How to Use an Ultrasonic Cleaner to Restore Electronics and PCBs

Dust, dirt and corrosion can impact the performance of printed circuit boards (PCBs) used in electronic equipment exemplified by sophisticated hand-held devices such as iPhones, multifunctional iPods and BlackBerrys. Here at Tovatech we receive calls asking how these devices, some of which have been accidently dunked, can be restored. Our recommendation is to use an ultrasonic cleaner  along with ultrasonic cleaning solutions especially formulated for delicate electronics.

Selecting an Ultrasonic Cleaner

Ultrasonic cleaners such as the Elmasonic E series are ideal for cleaning and restoring these electronic components.  Bench and tabletop Elmasonic units are offered in tank capacities up to 7 gallons of cleaning solution for use in electronics parts and service stores.  The E series operates at an ultrasonic frequency of 37 kHz (37,000 cycles per second) providing safe cavitation cleaning action that reaches all PCB and equipment housing surfaces.  Further protection is provided by the units’ automatic “Sweep” function that eliminates potentially damaging harmonic vibrations as well as standing waves of high and low cavitation energy in the bath while at the same time optimizing cleaning results.  All units have time and temperature controls.

For larger operations such as PCB manufacturing facilities, industrial-sized floor models equipped with PCB racks to hold multiple boards are available from Tovatech.

How to Select and Use the Cleaning Solution

The wrong cleaning solution, just as the wrong ultrasonic cleaning frequency, can do more harm than good.  An ultrasonic cleaning solution ideal for glass and ceramic substrates, optics, PCBs and plastic parts is the biodegradable concentrate elma tec clean A1 available in 2.5 liter containers. It removes grease, oil, activated fluxes, dust, fingerprints, light corrosion and residues from coffee, tea, colas, milk and other sources.

Depending on the extent of contamination this concentrate is diluted 3 – 10% with water.  The recommended ultrasonic cleaning time is 3 – 10 minutes at approximately 65˚C (150˚F).

Parts exhibiting more significant corrosion can be restored with elma tec clean S1, also available in 2.5 liter containers.  This is diluted 1 – 5% volume with water and used at 65˚C (150˚F) for approximately 2 minutes.  But first check to be sure the corrosion has not irreparably damaged the PCB.

After cleaning the parts must be rinsed in distilled or deionized water.  This is very important in order to remove any traces of cleaning solution residue.  Because tap water also will leave residue deposits it must not be used as a rinse.  Dry the components thoroughly before reassembly.

Note that these are only guidelines.  You should consult with the ultrasonic cleaning professionals at Tovatech regarding equipment, solutions and procedures to meet your requirements.

Other Suggestions

A fresh batch of ultrasonic cleaning solution contains entrapped air.  You can see evidence of this by the bubbles that appear on the inside of a glass of water standing at room temperature.  This air interferes with the cavitation process and must be driven off before you begin the cleaning operation.  To do this

• add water and the correct portion of cleaning concentrate to the tank’s fill line
• set the temperature dial
• turn on the ultrasonic cleaner to start the degassing operation

The rising temperature coupled with the cleaning chemicals and ultrasonic energy will speed the degassing operation and at the same time thoroughly mix the contents of the tank.

When air bubbles no longer rise to the surface you are ready to clean the parts.  Place them in the mesh basket, taking care to keep them from contacting each other.  Lower the basket into the cleaning solution and set the timer.

As you become experienced with ultrasonic cleaning PCBs and other electronic components you’ll become more proficient and efficient.  The scientists at Tovatech are ready to help you reach this goal by selecting the ultrasonic cleaner model, frequency, power and cleaning solution that meets your requirements.

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How do you clean printed circuit boards and other electronic components?  How long does the process take?