JP3417752B2 - Bonding method and apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bonding method and apparatus applied to wire bonding and the like.

[0002]

2. Description of the Related Art FIG. 9 is a block diagram showing a wire bonding apparatus. A capillary 1 having a wire 2 penetrating therethrough is provided as a bonding tool at the tip of a horn 3 which vibrates ultrasonically. The ultrasonic horn 3 is installed at the other end of the rocking body 4, and the rocking body 4 is configured to rotate by a drive unit (linear motor) 6 about a fulcrum not shown. The oscillating body 4 and the driving unit 6 are installed on the XY table 20, and the XY table 2
By driving 0, the capillary 1 is moved onto the electrode 14A on the semiconductor element 14 arranged on the base 11. Reference numeral 21 is a rotary position detection sensor that detects the position of the capillary 1.

The wire bonding operation of the above device will be described. First, the capillary 1 suddenly descends, and when it comes to a predetermined position from the semiconductor element 14, the capillary 1 descends at a constant speed and collides with the electrode 14A of the semiconductor element 14. When the semiconductor element 14 collides, the amount of change in the position detected by the position detection sensor 21 becomes small. Therefore, a controller (not shown) determines that the landing has been made, a preset collision load is applied, and after a certain period of time, bonding is performed. Pressed instead of load. At the same time, ultrasonic vibration is applied by the horn 3 to bond the wire 2 to the semiconductor element 14. After that, the wire 2 is cut by a cutting machine (not shown),
A series of operations ends.

Conventional Example 1. 10 and 11 show the waveforms of the load according to the bonding control method described in JP-A-4-348046 (conventional example 1), where f is the collision when the capillary 1 collides with the semiconductor element 14. The load, which is determined by the inertia of the entire oscillating system (1, 3, 4, 6), the natural frequency, and the collision speed. Fa is a bonding load setting value, and Fs1 is a bonding load value represented by (f + Fa) / 2.

In the conventional example 1, the impact load f is calculated in advance, and the bonding load Fs1 between the collision load f and the load setting value Fa is calculated from the time when the capillary 1 descends and collides with the semiconductor element 14. For example, by controlling the value to (f + Fa) / 2, the fluctuation of the bonding load is reduced.

FIG. 10 shows the load change when the descending speed of the capillary 1 is fast and the collision load f is larger than the bonding load set value Fa, and FIG. 11 is the capillary 1
Shows a change in load when the falling speed is slow and the impact load f is smaller than the bonding load setting value Fa.

Conventional example 2. FIG. 12 shows another bonding control example (conventional example 2), in which the drive unit (linear motor) 6 is moved in synchronization with the downward pulse emitted from the position detection sensor 21 when the capillary 1 is lowered. Motor command (motor current)
To occur. Since the descending pulse is stopped at the time of landing, the motor command is changed to the impact load value Fs0 at that time, and the impact load value Fs0 is held for a certain period of time and then changed to the bonding load value Fa.

[0008]

The conventional bonding control method is configured as described above, and the load setting in both the conventional example 1 and the conventional example 2 is changed rectangularly and discontinuously. The fluctuation of the actual load at the time of bonding becomes large and the load is not stable. As a result, there is a problem that the bonding work becomes unstable.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a stable bonding method and apparatus with less load fluctuation.

[0010]

Means for Solving the Problems of claims 1 invention, Bonn
The landing tool was detected by moving the ding tool close to the welded part.
After that, the bonding load is changed to the impact load value Fs by a predetermined inclination α.
(Or α1) is used to change the slope and shock load value Fs
To the bonding load set value Fa from the predetermined slope β (or
In the bonding method that shifts the slope in β1),
From the tilt when pressing the bonding tool to the joined part,
Tilt when releasing the pressure from the bonding tool
It is characterized by a looser texture.

The invention of claim 2 is the same as the invention of claim 1.
The bonding load at an impact load value Fs at a predetermined time
It holds TFS for a while.

