10.4. Pre-Cure Examination. Immediately after material application, the uncured conformal coating shall be examined for: a. Bubbles and Air Entrapments. These defects shall be broken by vacuum, with a sharp probe, or other appropriate tools. b. Bridging. Conformal coating material shall not be allowed to bridge between the bottom of ceramic-bodied DIP's or surface mounted parts and the PWB, or between the part lead and the PWB, thereby negating stress relief. 10.5. Post Cure Examination. After the cure cycle, the conformally coated PWB or PWA shall be examined to assure that the following conditions are met. See Figure 10-2 through Figure 10-5 for additional requirements. a. Conformal coating is uniform in color, thickness, and texture, tack-free, and shows proper adhesion to all coated surfaces. b. Conformal coating shall cover all areas as specified on the engineering documentation, have a smooth continuous surface, and follow the contours of the PWA. Minor pull back from sharp points and edges is permissible unless otherwise specified on engineering documentation. c. Conformal coating is free from contamination. d. Terminals shall be conformal coating encapsulated, including the insulation gap of the wire, unless it is a solder ball type connection (as in a high voltage connection). This is normally applied with a brush after the initial conformal coating application. e. Conformal coating may bridge between adjacent part leads providing stress reliefs are not negated. f. Conformal coating shall not exhibit discoloration (due to such things as excessive curing oven temperature, contamination, etc.) [Workmanship Standard for Staking and Conformal Coating of Printed Wiring Boards and Electronic Assemblies, NASA-STD-8739.1, August 6, 1999]
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