Thiele, Georg

The increasing clock frequencies have led to new fault effects of production defects. These so called "delay faults" have to be adressed by todays production test. The research work which was supported by Philips Semiconductors, Hamburg, provides an introduction into the problems of delay fault testing in a production environment. A test pattern generator for path delay faults has been developed. Furthermore, different classes of test quality have been defined. The investigations focus on the properties of this classes of test quality. At the end of the thesis, the next fault effects, so called signal integrity faults, are introduced which will occur as the operating clocks continue to increase. Based on their relationship with delay faults it is discussed how a test pattern generator for such faults could be constructed.

The visual observation of the metal transfer and the recording of electrical parameters of the pulsed gas metal arc welding are very important. These methods are used in all phases of research, development and application. Normally, high speed cameras in combination with an additionally lighting unit were used for the visual observation of the metal transfer. However, these systems have some disadvantages for many applications. Furthermore, no methods exist for the analysis of the recorded visual and electrical data.In this work the development and conversion of a concept for the visual online observation of all states of the metal transfer in combination with the simultanious and synchronized measurement of relevant electrical welding process signals (current, voltage, etc.) is described. Additionally, the concept contains the automatic analysis of the recorded data refering to relevant visual parameters of the metal transfer and relevant parameters of the electrical welding process signals. Aim of the concept is the inspection, analysis, optimisation and documentation of the welding process.In detail, this work focuses on the following tasks:* The development of a concept for the visual observation of all states of the metal transfer incombination with the simultanious and synchronized measurement of relevant electrical weldingprocess signals.* The analysis of the high dynamic CMOS technology based on the applicability of differrentCMOS cameras for visual observation of the metal transfer. Important points of the analysiswere the brightness dynamic of the arc, the velocity and the acceleration of the metal transferdrops. For a better evaluation of the characteristic and results of the CMOS technology, it hasben compared with the CCD technology (on the basis of a CCD camera).* The development of methods for the automatic calculation of characteristic parameters out ofthe measured electrical welding signals.* The development of methods for the automatic extraction of visual parameters out of the recordedmetal transfer images.* The development of methods for the automatic preparation and analysis of the caluculated visualand electrical parameters.* The analysis of the developed methods and the entire sensor systems on their ability for a controlof the process using the visual and electrical parameters as basis for future works.

Thiele, Georg

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