After working for a long time, there will be a large amount of solder paste attached to the surface of the stencil. And the solder paste is corrosive, if not removed in time, it will lead to stencil deformation, damage or fracture, and the accuracy will be reduced. If businessmen use ultrasonic cleaning machine to clean the stencil, these hidden dangers can be avoided.
Ultrasonic cleaning is the use of ultrasonic cavitation in the liquid, acceleration and direct current, direct and indirect cleaning of dirt, so that the dirt layer dispersion, emulsification, stripping, to achieve the purpose of cleaning. In the current use of ultrasonic stencil cleaning machine, the use of more cavitation and direct into the flow.
1、the role of cavitation
Ultrasonic cavitation (cavitation effect) refers to the existence of micro gas nuclei in the liquid cavitation bubble vibration under the action of sound waves, when the sound pressure reaches a certain value of the growth and collapse of the kinetic process.
Ultrasonic action on the liquid can produce a large number of small bubbles . One reason is the local tensile stress in the liquid and the formation of negative pressure, the reduction in pressure so that the original dissolved in the liquid gas supersaturation, and escape from the liquid, becoming a small bubble. Another reason is the strong tensile stress on the liquid “tear” into a cavity, known as cavitation.
2、direct flow into the role of
Ultrasound in the liquid along the direction of sound propagation to produce the flow of the phenomenon known as straight into the flow. The sound intensity in 0.5W/cm2, the naked eye can see the straight into the flow, perpendicular to the vibration surface to produce flow, the flow rate of about 10cm / s. Through this straight into the flow so that the surface of the cleaned object micro-oil dirt is agitated, dirt surface cleaning fluid also produces convection, dissolved dirt dissolved liquid and new liquid mixture, so that the dissolution speed is accelerated, plays a great role in the handling of dirt.
Liquid particles to push the acceleration generated. For the higher frequency of ultrasonic cleaning machine, cavitation is not significant, this time the cleaning mainly relies on the acceleration of liquid particles under the action of ultrasound impact particles on the dirt for ultra-precise cleaning.