Wire bonding apparatus, control device, and control method

Abstract

To provide a wire bonding apparatus, a control device, and a control method that can determine the quality of bump bonding at an earlier timing.SOLUTION: A wire bonding apparatus according to an embodiment includes a bonding tool that pays out a wire, a drive unit that drives the bonding tool, and a control unit that controls the bonding tool and the drive unit. The control unit executes a bonding process in which a ball formed at the tip of the wire is brought into contact with a first bonding point, the ball is transformed into a bump, and the bump is bonded to the first bonding point. The control unit further executes a lowering process in which the bonding tool holding the wire connected to the bump is raised, its position in the horizontal direction is changed, and then the bonding tool is lowered toward the first bonding point. The control unit determines whether the bump is bonded to the first bonding point on the basis of a predetermined detection value detected during the lowering process.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] FIELD Embodiments of the present invention relate to a wire bonding apparatus, a control apparatus, and a control method. [Background technology]

[0002] Wire bonding machines are widely used in the manufacturing process of semiconductor devices. Wire bonding machines form bumps and bond wires. There is a demand for technology that can determine the quality of bump bonding at an earlier stage for wire bonding machines. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-225637 Summary of the Invention [Problem to be solved by the invention]

[0004] The problem to be solved by the present invention is to provide a wire bonding apparatus, a control apparatus, and a control method that can determine the quality of the bump bonding at an earlier timing. [Means for solving the problem]

[0005] A wire bonding apparatus according to an embodiment includes a bonding tool that pays out a wire, a drive unit that drives the bonding tool, and a control unit that controls the bonding tool and the drive unit. The control unit executes a bonding process in which a ball formed at the tip of the wire is brought into contact with a first bonding point, the ball is transformed into a bump, and the bump is bonded to the first bonding point. The control unit further executes a lowering process in which the bonding tool holding the wire connected to the bump is raised, its position is changed in the horizontal direction, and then the bonding tool is lowered toward the first bonding point. The control unit determines whether the bump is bonded to the first bonding point based on a predetermined detection value detected during the lowering process. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a schematic diagram showing a wire bonding apparatus according to an embodiment. [Figure 2] FIG. 2 is a schematic diagram showing a part of the wire bonding apparatus according to the embodiment. [Figure 3] 3(a) to 3(c) are schematic diagrams showing an example of the wire bonding step. [Figure 4] FIG. 4 is a schematic diagram showing an example of a bump bonding step. [Figure 5] FIG. 5 is a schematic diagram showing a change in the Z position of the bonding tool. [Figure 6] Figure 6(a) is a schematic diagram showing the state of a bump when the bonding is good, and Figure 6(b) is a schematic diagram showing the state of a bump when the bonding is poor. [Figure 7] FIG. 7 is a schematic diagram showing another example of the bump bonding step. [Figure 8] FIG. 8 is a schematic diagram showing a change in the Z position of the bonding tool. [Figure 9] FIG. 9 is a schematic diagram showing an example of a bump bonding step. [Figure 10]FIG. 10 is a schematic diagram showing changes in the load on the bonding tool. [Figure 11] FIG. 11 is a schematic diagram showing a change in the Z position of the bonding tool. [Figure 12] FIG. 12 is a schematic diagram showing the hardware configuration. DETAILED DESCRIPTION OF THE INVENTION

[0007] Hereinafter, each embodiment of the present invention will be described with reference to the drawings. The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between parts, etc. are not necessarily the same as those in reality. Furthermore, even when the same part is shown, the dimensions and ratios may be different depending on the drawing. In this specification and each drawing, elements similar to those already described are designated by the same reference numerals, and detailed description will be omitted as appropriate.

[0008] The present invention relates to a wire bonding apparatus, a control device for controlling the apparatus, and a control method for the apparatus. For example, a wire bonding apparatus is used in a manufacturing process of a semiconductor device, and connects pads, which are electrodes of a semiconductor chip, to leads, which are electrodes of a lead frame, with wires, which are thin metal wires.

[0009] (First embodiment) FIG. 1 is a schematic diagram showing a wire bonding apparatus according to an embodiment. As shown in FIG. 1, the wire bonding apparatus 100 according to the embodiment includes a bonding head 10, a position detection unit 10a, an XY stage 20, a bonding stage 30, a load sensor 40, a camera device 50, and a control unit 60.

[0010] The bonding head 10 includes a bonding tool 11, an ultrasonic horn 12, a bonding arm 13, and a drive unit 14.

[0011] The bonding tool 11 pays out a wire 3 that serves as a bonding material. The bonding tool 11 is, for example, a bonding capillary. The wire 3 is, for example, an aluminum wire, a gold wire, a silver wire, or a copper wire. The bonding tool 11 brings the wire 3 into contact with a portion to be joined 2 of the workpiece 1 placed on a bonding stage 30, and applies a load to the portion to be joined 2. In this embodiment, the portion to be joined 2 is a first bonding point P1 or a second bonding point P2, which will be described later.