According to a third aspect of the present invention, there is provided a position detecting means (position detecting sensor 7) for detecting the position of the bonding tool with respect to the joined portion, and a load command pattern (pressing the bonding tool to the joined portion). The standard command F), the standard command correction unit that adds the amount of change in the bonding tool position detected by the position detection unit to the load command pattern, and generates the motor command, and the bonding tool landed on the bonded portion. After this is detected, a drive means for applying a bonding load in accordance with the load command pattern is provided.

According to a fourth aspect of the present invention, as the position detecting means,
A rising pulse A is generated when the bonding tool separates from the bonded portion, a falling pulse B is generated when the bonding tool approaches the bonded portion, and the bonding tool lands on the bonded portion when the falling pulse B does not occur for a predetermined time. It is a judgment.

According to the invention of claim 5, the bonding load is changed according to the load command pattern at a predetermined inclination α2 when the falling pulse B is not generated for a predetermined time, and when the next falling pulse is generated, the original load level is set to the predetermined level. It is returned with a slope β2.

According to a sixth aspect of the present invention , the predetermined slope β2 is made gentler than the predetermined slope α2.

According to the invention of claim 7, the inclination angles α and β at the time of transferring the bonding load and the signal level from the position detecting means added to the load command pattern can be parametrically changed. For example, during the holding time TFS of the collision load value Fs, the level pu of the rising pulse fed back to the reference command is reduced.

According to an eighth aspect of the present invention, means for previously obtaining the relationship between the collision speed Vs and the collision load f with respect to the bonded portion of the bonding tool, the collision load f, and the bonding load Fs.
Alternatively, it is provided with means for setting any one of the collision speeds Vs and means for generating a load command pattern so that the collision load f and the bonding load Fs become equal.

Further, in the invention of claim 9, after the bonding tool is brought close to the bonded portion and the landing is detected, the bonding load is set to the bonding load set value Fa at a predetermined inclination.
It was made to shift to the slope.

Further, in the invention of claim 10, position detecting means for detecting the position of the bonding tool with respect to the joined portion is provided, and the amount of change of the bonding tool position detected by the position detecting means is added to the load command pattern. I chose

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1. 1 is a block diagram showing a wire bonding apparatus according to Embodiment 1 of the present invention. In the drawing, a wire 2 is penetrated through a capillary 1 as a bonding tool, and this capillary 1 is arranged at one end of a horn 3 which vibrates ultrasonically. The ultrasonic horn 3 is installed at the other end of the rocking body 4, and the rocking body 4 is configured to rotate about a fulcrum 5 by a drive unit (linear motor) 6. The oscillating body 4 and the driving unit 6 are installed on an XY table (not shown), and by driving the XY table, the capillary 1 is moved to the electrodes on the semiconductor elements 14 and 15 arranged on the base 16. Let

Reference numeral 7 is a position detection sensor for measuring the vertical movement position of the oscillating body 4 to detect the height position of the capillary 1. In the present embodiment, a linear encoder type sensor which emits a predetermined pulse according to the vertical movement of the capillary 1 is used. You are using a position sensor. Then, the signal (pulse) taken in from the position detection sensor 7 is sent to the main control unit 8 including a CPU, a RAM, a ROM and the like. The main control unit 8 drives and controls the drive unit (linear motor) 6 through the motor drive circuit 9 and applies ultrasonic waves to the horn 3 via the ultrasonic transmitter 10.

A search speed setting unit 11, a collision load setting unit 12, and a bonding load setting unit 13 are connected to the main control unit 8. Of these, the search speed setting device 11 is for setting the descending speed of the capillary 1, the collision load setting device 12 is for setting the collision load when the capillary 1 collides, and the bonding load setting device 13 Is for setting the bonding load applied after the collision load. And these three
The two parameters are set by the user.

