JP2017168735A - Wire bonding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for stably jointing a wire out of Au such as Ag to a semiconductor chip.SOLUTION: A wire bonding method connects a bonding wire to an electrode pad of a semiconductor chip by using a capillary. The wire bonding method includes steps of: applying a first ultrasonic output to the capillary before the capillary is grounded to the electrode pad; and allowing at least one of the capillary and a bonding stage to be oscillated to a direction along a surface of the electrode pad in a low frequency and a large fluctuation after the capillary is grounded.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a wire bonding method.

  Conventionally, an Au wire (gold wire) has been generally used in a wire bonding technique in which an electrode pad of a semiconductor chip and a lead frame are electrically connected by a metal wire. In recent years, studies have been conducted on the use of Ag wire (silver wire), which has higher reflectance and lower price than Au, for wire bonding (see paragraph [0008] of Patent Document 1).

JP, 2014-220424, A JP 2015-26646 A

However, since Ag is harder and more brittle than Au, there is a possibility that stable bonding cannot be achieved by the same bonding method as that for Au wire.
In order to improve the bondability of the wire, it is conceivable to use platinum (Pt) for the electrode pad of the semiconductor chip as described in Patent Document 2 (see paragraph [0006] and the like of Patent Document 2). However, there is a problem that the manufacturing cost of the semiconductor chip increases accordingly. In addition, there is a problem that the bondability to wires other than Ag is impaired.

  In view of the above, an object of the present invention is to provide a method for stably bonding a wire other than Au, such as Ag, to an electrode pad of a semiconductor chip in the wire bonding technique.

The inventors of the present invention have intensively studied to solve the above problems, and as a result, have arrived at the following aspects of the present invention.
That is, a method according to the first aspect of the present invention is a wire bonding method in which a bonding wire is connected to an electrode pad of a semiconductor chip using a capillary, and the wire bonding method is configured such that the capillary is grounded to the electrode pad. Before applying the first ultrasonic output to the capillary, and after the capillary is grounded, at least one of the capillary and the bonding stage is connected to the electrode pad at a lower frequency and a larger amplitude than the first ultrasonic output. Oscillating in a direction along the surface.

  According to the method according to the above aspect, the first ultrasonic output is applied to the capillary before the capillary contacts the electrode pad. As a result, the initial ball at the tip of the capillary comes into contact with the electrode pad of the semiconductor chip while performing ultrasonic vibration. Therefore, a relatively large load (impact) can be applied from the initial ball to the electrode pad surface of the semiconductor chip. As a result, the dirt and oxide film on the surfaces of the initial ball and the electrode pad can be more effectively removed, and the metal-to-metal adhesion between the bonding wire and the electrode pad can be made stronger. Furthermore, after the capillary is grounded, at least one of the capillary and the bonding stage is vibrated in a direction along the surface of the electrode pad at a frequency lower than that of the first ultrasonic output and with a larger amplitude. As a result, the tip of the capillary can be brought closer to a wider part of the surface of the electrode pad, so that the diameter of the first ball is increased and the bonding between the bonding wire and the electrode pad is made stronger. can do.

  According to the second aspect of the present invention, the wire bonding method further includes a step of applying a second ultrasonic output to the capillary after the capillary is grounded, wherein the first ultrasonic output is: Equal to or greater than the second ultrasound output. Within a certain range, the larger the first ultrasonic power applied before the capillary is grounded, the stronger the metal-to-metal bonding between the bonding wire and the electrode pad. Therefore, according to the second aspect, an effect equal to or greater than that of the first aspect can be obtained.

  According to the third aspect of the present invention, in the above wire bonding method, the capillary search speed, that is, the speed at which the capillary moves in the vertical direction to detect grounding is 10 mm / s or less. Depending on the device configuration, by slowing down the search speed, it is possible to lengthen the time during which the first ultrasonic output is applied while the initial ball is in contact with the electrode pad, and thereby the metal between the bonding wire and the electrode pad. Inter-bonding can be made stronger.

  According to a fourth aspect of the present invention, in the wire bonding method, the bonding wire is made of Ag. According to the wire bonding methods according to the first to third aspects, stable bonding can be performed even when an Ag wire is used.

  An inspection method according to a fifth aspect of the present invention includes a step of connecting a bonding wire to an electrode pad of a semiconductor chip by the above-described wire bonding method, and a step of performing a shear test of the bonding wire. According to this, the reliability of the inspection of the semiconductor chip alone (sampling inspection before shipping, etc.) can be improved.

