Phenolic Laminate Board, often referred to as Bakelite Sheet or Phenolic Sheet, is a composite material made by laminating layers of paper, cotton fabric, or glass fabric impregnated with a thermosetting phenolic resin under high temperature and pressure. Since its invention in the early 20th century, it has become a cornerstone material in industries such as electronics, electrical engineering, machinery, and transportation due to its excellent mechanical strength, superior electrical insulation properties, and outstanding cost-effectiveness.
What is Phenolic Laminate Board?
Phenolic Laminate Board is a thermoset plastic. This means that once it is cured under heat and pressure, its molecular structure forms an irreversible three-dimensional network, giving it exceptional dimensional stability, heat resistance, and creep resistance. Unlike thermoplastics, it cannot be remoulded by reheating.
Its manufacturing process results in the material being anisotropic—its properties differ along the laminate direction compared to the perpendicular direction, a characteristic that must be considered during design and machining.
Core Properties and Advantages of Phenolic Laminates
The wide applicability of phenolic laminate stems from its unique combination of properties:
Excellent Electrical Insulation: This is why it was originally called "Bakelite Sheet." It has high surface and volume resistivity, effectively preventing current leakage, making it ideal for circuit breakers, distribution panels, and transformer insulation parts.
High Mechanical Strength and Rigidity: The laminated structure gives the material outstanding impact, flexural, and compressive strength, allowing it to withstand significant mechanical loads and ensuring the structural integrity of components over long-term use.
Superior Flame Retardancy (UL94 V-0): Phenolic resin is inherently flame retardant, often achieving a UL94 V-0 rating (the highest flame retardancy class) without additives, making it extremely safe in applications involving arc or high-temperature risks.
Good Heat Resistance and Dimensional Stability: Under continuous high-temperature conditions (typically up to 120°C to 150°C, depending on the grade), phenolic sheets can maintain their shape and properties without softening or deforming.
Excellent Machinability: Phenolic laminate board is easy to process using CNC machining, drilling, turning, and milling, allowing for cost-effective production of precision parts in complex shapes.
High Cost-Effectiveness: Compared to other high-performance engineering plastics (like PEEK or PI), phenolic board offers an exceptional price-to-performance ratio, especially suitable for high-volume production applications.