Research On The Influence Of Additives On Double Reduction Chemical Copper Plating Syste

As one of the engineering plastics,polyacrylonitrile-butadiene-styrene copolymer（ABS）had excellent properties of good high temperature resistance and good stability.In order to increase the performance of ABS and expand its application range,the surface metallization of ABS could be carried out.Electroplating and electroless plating were two common surface treatment technologies.Compared with electroplating,electroless plating had attracted more and more attention because of its simple process,energy saving and environmental protection.Formaldehyde had been widely used in the electroless copper plating system because of its excellent reduction ability.However,in recent years,with the enhancement of people’s awareness of environmental protection,the study of non-formaldehyde electroless copper plating system was one of the hotspots of contemporary electroless copper plating.The low cost and relatively safe properties of hypophosphite attracted people to study and develop the electroless copper plating system of sodium hypophosphite（SHP）.Because of the relatively weak reducing ability of sodium hypophosphite,the coating on the surface of the plastic substrate was thin after electroless copper plating.In order to improve the reduction performance of SHP electroless plating solution and further improve the use efficiency of the bath,borane dimethylamine complex（DMAB）,an auxiliary reductant,was added to the bath to continue the electroless copper plating process under the condition of keeping stability of the bath.By studying the effects of different additives on the electroless copper plating system,the suitable additive ratio in the double reduction electroless copper plating system was obtained.The main research contents of this manuscript were as follows:1.Double reducing agent SHP and DMAB were used in the electroless copper plating system.The effects of compound concentration of two reducing agents on electroless copper plating on ABS were studied.By using the grid design method,the suitable concentration ratio of two reductants in electroless copper plating system was discussed,and the corresponding deposition rate was determined.the micro-morphology and composition of electroless copper layer were characterized by field emission scanning electron microscope（SEM）and X-ray energy spectrum analyzer.The results showed that when the concentration of DMAB and SHP was 0.50 g·L^-1 and 90g·L^-1 respectively,DMAB and SHP had a good synergistic effect,and the deposition rate of electroless copper plating solution was the highest,which was 3.14μm·h^-1.The copper grains on the surface of the electroless copper plating layer were compact,the surface was smooth,and the copper content in the layer reached to 97.4%.On this basis,the experimental conditions of double reducing electroless copper plating system were determined by exploring the effects of temperature,plating time and p H on the basic electroless copper plating system.And the suitable double reducing electroless copper plating conditions were that the plating temperature was 75℃,p H was 9.0,and the plating time was 1h.At this conditions,the stability of the double reducing basic electroless copper plating system was good,and the deposition rate was the fastest.2.The effects of saccharin sodium and 2,6-diaminopyridine on the deposition rate and surface morphology of electroless copper plating were investigated and compared.The micro-morphology of electroless copper coating was characterized by SEM.The effects of these two accelerators on double reducer being oxidation and copper ion being reduction in electroless copper plating system were analyzed by polarization curve test.The results showed that the deposition rate was higher than that of2,6-diaminopyridine when the saccharin sodium was as accelerator.When saccharin sodium content was 0.2 g·L^-1,the deposition rate reached 4.08μm·h^-1.The surface of the deposited copper layer was smooth,which showed that 0.2 g·L^-1 saccharin sodium could effectively promote the oxidation process of reducing agent and improve the deposition rate.3.Potassium ferricyanide,potassium iodate,sodium sulfite and sodium3-mercapto-1-propane sulfonate（MPS）were added as stabilizers to double reducing basic electroless copper plating system.And the effects of different stabilizers on the deposition rate and surface morphology of electroless copper plating were investigate.The micro-morphology of electroless copper coating was characterized by SEM.The effects of these stabilizers on the double reductant being oxidation and copper ion being reduction in electroless copper plating system were analyzed by polarization curve test.The results showed that the deposition rate was lower than that of other stabilizers when MPS was stabilizer in double reducing electroless copper plating system.When MPS content was 3 mg·L^-1,the deposition rate was 0.569μm·h^-1,which indicated that MPS had a strong inhibitory effect on the reducibility of electroless copper plating system.4.Saccharin sodium and MPS were selected as accelerator and stabilizer respectively in the double reducing basic electroless copper plating system.And the synergistic effects of the two additives on the deposition rate and surface morphology of electroless copper plating were explored.The micro-morphology of electroless copper coating was characterized by SEM.The effects of these two additives on double reductant being oxidation and copper ion being reduction in double reducing basic electroless copper plating solution were analyzed by polarization curve test.The results showed that the deposition rate reached 3.63μm·h^-1,and the copper grains on the surface of the electroless copper plating layer were compact and smooth when 0.2 g·L^-1saccharin sodium and 2 mg·L^-1 MPS were added to the double reducing basic electroless copper plating system.On this basis,nickel sulfate hexahydrate was added to the electroless copper plating system as stress relieving agent.And the internal stresses of（220）and（311）crystal planes of copper films were measured by X-ray diffraction.The results showed that the internal stress of electroless copper plating film could be decreased by adding Ni SO₄·6H₂O to the electroless copper plating system.The minimum stress of electroless copper plating film was-72 MPa when the content of Ni SO₄·6H₂O was 0.3 g·L^-1.