FIG. 2 is a signal diagram showing a method for controlling the bonding load according to this embodiment. In the figure,
(A) is a rising pulse signal detected by the position detection sensor 7 when the capillary 1 is rising, and has a pulse width t
u, pulse height pu. (B) is a falling pulse signal detected by the position detection sensor 7 when the capillary 1 descends, and has a pulse width t
d, with pulse height pd. The main controller 8 discriminates the rising or falling pulse sent from the position detection sensor 7. (C) is a motor command sent from the main control unit 8 to the motor drive circuit 9, which is an inverted signal of the rising pulse (A) and a falling pulse (B) based on a standard command (F) described later.
Is generated by adding. (D) is an actual load measured by a load meter during actual bonding. (E) is a signal line representing the detection of landing, and the main control unit 8 determines that the landing is performed if the falling pulse (B) does not occur for a certain period from the constant velocity descent. Incidentally, JP-A-4-34
As shown in Japanese Patent No. 8046, a method of directly detecting the contact between the capillary 1 and the semiconductor element 14 by providing a surface detection portion on the landing portion can be considered. (F) is a reference command, and after detecting landing by the descending pulse (B) from the constant velocity descending command of the capillary 1, the collision load value is gradually increased at a predetermined inclination α (0 ° <α angle <90 °). After shifting to Fs and holding TFS at the collision load value Fs for a certain period of time, inclination β (angle of 0 ° <β <90 °)
Is a load command signal for gradually changing to the bonding load set value Fa.

FIG. 3 is a control block diagram showing a load command and a motor command in the main controller 8. First, the descending speed Vs of the capillary 1 from the search speed setting device 11
The collision load value Fs when the capillary 1 collides with the semiconductor element or the like from the collision load setting device 12, the bonding load setting value F after the collision load from the bonding load setting device 13.
When a is respectively set, the main control unit 8 gradually increases from the predetermined load value Fp toward the collision load value Fs with an inclination α, holds the collision load value Fs for a fixed time TFS, and bonds with the inclination β. A standard command (F) for shifting to the load set value Fa is generated. On the other hand, the rising pulse (A) or the falling pulse (B) is discriminated from the signal transmitted from the position detection sensor 7 (linear encoder), and if the falling pulse (B) is not generated for a certain period of time, it is regarded as landing, and the above reference command ( F)
Is gradually increased to the collision load value Fs with an inclination α toward the collision load value Fs. In addition, the normal / reverse inversion value of the rising pulse (A) is added to the reference command (F), and the falling pulse (B) is added to generate the motor command (C). The motor command (C) is generated. The motor drive circuit 9 is controlled based on the above, and the drive unit (linear motor) 6 is driven.

Next, the bonding operation according to the first embodiment will be described. Capillary 1 is semiconductor device 1
The main controller 8 gives an instruction to the motor drive circuit 9 so as to descend at a constant speed from the upper surface of 4. During this constant velocity descent, as shown in FIG. 2B, the position detection sensor 7 issues descent pulses at regular intervals. Then, when the capillary 1 actually lands on the upper surface of the semiconductor element 14, the falling pulse interval is extended, and finally the falling pulse is not generated. If the falling pulse does not occur for a certain period of time, the main control unit 8 determines that the capillary 1 has landed at that time, and gradually raises the reference command (F) toward the collision load value Fs with the inclination α. . Then, after reaching the collision load value Fs, the collision load value Fs is maintained for a fixed time (TFS), and thereafter gradually shifts to the bonding load setting value Fa with an inclination β. While being pressed by the bonding load setting value Fa, ultrasonic vibration is applied to the capillary 1 by the horn 3, and the wire 2 is bonded to the electrode of the semiconductor element 14. During this series of operations,
The motor command (C) is a falling command (B) to the reference command (F).
And forward / reverse inversion values of the rising pulse (A), respectively, and sent to the motor driving unit 9 to drive the driving unit (linear motor) 6
To control. After that, the capillary 1 rises to bond the wire to the lead 15, the wire 2 is cut by a cutting machine (not shown), and the wire bonding work is completed.

