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QML - The Best of Both Worlds

Visible evidence of a world defense in transition is all around us. In recent years, changes once thought unlikely became reality. Borders fell, political systems were restructured, and alliances once considered impossible are now the norm. While the major news events garnered most of the world's attention, it may be the less publicized changes that define the defense industry in the next century.

In the United States, defense acquisition reform is one topic that received a great deal of attention in the last several years. All of the speculation resulted in action in 1994 when Secretary of Defense, Dr. William Perry, authored a mandate that, in effect, called for the Department of Defense to utilize performance standards to purchase components for use in end systems. To ensure the mandate is adhered to, any contractor involved in a new design or system upgrade must obtain a waiver to use MIL-Spec product in a system. This is a complete reversal to the policy in existence prior to the Perry mandate.

The mandate was a decisive action aimed at moving the defense procurement process away from the strict, regimented "mil-spec" system that, in many cases, added unnecessary costs to defense contracts. At the same time, the DoD sought to implement "Best Commercial Practices" and to utilize many of the advantages found in the commercial world.

One potential limitation of the DoD action was its broad-brush approach covering everything purchased by the DoD and its contractors, from boots to integrated circuits. For commodity items like clothing, it isn't difficult to see the logic in a less rigid, less costly commercial equivalent. However, highly complex integrated circuits are a different matter.

Although the military semiconductor industry did not foresee the DoD's action, its members recognized early the need for changes in military ICs manufacturing and procurement. More importantly, they recognized that their customers' needs were changing. As a result, key industry members began working proactively in the mid-1980s to develop a methodology that preserved the high-quality, high-reliability ICs the armed services had come to expect while also incorporating the most advanced commercial qualification and procurement methods. The result was a comprehensive process methodology named the Qualified Manufacturers List (QML).

QML Joins Best of Military and Commercial Worlds

The DoD originally listed the Qualified Manufacturers List as an ordinary military standard. It was a mil spec for classification purposes, but for practical purposes it was anything but a mil spec. The government formally recognized this in early 1995 and gave QML the status of MIL-PRF-38535. This means that QML officially went beyond mil-spec status to meet the definition of a "performance- based specification" as called for in Dr. Perry's earlier mandate. For both IC manufacturers and defense contractors, the decision went a long way in providing an IC standard that offers the best of both the military and commercial worlds.

The benefits of QML are many, but they are best understood when comprehended against the system QML replaced.

Screening Quality In

From the inception of the IC by Texas Instruments Jack Kilby in 1958, quality and reliability remain primary manufacturing objectives. TI designed the first integrated circuits for use in military systems, and these ICs had to perform to the rigid standards prescribed by the US government. As a result, a testing and reliability environment grew up around the industry ensuring the parts designated for military use would perform to expectations in a wide range of extreme conditions.

The result of this early work was a broad system named the Qualified Parts List (QPL) system. Administered under the armed services supply center, DESC, QPL's charter was to guarantee the ICs purchased by military contractors met the U.S. Government's strict standards.

The process evolving under the QPL system became known as JAN and is described under the DSCC standard MIL-M-38510 and additionally under MIL-STD-883, Paragraph 1.2.1 in which the Joint Army-Navy (JAN) look-alike parts were built. The main benefit of MIL-M-38510 in the early days, and ironically, its biggest drawback today, is the fact it attempts to "screen" quality in through a rigid set of tests that manufactures complete for each and every device lot.

Regardless of device type or maturity, the manufacturers perform the same tests for every lot in spite of manufacturers' data showing parts of the qualification process might be dropped without affecting the device's reliability.

While the QPL system remained inflexible for decades, the semiconductor industry did not. The industry continued to improve quality and reliability through process manufacturing techniques like Statistical Process Control (SPC). Instead of trying to screen out defective products after they have been manufactured, QML ensures quality and reliability in the manufacturing process.

QML Means Best Commercial Practices

For early IC manufacturing, the QPL system worked well, but it did not incorporate the many advances in process technology the IC industry achieved over the years. QML, on the other hand, was designed to incorporate these best commercial practices into its comprehensive methodology. The fundamental difference between the two systems is that QPL is a strictly prescribed guideline for achieving quality. In contrast, the QML process is flexible and allows the manufacturer to do the thing he does best -- continuously improve the process for manufacturing a quality product.