FIG. 1 is a diagram schematically showing an example of a wire bonding apparatus and an object of the wire bonding method that can be used in a wire bonding method according to an embodiment of the present invention. FIG. 2 is a partial cross-sectional view illustrating an example of a semiconductor product manufactured using the wire bonding method according to an embodiment. FIG. 3 is an explanatory diagram for explaining a wire bonding method and its effects according to an embodiment. FIG. 4 is an explanatory diagram for explaining a wire bonding method and its effects according to an embodiment. FIG. 5 is an explanatory diagram for explaining a wire bonding method and its effects according to an embodiment. FIG. 6 is an explanatory diagram for explaining a wire bonding method and an effect thereof according to an embodiment. FIG. 7 is an example of an operation chart illustrating the operation of the wire bonding apparatus when the wire bonding method according to the embodiment is performed. FIG. 8 is a table showing data of a plurality of examples of the present invention together with data of a plurality of comparative examples. FIG. 9 is a diagram in which data of a plurality of examples and comparative examples in FIG. 8 are plotted on a coordinate plane.

  FIG. 1 is a diagram schematically showing an example of a wire bonding apparatus 1 that can be used in a wire bonding method according to an embodiment of the present invention and an object of the wire bonding method. As shown in FIG. 1, a wire bonding apparatus 1 that performs wire bonding to an electrode pad of a semiconductor chip 100 includes a capillary 10 that contacts and bonds a bonding wire 40 to a bond point, and generates ultrasonic waves in the capillary 10. On the other hand, an ultrasonic transducer 20 that applies ultrasonic vibration, an arm 30 that moves the capillary 10 and the ultrasonic transducer 20 up and down, front and rear, left and right, a drive unit 50 that drives the arm 30, and a drive unit 50 are provided. And a control unit 60 for controlling each unit including the control unit 60. The wire bonding apparatus 1 further includes a wire feeding apparatus for feeding the bonding wire 40 to the capillary 10 and extending from the tip of the capillary 10, a bonding stage (ie, stage) on which a semiconductor is placed, wiring, and the like. However, some of them are not shown.

  Next, an outline of a general process for connecting the electrode pad of the semiconductor chip 100 and the lead frame by wire bonding will be described. The semiconductor chip 100 is fixed to the support 200 with an adhesive such as an Ag paste. The tip of the bonding wire 40 extending from the tip of the capillary 10 is processed into a ball shape to form an initial ball 41. First, by driving the arm 30, the capillary 10 is brought close to the electrode pad surface of the semiconductor chip 100, and the initial ball 41 is brought into contact with the electrode pad surface. This contact state is referred to as “ground” in this specification. Next, ultrasonic vibration is applied to the capillary 10 by the ultrasonic vibrator 20. This destroys dirt and oxides on the surfaces of the initial balls 41 and the electrode pads, thereby performing intermetal bonding. Next, the capillary 10 is moved to the lead frame side, and the bonding wire 40 is bonded to the lead frame. Next, the tip of the bonding wire 40 is melted by discharge from an electric torch (not shown) to form a ball-shaped initial ball 41.

  FIG. 2 is a partial cross-sectional view showing an example in which the electrode pads of the LED chip 100 as an example of the semiconductor chip 100 and the lead frames 201 and 202 are electrically connected by the wire bonding method described above. In FIG. 2, reference numeral 42 denotes a first ball formed by deformation of the initial ball 41, and an end portion 43 of the bonding wire 40 opposite to the first ball 42 is electrically connected to the lead frames 201 and 202, respectively.

  In the present embodiment, a wire made from Ag is used as the bonding wire 40. As the bonding wire 40 using Ag as a raw material in the present plan, a wire mainly composed of Ag can be used in addition to a wire composed of 100% Ag. As a wire mainly composed of Ag, it is sufficient that Ag is 50% or more. For example, in this plan, a bonding wire 40 having Ag of 88%, Pd of 8.5%, and Au of 3.5% is preferably used. Can be adopted.

  Thus, when using the bonding wire 40 made of Ag as a raw material, in order to ensure a sufficient bonding strength between the electrode pad of the semiconductor chip 100 and the bonding wire 40, there is a wire bonding condition different from the case of the Au wire. Conceivable. Therefore, a test was conducted to search for suitable wire bonding conditions for improving the bonding strength between the electrode pads of the semiconductor chip 100 and the bonding wires 40 made of Ag as raw materials by changing the wire bonding conditions in various ways. Shear strength was used as an index of bonding strength between the bonding wire 40 and the electrode pad.

