The Basics of Industrial Laminates
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The Basics of Industrial Laminates

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http://www.acculam.com | Thermoset laminates are often referred to as “phenolics” and older trade names such as Bakelite, Textolite, Micarta, Phenolite, etc. You can get them in many grades and ...

http://www.acculam.com | Thermoset laminates are often referred to as “phenolics” and older trade names such as Bakelite, Textolite, Micarta, Phenolite, etc. You can get them in many grades and in sheet, tube, rod and molded forms. Industrial Laminate grades are differentiated by a variety of resin matrix binders that are reinforced by various fiber materials.

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The Basics of Industrial Laminates The Basics of Industrial Laminates Document Transcript

  • Industrial Laminates “The Basics” prepared by Michael Stacey • Accurate Plastics, Inc. • Yonkers, New York In a comprehensive way, I have attempted to cover the basics of industrial laminates. Thermoset plastic industrial laminates date back over 90 years, and much like aspirin, industrial laminate is an old friend that continues to present new remedies for today and tomorrow's toughest engineering headaches. Be sure to prescribe industrial laminates to your customers...then call me in the morning. (wink!) In 1906, Dr. Leo Bakeland experimented with the polymerization of phenolic resins. He found that by adding formaldehyde and heat, a chemical cross linkage took place; thermoset plastics were born. Soon after, it was discovered that cotton cloth and paper materials could be impregnated with this same mixture, semicured and then made into a stack of sheets or wrapped around a mandrel and subsequently put into a hydraulic press where heat and pressure could be applied. Full polymerization took place rendering hard, dense, reinforced thermoset plastics which today are known as industrial laminates. Simply put, thermoset plastics can be compared to cement, once cured they’re set, hence the name thermoset. Thermoplastics can be compared more to wax in-as-much as they can be remelted and reshaped upon the reapplication of heat. However, one key resulting difference is that thermoplastics lack the rigidity of thermoset laminates, as the tensile modulus of the following materials indicate: Graphite Epoxy Steel Aluminum Glass Epoxy Polycarbonate (thermoset plastic) (metal) (metal) (thermoset plastic) (thermoplastic) 40,000,000 psi 30,000,000 psi 10,000,000 psi 5,800,000 psi 450,000 psi Thermoset Plastic Industrial Laminates Thermoset plastic industrial laminates are uniformly dense and structurally strong materials that will not soften appreciably under the reapplication of heat. They are extremely durable plastics that are lightweight and moisture resistant. They are thermoset plastic resin impregnated reinforcing substrate materials that are cured under heat and pressure to form solid shapes having high mechanical and insulating properties. Industrial laminates are available in sheet, rod, tube and angle. Since these laminates are comprised of a combination of materials, they are also referred to as composites. Thermoset plastic industrial laminates typically have a layered construction with no fewer than two components: The first is a reinforcing substrate such as woven glass cloth, random glass mat, glass filaments, woven canvas cotton fabric, woven linen cotton fabric, paper, woven aramid fabric, random mat aramid, woven graphite fabric, random mat graphite and others. The second is a thermoset plastic resin binder that serves to adhere Thermoset Laminate Layered Construction T TECHNICAL REFERENCE BL6 INDUSTRIAL LAMINATES • Epoxy Grades Melamine Grades Silicone Grades Polyester Grades Phenolic Paper Grades Phenolic Cotton Grades • Thermoset Industrial Laminate Properties • Manufacturing Process • Applications resin binder reinforcing substrate You Know� � It’s Right...� When It’s� � Accurate P L A S T I C S , the layers of reinforcing substrates to each other to form a solid unit. Resin binders include epoxies, melamines, phenolics, polyesters, silicones and others. Unlike other groups of plastic materials, thermoset plastic industrial laminates have their own standards which are published by NEMA (National Electrical Manufacturers Association). In concert with member manufacturers, NEMA standards are set and “mininum values” published. The most commonly used NEMA thermoset laminate grades are as follows: I N C. Headquarters, Mfg. 18 Morris Place, Yonkers, NY 10705 Phone: 914-476-0700 Fax: 914 / 476-0533 www.acculam.com
  • Epoxy Grades NEMA grades G10 and FR4 GlassCloth Reinforced Epoxy — natural color is typically a yellowish to light green. The most versatile allaround 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/FR4 has extremely high mechanical strength, good dielectric loss properties, and good electric strength 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 can be safely substituted where G10 is called out, while 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 GlassCloth 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 can be safely substituted where G11 is called out, while G11 can never be substituted where FR5 is called for. (G11 certifies to Mil-I24768/3 GEB; FR5 certifies to Mil-I-24768/28 GEB-F.) Melamine Grades NEMA grades G5 and G9 Glass-Cloth Reinforced Melamine — natural color is typically a grayish brown. These grades are composed of a continuous glass woven cloth base impregnated with a 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. It’s also caustic resistant. A key difference between NEMA Grades G5 and G9 are that G9 is more resistant to the elements of the environment. Thus, G9 can be safely substituted where G5 is called for. (G5 certifies to Mil-I-24768/8 GMG; G9 certifies to Mil-I-24768/1 GME.) Polyester Grades NEMA grade GPO-1 (tan color), GPO-2 (red color) and GPO-3 (red color) GlassMat Reinforced Polyester — These grades are composed 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). Phenolic Paper Grades Accurate Plastics manufactures Acculam™ industrial thermoset laminate sheet, rod, tube, angle and channel. Silicone Grade NEMA grades G7 Glass-Cloth Reinforced Silicone — natural color is typically cream to white. Composed of a continuous 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 400°F). 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-I24768/17 GSG.) NEMA grades X, XX and XXX Paper Reinforced Phenolic — natural color is typically light tan to brown. These grades are composed of a paper base impregnated with a phenolic resin binder. (Phenolics are the oldest, bestknown general purpose thermoset 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 to Mil-I24768/11 PBG and grade XXX to Mil-I24768/10 PBE).
