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GPO-3 is an excellent insulating material, great indoors and under cover.

What's the Difference Between Epoxy and Polyester? (Laminating Plastics for G10 and GPO-3)


The performance behind G10 and GPO-3 insulating material’s laminating plastic will help you understand why they are specified for different tasks. Here are several important differences between the epoxy used to laminate G10 and the polyester resin used to laminate GPO-3.

G10, which is laminated with epoxy, was originally designed for printed circuit boards and that's where it gets its designation G10 (G10-FR4 part shown).

Bonding Strength
Epoxy is known for its bonding capabilities. Epoxy can hold up to 2,000 lbs. per sq. in., while polyester resin is less than 500 lbs. per sq. in.

Wear Resistance
Epoxy is resistant to peeling, cracking and resistance to chemicals and environmental exposure. Polyester is much more fragile and used for temporary fixes and low-stress applications.

Cost Comparison
Epoxy is more expensive than resin, due to its formulation requirements.

Moisture Resistance
Epoxy is moisture resistant, and can even be used underwater. Polyester resin is considered water-permeable.


GPO-3 is an excellent insulating material, great indoors and under cover; just not exposed to the elements and corrosive environments.

Cure Time
Depending on the formulation and temperature, resin generally has a faster cure time. Lowering or raising the ambient temperature can change both products’ cure time. Some epoxy formulations can be used at extreme temperatures.

Odor
Although it sets up much faster, polyester can stink enough to inflame your nose! Use outside or with specified ventilation and protection filters when applying both epoxies and resins.

Shelf Life
Epoxy has a much longer shelf life than polyester. If it hasn’t been mixed, epoxy can last for many years without losing its potency. Resin is more fragile over time.

Now you know a bit more why GPO-3 may be less expensive but also used for less demanding applications and why G10 is just about indestructible and that sometimes the price reflects that.

Monti Inc. is a custom G10 and GPO-3 electrical insulation material fabricator, and copper fabrication manufacturer that has the expertise to produce complex electrical component fabrications to the tightest tolerances and highest quality control. We'll also help you value engineer your part to shorten lead times while increasing the value of the component.