JP2003273150A - Wire bonding method and apparatus - Google Patents

Abstract

(57) [Problem] To provide a good connection between bonding points with wires, and to enable the production of a high-quality semiconductor. In connecting a wire 2 between an electrode 52 and a lead 53 by moving the capillary 1, after connecting the wire 2 to the electrode 52, the capillary 1 is moved in the direction of the lead 53 while forming a loop. After passing over the bonding point, the capillary 1 on the electrode 52 side
The wire 2 is connected to the bonding point on the lead 53 after the operation of pulling back is performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire bonding method and apparatus for connecting a first bonding point and a second bonding point with a wire.

[0002]

2. Description of the Related Art A wire bonding technique is known as a technique for electrically connecting an electrode provided on a semiconductor pellet and a lead formed on a lead frame by using a conductive wire.

An example of this technique will be described with reference to FIG.
It is as follows. First, a capillary (not shown) holding the wire 50 is vertically lowered from a position above the electrode 52 of the semiconductor pellet 51. When the capillary reaches a search level set at a predetermined height above the electrode, its descending speed is switched to a search speed slower than the existing speed, and the wire 50 is brought into contact with the electrode 52 while maintaining this speed.
Then, a predetermined bonding load and ultrasonic vibration are applied to the wire 50 via the capillary to bond (connect) one end of the wire 50 to the electrode.

Next, after raising the capillary by a predetermined amount,
It is moved above the lead 53 so as to draw a loop. When the capillary reaches the search level set at a predetermined height above the lead during this loop formation, the descending speed is switched to the search speed, and the wire 50 is brought into contact with the lead 53 while maintaining this speed. Then, a predetermined bonding load and ultrasonic vibration are applied to the wire 50 via the capillary to bond the wire 50 to the lead 53. And finally, the lead 53 of the wire 50
The connection part with and is disconnected, and one cycle is completed.

[0005]

In the wire bonding described above, the lead 53 of the wire 50 is used.
At the time of connection to the wire, as shown in FIG. 4, the capillary is usually moved so that the wire 50 is folded back at the position of the apex 54 of the loop, and then bonded to the lead 53.

However, especially when the semiconductor pellet 51 becomes large, the distance from the electrode 52 to the pellet end 51a is long, and the distance from the pellet end 51a to the bonding point on the lead 53 is short, the wire 50 is There is a risk of coming into contact with the pellet end portion 51a, and if it comes into contact, the quality as a semiconductor will be impaired.

In order to prevent this, it has been attempted to add a bulge between the apex 54 of the loop and the lead 53. However, in this case, the loop may collapse due to vibration during the lead frame transportation to the next process and the adjacent wires may come into contact with each other, or the bulge may be collapsed due to resin loading during molding. Yes, there is still no effective solution.

It is an object of the present invention to provide a wire bonding method and apparatus capable of satisfactorily connecting between bonding points with wires and capable of manufacturing a good quality semiconductor.

[0009]

A wire bonding method according to the present invention is a wire bonding method for connecting a first bonding point and a second bonding point with a wire by moving a capillary, after connecting the wire to the first bonding point. , Connecting the wire to the second bonding point after moving the capillary toward the second bonding point while forming a loop, moving the capillary too far above the second bonding point, and then pulling back the capillary to the first bonding point side It is characterized by doing.

The wire bonding apparatus according to the present invention is a wire bonding apparatus having a capillary, a moving device for the capillary, and a controller for the moving device. After connecting, the wire moves in the direction of the second bonding point while forming a loop, goes over the second bonding point and then returns to the first bonding point side, and then connects the wire to the second bonding point. The moving device is controlled so as to do so.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a front view of a wire bonding apparatus to which the present invention is applied, FIG. 2 is a view showing a movement path of a capillary using the wire bonding apparatus of FIG. 1, and FIG. 3 is a wire of FIG. It is a figure which shows the locus | trajectory of the movement of the wire using a bonding device. In each drawing, the same parts as those in FIG. 4 are designated by the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 1, the wire bonding apparatus 10 has a table 11 that moves in the XY directions and a bonding head 12 placed on this table 11. A supporting block 13 is provided on the bonding head 12, and a swing shaft 15 and a bonding arm 16 are swingably supported by a support shaft 14 provided on the supporting block 13. The capillary 1 having an insertion hole for the wire 2 is attached to one swing end of the bonding arm 16, and an ultrasonic transducer (not shown) is attached to the other end.