  • Phenolic Cotton Grades 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, bestknown general purpose thermoset resins. They are among the lowest in cost and easiest to process. Phenolics are quite adequate for a fair percentage of electrical applications. grade is composed of a continuous cotton woven cloth impregnated with a phenolic resin binder. This grade contains a fine weave 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). 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. These grades are not recommended for primary electrical insulation. (Grade C certifies to Mil-I-24768/16 FBM; grade CE certifies to Mil-I-24768/14 FBG). NEMA grades L and LE Linen CottonCloth Reinforced Phenolic — natural color is typically light tan to brown. This THERMOSET INDUSTRIAL LAMINATE PROPERTIES Minimum Values G10, FR4 G11, FR5 G5, G9 G7 GPO 1 GPO 3 X XX XXX C, CE L, LE glass cloth epoxy glass cloth epoxy HT glass cloth melamine glass cloth silicone glass mat polyester glass mat polyester paper phenolic paper phenolic paper phenolic canvas phenolic linen phenolic 40,000 35,000 40,000 35,000 37,000 30,000 23,000 18,000 12,000 –– 11,000 –– 20,000 16,000 16,000 13,000 15,000 12,000 9,500 7,500 12,500 8,750 flatwise, PSI edgewise, PSI 60,000 35,000 60,000 35,000 70,000 25,000 45,000 14,000 40,000 –– 30,000 –– 36,000 19,000 34,000 23,000 32,000 25,500 37,000 23,500 37,000 25,000 lengthwise, PSI crosswise, PSI 55,000 45,000 55,000 45,000 55,000 35,000 23,000 20,000 23,000 –– 20,000 –– 25,000 22,000 15,000 14,000 13,500 11,800 17,000 15,000 15,000 13,750 Modulus of Elasticity in flex x10 -3 lengthwise, PSI crosswise, PSI 2,700 2,200 2,700 2,200 2,500 2,000 1,400 1,200 –– –– –– –– 1,800 1,300 1,400 1,100 1,300 1,000 950 850 1,050 850 Shear Strength, PSI 19,000 19,000 20,000 17,000 –– –– 12,000 11,000 10,000 11,500 11,750 7 5.5 7 5.5 12 8 8.5 7.5 –– –– –– –– 4 0.5 1.3 0.35 1 0.35 3.2, 2.3 1.9, 1.4 2.5, 1.8 1.1, 1 NEMA grades reinforcements resin binders Properties Tensile Strength lengthwise, PSI crosswise, PSI Compressive Strength Flexural Strength IZOD Impact flatwise, ft-lb/in of notch edgewise, ft-lb/in of notch Rockwell Hardness M scale 110 110 120 100 –– –– 110 105 110 104 105 Specific Gravity 1.82 1.82 1.9 1.68 1.8 1.85 1.36 1.34 1.32 1.35 1.34 Coefficient of Thermal Expansion cm/cm-°C x 10 -5 .9 .9 1 1 –– –– 6 2 1.4 2 2 Water Absorption .062” thick, % per 24 hrs .125” thick, % per 24 hrs .500” thick, % per 24 hrs 0.25 0.15 0.10 0.25 0.15 0.10 0.8 0.7 0.4 0.3 0.2 0.15 0.35 –– –– 0.4 –– –– 6 3.3 1.1 2 1.3 0.55 1.4 0.95 0.45 4.4, 2.2 2.5, 1.6 1.2, 0.75 2.5, 1.95 1.6, 1.3 0.9, 0.7 Dielectric Strength,volt/mil perpendicular to laminations; short .062” thick .125” thick 500 400 500 400 400 350 400 350 370 –– 400 –– 700 500 700 500 650 470 200, 500 150, 360 200, 500 150, 360 Dissipation Factor condition A, 1 megacycle 0.025 0.025 0.017 0.003 –– –– 0.06 0.045 0.038 Dielectric Constant condition A, 1 megacycle 5.2 5.2 7.12 4.2 –– –– 6 5.5 5.3 Insulation Resistance Condition: 96 hours at 90% relative humidity (in megaohms) 200,000 200,000 10,000 200,000 –– –– –– –– –– –– –– 2,000 1,600 1,700 650 –– –– 700 800 950 1,800 1,600 Bond Strength, in lbs Max Operating Temperature approximate ° F continuous sheet mil spec: Mil-I-24768 / _ _, type 0.1, 0.055 0.1, 0.055 -, 5.8 -, 5.8 285 300 285 465 265 265 285 285 285 265 265 2, GEE 27, GEE-F 3, GEB 28, GEB-F 8, GMG 1, GME 17 GSG 4 GPO1 6 GPO3 12 PBM 11 PBG 10 PBE 16, FBM 14, FBG 15, FBI 13, FBE
