Application Guidance for G10 Epoxy Sheet and 3240 Epoxy Sheet

Many customers face material‑selection challenges when comparing 3240 and G10 epoxy‑fiberglass laminates. Though both fall under the category of glass‑reinforced epoxy insulation materials, questions frequently arise regarding their functional equivalence and substitution.

Generally speaking, Grade 3240 is a cost‑effective laminate manufactured in accordance with China GB national standards. G10 is a high‑grade premium material built to NEMA requirements, intended for different industrial applications. They differ in base material, stability, temperature resistance and application scenarios.Therefore, the selection between 3240 and G10 should be based on a careful evaluation of the specific performance requirements,

Comparison of Key Performance Characteristics

The 3240 epoxy laminate adopts an epoxy-phenolic resin matrix, which is produced through the copolymerization and modification of phenolic resin and epoxy resin. After curing, it forms a three-dimensional cross-linked network structure that combines the high-temperature resistance of phenolic resin and the excellent adhesion and mechanical strength of epoxy resin.

G10 epoxy laminate conforms to United States NEMA standards. It is formulated with pure bisphenol‑A epoxy resin, yielding a denser microstructure and homogenous glass‑fiber dispersion. Compared with 3240, its superior substrate purity inherently delivers better electrical stability and mechanical toughness.

The 3240 epoxy laminate has relatively high water absorption. When exposed to humid environments, its dielectric performance sees moderate degradation, so it is most suitable for indoor applications in dry locations. G10 has ultra-low water absorption, and its dielectric and insulation properties remain stable even under high humidity, oil contamination and damp condition. This makes G10 ideal for harsh outdoor or marine environments where moisture resistance is critical.

3240 has a continuous service temperature rating of 130 °C for standard equipment operation. G10 is in a higher thermal class and provides excellent resistance to high-temperature creep, which can reduce deformation under long-term heavy loads. In addition, it has outstanding cryogenic compatibility and can withstand ultra-low temperature exposure, which is a functional advantage that 3240 does not have.

3240 has moderate hardness, and delamination may occur when it is subjected to heavy mechanical loads. G10, by contrast, features improved fracture toughness and a compact laminated structure. It delivers good resistance to cracking, surface fuzzing and delamination during precision drilling and milling processes. Its enhanced vibration tolerance and load-bearing capacity also make it suitable for high-precision machining operations.

When should you choose 3240 versus G10?

3240 is suitable for domestic conventional electrical apparatus, high‑/low‑voltage switchgear assemblies, general‑purpose power transformers, motor insulation components, standard EV‑charging insulating parts and high‑volume manufacturing projects.It is the preferred option for conventional that require basic reliability, cost control and moderate performance.

Owing to its outstanding fracture toughness and dense laminate structure, G10 prevents delamination and cracking under heavy-load and high-vibration conditions. It is well-suited for high-demand applications such as military-grade hardware, aerospace assemblies, marine-grade systems, precision instruments etc.

RDS Composite has been supplying high-performance epoxy fiberglass sheets to the global market. We exercise strict oversight from raw material procurement through the entire production process to ensure our products meet international standards. We are committed to delivering reliably quality products and punctual, dependable service to our customers.