... ),with good dielectric stability at high humidity, ROSH Fr-4 Epoxy Glass Cloth Laminated Sheet (FR4 sheet,FR4 insualtion parts)is ... of electrical non-alkali and non-wax cloth impregnated with epoxy resin by procesing under pressure and heat.It is insulation class ... appliancelines,PCB test,transformers,ect.Fr4 is flame retardant. FR4 Epoxy Glass Cloth Laminated Sheet,With ROSH Certification