Further, a spring 17 and a voice coil motor 18 are arranged adjacent to each other between the rear portion of the bonding arm 16 and the swing block 15. Each end of the spring 17 is supported by the oscillating block 15 and the bonding arm 16, and urges the bonding arm 16 to the oscillating block 15 counterclockwise about the support shaft 14. The swing is performed by the stopper 1 provided on the swing block 15.
Limited by 9. On the other hand, the voice coil motor 18
The main body 18a is attached to the swing block 15, and the operating shaft 18b is attached to the bonding arm 16, respectively.
The voice coil motor 18 generates a pressing force corresponding to the current value at the rear portion of the bonding arm 16 by applying a current. Therefore, the biasing force of the spring 17 acting between the swing block 15 and the bonding arm 16 can be adjusted by adjusting the current applied to the voice coil motor 18.

In the figure, reference numeral 20 denotes a gap sensor provided on the swing block 15, and the gap sensor is provided so that its detection surface faces the other end of the bonding arm 16, and the bonding arm 16 is relative to the swing block 15. Detect the amount of movement.

A pair of support arms 21 are provided on the rear portion of the swing block 15 so as to project therefrom. An engaging pin 24 protruding from an eccentric position of the disk 23 rotated by the motor 22 is engaged between the pair of support arms 21, and an engaging pin centered on the output shaft of the motor 22. The swing block 15 is swung in accordance with the rotation direction and the rotation speed of 24. The swing amount of the swing block 15 is detected by an encoder (not shown) connected to the motor 22. Also,
The detection values of the encoder and the gap sensor 20 are sent to the control device 30.
Based on these signals, 0 controls the operation of the table 11, the voice coil motor 18, and the motor 22 as described later. A clamper (not shown) is provided in the path of the wire 2 held by the capillary 1, and the wire 2 is appropriately released and held by the opening / closing operation of the clamper.

Next, the bonding operation of the wire bonding apparatus 10 will be described.

First, by moving the table 11, the capillary 1 is moved to a position A above the electrode 52 of the semiconductor pellet 51.
The ball is formed at the tip of the wire due to the discharge between the tip of the wire and the torch electrode (not shown) (see FIG. 2). Next, the motor 22 is driven, and the bonding arm 16 swings together with the swing block 15 with the rear end of the bonding arm 16 contacting the stopper 19, and the capillary 1
Begins to descend. At this time, the clamper is opened,
The wire is paid out. And at the time of this descent, the motor 22
The capillary 1 is connected to an encoder (not shown).
Is detected to have reached the search level, the controller 30 reduces the rotation speed of the motor 22 and reduces the descending speed of the capillary 1 to the search speed. And capillary 1
The wire 2 held on the electrode 52 of the semiconductor pellet 51.
When the contact is made with the contact, the detection value of the gap sensor 20 changes with the contact, so the control device 30 regards this change time as the contact timing, and a predetermined bonding load and ultrasonic vibration are applied to the wire 2 contacting the electrode 52. And the wire 2 is bonded to the electrode 52. Here, the bonding load is the difference between the urging force of the spring 17 and the pressing force of the voice coil motor 18 according to the applied current. The ultrasonic vibration is generated by an ultrasonic vibrator (not shown) provided at the other end of the bonding arm 16.

When the bonding to the electrode 52 is completed in this way, the capillary 1 is moved up to the position B by the distance a by the rotation of the motor 22, and then the table 11 is moved to the position away from the lead 53 by the distance b. Move horizontally to C. Thereafter, the capillary 1 moves up from the position C to the position D by the distance c, then moves horizontally in the direction opposite to the lead 53 by the distance d to the position E, and moves up the distance e to the position F. When the capillary 1 reaches the position F, the capillary (not shown) is closed and holds the wire 2. In this state, the horizontal movement of the table 11 and the downward movement of the capillary 1 by the rotation of the motor 22 are performed in parallel, Capillary 1
Moves toward the bonding point on the lead 53 while forming a loop.

Now, the capillary 1 which moves while forming a loop passes above the bonding point on the lead 53 and is at the G position, that is, at the same level as the search start level set above the lead 53, and the lead 53. It moves from the above bonding point to a position away from the semiconductor pellet 51 by a distance f.

Here, in the present embodiment, when the capillary 1 reaches the position G, the current applied to the voice coil motor 18 is increased and a pressing force close to the biasing force of the spring 17 is applied to the rear portion of the bonding arm 16. It is given to.

After the capillary 1 reaches the G position, the descending speed is reduced to the search speed, and the table 11 and the motor 22 are driven so that the capillary 1 descends obliquely toward the bonding point on the lead 53. To do.
It should be noted that the locus of movement during the downward movement is preferably a gradient that gently intersects the horizontal plane. During this downward movement, the gap sensor 20 detects the relative movement between the swing block 15 and the bonding arm 16 to detect that the wire 2 is in contact with the bonding point on the lead 53. At this time, as described above, since the pressing force close to the biasing force of the spring 17 is applied to the rear portion of the bonding arm 16 by the voice coil motor 18, when the wire 2 contacts the bonding point on the lead 53. A weaker pressing force than the regular bonding load applied at the time of bonding to the lead 53 is applied to the wire 2.

