This postgraduate specialist thesis deals with the test approaches, methods, technologies and processes in the production testing cycle of complex electronic devices and systems. The general topics in the introductory chapters are followed by a practical example of a realization of such a test system with typical problems and solving methods we are facing.
In the central part, the entire design, verification and final implementation of the individual phases of the automatic test system ATS for products testing in mass production are presented in general. From the planning and realization point of view, this is a multiple stage process which is logically structured into separate individual and independent test groups or test levels. This division usually covers ICT and Boundary scan level testing for connections integrity on the board and component level, firmware programming, functional, thermal, system and configuration level. Each of these levels is an important step in the production cycle of the device and must comply with certain specific characteristics. The process of transition between these levels is accurately controlled and pre-determined. The input condition of each subsequent test level is a successfully completed previous test level. Process control is ensured by test system architecture and automated test software application GUI. This application operates in conjunction with the network infrastructure, test server and data base information system for storing test results (SQL-DB).
The practical implementation of the entire manufacturing test system solution is presented with selected device from microwave data transmission area, developed and produced by Aviat Networks, where I also work. My work here mainly refers to the areas covered by the main title theme. The device for which the practical test system solution was developed is a digital signal processing unit or the so-called Microwave router CTR8540. This is one of the major projects where I was actively involved from the beginning in the development phase of a complete test system, from the initial concept and ideas to the final realization.
The focus of this work is on input test requirements and specifications, testing methods and approaches, individual test levels presentation, test applications development, final verification and implementation, test results analysis and on the real problems solving before and during the production phase.
The final part gives some options for optimizations and improvements of the test process, which is quite dynamic and still evolving in the context of new technologies and approaches. When we are introducing such changes, we must always take into account a larger number of factors (financial, temporal, technical and available resources). This is especially important if a test process has been previously already consolidated. Any unscheduled production testing stoppage means an additional cost, worse balance and various other negative impacts. Therefore, such changes require good reasons and well-tested solutions.
Realization and implementation of the originally specified requirements or any subsequent changes at the end of the development cycle always require consistent verification testing of all functionalities, reliability and repeatability. This is usually done in the context of cyclical testing of a pre-determined number of test samples, the so-called R&R testing phase. Based on the analysis of R&R test results, we can assess the estimated probability distribution and statistical performance for the wider test units population, the so-called first pass yield (FPY). The ultimate goal of any automated test system is as far as possible good, reliable, high-quality and time-efficient pre-tested product. It is also a warranty for the desired operation of the device or system at the customer.