JP2000260805A - Wire bonder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable stable bonding by making the direction of the stitch coincide with the oscillating direction of an ultrasonic wave, whatever direction of the oscillating direction may become. SOLUTION: This bonder comprises capillaries 3 for passing bonding wires to be thermocompression-bonded, which are provided at the top ends of horns connected to ultrasonic oscillators V. A pair of horns 11, 12 are provided in the capillaries perpendicular to their axial lengths and disposed with spacings in the length direction of the capillaries.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire bonding apparatus and, more particularly, to a wire bonding apparatus that bonds a bonding wire using ultrasonic vibration.

[0002]

2. Description of the Related Art An example of a conventional wire bonding apparatus for bonding a bonding wire using ultrasonic vibration is shown in FIGS. The wire bonding apparatus includes an ultrasonic vibrator V, a horn 1 attached to the ultrasonic vibrator V and amplifying the vibration, and a bonding wire 9 attached to a tip of the horn 1.
(See FIG. 7) and a capillary 3 for applying vibration to the bonding wire 9 and thermocompression bonding to the stitch 8. In such a wire bonding apparatus, the vibration applied to the capillary 3 is limited to one direction as shown by a vibration direction 10 in FIGS.

[0003]

However, such a conventional wire bonding apparatus has the following problems to be improved. That is, the first problem is that in the case of the UNTC bonder using the Au wire,
As shown in FIG. 7B, when the longitudinal direction of the stitch 8 is orthogonal to the vibration direction 10, the crushed portion of the bonding wire 9 is electrically short-circuited with the adjacent stitch. The reason is that the Au wire bonder (UNT
In the case C), there is no rotating mechanism for rotating the work 7 so that the longitudinal direction of the stitch 8 matches the vibration direction of the horn 1. Therefore, in the Al wire bonder having the rotating mechanism, the above-described problem does not occur because the longitudinal direction of the stitch can be made to coincide with the vibration direction. In the case of the Au line as well, such a problem is eliminated when the longitudinal direction of the stitch 8 and the vibration direction are in a parallel position as shown in FIG. 7A. However,
In the case of the Au wire bonder, it is difficult to provide a rotating mechanism because it has a heating mechanism below the work and needs to transport a strip-shaped package such as a lead frame. The second problem is that if the vibration power is reduced to reduce the above problem, the stitch 8
And the bonding strength of the bonding wire 9 is weakened, and the bonding wire 9 is easily peeled off. The reason is that the bonding wire 9 pressed against the stitch 8 by the ultrasonic wave is insufficiently deformed, and a sufficient slip (dislocation on the surface of the bonding wire 9) cannot be generated. For the purpose of solving these problems, in the case of the current Au wire bonder, an XY stage driven by a ball screw is installed under the work 7 so as to be quasi (not ultrasonic) in the XY direction. Means for freely generating vibration are taken. However, due to the structure that mechanically converts rotational motion into linear motion, the frequency is on the order of several hundred Hz, and at the present time, the same level of bondability as ultrasonic waves cannot be obtained.

The present invention has been made in view of such a conventional problem, and realizes stable bonding by making the longitudinal direction of the stitch coincide with the vibration direction of the ultrasonic wave regardless of the direction. Aim.

[0005]

According to a first aspect of the present invention, a wire bonding apparatus is thermocompression-bonded to a tip of a horn connected to an ultrasonic vibrator to achieve the above-mentioned object. A wire bonding apparatus provided with a capillary for passing a bonding wire, wherein a pair of the horns are provided on the capillary so as to be orthogonal to each other in an axial direction thereof, and the pair of horns are provided with a length of the capillary. It is characterized by being provided at intervals in the direction. According to a second aspect of the present invention, in the wire bonding apparatus, one of the pair of horns according to the first aspect is used as a main horn, the other horn is used as a sub horn, and the main horn is used for the capillary. Is attached below the slave horn. According to a third aspect of the present invention, in the wire bonding apparatus, the main horn according to the second aspect is fixed to a position of one third of a total length of the capillary from a lower end of the capillary, and the slave horn is It is characterized in that the capillary is fixed at a position 1/3 of the total length of the capillary from the upper end. In the wire bonding apparatus according to claim 4 of the present invention, the main horn according to claim 2 is fixed at a position 1/3 of the entire length of the capillary from a lower end of the capillary, and the slave horn is From the upper end of the capillary,
It is characterized in that it is fixed at a position one fifth of the total length of the capillary. A wire bonding apparatus according to a fifth aspect of the present invention is characterized in that the vibration frequency of the main horn and the vibration frequency of the slave horn according to any one of the first to fourth aspects are matched. According to a sixth aspect of the present invention, there is provided a wire bonding apparatus wherein the vibration frequency of the main horn and the vibration frequency of the sub horn according to any one of the first to fourth aspects are different from each other. I do. Furthermore, the wire bonding apparatus according to claim 7 is characterized in that the vibration frequency of the main horn and the sub horn according to any one of claims 1 to 6 is set within a range of 60 kHz to 90 kHz. I do.

