Zou, L; Hunt, C (2007) Test method for conformal coating protection performance of electronic assembly in harsh environments. NPL Report. DEPC-MPR 060

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Abstract

This report describes new developments for a test method for assessing conformal coating protection performance on electronic assemblies using the Surface Insulation Resistance (SIR) technique. The new method is significantly different to the existing standard1 in a number respects and reflects more realistic application of conformal coatings. A new test assembly is introduced with a wide range of components, and has many advantages in identifying coating protection problems. The procedure on how to chose and apply contaminants to test coupons to simulate the contaminants effect from harsh environments on underlying circuit reliability is detailed in the method. The test parameter settings for SIR test and SO2 exposure testing are given. The test method provides a measurement tool to discriminate between coatings.
The use of this method to investigate the protection performance of seven different types of coatings (two water-based acrylics, solvent-based acrylic, fluoroacrylate, silicone, polyurethane, and epoxy) against solvent-based flux, surfactant and SO2 gas, is included in an appendix. These results demonstrate that SIR technique is a suitable discriminatory tool for coating performance assessed, and is sensitive in detecting the circuit reliability underneath coatings. Coating type affects the level of protection against specific contaminants i.e. coatings are contaminant-sensitive. Coating protection performance is not only dependent on coating and contaminant type, but also the component type where shape factor and coating coverage is an issue. Therefore, the results on protection performance of conformal coating using this new test method and test board design provides more realistic and useful information on the protection performance of conformal coating against specific harsh environment in which electronic circuits operate.

Item Type:	Report/Guide (NPL Report)
NPL Report No.:	DEPC-MPR 060
Subjects:	Advanced Materials Advanced Materials > Electronics Interconnection
Last Modified:	02 Feb 2018 13:15
URI:	http://eprintspublications.npl.co.uk/id/eprint/3870

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