Nikkei Electronics Asia -- March 2009
Insights
Strategies for Maximizing Test System Efficiency

Mar 25, 2009 15:59 Nikkei Electronics Asia

Despite rapidly increasing device complexity, test engineers have to deliver higher-speed and lower-cost test systems and now must consider the requirements of their corporate sustainability programs. These corporate sustainability programs often have goals of reducing energy consumption, carbon footprints, and emissions.

Many manufacturing and engineering teams are now given sustainability targets with the goal of using resources more efficiently. Companies can meet the objective of increasing test system efficiency by applying the following three strategies: reducing test times by maximizing instrument utilization; increasing instrument longevity with reuse; and using more energy efficient instrumentation.

Maximizing Instrument Utilization

Increasing the throughput of an automated test system delivers efficiency gains. By using commercial off-the-shelf (COTS) tools such as multicore processors, PCI Express, field-programmable gate arrays (FPGA), and NI's LabVIEW software, one can create parallel processing and parallel measurement systems capable of testing a single unit under test (UUT) with the shortest possible test time.

One technique for further maximizing efficiency is adopting a parallel test strategy on multiple UUTs. Parallel test clearly reduces aggregate test times and improves instrument utilization (Fig 1), but the complexity of developing a parallel test system can be prohibitive. Developing your own test management software that implements the testing of multiple UUTs at once requires a low-level understanding of parallel programming and multi-threading.

An alternative to developing a custom parallel test system from scratch is to use off-the-shelf test management software, such as NI TestStand. NI TestStand abstracts the low-level complexity of parallel test system development using built-in features for executing parallel test sequences in multiple threads and managing both the OS and instruments.

Increasing Instrument Longevity

By developing reusable systems, engineering teams can maximize instrument utilization while extending the life of their test systems. A reusable automated test system should be based on a flexible, modular hardware platform, such as PXI, in which you can reconfigure in software to test multiple product generations and even different types of products. An example of a company realizing the benefits of a modular, software-defined test architecture is Benchmark Electronics, which developed a standard test platform to maximize the reuse of existing assets to test a wide range of product categories. The reusable tester can accommodate a variety of board- and device-level parametric and stimulus-response tests. The standard instrumentation system includes a PXI chassis, an MXI controller, digital I/Os, a digital multimeter (DMM), a digitizer, and a function generator. Depending on the test requirements, there is ample room to add instruments for specific needs without disrupting the standard instrument suite because of the flexible software framework based on NI TestStand and LabVIEW. Efficiency gains can be realized by reusing test systems over the development of a wholly new test solution.

More Energy Efficient Instrument

A recent energy study revealed that the largest energy consumer in the US, the US federal government, could save more than US$1 billion in power costs over the next five years by switching to greener technologies. While the average electronics manufacturing facility may use more energy in other parts of the process, test still has to play its part in minimizing energy use. Evaluating the tools test engineers use shows that a large portion of energy consumption is due to the instrumentation used in a test system. Today, there are two major options for building automated test systems - PXI and rack-and-stack instrumentation. Analysis of a comparable mixed-signal system on each platform reveals that a PXI system consumes 60% less power than a rack-and-stack system (Fig 2).

The primary factor for the difference in power consumption is that all modular instruments in a PXI system share the same power supply, chassis, and controller. Rack-and-stack instruments, however, duplicate the power supply, chassis, and controller in every instrument, which dramatically increases their power consumption. Because of its reduction in power consumption, a PXI system can reduce the energy costs by more than US$2,000 over five years for each test system in one analysis. In a factory with 100 testers, this energy savings could be as much as US$85,000 per year.

Cost is not always the only reason for reducing energy consumption. In fact, many organizations receiving electricity from fossil fuels are also focusing on reducing their carbon footprints and emissions. The lower energy consumption PXI offers can actually have a larger impact by reducing carbon emissions. Every PXI system that displaces a rack-and-stack system reduces carbon emissions by 5,925lb per year, which is nearly half the amount of carbon emitted by an automobile each year (the average American car emits 12,100lb per year).

Manufacturing test has an evolving role to play in helping manufacturers reduce their impact on the environment by increasing throughput, maximizing reuse, and minimizing test system energy consumption. Test system performance gains do not come at the expense of sustainability; in fact, they help drive it.

by Jayaram Pillai, Managing Director for IndRA (India, Russia & Arabia), National Instruments

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