Wire bonding apparatus and bonding method

Abstract

Provided is a wire bonding apparatus capable of performing high-speed wedge wire bonding, the apparatus including: a bonding tool having a through hole and a pressing surface for pressing a wire; a clamper for holding the wire; and a control unit. The control unit includes: wire tail extension unit that moves the bonding tool, after wedge bonding of the wire to a first lead, upward and along a second straight line connecting a second pad and a second lead, and causes the wire to extend from the through hole in a direction along the second straight line from the second pad to the second lead; and tail cut unit that, after causing the wire tail to extend, cuts the wire tail by moving the bonding tool in the direction along the second straight line connecting the second pad and the second lead while the clamper is closed.

1 . A wire bonding method of connecting a plurality of first bonding points and a plurality of second bonding points with a wire, the method comprising:
 a step of preparing a wire bonding apparatus comprising:
 a bar-shaped bonding tool having a through hole in which the wire is inserted, and a pressing surface provided at a periphery of the through hole at a tip of the bonding tool and configured to press the wire against a bonding target, the through hole extending along a longitudinal direction of the bonding tool; and 
 a clamper configured to hold the wire; 
   a wire tail extension step of, after bonding the wire to a previous one of the second bonding points, moving the bonding tool upward while the clamper is opened, moving the bonding tool along a straight line directed from a succeeding one of the first bonding points to a succeeding one of the second bonding points by a predetermined distance, and causing the wire to extend from the through hole of the bonding tool in the direction along the straight line directed from the succeeding first bonding point to the succeeding second bonding point; and   a tail cut step of, after causing the wire tail to extend, cutting the wire tail by moving the bonding tool in the direction along the straight line directed from the succeeding first bonding point to the succeeding second bonding point while the clamper is closed.   
     
     
         2 . The wire bonding method according to  claim 1 , wherein
 the bonding apparatus further comprises a folding station having a stepped portion for catching the wire tail extending from the tip of the bonding tool, and   the method further comprises:   a wire tail folding step of, after moving the bonding tool to the folding station and positioning the wire tail along the stepped portion, moving the bonding tool toward the succeeding second bonding point along the straight line directed from the succeeding first bonding point to the succeeding second bonding point, thereby causing the wire tail to be flexed toward the succeeding first bonding point.   
     
     
         3 . The wire bonding method according to  claim 2 , wherein
 the wire tail is formed in the wire tail extension step and the tail cut step, when an angle between a first straight line and a second straight line is smaller than a predetermined angle, the first straight line connecting a previous one of the first bonding points and the previous second bonding point, the second straight line connecting the succeeding first bonding point and the succeeding second bonding point; and   the wire tail is formed in the wire tail folding step, when the angle between the first straight line and the second straight line is equal to or greater than the predetermined angle.   
     
     
         4 . The wire bonding method according to  claim 1 , wherein
 the pressing surface is an annular flat surface, and   in the wire tail extension step, the bonding tool is moved such that the wire tail is slightly longer than an external radius of the pressing surface.   
     
     
         5 . The wire bonding method according to  claim 4 , wherein
 in the wire tail extension step, the bonding tool is moved horizontally by a predetermined XY-direction distance along the straight line directed from the succeeding first bonding point to the succeeding second bonding point, after moving the bonding tool upward by a predetermined Z-direction distance.   
     
     
         6 . The wire bonding method according to  claim 4 , wherein
 in the wire tail extension step, the bonding tool is moved obliquely upward by a predetermined oblique distance along the straight line directed from the succeeding first bonding point to the succeeding second bonding point.   
     
     
         7 . The wire bonding method according to  claim 4 , wherein
 the plurality of first bonding points are leads on a substrate, and   the plurality of second bonding points are pads on a chip.   
     
     
         8 . The wire bonding method according to  claim 4 , wherein
 when a plurality of chips are disposed on a common substrate, and a plurality of pads of each chip and leads on the substrate corresponding to the pads are connected with a wire,   bonding is started after a last one of the pads on a previous one of the chips and a lead on the substrate corresponding to this pad are connected with a wire, from a set of pads and leads of a subsequent one of the chips on which a pad and a lead corresponding to this pad are disposed along a direction directed from the last pad on the previous chip to the lead corresponding to this last pad.   
     
     
         9 . The wire bonding apparatus according to  claim 4 , wherein
 when a plurality of chips are disposed on a common substrate, and a plurality of pads of each chip and leads on the substrate corresponding to the pads are connected with a wire,   bonding is sequentially performed to each of sets of pads and leads respectively corresponding to the pads, the pads and the leads in each set being connected by lines in a similar direction.   
     
     
         10 . The wire bonding method according to  claim 4 , wherein
 the wire tail extension step moves the bonding tool horizontally by a predetermined XY-direction distance along the straight line directed from the succeeding first bonding point to the succeeding second bonding point, after moving the bonding tool upward by a predetermined Z-direction distance, and horizontally from the second bonding point to the first bonding by a predetermined XY-direction distance.