| Printed circuit board(PCB)provides an essential channel for electrical interconnection of electronic components.With the development of Internet-ofEverything,AI technology and the fifth generation wireless technology,the manufacture process of the PCB has made huge progress.At present,copper etching is the main technology of PCB interconnection circuits manufacturing,and electroplating tin on copper to protect circuits from corrosion during the copper etching process is the key to make high-quality electronic circuits.Therefore,the research of modification for tin layer on the surface of PCB interconnection circuits has important scientific value and application prospects for improving PCB manufacturing technology and facilitating 5G communication.Plating tin on PCB interconnection circuits substantially is electrodepositing tin on the copper surface.And additives could have an impact on the tin crystallization condition and coating properties by influencing the critical steps of electroplating tin.There are some coating quality problems such as pinhole,porous and black coating in PCB manufacturing enterprises,to solve the issue,three brighteners were selected and their effect on the process of electroplating tin on copper were studied.The research contents are shown as follows specifically:(1)Vanillin and its derivatives were selected as brighteners for electroplating tin.The action mechanism of the three brighteners and the relationship between the molecular structure and the mechanism were studied through quantum chemical calculation and molecular dynamics simulation.Study found that three brighteners all have high molecular reactivity,and they could spontaneously absorb on the tin layer with the absorption site of oxygen atom of aldehyde carbonyl,which is related to the brightener molecular structure.In addition,strong adsorption of ethyl vanillin on the surface of tin(211)was found.(2)Based on the result of the numerical simulation,the effects of three brighteners on the process of electroplating tin were studied further by electroplating experiment,electrochemical test,corrosion resistance test and so on.It was found that all the three brighteners could have an inhibiting effect on the process of electroplating tin,and they could also change the density,uniformity and crystal orientation of the tin coating.Among them,the inhibiting effect of ethyl vanillin was the strongest and the obtained coating had the best density,lowest porosity and best corrosion resistance.The results also showed that the crystal surface of tin(211)is not conducive to the improvement of corrosion resistance.In addition,the result of technological conditions optimization indicated that the optimal concentration of the three brighteners was 100mg/L,100mg/L and 150mg/L,respectively.(3)In view of the shortcomings of existing PCB manufacturing technology,an innovative application of tin coating in PCB manufacturing was proposed in this paper,which takes the growth of tin seed layer and copper electroplating as the key points.Application experiments implemented in the substrate of ethylene-propylene-diene,and the test method mainly are coating microstructure test,metallographic microscope test,energy spectrum analysis,and peel strength test.The results showed that the conductive circuits were complete,the lateral erosion was slight,and the adhesion force between the circuits and the substrate was great with the peel strength of 0.86 N/mm.To sum up,this paper makes a comprehensive study on the mechanism and effect of the three brighteners on the process of electroplating tin,and puts forward a new technology for PCB interconnection circuits manufacturing.Some of the research results have been applied in enterprise production,and good economic benefits have been obtained. |
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