Next, from this state, the table 11 is moved by a slight distance in the direction away from the electrode 52 and stopped. Then, when stopped, the current applied to the voice coil motor 18 is controlled to release or weaken the pressing force on the bonding arm 16. As a result, a regular bonding load by the spring 17 is applied to the wire 2 via the capillary 1. Then, ultrasonic waves are applied from an ultrasonic vibrator (not shown), and the wires 2 are bonded to the bonding points on the leads 53.

When the bonding to the lead 53 is completed, the clamper (not shown) is opened, and the capillary 1 is
The wire 2 is lifted up to the tip of the capillary 1 for the length required for the next ball formation. Here, the clamper is closed, and the clamper in the closed state moves up together with the capillary 1. As a result, the wire 2 is cut at the connecting portion with the lead 53, and one cycle is completed.

FIG. 3 shows a forming state and a movement locus of the wire 2 formed by the movement locus of the capillary 1. In FIGS. 2 and 3, the same reference numerals indicating the distance indicate corresponding portions. Show.

As shown in FIG. 3, due to the movement of the capillary 1 described above, the overall shape of the wire loop formed between the bonding of the electrode 52 and the lead 53 becomes trapezoidal, and the distance h rises from the electrode 52 by a distance h. The upper bottom has a shape bonded to the bonding point on the lead 53 with a hypotenuse of distance j and distance e.

In the embodiment described above, the movement of the capillary 1 is such that, after the wire 2 is bonded on the electrode 52, it passes above the bonding point on the lead 53 while forming a loop, and then the G position, that is, the lead. 53
Of the semiconductor pellet 5 at the same level as the search start level set above the
The wire 2 is bonded to the bonding point on the lead 53 by moving it to a position away from the position 1 by a distance f, and then pulling it back toward the semiconductor pellet 51, that is, toward the electrode 52 side. Therefore, immediately before the wire 2 is bonded to the bonding point on the lead 53, the loop formed between the electrode 52 and the lead 53 is applied with a force that lifts the entire loop upward. become. Therefore, even if the size of the semiconductor pellet 51 is increased, the distance from the electrode 52 to the pellet end portion 51a is long, and the distance from the pellet end portion 51a to the bonding point on the lead 53 is short, the wire 2 that has conventionally occurred. Is the end 5 of the pellet
It is possible to prevent contact with 1a and improve the quality of the semiconductor.

Further, just before the wire 2 is bonded to the bonding point on the lead 53, the capillary 1 is pulled back so that the formed loop has a strong angle habit with respect to the wire 2. For this reason, the same effect as above can be obtained.

In the above embodiment, an example in which the electrode 52 and the lead 53 are bonded to each other has been described. However, the application of the present invention is to wire-bond the leads to each other and the electrodes to each other. It is applicable even if there is.

Further, the case where the capillaries are moved and controlled so that the loop shape becomes a trapezoid has been described, but it is also possible to form a type of loop called a normal triangular loop shown in FIG. It is not specific to the loop shape.

[0031]

As described above, according to the present invention,
Wires can be satisfactorily connected between the bonding points, and a good quality semiconductor can be manufactured.

[Brief description of drawings]

FIG. 1 is a front view of a wire bonding apparatus to which the present invention is applied.

FIG. 2 is a diagram showing a movement path of a capillary using the wire bonding apparatus of FIG.

FIG. 3 is a diagram showing a locus of movement of a wire using the wire bonding apparatus of FIG.

FIG. 4 is a view showing a connection state of wires formed by a conventional technique.

[Explanation of symbols]

1 capillary 2 wires 11 table 12 Bonding head 13 Support block 14 spindle 15 swing block 16 Bonding arm 17 spring 18 voice coil motor 20 Gap sensor 21 Support arm 22 motor 23 discs 30 control device 50 wires 51 Semiconductor pellet 51a pellet end 52 electrodes 53 lead

Claims (2)

[Claims] 1. A wire bonding method for connecting a wire between a first bonding point and a second bonding point by moving a capillary, wherein a wire is connected to the first bonding point and then a loop is formed in the direction of the second bonding point. Move the capillary,
A wire bonding method characterized in that, after passing over the second bonding point, the capillary is pulled back to the first bonding point side, and then the wire is connected to the second bonding point. 2. A wire bonding apparatus comprising a capillary, a moving device for the capillary, and a control device for the moving device, wherein the control device forms a loop after the capillary connects the wire to a first bonding point. And moving toward the second bonding point, moving past the second bonding point too much, and then returning to the first bonding point side, and thereafter controlling the moving device to connect the wire to the second bonding point. A wire bonding apparatus characterized by: