Bakelite Sheet Standards & Types

Comprehensive guide to Bakelite sheets. Learn about key standards (NEMA XX/XXX, C/CE, IEC), material types, physical properties, and application scenarios to choose the right in...

Standards and Types of Bakelite Sheets

Bakelite sheets (also known as phenolic paper laminated sheets) are hard insulating materials made from paper, cotton cloth, or other reinforcement materials impregnated with phenolic resin and hot-pressed under high temperature and pressure. Featuring high mechanical strength, excellent electrical insulation, heat resistance, and corrosion resistance, they are widely used in electronics, electrical appliances, mechanical processing, mold manufacturing, and other fields.

bakelite sheet (phenolic paper sheet)

Below is a detailed introduction to the industry standards and common types of Bakelite sheets:

1. Executive Standards for Bakelite Sheets

The production and quality evaluation of Bakelite sheets primarily follow relevant domestic and international standards:

Chinese National Standards (GB/T)

GB/T 1303 Series: China’s national standard for industrial rigid laminated sheets based on thermosetting resins for electrical purposes. It specifies the mechanical and electrical performance requirements for various phenolic paper and cotton laminates.

International Electrotechnical Commission Standards (IEC)

IEC 60893: Industrial rigid laminated sheets based on thermosetting resins for electrical purposes (e.g., IEC 60893-3-2 specifies requirements for phenolic resin laminates).

National Electrical Manufacturers Association Standards (NEMA)

NEMA LI 1: A widely used international standard for industrial laminated thermosetting products, commonly used to classify Bakelite sheets of different performance grades (such as X, XX, XXX, C, CE, etc.).

2. Main Types of Bakelite Sheets

Based on the reinforcing substrate and functional characteristics, Bakelite sheets are mainly categorized as follows:

Paper-Based Bakelite Sheets (Most Common)

Representative Grade: Chinese National Standard 3021 (International equivalent: IEC PFCP201 / US NEMA XX or XXX).
Material & Features: Made by impregnating insulating paper (such as wood pulp paper or kraft paper) with phenolic resin under high pressure. They offer lower cost, good machinability, relatively low water absorption, and good electrical properties and mechanical strength under ambient conditions.
Applications: Suitable for insulating structural components in motors and electrical equipment with general mechanical requirements, as well as fixtures and backing plates.

Cold-Punching Sheets (Special Process Type)

Representative Grade: XPC grade or modified cold-punching phenolic sheets.
Material & Features: Made of modified phenolic resin combined with a paper base. The main feature is the ability to undergo punching processing at room temperature (cold punching), eliminating the cumbersome heating process required for traditional sheets.
Applications: Commonly used for electronic components, gaskets, dedicated PCB backing boards, and various stamped metal insulation parts.

Anti-Static Bakelite Sheets

Features: Formulated with anti-static agents or specialized active powders during manufacturing, controlling surface and volume resistivity within a specific range (typically $10^6 – 10^9$ ohms) to effectively prevent static charge accumulation.
Applications: Test fixtures for static-sensitive electronic instruments, PCB test frames, SMT processing jigs, etc.

3. Common Specifications and Physical Properties

Colors: Most commonly orange-red, dark brown (coffee brown), and black.
Common Thickness: Ranging from 0.5 mm to 50 mm (thicker specifications can be customized upon request).
Standard Dimensions: Common sheet sizes include 1000mm × 2000mm, 1020mm × 1220mm, 1020mm × 1020mm, etc.
Thermal Class: Usually Class E , with a long-term operating temperature of 120°C.