FR-4 fiberglass Sheet thickness and application selection guide

FR-4 Common Thickness Range FR-4 for PCB substrates: 0.2 mm – 3.2 mm (1.6 mm is the most common standard PCB thickne...

FR-4 Common Thickness Range

FR-4 for PCB substrates: 0.2 mm – 3.2 mm (1.6 mm is the most common standard PCB thickness)

FR-4 sheets for insulation and structural parts: 0.5 mm – 5 mm (can be customized to thicker sizes, even 10 mm+)

Ultra-thin types: 0.1–0.4 mm (used in flexible/rigid-flex boards, requires special processes)

Thickness vs. Typical Applications

Key Factors for Selection

Mechanical Strength Requirements

For heavy components and vibration resistance → choose thicker boards (≥1.6 mm)

For lightweight, portable devices → choose thinner boards (≤0.8 mm)

Insulation & Dielectric Strength

FR-4 dielectric strength is about 20 kV/mm; greater thickness provides higher insulation margin.

For high-voltage insulation, ≥2 mm thickness is recommended, and creepage distance should be calculated.

Processing & Cost

1.6 mm is the most common standard, with stable supply and low price.

Non-standard thicknesses may increase cost and lead time.

Thermal Performance

For high-temperature applications (reflow soldering, long-term >110°C), choose High-TG (≥150°C) FR-4.

Electrical Performance

For high-frequency or high-speed circuits, consider Dk/Df parameters in addition to thickness.

Quick Selection Tips

For PCB mainboards: 1.6 mm preferred (adjustable to 1.0–2.0 mm for special designs)

For high-voltage insulation supports: 2.0–5.0 mm (or even thicker)

For ultra-thin wearables or small modules: 0.4–0.8 mm

For high mechanical stress & power components: 2.0–3.2 mm