  • MANUFACTURING FLOW CHART Press Shear Resin Sheet B Stage� Pallet Base� Mat’l Tube Dip Pan Oven Tube Roller Manufacturing Process Thermoset plastic industrial laminates are identified in process by three stages A, B and C stages: A-stage refers to the key raw materials described earlier – reinforcing substrates and resin binders. B-stage refers to the product produced when reinforcing substrates and resin binders are brought together but not cured. The reinforcing substrate is unwound from a large master roll and dipped into a bath of liquefied resin binder. The reinforcing substrate becomes either saturated, as is the case with absorbent papers and cotton cloths, or coated, as is the case with glass and graphite cloths. Once the wet resin binder is joined with the reinforcer substrate in this method, it is slowly drawn through a long conveyorized oven where the liquefied resin binder is dried. The result leaves dry semicured resin binder in and/or on the reinforcing substrate. Once joined and dried in this fashion, the product is referred to as B-stage or prepreg, and the process described is called B-staging, prepreging or treating. C-stage refers to sheet, rod, tube, angle or other in their “cured stage.” • Sheets — B-stage is sheeted into plys then laid on top of each other into predetermined stacks that will render a given thickness. These stacks are placed into the hydraulic laminating press between two flat surfaces and pressure is applied. While under pressure, heat is introduced to begin the bake cycle. The resin in the B-stage product is reactivated by the heat to a sticky state which moves slowly, filling and bonding the layers together until it eventually hardens and cures. Once plys bond to each other and cure they are referred to as C-stage laminate sheet and the process described is called laminating or pressing. • Rods — the B-stage is convolutely wrapped under tension onto itself, much like a roll of paper towels is wound. Once the Bstage is rolled to form a rod, it is placed into a laminating press which has upper and lower half round mold cavities. When the two half round molds close and meet each other a full round is formed. The size of the mold cavity determines the diameter of the finished rod. Once pressure is applied, the layers are pressed together filling all voids. Similar pressures and heat cycles employed for making sheet are used. When the layers bond to each other and cure, they are referred to as C-stage laminate rod or rolled and molded rod. • Tubes — rolling tubes are nearly identical to rolling rods with the exception that a steel rod called a mandrel is employed to size and form the inside diameter of the tube. Bstage rolled tubes are usually placed into an oven chamber as opposed to a press. Tube bake cycles compare to those of sheet and rod. Once cured, the center mandrel is extracted. The final cured product is referred to as Cstage laminate tube or rolled tube. • Angles — this process is nearly identical to that of sheets except the mold cavities are “V” shaped rather than flat surfaces. The final cured product is referred to as C-stage laminate angle or molded angle. • Other shapes — once cured, the end product is referred to as C-stage. APPLICATIONS FOR THERMOSET INDUSTRIAL LAMINATES Industrial laminates are used in the following industries: • Electronics • Electrical • Machinery • Automotive and Trucking • Metal Finishing • Aviation • Chemical • Home Appliance • Textile Of these, the largest markets are electrical and electronics, where thermoset industrial laminates provide strong reliable insulators for applications in : • Relays • Bus Bars • Standoffs • Washers • Arc Shields • Vanes • Test Board • Panels • Sockets • Coils • Fuses • Motors • Generators • Gaskets • Transformers • Circuit • Condensers Boards You Know� It’s Right...� When It’s�P L A � New York Accurate S T I C S , 18 Morris Place, Yonkers, NY 10705 Phone: 914-476-0700 • Fax 914-476-0533 TM • Switches • Terminal Strips These laminates, as a group, are the hidden work horses in many industrial applications. I N C. West Virginia PO Box 2287, Weirton, WV 26062 Phone: 914-476-0700 • Fax 304-723-1625 Massachusetts 33 Tech Park Drive, Falmouth, MA 02536 Phone: 914-476-0700 • Fax 508-457-9275