Apparatus for maintaining reserve bonding wire

Apparatus for feeding lead wire from a spool to the capillary wire holding tool of a lead wire bonding machine comprising:

• spool mounting means for mounting a spool of lead wire for rotation around the axis of the spool;
• spool drive motor means operatively coupled to the spool mounting means for rotating a spool mounted on the spool mounting means and thereby unwinding and feeding lead wire from a spool;
• control means for turning said spool drive motor on and off;
• slack chamber means for maintaining a reserve of lead wire in untangled condition, said slack chamber means comprising a housing enclosure of first and second plates and side walls spacing said plates and completing the housing enclosure, inlet guide means formed in one side wall of the housing enclosure for guiding lead wire into the slack chamber means and an outlet guide formed in the opposite side wall of the housing enclosure for guiding lead wire out of the slack chamber means toward the capillary tool of a ball bonding machine, said slack chamber means formed with a plurality of lead wire sensing means operatively arranged in a row in the housing enclosure offset from and substantially perpendicular to an imaginary line between the inlet and outlet guides, said row of a plurality of wire sensing means being intermediate the inlet and outlet guides;
• and means for directing a gaseous flow into the slack chamber means along the direction of the row of wire sensing means whereby a length of lead wire passing through the slack chamber means between the inlet guide and outlet guide is maintained and suspended in said gaseous flow in a configuration offset from the imaginary line joining the inlet and outlet guides for maintaining a slack reserve of lead wire in slightly tensioned and untangled condition for use in successive bonding operations by the bonding machine;
• said row of wire sensing means comprising at least a first shorter limit wire sensing means closer to the imaginary line between the inlet and outlet guides, said first wire sensing means operatively coupled with the spool drive motor means for turning on said spool drive motor means and thereby feeding lead wire into the slack chamber means for increasing the offset of lead wire and therefore the length of slack reserve whenever the offset and slack reserve length are reduced to the point where the lead wire is sensed in the vicinity of said first shorter limit wire sensing means, and at least a second longer limit wire sensing means along said row beyond the first wire sensing means, said second wire sensing means operatively coupled to the spool drive motor means for turning off the spool drive motor means and stopping the feed of lead wire into the slack chamber means when the offset of the lead wire suspended in the gaseous flow and therefore the slack reserve length has increased to the point where the lead wire is sensed in the vicinity of the second longer limit wire sensing means, whereby a slack reserve of lead wire is maintained in the slack chamber means within a specified range of length under slight tension and in untangled condition for delivery to the capillary wire holding tool of the lead wire bonding machine during bonding operations;
• axial drive motor means operatively coupled to said spool mounting means for translating a spool mounted on said spool mounting means in an axial direction, said spool mounting means comprising a rim having an optical index formed thereon, spool rotation optical sensor means operatively mounted and coupled to the spool mounting means for detecting the optical index upon each rotation of the spool and for generating a corresponding signal, counting logic means operatively coupling said spool rotation optical sensor signals and the axial drive motor means for actuating said axial dirve motor means each predetermined number of rotations for maintaining the wire feeding from the spool into the inlet guide substantially at right angles to the axis of the spool and tangent to the spool surface.

An apparatus for feeding bonding lead wire from a spool to the capillary wire holding tool of a lead wire bonding machine comprising:

• spool mounting means for mounting the spool for rotation about the spool axis;
• spool motor means coupled to the spool mounting means for driving and rotating a spool about the spool axis;
• control means operatively coupled to said spool motor means for turning on and off said spool motor means thereby advancing lead wire from the spool in predetermined increments;
• slack chamber means positioned for receiving lead wire fed from a spool and for holding and maintaining ready for delivery a reserve length of lead wire within a predetermined range of length, said slack chamber means comprising a housing enclosure having a top plate and a bottom plate spaced from the top plate, said top plate removable for placement of lead wire through the slack chamber means, said housing also having an inlet side wall with an inlet guide for guiding lead wire into the slack chamber means, and an outlet side wall with an outlet guide for guiding lead wire from the slack chamber means, said slack chamber means further comprising a plurality of optical sensors arranged in a row substantially perpendicular to and offset from an imaginary line between the inlet and outlet guides of the slack chamber means, said row of optical sensors operatively positioned in the slack chamber means between the inlet and outlet guides;
• means for delivering a flow of gas into the slack chamber means in the direction along the row of optical sensors for maintaining a reserve of lead wire passing through the slack chamber means from the inlet guide to the outlet guide in an offset configuration along the row of optical sensors, said offset configuration of reserve lead wire being maintained under slight tension thereby maintaining the reserve of lead wire in untangled condition for delivery to the capillary wire holding tool of the bonding machine;
• said row of optical sensors comprising an inner limit optical sensor and an outer limit optical sensor operatively arranged in the slack chamber means to define an inner and outer limit of offset of the lead wire maintained by the flow of gas for maintaining a reserve length of lead wire in untangled condition within a desired range;
• said inner and outer limit optical sensors of said row being electrically coupled to said control means for the spool motor means so that the inner limit optical sensor defining the inner limit of offset of the lead wire in the slack chamber means turns on the spool motor means when the lead wire is sensed in the vicinity of the inner limit optical sensor for delivering further reserve lead wire to the slack chamber means, and so that the outer limit optical sensor turns off the spool motor means when the lead wire is sensed in the vicinity of the outer limit optical sensor whereby an adequate reserve of lead wire is maintained in said slack chamber within the desired range;
• said spool mounting means further comprising axial drive means for translating said spool in an axial direction to maintain the angle of entry of lead wire from the spool into the inlet guide of the slack chamber means within a desired angular range.