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 INDUSTRIAL LAMINATES Industrial laminates generally refers to a class of electrical insulating materials produced by impregnating fibrous webs of material with thermosetting resins, then fusing multiple layers together under high temperature and pressure. The result is an infusible laminate structure having a versatile combination of electrical, mechanical and chemical properties. Grade X. Hard, strong, paper-reinforced laminates; good tensile compression and flexural strengths; widely used for mechanical applications when electrical requirements are not severe; should be used with discretion under high humidity conditions. Grade XX. Hard paper-reinforced laminate with phenolic resin binder; good mechanical properties, high dielectric strength and resistance to moisture suit it for many usual electrical applications; good machinability. Grade XXX. Paper-reinforced laminate with a phenolic resin binder; has approximately the same mechanical properties as Grade XX but is considerably better electrically due to its high resin content; desirable for use at radio frequencies and under high humidity conditions (e.g., in telephone jacks where dimensional stability is important); minimum cold flow. Grade XP. Paper-reinforced laminate with phenolic resin binder and addition of a plasticizer; similar to Grade X but more flexible and slightly better electrically (not as strong mechanically); may be punched readily at room temperature in thicknesses up to 1/16-in; hot-punched up to 3/32 in. Grade XPC. Paper-reinforced laminate with plasticized phenolic resin binder; primarily intended for cold punching and shearing; more flexible than Grade XP. Grade XXP. Paper-reinforced laminate with plasticized phenolic resin binder; similar to Grade XX in electrical and moisture-resistant properties and to Grade XP in punchability; for electrical or electronic parts, especially those punched. Grade XXXP. Paper-reinforced laminate similar to Grade XXX, but bonded with plasticized resin; low in dielectric losses; low cold flow; recommended for punching of parts requiring high insulation resistance at high frequencies and high humidity; should be punched hot. Grade XXXP-C, FR-2. Paper-reinforced laminates similar to XXXP in mechanical properties, dielectric strength, dissipation factor and dielectric constant, but with better resistance to moisture and high insulation resistance; indicated for high humidity conditions; XXXP-C is recommended for punching and shearing at room temperature; FR-2 is a flame-retarded grade. Grade C. Fabric-reinforced laminate produced from cotton fabric weighing over 4 oz./sq.yd; thread count not more than 72/in. in filler direction, not over 140 total in warp and filler directions; Grade C is tough and strong, has high impact strength, machines readily and is good for a wide variety of mechanical applications such as gears, pulleys, and sheaves. Grade CE. Similar to Grade C in weight of fabric and thread count; greater resistance to moisture than grade C and controlled electrical properties; easy to machine; used in electrical applications requiring mechanical strength. Grade L. Fine-weave cotton fabric-reinforced grade with
phenolic binder, made from fabric weighing not over 4 oz./sq. yd.;
minimum thread count/in. in any ply is 72 in filler direction and
140 total in both warp and filler directions; has good mechanical
properties; machines easily and cleanly; recommended for fine punching
or threading; suited for close-tolerance machining; fine pitch gears
are typical uses. Grade FR-3. Paper-reinforced laminate bonded with epoxy resin; superior in electrical characteristics to Grade XXXP; good mechanical properties; suitable for punching at room temperature; FR-3 is flame retardant recommended for printed circuit boards and electrical insulation requiring low loss. Grade N-1. Staple fiber-nylon grade impregnated with phenolic resin; electrical properties of Grade XXXP and mechanical toughness of Grade C; improved insulation resistance for high humidity applications; high-voltage electrical insulators where low dielectric loss, high insulation resistance plus fungus resistance are required. Grade G-3. Continuous-filament woven glass-fabric grade with a phenolic resin binder; good thermal endurance; good mechanical strength, especially flexural, compressive, shear, and impact; very low dissipation factor. Grade G-5. Continuous-filament woven glass-fabric grade impregnated with melamine resin; high mechanical strength and arc resistance; excellent electrical properties under dry conditions; flame retardant. Grade G-7. Continuous-filament glass-cloth reinforcement with a silicone resin binder; good dielectric loss factor and insulation resistance under humid conditions over a wide temperature range; good heat and arc resistance. Grade G-9. Continuous-filament woven glass-fabric grade impregnated with melamine resin; high mechanical strength and arc resistance; good electric strength properties under wet conditions; flame retardant. Grade G-10, G-11, FR-4, FR-5. Continuous-filament woven glass-fabric grades impregnated with epoxy resin; particularly noted for good electrical values; possess low moisture absorption and low dissipation factor, and maintains electrical characteristics over a wide range of humidities and temperatures; G-10 and FR-4 retain 20% of their flexural strength at 150°C when tested at this temperature; G-11 and FR-5 retain 50% of their flexural strength when tested at the same temperature; FR-4 and FR-5 are flame retardant. Vulcanized fibre; commercial, bone, and insulation grades. Somewhat similar to Grade C laminate but with much higher moisture pickup; tough and resilient, with high resistance to arc, impact, abrasion and wear; used as washers, terminal block covers, insulating plates and switch covers, slot insulation, arc barriers, abrasive disks, railroad track insulation, trunks and materials-handling cases. Polyester/glass-mat sheet laminates. Polyester glass-mat
sheets are made from a mat of random-laid glass fibres which are
saturated with a polyester resin combined with suitable fillers
and cured under heat and pressure. Three typical grades are:
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