NASA Conformal Coating Workmanship Standard

NASA-STD 8739.1 is the Workmanship Standard for Polymeric Application on Electronic Assemblies. The standard describes NASA’s technical requirements, procedures, and documenting requirements for staking, conformal coating, bonding and encapsulation of printed wiring boards and electronic assemblies. It contains requirements which establish the responsibility for documenting, fabrication and inspection procedures to be used for NASA work, including supplier innovations, special processes and changes in technology. NASA-STD 8739.1 was initially released in August of 1999 with improvements and minor changes to the standard in recent years.

The standard is important because it defines the processes and quality requirements needed for mission hardware and mission-critical ground support equipment. This is a certification needed for both operators and inspectors of electronic assemblies that will be used by NASA.

NASA-STD 8739.1 is very similar to IPC J-STD-001 when it pertains to the application and inspection of conformal coating. Coating thickness and acceptable tolerances in regards to bubbles and scratches in the coating are nearly identical to IPC J-STD-001, with the exception that the NASA standard places strong emphasis on prerequisite vision testing, which covers near vision, far vision, a color test and not negating the stress relief built into components (i.e. No coating bubbles or foreign debris is allowed to bridge between the underside of a component or its leads and the circuit card surface).