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When Not to Use Acrylic Conformal Coating

Posted by Sean Horn

Wednesday, May 16, 2012 7:52

@ 7:52 AM

While acrylic conformal coating does have its many benefits, there are some applications whenever it is not the ideal conformal coating  to be using.  Typically in applications that have exposure to solvents, high temperature requirements, or require coating hardness, acrylic conformal coating should not be used.

 Solvent exposure

In applications that have an exposure to solvents, acrylic conformal coating is not the best choice.  Acrylic conformal coating can be removed with a weaker solvent such as isopropyl alcohol or xylene.  Whenever it faces even stronger solvents, it will not offer the protection that is needed, especially if your product is a mission critical device.  Other coatings, such as urethane or parylene conformal coating have a far better resistance to solvents than acrylics.

 High temperature requirements

For products that require a high temperature application, acrylic conformal coating will fall short of expectations.  For HumiSeal 1B31, arguably the most popular acrylic coating, the max continuous operating temperature is 125ºC.  Compare this to silicone conformal coating, whose operating temperature can exceed 200ºC.  For higher temperature requirements, silicone conformal coating will perform at a level that acrylics cannot.

 Coating hardness

For substrates that will face mechanical wear, acrylics will disappoint.  While they do have a better mechanical wear resistance than silicones, acrylics fall behind urethane and epoxy conformal coating in this category.

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