| This paper mainly studied the spreading and wetting process of solder dropletunder the action of ultrasonic wave. Firstly, we analyzed the vibration distributionon the surface of50×30×3mm size5a06aluminum plate using ANSYS software.Due to the effect of reflection of the ultrasonic on the edge of the aluminum plate,the vibration in the middle of the plate is weak with the amplitude of6.39μm, andthe vibration in the edge of the plate is strong with the amplitude of15μm.The dynamic spreading process of solder droplet under the action of ultrasonicwave was studied with high-speed photography camera. When the ultrasonicamplitude is different, the spreading of solder droplet presents different forms.Atomization, ripples and the phenomenon of dynamic balance appears in thespreading process. Hereby, a simple physical model of the solder droplet spreadingunder the action of ultrasonic waves was proposed, and analyzed the influencefactors of solder droplet spreading under the action of ultrasonic, including surfacevibration strength, the base surface condition and solder physical condition.Solder droplet spreading behavior under the action of ultrasonic waves wassimulated with FLUENT software. When applying the ultrasonic waves, the internalpressure of solder droplet appears alternately, the maximum pressure could be up to1200kPa, solder particle vector moved with two trends which were outward andinward, the effect of ultrasonic amplitude and the wavelength numbers on30mmunderside was analyzed.The behavior of removing oxidation film was studied with Sn based solder andZn-5Al solder. At230℃, the oxide film wasn’t completely removed with Sn solderand Sn-4Cu solder. Zinc element could spread to the base metal during the processof heat preservation period. When the temperature reached to330℃, the oxidationfilm of the interface of Sn-4Cu solder and5A06aluminum was completely removed.After thickening of the oxide film with anodic oxidation, the oxide film of theinterface of Zn-5Al solder and5A06aluminum was partly removed, undercurrentand corrosion pits appeared in this condition. So that cavitations, the solubilitybetween solder and base metal and ultrasonic flow disturbance effect are the threekey factors which influence the removal of oxide film under the action of ultrasonicwaves. |
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