  In some cases, two control parameters of “ultrasonic output after grounding” and “bond load” are used as wire bonding conditions that affect the shear strength. According to a new experiment conducted by the inventors of the present invention, four control parameters such as “ultrasonic output before ground contact”, “search speed”, “number of scrub operations”, and “scrub operation amplitude” have a large share strength. It became clear that it could have an impact. In the following, these four control parameters will be described, and the reason why each control parameter affects the share strength will be described with reference to the drawings.

[Ultrasonic output before grounding]
In the conventional wire bonding technique, application of ultrasonic vibration to the capillary 10 is started after the grounding of the capillary 10 to the semiconductor chip 100 is detected. The state of application of such ultrasonic vibration is schematically shown in FIG. In FIG. 3A, the swing width of the capillary 10 to which ultrasonic vibration is applied is schematically represented by a double arrow fr. Since the initial ball 41 is already in contact with the semiconductor chip 100 in this state, the swing width a1 of the initial ball 41 is considerably smaller than the swing width fr due to the influence of friction between the two.

  On the other hand, in the present embodiment, application of ultrasonic vibration to the capillary 10 is continuously performed before the grounding of the capillary 10 with respect to the semiconductor chip 100 is detected. FIG. 3B schematically shows the deflection width fr of the capillary 10 to which ultrasonic vibration is applied in the state before grounding. In the state of FIG. 3B, the initial ball 41 at the tip of the capillary 10 is a free end. Therefore, when the capillary 10 vibrates with the same deflection width fr as in FIG. 3A, the initial ball 41 is not hindered by friction with the semiconductor chip 100, so that the case of FIG. It vibrates with a swing width a2 larger than the swing width a1.

  Therefore, at the moment when the capillary 10 descends from the state shown in FIG. 3B and the initial ball 41 comes into contact with the electrode pad of the semiconductor chip 100, the initial ball 41 has at least a deflection width a1 shown in FIG. It vibrates with a large amplitude. Therefore, at the moment when the initial ball 41 contacts the electrode pad of the semiconductor chip 100, a larger load (impact) can be applied to the electrode pad of the semiconductor chip 100 due to the vibration of the initial ball 41 having a relatively large swing width. . As a result, the dirt and oxide film on the surfaces of the initial ball 41 and the electrode pad can be more effectively removed, and the metal-to-metal adhesion between the bonding wire 40 and the electrode pad can be made stronger. Furthermore, within a certain range, it is considered that as the ultrasonic output before grounding is larger, the load (impact) applied to the electrode pad is larger, and the effect of strengthening the adhesion between metals is considered to be improved.

[Search speed]
An example of a method for detecting the grounding of the capillary 10 will be described with reference to FIG. This method is also used in this embodiment. In this method, the height H (see FIG. 1) of the capillary 10 is measured over time, and from the time t1 when the change in the actual measurement value of the height H indicated by the solid line (a) in FIG. At the time t2 when the change in the predicted value of the height H (indicated by a broken line (A)) estimated from the history of the actual value of the search load or the height H reaches a predetermined threshold (indicated by the width b), the capillary 10 Detect grounding. In this embodiment, the ultrasonic output fr1 before grounding is applied to the capillary 10 until the time t2 when the grounding is detected, and the ultrasonic output fr2 after grounding is applied to the capillary 10 after the time t2. Actually, since the initial ball 41 contacts the electrode pad of the semiconductor chip 100 at time t1, the pre-ground ultrasonic output fr1 is applied to the capillary 10 from time t1 to time t2.

  In this embodiment, the ground search speed is set to be relatively slow. The slopes of the solid line (A) and the broken line (A) in FIG. 4A correspond to the search speed. When the search speed is made slower than that in FIG. 4A, the slopes of the solid line (A) and the broken line (A) become gentle as shown in FIG. 4B. Since the threshold value b is constant, the time from the time point t1 to the time point t2 in FIG. 4B is longer than that in FIG. Then, the time for applying the pre-ground ultrasonic output fr1 to the capillary 10 in FIG. 4 (B) becomes longer than in the case of FIG. 4 (A). Therefore, the total amount of load (impact) applied to the electrode pad by the pre-ground ultrasonic output fr1 becomes larger when the search speed is slowed as shown in FIG. 4B than in the case of FIG. 4A. Therefore, the bonding between the bonding wire 40 and the electrode pad becomes stronger.

