What is the difference between clearance and creepage in PCB?

In the world of Printed Circuit Boards (PCBs), there are two important terms that engineers often come across - "clearance" and "creepage". These terms are related to safety and play a crucial role in determining the design and spacing between different components on a PCB. Although both terms are associated with the distance, they have distinct meanings and applications.

Clearance

Clearance refers to the shortest distance between two conductive parts on a PCB that is measured along the air or dielectric insulation. It ensures that a sufficient gap exists between sensitive or high-voltage components to prevent electrical arcing or short circuits. Clearance requirements vary based on the PCB's application and the voltage levels it handles. A larger clearance is necessary when dealing with higher voltage levels to minimize the risk of unintentional contact and electrical discharge.

Creepage

On the other hand, creepage refers to the shortest distance between two conductive parts on a PCB that is measured along the surface of the insulating material. Unlike clearance, creepage considers the path that the current may follow on the surface of the PCB due to moisture, dust, or dirt accumulation. Creepage is essential to prevent the formation of conductive paths that could lead to electrical discharge or leakage currents. In applications where environmental conditions may affect the PCB's performance or safety, designing appropriate creepage distances becomes crucial.

Application and Importance

The understanding and consideration of both clearance and creepage are vital in PCB design, especially for applications that involve high voltages or harsh environments. Ignoring these factors can result in significant safety risks, including component damage, electrical faults, and even fire hazards. Compliance with clearance and creepage requirements is typically mandated by safety standards and regulations applicable to specific industries.

By following proper clearance and creepage guidelines, the risk of electrical shock, short circuits, and other hazardous incidents can be minimized. PCB designers need to carefully analyze their design specifications, understand the voltage ratings and environmental conditions, and select appropriate insulation materials in order to ensure adequate clearance and creepage distances are maintained throughout the circuit board.