G10 is an epoxy-filled glass fiber, known for its excellent electrical insulating characteristic
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.

Properties

One of a class of phenolic laminate materials, G10 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.

Getting wet

Being lightweight and water-resistant, G10 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 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 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 to fashion
fins for large hobbyist rockets that fly at speeds of Mach 1.5 and beyond.

G10 Machining

G104 Machining does present challenges. The dust is an irritant and should be avoided. The cutting
tool must be kept cool because G10 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.

Requires experience

G10 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 materia
l to work with though and many regular machine shops avoid it.