FR4 material has excellent electrical insulation properties, mechanical strength, and heat resistance, and is one of the most commonly used substrates in the current PCB industry.
1. Copper Lamination: Copper foil and pre-impregnated epoxy resin fiberglass cloth are pressed together under high temperature and pressure to form a substrate.
2. Pattern Transfer: Circuit patterns are transferred onto the copper layer using photolithography.
3. Etching: Excess copper foil is removed using a chemical solution to form circuit traces (line width/spacing can be as small as 3/3 mil).
4. Lamination and Drilling: Multilayer boards need to be laminated and formed through-holes by mechanical drilling (minimum hole diameter can reach 0.15mm) or laser drilling.
5. Surface Treatment: Common processes include immersion gold (wear-resistant, good solderability) or lead-free tin plating (environmentally friendly).