Lehrstuhl für Fertigungstechnologie, Universität Erlangen-Nürnberg

Image Processing System Employed for the Detection of Geometrical Lead-Parameters of SMDs

Datum: 27.10.1999



  • Prof. Dr.-Ing. Dr.h.c. M. Geiger
  • Prof. em. Dr.-Ing. H. Brand

Within this Dr.-thesis a new measurement principle for the detection of Gull-Wing-Lead parameters has been introduced. The aim was to detect and compute a complete set of geometrical lead-parameters by evaluation of a single high-resolution image. Thus a quality assurance tool for joining methods requiring high coplanarity tolerances has been developed. The measurement principle is basing on the so-called "non-frontal" camera position where the normal-direction of the SMD is tilted twice against the camera axis. The SMD is mounted on a linear DC-servo module that moves the component in front of the CCD-line. The so generated line-scan is evaluated within two steps. First, the periodicity of the lead-row is computed by employing a wavelet-algorithm. Because of the non-frontal view, every bad positioned lead causes an error in periodicity. Second, the so detected badly positioned leads are examined in a more accurate way. After an edge-detection and the computation of the related regression straight lines, position and geometrical parameters of the lead can be extracted.