Parylene Coating Removal— 18 / 12 / 2018
Traditional conformal coating removal would use a recommended chemical treatment to effectively “strip” the coating from the parts. The use of chemical solvents or strippers is largely ineffective due to the high chemical resistance of Parylene coating. Considering that a chemical alternative to strip Parylene is not available, we must look into alternative methods.
Parylene coating removal falls into three categories.
1. Thermal removal
2. Mechanical removal by hand
3. Machine Abrasion
Parylene coating offers a relatively high heat resistance depending on the type of Parylene that has been applied. This can range from roughly 300C for Parylene C to nearly 500C for Parylene N. A high temperature oven can be utilized to “burn off” the Parylene on parts that will not be damaged by the heat. Wires, mandrels and cannulas are good examples for this technique.
A high temperature soldering iron may also be effective for localized removal of Parylene on circuit cards and other electronics. Both approaches can discolor the final product and may leave behind other undesirable residues.
This approach utilizes cutting, sanding, brushing, scraping and picking the areas of Parylene to be removed. This technique can be quite effective if the adhesion of the Parylene is poor. The biggest concern with this type of removal is the potential for damage to the final product. The need for experienced operators and lengthy removal time can make this a very expensive process. This approach is best suited for spot removal or component replacement. One the Parylene is removed the use of a liquid conformal coating may be required to “touch up” the area around the replaced component.
The use of a micro blasting system is the fastest and most cost-effective method to remove Parylene. This technique is useful for spot removal on IC’s or surface mount components along with total Parylene removal. The use of various blends of blast media is determined based on the type of product that requires Parylene removal.
This process is carried out in an ESD safe chamber which utilizes a vacuum and filtration to dispose of residual media and Parylene. Care must be taken to evenly remove the Parylene without spending too much time in one area. Trained operators use a hand-held stylus which allows the mixture of media to be targeted at the areas of Parylene to be removed.
What ever method of Parylene removal is decided upon, once the Parylene is removed a thorough cleaning must be carried out to ensure all of the particulate is removed. It is then recommended that Parylene is reapplied to ensure optimal protection is achieved.
Blog Written By: Dave Pribish- General Manager