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A Comparison of FR4, G10, and G11: Similarities and Differences!


FR4, G10, and G11 are commonly used materials in various industries due to their desirable properties. While they share certain similarities, there are also notable differences between them. In this article, we will explore their physical properties to understand how FR4, G10, and G11 differ from each other.


Specific Gravity:
FR4 and G11 both have a specific gravity of approximately 1.85. This indicates their similar density, which can be beneficial for applications where weight is a consideration.

Rockwell Hardness:
With a Rockwell Hardness of 115 on the M-Scale, both FR4 and G10 possess similar hardness. This property ensures good resistance to scratches and wear, contributing to their durability.

Moisture Absorption:
FR4 and G10 exhibit a moisture absorption rate of 0.15%, indicating their low water absorption. This property is advantageous in applications where moisture resistance is crucial to maintaining material integrity.


Material Designation and Specifications:
FR4 is designated under MIL-I-24768/27, G10 under MIL-I-24768/2, and G11 under MIL-I-24768/3. These military specifications define the material compositions, manufacturing processes, and performance characteristics specific to each grade.

Flexural Strength and Modulus:
FR4 demonstrates a flexural strength of 65,000 psi (lengthwise) and 55,000 psi (crosswise), while G10 exhibits slightly higher flexural strength at 70,000 psi (lengthwise) and 60,000 psi (crosswise). G11 surpasses both with a flexural strength of 75,000 psi (lengthwise) and 65,000 psi (crosswise). This indicates that G11 offers the highest resistance to bending forces among the three materials.

Tensile Strength:
FR4 has a tensile strength of 50,000 psi (lengthwise) and 40,000 psi (crosswise), while G10 and G11 exhibit comparable tensile strength at 50,000 psi (lengthwise) and 36,000 psi (crosswise) for G10 and 43,000 psi (crosswise) for G11. This property highlights the materials’ resistance to stretching forces.

Izod Impact Strength:
FR4 demonstrates higher Izod impact strength compared to G10 and G11. While FR4 achieves 14 ft/lb/in (lengthwise) and 12 ft/lb/in (crosswise), G10 offers 8.00 ft/lb/in (lengthwise) and 6.00 ft/lb/in (crosswise), and G11 has an impact strength of 7 ft/lb/in (lengthwise) and 5.5 ft/lb/in (crosswise). This property reflects the materials’ ability to withstand impact or sudden forces.

Compressive Strength:
G11 exhibits the highest compressive strength among the three materials, with a value of 70,000 psi. FR4 follows with a compressive strength of 60,000 psi, while G10 has a slightly higher compressive strength of 66,000 psi.

FR4 is classified as flame retardant according to the UL-94 V0 standard, whereas G10 and G11 are rated non-flame retardant at the HB grade.

In summary, FR4, G10, and G11 are similar in terms of specific gravity, Rockwell hardness, and moisture absorption. However, they differ in material designations, flexural strength and modulus, tensile strength, Izod impact strength, and compressive strength.

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