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Title: Multiface wire bonding method and tool
Claims: What is claimed is: 1. Wire bonding apparatus comprising a bonding wedge having first and second wire contact areas of mutually different orientation, a wire guide having a feed end adjacent said contact areas, and means for movably mounting said guide with respect to said wedge for motion between first and second positions at which a wire extending along said guide and from said feed end is in registry with said first and second contact areas, respectively, and one at a time. 2. The apparatus of claim 1 wherein said first and second contact areas are of mutually different inclination. 3. The apparatus of claim 2 wherein said motion of said guide is transverse to the longitudinal extent of a wire extending along said guide. 4. An ultrasonic wire bonding wedge comprising first and second side by side working heads having wire bonding surfaces that are oppositely inclined with respect to each other and mutually displaced in a direction transverse to the longitudinal extent of a wire to be bonded. 5. The wedge of claim 4 wherein one of said surfaces inclines upwardly and rearwardly, and wherein the other of said surfaces inclines upwardly and forwardly. 6. The wedge of claim 4 wherein one of said surfaces includes a downwardly projecting lip at a rearward end thereof. 7. The wedge of claim 4 wherein said workinig heads are formed integrally with each other. 8. A wire bonding tool adapted to bond a wire to a workpiece at points spaced along the length of the wire, said tool comprising a first working head providing a first wire contact area having a configuration constructed and arranged for making a first bond of said wire without significantly weakening the wire at said first bond, a second working head mounted in closed juxtaposition to said first head, said second head providing a second wire contact area having a configuration constructed and arranged for making a second bond of said wire and for weakening said wire at said second bond, said second wire contact area being displaced from said first wire contact area in a direction transverse to said length of the wire, whereby first and second bonds of said wire may be made by shifting the wire both longitudinally and laterally relative to said tool to place a first part of said wire in contact with said first wire contact area and to place a second part of said wire in contact with said second wire contact area, and whereby said wire may be readily parted at said second bond. 9. The tool of claim 8 including an elongated tool body carrying said working heads and having a longitudinal axis, said first and second wire contact areas having mutually different inclinations with respect to said axis. 10. The tool of claim 9 wherein said first and second contact areas are inclined with respect to said axis in mutually opposite senses. 11. The tool of claim 8 wherein said first wire contact area inclines upwardly and rearwardly with respect to said tool body and wherein said second wire contact area inclines upwardly and forwardly with respect to said tool body. 12. The tool of claim 8 wherein said second wire contact area includes a wire weakening portion having a relatively small radius of curvature to facilitate parting of said wire at an outer end of said second bond. 13. The tool of claim 8 including an elongated tool body carrying said working heads and having a longitudinal axis, said first wire contact area terminating at a rearward end thereof in a convex curve having a relatively large radius of curvature, said second wire contact area terminating at a rearward end thereof in a convex curve having a relatively small radius of curvature. 14. The tool of claim 13 including a tool body carrying said working heads and defining a longitudinal axis of the tool, at least one of said surfaces extending substantially normal to said axis. 15. The tool of claim 8 wherein said working heads are positioned side by side with respect to the longitudinal extent of the wire. 16. The tool of claim 15 wherein said working heads are formed integrally with one another. 17. The tool of claim 8 wherein at least one of said wire contact areas is formed with a wire positioning groove therein extending longitudinally of the wire to be bonded. 18. The tool of claim 8 including transducer means connected thereto for vibrating said working heads. 19. A method for bonding a wire to a workpiece at a plurality of points mutually spaced along the length of the wire comprising the steps of pressing said wire over a first section of its length that is to form a first bond and deforming said section in a pattern of deformation that decreases in magnitude of deformation from a forward end of said first bond toward a rearward end thereof, and pressing said wire against said workpiece at a second section of the wire that is to form another bond and deforming said second section in a pattern of deformation that increases in magnitude of deformation from a forward end of said second section toward a rearward end of said second section, whereby inner ends of said bonded wire sections are deformed less than outer ends of said bonded sections to provide greater strength at such inner ends than at such outer ends, concomitantly facilitating parting of the wire at the rearward end of said second section. 20. The method of claim 19 wherein said step of deforming said first section comprises effecting a pattern of deformation that tapers rearwardly from a greater depth of deformation at a forward end of said first section to a lesser depth of deformation at an inner end of said first section. 21. The method of claim 19 wherein said step of deforming said second section comprises deforming the wire at said second section with a deformation that tapers from a lesser depth of deformation at an inner end of said second section toward a greater depth of deformation at an outer end of said second section. 22. The method of claim 19 wherein at least one of said steps of pressing the wire against the workpiece icludes the step of imparting a vibratory motion to the wire while it is so pressed. 23. The method of claim 19 wherein said step of deforming said second section includes the step of effecting a deformation that is significantly greater at an outer end of said second section than the deformation at an inner end of said second section, whereby said wire may be readily severed at such end of significantly greater deformation by applying a tensile force thereto. 24. The method of claim 19 wherein said steps of deforming the wire comprise the steps of engaging with said wire first and second working heads of mutually different configurations, and including the step of shifting the wire with respect to said working heads in both longitudinal and lateral directions between said first and second deforming steps. 