FR4 Epoxy Sheet Thickness Selection

How to Choose the Right Thickness of FR4 Epoxy Sheet? The thickness of FR4 epoxy sheet is usually determined by appl...

How to Choose the Right Thickness of FR4 Epoxy Sheet?

The thickness of FR4 epoxy sheet is usually determined by application scenario, electrical requirements, mechanical strength, and processing method.

I. Common Thickness Range

Thin sheets: 0.2 mm – 3 mm

Mainly used for electrical insulating spacers, PCB substrates, and electronic isolation sheets.

Medium sheets: 3 mm – 10 mm

Common in transformer insulation parts, generator slot wedges, and structural supports.

Thick sheets: 10 mm – 50 mm or thicker

Used for switchgear busbar supports, RMU insulating parts, large motor end support rings.

II. Key Selection Criteria

Electrical Requirements

High-voltage insulation → recommend ≥3 mm, with extra safety margin based on dielectric strength.

PCB / circuit boards → standard thickness 0.8 mm, 1.0 mm, 1.6 mm.

Mechanical Strength

For insulation only → thin sheets are sufficient.

For insulation + structural load → thick sheets (≥5 mm) recommended.

Processing & Assembly

Complex shapes → thin sheets are easier for cutting, punching, drilling.

High-strength components → thick sheets require CNC or hot pressing.

Operating Environment

High temperature (130–155℃) → thicker sheets with high dimensional stability.

Outdoor / humid → medium-thickness sheets with low water absorption FR4 material.

III. Reference Table

Low-voltage / electronics → thin sheets

High-voltage / heavy load → thick sheets

Outdoor / high temp / humid → medium-thickness + modified FR4