Mid Sweden University

Surface roughness is of great importance in fields, such as tribology, semiconductor technology and medicine. Stylus techniques, in which a stylus is drawn along the surface and the vertical movement of the stylus is recorded, have been used traditionally in measuring surface roughness. Non-contact methods, such as optical ones, have the advantage that they can be used for the in-process measurement of surface roughness. In this paper, results of the measurement of surface roughness using angular speckle-correlation on machined surfaces are presented. Surfaces of approximately 1.6 < R-a < 6.3 mu m have been measured, the surfaces being classified in the same manner as when using a stylus instrument. ASC is a technique that also allows in-process measurement of the roughness of surfaces on machined surfaces. A new technique to achieve increased repeatability by using an angle detection unit is also presented in this paper. (c) 2006 Elsevier B.V. All rights reserved.

Test Access Port and Boundary-Scan Architecture, IEEE Std. 1149.1, was developed to ease the test of printed circuit board assemblies (PCBAs). The development of packaging technology and the increasing functionality of a circuit have made traditional testing methods, such as in-circuit tests and functional testing through edge connectors much more difficult or even impossible. Mixed-Signal Test Bus, IEEE Std. 1149.4, which is a further development of IEEE Std. 1149.1 has been developed to enable the testing of analog components and analog interconnects on PCBAs. IEEE Std. 1149.4 compliant circuits contain an analog bus and analog switches. Techniques applicable to the measurement of impedances via IEEE Std. 1149.4 compliant circuits are presented. A filter has been tested and the results are promising. It has been shown by both measurement and simulation that switching impedances can be managed in such a manner that the influence of deviations from their nominal value can be estimated.

This paper presents a non-contact method for making relative measurements of the resistance of surface mounted resistors. An application of this technique is in automatic test equipment, i.e. within the limitations of resolution and accuracy of the measuring system it is possible to detect if incorrect resistor values are mounted on a printed board assembly. Measurements are made on two specially designed test boards. Two different measurement systems are used of which one is based on thermopiles and the other is a heat camera equipped with a QWIP (Quantum Well Intersubband Photodetector) detector. The detection of a minimum change of resistance, corresponding to a change of approximately 5 mW in dissipated electrical power, was achieved. Simulations of resistor board systems using; THERMIC 6.6, THERMICPCB 6.6, and Flotherm 3.2; and a dissipation power model are presented as a demonstration of predictions of the thermal fingerprint of a circuit board.