Understanding MIL-PRF-31032, Part 1

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Overview

Unlike other specifications like the aerospace AS9100 standard that focuses on the quality management system, MIL-PRF-31032 is a performance specification; in other words, it was established to test PCBs to certify that they meet the necessary requirements for military use. The title of the specification is "Printed Circuit Board/Printed Wiring Board, General Specification For,” and the scope “establishes the general performance requirements for printed circuit boards or printed wiring boards and the verification requirements for ensuring that these items meet the applicable performance requirements.”

Unlike other certifications, like ISO 9001, where a company could still build commercial PCBs without the certification, there are no exceptions with the military. Every single PCB produced for the military/DoD must be manufactured by a company certified to the specification.

Companies that have been in the military game as long as ASC began certifying to the MIL-P-55110 specification, which was renumbered to MIL-PRF-55110 in 1997. MIL-PRF-55110 was the predecessor to MIL-PRF-31032 and is still in play for legacy military products. While a company can no longer qualify to 55110, they can continue to build and certify PCBs on legacy programs that still require this specification. As the military moves quite slow when it comes to change, there is still plenty of business to which this applies.

DLA

The Defense Logistics Agency (DLA) for Land and Maritime is the qualifying activity (the organizational element of the government that grants certifications) and will determine an organization's adequacy and compliance to the requirements listed in this standard. This determination involves verification of the implemented quality management (QM) plan by a Technical Review Board, validation of the effectiveness of the implementation of the QM plan, and demonstrated capability to produce a printed board technology. While the U.S. military sector of the PCB industry is relatively small, it is strategically important to the country and the world. Ensuring a reliable supply of such boards is the task of the DLA located in Columbus, Ohio. The main DLA tools for verifying capable supply bases are the military specifications for printed wiring boards. There are three main specifications: MIL-PRF-31032 (all boards), MIL-PRF-55110 (rigid PCBs), and MIL-PRF-50884 (flexible PCBs).

The DLA Sourcing and Qualification mission statement reads as follows: “The specific mission of the DLA Land and Maritime, Sourcing and Qualifications Division is to establish and maintain a known-good supplier base that has successfully demonstrated their products met the specified performance, quality, and reliability levels via the DoD Product Qualification Program.”

The DLA could be both your new best friend and your worst nightmare if you pursue and maintain MIL-PRF-31032 certification. The DLA could be your worst nightmare because they are extremely tough and thorough evaluators of your manufacturing process. Meanwhile, the DLA could be your new best friend because they will make you better. These folks know boards, understand the processes, and are absolute sticklers for a high level of performance from your PCBs.

QML

After successful completion of the qualification process, a company will then be listed on the qualified manufacturers list (QML)—a resource that identifies all of the certified companies, along with appendices that address various requirements/methods grouped by technology and specific end-use. This list is frequently used by military OEMs and contractors to select companies awarding new military/DoD business.

Future Articles

Over the course of this series, I will discuss topics such as MIL-PRF-31032 requirements, the quality plan, responsibilities of the Technical Review Board (TRB), and the testing and reporting requirements for the certified shop into the DLA.

Anaya Vardya is president and CEO of American Standard Circuits. Vardya is also co-author of The Printed Circuit Designer’s Guide to… Fundamentals of RF/Microwave PCBs and Flex and Rigid-Flex Fundamentals. Visit I-007eBooks.com to download these and other free, educational titles.

 

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