Electrostatic Discharge (ESD) is a silent threat to electronic devices, especially in industrial and automation sectors where PCBAs (Printed Circuit Board Assemblies) are the backbone of equipment. A single ESD event, with voltages reaching thousands of volts, can damage sensitive components, cause unexpected downtime, and increase production costs. For small and medium-sized industrial equipment manufacturers and procurement engineers, integrating robust ESD protection into PCB layouts isn’t just a design choice—it’s a critical step to ensuring product reliability and reducing warranty claims. In this blog, we’ll break down what ESD is, how it impacts PCBs, and 6 practical ESD protection methods to implement in your next PCB design.
What Exactly Is ESD?
ESD occurs when two charged materials come into contact, short-circuit, or experience dielectric breakdown, resulting in a sudden flow of current to balance their electrical charges. This can happen due to triboelectric charging (friction between materials) or electrostatic induction. For consumer and industrial products, ESD typically triggers air dielectric breakdown when the electric field between two points exceeds 40 kV/cm—though factors like humidity, temperature, and air pressure can alter this threshold. High humidity, for example, increases air conductivity, dissipating some charges and raising the voltage required for ESD.
Figure 1ESD
How ESD Harms PCBs
While static electricity is common in daily life, its high voltage can generate massive current pulses when discharged. These pulses dissipate intense heat in PCB components and conductors, leading to irreversible damage. Two critical areas are most vulnerable:
– Integrated Circuits (ICs): Modern ICs, manufactured with fine lithography, can’t withstand high voltage drops. ESD pulses force current through IC dies, creating heat that destroys semiconductor structures.
– Connectors: Connectors aren’t ESD sources, but they accumulate static charges. Plugging in cables, pressing buttons, or floating pins (due to charge transfer on floating conductors) can trigger ESD sparks. Metal shields on connectors are also common ESD hotspots.
The solution for floating pins? Ground them. Shielded connectors should have low-impedance ground connections to the chassis (not via capacitors or PCB traces) to direct ESD currents safely to earth.
Figure 2Integrated Circuits (ICs)
Key ESD Protection Circuit Designs
1. TVS Diodes & Diode Circuits
Transient Voltage Suppressor (TVS) diodes are the most widely used ESD protection in low-voltage industrial setups. They offer higher voltage clamping than built-in IC protection. Common configurations include:
– Unidirectional TVS Diodes: Act as open circuits during normal operation. During positive ESD cycles, they enter avalanche mode to shunt current to ground; during negative cycles, they conduct forward-biased.
– Bidirectional TVS Diodes: Protect against both polarities. In positive ESD cycles, one diode conducts forward-biased while the other operates in avalanche mode; roles reverse in negative cycles, ensuring consistent current shunting.
Figure 3ESD protection in low-voltage
2. TISP4350 Overvoltage Protectors
For telecom lines and industrial circuits, TISP4350 protectors replace TVS diodes, offering versatile defense against ESD and other overvoltage events. Choose models based on voltage range, operating voltage, response time, and event duration.
Figure 4TISP4350 Overvoltage Protectors
3. Other ESD Suppressors
Multilayer varistors, gas discharge tubes (GDTs), and polymer-based suppressors are alternatives. These components shunt ESD currents to ground, clamping voltages below damaging levels. Refer to datasheets for circuit integration examples.
4. GDT + TVS Diode Combo
For high-voltage scenarios, pair GDTs with TVS diodes and inductors. The inductor and TVS form a low-pass RL filter, slowing ESD pulse rise time. A fuse at the input adds extra protection against extreme voltages.
Figure 5GDT + TVS Diode Combo
6 ESD Protection Methods for PCB Layouts
1. Optimize Impedance Around TVS: Minimize parasitic inductance (L1-L3) between ESD sources, TVS, and ground. Ensure inductance between TVS and protected ICs (L4) is larger than L1-L3 to divert current to ground.
2. Strategic TVS Placement: Position TVS diodes as close to ESD sources (e.g., USB ports) as possible. Longer traces between TVS and ICs reduce ESD pulse energy.
3. Proper Via Usage: Keep ESD sources and TVS on the same layer. Avoid vias between them—if unavoidable, route ESD currents through TVS before vias to protected circuits.
4. Minimize Via Coupling: Avoid vias between ESD sources and suppressors, as they increase trace inductance and EMI. If vias are necessary, place them after the TVS.
5. Low-Impedance Grounding: Connect TVS ground pins directly to ground planes via multiple vias. Use larger drill diameters for vias to counteract skin effect and fill them with non-conductive material to maintain surface area.
6. Shield & Ground Connectors: Ensure connector shields have direct chassis ground connections to prevent ESD buildup on metal parts.
Why Partner With Us for Your PCBA Needs?
At our PCBA manufacturing facility, we specialize in integrating these ESD protection best practices into every design—from circuit schematic to final assembly. Our team works closely with industrial equipment manufacturers to tailor PCBAs that meet strict reliability standards, reducing ESD-related failures and downtime. Whether you’re designing automation controllers, sensor modules, or industrial IoT devices, we deliver high-quality, ESD-protected PCBs that keep your equipment running smoothly.