For the manufacturer, and ultimately the consumer, the most important benefit of QML is it allows the elimination of non-value-added steps. The older QPL specification mandated each and every device coming off of an IC assembly line must be subjected to the same rigorous quality checks, despite years of data indicating parts of the screening process were unnecessary. The QML process allows the advantage of analyzing data gathered from the manufacturing and testing process. When the manufacturer has sufficient data to prove a particular step is no longer necessary, he can delete it.

Centrifuge, 100X inspection, temperature cycle and burn-in are examples of eliminated process steps on TI's older technology devices made possible through QML. As manufacturers accumulate additional data, more flow deletions are possible.

QML Manufacturing and Assembly

Another advantage of QML is it qualifies the entire product family via certification of the process flow. Once an IC company's process has been certified or listed as QML, the manufacturer must continually meet or improve on the established baseline under which it qualified.

The DoD has announced the approval of self-certified, off-shore wafer fabs under MIL-PRF-38535. Under the QPL system, all wafer fabs sourcing QPL ICs were required to be located in the United States. This effectively limited the number and types of devices available to military customers. With QML, customers have more total system solutions from which to choose.

Customer Benefits Under QML

From a production perspective, QML customer benefits include the manufacturer's ability to convert rapidly to new technologies. Reduced screening means reduced cycle times, and since QML allows elimination of non-value-added manufacturing steps, QML has the potential for cost containment. In addition to rapid product introduction, reduced cycle time and potential cost savings, QML devices do not suffer from the defects sometimes induced by an extensive screening process. Rigorous screening does not improve the quality of the part. In some cases, it may even hinder device quality.

QML Retains Best of Military World

While QML incorporates many of the benefits found in the commercial IC manufacture, qualification and procurement world, it also retains the best features traditionally found in the military IC world. Retained are the types of special services military customers have come to expect as vital to the specialized design and procurement environment in which they work. Configuration control, device traceability, standardized supplier certification and obsolescence control are just some QPL attributes maintained under QML.

DoD and IC Industry Accept QML

Early on, DSCC recognized that QML provided not only a screen for quality products but one for quality organizations as well. As a result, DSCC considers QML product equal to or better than QPL products. Jim Blanton of DSCC explains. "The QML approach is basically a validation that a company is well managed and technically sound enough to be "World Class" with minimum government interference."

Long-term suppliers in the IC industry accept QML as the methodology of choice. To date, there are currently 27 QML suppliers in the industry. The significance for customers is the assurance of a long-term and multiple-source supply for their military systems.

TI and QML

QML was given life through the government's support of TQM (Total Quality Management) programs in the 1980's. TQM, initially designed for application to any manufacturing system, is especially ideal for the precision techniques found in IC manufacturing. Texas Instruments has long been a supporter of TQM principles and recognized early on the need for performance-based specifications for military IC manufacturing. As a result, TI was a pioneer in the development of the QML performance-based specification.

Today, Texas Instruments HiRel Defense & Aerospace is the largest supplier of QML products with over 3,500 device types. And as part of its ongoing pledge to serve its military and aerospace customers, TI continues to release new standard and differentiated products qualified to QML specifications. From new advanced system logic and mixed-signal functions to highly integrated DSP multichip modules, TI provides the tools you need to compete in today's changing military market.

QML Q & A

What does QML mean?
Qualified Manufacturers List
Is QML a military specification?
No. QML is a performance base specification, MIL-PRF-38535.
Where do DSCC SMDs, JAN and SNJs fit under the QML umbrella?
The SMD, JAN and SNJ specifications now define the electrical performance specification for the particular device. These devices may now be built using the QML (MIL-PRF-38535) as the process performance specification.
What is Best Commercial Practices and how does that relate to QML?
Best Commercial Practices is a term applicable to any business product, process or system. It implies the elimination of non-value added steps.
QML allows a supplier with significant statistical data, to eliminate process steps which do not add value to a process flow.
How can I tell if the processing of a device has changed under QML?
All TI Military devices, with the exception of mil-temp (SN/SM) and plastic, are shipped with a Process Conformance Report that shows what processing the devices received.
How does TI decide what process steps should get eliminated from a device flow?
TI first collects significant statistical data proving a given process step is not adding value to a device flow. With the agreement of the Technology Review Board (TRB), the process step can then be eliminated. ex. 216,670 HC/HCT devices were tested at -55 with zero test related failures. -55 is no longer performed on HC/HCT devices.

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