JP6270920B2 - Wire feeding mechanism in wire bonding equipment - Google Patents

Description

The present invention relates to a wire payout mechanism in a wire bonding apparatus, and more particularly to a wire payout mechanism in a wire bonding apparatus capable of always performing an operation of pulling out a wire from a tip of a capillary under the same conditions in a preparation stage for starting wire bonding.

  Conventionally, wire bonding using gold wires has been the mainstream in semiconductor assembly processes, but copper wires and silver wires (hereinafter these wires are collectively referred to as non-gold wire wires) are cheaper in material cost than gold wires. ) Bonding is being performed.

  However, in bonding using a copper wire as a non-gold wire, copper and a copper ball of copper oxide are formed by reaction of copper and oxygen in the atmosphere in which the wire bonding apparatus is installed during ball formation by spark discharge. Since copper oxide has a higher hardness than copper, damage may be caused under the pad when the copper ball and the IC chip pad are joined. In addition, the oxidized copper ball may be discolored or decentered, which may adversely affect bonding quality. Even when a silver wire is used as the non-gold wire, there is a problem similar to the case where a copper wire is used. A ball formed at the tip of the wire by spark discharge is referred to as a free air ball (hereinafter referred to as FAB).

  For this reason, in Patent Document 1, when forming a FAB (free air ball) in an inert gas atmosphere, the FAB is stabilized while suppressing oxidation of the FAB, and the discharge gap length between the capillary and the spark rod is determined. A wire bonding apparatus that can easily set the size of an inert gas atmosphere is disclosed.

  Patent Document 2 is directed to a wire feeding mechanism in which tension is applied to a wire fed from the tip of a capillary from a reel to a clamp member during execution of wire bonding, and the tension is applied. The wire is sent out toward the bonding surface of the member to be bonded by a wire guide provided in the wire transfer path. Patent Literature 2 discloses a wire bonding apparatus that removes the adverse effects caused by the wire fed from the tip of the capillary being fed toward the bonding surface of a member to be bonded by the wire guide. According to Patent Document 2, since the wire receives a tension force and contacts and / or slides on the fixed surface of the wire guide, the fixed surface is easily scratched, and the scratch causes friction on the wire. Increase power. Defects such as bonding mistakes due to kinks such as bending of the wire due to an increase in frictional force on the wire occur. For this reason, by providing a substantially cylindrical guide body that can rotate as the wire guide rotates as the wire is transferred, the frictional force caused by contact and / or sliding between the wire receiving the tension force and the wire guide is reduced. Thus, a bonding error caused by the wire guide is eliminated.

  Patent Document 3 discloses a cleaning method for cleaning a capillary of a wire bonding apparatus. According to Patent Document 3, a phenomenon occurs in which a non-gold wire comes into contact with an inner surface of a capillary and the inner surface of the capillary is contaminated, and a tungsten wire is inserted into the wire insertion hole of the capillary in order to prevent bonding failure due to contamination in the capillary. In addition, ultrasonic vibration is applied to the capillary while the tip is immersed in the cleaning liquid.

Japanese Patent No. 4817341 JP-A-6-333773 Japanese Patent No. 34633043

  2. Description of the Related Art In recent years, in a wire bonding apparatus for bonding a part to be bonded using a copper wire, a silver wire, or the like, an inert gas supply nozzle for forming a ball in the inert gas of the copper wire, the silver wire, etc. is provided. . The inert gas supply nozzle is located between the capillary tip and the bonding surface, the distance from the capillary tip to the surface of the inert gas supply nozzle is short, and the space below the capillary is narrow. The inert gas supply nozzle has an opening through which the capillary passes during bonding.

  For this reason, when pulling out the wire from the capillary tip due to occurrence of wire breakage during wire bonding, the inert gas supply nozzle becomes an obstacle, and the wire bonding is started by pulling the wire laterally or obliquely from the capillary tip. I need to be prepared. When pulling out the wire from the capillary tip in the preparation stage for starting wire bonding, there is no restriction in the direction of pulling out the wire. When the contact is made, the wire is rubbed at the edge of the capillary, etc., and the wire is scratched or the wire is rubbed inside the capillary. The phenomenon of adhering to the tip of the capillary occurs. If these phenomena occur at the preparatory stage of the start of wire bonding, the generated wire debris may cause abnormal sparks, product contamination, and loop shape abnormalities during wire bonding execution, resulting in product defects and reducing manufacturing yield. There is a problem that.

  A skilled worker can pull out the wire from the tip of the capillary while avoiding contact with the inside edge of the capillary according to a rule of thumb, so there is no particular problem, but the operator who operates the wire bonding apparatus Includes inexperienced and inexperienced people. In particular, inexperienced workers are not familiar with the internal structure of the capillary, and the wire pulls to the side or obliquely below the edge of the capillary, so the wire and the edge of the capillary rub against each other. Therefore, there are problems such as generation of wire debris and disconnection of the wire without being smoothly drawn when the wire is drawn from the capillary. Moreover, even if it is an expert, when the wire is thinned or the life of the capillary is extended, there is a problem that the probability that the wire is disconnected at the tip of the capillary is increased when the wire is pulled out.

  As described above, in order to improve the manufacturing yield of the bonding apparatus, development of a mechanism for pulling out the wire from the tip of the capillary while avoiding contact with the inside edge of the capillary without depending on the skill level of the operator is required. It is desired.

  In addition, the dust generated from the wires not only lowers the production yield of the product for wire bonding, but also accumulates in a specific place due to air blowing from the wire bonding apparatus, indoor air conditioning, etc., and has an adverse effect. As a result, there is a problem that the frequency of maintenance of the wire bonding apparatus increases and the operating rate of the apparatus decreases.

  For this reason, while the wire is changing from a gold wire to a non-gold wire, it has not been a problem in the conventional wire bonding using a gold wire, in the wire bonding using an inert gas of a non-gold wire. It has become prominent as a defect.

