Test methodologies and automation of a server motherboard with SPEA flying probe system

Test methodologies and automation of a server motherboard with SPEA flying probe system. The topic of the thesis work described here was the analysis and research of the best strategies for automation and testing of a motherboard. The work was carried out at SPEA, a leading company in the design and construction of automatic machinery for testing electronic devices. Testing represents a fundamental part in the development of electronic systems. The aim of the project was, indeed, the development of a program to test the correct functioning of the motherboard using the SPEA Flying Probe 4080 as Board Automatic Test Equipment. This machine uses 8 mobile probes to contact the Unit Under Test and make electrical measurements and has countless advantages: thanks to the speed and precision of the probes it guarantees the maximum productivity obtainable with a moving probe tester. The project has been developed in two phases: the testing program generation and the test itself. Because of the tested motherboard size, it was necessary to design two test programs and then combine them in a single multi project. Two types of tests have been performed on the board: the In Circuit Test, which inspects the correct functioning of the individual components, and the Functional Test verifying the proper functioning of the board as a whole. Moreover, the functional test includes in turns the Power On and the flashing phase of some microcontrollers on the board. In parallel with the development of the test program, an automation analysis is made toward a completely automatized test procedure thus minimizing the manual work. To achieve this goal, the ”in line” mechanism is used which allows, when required by the test phase, the board to be automatically inserted into the Flying Probe 4080 system via a conveyor. Thus, it has been used a system providing the connection of power supplies to the 4080 system interface, connected in turns to the side one via a specially designed cable. A carrier, directly contacting the side interface, has a Pogo pins block bonding directly to the power supply points on the board. A relay on the same interface allows to power the board only when required by the test program, to autonomously controls the whole system. This way, 91% of components could be tested generating the two test programs. Then, 6% are not mounted components, therefore impossible to test. Finally, 3% of board’s components cannot be tested because of critical circuit configurations or the impossibility of contacting the component via the 4080. To reach 91% of tested components, it was necessary to perform a debugging phase to find suitable and stable tests. Finally, an analysis was carried out to try to optimize the results obtained: that is, to try to have a stable test program that is executed in the shortest possible time. The time shrink originated from increasing the probes movement speed, reducing measurement times in tests while maintaining stable measurements and optimizing the probe paths. Therefore, while initially the program runed within almost 15 minutes, the optimization results in a 9 minute run. In the functional test, time optimization was obtained by increasing the programming frequency of the microcontrollers. The program optimization, as carried out during the thesis project, does represent a foundamental step. The obtained results are discussed with the client and the installation of the application has been carried out ”on site”.