Developing a Versatile Test System to Reduce Semiconductor Cost of Test


"Using PXI hardware and TestStand is an easy and versatile solution that maximizes the test fixtures and extends their operating life."


The Challenge:

Identifying a cost effective solution for performing fixture test and repair in line with manufacturing flow that requires minimum overhead and does not affect ATE productivity.

The Solution:

Using PXI hardware and TestStand software to develop FlexyTest, which is an easy and versatile solution that maximizes the test fixtures and extends their operating life without affecting the ATE productivity.


Massimiliano Giancarlini - SYNERGIE CAD INSTRUMENTS


The semiconductor Cost of Test (CoT) depends on the Overall Equipment Efficiency (OEE), which takes into account both the automated test equipment (ATE) uptime and the availability of test fixtures (test boards and interfaces).


We perform ATE maintenance with dedicated tools (diagnostic and calibration tools), so that other manufacturing equipment is not impacted. We perform fixture maintenance using ATE systems (different ATE systems to cover the related fixture standards) with dedicated test programs. This approach requires the availability of machines normally used for testing semiconductor devices during the manufacturing process and engineering resources with dedicated skills on specific ATE platforms for test program development.



We developed FlexyTest, which is a universal platform that can verify and diagnose text fixtures developed on different ATE standards on a single machine. Thus, we can fully exploit production testers to maximize the overall IC productivity.


Moreover, we designed FlexyTest as a diagnosis and repair station, so it can optimize the maintenance process and provide these benefits:

• Possibility to efficiently schedule fixture maintenance since, unlike the ATE, its availability is not dependent on the engineering and manufacturing activities of the production plant
• Minimum cycle time for test execution since no parts must be removed from the fixture to be tested (fixture tested as on the ATE)
• Possibility to perform in-line repair while running diagnosis, using the real-time troubleshooting functionalities
• Universal easy programming interface to develop test programs for different fixture families (no need to develop programs on different ATE development environments)


FlexyTest can quickly switch across different fixture standards through a set of application kits covering the NI Semiconductor Test System (STS) and other ATE platforms. Each application kit includes:

• Fixture Adapter (FA) - Mechanical and electrical interface between fixture under test and system
• Close Loop Adapter (CLA) - Interface closing the electrical loop between the fixture circuitry and the machine, thus enabling the parametric test
• Test recipe template  - Customizable framework for the development of test recipes for all fixtures of the same typology (same ATE standard)


Custom application kits can be released for specific machines.

We based FlexyTest on the TestStand architecture and equipped it with a software user interface for smart test recipe development (engineering mode) and test execution (operator mode). The user interface, designed and developed with LabVIEW, uses the TestStand APIs to define, execute, and log every single step defined by the user.


Test recipes, describing connections and components on the board under test, can be developed starting from PDF schematics or by automatically importing board design files. This helps save over 50 percent of time with respect to standard development on ATE platforms.


We use FlexyTest to perform parametric tests on the fixtures, so we can immediately identify the actual root cause of the failures. We also take advantage of real-time monitoring during test execution, with information on critical nets and component issues, to quickly identify root causes. We designed the software to support in-line troubleshooting and debug, with the possibility of interrupting and repeating test sequences for fast diagnosis, repair, and validation.


The modular and scaleable hardware configuration provides a smooth system evolution in line with NI roadmaps and the customer’s needs in terms of capability and performance. The following modules represent the core of the FlexyTest system:

• PXI-4130 power source measure unit for sink/source in four V/I quadrants, with 4-wire remote sensing capability
• PXI-4072 digital multimeter with LCR for measurement of voltage, current, inductance, resistance, and capacitance values
• PXI-6541 high-speed digital I/O for matrix module control and main functionality test


We designed the basic system configuration to cover all the standard parametric tests required to certify the functionalities of the fixtures implemented for the most common ATE platforms. In case a higher quantity of system resources or specific types of measurements are required, we can easily expand FlexyTest with additional modules.


Standard test libraries cover the most common circuits and components, including:

• Resistance measurement
• Capacitance measurement
• Inductance presence
• Relay functionality
• Buffer functionality
• Op amp offset and gain
• Multiplexer functionality


We can easily develop new objects using LabVIEW or C to match specific hardware structures, optimize fixture test sequences, and add new components to the library. Test results are available in XML format or customized reports, according to specific requests. SDTF reports are available, which takes advantage of all the data processing from this file and can handle fixture test results with the most common tools used for the IC test data analysis.



FlexyTest represents a cost effective universal solution to perform test fixture maintenance boosting the IC manufacturing efficiency. Users can save over 70 percent of fixture maintenance costs, with respect to the present workflow based on ATE, and guarantee investment payback in less than one year.


Author Information:

Roger Cagliesi

Figure 1: Architecture of FlexyTest system
Figure 2: FlexyTest Workflow
Figure 3: User Interface for Test Recipe Development