Missing wire detector
AssigneeHughes Aircraft Company
InventorRobert Zimmerman
Life of this patent
Estimating the term…
Abstract
The absence of a wire (40) in proper position under the bonding tool (32) of an ultrasonic wire bonder is detected by energizing the bonder transducer (14) while the wire is pulled to break it after the second bond (B) has been made. The pulling of the wire to break it changes the transducer impedance, which is monitored to signal presence or absence of a wire in its proper location.
Claims16
For use in a wire bonder wherein a bonding tool is moved relative to the wire and away from a prior bond to feed fresh wire to the tool, and wherein the wire is then pulled to break it at said prior bond, a method of detecting lost wire comprising the steps of:
- moving the wire relative to the prior bond in a breaking step, thereby tending to exert a breaking force on the wire to break the wire, and
- detecting the loss of the wire by monitoring the force exerted on the wire during said breaking step.
In a bonding system wherein a bonding tool is moved relative to a worktable carrying an element to which a wire is to be bonded by using the tool to press a wire against the element, wherein said wire is broken after completion of a bond by motion of the worktable and bond relative to the bonding tool to cause a wire breaking force to be exerted on and to break the wire, apparatus for detecting absence of wire at the bonding tool, said apparatus comprising:
- means for sensing said force exerted on said wire by motion of the worktable and bond relative to the bonding tool, and
- means for signaling a missing wire when the sensed force exerted on the wire is less than a selected amount.
An ultrasonic wire bonding system comprising:
- a worktable adapted to carry an element to which a wire is to be ultrasonically bonded,
- a bonder support,
- means for moving the bonder support relative to the worktable,
- a transducer mounted to the bonder support,
- a bonder tool mounted on the bonder support and connected to the transducer,
- means for energizing the transducer,
- clamp means on the bonder support for clamping to the support a wire that is to be bonded,
- said means for moving the bonder support relative to the worktable and transducer comprising means for moving the worktable and an element thereon relative to the bonder support while the wire is clamped, to thereby exert a wire breaking tensile force on a wire bonded to an element on the worktable and cause the wire to break, and
- means for detecting loss of wire comprising:
- means for detecting said tensile force, and
- means responsive to said detecting means for indicating a missing wire when the detected tensile force is below a selected minimum.
Dependencies are inferred from the claim text.