  Further, although a wire guide is disclosed in Patent Document 2, the wire guide of Patent Document 2 is limited to a function as a relay jig for sending a wire to which a tension force is applied toward a capillary, It does not have a function for reducing the occurrence of damage to the wire when the wire is pulled out from the capillary in the preparation stage for starting wire bonding.

  Therefore, according to the present invention, when pulling out the wire from the capillary tip in the preparatory stage of starting wire bonding, the direction of pulling out the wire from the tip of the capillary is regulated, so that polishing scraps are generated from the wire due to contact with the capillary. An object of the present invention is to provide a wire feeding mechanism in a wire bonding apparatus in which occurrence of breakage or wire breakage is reduced.

  In order to achieve the above object, a wire feeding mechanism in a wire bonding apparatus according to the present invention includes a capillary having a through-hole penetrating in the vertical direction formed therein, and is installed below the capillary and is inserted into the through-hole. And a wire guide that regulates a drawing direction of the wire drawn from the lower end of the capillary so as not to contact the chamfer surface in the capillary.

  Further, the wire feeding mechanism in the wire bonding apparatus according to the present invention is characterized in that the drawing direction of the wire is set within a range less than an angle formed by a central axis of the through hole and a chamfer surface in the capillary. To do.

  Further, the wire guide of the wire feeding mechanism in the wire bonding apparatus according to the present invention includes a direction changing portion that changes a direction in which the wire drawn in the drawing direction extends.

  Further, the direction changing portion of the wire guide of the wire feeding mechanism in the wire bonding apparatus according to the present invention has a winding surface on which the central axis is arranged along the central axis of the through hole and the wire can be wound. The wire has a winding member, and the wire drawn in the drawing direction is wound around the winding surface from one side or the other side around the central axis of the winding member. It is characterized by conversion.

  Further, the wire guide direction changing portion of the wire feeding mechanism in the wire bonding apparatus according to the present invention is arranged so that a central axis is different from a direction of the central axis of the through hole, and the winding capable of winding the wire A winding member having a surface is provided, and the wire is redirected by winding the wire drawn in the drawing direction around the winding surface around a central axis of the winding member. .

  Further, the wire feeding mechanism in the wire bonding apparatus according to the present invention is provided with an inert gas supply device for supplying an inert gas to the wire drawn from the capillary between the capillary and the component to be bonded. A wire feeding mechanism in a wire bonding apparatus, wherein the wire guide changes the direction of the wire drawn in the drawing direction so as not to contact the inert gas supply device.

  According to the present invention, by providing the wire guide at the lower part of the capillary tip, when pulling out the wire from the capillary tip in the preparation stage of starting wire bonding, the direction of drawing the wire from the capillary tip can be regulated, The contact of the wire with the capillary can be reduced without depending on the skill level of the person. As a result, it is possible to reduce the occurrence of wire debris sticking to the tip of the capillary or wire breakage at the preparatory stage for starting wire bonding, and wire bonding execution caused by wire debris or wire breakage, etc. In addition to preventing abnormal sparks, product contamination, and loop shape abnormalities, the production yield of the wire bonding apparatus can be improved, and the operating rate of the wire bonding apparatus can be improved. Furthermore, a mechanism for cleaning the capillary of the wire bonding apparatus disclosed in Patent Document 3 can reduce contact between the wire and the inner surface of the capillary at the preparatory stage of the start of wire bonding to prevent contamination of the inner surface of the capillary. There is no need to provide it.

  According to the present invention, the work procedure is clarified by providing the wire guide at the lower part of the capillary tip, and the variation in the wire drawing work of the operator can be reduced. Can be maintained.

  According to the present invention, even if an inert gas supply device for preventing oxidation is provided between the capillary tip and the bonding surface and the space at the lower end of the capillary is narrowed, from the capillary tip in the preparation stage for starting wire bonding. When pulling out the wire, the direction in which the wire is pulled out from the tip of the capillary is regulated, so that the contact of the wire with the capillary due to the presence of the inert gas supply device is reduced regardless of the skill level of the operator. can do.

It is a block diagram which shows the structure of a wire bonding apparatus. (A) is a perspective view which shows the structure around a capillary in the wire bonding apparatus in which the wire guide is provided in the inert gas supply apparatus, (b) is the front view. (A) is a perspective view which shows the state which pulled out the wire from the capillary tip using a wire guide, (b) is the front view. It is sectional drawing which shows the inside of a capillary along the central axis (axial center) of the longitudinal direction of a capillary. It is a figure explaining the state of the wire pulled out from the capillary tip. It is a figure explaining the state of the wire pulled out from the capillary tip. (A) And (b) is a figure explaining the angle which the wire makes from the tip of a capillary in the position of a wire guide. It is the top view comprised so that the wire guide part of the wire guide provided in the side surface of the inert gas supply apparatus might follow the X-axis of an XY stage. (A) is a perspective view showing a configuration in which an L-shaped wire guide is used and a direction changing portion is attached so as to be parallel to the X axis of the XY stage, and (b) is a view from the capillary through the wire guide. It is a front view which shows the state which pulled out the wire. (A) is a perspective view which shows the structure which attached the wire guide which consists of a disk-shaped upper part and the truncated cone provided in the lower part of the disk, (b) is the drawing of the wire in the wire guide in the case of right-handed The front view which shows an example, (c) is a front view which shows the example of pulling out the wire in the wire guide in the case of left-handed. It is a figure explaining the vertical movement of the capillary tip. (A) is provided with a wire guide on the surface of the work clamp of the work transfer unit, and (b) is provided with a wire guide at a place other than the work clamp of the work transfer unit. It is a figure which shows the wire guide formed in the ring shape. It is a flowchart which shows a wire drawing-out procedure when the wire has come out of the capillary in the preparation stage for starting wire bonding.

