ULTRASONIC CLEANING FOR PCB APPLICATIONS
An Ultrasonic Cleaner comprises of a tank (with different sizes), motor/ circuit and a removable basket / tray. To begin the cleaning process, the cleaning tank is filled with water or a cleaning solution. Cleaning solutions can consist of non-ionic surfactants & detergents.. You can then place the PCBs in a small basket and place that basket inside the tank.
When you switch on the machine, ultrasound waves and chemicals combined to create bubbles that "cling" to the foreign particles such as dirt, oil, Flux and unknown substances. The high frequency waves are sent out and pull the contaminants off of the object. The vibrating motion of the ultrasonic waves creates tiny bubbles in the water known as cavitation; millions of these bubbles rubs against each-other and into the object resting in the cleaning tank. This cavitation process gently knocks dirt & stain off the object. The motion is very effective at penetrating the tiny crevices which is not possible via human hand or by dunking the instrument in water/ chemical alone.
The Ultrasonic Cleaning Cycle time for most processes is approximately 3-5 Minutes depending upon the quantity of objects placed in the basket as well as the level of contamination of the same. Once you set the timer, the machine does its work in few minutes and the dirt now rests in the bottom of the tank. The cavitation effect blasts the particles off the PCB’s surface and leaves them in the solution. You can now remove the basket along with the PCB.
STEPS OF CLEANING PCB USING ULTRASONIC CLEANING MACHINE
Choosing the correct Ultrasonic Cleaning Machine
You will not only have to choose the correct size of the Ultrasonic cleaner, but you will also have to suggest your ultrasonic provider with quantity of PCBs that you will be cleaning in a day. If you wish to clean PCBs in thousands of quantities in a day or large volumes then you would be required to use a more robust & industrial heavy duty ultrasonic cleaner with multiple tanks or chambers. This type of machines will be a custom-built system and would be suitable for your operation. Such machines would often have a drying system along with them.
If however you are limited to cleaning a few pieces of PCBs in a day, much like repair purposes, then we recommend taking a table top Ultrasonic cleaner according to the size of the PCBs that you wish to clean. Table Top Ultrasonic cleaning machines are light duty & easy to carry machines which are convenient to use and are single tank counted top units. However please be noted that table top Ultrasonic cleaning machines requires rest of few minutes between long working hours are thus they are not suitable for cleaning large volumes of PCBs in a day.
Choosing the correct Cleaning Chemical
| Choosing the correct Cleaning Chemical |
IPA / ISO-PROPYL ACOHOL
Traditionally, IPA or Iso-propyl alcohol is widely and popularly used for cleaning of PCB / Printed Circuit Boards. Ideally using IPA as a cleaner is “OK” with some precautions as under:
- When you are using IPA with a brush to clean the PCBs.
- When you are using an Ultrasonic Cleaner with a capacity of “no more than a 2 Liter”; with a precaution to not use Heating Element of the machine. Keeping the environment well ventilated. Strictly keeping no open switches / and fire proof zone with no open flames around. Keeping a Fire Extinguisher near the machine facility for added security.
When using IPA; the volatile nature of the IPA prevents its usage in larger volumes. Not only it is dangerous due to its propensity to catch fire quickly, but it’s vapors are also unhealthy for the user who is exposed to them. We recommend using IPA in limited quantity and with extreme and utmost precautions.
WATER SOLUABLE CHEMICAL – RKT PCB CLEANER
We offer a safer and non-flammable alternative to IPA. Our specially crafted PCB cleaning solution is ideal for removing flux , dirt, dust, rust and other foreign contaminants form the PCB boards. One litre of RKT PCB CLEANER is to be diluted with three litres of water before use. For better results the diluted solution taken in wash tank preferably warm and component must be dipped with constant agitation of Ultrasonics. When the action of solution slows down and the solution becomes thick, dark brown and now is the time to replace the solvent.
The PCB (Printed Circuit Board) already soldered or the PCB which has to be cleaned (flux residue or other elements on PCB) must be cleaned by adding 3-4 litre water (RO/DM water preferred) in 1 litre of concentrated RKT PCB CLEANER. 5 litre of the following solution must be taken in a tray and PCB must be dipped in it for a specific time. As we takeout PCB from the solution, timing increases.For example: If we soak PCB in the solution for 5 minutes in first try, it must be soaked for 7-8 minutes the second time. Time Increases in further dips. (7 mins to 10 mins then 15mins and further on till board gets cleaned completely).
After some soaks, as the flux residue gets cleaned, the solution upgrades brownish colour and solution becomes slightly thick(viscous). At such time, this used solution must be discarded and new solution must be used for further process.After the PCB is completely cleaned, it must be directly taken to wash basin. Rinse with tap water. (Borewell or ground water must be ignored).
Use of more amount of water is recommended so that no remains of RKT PCB CLEANER are left on PCB. It turns PCB black.
Tips and Hints of cleaning PCBs with RKT PCB CLEANER:-
- RKT PCB cleaner which is only suitable for sealed component as well as SMD, diodes, resisters, condensers, transistors, ICS, IC-sockets, etc.
- These are not safe for mount component.
Eg : transformers, relays,etc.
- If PCB does not react (badly) with water, if such components are present on the PCB, there is no doubt to use PCB cleaner.
- After cleaning PCB with RKT PCB CLEANER, board will become clear and clean.
- Large amount of water must be used to clean the board(Tap water recommended).
- Given time period for PCB cleaning and dilution of chemical depends upon the PCB(flux residue and other components to be cleaned).
