Study On Chromium-free Etching Progress Of ABS Resin Metallization Pretreatment

ABS resin is a thermoplastic plastic formed by copolymerization of three monomers,Acrylonitrile,Butadiene and Styrene.It is not electrically conductive and exhibits significant water repellency.The surface lacks active groups and cannot induce metal deposition,therefore,before the metalization of ABS resin,the necessary pretreatment should be performed to modify the resin surface.At present,the Cr O₃/H₂SO₄ micro-erosion system is used in industrial production,which causes persistent pollution to the environment and is highly carcinogenic to the health of the body.This paper proposes two new chromium-free micro-etching systems,Na₂S₂O₈/H₂O₂ and K₂Fe O₄,to provide potential solutions for replacing the traditional Cr O₃/H₂SO₄ micro-etching system.In this paper,the effects of the molar concentration ratio of Na₂S₂O₈ to H₂O₂,micro-etching temperature and micro-etching time on the micro-etching effect and coating properties of the ABS resin surface in the Na₂S₂O₈/H₂O₂ micro-etching system were first studied.In the Na₂S₂O₈/H₂O₂ system,when the Na₂S₂O₈/H₂O₂ ratio is 1:1,that is,Na₂S₂O₈ 45 g/L,H₂O₂21.42 g/L,Fe SO₄·7H₂O 61.29 g/L,C₆H₈O₇ 59.53 g/L,the open circuit potential of the solution is 0.527V.After the micro-etching temperature was 60°C and the micro-etching time was 10minutes,a large number of micropores appeared on the surface of the ABS resin through a scanning electron microscope,and the pore diameter was uniform and had a certain depth.The surface hydrophilicity has been significantly improved,with a contact angle of 56.5°.After activation,the starting time and plating time of electroless nickel plating were 7.8 s and 25.4 s,respectively.The bonding strength between the ABS resin matrix and the electroless nickel plating layer is 2.07 MPa.The self-corrosion current density of the electroless nickel plating layer on the surface of ABS is 5.638×10^-7 A·cm^-2.Secondly,the K₂Fe O₄ concentration in the K₂Fe O₄ micro-etching system,the p H of the micro-etching solution,the micro-etching temperature and the micro-etching time were used to investigate the micro-etching effect and the coating performance of the ABS resin surface.The concentration of K₂Fe O₄ in the micro-etching solution is 10 g/L,the p H is 5,and the open circuit potential of the solution is about 0.523 V.When the micro-etching temperature is 60℃and the micro-etching time is 3 min,a large number of micropores appear on the surface of the ABS resin.The pore size is uniform and has a certain depth.The surface hydrophilicity has been significantly improved,with a contact angle of 64.54°.After activation,the starting time and plating time of electroless nickel plating were 6.2 s and 29.4 s,respectively.The bond strength between the ABS resin matrix and the electroless nickel plating layer is 1.83 MPa.The K₂Fe O₄ micro-etching system is green and environmentally friendly,and has a small amount of solute.It can obtain a good micro-etching effect under a short micro-etching time,and has a good application prospect in the field of ABS resin chrome-free micro-etching.