  The best mode for carrying out a wire feeding mechanism in a wire bonding apparatus according to the present invention will be described below with reference to the drawings. The wire feeding mechanism in the wire bonding apparatus of the present invention provides a wire guide at the lower part of the capillary tip, thereby restricting the direction in which the wire is drawn from the capillary tip at the wire bonding start preparation stage. , Pulling the wire away from the direction of contact with the edge of the chamfer surface in the capillary, reducing the variation in the wire drawing work without depending on the skill level of the operator in the preparation stage of starting wire bonding, By eliminating sliding with the capillary, the occurrence of wire scraps or wire breakage is prevented. Details of the edge of the chamfer surface will be described later.

  In the following description, a wire bonding apparatus using a non-gold wire or the like will be described as a bonding apparatus.

  First, the configuration of the wire bonding apparatus will be described with reference to FIG. FIG. 1 is a block diagram showing the configuration of the wire bonding apparatus.

  FIG. 1 is a diagram showing a configuration of a wire bonding apparatus of the present invention. As shown in FIG. 1, a wire bonding apparatus 1 includes a bonding head 3 having a bonding tool such as a capillary, and an XY stage as a positioning unit that mounts the bonding head 3 and moves it two-dimensionally in the XY directions. 18, a bonding stage 20 for mounting a bonding target component such as a lead frame 44 on which an IC chip 45 or the like is mounted, and performing a bonding operation with a capillary 6 as a bonding tool, a control unit 30 including a computer (CPU) 31, It comprises a drive unit 39 that issues a drive signal to each motor of the bonding head 3 and the XY stage 18 in response to a command signal from the position control circuit 37.

  Note that the bonding stage 20 includes a work clamp that holds the component to be bonded and a transfer device (work transfer unit) that transfers the component to be bonded. The bonding head 3 includes an ultrasonic horn 5 having a capillary 6 as a bonding tool equipped with an ultrasonic vibrator and attached to the tip, and an ultrasonic horn 5 at one tip, and the other via a support shaft 9. A bonding arm 4 coupled to the movable part of the linear motor 10, an encoder 11 as a position detecting means for detecting the position of the capillary 6 attached to the tip of the ultrasonic horn 5, and a support shaft 9 of the bonding arm 4 And a linear motor 10 that swings in the vertical direction as a center.

  Further, as shown in FIG. 1, the bonding head 3 holds a wire 40 by an opening / closing mechanism during wire bonding, and a clamp 7 fixed to the ultrasonic horn 5 and moving up and down in conjunction with the capillary 6. I have. In addition, a wire 40 extending in the vertical direction is held via the capillary 6 and the clamp 7, and an air tension 8 is provided on the clamp 7.

  The air tension 8 blows air upward during wire bonding and operates to pull up the wire 40 so as to apply tension to the wire 40 and loosen the wire 40 between the capillary 6 and the clamp 7. Operates to lose.

  In place of the air tension 8, a second clamp as a gripping means may be provided. Unlike the clamp 7, the second clamp is fixed to the bonding head 3 without interlocking with the capillary 6.

  Further, the bonding head 3 is provided with a wire supply mechanism for supplying a wire. As shown in FIG. 1, the wire supply mechanism 12 includes a wire spool 13 around which a wire 40 is wound, a feed motor 14 that rotates the wire spool 13 to feed out the wire 40, and the wire 40 that has been fed out to the air tension 8. And a wire supply guide 15 for guiding.

  The clamp 7 is interlocked with the vertical movement of the bonding arm 4 during execution of wire bonding, and sandwiches or releases the wire 40 by an opening / closing mechanism (not shown), and is controlled by the control unit 30. . The wire 40 passes through the clamp surface of the opening / closing mechanism of the clamp 7, passes through a hole provided in the capillary 6, and is fed out from the tip of the capillary 6.

  Further, an inert gas supply device 50 that forms balls in an antioxidant gas atmosphere formed of an inert gas is provided below the capillary 6. The inert gas supply device 50 has an opening 53 (shown in FIG. 2A) through which the tip of the capillary 6 can pass. The inert gas supply device 50 has a built-in spark rod (not shown), and is high between the tip of the wire 40 fed from the capillary 6 and the spark rod built in the inert gas supply device 50. A spark discharge is caused by applying a voltage, the tip of the wire 40 is melted by the discharge energy, and a ball is formed at the tip of the wire 40 fed out from the capillary 6.

  Further, the wire bonding apparatus 1 includes an ultrasonic oscillator (not shown), applies a voltage to a vibrator incorporated in the ultrasonic horn 5, and a capillary 6 positioned at the tip of the ultrasonic horn 5. And generating ultrasonic vibration to the capillary 6 in response to a control signal from the control unit 30.

  The wire bonding apparatus 1 shown in FIG. 1 connects the pads on the semiconductor chip 45 and the leads of the lead frame 44 with wires 40 while heating the lead frame 44 such as a substrate. The connection of the wire 40 with a pad or a lead is performed by applying ultrasonic vibration and a load to the capillary 6 as a bonding tool.

  The capillary 6 positioned at the tip of the ultrasonic horn 5 of the bonding head 3 is configured to be movable in the XY axis by the XY stage 18 and in the vertical direction by the bonding head 3, that is, the position on the Z axis. The position of the capillary 6 attached to the tip of the ultrasonic horn 5 is detected by an encoder 11 that detects the rotation angle of the support shaft 9 of the bonding arm 4.

  As shown in FIG. 1, the wire bonding apparatus 1 has a wire guide 60 as a wire feeding mechanism for pulling out the wire 40 from the tip of the capillary 6 when a wire breakage or the like occurs during wire bonding. Yes.

