NEMA grades G10 and FR4 Glass Cloth Reinforced Epoxy - natural color is typically yellowish to light green. The most versatile all-around laminate grades are continuous glass woven fabric impregnated with an epoxy resin binder. (Epoxy resins are among the most versatile and widely used plastics in the electronics field, primarily because water absorption is virtually nil, rendering it an outstanding insulator. Beyond its electrical insulating properties, epoxy resins exhibit superior adhesive properties and great dimensional stability - shrinkage is usually less than 1 percent). G10 andFR4 have extremely high mechanical strength, good dielectric loss properties, both wet and dry. The main difference between NEMA Grades G10 and FR4 is that FR4 is a fire retardant grade of G10. Therefore, FR4 may be substituted where G10 is called out except in applications where halogens are not desired. G10 can never be substituted where FR4 is called for. (G10 certifies to Mil-I-24768/2 GEE; FR4 certifies to Mil-I-24768/27 GEE-F.)
NEMA grades G11 and FR5 Glass Cloth Reinforced Epoxy - natural color is typically yellow green to amber. This grade is similar to G10 & FR4 with the addition of a higher operating temperature and some improved mechanical strength at elevated temperatures. The main difference between NEMA Grades G11 and FR5 is that FR5 is a fire retardant grade of G11. Therefore, FR5 may be substituted where G11 is called out except in applications where halogens are not desired. G11 can never be substituted where FR5 is called for. (G11 certifies to Mil-I-24768/3 GEB; FR4 certifies to Mil-I-24768/28 GEB-F.)
NEMA grades G5 and G9 Glass-Cloth Reinforced Melamine - natural color is typically grayish brown. These grades are composed of a continuous glass woven cloth base impregnated with melamine resin binder. (Melamine resins, once cured, are the hardest, most rigid and abrasion resistant of the standard resins employed in the production of industrial laminates. However, prolonged exposure to high temperature can adversely affect its mechanical and electrical strength properties. Arc resistance, however, may remain unaffected despite excessive thermal exposure). Melamines are the hardest of laminates, exhibiting good dimensional stability and arc resistance. A key difference between NEMA Grades G5 and G9 are that G9 is more resistant to the elements of the environment. Thus, G9 may be safely substituted where G5 is called for. (G5 certifies to Mil-I-24768/8 GMG; G9 certifies to Mil-I-24768/1 GME.)
NEMA grades G7 Glass-Cloth Reinforced Silicone - natural color is typically cream to white. Composed of a continous glass woven cloth base impregnated with a silicone resin binder, this grade has excellent heat and arc resistance. (Silicone thermosetting resins are among the best of all polymer materials in resistance to temperature. Hence, silicone is broadly used for high temperature electronic applications requiring low electrical losses. Silicone isn't as strong as epoxies and phenolics upon aging at lower temperatures but is stronger upon aging over 400F). G7 has extremely good dielectric loss properties under dry conditions and good electrical properties under humid conditions, although the percentage of change is high. (G7 certifies to Mil-I-24768/17 GSG.)
NEMA grades GPO-1 (tan color), GPO-2 (red color), GPO-3 (red color) Glass-Mat Reinforced Polyester - These grades are composted of random mat (non-woven) fiberglass reinforcement held together by a polyester resin binder. (Polyesters are versatile resins which handle much like epoxies. Of course, the basic resins are chemically different. It's their physical application forms which make them similar. Despite lower costs, the important disadvantages of polyesters as compared with epoxies, is lower adhesion to most substrates, higher polymerization shrinkage, a greater tendency to crack during cure or in thermal shock and greater change of electrical properties in a humid environment). GPO-2 offers superior arc resistance over GPO-1 while GPO-3 offers both arc and track resistance. (GPO-1 certifies to Mil-I-24768/4 GPO1; GPO-2 certifies to Mil-I-24768/5 GPO2 and GPO-3 certifies to Mil-I-24768/6 GPO3.)
NEMA grades X, XX, XXX Paper Reinforced Phenolic - natural color is typically light tan to brown. These grades are composed of a paper base impregnated with phenolic resin binder. (Phenolics are the oldest, best-known general purpose themoset resins. They are among the lowest in cost and easiest to process. Phenolics are quite adequate for a fair percentage of electrical applications. Generally speaking, they are not equivalent to epoxies in resistance to moisture, humidity, dimensional stability, shrinkage and retention of electrical properties in extreme environments). The paper reinforced phenolic has good electric strength properties with fair mechanical strength and are outstanding for use as template material and/or back-up material. A good rule of thumb in selecting a paper grade is to remember the more X's the better the electrical properties, while the fewer X's represent superior mechanical properties. Paper grades can be modified by adding plasticizers to make them more conducive to part punching resulting in a P suffix added to the X designation, i.e., XP, XXP, XXXP. (Grade X certifies to Mil-I-24768/12 PBM; grade XX certifies to Mil-I-24768/11 PBG and grade XXX certifies to Mil-I-24768/10 PBE.)
NEMA grades C and CE Canvas Cotton-Cloth Reinforced Phenolic - natural color is typically light tan to brown. C and CE grades are composed of a continuous cotton woven cloth impregnated with a phenolic resin binder. ( Phenolics are the oldest, best-known general purpose themoset resins. They are among the lowest in cost and easiest to process. Canvas Phenolics may be adequate for a fair percentage of electrical applications, but are not generally recommended for primary electrical insulation. Generally speaking, they are not equivalent to epoxies in resistance to moisture, humidity, dimensional stability, shrinkage, and retention of electrical properties in extreme environments). These grades contain a medium weave canvas and are known primarily for their mechanical properties. (Grade C certifies to Mil-I-24768/16 FBM; grade CE certifies to Mil-I-24768/14 FBG.)
NEMA grades L and LE Linen Cotton-Cloth Reinforced Phenolic - natural color is typically light tan to brown. This grade is composed of a continuous cotton woven cloth impregnated with phenolic resin binder. This grade contains fine woven linen and, like the canvas phenolic; is known for its mechanical properties. The finer weave allows for machining more intricate details than canvas grade, such as gear teeth, etc. These grades are not recommended for primary electrical insulation, but grade LE exhibits superior moisture resistance to grades L, C and CE, and thus is an adequate insulator for a fair number of applications. (Grade L certifies to Mil-I-24768/15 FBI; grade LE certifies to Mil-I-24768/13 FBE.)