GB1319045A - Substrate position determination structure and method - Google Patents

Abstract

1319045 Measuring displacement electrically MICROSYSTEMS INTERNATIONAL Ltd 6 March 1970 [3 Sept 1971] 10255/72 Heading G1N Means for accurately positioning a laser cutting beam or a spark discharge erosion beam relative to a sheet of substrate material comprises a resistive strip on the surface of the substrate which is progressively cut by the beam as it is moved from one edge of the strip to the other, whilst the resistance of the strip is being measured. When the resistance reaches a very high value the beam is at the remote edge of the strip and is stopped, defining a particular coordinate position of the cutting beam relative to the substrate surface. This is repeated in a perpendicular direction to determine a second co-ordinate position of the beam. As shown (Fig. 6) for cutting a substrate sheet 5 with respect to electronic circuits pivoted on it, a resistive strip 1 has its resistance measured between end pads 2, 2 by feelers 7, 7 whilst it is cut transversely by movement of a laser beam located in the area X, under the control of motor 11. When the measured resistance reaches a predetermined high value, the beam position defines a base co-ordinate distance along the abscissa direction of substrate 5. The beam is then moved by motor 12 in the perpendicular direction to the area Y and the process repeated for the stepped portion of resistive strip 4. The next stopping point defines the base co-ordinate distance along the ordinate direction of substrate 5. Hence the origin and co-ordinate directions for subsequent automatic movement of the cutting beam are accurately defined.