[0012] The position detection unit 10a detects the position in the Z direction of the bonding tool 11. For example, an origin is defined at a predetermined position, and the position detection unit 10a detects the position of the bonding tool 11 in the vertical direction from this origin. The position detection unit 10a is connected to the control unit 60 so as to be able to communicate with it.

[0013] The ultrasonic horn 12 generates ultrasonic vibrations. The ultrasonic horn 12 includes an ultrasonic vibrator that generates the ultrasonic vibrations. The ultrasonic horn 12 supports the bonding tool 11. The ultrasonic vibrations generated from the ultrasonic horn 12 are transmitted to the wire 3 via the bonding tool 11. When the wire 3 is in contact with the part to be bonded 2, the ultrasonic vibrations are transmitted to the wire 3, thereby bonding the wire 3 to the part to be bonded 2. The ultrasonic horn 12 is electrically connected to the control unit 60.

[0014] Bonding arm 13 supports ultrasonic horn 12. That is, bonding arm 13 supports bonding tool 11 via ultrasonic horn 12. Bonding arm 13 is provided rotatable about shaft 13a.

[0015] The driving unit 14 drives the bonding arm 13 in the Z direction around the shaft 13a. The driving unit 14 is, for example, a linear motor. As the bonding arm 13 moves in the Z direction, the bonding tool 11 and the ultrasonic horn 12 supported by the bonding arm 13 move in the Z direction. As the bonding tool 11 moves in the Z direction, the wire 3 can be brought into contact with a first bonding point P1 or a second bonding point P2, which will be described later, and a load can be applied from the bonding tool 11. The driving unit 14 is connected to the control unit 60 so as to be able to communicate with it.

[0016] In this specification, the direction connecting the bonding tool 11 and the workpiece 1 is referred to as the Z direction. The direction perpendicular to the Z direction is referred to as the X direction. The direction perpendicular to the Z direction and the X direction is referred to as the Y direction. For example, the Z direction is parallel to the vertical direction. The X direction and the Y direction are parallel to the horizontal plane. Also, here, the direction from the bonding tool 11 toward the workpiece 1 is referred to as "downward," and the direction opposite to "downward" is referred to as "upward."

[0017] The bonding head 10 is mounted on an XY stage 20. The XY stage 20 is movable in the X and Y directions. When the XY stage 20 moves in the X and Y directions, the bonding head 10 moves in the X and Y directions. In other words, the XY stage 20 functions as a positioning means for positioning the bonding tool 11 and other components provided on the bonding head 10 in the X and Y directions. The XY stage 20 is connected to a control unit 60 so as to be able to communicate with the control unit 60.

[0018] The bonding stage 30 supports the workpiece 1, which is the target of wire bonding. The bonding stage 30 supports the workpiece 1, for example, by suction. The workpiece 1 is a semiconductor chip such as an IC chip, or a substrate.

[0019] The load sensor 40 continuously detects the load applied to the bonding tool 11 from the portion to be bonded 2 of the workpiece 1. The load sensor 40 has, for example, a strain gauge. In the illustrated example, the load sensor 40 is attached to the bonding arm 13. The load sensor 40 is connected to the control unit 60 so as to be able to communicate with the control unit 60. The load sensor 40 outputs data of the detected load to the control unit 60.

[0020] The camera device 50 captures an image of the ball formed at the tip of the bonding tool 11. Based on the image acquired by the camera device 50, the parameters of the ball can be calculated.

[0021] The control unit 60 controls the operations of the bonding tool 11, the ultrasonic horn 12, the drive unit 14, and the XY stage 20. For example, the control unit 60 controls the wire payout and wire supply speed of the bonding tool 11. The control unit 60 controls the output of ultrasonic vibrations generated from the ultrasonic horn 12.

[0022] Furthermore, the control unit 60 can move the bonding tool 11 by operating the drive unit 14. More specifically, the control unit 60 can control the position of the bonding tool 11 in the Z direction by controlling the drive unit 14 to drive the bonding arm 13 in the Z direction. This allows the control unit 60 to control the magnitude of the load applied from the bonding tool 11 to the part to be bonded 2.

[0023] The position detection unit 10a acquires the position in the Z direction of the bonding tool 11 driven by the drive unit 14. The position detection unit 10a may be included in the control unit 60. For example, the position detection unit 10a includes an encoder. When the motor of the drive unit 14 operates, the position detection unit 10a detects the rotation direction and rotation position of the motor. The position detection unit 10a calculates the position of the bonding tool 11 in the Z direction from the detected rotation direction and position.

[0024] The control unit 60 can operate the XY stage 20 to move the bonding tool 11. More specifically, the control unit 60 can control the positions of the bonding tool 11 in the X and Y directions by controlling the XY stage 20 to drive the bonding head 10 in the X and Y directions.

