Junifer B.. Frenila - Analog Devices, Inc., Philippines
Perryl Glo G.. Supsup - Analog Devices, Inc., Philippines
An application board is a printed circuit board containing various complementary ADI products to market one anchor device, as seen in Figure 1. Application boards have standard connectors and ports, making it easy for customers to interface them with different systems, giving customers the edge to accelerate prototyping and early product release.
To ensure application board quality, we manually test each board’s functionality. This type of test requires many resources and is very time consuming. On the other hand, with automated testing, we can repeat saved programs, compare results, and log data in a very short time. Because of this, an automated generic PXI-based application board tester is an essential component in ensuring application board efficiency and effectiveness.
To make the tester generic, we used an interface called an interposer board with a bed of nails (BON) on top of it, as shown in Figures 2a and 2c. It is designed so that each and every unique application board can be mounted and tested. The BON is unique for each product because each product has a different application board. It is also planned with fittings to hold the board in place for testing. Users must identify application board test points with which the BON must be in contact, as shown in Figure 2b.
The interposer board interfaces the application board to the tester resources. Such resources are provided by the PXI modules (power, meter, or I/O). In this project, the chassis has 18 slots with a built-in controller. Cables and connectors are used as an electrical connection routing between tester resources and the interposer board.
The complete generic PXI-based application board tester is shown in Figure 3. On the bottom is the 18-slot chassis, followed by the built-in controller and various modules necessary for testing the application board. On top of the chassis is the interposer board, which handles tester resource breakout. On the very top is the BON with the actual board in place. Once the correct program is loaded onto the tester, the operator only needs to insert the board and initiate the testing process. This repeats until all boards on a single product are tested.
Figure 4 shows the software front panel developed for carrier device application board testing. The user interface consists of the program information box, where the operator keys in the necessary information; the button with which to initiate testing or start the retest; and the stop button. There is also an engineering mode button, which displays measurement indicators in the engineering tab for debugging; and lastly, the production tab (which shows by default) with which the operator can determine pass or fail results. The number of parameters to be tested is dependent on the specific device. Binning is determined in relation to pass or fail modes (for example, bin 1 for passed and bin 9 for continuity failure). The number of pass or fail parameters also displays.
The block diagram is not shown due to its large image size. The producer/consumer design pattern creates the virtual instrument (VI). More than 40 parameters are tested for this carrier device, and each of the parameters has its own subVI called by the text ring menu in predetermined order to optimize test time.
Figure 5 shows the simplified generic PXI-based application board tester method. Upon start-up, a PXI-4110 power supply provides power to the boards and its components. After the power sequence, a USB-6501 and PXI- 6556, using LabVIEW, generate the patterns that load onto the device. With every pattern, a PXI-4065 makes a corresponding measurement. Pattern-loading and output-measuring loop until all patterns have run. Measured outputs are compared to their limits and binned accordingly. Lastly, the results are logged and saved as a .txt file.
The system saves the data in text format, as shown in Figure 6. It can be translated manually as an Excel file for a more organized view. The data log contains information about the board under test, the operator working on the tester, and the list of parameters tested. Parameter names are found on the first column, followed by the lower limit, the typical specification, and the upper limit. The fifth column shows the measured value, its corresponding unit, and the bin assignment.
Using NI hardware and software offers the following advantages:
- Tester hardware is flexible and easy to assemble
- Software is faster to develop and easy to debug
- We can reuse subVIs in other device programs for much faster development
- There is lower power consumption compared to benchtop equipment counterparts
- It minimizes costs stemming from manual errors and inefficiency