The Effect Of Conformal Coatings On Thermal Infrared Profiles Of Printed Circuit Boards

Herbert Kaplan

doi:10.1117/12.940505

Abstract

Conformal coatings are applied to most printed circuit boards (PCB's) in use on military programs. They are clear, transparent (to visible light) coatings that help reduce the mechanical effects of vibration and protect the PCB's from moisture and fungus under adverse environmental conditions. It has been a commonly held belief for some time that, from the point of view of thermal imaging, conformal coatings tend to have a high and uniform emissivity in the infrared spectrum and, therefore, provide the PCB's with very close to "blackbody" infrared characteristics. This belief has been challenged recently by investigators who observed indications that MIL specified conformal coatings had far from blackbody characteristics. These characteristics were reported to vary with type, thickness and the wavelength interval (spectral band) measured. In 1985 the US Army Communication Electronics Command (CECOM) initiated the TRAMS (Infrared Automatic Mass Screening) program aimed at the automatic mass screening of PCB's for gross faults at the depot level based on infrared profiles. A conformal coatings investigation was conducted as part of the IRAMS program in order to achieve a better understanding of the effects of conformal coatings on the infrared thermal profiles of PCB's. Predictive investigation was conducted through contact and correspondence with manufacturers and users of conformal coatings. Experimental investigation was conducted by means of measurements using imaging systems operating in different wavelengths and prepared samples with various conformal coating types and thicknesses. This paper describes the work done, the results obtained and recommendations for future measurements.

Citation Download Citation

Herbert Kaplan, Herbert Kaplan, "The Effect Of Conformal Coatings On Thermal Infrared Profiles Of Printed Circuit Boards", Proc. SPIE 0780, Thermosense IX: Thermal Infrared Sensing for Diagnostics and Control, (11 May 1987); doi: 10.1117/12.940505; https://doi.org/10.1117/12.940505

ACCESS THE FULL ARTICLE

PERSONAL SIGN IN
Full access may be available with your subscription

Email or Username Forgot your username?

Password Forgot your password?

Show

Remember Email/Username on this computer

Remember Password

No SPIE account? Create an account
or Institutional Sign In via Shibboleth

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available

Members: $14.40

Non-members: $18.00 ADD TO CART

Show All Keywords

Keywords/Phrases

Search In:

Publication Years