Bonding apparatus and alignment method

Abstract

Provided is a positioning method for aligning the positions of a horn and a clamper of a bonding device.　This bonding device (1) comprises: a clamper (17) that can clamp a wire (2) between paired arms (17L, 17R); a horn (16) in which a first through hole (41) capable of holding a capillary (15) as well as a second through hole adjacent to the first through hole and penetrating the horn (16) in the vertical direction are formed; and a bonding stage (20) on which a work can be mounted. This positioning method for aligning the positions of the horn and the clamper of the bonding device comprises: so disposing a mirror surface (200) as to be parallel to the bonding stage; positioning a mirror image (420) of the second through hole reflected in the mirror surface to the center of the second through hole when the mirror surface is seen through the second through hole; and positioning the clamper on the basis of the positions of the mirror image and the horn.

Description

Technical Field

[0001] The present invention relates to an alignment method for aligning the positions of a horn and a clamper of a bonding apparatus.

Background Art

[0002] A bonding apparatus is used in the post-process of semiconductor manufacturing to connect the electrodes of an IC chip and a lead frame with a metal wire. The bonding apparatus includes a capillary for thermocompression bonding of the wire using ultrasonic waves, a horn for applying ultrasonic waves to the capillary, and a clamper for gripping the wire supplied to the capillary (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The clamper is arranged to grip the wire on the axis of the capillary. Since wires such as gold wires used for bonding are soft, they are easily damaged. If the center of the clamper is displaced from the axis of the capillary, the clamper or the capillary may rub against the wire, causing damage to the surface of the wire. Since the capillary is held by the horn, it is important to accurately align the clamper with respect to the horn. However, since accurate alignment takes time, the burden on the operator is large. In addition, since it depends on the skill level of the operator, there is a risk of variation in the positioning accuracy.

[0005] Therefore, an object of the present invention is to provide an alignment method capable of accurately aligning the position of the clamper with respect to the horn of a bonding apparatus.

Means for Solving the Problems

[0006] The alignment method according to one aspect of the present invention is an alignment method for aligning the positions of the horn and the clamper of a bonding apparatus. The bonding apparatus includes a clamper capable of clamping a wire between a pair of arms, a horn in which a second through-hole is further formed adjacent to the first through-hole capable of holding a bonding tool and penetrating the horn in the vertical direction, in addition to the first through-hole, and a bonding stage on which a workpiece can be placed. The alignment method includes arranging a mirror surface to be parallel to the bonding stage, aligning the mirror image of the second through-hole reflected on the mirror surface with the center of the second through-hole when viewing the mirror surface through the second through-hole, and aligning the clamper based on the positions of the mirror image and the horn.

[0007] A bonding apparatus according to another aspect of the present invention includes a clamper capable of clamping a wire between a pair of arms, a horn in which a second through-hole is further formed adjacent to the first through-hole capable of holding a bonding tool and penetrating the horn in the vertical direction, in addition to the first through-hole, a bonding stage on which a workpiece can be placed, and a control unit that performs alignment of the horn and the clamper. When the control unit views a mirror surface arranged to be parallel to the bonding stage through the second through-hole, the control unit aligns the mirror image of the second through-hole reflected on the mirror surface with the center of the second through-hole, and aligns the clamper based on the positions of the mirror image and the horn.

[0008] According to these aspects, in the direction perpendicular to the bonding stage, since the clamper is moved with the mirror image of the second through-hole reflected on the mirror surface aligned with the center of the second through-hole, the horn and the clamper can be accurately aligned.

[0009] In the above aspect, aligning the mirror image may include moving the viewpoint to a position where the mirror image of the second through-hole can be seen at the center of the second through-hole. Aligning the clamper may include moving the clamper so that the symmetry plane of the clamper, which is equidistant from each of the pair of arms, overlaps with the symmetry plane of the horn that bisects the first through-hole and the second through-hole when viewed from the viewpoint.

[0010] According to this aspect, in the direction perpendicular to the bonding stage, the mirror image of the second through-hole reflected on the mirror surface, the second through-hole, and the viewpoint from which they are viewed are aligned in a straight line. While maintaining this positional relationship, by moving the symmetry plane of the clamper so as to overlap with the symmetry plane of the horn, the horn and the clamper can be accurately aligned.

[0011] In the above aspect, the opening of the second through-hole has a teardrop shape with a vertex where the curvature is maximized, and aligning the clamper may include moving the clamper so that the symmetry plane of the clamper overlaps with the vertex when viewed from the viewpoint.

[0012] According to this aspect, since there is a vertex with a shape that is extremely curved and pointed, it is easier to visually recognize where the symmetry plane of the horn is compared to the case where the opening of the second through-hole is circular and has no vertex. Using the vertex as a mark, the horn and the clamper can be more accurately aligned.

Advantages of the Invention

[0013] According to the present invention, it is possible to provide an alignment method capable of accurately aligning the position of the clamper with respect to the horn of the bonding apparatus.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

DETAILED DESCRIPTION OF THE INVENTION

[0015] Preferred embodiments of the present invention will be described with reference to the accompanying drawings. In each figure, those denoted by the same reference numerals have the same or similar configurations. Hereinafter, the present invention will be described in detail with reference to the drawings.

[0016] One embodiment of the present invention is an alignment method for aligning the positions of the horn 16 and the clamper 17 of the bonding apparatus 1. FIG. 1 is a side view schematically showing the configuration of the bonding apparatus 1. In the illustrated example, the bonding apparatus 1 includes a base 11, an XY table 12, a bonding head 13, a torch electrode 14, a capillary 15, a horn 16, a clamper 17, a wire tensoner 18, a rotating spool 19, a bonding stage 20, a heater 21, a control unit 10, and the like.

[0017] In the following embodiments, a plane parallel to a semiconductor element or a lead frame to be bonded is defined as the XY plane, and a direction perpendicular to the XY plane is defined as the Z-axis direction. The Z-axis direction is the vertical direction. Note that the vertical direction is not strictly limited to the vertical direction and may be slightly inclined from the vertical direction. The tip position of the capillary 15 can be specified by spatial coordinates (X, Y, Z) represented by an X coordinate, a Y coordinate, and a Z coordinate.

[0018] The base 11 is configured by slidably mounting the XY table 12. The XY table 12 is a moving device capable of moving the capillary 15 to a predetermined position in the XY plane based on a drive signal from the control unit 10. The bonding head 13 is a moving device that holds the tip of the capillary 15 attached to the tip of the horn 16 so as to be movable in the Z-axis direction so that the tip approaches and separates from the surface of a workpiece such as a substrate based on a drive signal from the control unit 10.

[0019] The horn 16 is a rod-shaped member composed of a base end portion, a flange portion, a horn portion, and a tip portion from the base end to the tip. The base end portion is provided with an ultrasonic oscillator 22 that vibrates in response to a drive signal from the control unit 10. The flange portion is attached to the bonding head 13 so as to be resonant at a position that becomes a node of ultrasonic vibration. The horn portion is an arm that extends longer than the diameter of the base end portion and has a structure that amplifies the amplitude of the vibration by the ultrasonic oscillator 22 and transmits it to the tip portion. The tip portion is configured as a mounting portion that holds the capillary 15 in a replaceable manner. The tip portion of the horn 16 will be described in detail later with reference to FIGS. 2 to 6.

[0020] The horn 16 as a whole has a resonance structure that resonates with the vibration of the ultrasonic oscillator 22, and is configured such that the ultrasonic oscillator 22 and the flange portion are located at the nodes of the vibration during resonance, and the capillary 15 is located at the antinode of the vibration. With these configurations, the horn 16 functions as a transducer that converts an electrical drive signal into mechanical vibration.

[0021] The capillary 15 is an example of a bonding tool used for bonding. The capillary 15 is formed in a cylindrical shape, and the wire 2 used for bonding is inserted therethrough. The capillary 15 is attached to the tip portion of the horn 16 in a replaceable manner. The clamper 17 includes a pair of arms 17L and 17R that open and close based on a signal from the control unit 10, and can grip and release the wire 2 at an arbitrary timing.

[0022] The wire tensioneur 18 has the wire 2 inserted therethrough and can apply an appropriate tension to the wire 2 during bonding by freely changing the tension on the wire 2 based on the control signal from the control unit 10. The rotating spool 19 holds a reel around which the wire 2 is wound in a replaceable manner and is configured to pay out the wire 2 according to the tension applied from the wire tensioneur 18. Note that the material of the wire 2 is selected from ease of processing and low electrical resistance. Usually, gold (Au), silver (Ag), aluminum (Al), copper (Cu), or the like is used.

[0023] The torch electrode 14 is connected to a high-voltage power supply (not shown) via a discharge stabilizing resistor, generates a spark (discharge) based on a control signal from the control unit 10, and can form a free air ball at the hanging end of the wire 2 fed out from the tip of the capillary 15 by the heat of the spark. The bonding stage 20 is a processing table on which a semiconductor chip or a lead frame to be bonded can be placed. A heater 21 is embedded in the upper surface of the bonding stage 20 and is configured to heat the semiconductor chip or the lead frame to a temperature suitable for bonding. The upper surface of the bonding stage 20 is formed parallel to the XY plane described above.

[0024] The control unit 10 is configured to be able to output various control signals for controlling the bonding apparatus 1 based on a predetermined software program. The configuration of the bonding apparatus 1 is not limited to the illustrated example. For example, a moving device for moving in the X-axis direction and / or the Y-axis direction may be provided on the side of the bonding stage 20. Alternatively, moving devices may be provided on both the side of the XY table 12 and the side of the bonding stage 20.

[0025] FIG. 2 is a side view showing an example of the horn 16 and the clamper 17 shown in FIG. 1. As shown in FIG. 2, the horn 16 is arranged such that its longitudinal direction is along the horizontal direction.

[0026] FIG. 3 is a bottom view of the tip of the horn 16 shown in FIG. 2 as viewed from the lower side in the vertical direction. As shown in FIG. 3, a first through hole 41 and a second through hole 42 that penetrate the horn 16 are formed at the tip of the horn 16. The first through hole 41 is a holding hole for the capillary 15 and is formed in a circular shape following the outer shape of the capillary 15.

[0027] The second through hole 42 is adjacent to the first through hole 41. The second through hole 42 is formed in a teardrop shape having a vertex 421 where the curvature is maximized. The first through hole 41 and the second through hole 42 communicate with each other through a slit (narrow path portion) 43. The slit 43 is located on the side opposite to the vertex 421. The horn 16 is formed to be mirror-symmetrical with respect to a symmetry plane 160 that bisects the first through hole 41 and the second through hole 42. The symmetry plane 160 includes the center of the first through hole 41 and the vertex 421 of the second through hole 42.

[0028] Similarly, the clamper 17 is formed to be mirror-symmetrical with respect to a symmetry plane 170 of the clamper 17 that is equidistant from each of the gripping surfaces where the pair of arms 17L and 17R grip the wire 2. However, the clamper 17 is not limited to being mirror-symmetrical with respect to the symmetry plane 170, and the arrangement of members such as tightening screws may be different between the pair of clamp arms 17L and 17R.

[0029] Subsequently, with reference to FIGS. 4 to 6, the alignment method according to the present invention will be described. FIG. 4 is a flowchart showing an example of the alignment method according to the present invention. FIG. 5 is a plan view of the clamper 17 shown in FIG. 2 as viewed from the upper side in the vertical direction. FIG. 6 is a front view of the horn 16 and the clamper 17 shown in FIG. 2 as viewed from the tip side. In the alignment method according to the present invention, first, a mirror surface 20 is arranged so as to be parallel to the bonding stage 20 (step S1). The mirror surface 200 is not limited to the plane mirror shown in FIG. 6, and may be a plating film or the like processed on the bonding stage 20, including various things having the function of a mirror surface.

[0030] Subsequently, as shown in FIG. 5, when the mirror surface 200 is viewed through the second through hole 42, the mirror image of the second through hole reflected on the mirror surface 200 is aligned with the center of the second through hole (step S2). To align the mirror image 420, for example, the viewpoint 400 (shown in FIG. 6) may be moved to a position where the mirror image 420 can be seen at the center of the second through hole 42. Note that "view" and "visible" include not only visual observation but also capturing an object within the imaging range of a camera.

[0031] Then, as shown in FIG. 6, the alignment method according to the present invention aligns the clamp 17 based on the positions of the mirror image 420 and the horn 16 (step S3). To align the clamp 17, for example, when viewed from the viewpoint 400, the clamp may be moved so that the symmetry plane 170 of the clamp 17 overlaps the symmetry plane 160 of the horn 16.

[0032] The procedure of the alignment method described so far may be automatically executed by the control unit 10 or manually executed by an operator. When the control unit 10 executes the above-described procedure, the bonding apparatus 1 may further include an actuator for moving the clamp 17.

[0033] According to the alignment method of each embodiment of the present invention, as shown in FIG. 6, in the direction perpendicular to the bonding stage 20, the mirror image 420 of the second through hole 42 reflected on the mirror surface 200, the second through hole 42, and the viewpoint 400 for viewing them are aligned in a straight line. While maintaining this positional relationship, the symmetry plane 170 of the clamp 17 is moved so as to overlap the symmetry plane 160 of the horn 16, so that the horn 16 and the clamp 17 can be accurately aligned. Since the second through hole 42 has a teardrop shape, the horn 16 and the clamp 17 can be more accurately aligned using the vertex 421 as a mark.

[0034] The embodiments described above are for facilitating the understanding of the present invention and are not for limiting and interpreting the present invention. Each element included in the embodiments and its arrangement, material, conditions, shape, size, etc. are not limited to those exemplified and can be changed as appropriate. Also, it is possible to partially substitute or combine the configurations shown in different embodiments.

Description of Reference Numerals

[0035] 1... Bonding apparatus, 2... Wire, 10... Control unit, 11... Base, 12... XY table, 13... Bonding head, 14... Torch electrode, 15... Capillary (an example of a bonding tool), 16... Horn, 17... Clamp, 17L, 17R... Arms, 18... Wire tensiometer, 19... Rotating spool, 20... Bonding stage, 21... Heater, 22... Ultrasonic oscillator, 41... First through-hole, 42... Second through-hole, 43... Slit, 160... Symmetry plane of the horn, 170... Symmetry plane of the clamp, 200... Mirror surface, 400... Viewpoint, 420... Mirror image, 421... Vertex, X... Left-right direction, Y... Front-back direction, Z... Up-down direction.

Claims

1. An alignment method for aligning the positions of a horn and a clamper of a bonding apparatus, comprising: The bonding apparatus includes: The clamper capable of clamping a wire between a pair of arms; In addition to the first through hole capable of holding a bonding tool, the horn further formed with a second through hole adjacent to the first through hole and penetrating the horn in the vertical direction; A bonding stage on which a workpiece can be placed, and The alignment method includes: Arranging a mirror surface to be parallel to the bonding stage; When viewing the mirror surface through the second through hole, aligning the mirror image of the second through hole reflected on the mirror surface with the center of the second through hole, and Aligning the clamper based on the positions of the mirror image and the horn. Alignment method.

2. Aligning the mirror image includes moving the viewpoint to a position where the mirror image can be seen at the center of the second through hole, Aligning the clamper includes moving the clamper so that, when viewed from the viewpoint, the symmetry plane of the clamper that is equidistant from each of the pair of arms overlaps with the symmetry plane of the horn that bisects the first through hole and the second through hole. The alignment method according to Claim 1.

3. The opening of the second through hole has a teardrop shape with a vertex where the curvature is maximized, Aligning the clamper includes moving the clamper so that, when viewed from the viewpoint, the symmetry plane of the clamper overlaps with the vertex. The alignment method according to Claim 2.

4. A clamper capable of clamping a wire between a pair of arms; In addition to the first through hole capable of holding a bonding tool, a horn further formed with a second through hole adjacent to the first through hole and penetrating the horn in the vertical direction; A bonding stage on which a workpiece can be placed; and A control unit for performing alignment between the horn and the clamper, The control unit: When viewing a mirror surface arranged to be parallel to the bonding stage through the second through hole, aligns the mirror image of the second through hole reflected on the mirror surface with the center of the second through hole, Aligns the clamper based on the positions of the mirror image and the horn. Bonding apparatus.

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