MEMS-Based Multilayer Piezoelectric Ceramic Actuator Characterization System Developed with NI LabVIEW and NI SCXI Hardware

Author(s):
Quintin Stotts - Data Science Automation

Industry:
Industrial Controls/ Devices/ Systems

Products:
Switches, LabVIEW

The Challenge:
Increasing throughput for MEMS-based piezoelectric ceramics test systems to meet increasing customer demand.

The Solution:
Using virtual instrumentation to create a high-performance automated test system capable of testing up to 20 devices at a time.

Multilayer piezoelectric actuators accurately generate micron-level movements. These complex devices are the enabling technology in research and commercial systems such as inkjet and laser printers, ultrasonic cleaners, and high-resolution video projection systems. While using multiple layers of thinner ceramics reduces the power requirements, it also tightens the manufacturing constraints; this makes the resulting devices more universally usable, but it also renders the accuracy of production testing much more critical.

Data Science Automation (DSA), the industry-leading supplier of piezoelectric ceramics based on MEMS (microelectromechanical systems), needed to increase our test system’s throughput due to the increasing demand for these devices. To achieve this increase in throughput, we needed to make the process faster and expand the number of devices under test (DUTs) per test cycle. These improvements required an intimate knowledge of the physics of the DUTs in order to select the most appropriate hardware and develop a high-performance software solution. The new system would need to give pass/fail indication of the different tests being conducted, store the test data into an organized file structure, and display historical statistics of the test results.

The solution was to create a scalable, high-performance automated test system that provides batch testing of 20 devices, real-time updates of individual device measurements as well as pass/fail indications, and a flexible method to adjust the tolerance limits for the tests.

We were tasked with developing software to automate the ceramic device test procedure in order to meet the demanding throughput requirements, and with selecting hardware, which needed to augment the client’s legacy test system. We used National Instruments LabVIEW to develop the application, which is able to conduct tests in approximately 5 percent of time the previous manual test process took due to NI switching hardware and the easy-to-use NI switch VI library. The new user interface displays which tests passed with an LED, and also displays the corresponding measurement value. The front panel also contains configuration settings and statistics of a device’s test history.

The National Instruments hardware we used in this application was a key component of the system’s successful development and implementation. The NI SCXI-1000 chassis was extremely easy to interface to the PC using the NI USB-1359 SCXI plug-and-play communication adapter kit. The ability to expand the matrix of the NISCXI-1127 switch using expansion cables also made setting up the text fixture much simpler. The software switches through the 20 DUTs, taking capacitance and dissipation measurements, comparing them to established limits, and updating the user interface with measurement values and pass/fail results. The system then charges all 20 DUTs to a specified voltage and switches through them, again taking an insulation resistance measurement. If all three measurements are within the limits, then a larger LED indicates that the devices passed the acceptance test. The limits can also be saved to and read from an .INI file and organized by part number, along with the charge voltage values.

After a test run is completed, the acquired data is stored in four different test files. For each manufacturing lot, separate files accumulate the measurements for each of the three measurement types (capacitance, dissipation, and insulation resistance). A fourth file accumulates the overall summary results for batches of 20 DUTs from the results shown on the user interface. These test files can be read to display the last overall test pass/fail number, the total pass/fail number for each of the three tests as well as the overall test, and the total overall test pass/fail quantities based on each position in the test fixture. This allows characterization both of the DUTs and of the fixture to identify possible degradation of electrical contacts.

The solution exceeded the client’s expectations on its performance, ease of use, flexibility, and scalability over testing one device at a time by hand. All the operator has to do is click on a button and within minutes, the system tests 20 devices and displays and archives the results.

For more information, contact:

Quintin Stotts

Data Science Automation, Inc.

375 Valley Brook Road

McMurray, PA 15317

Tel: (724) 942-6330

Fax: (724) 942-8390

 

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