How to Clean and Restore Mobile Devices and PCBs

The Best Way to Clean PCBs

The PCB market is expected to reach an estimated $89.7 billion by 2024 with a CAGR of 4.3% from 2019 to 2024 according to a report by Lucintel.  Important to both manufacturing and maintaining PCBs is keeping them clean.  Delicate PCB circuitry is affected by contaminants introduced during fabrication and by exposure to moisture and other elements in daily use. This post explains why fabricators, computer and mobile device repair services use ultrasonic cleaners as the best way to clean PCBs. 

Why Ultrasonic Cleaning is the Best Way to Clean PCBs

If you manufacture PCBs, sell or repair mobile devices or other products utilizing printed circuit boards  an ultrasonic cleaner should be part of your equipment inventory. Unlike potentially damaging mechanical cleaning PCBs with brushes and solvents, these units use the power of ultrasonic cavitation  to quickly, thoroughly and safely remove contaminants from all surfaces immersed in a biodegradable ultrasonic cleaning solution.

How Fabricators Use Ultrasonic Cleaners as the Best Way to Clean PCBs

Elmaultrasonic offers a number of ultrasonic cleaners that are ideal for fabricators to clean PCBs.  Although we give a real-life example later in this post the process is rather straightforward:

  • Select an ultrasonic cleaner with a “Sweep” function to prevent potentially damaging harmonic vibrations.
  • Follow cleaning solution manufacturers’ instructions concerning diluting the concentrate, the correct cleaning temperature and estimates of cleaning time.
  • Fill the ultrasonic cleaning tank half way with water, add the correct amount of cleaning solution formulation for a full tank and continue adding water to the fill line. 
  • Turn on the unit without a load to mix and degas the solution.  Degassing removes air trapped in the liquid, which slows down the cleaning process.  Some units are equipped with a Degas mode to speed the process.
  • Place the printed circuit boards in a basket or rack in such a way that they do not contact each other.  When ready lower them into the solution.
  • At the end of the cycle remove and inspect.  When satisfied rinse the boards with de-ionized water to thoroughly remove cleaning solution residues and allow them to dry.  Large capacity fabricators may elect to employ electric dryers for this process.

For more on this see our post on how to select an ultrasonic cleaner.

What Cleaning Solution Should I Use for PCBs?

Two cleaning solution concentrates that can be used to remove water-soluble fluxes are the mildly alkaline elma tec clean A1 and neutral elma clean 260 d&s, the latter of which may be effective in removing some fluxes that are not water soluble.  You’ll find details on these and other formulations on our cleaning solutions formulations page.

You are also welcome to contact our scientists for recommendations based on your specific requirements.  Simply give us a call.

A Case Study on the Best Way to Clean PCBs

Here we share information on cleaning PCBs with ultrasonic cavitation as developed by IDC Technologies.  While it relates to cleaning hand-assembled circuit boards made with a water-soluble flux its value lies in the fact that the customer developed its best way to clean PCBs through experimentation.

IDC uses the dual-frequency, heater-equipped Elmasonic P180H model.  It was selected because the P series offers adjustable ultrasonic power that can be set from 30% to 100% of the P180H unit’s 330-watt effective power.  It also allows the operator to select either 37 kHz or the less aggressive 80 kHz ultrasonic frequency. 

The P line provides the critical Sweep mode to prevent harmonic vibrations that could damage delicate PCB electronics, and a Degas mode to drive off cavitation-inhibiting entrapped air.

IDC’s PCB Cleaning Steps

Boards are carefully positioned in the cleaning basket so they do not contact each other.  The ultrasonic cleaner is readied by turning on the generators which activate the Sweep mode, setting the thermostat to 30⁰C (86⁰F) and the power to 30%.  Set and actual values are displayed on the control panel.  When all is ready the basket is immersed in the solution and the timer set for 7 minutes. 

The 7-minute cleaning cycle may vary depending on the number of boards cleaned and their condition.  At the end of the cycle the basket is removed and the boards are rinsed using deionized water then air-dried under a fan. While the process in general is excellent for PCB cleaning it cannot be used when they contain sealed board-mounted relays.  

Selecting and Using an Ulatrasonic Cleaner for Mobile Devices

For cleaning mobile devices you should consider the ¾ gallon Elma Plus 30H or 1½ gallon E Plus 60H ultrasonic cleaners available from Elmaultrasonic. 

The Elma E Plus line is especially ideal for the job because units are equipped with an automatic Sweep mode that is very important to prevent damage to sensitive PCB assemblies, a heater to further improve the ultrasonic cleaning process, and a timer. 

A recommended cleaning solution is elma tec clean A1 as described on our cleaning solutions page referenced above.  It should be diluted 1:20 with water.  As suggested earlier in this post fresh solutions should be mixed and degassed.  For the E Plus units you accomplish this by activating the Pulse mode for a short period of time.

Here again are suggested procedures that you’ll refine with experience. 

  1. Set the temperature dial to 50˚C. 
  2. Place the disassembled mobile device in the mesh basket in such a way that components do not come in contact with each other.
  3. When the set temperature is reached the unit will start. Lower the basket into the solution and set the timer dial for 10 minutes.  The unit will automatically stop.
  4. Remove the components and inspect.  If clean, thoroughly rinse them with deionized water and let them dry.  They are now ready for reassembly.

Contact the experts at Tovatech for help on selecting and using ultrasonic cleaners and the correct cleaning solutions to add efficiency to your operations.