G10/FR4 (Mil-I-24768/27) is an epoxy-filled glass fiber, known for its excellent electrical insulating characteristics making it ideal for printed circuit boards, insulating washers and transformer components. What’s less well known is that its properties make it ideal in many other applications.
One of a class of phenolic laminate materials, G10-FR4 is made by subjecting layers of epoxy-impregnated glass cloth to heat and pressure. (FR4 refers to the fire retardant version, made by adding bromine to the epoxy.) The resulting sheet or tube material has tensile strength comparable to aluminum and density nearly as low as carbon fiber. (Note though that G10/FR4 is anisotropic, meaning strength varies depending on the direction it’s measured in.) Other noteworthy properties are: low thermal conductivity, a high Tg (so it’s stable at elevated temperatures, unlike most plastics,) and it will not absorb water.
Being lightweight and water-resistant, G10/FR4 is ideal for a range of underwater applications. Remotely operated vehicles (ROV’s) are one. Used in aquaculture, the subsea oil and gas, commercial salvage, and for underwater surveying, ROVs can employ G10/FR4 in structural components and for enclosures and circuit boards. A second underwater application is in pipe saddles (the clamps holding pipes in place,) where water resistance coupled with strength and insulating characteristics are valuable attributes.
A few Surprises
Beyond industrial uses, G10/FR4 has found its way into at least three unexpected places. Anglers at a popular forum for spear fishermen find it ideal for the construction of spear guns. It’s lighter than aluminum and has comparable tensile strength. In much the same vein, its strength makes it a good candidate for fashioning knife handles and blades. Model rocket builders use G10/FR4 to fashion fins for large hobbyist rockets that fly at speeds of Mach 1.5 and beyond.
G10-FR4 Machining does present challenges. The dust is an irritant and should be avoided. The cutting tool must be kept cool because G10/FR4 softens and becomes gummy at temperatures above its Tg (around 285°F.) It’s also very abrasive and wears tools quickly, as anyone who’s ever machined PCB’s will know.
G10/FR4 applications go beyond circuit boards. High strength, low weight, expansion and conductivity plus low water absorption make it valuable in high humidity applications. It’s not the easiest material to work with though and many regular machine shops avoid it. Machining G10/FR4 is a specialized area and one where JMJ Profile excels.
Read more about G10-FR4 Material
Read more about Aerospace and Aviation use of G10 FR4
Also see: Mil-I-24768/27
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