What is ESD and what damages can it cause?

We’re talking about Electrostatic Discharge (ESD) on this blog all the time. But what exactly does it mean and why is it so dangerous? Today’s post will answer those questions!

ELECTROSTATIC CHARGE

All matter is constructed from atoms. These atoms have negatively charged electrons circling the atom’s nucleus which includes positively charged protons. As the atom has an equal number of electrons and protons, it balances out having no charge. So far, so good!
The problem is that all materials can tribocharge or generate ElectroStatic charges. Most commonly, this happens through contact and separation – examples are:

  • Unwinding a roll of tape
  • Gas or liquid moving through a hose or pipe
  • A person walking across a floor and soles contacting & separating from the floor.

Generating an ElectroStatic chargeUnwinding a roll of tap can generate an electrostatic charge

The simple separation of two surfaces can cause the transfer of electrons between surfaces resulting in one surface being positively and the other one negatively charged. With that we’ve just generated an ElectroStatic charge!
The amount generated varies and is affected by materials, friction, area of contact and the relative humidity of the environment. At lower relative humidity, charge generation will increase as the environment is drier. Common plastics generally create the greatest static charges.

ELECTROSTATIC DISCHARGE (ESD)

If two items are at the same electrostatic charge or equipotential, no discharge will occur.
However, if two items are at different levels of ElectroStatic charge (i.e. one is positively and the other one negatively charged), they will want to come into balance. If they are in close enough proximity, there can be a rapid, spontaneous transfer of electrostatic charge. This is called discharge or ElectroStatic Discharge (ESD). Examples in daily life:

  • Lightning, creating lots of heat and light
  • The occasional zap felt when reaching for a door knob
  • The occasional zap felt when sliding out of a car and touching the door handle

Feeling the Zap when touching a doorknobHave you felt the zap before?

In a normal environment like your home, there are innumerable ESD events occurring, most of which you do not see or feel. It takes a discharge of about 2,000 volts for a person to feel the “zap”. It requires a much larger ESD event to arc and be seen (e.g. lightning). While a discharge may be a nuisance in the home, ESD is the hidden enemy in a high tech manufacturing environment. Modern electronic circuitry can be literally burned or melted from these miniature lightning bolts. ESD control is therefore necessary to reduce and limit these ESD events.

 TYPES OF ESD DEVICE DAMAGE

ESD damage to electronic components can lead to:

  • Catastrophic Failures
  • Latent Defects

Catastrophic Failure

Catastrophic failure causes a failure in an ESD sensitive item that is permanent. The ESD event may have caused a metal melt, junction breakdown or oxide failure. Normal inspection is able to detect a catastrophic failure.

Latent Failure

A latent defect can occur when an ESD sensitive item is exposed to an ESD event and is partially degraded. It may continue to perform its intended function, so may not be detected by normal inspection. However, intermittent or permanent failures may occur at a later time.

COSTLY EFFECTS OF ESD

A catastrophic failure of an electronic component can be the least costly type of ESD damage as it may be detected and repaired at an early manufacturing stage.
Latent damage caused by ESD is potentially costlier since damage occurs that cannot be felt, seen or detected through normal inspection procedures. Latent defects can be very expensive as the product passes all inspection steps and the product is completed and shipped. Latent defects can severely impact the reputation of a company’s product. Intermittent failures after shipping a product can be frustrating, particularly when the customer returns a product, reporting a problem which the factory again fails to detect. It consequently passes inspection and the product is returned to the customer with the problem unresolved.

ESD Damage to a PCB

The worst event is when the product is installed in a customer’s system, and performs for a while and then performs erratically. It can be very expensive to troubleshoot and provide repairs in this situation.
One study indicated the cost to be:

  • £7 Device
  • £7 Device in board – £700
  • £7 Device in board and in system – £7,000
  • £7 Device and system fails – £70,000

Industry experts have estimated average electronics product losses due to static discharge to range from 8 to 33%. Others estimate the actual cost of ESD damage to the electronics industry as running into the billions of dollars annually.

CONCLUSION

It is critical to be aware of the most sensitive items being handled in your factory. As electronic technology advances, electronic circuitry gets progressively smaller. As the size of components is reduced, so is the microscopic spacing of insulators and circuits within them, increasing their sensitivity to ESD. As you can predict, the need for proper ESD protection increases every day.
If you’re new to ESD and ESD Control, we suggest you read this article for more information on how to protect your ESD sensitive devices.

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About Vermason

Vermason is a manufacturer of ESD protection products and was founded in Letchworth in 1979. Our mission is to maintain our position as the primary ESD solutions provider for the electronics industry in Europe. Vermason strive to manufacture quality ESD Control products with innovation, leadership and partnerships which deliver long term commercial benefits. We understand the many challenges our customers face regarding quality and reliability. We support these requirements with products and services of exceptional value which help them gain competitive advantages in their markets. We also appreciate that the control of ESD is one of many necessary links in a long chain required to bring a customer’s project to a successful completion. We endeavour to make that happen. We sustain our vision and mission by constantly seeking renewal via continuous education, application of new technologies and good business practices. Employees are expected to serve the customer with the highest level of technical knowledge in the industry.

Posted on 2016-08-11, in Articles, ESD Information, Resources. Bookmark the permalink. 7 Comments.

  1. Bob Spearing

    Latent damage costs always amaze me, it’s certainly worth repeating – nice update, thanks

  2. bashir ali

    Very interesting information I never thought about it despite working as Biomedical engineer conducting repairs of circuitry of medical equipment. instrument and small devices.

  3. ESD damage to an electronic device or board can indeed be very expensive, but consider the cost of ESD affecting a photomask that is used to print the patterns for semiconductor chips. If a photomask is damaged and the defect is not detected it will print thousands upon thousands of potentially defective chips. More than a decade ago I was invited to help resolve a problem at a semiconductor foundry where electrostatic damage to a single critical photomask had cost them more than a million dollars in scrapped and lost output. Imagine what the cost would be today!

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