[Number of scrub operations and amplitude]
In this embodiment, after the capillary 10 is grounded, the capillary 10 is scrubbed. The scrub operation refers to an operation in which the capillary 10 is vibrated in a direction along the electrode pad surface at a lower frequency (about 500 Hz) and a larger amplitude (about 1 to 5 μm) than the ultrasonic vibration. More specifically, as shown in FIG. 5B, the capillary 10 grounded to the electrode pad of the semiconductor chip 100 is along a circular orbit having a radius r centered on the bond point B parallel to the surface of the electrode pad. And rotate it a predetermined number of times. In this case, the value of the radius r of the circular orbit corresponds to the amplitude (about 1 to 5 μm) of the scrub operation. (1) in FIG. 5 is a trajectory of the capillary 10 at the start of the scrubbing operation, and is an acceleration trajectory that enters the circular trajectory while accelerating from the bond point B. (3) of FIG. 5 shows the deceleration trajectory until the capillary 10 finishes rotating on the circular trajectory and returns to the bond point B.

  Thereby, the diameter of the first ball 42 can be increased. When Au is used as the electrode pad material, an AuAg alloy is most easily formed at the tip of the capillary 10 by ultrasonic vibration of the capillary 10 as shown in FIG. Therefore, in this embodiment, the tip of the capillary 10 can be brought closer to a wider part of the electrode pad surface by vibrating the capillary 10 in a direction along the electrode pad surface by a scrubbing operation after grounding. As shown in FIG. 6B, the AuAg alloy portion can be formed in a wider range. Therefore, according to this embodiment, the bonding wire 40 can be more firmly bonded to the electrode pad. The scrubbing operation is not limited to the operation of the capillary 10 but may be based on the operation on the stage side where the semiconductor chip 100 is placed.

The number of times that the capillary 10 shown in (2) of FIG. 5 is rotated is varied from 1 to 5 times, and the radius r of the circular orbit is varied within a range of 1 to 5 μm. Explored. Table 1 below shows examples of time (unit: ms) required for the scrubbing operation under these conditions.

  An example of the operation of the wire bonding apparatus 1 that performs the wire bonding method of the present embodiment described above will be described based on the operation chart of FIG. In the operation chart of FIG. 7, the horizontal axis is a time axis, the capillary height H of the wire bonding apparatus 1 when the wire bonding method according to the present embodiment is performed, the load Fw that the capillary 10 receives from the arm 3, and the semiconductor chip 100 receives. The load Fc, the ultrasonic output fr of the ultrasonic transducer 20, and the scrubbing operation of the capillary 10 are shown in the vertical axis direction.

  More specifically, when the capillary 10 descends from above toward the electrode pad surface of the semiconductor chip 100 and the capillary height H reaches a predetermined value H0 at time t0, the search speed is lowered. The output of the pre-ground ultrasonic output fr1 is started from time t0. When the ground contact of the capillary 10 is detected at a subsequent time t12, the set value of the ultrasonic output is changed from the pre-ground ultrasonic output fr1 to the post-ground ultrasonic output fr2. After the grounding, the ultrasonic output fr2 is applied to the capillary 10 only during the output time d from the grounding. Further, a scrubbing operation by vibration of the capillary 10 (or stage) is started at the time t12 of grounding. The rectangle in the scrubbing operation in FIG. 7 corresponds to one rotation of the capillary 10 described in (2) of FIG. The height r of the rectangle represents the amplitude of the scrub operation. The capillary 10 starts to rise with the end of the output time d of the ultrasonic output fr2 after grounding. Of the load Fw received by the capillary 10 from the arm 30, the load Fw1 before contact is a search load, and the load Fw2 after contact is a bond load. Time t12 represents the moment when the capillary 10 is grounded. It can also be considered that the moment of time t12 extended in the time axis direction corresponds to the time from time t1 to time t2 in FIG.

(Example)
An experiment for bonding an Ag wire to an electrode pad of an LED chip by a wire bonding method according to this embodiment was performed under a plurality of wire bonding conditions. Each experimental result will be described below as an example.
Implementation conditions common to each example were as follows.