  The wire guide 60 of the wire feeding mechanism in the wire bonding apparatus according to the present invention will be described below with reference to FIGS. FIG. 2A is a perspective view showing the configuration around the capillary in the wire bonding apparatus in which the wire guide 60 is provided in the inert gas supply apparatus 50, and FIG. 2B is a front view thereof. FIG. 3A is a view showing a state in which a wire is pulled out from the tip of the capillary using the wire guide 60, and FIG. 3B is a front view thereof.

  The wire guide 60 in the wire feeding mechanism shown in FIG. 2 is used when the wire 40 is pulled out from the tip of the capillary 6 which is a bonding tool attached to the tip of the ultrasonic horn 5 in the preparation stage for starting wire bonding. This is a jig that regulates the direction in which the wire 40 is pulled out from the wire. For example, preparation for starting wire bonding including a stage for resuming wire bonding due to wire breakage or the like when replacing the wire spool 13 or during wire bonding. In the stage, it is used when the wire 40 is continuously pulled out from the tip of the capillary 6 with its pulling direction regulated. As described above, the preparation stage for starting wire bonding includes an initial preparation stage for starting wire bonding, a stage in which the wire is disconnected during execution of wire bonding, and another wire bonding is started. . The meaning of the preparation stage for starting wire bonding to be used hereinafter is the same as described above.

  As shown in FIGS. 2A and 2B, the wire guide 60 in the wire feeding mechanism is provided on the side surface of the inert gas supply device 50 that blows an inert gas when forming a ball on the tip of the wire 40. Is provided. The wire guide 60 includes a wire guide portion 65 as a direction changing portion having a cylindrical shape, and a support fitting 70 that supports the wire guide portion 65 and is attached to the inert gas supply device 50. The wire guide portion 65 is attached along the surface of the inert gas supply device 50 that faces the capillary 6.

  The wire guide portion 65 having a cylindrical shape in the wire guide 60 has, for example, a cylindrical diameter of 1 to 2 mm and a length of about 3 mm, and is provided at a right angle to the flat plate of the support fitting 70. ing.

  The surface of the wire guide portion 65 that comes into contact with the wire 40 is processed into a mirror surface state, thereby reducing friction caused by contact with the wire 40 and sliding, and the wire 40 can be pulled out smoothly. Moreover, generation | occurrence | production of a wire flaw, generation | occurrence | production of wire scraps, generation | occurrence | production of a wire breakage, etc. can be prevented. The wire guide portion 65 includes a winding member having a winding surface around which the wire 40 can be wound, and the direction of the wire 40 can be changed by winding the wire guide portion 65 around the central axis of the winding member. .

  The support fitting 70 of the wire guide 60 has a plate shape, has a U-shaped cutout on the plate-shaped flat plate, and is screwed into the screw hole provided on the side surface of the inert gas supply device 50 via the cutout. It is fixed with.

  As described above, the inert gas supply device 50 is installed near the middle of the tip of the capillary 6 and the part to be bonded such as the lead frame 44, and has the opening 53 through which the tip of the capillary 6 can pass. Therefore, the wire guide 60 is attached at a position where the capillary 6 does not interfere with the vertical movement, for example, near the outer periphery of the inert gas supply device 50.

  Further, in order to prevent the occurrence of scraping of the wire 40 due to contact with the edge of the chamfer surface 6a (shown in FIG. 4) of the capillary 6 or the occurrence of disconnection of the wire 40, the wire 40 is pulled out to be a wire guide. The wire guide 60 is provided so that the wire 40 does not touch the chamfer surface 6 a provided inside the tip of the capillary 6 when it is hung on the tip 60. This is because the wire 40 comes into contact with the end surface of the chamfer surface 6a or the end edge of the chamfer surface 6a to reduce the generation of scraping of the wire 40 or the disconnection of the wire 40. The details of the contact of the wire 40 with the edge (ring-shaped corner) of the chamfer surface 6a when the wire 40 touches the chamfer surface 6a will be described later.

  As shown in FIGS. 3A and 3B, the wire 40 drawn from the tip of the capillary 6 is drawn in a direction close to the vertical, and the drawn wire 40 serves as a direction changing portion of the wire guide 60. From the side of the wire guide portion 65, it contacts the lower surface side of the wire guide portion 65 and is pulled out horizontally or below the wire guide portion 65.

  Further, the wire guide portion 65 of the wire guide 60 as a wire feeding mechanism has a function of a direction changing portion that changes the wire 40 from a state close to the vertical between the capillary 6 and the wire guide 60 to the lateral direction of the wire guide 60.

  An inert gas supply device 50 is provided in the space between the lower surface of the capillary 6 and the component to be bonded. Since the space from the lower surface of the capillary 6 to the inert gas supply device 50 is narrow, the wire guide 60 should be used. Thus, the wire 40 can be pulled out in a direction that reduces the contact with the capillary 6. Details regarding the attachment position of the wire guide 60 will be described later.

  Moreover, the structure of the wire bonding apparatus shown in FIG.1 and FIG.2 shows a general structure, and this invention is not limited to this.

  Hereinafter, the inside of the capillary through which the wire passes and the state in which the wire of the capillary is pulled out will be described with reference to FIGS.

  FIG. 4 is a cross-sectional view showing the inside of the capillary along the central axis in the longitudinal direction of the capillary. 5 and 6 are diagrams for explaining the state of the wire drawn from the tip of the capillary at the preparation stage for starting wire bonding.

  First, the shape of the capillary used for wire bonding will be described. As shown in FIG. 4, the capillary 6 has a through-hole penetrating in the vertical direction for passing the wire 40. The through hole has a space in the shape of a hole 6c and a substantially truncated cone (hereinafter referred to as a truncated cone) that extends downward from the hole 6c. The frustoconical space is a space that contributes to wire bonding using a ball formed at the tip of the wire 40. The diameter of the upper surface of the frustoconical space is the hole diameter H, and the inner end of the bottom 6b. Is indicated by a chamfer diameter CD, and a chamfer surface 6a is formed around a space having a truncated cone shape. The angle formed by the chamfer surface 6a is referred to as a chamfer angle and is denoted as θc. An angle θd formed by the chamfer surface 6a with respect to a central axis (also referred to as an axis or a central axis) in the longitudinal direction of the capillary 6 is θc / 2.

