A laminate in printed circuit board, also called copper clad laminate, or PCB core, is a main PCB base material for circuit board manufacturing. Laminates are manufactured by curing under pressure and temperature layers of cloth or paper with thermoset resin to form an integral final piece of uniform thickness.
The cloth or fiberglass material used, resin material, and the cloth to resin ratio determine the laminate’s type designation and therefore the characteristics of the laminate produced. Dielectrics in laminates are:
- RF-35: fiberglass-reinforced ceramics-filled PTFE. Relatively less expensive, good mechanical properties, good high-frequency properties.
- PTFE (Teflon): expensive, low dielectric loss, for high frequency applications, very low moisture absorption (0.01%), mechanically soft. Difficult to laminate, rarely used in multilayer applications.
- Alumina: a ceramic. Hard, brittle, very expensive, very high performance, good thermal conductivity.
- Polyimide: a high-temperature polymer. Expensive, high-performance. Higher water absorption (0.4%). Can be used from cryogenic temperatures to over 260 °C.
- FR-6: matte glass and polyester
- FR-5: woven glass and epoxy, high strength at higher temperatures, typically specified to 170 °C.
- FR-4: woven glass and epoxy
- FR-3: cotton paper impregnated with epoxy, typically rated to 105 °C.
- FR-2: phenolic cotton paper, typically specified to 105 °C, some grades rated to 130 °C.
- FR-1: like FR-2, similar to cardboard. Room-temperature punchable. Poor moisture resistance. Low arc resistance.
- G-11: wove glass and epoxy, high resistance to solvents, high flexural strength retention at high temperatures. Typically rated to 170 °C.
- G-10: woven glass and epoxy, high insulation resistance, low moisture absorption, very high bond strength. Typically rated to 130 °C.
- CEM-5: woven glass and polyester
- CEM-4: woven glass and epoxy
- CEM-3: non-woven glass and epoxy
- CEM-2: cotton paper and epoxy
- CEM-1: cotton paper and epoxy