Did you hear a "crackling" sound when taking off your sweater in winter or get an "electric shock" when touching the door handle? This is the most common electrostatic discharge (ESD) phenomenon in daily life. What seems like a tiny static electricity can be a "fatal killer" for electronic devices - the malfunction of mobile phone screens, the false triggering of sensors, and the burning of chips are often closely related to ESD.

Today, let's start from the basics to understand the essence and hazards of ESD, as well as how to verify the protective effect through testing. As a seasoned manufacturer in the ESD protection field, Shanghai Leiditech will also share practical industry experience in this article.

1、Electrostatic Discharge: The Invisible "Electronic Killer"

Static electricity is the static charge accumulated on the surface of an object. When objects with opposite charges approach or come into contact, the charges will transfer instantaneously, forming a discharge. This is ESD. Don't underestimate this process: When the human body is charged and comes into contact with electronic devices, the ESD voltage can reach several thousand volts. However, the insulation layer of today's chips is only a few nanometers thick and simply cannot withstand such an impact.

Where does static electricity come from?

The core reason is "charge transfer". When two different materials rub against, come into contact with or separate (such as when plugging or unplugging a USB cable or when a plastic casing rubs against each other), electrons will move from one material to the other. The farther a material is located in the "triboelectric sequence", the more charges it transfers and the stronger the static electricity it generates.

• Why must ESD protection be emphasized now?

  The process miniaturization of semiconductor devices is a "double-edged sword". On the one hand, it follows the law of transistor scaling: as chip processes become increasingly advanced (such as 7nm, 5nm), the size of transistors is reduced to 1/k, and their area, power consumption, and latency are respectively reduced to 1/k², 1/k, and 1/k, significantly enhancing the performance of the devices. On the other hand, process miniaturization will lead to a proportional reduction in the thickness of the insulating film (such as the SiO₂ insulating film commonly used in silicon semiconductors). Since the dielectric strength of SiO₂ is 8-10 mV /cm (constant value), the reduction in the thickness of the insulating film will directly cause a synchronous decline in its withstand voltage capacity, significantly increasing the sensitivity of semiconductor devices to ESD. The insulation layer is getting thinner and thinner, and its ESD resistance has dropped significantly.

   

  In addition, the miniaturized design of electronic devices makes the internal component layout denser, and the electric and magnetic field interference generated by ESD is more likely to spread. Smartphones, Internet of Things devices and other equipment that require frequent plugging and unplugging of interfaces (such as USB, Type-C, etc.) have increased the probability of ESD shock several times compared to ten years ago. The superimposition of multiple factors makes ESD protection an indispensable key link in the design of electronic devices, and adding ESD protection diodes is currently one of the most mainstream and effective protection solutions.

  2、ESD testing: The "Touchstone" of Protection Effectiveness

  To verify whether ESD protection is reliable, standardized tests must be passed. At present, the commonly used testing systems in the industry are divided into two categories: "device-level" and "system-level". All ESD protection diodes of Leiditech have undergone strict testing. Leiditech EMC personnel are fully involved in the control of the testing process to ensure that the products meet various application requirements.

  2.1. Device-level testing: Simulating production scenarios

  • Human Body Model (HBM) : It simulates the discharge when a worker comes into contact with a chip while powered on (such as taking an unpackaged IC). The testing standard is JEDEC JESD22-A114, and the qualification threshold is usually 2500V-8000V.
  • Machine Model (MM) : Simulates the discharge of charged contact devices in automated equipment (such as surface mount technology (SMT) machines, tested in accordance with the JEDEC JESD22-A115 standard, which is more stringent than HBM.
  • Charged-Device Model (CDM) : It simulates the discharge of a chip when it comes into contact with a grounded circuit board after being charged (for example, when taking the chip from a material tray). The test standard is JEDEC JESD22-C101, which examines the device's instantaneous shock resistance capability.
   

2.2. System-level testing: Simulate user scenarios

• IEC 61000-4-2: The most commonly used system-level ESD test, which is divided into "contact discharge" (directly touching the metal interface) and "air discharge" (close to the coated housing). Generally, for consumer electronics, contact discharge ±8kV and air discharge ±15kV are required. All the ESD/TVS diodes of Leiditech have passed the test of this standard, and some models can reach contact discharge ±30kV.

• • IEC 61000-4-5: Simulating surges (high current pulses) generated by lightning strikes or power switches, with a test waveform of 8/20μs (8μs rises and 20μs drops to half). The Shanghai Leiditech high-power series can withstand peak currents of over 100A, providing maximum protection.

Summary

Although ESD is small, its destructive power is significant. Especially in today's era of miniaturization and high-frequency electronic devices, protection has become a necessity. As a professional manufacturer in the ESD protection field, Shanghai Leiditech’s EMC team, with their rich industry experience, often answers customers' questions and helps them understand the generation mechanism and testing standards of ESD, which is the first step to doing a good job in protection.

In the next article, the EMC guy from Leiditech will focus on the "core weapon of ESD protection" - the ESD protection diode. He will disassemble the internal structure and working principle of ESD and see how it "overcomes hardness with flexibility" to mitigate static electricity shock

Follow the official account of Leiditech Electronics to get more ESD protection tips and practical cases shared by Leiditech EMC guys.

Shanghai Leiditech Electronics is committed to becoming a leading brand in electromagnetic compatibility solutions and component supply, offering products such as ESD, TVS, TSS, GDT, MOV, MOSFET, Zener, inductors, etc. Leiditech has an experienced R&D team that can provide personalized customization services based on customer needs and offer the most superior solutions to customers.