Bonding wire material: 88% Ag, 8.5% Pd, 3.5% Au Bonding wire diameter: 25 μm
First ball diameter: 75 ± 10 μm

  The data of Examples 1-11 of the wire bonding method of this embodiment based on the above implementation conditions are shown in FIG. 8 together with the data of Comparative Examples 1-4. FIG. 8 shows the search speed, the ultrasonic output after contact, the ultrasonic output before contact, the scrub action amplitude, the number of scrub actions, and the first ball diameter ( x direction and y direction), the bonding area of the first ball and the electrode pad, the shear strength, and the judgment item, the judgment value, the difference between the shear strength and the judgment value, and the evaluation are described.

  Comparative Examples 1 and 2 are examples in which the ultrasonic output before grounding is not applied and the scrubbing operation after grounding is not performed. Comparative Examples 3 and 4 are examples in which the same pre-grounding ultrasonic output as that after the grounding is applied, the scrub operation after the grounding is not performed, and the search speed is relatively high. Examples 1 to 6 are examples in which the same ultrasonic output before grounding as the ultrasonic output after grounding is applied and the scrubbing operation after grounding is not performed. Examples 7 and 8 are examples in which an ultrasonic output before grounding larger than the ultrasonic output after grounding is applied and the scrubbing operation after grounding is not performed. Examples 9 and 10 are examples in which the same pre-ground ultrasonic output as the post-ground ultrasonic output is applied and the scrub operation after the ground is performed. Example 11 is an example in which a pre-ground ultrasonic output larger than the post-ground ultrasonic output is applied to perform a scrub operation after the ground.

FIG. 9 is a diagram in which the data of the example and the comparative example of FIG. 8 are plotted on a coordinate plane with the horizontal axis representing the bonding area and the vertical axis representing the shear strength. Numbers 1 to 11 surrounded by ○ represent Examples 1 to 11, respectively, and numbers 1 to 4 surrounded by Δ represent Comparative Examples 1 to 4, respectively. The straight line in the figure represents a regression line of the bonding area (μm ² ) and the shear strength (gf: gram weight) of Examples 1 to 6. When the joint area is x and the shear strength is y, the regression line is expressed by the following equation.
[Equation 1]

y = 0.0177x-24.636

The determination value in FIG. 8 was calculated based on the above formula. That is, the determination value was calculated as follows based on the bonding area.
[Equation 2]

Determination value = 0.0177 × joint area−24.636

Each example was evaluated according to the following criteria. That is, the quality of each example was evaluated by comparison with the regression line of FIG.
[Formula 3]

A: Share strength-judgment value> 2 gf
○: -2 gf ≤ shear strength-judgment value ≤ 2 gf
×: Share strength−judgment value <−2 gf

From FIGS. 8 and 9, compared with Comparative Examples 1 and 2 in which the ultrasonic output before grounding is not applied, in Examples 1 to 6 in which the ultrasonic output before grounding is applied, the shear strength can be stably secured. I understand. In order to firmly bond the bonding wire with the electrode pad, it is conceivable to increase the bonding area between the two, and by increasing the ultrasonic output as in Examples 1 to 6, the grounding area can be expanded. However, if the size of the element side (pad electrode) is limited, it is difficult to simply increase the ground area. Therefore, by performing as in Examples 7 to 11, the shear strength can be increased while suppressing an increase in the bonding area. That is, compared with Examples 1-6 which apply the same pre-grounding ultrasonic output as the post-grounding ultrasonic output, Examples 7, 8, and 11 applying a pre-grounding ultrasonic output larger than the post-grounding ultrasonic output. However, it can be seen that the share strength is further improved. Further, it can be seen that in Examples 9, 10, and 11 in which the scrub operation is performed, the shear strength is further improved as compared with Examples 1 to 6 in which the scrub operation is not performed.
In Comparative Examples 3 and 4 in which the search speed is increased compared to Examples 1 to 11, the shear strength is deteriorated. From this, it can be seen that a slower search speed is preferable.

“Search speed” and “Before grounding”, which are particularly suitable for strengthening the bonding between the bonding wire made of Ag wire and the electrode pad of the semiconductor chip (for example, LED chip) found by this experiment The conditions of “ultrasonic output”, “number of scrub operations”, and “scrub operation amplitude” are shown in the following Table 2 as “conditions of this embodiment”. For comparison, a condition in the case of a conventional wire bonding method using an Ag wire is described as “conventional condition”. Also, the reason for changing from “conventional conditions” to “conditions of the present embodiment” is also described as “reason for change”. The ultrasonic output values in the table are set values of the apparatus.

