Specifically, we are discussing Low pressure plasma cleaning on this page.
We will answer questions frequently asked about plasma cleaning.
Parts are cleaned in Plasma mostly as preparation for further processes.
The objective being to improve bonding, paint adhesion or for further plasma surface treatment. This page includes a video which demonstrates plasma cleaning.
1.What are the advantages of low-pressure plasma cleaning?
1a. Compared to conventional cleaning methods.
- The control and repeatability.
- A small amount of clean gas is constantly feed into the chamber.
- No cleaning and washing fluids to be monitored.
- It’s a dry process.
- The wide range of contaminants that can be removed.
- Environmentally friendly. No wet-chemical fluids to be disposed.
1b. Compared to atmospheric plasma cleaning.
Whilst we offer both atmospheric and low-pressure plasma cleaners our focus is on low pressure or vacuum plasma cleaners.low pressure or vacuum plasma cleaners.
- The atmosphere in the chamber is controlled therefore recontamination can be avoided.
- The amount of cleaning gas is low. Sometimes it’s possible to simply use air.
- Due to the low pressure in the chamber there is no danger of fire or explosion when reactive gas is used, such as Hydrogen or oxygen.
- The exhaust doesn’t contain ozone.
2. What are the options I have?
There are basically three mechanisms at work in the chamber and depending on your application one, two or all three may be employed.
Additionally, conditions in the chamber are ideal for disinfection or sterilization.
This can be optimized by choosing conditions the generate high levels UV. We discuss this on a separate page.Plasma sterilization
Combinations of reactive plasma cleaning and sputtering for example can be extremely effective.
By employing reactive cleaning, the reduce the bond of contamination that is then removed mechanically by sputtering.
2a. Plasma cleaning by Sputtering:
Here molecules are accelerated to hit the product to be cleaned, a kind of micro sand blasting. Mechanically removing the contamination.
2b. Reactive plasma cleaning:
in which the gas in the cleaning chamber is chosen to react in its excited state with the contamination on the surface of the product. Gasses can be chosen to produce high levels of UV to accelerate the process.
2c. Baking -The use of elevated temperatures when plasma cleaning:
Special conditions are created in the chamber of the plasma cleaner to generate heat in the product to be cleaned.
Seldom discussed but extremely effective process.
Speeding up the process of removing volatiles.
Conversely by controlling the conditions during plasma cleaning heating and discoloring of the product is prevented.
This is mostly applicable to conductive materials.
An interesting almost by product is the fact that the ionized gas in the plasma chamber dissipates static enabling the easy removal of particles.
3. Which is correct process for my application?
3a. Plasma cleaning by Sputtering.
This is extremely good for removing contaminations that are relatively stable in a vacuum.
A good example is the removal of unwanted traces of lead that may be present on surfaces, or salts from dried fingerprints.
These may need to be mechanically removed.
Sputtering proves to be the ideals method to employ in such cases.
3b. Reactive plasma cleaning.
Often people talk about Oxygen plasma cleaners, but Oxygen is just one option.
It can have its problems in that surfaces can become discolored.
It is not the best option for cleaning Silver for example.
However, if the product is reasonably resistant to oxidization it is a good option.
There are several gasses that can be used instead of Oxygen, and these can be employed to remove oxidization on the surface of the product.
This method of cleaning is especially effective in breaking down and removing carbon-based contamination. (Oils etc.).
3c. Plasma cleaning at elevated temperatures. Baking
Out baking in a vacuum oven is a common practice.
This type of plasma cleaning can be very effective in removing volatile contamination.
Especially where the contamination has a long and difficult path to leave the product such as in tubing or cables.
Delivering heat to the products in vacuum can be slow and difficult.
Instead of heating overnight heat can be delivered almost instantly and be accurately controlled.
We have achieved temperatures high enough the melt copper in vacuum in a very short time.
4. How clean will my parts be after plasma cleaning?
I think the answer here is a question. How clean do you need to be? We have successfully supplied plasma cleaners and developed plasma cleaning processes that range from simply replacing and improving on ultra-sonic cleaning to what are probably the most demanding applications in the world for the electronics industry where contamination is measured by counting atoms and is so low it is on the limits of technology for determining the atomic % of contamination on a surface.
5. Can all materials be plasma cleaned?
No. Obviously they must withstand vacuum.
Materials that need to retain a high level of volatiles such as water cannot be cleaned.
Closed cell foams do not like vacuum.
However, the list that can be cleaned is long, from plastics, glass, metals to ceramics.
6. Is the form of my product a problem?
Mostly no. We have cleaned fine powders and even tiny diamonds up to large components and rolls of material.
There is room in our larger chambers for parts with volumes of 8000 liters and our modular plasma generators ensure the enough power is available to do the job.
The plasma cleans in even the smallest of crack and cavities.
The challenges can mostly be meet. Learn more about our plasma cleaners
7. How do I know if plasma cleaning is right for my products?
The best way is to contact us.
We will assist you in any way that is constructive to answer your questions.
This can take the form of advice as to if low pressure plasma cleaning is suitable and if yes, which system is best for your needs.
If possible, we will run trials for you.
In some more complex cases we will do process development.
We can perform contract cleaning until you decide.
We can look at renting a system to you for you to run trials or initial production.
Once you decide we can look at subtracting part of the rental cost from the purchase price.
Contact us to arrange to discuss your needs or concerns or simply phone us.
Arrange to have a sample treated.
We will be pleased to help: