD damage?

What is ESD damageEDS is the transfer of electrostatic charge between two objects with different electrostatic potentials due to direct contact or electrostatic induction. After the energy of the electrostatic field reaches a certain range, the phenomenon of discharging through the medium is electrostatic discharge.

ESD occurs when an object short circuited to ground is exposed to electrostatic field. The potential difference between two objects will cause the discharge current to transmit enough electricity to offset the potential difference. This high-speed power transmission process is called ESD.

In this process, potential damage voltage will be generated. Current and electromagnetic fields. ESD will generate strong spike pulse current, which contains rich high-frequency components. Its upper limit frequency can exceed 1GHz, depending on the level. Relative diffuse humidity. Near the velocity and shape of the discharge object. At this frequency, the routing of typical equipment cables or even printed boards will become very effective receiving antennas.

Therefore, for typical analog or digital electronic equipment, ESD tends to induce high-level noise, which will cause serious damage to electronic equipment or abnormal operation.When the ESD position is close, both the current and magnetic field are strong. Therefore, the circuit near the ESD location will be generally affected.

What is ESD in SMT?

ESD is a type of electrical discharge that can occur between two objects with differing charges. This can happen when one object is grounded and another is not, or a large amount of static electricity builds up on the surface of an object and then suddenly dissipates into another object.
This can cause problems for SMT because SMT components are held down by solder bumps, which have a charge of their own. If the bumps have no charge, they can attract static electricity from ESD and create more problems than they solve.

How ESD affect PCB?

Electrostatic discharge (ESD) can be a serious problem for PCBs. It is caused by the buildup of static electricity on the surface of a component, which can then be transferred to other components or even the PCB itself when it is touched. ESD destroys electronic components and causes damage to wiring as well.There are several ways that ESD can affect a PCB:

● It will damage the insulation on wires and capacitors, which may cause leakage and short circuits in your system.

● The static buildup will cause cracks in solder joints between components or connectors, which can lead to intermittent or permanent failures of the device.

● If ESD builds up on a component’s surface long enough, it can actually lift off part of its silver paste coating layer! This leaves bare copper underneath, which will oxidize quickly if left exposed to air—which could result in corrosion or worse yet: bare conductive surfaces!

● ESD easily absorbs fine dust, causing certain pollution

● ESD will cause device breakdown. Electrostatic discharge is a process of charge accumulation. When the charge accumulates to a certain extent, when a device approaches it, electrostatic discharge will cause certain damage to the device, thus reducing the reliability of the device.

● ESD will cause electronic interference because it will radiate a lot of radio waves with frequency, which will affect the normal operation of surrounding devices.

What are two types of damage that can be caused by ESD?

Catastrophic failures are the most common type of ESD damage. They happen when static electricity builds up in the air between two objects, causing them to touch each other. This can happen when you touch a grounded object to a non-grounded object, such as your phone touching your shirt.
Latent defects are also common types of ESD damage. Latent defects are defects that are not visible when an item is assembled but become visible after assembly has begun. Latent defects include cracks in the solder joint between parts, or small scratches on parts’ surfaces.

How can ESD damage be prevented?

ESD damage can be prevented by taking following precautionary measures.
How can ESD damage be prevented

Component layout design

The damage of ESD on PCB is mainly manifested in the damage of ESD to PCB and components when external interfaces are plugged in. Therefore, the component layout of PCB is particularly important, especially the layout of ESD components (TVS tubes, LC filters, ferrite beads, high-voltage capacitors, etc.).

(1) Layout of sensitive components: keep sensitive components such as MCU and crystal oscillator away from the board edge as far as possible and away from the source of electrostatic discharge (external interface);

(2) The layout of sensitive circuits: the reset circuit and other sensitive circuits shall be kept away from the board edge as far as possible to prevent the abnormal reset of the system due to electrostatic interference;

(3) Layout of ESD components: for signal lines, the layout is: connector → ESD components → matching resistance → MCU; For the power line, the layout is: power connector → TVS tube → filter → capacitor → rear load.

Wiring design

The wiring must follow the principle that after the signal comes in from the connector, it must first pass through the ESD element and then enter the MCU element or other circuits, and it is better not to change the layer of the wiring from the connector to the ESD element (this is why the connector and the ESD element are placed on the same side), it is the USB wiring method, and other signals can refer to this wiring method.

Note that the ground of ESD components should be paved with copper (or the wiring should be thick), and then more holes should be drilled to the ground plane. The wiring of analog signal, high-speed signal, high-frequency signal, clock signal and other key signals shall not be close to the ESD component pin or directly below the ESD component. The area of the loop formed by the wiring of all signal lines shall be as small as possible, and shall not be close to the edge of the PCB board.

Paving design

The flooring also plays a great role in ESD protection, and the flooring design should be paid attention to in PCB design.
1. When multilayer boards are used, there should be at least one complete stratum to ensure that important signals can be coupled with the ground, which can also enable the ESD current to be smoothly coupled to the low impedance ground, protect the key signals and reduce the signal loop area.
2. Connector paving: pave the area around the connector
Blank area paving: after PCB wiring is completed, in order to increase the drainage area of the ground, pave the ground at the spare place of the PCB, and ensure that each piece of copper paved is connected to the ground via the ground, and ungrounded copper blocks are prohibited

What is the difference between ESD and antistatic?

Antistatic and ESD are two terms that often get used interchangeably, but they’re actually quite different.
ESD stands for electrostatic discharge, which is the kind of static electricity that can cause damage to electronics and other sensitive equipment if it builds up inside them. Antistatic is a material that prevents static from building up inside electronic devices, so these devices remain safe from ESD damage.

FAQ about ESD damage

How does ESD damage electronics

How does ESD damage electronics?

ESD damage to electronics can happen in a variety of ways and from a number of different sources. The most common way that ESD can damage electronics is by inducing direct current (DC) into the device, which causes it to fail. This can happen when you touch the device with ESD-sensitive components like a finger or an ESD mat, or place the device on an ESD-sensitive surface.

Another common cause of ESD damage is electrostatic discharge (ESD), which is generated when there are no conductive paths to the ground.

What is ESD voltage?

ESD voltage is not a thing. It’s a term used to describe the amount of electricity that flows through your body when you touch something metal.

ESD voltage is also called “electrostatic discharge,” and it can be dangerous when it happens in an uncontrolled environment. When you’re working on a circuit board, and your body touches the metal surface of the board, you are exposed to this dangerous voltage.

Conclusion

Although ESD is terrible, it may even bring serious consequences. However, only by correctly understanding the ESD damage and taking measures to protect the power and signal lines on the circuit, can ESD current be effectively prevented from flowing into the PCB.

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