  The chamfer surface 6a of the truncated cone space is formed continuously with the hole 6c of the capillary 6, and the chamfer diameter CD, which is the diameter of the ring-shaped chamfer surface 6a, is larger than the hole diameter H of the hole 6c. Therefore, the lower end of the hole 6c and the edge 6e on the upper side of the chamfer surface 6a are continuous at an angle, and the continuous portion between the edge 6e of the chamfer surface 6a and the hole 6c is a ring-shaped sharp edge. Has a corner. Similarly, the lower edge 6d of the chamfer surface 6a and the bottom 6b of the capillary 6 are continuous at an angle, and the continuous portion of the edge 6d of the chamfer surface 6a and the bottom 6b of the capillary 6 is It has a ring-shaped sharp corner.

  Since the internal structure of the capillary 6 is the above-described structure, there is a high possibility that the wire 40 inserted through the hole 6c of the capillary 6 contacts the chamfer surface 6a or contacts the edges 6d and 6e of the chamfer surface 6a. It is. Due to these contacts, scraps or the like are generated from the wire 40 or the wire 40 is disconnected without being smoothly pulled out from the capillary. This situation is solved by the present invention. The structure will be described in detail below.

  FIG. 5 is a diagram for explaining the state of the wire drawn from the capillary tip in the preparation stage for starting wire bonding. As shown in FIG. 5A, when the wire 40 is fed out from the tip of the capillary 6 along the central axis, and as shown in FIG. 5B, the wire 40 from the tip of the capillary 6 is axial. When the angle θ1 formed with respect to the core is less than θd shown in FIG. 4, the wire 40 is pulled out without touching the chamfer surface 6 a and the lower surface of the capillary 6.

  On the other hand, as shown in FIG. 6A, the angle θ2 formed by the wire 40 drawn from the tip of the capillary 6 in the preparation stage for starting wire bonding is close to 90 degrees with respect to the axis of the capillary 6, and FIG. When it exceeds the indicated θd, the wire 40 is in contact with the edges 6d, 6e, etc. of the chamfer surface 6a inside the capillary 6. Further, as shown in FIG. 6B, when the angle θ3 formed by the wire 40 exceeds the angle θd shown in FIG. 4, the wire 40 rubs against the chamfer surface 6a inside the capillary 6. Moving. For this reason, the wire 40 is rubbed, and there is a possibility that wire scraps or wire breakage may occur.

  Furthermore, as shown in FIG. 6A, when the angle θ2 formed by the wire 40 from the tip of the capillary 6 is drawn at an angle of 90 degrees close to the horizontal state at the preparation stage for starting wire bonding, The wire 40 may be disconnected at the end edge while generating scraps. The generated cutting scraps may fall on the part to be bonded.

  Further, the tip shape of the capillary 6 has various shapes, sizes, and angles in order to improve bonding properties. For example, when the tip is formed at an acute angle, the wire is used in the preparation stage for starting wire bonding. When pulling 40 to the side of the capillary 6 or the like, the surface of the wire 40 may be damaged.

  In this way, when the wire 40 is pulled out at the preparation stage for starting wire bonding, the wire 40 is pulled in the pulling direction so as not to touch the chamfer surface 6a or the edges 6d and 6e provided inside the tip of the capillary 6. The guide 60 needs to be provided.

  Based on the above consideration, in the present invention, as shown in FIG. 5B, the wire 40 inserted into the hole 6 c of the capillary 6 is connected to the central axis of the capillary 6 (particularly the hole 6 c) and the chamfer surface 6 a of the capillary 6. The wire 40 is pulled out from the capillary 6 by setting the pulling direction of the wire 40 in a range less than the angle formed by the wire guide 60 and using the wire guide 60.

  The chamfer surface 6a may be formed in an arc shape in addition to the taper shape (linear shape). Accordingly, the angle formed between the central axis of the capillary 6 and the chamfer surface 6a of the capillary 6 is the angle formed between the linear chamfer surface 6a and the central axis of the capillary 6 in the case of the tapered chamfer surface 6a. Is applicable. In the case of the arc-shaped chamfer surface 6a, an angle formed by a line connecting at least the edges 6d and 6e of the chamfer surface 6a and the central axis of the capillary 6 is applicable.

  As shown in FIGS. 1 and 2, the inert gas supply device 50 is provided in the bonding head 3 and performs the same movement as the capillary 6 with respect to the movement of the XY stage 18. For this reason, the distance and direction between the two points of the wire guide 60 and the tip of the capillary 6 depend on the attachment position of the wire guide 60 and the position of the tip of the capillary 6 in the Z direction (shown in FIG. 2A).

  Next, the angle formed by the wire from the tip of the capillary 6 at the position of the wire guide 60 will be described with reference to FIG. FIG. 7A and FIG. 7B are views for explaining the angle formed by the wire from the tip of the capillary at the position of the wire guide 60.

  In the following description, it is assumed that the wire guide 60 is provided on the side surface or the surface of the inert gas supply device 50. The capillary 6 is assumed to be in a vertical state with respect to the horizontal plane.

  The wire guide 60 that holds the wire 40 drawn from the tip of the capillary 6 is held at the shortest distance between the tip of the capillary 6 and the wire guide 60 so that the wire 40 drawn from the tip of the capillary 6 is held. It is provided in the vicinity below the capillary 6 in the vertical direction.

