What is CEM-1 Material in PCB Board

Within the vast realm of printed circuit boards, various types of substrate such as aluminum, ceramics, FR4, and composite epoxy resins play a role in constructing the PCB’s core, serving as the foundation for supporting and interconnecting circuits. When engineers face different projects, they often choose PCB substrate that match the project’s characteristics. In this article, TechSparks will delve into an ancient substrate material – CEM-1 – and explore its advantageous features.

Table of Contents

What is CEM-1 Material and Why Use It


CEM-1 is a type of fiber-based composite material recognized by NEMA standards, reinforced with a layer of glass fiber laminate. Its primary composition includes paper substrate, epoxy resin, and various additives, which give the board a milky-white appearance. The full name of CEM-1 is Cotton-Epoxy-Methyl Ester-1, with the “1” indicating the grade or type of laminate, suggesting it falls within a lower classification in terms of general performance and characteristics. In the modern electronic world, as circuit complexity increases, the demand for multi-layer boards rises, directly promoting the development of FR4 materials, leaving CEM-1 in the background. However, even so, it still finds its place in specific applications. The following content outlines its characteristics:

  • Incompatible with plated through hole and can only be used for constructing single-layer circuit structures;
  • Priced at around 70% to 80% of similar products, considered a cost-effective alternative to FR4;
  • Capable of maintaining stable electrical performance within a temperature range of 100°C to 130°C;
  • CEM-1 PCB possesses a robust physical structure capable of supporting large components.

CEM-1 vs. CEM-3 vs. FR-4

MaterialCellulose substrates, epoxy and methyl ester resinsSame as CEM-1 but different material ratioFiberglass Cloth and Epoxy
AppearanceNot the smoothest but its surface is relatively flatMilky white appearance and smooth textureAppearance green, smooth surface without obvious fiber texture
 Available LayerSingle LayerSingle and Double Layer All structure types
Mechanical StrengthRelatively brittle, with lower mechanical strengthSuperior to CEM-1, influenced by material ratios Substrates with higher mechanical strength can accommodate impact resistance, bending resistance, and crack resistance
Electrical PropertiesDue to higher dielectric constant and dielectric loss, electrical performance is often poorerSimilar to CEM-1, there might be signal loss in high-frequency applicationsTypically exhibits good electrical performance, particularly in the low-frequency and mid-frequency ranges
MachinabilityProne to cutting or fracturing during the manufacturing processDespite improved mechanical properties, some issues persistCompatible with various intricate processes such as fine circuitry, small vias, and narrow traces
Flame RetardantLevel of flame retardancy varies based on the manufacturer and product specificationsSimilar to CEM-1, it falls slightly short of FR-4FR stands for Flame Retardant, with 4 indicating the grade, and it can self-extinguish in flame tests
CostCheapestModerateMost Cost Effective
ApplicationApplications with simple circuits and low performance requirements such as calculators, remote controls, digital clocks, etcCan be used in applications requiring heat resistance and mechanical strength such as industrial control equipment, automation equipment, etcMost commonly used substrate materials can be used whether it is high-performance servers, communication base stations or aerospace equipment
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