1. Electrostatic discharge

Electrostatic discharge (ESD) is a well-known electromagnetic compatibility issue that can cause electronic equipment malfunction or damage. When semiconductor devices are placed separately or installed in circuit modules, even without power, they may cause permanent damage to these devices. Components that are sensitive to electrostatic discharge are called electrostatic discharge sensitive components (ESDS).

If the voltage between two or more pins of a component exceeds the breakdown strength of the component medium, it will cause damage to the component. This is the main reason for MOS device failures. The thinner the oxide layer, the greater the sensitivity of the component to electrostatic discharge. A fault usually manifests as a short circuit phenomenon where the component itself has a certain resistance value to the power supply. For bipolar components, damage generally occurs in the active semiconductor area separated by a thin oxide layer that has been metal sprayed, resulting in a path of severe leakage.

Another type of fault is caused by the temperature of the node exceeding the melting point of semiconductor silicon (1420 ℃). The energy of electrostatic discharge pulses can generate local heating, resulting in this mechanism of malfunction. Even if the voltage is lower than the breakdown voltage of the medium, this fault can occur. A typical example is that the breakdown between the emitter and base of an NPN type transistor can cause a sharp decrease in current gain.

After the device is affected by electrostatic discharge, functional damage may not occur immediately. These potentially damaged components are often referred to as' limps', and once used, they will exhibit greater sensitivity to future electrostatic discharges or conductive transients.

It is very important to pay close attention to the damage that occurs to components under imperceptible discharge voltages. When the static voltage reaches 2000 volts, the fingers feel it. When the voltage exceeds 3000 volts, sparks appear and the fingers feel prickly pain. When the voltage exceeds 7000 volts, people feel an electric shock. The static voltage generated in daily life can sometimes reach tens of thousands of volts. However, due to the extremely short time of friction electrification and the small amount of current generated, it generally does not pose a risk to human life. However, when electronic components are damaged, the voltage is only a few hundred volts, and sensitive devices are only a few volts.

The harmful effects of electrostatic discharge were recognized in the 1970s, due to the development of new technologies that have made components increasingly sensitive to damage caused by electrostatic discharge. The losses caused by electrostatic discharge can reach over several million dollars per year. Therefore, many large component and equipment manufacturers have introduced professional technology to reduce the accumulation of static electricity in the production environment, thereby greatly improving the product qualification rate and reliability. Users have also understood the importance of preventing and controlling electrostatic discharge damage based on their own experience.

How to deal with electrostatic discharge?

The first step in controlling the accumulation of static electricity is to understand the mechanism of static charge generation.

Electrostatic voltage is generated by the contact and separation of different types of substances. Although friction can accumulate more charges, friction is not necessary. This effect is known as frictional electrification, and the voltage generated depends on the characteristics of the materials that are rubbing against each other. The friction electrification sequence list lists the difficulty of electrification of various substances. For two substances that come into contact with each other, electrons will shift from the substance at the top of the sequence table to the substance at the bottom, causing both substances to carry positive and negative charges respectively. The farther apart the substances in the sequence table are, the greater the amount of charge they each carry. The friction electrification sequence of common substances is shown in Table 1.

1. Electrostatic discharge

Electrostatic discharge (ESD) is a well-known electromagnetic compatibility issue that can cause electronic equipment malfunction or damage. When semiconductor devices are placed separately or installed in circuit modules, even without power, they may cause permanent damage to these devices. Components that are sensitive to electrostatic discharge are called electrostatic discharge sensitive components (ESDS).

If the voltage between two or more pins of a component exceeds the breakdown strength of the component medium, it will cause damage to the component. This is the main reason for MOS device failures. The thinner the oxide layer, the greater the sensitivity of the component to electrostatic discharge. A fault usually manifests as a short circuit phenomenon where the component itself has a certain resistance value to the power supply. For bipolar components, damage generally occurs in the active semiconductor area separated by a thin oxide layer that has been metal sprayed, resulting in a path of severe leakage.

Another type of fault is caused by the temperature of the node exceeding the melting point of semiconductor silicon (1420 ℃). The energy of electrostatic discharge pulses can generate local heating, resulting in this mechanism of malfunction. Even if the voltage is lower than the breakdown voltage of the medium, this fault can occur. A typical example is that the breakdown between the emitter and base of an NPN type transistor can cause a sharp decrease in current gain.

After the device is affected by electrostatic discharge, functional damage may not occur immediately. These potentially damaged components are often referred to as' limps', and once used, they will exhibit greater sensitivity to future electrostatic discharges or conductive transients.

It is very important to pay close attention to the damage that occurs to components under imperceptible discharge voltages. When the static voltage reaches 2000 volts, the fingers feel it. When the voltage exceeds 3000 volts, sparks appear and the fingers feel prickly pain. When the voltage exceeds 7000 volts, people feel an electric shock. The static voltage generated in daily life can sometimes reach tens of thousands of volts. However, due to the extremely short time of friction electrification and the small amount of current generated, it generally does not pose a risk to human life. However, when electronic components are damaged, the voltage is only a few hundred volts, and sensitive devices are only a few volts.

The harmful effects of electrostatic discharge were recognized in the 1970s, due to the development of new technologies that have made components increasingly sensitive to damage caused by electrostatic discharge. The losses caused by electrostatic discharge can reach over several million dollars per year. Therefore, many large component and equipment manufacturers have introduced professional technology to reduce the accumulation of static electricity in the production environment, thereby greatly improving the product qualification rate and reliability. Users have also understood the importance of preventing and controlling electrostatic discharge damage based on their own experience.

How to deal with electrostatic discharge?

The first step in controlling the accumulation of static electricity is to understand the mechanism of static charge generation.

Electrostatic voltage is generated by the contact and separation of different types of substances. Although friction can accumulate more charges, friction is not necessary. This effect is known as frictional electrification, and the voltage generated depends on the characteristics of the materials that are rubbing against each other. The friction electrification sequence list lists the difficulty of electrification of various substances. For two substances that come into contact with each other, electrons will shift from the substance at the top of the sequence table to the substance at the bottom, causing both substances to carry positive and negative charges respectively. The farther apart the substances in the sequence table are, the greater the amount of charge they each carry. The friction electrification sequence of common substances is shown in Table 1.