Etching of Polycarbonate Surface by KMnO₄-H₂SO₄-H₂O System

In order to improve the surface adhesion strength between polycarbonate (PC) and coating, the surface of PC was etched by KMnO₄-H₂SO₄-H₂O system, and copper coating was prepared on PC surface. The effects of sulfuric acid volume fraction and etching time on the surface morphology, hydrophilicity and adhesion strength between PC and copper coating were studied by scanning electron microscopy, video optical contact angle measuring instrument and universal material testing machine. The results show that the PC substrate obtained excellent surface roughness and hydrophilicity after etching by KMnO₄-H₂SO₄-H₂O system. At the same time the copper coating was firmly bonded with the substrate. After the PC was etched for 25 min under conditions of 70 ℃, 6 g/L KMnO₄ and volume fraction of sulfuric acid of 71.0%, a large number of dense and uniform micropores were formed on the surface of PC substrate, and the surface roughness of PC increased, which provided a good fixing point for copper deposition during electroless copper plating. Moreover, the contact angle of PC surface was reduced from 83.5° to 53.7°, the hydrophilicity was greatly enhanced, and the adhesion strength reached a maximum of 4.1 N/cm.