In Table 2 above, the search speed is 10 mm / s. However, in order to improve the shear strength, the search speed is preferably 10 mm / s or less and 5 mm / s or more.
In Table 2 above, the ultrasonic output before grounding is set to 520, which corresponds to an ultrasonic output about twice as large as the ultrasonic output after grounding when an Au wire is used. Within a certain range, the greater the ultrasonic output before grounding, the greater the load (impact) applied to the electrode pad during grounding, and the bonding strength improves. In order to improve the shear strength, it is preferable to set the ultrasonic output before grounding to about 1.00 to 1.08 times the ultrasonic output after grounding.
In Table 2 above, the number of scrub operations was 5 and the amplitude was 2 μm. In order to improve the shear strength, it is preferable that the number of scrub operations is one or more and the amplitude is 2 μm or more. On the other hand, the amplitude of the scrubbing operation is preferably ¼ or less of the wire diameter. This is because if the scrubbing operation is larger than this, an excessive load is applied to the wire and there is a risk of disconnection.
In the above embodiments and examples, the scrubbing motion is a motion along a circular orbit, but it may be a motion along an elliptical trajectory, in which case the half length of the major axis of the elliptical trajectory corresponds to the scrubbing motion amplitude. To do.

(Modification)
The wire bonding method according to the above embodiment can be used not only for the manufacture of a product having a semiconductor chip, but also for the purpose of improving the accuracy of inspection of a semiconductor chip alone (sampling inspection before shipment, etc.).
The wire bonding method according to the above embodiment is characterized by the following points in comparison with the conventional wire bonding method.

(1) Reduce the ground search speed.
(2) Apply ultrasonic output before grounding.
(3) The scrub operation after the grounding is performed.

All of these features (1) to (3) contribute to the improvement of the shear strength. When the shear strength is increased, there is a high possibility that a defect (pad peeling) occurs when the electrode pad is peeled off depending on the strength of the electrode pad when a force is applied to the bonded bonding wire.
Therefore, if the semiconductor chip extracted as a sample for inspection such as pre-shipment inspection is mounted on the evaluation substrate, and the wire bonding method of the above embodiment having the features (1) to (3) is applied, Wire bonding can be performed under conditions where pad peeling is intentionally likely to occur. That is, it is possible to perform a shear test under more severe conditions regarding pad peeling and to confirm whether or not there is pad peeling after the shear test. In this way, inspections such as a sampling inspection before shipment can be made more reliable. In particular, the conditions “(1) reduce the search speed of grounding” and “(2) apply ultrasonic output before grounding” increase the load (impact) on the electrode pad. It can be said that this is a condition that facilitates pad peeling.

  The present invention is not limited to the description of each aspect, each embodiment, and each example. Various modifications are also included in the present invention as long as those skilled in the art can easily conceive without departing from the scope of the claims. The contents of publications and the like specified in the present specification are all incorporated by reference.

DESCRIPTION OF SYMBOLS 1 Wire bonding apparatus 10 Capillary 20 Ultrasonic vibrator 30 Arm 40 Bonding wire (Ag wire)
41 Initial Ball 42 First Ball 43 End 50 Drive Unit 60 Control Unit 100 Semiconductor Chip 200 Supports 201 and 202 Lead Frame

Claims (5)

A wire bonding method for connecting a bonding wire to an electrode pad of a semiconductor chip using a capillary,
Applying a first ultrasonic output to the capillary before the capillary is grounded to the electrode pad;
Vibrating at least one of the capillary and the bonding stage in a direction along the surface of the electrode pad at a lower frequency and a larger amplitude than the first ultrasonic output after the capillary is grounded. Wire bonding method. Further comprising applying a second ultrasonic output to the capillary after the capillary is grounded;
The wire bonding method according to claim 1, wherein the first ultrasonic output is equal to or greater than the second ultrasonic output.   The wire bonding method according to claim 1, wherein a search speed of the capillary is 10 mm / s or less.   The wire bonding method according to claim 1, wherein the bonding wire is made of Ag. Connecting a bonding wire to an electrode pad of a semiconductor chip by the wire bonding method according to claim 1;
Carrying out a shear test of the bonding wire.

Images