The conformal coating removal process
Posted by Sean Horn
Thursday, April 5, 2012 6:48
@ 6:48 AM
**Removing conformal coating typically involves very caustic chemicals that can potentially be damaging to the operators in the vicinity, are under strict control by local environmental organizations, and/or damaging to your product. It is highly recommended that you consult with a conformal coating professional before trying to remove conformal coating. Diamond-MT assumes no responsibility for the actions taken as a result of this information.**
How to remove conformal coating
Stripping of unwanted conformal coating from a PCB can be a simple process or a very messy difficult job. It depends on what coating you need to remove, where the coating is, and the type of components on the board.
It is necessary to first identify the coating that needs to be removed from the assembly. Once the coating has been identified, you will be able to determine the proper chemical stripper needed to dissolve the coating. It is recommended that you speak with a professional in the conformal coating industry to select your chemical.
Now that you have your chemical selected, it is time to determine just how much coating needs to be removed. The amount of coating that needs to be removed will greatly affect your choices for removal techniques. If it is just a select area that needs rework, gentle mechanical abrasion with the chemical stripper in the problem area will usually be enough to dissolve the coating.
If the entire board needs to stripped, it gets trickier. The board must be entirely immersed in the stripping fluid and agitated. The WS100 Stripping System greatly aids this process by combining multiple submersion tanks with the necessary agitation to ensure a successful removal.
A word of warning must be given here. First, when submerging in a stripping material check there are no compatibility issues with the PCB. Stripping fluid could attack plastic components and/or writing on the boards (such as serial number labels).
The other issue that can be a major headache with full stripping of a board is that because the coating re-dissolves into the conformal coating stripper, there will now be coating residue all over the PCB even (especially!) where you didn’t want it. This can be a real problem with certain components such as low profile connectors! To remove these residues you will need several tanks of stripping fluid and the PCB will need to be fully rinsed in each, gradually flushing the residue out of the wrong areas. Once completed the PCB should then be cleaned to remove any unwanted contamination.