Research On Wetting Mechanism Of Soft Solder On Glass Surface

The connections between the glass has been widely used in electronics,machinery, aerospace aspects, it needs coating process if we want to realize theconnection with glass at low temperature under280℃, but both atmosphericand vacuum coating process, coating defects are inevitable. In the process ofcoating processing, scratch, pinhole, film uneven local defects often affects thequality of the coating, then it affects the welding quality, so there are someproblems with welding after metalizing. The main research content of this articleis realizing the direct connection under280℃between glass.So in this article, analysising of glass surface condition and elementthrough the method of combining experiment and theory influences onwettability and the reason of the poor wettability. It finally realizes the lowtemperature direct wetting on glass surface with soft solder volatile elementszinc, and change the interfacial tension.Testing the wettability after metalizing on the glass. We realize theconnection between glass in low temperature when the glass was coated gol dand nickel. The results found that with the increase of film thickness and coatinglayer defect reduction the solder has better solubility on the laye, the minimumwetting Angle can be up to28.8°。Gold plated film test results show that whenthe adhesion strength of the coating and the substrate is less than5N and thecoating thickness less than1.5μm, solder appears to not wetting phenomenon;When binding force growth to37N, wetting angle decreases to11.80°alongwith the growth of the wetting time, the root cause of the wetting angledecreases is fully dissolve with Au in the solder.Analysis of solder at low temperature directly wettability on the surface ofthe glass. This article uses the In-Sn solder test wettability on sodium calciumsilicon glass, ground glass and sodium borosilicate glass surface, these all showno wetting state。We performed for three types of glass with1000#sand discgrinding and HF acid pickling to change its surface state, while the wettingangle is still greater than90°, Wenzel equation combined with AFM resultshows that the reason of decline of wetting angle is caused by droplets toovercome its surface uneven barrier needed different energy. At the temperature180℃,by the Young’s equation cosθ<0，namely solder on the glass surface nowetting.Using Sn-20Zn solder containing volatile elements Zn proceeds wetting experiments in vacuum condition.The results show that Zn formed partial gatherin the interface due to Zn has a tendency to evaporate under vacuumcondition,this phenomenon leds to wet on glass surface because of affecting theinterfacial tension and also increasing the driving force. Wetting angle is just16.62°. Glass and solder closely contact form a flat interface and the solderstructure changes before and after wetting,Zn appears partial gather phenomenonin the interface and it generates dark gray phase while the original black acicularstructure decreased significantly in the solder. Analysising the reasons ofwetting angle decreases by the point of view of thermodynamics and dynamics.The difference of chemical potential contributed to the Zn partial together, itdecreases the solder surface tension, sped up the move velocity of three phaseline, increase wetting driver, and finally realizing the wetting.