  As shown in FIG. 7A, the distance L1 from the tip of the capillary 6 to the surface of the inert gas supply device 50 is 5 mm, and the wire guide 60 has a distance L2 in the vertical direction from the surface of the inert gas supply device 50. Contact the wire 40 at the position P1. At this time, the distance L2 is set to 1.5 mm. Further, the distance L3 between the axis of the capillary 6 and the position P1 of the wire guide 60 on the surface of the inert gas supply device 50 in plan view is 3 mm. A perpendicular perpendicular to the horizontal plane of the bonding apparatus (through the central axis of the capillary 6) is defined as a vertical line Lv.

  The angle θ4 formed by the wire 40 from the tip of the capillary 6 shown in FIG. 7A and the wire guide 60 is about 45 degrees with respect to the perpendicular Lv.

  In the case of such a positional relationship between the capillary 6 and the wire guide 60, it is recommended to use the capillary 6 with the chamfer angle θc shown in FIG. 4 exceeding 90 degrees.

  7B, the distance L1 from the tip of the capillary 6 to the surface of the inert gas supply device 50 is 5 mm, and the wire guide 60 is a distance from the surface of the inert gas supply device 50 in the vertical direction. The wire 40 is brought into contact with the position P2 of L2. At this time, the distance L2 is set to 1.0 mm. The distance L3 between the vertical line (axial center) Lv of the capillary 6 and the position P2 of the wire guide 60 on the surface of the inert gas supply device 50 in plan view is 3 mm. An angle θ5 formed by the wire 40 from the tip of the capillary 6 and the wire guide 60 is about 40 degrees with respect to the vertical line Lv.

  In the case of the positional relationship between the capillary 6 and the wire guide 60 shown in FIG. 7B, it is recommended to use the capillary 6 with the chamfer angle θc shown in FIG. 4 exceeding 80 degrees.

  As described above, when the angle formed by the wire 40 drawn from the tip of the capillary 6 in the preparatory stage for starting wire bonding is equal to or larger than θd shown in FIG. 4, the wire 40 contacts the chamfer surface 6 a inside the capillary 6. To do. For this reason, the wire guide 60 is provided at a position where it does not touch the surface and end edge of the chamfer surface 6a provided inside the tip of the capillary 6, or has a chamfer angle exceeding θd shown in FIG. It is recommended to select one of the following.

  In addition, the inert gas supply device 50 normally rotates with respect to the X axis so that the distal end portion is located on the capillary 6 side and the rear side is located on the XY stage 18 side with respect to the longitudinal direction in plan view. Installed in position. Since the wire guide 60 shown in FIG. 2 is provided on the side surface of the inert gas supply device 50, the wire guide portion 65 is not parallel to the X axis. For this reason, when pulling out the wire 40 from the wire guide 60, it is performed with a slight angle with respect to the front side.

  Next, another configuration of the wire guide 60 in which the wire guide 60 is provided on the side surface of the inert gas supply device 50 will be described with reference to FIG. FIG. 8 is a top view in which the wire guide portion 65 of the wire guide 60 provided on the side surface of the inert gas supply device 50 is configured to be parallel to the X axis of the XY stage.

  As shown in FIG. 8, the inert gas supply device 50 is rotated with respect to the X axis so that the tip is located on the capillary 6 side and the back side is located on the XY stage 18 side with respect to the longitudinal direction. Installed in position. At this time, the attachment angle with respect to the X axis in the longitudinal direction of the inert gas supply device 50 in plan view is defined as θ6. At this time, by setting the angle θ7 of the wire guide portion 66 as the direction changing portion to (180−θ6) degrees on the flat plate of the support fitting 70 attached to the side surface of the inert gas supply device 50, the direction changing portion indicated by the dotted line is obtained. The longitudinal axis of the wire guide portion 65 can be set to be perpendicular to the Y axis of the wire bonding apparatus. Thereby, the wire 40 can be pulled out from the wire guide 60 almost straight forward. Note that the angle θ7 of the wire guide portion 65 in the wire guide 60 provided on the side surface of the inert gas supply device 50 is not limited to an angle parallel to the X axis of the XY stage 18, but is another angle. Also good.

  Next, a configuration in which the wire guide 61 has an L shape and is provided on the surface of the inert gas supply device 50 will be described with reference to FIG. FIG. 9A is a perspective view showing a configuration in which a wire guide portion 67 as a direction changing portion is attached using an L-shaped wire guide 61 so as to be parallel to the X axis of the XY stage 18. (B) is a front view showing a state in which the wire 40 is pulled out from the capillary via the wire guide 61.

  A hole for attaching the wire guide 61 is provided on the surface of the inert gas supply device 50. As shown in FIG. 9, the surface of the inert gas supply device 50 is formed using the L-shaped wire guide 61. Are attached so that the wire guide portion 67 as the direction changing portion is parallel to the X axis of the XY stage. Thereby, since the wire guide part 67 is parallel to the X axis, the wire 40 can be pulled out before the bonding apparatus.

  Normally, the inert gas supply device 50 is installed at a position rotated with respect to the X axis so that the tip end is located on the capillary 6 side and the back side is located on the XY stage side in the longitudinal direction. As shown in FIG. 9, the L-shaped wire guide 61 is placed in a round hole on the surface of the inert gas supply device 50, and the wire guide portion 67 as a direction changing portion is parallel to the X axis of the XY stage 18. By attaching, the wire 40 can always be pulled out to a predetermined position of the bonding apparatus without being influenced by the attachment angle of the inert gas supply apparatus 50 to the bonding head.

In the preparatory stage for starting wire bonding, the operator pulls the wire 40 from the capillary 6 using tweezers or the like. Even if the worker is either right-handed or left-handed, the same state is maintained. A wire guide 62 as a wire feeding mechanism capable of performing work will be described with reference to FIG.
FIG. 10A is a perspective view showing a configuration in which a wire guide 62 composed of a disk-shaped upper part and a truncated cone provided at the lower part of the disk is attached.

