Analog Devices Reduces MEMS Test Costs with PXI and LabVIEW
"Using PXI and LabVIEW, we were able to test our
MEMS devices at a fraction of the cost, weight,
power consumption, and footprint of our previous
ATE system."
- Woody Beckford, Analog Devices Inc. (http://www.analog.com/en/index.html)
The Challenge:
Developing an efficient, cost-effective, and compact system for MEMS testing in characterization and production.
The Solution:
Using NI LabVIEW software with PXI modular instrumentation to create a MEMS test system that can be used in both characterization and
production testing and delivers 11X reduction in capital equipment costs, 15X reduction in footprint, 66X reduction in weight, and 16X reduction in
power consumption over the previous automated test equipment (ATE) used in production.
Author(s):
Woody Beckford - Analog Devices Inc. (http://www.analog.com/en/index.html)
Rob Whitehouse - Analog Devices Inc.
Dan Weinberg - Analog Devices Inc.
About Analog Devices Inc.
Analog Devices Inc. (ADI) provides analog, mixed-signal, and digital signal processing (DSP) integrated circuits (ICs) that convert, condition, or otherwise
process light, sound, temperature, motion, or pressure into electrical signals for use in electronic equipment. Our ICs are found almost everywhere,
including automobiles, cameras, televisions, cellular handsets, medical imaging devices, and industrial automation equipment.
Over the past two decades, our company has made a significant investment in microelectromechanical systems (MEMS) inertial sensing technology. As a
leading MEMS innovator and a pioneer in micromachine technology, we produced the industry’s first fully integrated iMEMS® (integrated Micro Electrical
Mechanical System) accelerometers and gyroscopes, helping electronic designers incorporate acceleration, tilt, shock, vibration, rotation, and multiple
degrees-of-freedom (DoF) motion into their designs. We offer a full range of inertial sensing solutions, including our award-winning iMEMS accelerometers
and gyroscopes, iSensor™ intelligent sensors, inertial measurement units (IMUs), and iMEMS digital microphones.
Requirements for a New MEMS Test System
MEMS testing poses a number of challenges for the production test process. We needed an ATE system that met the demands of our product test plan
with the lowest possible cost while ensuring product quality. For our needs, our traditional “big iron” ATE solution was far too costly, too highly featured,
and physically too large to efficiently meet our requirements of a dedicated MEMS tester. We needed an application-specific test system for our MEMS
products with a subset of the measurement capability of a big-iron ATE system.
NI PXI and LabVIEW Deliver a COTS Alternative
We began evaluating a number of options as an alternative to our traditional production ATE platform. We wanted to leverage as much commercial
off-the-shelf (COTS) technology as possible to reduce the overhead required for a custom test solution. We also needed a test platform that was flexible
enough to accommodate custom MEMS test requirements while not sacrificing instrumentation speed or performance.
The PXI (http://www.ni.com/pxi/) platform from National Instruments offered the test instrumentation capability we needed to meet our challenge. PXI is a
widely adopted, open standard that has existed for more than 10 years and been implemented across a variety of industries. PXI gives us a high level of
flexibility and modularity to develop a targeted MEMS test system, which is reconfigurable for various test needs. For multisite testing, we can duplicate
test resources by plugging in additional modules without changing any of our software, allowing us to scale our test equipment as needed based on our
throughput demands.
We also needed our software environment to be inherently easy to use with the ability to create operator, program, and data interfaces to existing tools to
ease the process of integrating a new ATE system into our production floor. We chose LabVIEW (http://www.ni.com/labview/) software, which was already
widely used in our characterization and design labs, to meet these challenges. We had considered using ANSI C or C++ for our test software, but after
performing a number of benchmarks with LabVIEW, we were impressed with its performance and ability to take advantage of multicore technology.
We developed our new production test solution solely with PXI and LabVIEW. We chose National Instruments as our ATE supplier for this project for their
support, product offering, and global footprint. NI offered the majority of the test equipment we needed from a single source. National Instruments local
field engineers and system engineering teams worldwide provided support for our development teams throughout this project. The flexibility of the PXI
system combined with the ease of use of LabVIEW made it possible for our engineers to quickly design and prototype our solution. Test times were
comparable or better with our new test system based on PXI and LabVIEW versus our previous production ATE test system. We felt confident in
deploying a PXI-based production test solution based on NI technology for our MEMS devices.
Major Benefits of Using NI COTS Technology
Our new system offers a dramatic reduction in capital equipment expenditures, footprint, weight, and power requirements for MEMS production test using
PXI and LabVIEW.
Cost Savings: Our previous ATE system cost more for its basic configuration than our new PXI system’s total all-inclusive cost. The PXI system also
takes up very little space. In fact, our entire system is now physically small enough to wheel around on a cart.
Reduced Footprint on Production Floor: Our new PXI-based ATE system truly offers a zero-footprint tester. The system is small enough that we can
physically move it around on a cart, saving valuable space on our production floor.
Smaller, Easier-to-Use System: The weight comparison between the two systems offers a major reduction in shipping cost. Now, if any problems arise,
we can simply switch out PXI instruments on-site using local spares, or even ship the entire test system back to our development labs from the production
line with very little overhead. The shipping container for the previous ATE system alone would cost as much as our entire new PXI test system.
Decreased Power Usage: We previously had to get our facilities department involved months in advance to modify power grids and cooling systems to
accommodate additional testers. Now, our new PXI system is capable of running off of a standard power plug with absolutely no modifications required.
Increased Test Quality: The new system improved the overall quality of our testing. Because we designed the tester, we can ensure that every tester we
ship to our branch facilities features the exact same hardware and runs the exact same programming and code sequences. Furthermore, with LabVIEW
controlling the system, our programmed test code is modular and reusable for future test programs or in our development labs.
Same Test System for Characterization and Production: The added flexibility and ease of use for test development has led to our teams using the
same system in other phases outside of production, including design, characterization, and metrology. We now can use the same ATE equipment in all
environments without incurring an impact on cost. This helps reduce our time to market and increase our product quality.
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Our new NI PXI-based MEMS tester delivered significant savings in cost, physical space, and energy use
over our previous ATE system.
Using PXI and LabVIEW, we were able to develop an application-specific MEMS test platform that could scale from production to lab characterization,
dramatically allowing us to reduce our total cost of MEMS testing.
Author Information:
Woody Beckford
Analog Devices Inc. (http://www.analog.com/en/index.html)
Tel: (781) 937-1314
woodrow.beckford@analog.com (mailto:woodrow.beckford@analog.com)
Figure 1. Using LabVIEW with our PXI instrumentation, we created a dual-site production test system to test two MEMS devices in parallel in less time than on our
previous ATE system.
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Figure 2. We developed and deployed our new MEMS test system entirely with PXI and LabVIEW.
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Figure 3. To maximize the size, weight, and cost benefits of using PXI and LabVIEW, we use the same test solution in the characterization lab and production line,
which also helps us avoid any correlation issues between development and production.
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Figure 4. We used source measure units, power supplies, dynamic signal analyzers, high-speed digital I/O, and timing and synchronization PXI instrumentation from
NI to build our MEMS test system.
Figure 5. Robert Whitehouse worked with a team of engineers to create a PXI-based MEMS microphone production test system, saving 10 times the capital
equipment cost of the previous ATE system.
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