Experimental Study On Localized Au Coating By Laser Induced Electrodeposition Based On Metal Surface

Precious metal coatings represented by Au are widely used in the electronic component industry because of their excellent stability,conductivity,weldability,corrosion and high temperature resistance.Typical application scenarios include the surface treatment of electronic device connectors,local plating points of mobile phone motherboard,solder joints(plates)and other structures,which can improve the service stability and service life of the product while maintaining the good conductivity and beauty of the product.In this dissertation,laser is introduced into the electrodeposition system to realize maskless localized electrodeposition of Au coating on the surface of metal substrate.The main research contents and results are as follows:1.The mechanism of laser-induced electrodeposition of metal matrix was studied.(1)Analysis of the gain effect of laser on metal electrodeposition process;(2)Study on the mechanism of laser thermal effect on electrochemistry,electrocrystallization and liquid phase mass transfer in induced electrodeposition;(3)Analysis of laser force effect on alleviating concentration polarization and improving surface quality;(4)The simulation model of laser-induced electrodeposition is established,the thermal inoculation effect of laser is simulated,and the variation law of electrodeposition process under laser irradiation is calculated and analyzed.2.According to the mechanism of laser-induced electrodeposition on the surface of metal substrate,the experiment of laser-induced electrodeposition of Au layer on Ni sheet was carried out.Firstly,the electrical parameters,laser parameters and solution thickness in the test system are pre-analyzed,and the reasonable ranges of test parameters are obtained,which realize the preparation of laser-induced local electrodeposition of Au coating.Then the effects of laser parameters on the surface of Au coating were studied by single factor test,including electrodeposition rate,surface morphology,element content,dimensional accuracy,corrosion resistance,matrix adhesion and internal structure.The typical pattern preparation and controllable adjustment of electrodeposited Au were realized.We studied the thermal diffusion effect of laser,then realized the induced-electrodeposition on the back of the thin plate and on the borehole wall inside the hole part.When the laser single pulse energy is 6μJ,the frequency is 2500 k Hz and the scanning rate is 2000 mm/s,the comprehensive performance of the coating is the best.3.Based on the realization of laser-induced electrodeposition on the surface of Ni sheet,the electrodeposition on the surface of 316 L stainless steel covered with dense oxide film was further studied.Firstly,the integrated process mechanism of laser removal of oxide film on 316 L stainless steel and induced-electrodeposition was analyzed and verified by experiments.Then,the effects of different laser parameters(laser energy,laser pulse frequency,laser scanning rate,laser scanning line spacing and pulse width)on the coating were studied through the single factor test.The comparative test of coating surface morphology,element content and dimensional accuracy were completed,and the parameters were optimized.The service performance of the coating prepared with the optimized parameters was strictly tested,including corrosion resistance,adhesion,welding performance and microhardness.The test results showed that the local Au coating electrodeposited on the surface of316 L stainless steel induced by laser met the requirements of the actual working conditions of the product.In summary,the topic is based on the research of local electrodeposition Au process of complex electronic components.Laser is introduced into the electrodeposition system to realize maskless laser direct writing inducedelectrodeposition.Local Au coatings meeting the service conditions are prepared on two common materials(Ni and 316 L stainless steel),which provide new ideas and processes for localized electrodeposition of Au structure and coating in the electronic industry,and has broad industrial prospects and important application value.