  As shown in FIG. 10, the wire guide portion 68 as the direction changing portion of the wire guide 62 is composed of a disc-shaped upper portion and a truncated cone provided at the lower portion of the center of the disc, and is provided at the lower portion of the truncated cone. The lower part of the cylinder is a support metal fitting 70. The support fitting 70 of the wire guide 62 is inserted into the attachment hole of the inert gas supply device 50 and fixed. Thereby, the left and right shapes from the central axis of the wire guide 60 are the same, and even when the operator is either right-handed or left-handed, the wire can be pulled out and used in either the left or right direction. . 10B is a front view showing an example in which the wire 40 in the wire guide 62 is pulled out counterclockwise, and FIG. 10C is a front view showing an example in which the wire 40 in the wire guide 62 is pulled out clockwise. is there. Note that the wire guide portion 68 (the same applies to the wire guide portions 66 and 67 already described) includes a winding member having a winding surface around which the wire 40 can be wound, and the winding surface is centered on the central axis of the winding member. By winding, the direction of the wire 40 can be changed.

  As described in the description of FIG. 1, the bonding head 3 has an ultrasonic horn 5 with a capillary 6 attached to the tip, an ultrasonic horn 5 on one tip, and the other is a linear motor via a support shaft 9. It has a bonding arm 4 coupled to 10 movable parts. Next, the vertical movement of the tip of the capillary 6 accompanying the movement of the linear motor 10 will be described with reference to FIG. FIG. 11 is a diagram illustrating the vertical movement of the capillary tip.

  The linear motor 10 swings the bonding arm 4 in the vertical direction with the support shaft 9 as a fulcrum. For this reason, during execution of wire bonding, the capillary 6 performs an arc motion about the support shaft 9 as a central axis. At the time of bonding, the capillary 6 is set to be perpendicular to the bonding surface. On the other hand, when wire breakage or the like occurs, the work of pulling out the wire 40 from the tip of the capillary 6 is performed, but the work is performed at the highest point by raising the capillary 6.

  As shown in FIG. 11, the position of the highest point at the tip of the capillary 6 is on the arc Rc, and the central axis of the capillary 6 is a tangent Lc of the arc Rc. At this time, the angle θ8 with respect to the vertical line (perpendicular line) Lv of the capillary 6 is inclined by 7 degrees, for example. For this reason, pulling the wire 40 forward at the highest position of the capillary 6 is equivalent to an increase in the chamfer angle of the capillary 6 by 7 degrees, and the selection range of the capillary is expanded. Accordingly, it is desirable to move the capillary 6 to the highest point position and pull the wire 40 forward. Furthermore, it is preferable that the wire guide 60 is provided so as to be positioned on the front side of the front with respect to the position of the capillary 6.

  As described above, the wire feeding mechanism in the wire bonding apparatus according to the present invention includes the capillary in which the through hole penetrating in the vertical direction is formed, and the lower end of the capillary that is installed below the capillary and is inserted into the through hole. A wire guide that regulates the direction in which the wire drawn out from the wire does not contact the edge of the chamfer surface of the capillary.

  The wire guide 60 is a direction in which the wire is drawn out so that the wire drawn from the tip of the capillary 6 is held at the shortest distance between the tip of the capillary 6 and the wire guide 60 in the preparation stage of starting wire bonding. And is installed in the vicinity of the vertically lower side of the capillary 6.

  The bonding apparatus using the inert gas supply device 50 for forming a ball of a non-gold wire such as a copper wire in an inert gas atmosphere has been described above. Next, a wire using a gold wire (gold wire) is described. The wire guides 63 and 64 of the wire feeding mechanism in the bonding apparatus will be described. In bonding using a gold wire, an inert gas for preventing oxidation is not used, so that the inert gas supply device 50 is not necessary. However, in the preparatory stage of starting wire bonding, there is a possibility that an operator unaccustomed to the operation may pull out the wire 40 from the tip of the capillary 6 right next to the wire pull-out operation from the tip of the capillary 6 due to wire breakage. .

  12 and 13 are perspective views showing a configuration in which wire guides 63 and 64 as wire feeding mechanisms are provided in a wire bonding apparatus using a gold wire. The discharge electrode 17 shown in FIGS. 12 and 13 is provided between the capillary and the bonding surface.

  FIG. 12 shows the wire guide 63 provided on the workpiece conveyance unit (bonding stage) 20, and FIG. 12A shows the wire guide 63 provided on the surface of the workpiece clamp 21 of the workpiece conveyance unit 20. FIG. 12B shows the wire guide 63 provided at a location 22 other than the workpiece clamp 21 of the workpiece conveyance unit 20. At this time, the wire guide 63 is in a fixed position unlike the one provided in the inert gas supply device 50. For this reason, the capillary 6 is moved to the vicinity of the top of the wire guide 63 by the XY stage 18.

  FIG. 12B shows a wire guide 63 provided in a location 22 other than the work clamp 21 of the work transport unit 20. The wire guide 63 is different from that provided in the inert gas supply device 50 and is a bonding component. The position is fixed during clamping. For this reason, the XY stage 18 is moved near the top of the wire guide 63. Further, the work clamp 21 is raised when the clamp of the bonding component is released. Further, the wire 40 can be fed out while the work clamp 21 is raised and stopped.

  FIG. 13 is a diagram showing a configuration in which the wire guide 64 is formed in a ring shape. As shown in FIG. 13, the wire guide 64 includes, for example, a wire guide portion 69 as a ring-shaped direction changing portion. Use with a fixed rod. Further, the wire guide portion 69 as a ring-shaped direction changing portion may be positioned at the tip of the capillary 6 when necessary with a movable lever or the like, and may be fixed at another position during bonding.

  By forming the wire guide 64 in a ring shape, the wire can be pulled out from almost the entire circumference of 360 degrees on the circumference of the wire guide portion 69 as the direction changing portion. The wire guide portion 69 includes a winding member having a winding surface around which the wire 40 can be wound, and the wire 40 can change the direction by being wound around the winding surface of the winding member.

