Silicone coating removal

[aditronics]

Please suggest, different methods to remove Silicone coating.And is there any solution to remove the same?

Kindly suggest any links having videos that shows the procedure to remove the same.

 

[jpanhalt]

When you refer to silicone, I am assuming you are referring to silicone rubber, adhesive, or sealant, not to silicone oil or grease. Silicone oil and grease are relatively easy to remove. As for removing polymerized silicone rubber, that is considerably harder.

So far as I know, there is no solvent for the rubber. I believe GE has stated the same. That leaves mechanical removal and denaturing the rubber as the only two options.

Mechanical removal involves scraping, cutting, etc. It is tedious. I have found that a mixture of isopropyl alcohol (99% or more)and light mineral spirits (such as VM&P naptha) -- the ratio is not critical -- helps as a lubricant. And, once the solvent penetrates the rubber, that mixture helps break the bonds to whatever the substrate is. 3M abrasive pads also help. I use a fine (white or gray) pad. If done carefully, you can avoid major scratching of the substrate. (The longer chain alcohol and naptha help, see discussion below.)

As for getting the rubber off chemically, I have found only one type of commercial product that works. The chemical basis of those products is a long chain aliphatic sulfonic acid. The aliphatic chain helps the chemical penetrate the hydrophobic silicone gel; the sulfonic acid (a strong acid) denatures the bond to substrate. It also degrades the rubber. Here is a link to one brand that is based on that chemistry: https://www.amazon.com/home-improvement/dp/B000PVSVW8 For more information on the chemistry, check the MSDS. There is another brand available in the USA that uses a more chemically defined sulfonic acid, but I can't recall its name just now. Either brand will take several hours to work.

Of course, your substrate needs to be resistant to acid, if you use the latter products. They work well on ceramic, plastic (e.g., fiberglass tub enclosures), and some metals, probably copper and stainless steel. More active metals, such as aluminum, might be a problem. Some plastics may show crazing if you use the product on them.

John

 

[aditronics]

sorry,John i am asking about Sillicone conformal coating on PCBs.Do you know any techniques to remove it???

 

[FvM]

Silicone conformal coating is cured silicone rubber as well. So the comment about applicable solvents applies for it in he same way. Thinner coating might help a bit.

 

[tpetar]

Silicone solvent
http://www.valco-cp.com/solvent200.htm


Best regards,
Peter

:wink:

 

[FvM]

As for getting the rubber off chemically, I have found only one type of commercial product that works. The chemical basis of those products is a long chain aliphatic sulfonic acid. The aliphatic chain helps the chemical penetrate the hydrophobic silicone gel; the sulfonic acid (a strong acid) denatures the bond to substrate. It also degrades the rubber. Here is a link to one brand that is based on that chemistry: http://www.amazon.com/home-improvement/dp/B000PVSVW8 For more information on the chemistry, check the MSDS. There is another brand available in the USA that uses a more chemically defined sulfonic acid, but I can't recall its name just now. Either brand will take several hours to work.

Dow Corning DS-2025 is based on the same chemistry. http://www.dowcorning.com/applications/search/products/Details.aspx?prod=04089120&type=MATL

Silicone solvent
http://www.valco-cp.com/solvent200.htm

Sounds interesting. At least siloxanes aren't very chemical agressive.

I also found an article discussing "silicone digestive" compounds.