Differences and Selection between GPO-3, FR-4, and G10

Time: 08-19 2025 Auther: Ztelec group

1. Material Composition & Manufacturing Process GPO-3 (Glass fiber reinforced unsaturated polyester sheet) Base...

1. Material Composition & Manufacturing Process

GPO-3 (Glass fiber reinforced unsaturated polyester sheet)

Base: Glass fiber reinforcement

Resin system: Unsaturated polyester resin

Process: Molded sheet, with smooth or matte surface options

GPO3 insulation board

FR-4 (Glass cloth reinforced epoxy sheet, flame-retardant type)

Base: Glass cloth

Resin system: Epoxy resin with flame retardants

Process: Laminated sheet, mainly used for PCB

fr4 sheet

G10 sheet (Glass cloth reinforced epoxy sheet, non-flame-retardant type)

Base: Glass cloth

Resin system: Epoxy resin (without flame retardants)

Process: Laminated sheet, similar to FR-4 but without flame retardancy

g10 epoxy fiberglass sheet

2. Key Performance Comparison

Property	GPO-3	FR-4	G10
Thermal class	Class B (130℃) / Class F (155℃)	Class B (130℃) ~ Class H (180℃)	Class B (130℃)
Flame resistance	Excellent (UL94 V-0)	Excellent (UL94 V-0)	Non-flame-retardant (HB)
Electrical performance	Good, excellent arc resistance and tracking resistance	Excellent dielectric performance, suitable for high-frequency, high-speed signals	Good, but less stable than FR-4 at high frequency
Mechanical strength	High, especially impact resistance	High strength, excellent dimensional stability	High strength, slightly lower than FR-4
Moisture resistance	Excellent	Good, but performance may decline in long-term humid environments	Fair
Machinability	Easy to machine, cost-effective	Machinable, but mainly used in PCB etching and drilling	Machinable
Cost	Relatively low	Medium to high	Medium

3. Typical Applications

GPO-3

Transformers, switchgear, motor insulation partitions

Insulation supports, busbar supports, phase barriers in electrical equipment

Suitable for insulation and structural parts in medium- and low-voltage power systems

FR-4

Standard material for printed circuit boards (PCBs)

High-frequency, high-speed circuits, precision electronics

Also used in battery insulation sheets, electronic insulation spacers

G10

Mechanical structural parts, non-flame-retardant insulation parts

Military, aerospace components, knife handles, sports equipment

Suitable for high-strength applications without strict flame-retardant requirements

4. Selection Guidelines

Flame-retardant requirements

With flame-retardant requirement: choose FR-4 or GPO-3

Without flame-retardant requirement: G10 is cost-effective

Application field

Electrical insulation (transformers, switchgear): choose GPO-3

PCB, circuit substrate: choose FR-4

Mechanical structural parts, tool components: G10 is suitable

Operating environment

Humid/arc environment: GPO-3 performs better

High-frequency electronic signals: FR-4 is preferred

General insulation + strength: G10 is sufficient

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