Mil-PRF-38535 - Page 1 of 3: Intro to QML and TRB

LINKS:

The Mil-PRF-38535 Standard

The Mil-PRF-38535 is a performance-based specification document that defines the general requirements, as well as the quality assurance and reliability requirements, for the manufacture of microelectronic or integrated circuits intended for use in military applications and related government microcircuit application programs.

Unlike the rigid military standards of the past, however, the Mil-PRF-38535 is designed to provide microcircuit manufacturers with maximum flexibility to employ the industry's best commercial manufacturing practices while still achieving the government's required quality and reliability levels. To be granted such privilege, a manufacturer must first be certified to what is known as the Qualified Manufacturer Listing (QML), by complying with certain requirements of the Mil-PRF-38535. Developed in 1995, the QML program aims to move the defense procurement process away from its erstwhile strict, regimented specifications to a newer system based on best commercial practices.

A non-QML-certified manufacturer must adhere to the stringent and non-flexible requirements of the military for the manufacture and repetitive testing of its military products. Once a manufacturer is granted QML status, however, it is allowed to use best-known commercial practices to manufacture its products using its own process flows, as long as these are shown by data to produce products that meet military standards. Thus, a QML-certified manufacturer is free to pursue continuous improvements on its own, usually in the form of elimination of non-value-added process steps.

The first requirement of Mil-PRF-38535 is for the manufacturer to have a quality management (QM) program that is documented in its QM plan. The manufacturer must subject its QM program to self-assessments, results of which shall be made available for review.

The manufacturer must also form a Technical Review Board (TRB), which shall be responsible for the following: 1) development of the QM plan; 2) control of process changes, which includes qualification and certification of all processes; 3) analysis of reliability data; 4) failure analysis functions; 5) implementation of corrective action and recall procedures; etc.

The TRB shall maintain records of all its deliberations and decisions, which shall be made available for review. The TRB shall ensure that the QM plan includes the following: 1) quality improvement plan; 2) failure analysis program; 3) statistical process control (SPC) plan; 4) corrective action plan; 5) change control program; 6) standard evaluation circuit (SEC) and technology characterization vehicle (TCV) program; and 7) certification and qualification plan.

The Mil-PRF-38535 also defines requirements for change control procedures. All changes to any part of a QML manufacturer's line are to be governed by the manufacturer's TRB. Any change shall be documented as to the reason for the change with relevant data taken to support the change, including reliability data as appropriate. The criticality of the change shall be based on the effects of the change on quality, reliability, performance, and interchangeability of the resulting microcircuits. The next page shows examples of manufacturing process changes that require TRB evaluation and approval per Mil-PRF-38535.

HOME