CIS Conformal Coating & Encapsulation 2

Question 1

What conformal coating defect is described as small circular depressions or craters that expose the underlying substrate?

Accepted Answer

Fisheye (cratering)

Answer

Fisheyes or cratering are circular depressions caused by surface tension differences, often from contamination or silicone, that pull the wet coating away from a point and expose the substrate.

Question 2

An 'orange peel' texture on a cured conformal coating surface is generally considered:

Accepted Answer

Acceptable in most cases per IPC-A-610

Answer

Orange peel texture is a cosmetic irregularity that does not impair the protective function of the coating and is generally listed as an acceptable condition in IPC-A-610.

Question 3

Which condition would constitute a defect in conformal coating per IPC-A-610 for Class 2 and Class 3 assemblies?

Accepted Answer

Exposed conductors or solder connections that are required to be coated

Answer

Exposed conductors, lands, or solder connections that should be coated leave the circuit unprotected, directly violating the protective requirement and constituting a defect per IPC-A-610.

Question 4

When inspecting conformal coating under ultraviolet (UV) light, what does a dark or non-fluorescing area indicate?

Accepted Answer

Missing or insufficient coating coverage

Answer

Areas that do not fluoresce under UV light lack the fluorescent tracer present in the conformal coating, indicating that no coating or insufficient coating was applied in that location.

Question 5

During conformal coating application, which types of features MUST typically be masked to prevent coating?

Accepted Answer

Edge connectors, test points, and adjustable components

Answer

Edge connectors must remain uncoated for electrical contact, test points must remain accessible for in-circuit testing, and adjustable components such as potentiometers must remain operable after assembly.

(CIS) Certified IPC Specialist Practice Test

(CIS) Certified IPC Specialist Practice Test

CIS Conformal Coating & Encapsulation 2