PCB boards in Flexible PCB supplier china that use two layers of woven glass fabric and paper (cellulose) along with epoxy as the substrate material are called CEM-1 PCB boards. This material is milky white or milky yellow in colour with a smooth finish and used for single layer PCB fabrication only since it’s not compatible with plated through hole (PTH) technology.

CEM-1 provides excellent electrical and mechanical properties and is compatible with the lead-free reflow technology since it has a higher transition temperature than FR-4. It also has a superior flexural strength i.e. the ability of the dielectric to handle physical stress without breaking. CEM-1 is non-toxic and halogen-free and doesn’t contain phosphorus and antimony. It also holds good dimension stability as well.

The main disadvantages of the CEM-1 substrate when compared to FR4 are its mechanical characteristics which result in very fragile boards.