As described above, according to the first embodiment, the following operation is achieved. (1). Since the landing is detected from the constant velocity descending command of the capillary 1, the collision load value Fs is gradually changed at the inclination α, and the bonding load setting value Fa is gradually changed at the inclination β. The load fluctuation during bonding is reduced, and stable operation is guaranteed. (2). By holding the impact load value Fs in the bonding load setting pattern for a predetermined time (TFS), the change in the bonding load can be further reduced. (3). When the inversion signal of the rising pulse is added to the reference command (F) to generate the motor command (C), when the capillary 1 rapidly rises during bonding, that is, when the load sharply decreases. In addition, the load can be increased according to the rising timing, and the decrease in the load can be suppressed. (4). By generating the motor command (C) by adding the falling pulse to the standard command (F), when the capillary 1 drastically descends as in (3), that is, the load sharply increases. In this case, the load can be reduced according to the descending timing, and the increase of the load can be suppressed.

Embodiment 2. In the first embodiment, the pulse width (time) (t) of the rising pulse or the falling pulse detected by the position detection sensor 7 (t
u, td), pulse height (level) (pu, pd), holding time TFS at the collision load value Fs of the standard command, inclination α when shifting to the collision load value Fs, and bonding load set value Fa. Although the slope β at this time is set in advance, it may be parametrically changeable. For example, the load becomes more stable in our experiments if the level pu of the rising pulse (A) fed back to the reference command (F) is reduced only for the holding time TFS of the collision load value Fs.

Embodiment 3. In the first embodiment, as an example of the standard command (F), the collision load value Fs is gradually increased with a predetermined inclination α,
Although the collision load value Fs is held at TFS for a certain period of time and then gradually lowered to the bonding load setting value Fa with the inclination β, it is also applied to other standard command modes. For example, when the collision load value Fs is set to be lower than the standard load Fp and the bonding load Fa, as shown in FIG.
1 (0 ° <α1 angle <90 °) Gradually collision load value F
s, and at a collision load value Fs for a certain time TFS1
After the holding, it may be gradually increased to the bonding load setting value Fa with the inclination β1 (angle of 0 ° <β1 <90 °).

Fourth Embodiment An ideal load applied by the user at the time of bonding generally has a load waveform as shown in FIG. That is, it is ideal that the actual impact load value f, the set impact load value Fs, and the bonding load setting value Fa are all equal (f = Fs = Fa). In the conventional example and the first embodiment, the parameters set by the user in order to obtain the load waveform as described above are the descending speed of the capillary (search speed Vs) set by the search speed setting device 11, and the collision load setting device 12. Collision load value Fs when colliding with the semiconductor element set from
It is the bonding load set value Fa after the collision load set by the bonding load setter 13, and there is a problem that it takes time to set the three parameters and set conditions. Therefore, the search speed (collision speed) Vs and the collision load f are measured in advance as shown in FIG. 6, and the search speed (collision speed) V is calculated from the correlation therebetween.
Let s be set automatically. Further, the actual impact load value f, the set impact load value Fs, and the bonding load set value Fa are equal (f = Fs = Fa). That is, in the example of FIG. 6, the measured collision load f and the collision speed V are measured.
Since the relation of s is Vs = 1 / 5f, if the bonding load Fa is set, the search speed Vs becomes Vs = 1 /
5Fa and the set collision load Fs are automatically set as Fs = Fa. Therefore, the number of parameters set by the user or the like can be reduced from three of the search speed Vs, the collision load value Fs, and the bonding load setting value Fa to, for example, one of the bonding load setting value Fa. Also, it does not take time to set the conditions.

Embodiment 5. In the above-mentioned embodiment, if the falling pulse does not occur for a certain period of time, the main control unit 8 judges that the landing is performed and shifts the reference command to the predetermined load value with a predetermined inclination, but when the capillary 1 descends at a constant speed. Even if the landing is not actually performed due to a disturbance or the like, the interval of the descending pulse is extended, so that the landing may be erroneously detected. Therefore, in the present embodiment, as shown in FIG. 7, when the capillary 1 descends at a constant speed, a disturbance occurs and the interval of the descending pulse (B) is extended, and as a result, the reference command (F) is generated.
Is gradually increased to the impact load value with the inclination α2, the reference command (F) is gradually returned to the predetermined level Fp with the inclination β2 when the next falling pulse P1 is generated. The motor command (C) is generated by adding the falling pulse (B) to the standard command (F) as in the above.
In this way, in the method of detecting landing by the falling pulse, the detection of landing will not be erroneous even if disturbance or the like occurs.