At the time of wire bonding, the vibrators of the orthogonal horns are independently vibrated and the power is individually changed, whereby the longitudinal direction of the stitch and the vibration direction can be matched.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. In the following description, portions common to FIGS. 6 and 7 are denoted by the same reference numerals, and description thereof will be simplified. As shown in FIG. 1, the wire bonding apparatus according to the present embodiment includes a main horn 11
And the secondary horn 12 are kept perpendicular to each other when viewed in the longitudinal direction of the capillary 3 (in a plan view), and the two capillary mounting holes are matched when viewed in a plan view (in the Z direction). 12, a single capillary 3 is attached, and each of the horns 11 and 12 is provided with an ultrasonic transducer V. FIG. 2A is a view of the slave horn 12 from the side, and FIG. 2B is a view of the master horn 11 from the side. The master horn 11 and the slave horn 12 with respect to the capillary 3 are shown. In the case of the main horn 11, the installation position is one-third of the total length of the capillary 3 from the lower end of the capillary 3, and in the case of the slave horn 12, one of the total length of the capillary 3 from the upper end of the capillary 3. / 3 are set respectively. The main horn 11, the sub horn 12, and both ultrasonic transducers V are mounted on a single bonding head 6.

Next, the operation of the present embodiment configured as described above will be described. In the state shown in FIG. 1, when each ultrasonic transducer V is vibrated, any of the ultrasonic transducers V
Also, the lower part of the capillary 3 (the junction of the bonding wire) and the horn 11.
The mounting portion 2 becomes the maximum amplitude point, and the power can be transmitted efficiently. The vibration frequency of each ultrasonic transducer V is 6
A range of 0 to 120 kHz is generally used, and when the frequencies of the main and sub ultrasonic transducers V are the same within the above range,
Alternatively, it is possible to appropriately change, for example, in the case of an ultrasonic transducer having a different frequency within this range,
An optimum frequency can be selected depending on a bonding material, a package material, and the like.

Then, both horns 1 for the capillary 3
The mounting positions 1 and 12 and the amount of displacement of the lower portion of the capillary 3 will be described. FIG. 3C illustrates a relationship between a mounting position of the horn 11 with respect to the capillary 3 and a displacement waveform (that is, a deformation amount of the bonding wire) at a lower portion of the capillary 3. The source is an excerpt from page 1877 of the Handbook of Ultrasound Technology (Nikkan Kogyo Co., Ltd .: 4th revised edition published on December 30, 1984). Here, the total length of the capillary 3 is 20.8 mm, and the vibration frequency of the ultrasonic vibrator V is 60 kHz. As shown in FIG.
Assuming that the distance from the lower end of the capillary 3 to the mounting position of the horn 11 (12) is 1, this distance 1 is 8 mm and 1
In the vicinity of 4 mm (mounting in the vicinity of the upper and lower 1/3 of the total length of the capillary 3), the deformation width becomes maximum, and l = 10.4 mm
(1/2 of the total length of the capillary 3) is minimum. This is because the displacement waveform 5 of the main horn 11 changes as shown in FIG.
A driving part (vibration applying part);
The position where the phase with the lower end of the capillary 3 (bonding portion of the bonding wire) coincides; the maximum is obtained at l = 8 mm and 14 mm, and the minimum is obtained at the position 1 = 10.8 mm where the phase is inverted.

Therefore, the mounting position of the main horn 11 is
The displacement of each of the horns 11 and 12 is set by setting the position of the subordinate horn 12 at a position 1/3 of the entire length from the upper end of the capillary 3 to the position 1/3 of the total length from the lower end of the capillary 3. 2 (a) and 2 (b)
, The horn 11.
2, the amplitude given to the lower end (tip) of the capillary 3 can be maximized. Moreover, the two horns 11 and 12 are provided orthogonal to each other, so that the capillary 3 can be subjected to two-dimensional vibration. By individually adjusting the driving force applied to both horns 11 and 12, the vibration direction of the capillary 3 can be changed, whereby the vibration direction of the capillary 3 easily matches the direction of the stitch 8. be able to. As a result, reliable wire bonding can be performed regardless of the direction of the stitch 8.

Next, regarding another embodiment of the present invention,
This will be described with reference to FIGS. In the present embodiment, the planar positional relationship between the main horn 11 and the sub horn 12 is the same as that in FIG. 5 (a) is a view of the slave horn 12 from the side, and FIG. 5 (b) is a view of the main horn 11 from the side. The main horn 11 is 1/1 of the total length of the capillary 3 from the lower end of the capillary 3. 3 position, and
A slave horn 12 is attached at a position １ ／ of the entire length of the capillary 3 from the upper end of the capillary 3.