25. The method of ultrasonically bonding a wire to two spaced points of a workpiece comprising the steps of contacting a first section of the wire with a first working head of a bonding wedge, vibrating said first working head to effect a first bond, shifting said bonding wedge rearwardly and transversely with respect to the longitudinal extent of said wire, contacting a second section of the wire with a second working head of the shifted bonding wedge, and vibrating the second working head to effect a second bond. 26. The method of claim 25 wherein said steps of contacting said first section comprises contacting the wire with a first working head surface that inclines upwardly and rearwardly, and wherein said step of contacting said second section comprises contacting the wire with a second working head surface that inclines upwardly and forwardly. 27. The method of ultrasonically bonding a wire to two spaced points of a workpiece comprising the steps of contacting a first section of the wire with a first working head of a bonding wedge, vibrating said first working head to effect a first bond, shifting said bonding wedge rearwardly and laterally with respect to the wire, contacting a second section of the wire with a second working head of the shifted bonding wedge, vibrating the second working head to effect a second bond, and parting said wire at said second bond and then shifting the bonding wedge laterally with respect to the wire in a direction opposite to the direction of said first mentioned lateral shifting in order to prepare for further bonds. 28. Wire bonding apparatus comprising a support, a work holder mounted to the support, a bonding wedge movably mounted to said support, said wedge having first and second working heads mounted in side by side relation and adapted to be moved to and from a workpiece carried by the work holder, a wire guide movably mounted to said support and having a wire feed adjacent said working heads, and means for effecting relative motion of said bonding wedge and wire guide transversely to the longitudinal extent of a wire to be bonded to position said wire feed in operative relation with respect to one or the other, but not both, of said working heads. 29. The apparatus of claim 28 wherein said wire guide comprises a wire feed tube having an axis inclined with respect to the axis of said bonding wedge and having a feed end thereof in close proximity to said working heads, and wherein said means for effecting relative lateral motion of said bonding wedge and wire guide comprises means for shifting said wire feed tube transversely of its own axis. 30. The apparatus of claim 29 wherein said means for shifting said feed tube comprises a wire shifter shaft movably mounted with respect to said bonding wedge, and means for securing said wire feed tube to said shifter shaft. 31. Wire bonding apparatus comprising a support, a work holder mounted to the support, a bonding wedge movably mounted to said support, said wedge having first and second working heads mounted in side by side relation and adapted to be moved to and from a workpiece carried by the work holder, a wire guide movably mounted to said support and having a wire feed adjacent said working heads, and means for effecting relative lateral motion of said bonding wedge and wire guide to position said wire feed in operative relation with respect to one or the other of said working heads, said wire guide comprising a wire feed tube having an axis inclined with respect to the axis of said bonding wedge and having a feed end thereof in close proximity to said working heads, and wherein said means for effecting relative lateral motion of said bonding wedge and wire guide comprises means for laterally shifting said wire feed tube, said means for shifting said feed tube comprising a wire shifter shaft movably mounted with respect to said bonding wedge, and means for securing said wire feed tube to said shifter shaft, being mounted for pivotal motion with respect to said bonding wedge about a pivot axis that is angulated with respect to said bonding wedge. 32. The apparatus of claim 31 wherein said pivot axis of said shifter shaft coincides with the longitudinal axis of said shaft and wherein said wire feed tube projects at an angle from an end of said shaft, whereby pivotal motion of said shaft about its axis will swing an end of said wire feed tube in a lateral direction with respect to said working heads. 33. The apparatus of claim 29 including a bonding wedge mounting block fixed to the bonding wedge for movably mounting the wedge to said support, said means for laterally shifting said wire feed tube comprising a crossarm pivoted to said mounting block, a return spring connected between said bonding wedge mounting block and one side of the crossarm, and a motive device connected to pivot the crossarm in opposition to the return spring. 34. Ultrasonic bonding apparatus comprising a support, a transducer tool cone mounted to the support for motion to and from a workpiece, a transducer connected to impart vibration to said tool cone, a bonding wedge carried by said tool cone and projecting therefrom, said bonding wedge comprising a pair of side by side working heads, said bonding wedge having an elongated body with a longitudinal axis, a wire shifter shaft mounted for pivotal motion relative to said tool cone about a second axis substantially normal to said longitudinal axis, a wire feed tube fixed to said shifter shaft and having a feed end positioned closely adjacent said working heads, and means for effecting limited pivotal motion of said shifter shaft about said second axis to effect lateral shifting of said feed end of said wire feed tube and also of a wire extending therethrough, with respect to said working heads, whereby a wire extending through said feed tube may be operatively positioned with respect to one or the other of said working heads. 35. The apparatus of claim 34 wherein said working heads have mutually different configurations to provide mutually different bonds upon a wire extending through said feed tube. 36. The apparatus of claim 34 wherein said working heads have mutually different inclinations with respect to the longitudinal axis of said bonding wedge. 37. The apparatus of claim 34 wherein said working heads are oppositely inclined with respect to the longitudinal extent of a wire extending through said feed tube. 38. The apparatus of claim 34 including means for adjustably moving said wire feed tube toward and away from said working heads. 39. The apparatus of claim 34 wherein at least part of one of said working heads includes a flat surface substantially perpendicular to the longitudinal axis of said bonding wedge. Other info: Inventors: Larrison, John E. (Costa Mesa, CA, US) Application Number: 510416 Filing Date: 1974-09-30 Publication_date: 1976-01-27 Assignee: Primary Class(es): 228/110.1 228/1.1, 257/E21.518 Other Classes: US Patent Ref:
Other Refs: Primary Examiner: Smith, Al Lawrence Assistant Examiner: Joyce, Margaret Attorney: Rothenberg; Allan |
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