Nadcap® Specifications for Conformal Coatings

The National Aerospace and Defense Contractors Accreditation Program

The National Aerospace and Defense Contractors Accreditation Program (Nadcap^®) provides cooperative global accreditation covering all aspects of product manufacture in the aerospace, defense and engineering industrial sectors, as well as for related industries. Product and process conformity assessment is the key to Nadcap’s industry-managed accreditation criteria, generating standards derived from compliance to workmanship-focused checklists for component manufacture; adherence to prescribed standards also relies upon the consistency of blind processes.

Need for Nadcap

Established in 1990, Nadcap is administered by the Performance Review Institute (PRI), located in Warrendale, Pennsylvania, with additional offices in Europe (England) and Asia (China, Japan). From the beginning, the Institute’s objective has been to develop and maintain reliable, standardized approaches to quality assurance (QA) in the industries it serves, stemming from stringent industry consensus standards that satisfy the requirements of all participants.

Prior to Nadcap’s creation, aerospace, defense and related firms verified process-compliance through audits of their own suppliers. Often extreme similarity resulted from their own process analyses for verifying compliance, because these processes paralleled those provided by the suppliers. The consequent redundancy of process assessments created a high incidence of comparable audit results. Despite greater cost in money and time conducting audits, little value was added for firms within these industries. PRI’s administration of the Nadcap program has eliminated many of these conditions, generating greater levels of QA and overall product/process consistency for aerospace and other industries.

Nadcap Standards

Consistent Nadcap standards are developed from contributions by industry-specific, technical experts selected from both government and industry sources. These personnel devise and monitor accreditation requirements, defining operational program standards. Nadcap accreditation is an industry-driven program.

In the case of the aeronautics, the industry-directed program is the outcome of participation from highly qualified individuals with sufficient experience in the aerospace industry to conduct the actual process audits, using criteria specific to each designated manufacturing process; audits are enacted at the company level. In addition to company-level accreditation for such industrial/manufacturing procedures as chemical processing, conventional machining, heat-treating, product testing and welding, Nadcap offers standards for coatings (CT).

Nadcap for Conformal Coating

The role of conformal coatings as protective insulators of circuit card assemblies is well known. One Nadcap standard particularly relevant to conformal coating is the AC7120.

AC7120 Rev A – Nadcap Audit Criteria for Circuit Card Assemblies: This Nadcap standard provides a set of test guidelines and performance criteria for conformal coating use in PCAs and other circuit card conditions. Most pertinent is Section 14, Coating and Encapsulation, which specifically covers auditing standards for conformal coating. Unfortunately, most conformal coating applicators do not build or assemble CCA’s, making them ineligible to receive this certification. However, as long as the end customer who is certifying the end product is Nadcap certified, we have had no issues with our customers claiming the conformal coating is indeed Nadcap approved.

Summary

Nadcap is the leading worldwide cooperative program encompassing the participation of major companies; it is designed to manage a cost-effective consensus approach to industry-specific manufacturing processes and products.

In this context, Nadcap oversight generates industry-standard manufacturing and testing specifications, designed to stimulate ongoing QA and product improvement within the aerospace industry. Standard AC7109 provides audit criteria for conformal coatings. AC7109/2, covering Audit Criteria for Vapor Deposited Coatings Physical Vapor Deposition (PVD) and Chemical Vapor Deposition (CVD) processes, such as those used with Parylene, is particularly pertinent, but the entire Standard has considerable importance for aerospace assemblies. AC7120 Rev A – Nadcap Audit Criteria for Circuit Card Assemblies – is also relevant to providing company-level accreditation based on specific processes used by aerospace suppliers.