  As for the size, shape, installation position, etc. of the wire guide, first, there should be a guide in the vertical direction as much as possible when pulling out the wire, and second, there should be no interference with other parts. Thirdly, it is determined in consideration of not hindering the workability of wire handling.

  Next, in the preparatory stage for starting the wire bonding, the wire feeding procedure when the wire is pulled out of the capillary due to wire breakage or the like will be described with reference to the flowchart shown in FIG. FIG. 14 is a flowchart showing a wire drawing procedure when the wire has come out of the capillary.

  As shown in FIG. 14, in the preparatory stage for starting wire bonding, if the wire 40 is pulled out of the capillary 6 due to wire breakage or the like, the wire 40 is passed through the air tension 8 and the wire feeder as necessary (step S1). ). Next, the wire 40 is sandwiched between the cut clamps, and the tip of the wire 40 is cut with tweezers or the like (step S2). This is for removing curl and the like at the tip of the wire 40.

  A new tip of the disconnected wire 40 is pinched with tweezers so that the wire 40 is passed through the capillary 6 (step S3). After passing the wire 40 through the capillary 6, the wire 40 coming out from the tip of the capillary 6 is grasped and pulled out with the cut clamp opened (step S4). However, if the wire 40 is pulled out to the side at this time, the wire 40 is cut by the edge of the chamfer surface of the capillary, etc., so that the wire 40 is pulled out from the capillary 6 and pulled close to the wire guide 60. Like that. The wire 40 is hooked on the wire guide 60, and the wire 40 is pulled out along the wire guide 60. (Step S5).

  Next, when a transition is made from the wire bonding start preparation stage to the wire bonding execution stage, in order to form a ball at the tip of the wire 40, the wire bonding apparatus discards the bonding (step S6). By performing the abandoned bonding, a wire having a predetermined length is drawn out from the tip of the capillary 6, and a spark is discharged by the spark rod to form a ball. Thereby, a wire bonding operation can be started.

  As described above, according to the present invention, by providing the wire guide at the lower part of the capillary tip, in the preparation stage for starting wire bonding, the wire is supported by the wire guide and the direction in which the wire is drawn out is clarified. By reducing the variation in the wire drawing work of the operator in the preparatory stage for starting the wire and eliminating the sliding between the wire and the end of the capillary, the surface of the wire is damaged, the wire is damaged at the tip of the capillary, or the wire is broken. Etc. can be prevented.

  According to the present invention, by providing the wire guide at the lower part of the capillary tip, the work procedure becomes clear, and it is possible to reduce the variation in the wire drawing work of the worker in the preparation stage for starting the wire bonding. The procedure makes it possible to maintain the quality of the parts to be bonded.

  According to the present invention, even if an inert gas supply device for preventing oxidation is provided between the capillary tip and the bonding surface and the space at the lower end of the capillary is narrowed, from the capillary tip in the preparation stage for starting wire bonding. When pulling out the wire, the direction in which the wire is pulled out from the tip of the capillary is regulated. Contact can be reduced.

  The present invention can be embodied in many forms without departing from its essential characteristics. Therefore, it is needless to say that the above-described embodiment is exclusively for description and does not limit the present invention.

DESCRIPTION OF SYMBOLS 1 Wire bonding apparatus 3 Bonding head 4 Bonding arm 5 Ultrasonic horn 6 Bonding tool (capillary)
6a Chamfer surface 6b Bottom 6c Hole 6d, 6e Edge 7 Clamp 8 Error tension 9 Support shaft 10 Linear motor 11 Encoder 12 Wire supply mechanism 13 Wire spool 14 Feed motor 15 Wire supply guide 17 Discharge electrode (spark rod)
18 XY stage 20 Bonding stage (work transfer part)
21 Work clamp
22 Location other than work clamp 30 Control unit 31 Computer 37 Position control circuit 39 Drive unit 40 Wire 41 Ball 44 Substrate (lead frame)
45 Semiconductor (IC) Chip 50 Inert Gas Supply Device 53 Opening 60, 61, 62, 63 Wire Guide 65, 66, 67, 68, 69 Wire Guide (Direction Changer)
70 Support bracket

Claims (6)

A capillary in which a through-hole penetrating in the up-down direction is formed, and a chamfer surface in the capillary that is installed below the capillary and is drawn through the through-hole and drawn from the lower end of the capillary A wire guide that regulates in a direction not to contact
A wire feeding mechanism in a wire bonding apparatus characterized by comprising:   2. A wire feeding mechanism in a wire bonding apparatus according to claim 1, wherein the drawing direction of the wire is set to a range less than an angle formed by a central axis of the through hole and a chamfer surface in the capillary.   The wire feeding mechanism in the wire bonding apparatus according to claim 1, wherein the wire guide includes a direction changing portion that changes a direction in which the wire drawn in the drawing direction extends. The direction changing portion of the wire guide has a winding member having a winding surface on which a central axis is arranged along the central axis of the through-hole and the wire can be wound.
The wire is turned around by winding the wire drawn in the drawing direction from one side or the other side around the central axis of the winding member to the winding surface. Item 4. A wire feeding mechanism in the wire bonding apparatus according to Item 3. The direction changing portion of the wire guide has a winding member that is arranged so that a central axis is different from a direction of the central axis of the through-hole, and has a winding surface on which the wire can be wound,
The wire in the wire bonding apparatus according to claim 3, wherein the wire is redirected by winding the wire drawn in the drawing direction around the winding surface around a central axis of the winding member. Feeding mechanism. A wire feeding mechanism in a wire bonding apparatus provided with an inert gas supply device for supplying an inert gas to the wire drawn from the capillary between the capillary and a part to be bonded;
The wire bonding according to any one of claims 1 to 5, wherein the wire guide changes the direction of the wire drawn in the drawing direction so as not to contact the inert gas supply device. Wire feeding mechanism in the apparatus.

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