Bonding apparatus with means and method for automatic calibration using pattern recognition

In a wire bonding apparatus which incorporates a pattern recognition system for generating signatures and a rotatable pedestal for carrying a package to be wire bonded, said apparatus having a system reference, a method of automatically determining the center of rotation of said pedestal with respect to said system reference after a period of operation of said apparatus, comprising

• initially determining the pedestal center of rotation with said pedestal at a first angle and storing same,
• choosing a point on said package and obtaining and storing a first signature for said point;
• rotating said pedestal to angles of 90.degree., 180.degree. and 270.degree. relative to said first angle and obtaining and storing second, third and fourth signatures for said point corresponding to said 90.degree., 180.degree. and 270.degree. angles, thereby accumulating four 90.degree. interval signatures;
• automatically running packages and performing bonding operations on each of said packages, utilizing the stored center of rotation;
• every N packages, automatically re-calibrating the center of rotation and storing a newly determined center of rotation, said re-calibrating including finding said first signature and automatically;
• determining its corresponding position;
• rotating said pedestal 90.degree. and finding said second signature and determining its corresponding position;
• rotating said pedestal another 90.degree. and finding said third signature and determining its corresponding position and rotating said pedestal another 90.degree.;
• and, finding said fourth signature and determining its corresponding position, and
• automatically calculating the pedestal center of rotation as a function of said four determined positions.

Wedge wire bonding apparatus, said apparatus having a pedestal for carrying a package through predetermined angles, a pattern recognition system for generating signatures, and bonding means for carrying out pre-determined bonding operations;

• said apparatus further having auto calibration means for automatically re-calibrating the pedestal center of rotation, said auto calibration means comprising:
• storage means for storing a plurality of respective signatures obtained by said pattern recongition system and each representing a pre-determined point on said package at respective pedestal angles,
• rotation means for automatically rotating said pedestal to about said respective angles,
• finding means for automatically finding at each of said angles the signature corresponding to the stored signature for each said angle and automatically determining the location of each said found signature, and
• calculating means for automatically calculating the center of rotation of said pedestal as a function of said determined locations.