In FIG. 7, the magnitude | α2 | of the rising slope of the reference command (F) and the absolute value | β2 | of the falling slope returning to the original load level may be changed. In our experiment, the direction in which the absolute value | α2 | of the upward slope is made larger than the absolute value | β2 | of the downward slope, that is, the direction of releasing pressure from the direction of applying pressure to the semiconductor element of the capillary 1 The gentler control required less fluctuation in the load and improved the bonding work. This state is shown in FIGS. 8A and 8B.
(A) shows a case where the absolute value of the rising slope | α2 | is made equal to the absolute value of the falling slope | β2 | that returns to the original level, whereas the load fluctuation of the actual load increases. FIG. 8B shows the case where | α2 | is made larger than | β2 |, and it can be seen that the fluctuation of the actual load is small.

Further, similarly to the above, Embodiments 1, 3, 4
In the above, it was found that if the inclination of the bonding load when releasing the pressure from the bonded portion of the capillary 1 is made gentler than the inclination of the bonding load when the capillary 1 is pressed against the bonded portion, the fluctuation of the load is small. .

Other Embodiments. In the above embodiment, the one applied to the wire bonding is described, but the inner lead bonding for bonding the lead to the electrode of the semiconductor element on the film carrier, the outer lead bonding for bonding the lead to the substrate, and the lower end portion of the wire are formed. The same effect can be obtained by applying the ball to a bump for bonding the electrode of the semiconductor element.

[0034]

According to the invention of claim 1, bonding is performed.
When transferring the load, bond the tool to the part to be joined.
Set the inclination when applying pressure to the bonding tool
By making it gentler than the inclination when releasing the pressure from
The fluctuation of the bonding load can be suppressed.

The invention of claim 2 is the same as the invention of claim 1.
And the bonding load is predetermined at the impact load value Fs.
By holding TFS for a time, the bonding load
Fluctuations can be suppressed.

According to the invention of claim 3, the position of the bonding tool is detected and the load command pattern (standard command F) is detected.
It is possible to remarkably reduce the change of the bonding load by feeding back to.

According to the fourth and fifth aspects of the invention, it is possible to eliminate false detection of landing due to disturbance and reduce fluctuations in the bonding load.

According to the invention of claim 6, the fluctuation of the load can be further reduced.

According to the invention of claim 7, the inclination angles α and β at the time of transfer of the bonding load and the signal level from the position detecting means added to the load command pattern can be parametrically changed, thereby making it possible to obtain a desired value. Bonding can be done. For example, the load fluctuation can be suppressed by reducing the level pu of the rising pulse fed back to the reference command during the holding time TFS of the collision load value Fs.

According to the invention of claim 8, it is sufficient to set any one of the collision load f, the bonding load Fs, and the collision speed Vs, and the setting work can be saved.

According to the ninth aspect of the invention, when the bonding load is set to the set value Fa, it is inclined at a predetermined inclination angle, so that the fluctuation of the bonding load can be reduced.

According to the tenth aspect of the invention, by detecting the position of the bonding tool and feeding it back to the load command pattern, the change in the bonding load can be significantly reduced.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a bonding apparatus according to a first embodiment of the present invention.

FIG. 2 is a signal diagram showing a method for controlling a bonding load according to the first embodiment.

FIG. 3 is a control block diagram showing a load command (reference command) and a motor command in the main control unit according to the first embodiment.

FIG. 4 is a diagram showing a load command (standard command) according to the third embodiment.

FIG. 5 is a diagram showing a load pattern according to a fourth embodiment.

FIG. 6 is a diagram showing a relationship between a collision load and a collision speed according to the fourth embodiment.

FIG. 7 is a signal diagram showing a motor command according to the fifth embodiment.

