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Publication Date: 08/1/2009
Archive >  August 2009 Issue >  Special Features: Test and Measurement > 

Integrated MEMS Test Cells for High-Throughput
All-in-one cell for complete MEMS testing.

Integrated test cells, specifically designed for testing MEMS devices, represent a substantial innovation today. These ready-to-use cells are able to support the market for MEMS components, whose demand is expanding geometrically — driven by consumer and automotive applications.

ATE producer SPEA, responding to increasingly strident demands from manufacturers, has developed automated test cells designed specifically for MEMS devices. The test cells integrate all of the elements for handling, contacting and complete testing, including physical stimulus for functional test and tri-temp thermal conditioning.

An unusual aspect of these test cells is that all the components are designed and manufactured directly by SPEA for this integrated operation. This design process guarantees cost optimization, since the whole system is conceived, produced and supported by just one manufacturer. The result: the company that has to test MEMS devices does not have to worry about the choice of individual system components for the test, handling, physical stimulus, and then about the process of integrating them. The test cell works as a single unit that is able to perform all the operations for the test and handling of MEMS devices. This includes the latest generation of components that integrate multiple sensor functions on a single chip.

Integrated vs. Hybrid
Most test system manufacturers normally assemble, in a "test cell", parts purchased on the market. SPEA's solution is different; it produces the only "integrated" test cells, while other products, sold as "test cells", are in reality "hybrid" solutions.

The main advantages are noticeable immediately at the economic level, with lower investment and cost of ownership. At the technical level, the integrated cells provide the best possible performance as well as optimized operation at production level, with greatly improved throughput.

"There are MEMS producers who have dealt with their test needs by purchasing hardware from a variety of manufacturers, then integrating these components themselves. This is not only immensely inconvenient, but imposes serious limitations on the test station's capabilities. In addition, sources for the fact that none of the producers of the individual components do not have the background, capability or willingness to be responsible for the entire test setup," explains Luciano Bonaria, president and CEO of SPEA. "By having all the elements coming from the same manufacturer, the user can establish a clearly defined accountability for the entire test cell. This relieves the user of having to deal with possible technical issues."

The integrated test cell performs the complete testing — both parametric and functional — of the fully packaged device, providing huge benefits when compared to the strip test. The component tested in its final package is at the end of the production process; after the test, the device can be shipped to the customer, since it will not need anything further.

On the other hand, components tested in non-integrated procedures need to be singulated, which requires a re-test to verify that no damage occurred to the delicate mechanical parts of the MEMS being tested.

Luciano Bonaria goes on to explain SPEA's strategic choice of investing in MEMS test, highlighting the advantages that have brought the success of the proposed solutions:

Why did SPEA invest so significantly in MEMS? According to Mr. Bonaria, "The role that MEMS play in our lives is increasingly important, as they are finding their way into more and more products. And MEMS are playing an increasingly important role in the semiconductor industry."

MEMS producers quickly came to the realization that testing MEMS is not the same as testing CMOS components. Since the device is comprised of both electrical and mechanical parts, including three-dimensional structures, the test function has the additional burden of all these complexities. Not many companies have the knowledge and experience to be able to provide complete and convenient-to-use test solutions.

"With the increased demands on MEMS, the solutions that worked before are no longer adequate, especially for the high volume production needed for the consumer electronics and automotive electronics markets. MEMS producers require test cells with greater capability, ease-of-use, and in a reduced footprint," Bonaria explains. "This is why we created the integrated test cells — systems that clearly provide the only possible solution to meet the production needs of this high-growth market."

This innovative, all-in-one approach provides several immediate advantages. These include:

  • Reduced costs, when compared with any solution based on components from several different manufacturers.
    • Short application development time and ease of refining tests for new devices.
    • Improved ease of use and maintenance, which immediately reduces the cost of ownership.
    • Scalability and easy modification as well as extension of the equipment to answer new requirements. This is due to the single scalable and modular architecture, together with the convenience of having a single company with intimate knowledge of the whole system.
    • Configurability and rapid accommodation of different applications. It is highly unlikely that other solutions, designed to test one package and sensor type only (such as accelerometers) can be readily changed over for other tests. The SPEA tool allows for quick setup changes (less than 5 minutes) to adapt the machine to different and multiple sensor stimulus modules, and different packages.
    • Very high throughput, due to the full automation and the high parallelism in handling and testing. The system also works for functional test, which further reduces the cost of testing.

    Inside the Test Cell
    A typical MEMS test cell integrates the following elements:

    • High-throughput pick-and-place test handler (12,500 UPH), specifically designed to perform gentle, fully automated tray-to-tray or tray-to-reel handling of MEMS devices, without applying extra force to the component; The components are picked up from trays, transferred to a test area set up for the product under test and, at the end of the test, they can be placed on trays or reel.
    • High-performance test system for parametric and functional testing of MEMS, based on the technology and experience gained in the test of systems-on-a-chip. The test cell systems provide high performance and measurement capabilities, accuracy and reliability.
    • Stimulus units that apply all the physical stimuli required for functional test — acceleration, angular stimuli, vibration, acoustic stimuli, pressure, magnetic field — while properly protecting devices from unwanted environmental influences.
    • Thermal conditioning, through an innovative nitrogen-less, chamber-less system, when the component needs to be tested at tri-temp (cold/ambient/hot).
    • Socket units and loadboards designed for positioning and contacting the devices without applying force that would affect their mechanical behavior.
    • Operating system and test program, providing a unique software environment for test cell management and automatic source code generation for the test program.
    • Complete service and support provided directly by the company.

    Bonaria concludes by summarizing the benefits resulting from the use of the test cell solution: "The users of the integrated test cells can take advantage of SPEA's expertise, systems performance, complete support and ready availability. We employ a dedicated team of high-level engineers with unequaled experience in MEMS testing. The MEMS market is ready for exponential growth, and it will surely benefit from the availability of test solutions specifically designed for these devices, ready-to-use and able to drastically reduce the cost of test."

    Contact: SPEA America, 2609 S SW Loop 323, Tyler, TX 75701 903-595-4433 fax: 903-595-5003 E-mail: Web:

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