A new microetchant and formulation for high density printed circuit board were developed. Based on the stability, etching rate of the microetchant, the surface brightness and roughness after etching, the microetchant was mainly consist of sulfuric acid and hydrogen peroxide. The amount of cleaning agents, brighteners, organic solvents, stabilizers and the reaction temperature were also determined. It can make the surface of the circuit board bright and rough. The affinity of metal surface and dry film can be improved. The rate of etching was high, stable and controlled and it can be used on PCB large scale production.