G-10/FR-4 (Glass Epoxy)
Glass-fabric reinforced epoxy — the highest-strength insulator we stock, and a laminate rather than a plastic. In sheet and rod.
G-10 typical properties
Figures are for G-10 glass-epoxy laminate, NEMA grade G-10 (Norplex-Micarta NP500A). These are typical values, not a specification. The datasheet behind each figure is linked in its row: the manufacturer’s where one publishes the figure, a distributor’s otherwise. Figures vary by supplier and test method, so confirm against the datasheet for the grade and stock form you are designing with.
| Property | Typical value |
|---|---|
| Density | 1.77g/cc |
| Tensile strength | 43,000psi ultimate, no yield pointASTM D638 (Condition A, lengthwise)Norplex-Micarta NP500A Technical Data Bulletin (NEMA G-10 glass-epoxy), 7/14/2022 (opens in a new tab) |
| Tensile modulus | Not published by the makers cited |
| Flexural modulus | 3,400,000psi ASTM D790 (Condition A, lengthwise)Norplex-Micarta NP500A Technical Data Bulletin (NEMA G-10 glass-epoxy), 7/14/2022 (opens in a new tab) |
| Hardness | 99Rockwell M ASTM D785 (0.250 in build-up)Norplex-Micarta NP500A Technical Data Bulletin (NEMA G-10 glass-epoxy), 7/14/2022 (opens in a new tab) |
| Izod impact, notched | 9.5ft-lb/in ASTM D256 (Condition E-48/50, lengthwise)Norplex-Micarta NP500A Technical Data Bulletin (NEMA G-10 glass-epoxy), 7/14/2022 (opens in a new tab) |
| Temperature index (UL 746B, electrical) | 266°F UL 746B temperature index, a recommendation onlyNorplex-Micarta NP500A Technical Data Bulletin (NEMA G-10 glass-epoxy), 7/14/2022 (opens in a new tab) Electrical temperature index. The mechanical index is 284 °F. |
| Heat deflection temp @ 264 psi | Not published by the makers cited |
| Water absorption, 24 h | 0.22% ASTM D570 (Condition D-24/23 = 24 h immersion at 23 °C)Norplex-Micarta NP500A Technical Data Bulletin (NEMA G-10 glass-epoxy), 7/14/2022 (opens in a new tab) |
| Thermal expansion (CTE) | 0.67×10⁻⁵ in/in/°F IPC-TM-650 2.4.24, in-plane (x-axis)Norplex-Micarta NP500A Technical Data Bulletin (NEMA G-10 glass-epoxy), 7/14/2022 (opens in a new tab) |
| FDA food contact | Not rated The cited suppliers make no food-contact statement for this grade. |
Figures are for G-10, lengthwise where the datasheet gives two directions; crosswise values are lower. FR-4 is the flame-retardant grade and its published values differ. A laminate has no yield point, so tensile strength is the ultimate value.
What G-10/FR-4 is
Glass fabric reinforced epoxy with superior electrical and mechanical properties.
G-10 or FR-4
They are the same glass-epoxy laminate with one difference that decides the specification: FR-4 is the flame-retardant grade, G-10 is not. If the part sits in an enclosure or an application with a flammability requirement, it is FR-4. Otherwise the two behave alike. Against the unreinforced plastics, glass epoxy is chosen when a part has to insulate and carry real load at the same time — it is far stiffer and stronger than any thermoplastic insulator, and unlike them it will not soften and flow as it warms.
Machining G-10/FR-4
This is the most abrasive material we machine. The glass reinforcement destroys tooling — carbide is the minimum and diamond-coated tooling earns its cost on production runs, and a tool that would run all day in acetal is finished in minutes. It cuts dry and produces a hard, fine dust rather than chips, so extraction is a requirement rather than good practice. Delamination and edge breakout at the laminate layers are the failure modes: back the material where the cutter exits, keep tooling sharp, and drill with the workpiece properly supported.
Need G-10/FR-4 parts machined to print?
Send us a drawing and we will quote it. Precision plastic machining in Linden, New Jersey since 1968.