FIG. 8 is a diagram showing a motor command and an actual load according to the fifth embodiment.

FIG. 9 is a diagram showing a conventional bonding apparatus.

FIG. 10 is a diagram showing a conventional load pattern.

FIG. 11 is a diagram showing a conventional load pattern.

FIG. 12 is a signal diagram of a conventional bonding work.

[Explanation of symbols]

1 capillary, 2 wire, 3 ultrasonic horn, 4
Oscillator, 5 rotation fulcrum, 6 drive unit (linear motor), 7 position detection sensor (linear encoder), 8
Main controller, 9 motor drive circuit, 10 ultrasonic oscillator,
11 Search speed setting device, 12 Collision load setting device,
13 Bonding load setting device.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-231736 (JP, A) JP-A-6-89928 (JP, A) JP-A 61-208836 (JP, A) JP-A 64-- 90540 (JP, A) JP-A-1-244626 (JP, A) JP-A-2-239639 (JP, A) JP-A-3-203340 (JP, A) JP-A-4-348046 (JP, A) JP-A-7-142526 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/60

Claims (10)

(57) [Claims] 1. A bonding tool is brought close to a part to be bonded.
After detecting landing and landing, set the bonding load to impact load value F
In addition to shifting to s with a predetermined inclination, shock load value F
Inclination from s to bonding load set value Fa with a predetermined inclination
In the bonding method to be transferred, the bonding tool
From the inclination when the tool is pressed against the part to be bonded
The inclination when releasing pressure from the welded part of the tool is gentle
A bonding method characterized by the above. 2. The bonding load according to claim 1,
It has a special feature that TFS is maintained for a predetermined time at the impact load value Fs.
The bonding method according to claim 1, wherein the bonding method is a characteristic. 3. In a bonding apparatus for bonding a bonding tool by pressing the bonding tool onto the bonded portion, a position detecting means for detecting a position of the bonding tool with respect to the bonded portion, and a load for pressing the bonding tool onto the bonded portion. Standard command generating means for generating a command pattern, standard command correcting means for adding an amount corresponding to the change in the bonding tool position detected by the position detecting means to the load command pattern, and the bonding tool landed on the bonded portion. A bonding apparatus comprising: a drive unit that applies a bonding load according to the load command pattern after detecting the fact. 4. The position detecting means generates a rising pulse when the bonding tool moves away from the bonded portion, a falling pulse when the bonding tool approaches the bonded portion, and bonding when the falling pulse does not occur for a predetermined time. The bonding apparatus according to claim 3, wherein it is determined that the tool has landed on the bonded portion. 5. The bonding load is changed at a predetermined inclination according to a load command pattern when the falling pulse is not generated for a predetermined time, and is returned to the original load level at a predetermined inclination when the next falling pulse is generated. Claim to be
4. The bonding apparatus according to 4 . 6. The bonding apparatus according to claim 5, wherein a predetermined slope for returning the bonding load to an original load level is made gentler than a predetermined slope for changing the bonding load according to a load command pattern. 7. An inclination angle when transferring a bonding load,
Or claims, characterized in that the changeable signal level from the position detecting means to be added to the load command pattern
The bonding apparatus according to any one of claims 3 to 6 . 8. In a bonding apparatus for bonding a bonding tool by pressing the bonding tool onto the bonded part, a means for previously determining a relationship between a collision speed and a collision load of the bonding tool on the bonded part, and a collision load, a bonding load or a collision. A bonding apparatus comprising means for setting any one of the speeds and means for generating a load command pattern so that the collision load and the bonding load are equal. 9. After the bonding tool to detect the landing as close to the bonding portion, the bonding apparatus according to claim 8, characterized in that the bonding load is inclined transition to bonding load set value Fa with a predetermined gradient. 10. A position detecting means for detecting a position of the bonding tool with respect to a joined portion is provided, and an amount corresponding to a change in the bonding tool position detected by the position detecting means is added to the load command pattern.
The bonding apparatus according to claim 8 or 9 .