In such a configuration, each horn 11 ・ 1
Looking at the displacement waveform 2, for example, in the case of the slave horn 12, a displacement waveform as indicated by reference numeral 4 in FIG.
Further, in the case of the main horn 11, a displacement waveform as indicated by reference numeral 5 in FIG. The maximum amplitude point in the displacement waveform 4, that is, the deformation waveform generated by the slave horn 12, is determined by the mounting portion between the slave horn 12 and the capillary 3,
And it occurs at the lower end of the capillary 3, and also occurs at the attachment portion between the main horn 11 and the capillary 3. That is, the driving of the slave horn 12 also causes the main horn 11 to vibrate, or the main horn 11
Therefore, attention must be paid to the bonding efficiency (similarly, when the main horn 11 is viewed from the slave horn 12, the same result is obtained). In this embodiment, the same operation and effect as those of the first embodiment can be obtained. In addition to this, in the present embodiment, the mounting positions of the main horn 11 and the sub horn 12 to the capillary 3 are set. Is asymmetrical, for example, when viewed from the slave horn 12 side, the mounting position of the main horn 11 with the capillary 3 is moved away from the maximum amplitude point of the displacement waveform of the slave horn 12 (rather, toward the constraint point side). By bringing them closer, an effect of preventing the vibrations of the horns from interfering with each other can be obtained. This is the same when viewed from the main horn side.

The various shapes and dimensions of the components shown in the above embodiments are merely examples, and can be variously changed based on the type and shape of a work (stitch) to be applied, design requirements, and the like. .

[0014]

As described above, the wire bonding apparatus according to the present invention has the following excellent effects. The first effect is that stable bonding (the crushing direction of the bonding wire at the time of bonding coincides with the longitudinal direction of the stitch) is possible regardless of the direction of the stitch in the longitudinal direction. Further, since there is no danger that the crushed portion of the bonding wire is short-circuited between the adjacent wires, fine pitch bonding becomes possible, and it is possible to easily increase the number of pins. The reason is that a pair of horns are spaced apart in the longitudinal direction of the capillary, and are provided perpendicular to each other when viewed from the axis of the capillary. And by changing the power individually,
This is because the vibration direction can be adjusted to an arbitrary direction. The second effect is that the XY stage under the work is not required, so that the weight can be reduced and the control system can be simplified. The reason is that the control system can be partially shared because a horn having a similar structure is used (the need for introducing a new controller for the XY stage is eliminated, and the rotation system, ie, mechanically The number of moving parts is reduced, so the size and weight can be reduced).

[Brief description of the drawings]

FIG. 1 is a plan view showing an embodiment of the present invention.

FIGS. 2A and 2B show one embodiment of the present invention, wherein FIG. 2A is a side view of a slave horn, and FIG. 2B is a side view of a main horn.

FIG. 3 is a diagram illustrating a function of an embodiment of the present invention.
FIG. 4 is a diagram illustrating a relationship between a mounting position of a horn on a capillary and a displacement waveform of the capillary.

FIG. 4 is a plan view showing another embodiment of the present invention.

5A and 5B show another embodiment of the present invention, wherein FIG. 5A is a side view of a slave horn, and FIG. 5B is a side view of a main horn.

FIG. 6 is a plan view showing a conventional example.

FIG. 7 is a schematic diagram showing a state of wire bonding for stitches along different directions.

[Explanation of symbols]

 V Ultrasonic transducer 1 Horn 3 Capillary 4 Displacement waveform (of main horn) 5 Displacement waveform of (sub horn) 6 Bonding head 7 Work 8 Stitch 9 Bonding wire 10 Vibration direction 11 Main horn 12 Sub horn

Claims (7)

[Claims] 1. A wire bonding apparatus comprising: a capillary for passing a bonding wire to be thermocompression-bonded to a tip of a horn connected to an ultrasonic vibrator;
A wire bonding apparatus, wherein a pair of the horns are provided on the capillary so as to be orthogonal to each other in the axial direction, and the pair of horns are provided at intervals in a length direction of the capillary. 2. The method according to claim 1, wherein one of the pair of horns is a main horn, the other horn is a sub horn, and the main horn is attached to the capillary below the sub horn. The wire bonding apparatus according to claim 1. 3. The main horn is fixed from a lower end of the capillary to a position which is one third of a total length of the capillary,
3. The wire bonding apparatus according to claim 2, wherein the slave horn is fixed at a position that is 全長 of a total length of the capillary from an upper end of the capillary. 4. 4. The main horn is fixed from the lower end of the capillary to a position which is one third of the total length of the capillary,
3. The wire bonding apparatus according to claim 2, wherein the slave horn is fixed from an upper end of the capillary to a position which is １ ／ of a total length of the capillary. 4. 5. The vibration frequency of the main horn and the vibration frequency of the sub horn are matched.
A wire bonding apparatus according to claim 4. 6. The vibration frequency of the main horn and the vibration frequency of the sub horn are made different.
A wire bonding apparatus according to claim 4. 7. The wire bonding apparatus according to claim 1, wherein the vibration frequencies of the main horn and the sub horn are set within a range of 60 kHz to 90 kHz.