Will ultrasonics damage components of a populated misprint?
When ultrasonics was first developed in the 1950s, the technology was very crude and uncontrollable and the PCBs were very cumbersome and delicate. The two technologies were not compatible. Delicate wire bonds would break because of the low (20-25 kHz) and constant frequencies that were used. The lower the frequency, the more aggressive the ultrasonic cleaning action.
Today's ultrasonic systems are the most controllable precision cleaning technology available. The user can control virtually every parameter. In addition, today's PCBs are very compact and durable. The two technologies are now very compatible. Many Smart Sonic customers clean double-sided misprints with their ultrasonic stencil cleaner.
When cleaning populated misprints, frequencies should be kept at 40 KHz or higher (the lower the frequency, the more aggressive the cleaning action) and ultrasonic power (power density) should be kept at a minimum. Because of the efficiency of 440-R SMT Detergent, Smart Sonic does not need to use high-powered ultrasonic energy. Research indicates that ultrasonic power should be approximately 10 watts per liter of wash solution. Smart Sonic systems are able to clean effectively at less than 10 watts per liter of wash solution, assuring the utmost safety for populated assemblies. [Total power of ultrasonic energy (watts) / Total capacity of wash tank solution (liters) = Total watts/liter]
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