G10/FR4 Copper Clad Glass Epoxy Sheet

Copper-clad FR-4 is the standard flame-retardant glass-epoxy laminate with copper foil bonded to one or both faces, supplied for etching. The base laminate meets NEMA FR-4 and MIL-I-24768/27 Type GEE-F, with the cladding designated per IPC-4101: lengthwise flexural strength 65,000 to 80,000 psi, a 130 to 140C temperature index, volume resistivity around 3 x 10^15 ohm-cm and a dielectric constant of 4.4 to 5.0 at 1 MHz. Foil is normally electrodeposited; tell us if your process needs rolled-annealed and we will confirm what the lot carries.

Copper weight is a weight per unit area, not a thickness - one ounce means one ounce of copper spread over a square foot, which works out to about 1.4 mil or 35 microns. Half an ounce is about 0.7 mil or 17.5 microns, and two ounces about 2.8 mil or 70 microns.

Worth knowing: whether a quoted laminate thickness includes the cladding is genuinely not settled. IPC-4101D clause 1.1.2 permits nominal laminate thickness to be specified or measured either over the cladding or over the dielectric, and the standard resolves which applies by designation class. The thickness on these listings is the base laminate; add roughly 0.0014 inch per clad face at one ounce if you need the overall figure, and tell us if your drawing is dimensioned over the copper.

It is used for printed circuit board fabrication and prototyping, RF and microwave circuit laminates, and etched groundplanes.

Machining and handling. The glass abrades tooling, so carbide is the floor and diamond-coated or PCD cutters are what hold tolerance in production; run high spindle speeds with secure workholding and design in generous internal radii, because small tools wear out fast against glass. Threaded holes are normally milled rather than tapped and external threads turned or thread-milled, since the plies can delaminate. The laminate has no hazards as shipped, but cutting it releases a fine dust, and the epoxy resin in that dust is classified as a skin and respiratory sensitiser - use local exhaust, a dust respirator, eye protection and gloves, and work to your own site's exposure limit, because published limits for glass dust differ by jurisdiction and by whether total or respirable dust is measured. It comes off as powder rather than chips, so vacuum it up rather than blowing it airborne. These are our shop notes, not a manufacturer specification.