[0025] FIG. 2 is a schematic diagram showing a part of the wire bonding apparatus according to the embodiment. 2, a bump 2a is formed on a portion 2 to be bonded of a workpiece 1, and a wire 3 is bonded to the bump 2a. A wire bonding apparatus 100 performs the formation of the bump 2a and the bonding of the wire 3 to the bump 2a. For example, the wire bonding apparatus 100 bonds the wire 3 to the portion 2 to be bonded by generating ultrasonic vibrations from an ultrasonic horn 12 while pressing the wire 3, which is fed from a bonding tool 11, against the portion 2 to be bonded.

[0026] Next, a series of steps for joining the wire 3 will be described. Figures 3(a) to 3(c) are schematic diagrams showing an example of the wire joining step. As shown in Figures 3(a) to 3(c), the wire bonding process includes three steps: a bump bonding process (Figure 3(a)), a first bonding process (Figure 3(b)), and a second bonding process (Figure 3(c)). In the illustrated example, a chip C is disposed on a substrate BA. A first bonding point P1 is located on the chip C, and a second bonding point P2 is located on the substrate BA. The substrate BA on which the chip C is disposed is an example of a workpiece 1. The first bonding point P1 and the second bonding point P2 are each an example of a part to be bonded 2. Bumps B1 and B2 are formed at the first bonding point P1 and the second bonding point P2, and a wire 3 is bonded to these bumps.

[0027] First, as shown in FIG. 3(a), a bump bonding process is performed, and a bump B1 is formed at a first bonding point P1. Specifically, a bonding tool 11 moves above the first bonding point P1 on the chip C. A wire 3 is inserted into the bonding tool 11, and a ball is formed at the tip of the wire 3 in advance. For example, a voltage is applied to the wire, and a discharge is generated at the tip of the wire, melting the tip of the wire. The molten metal curls into a spherical shape due to surface tension and solidifies, forming a ball. The bonding tool 11 descends toward the first bonding point P1, and the ball at the tip of the wire 3 comes into contact with the first bonding point P1. Ultrasonic waves are applied to the bonding tool 11 while a load is applied to the wire 3. As a result, the ball at the tip of the wire 3 deforms into a bump B1 on the chip C, and the bump B1 is bonded to the first bonding point P1. The wire 3 is then cut by ultrasonic waves, leaving the bump B1 on the chip C. Then, the bonding tool 11 moves from above the first bonding point P1 to above the second bonding point P2.

[0028] After the bump B1 is formed, the first bonding step is performed as shown in FIG. 3(b). A ball is formed in advance at the tip of the wire 3. The bonding tool 11 descends toward the second bonding point P2, and the ball at the tip of the wire 3 comes into contact with the second bonding point P2. Ultrasonic waves are applied to the bonding tool 11 while a load is applied to the wire 3. As a result, the ball at the tip of the wire 3 deforms into a bump B2 on the substrate BA, and the bump B2 is bonded to the second bonding point P2. After the bump B2 is formed, the wire 3 is not cut, and the wire 3 remains connected to the bump B2.

[0029] After the bump B2 is formed, a second bonding step is performed as shown in FIG. 3(c). With the bump B2 and the wire 3 connected, the bonding tool 11 moves upward a predetermined distance. Then, the bonding tool 11 bends the wire 3 and moves it from above the second bonding point P2 to the first bonding point P1. The wire 3 is bonded to the bump B1 on the chip C. Then, the wire 3 is cut by ultrasonic vibration, and the wire 3 is bonded to the chip C and the substrate BA. The above procedure is an example of wire bonding.

[0030] The illustrated example is not limiting, and the first bonding point may be located on the substrate BA, and the second bonding point may be located on the chip C. In this case, after a bump B1 is formed on the substrate BA, a bump B2 is formed on the chip C, and a wire 3 is bonded from the bump B2 to the bump B1.

[0031] Next, the bump bonding step will be described in more detail. Figure 4 is a schematic diagram showing an example of the bump bonding step. As shown in FIG. 4, the bump bonding process includes a search process R1, a bonding process R2, a reverse process R3, a lowering process R4, a tail forming process R5, a tail cutting process R6, and a spark process R7.

[0032] In the search process R1, a ball BO formed at the tip of the wire 3 inserted into the bonding tool 11 is brought into contact with the surface of the chip C. In the bonding process R2, a load and ultrasonic vibrations are applied to the ball BO, crushing it and bonding it to the surface of the chip C. In the reverse process R3, the bonding tool 11 is raised a predetermined distance and then its horizontal position is changed. In the lowering process R4, the bonding tool 11 is lowered to determine the height of the bump B1. In the reverse process R3 and the lowering process R4, the wire remains connected to the bump. In the tail forming process R5, the bonding tool 11 is raised to a predetermined position to form a tail. In the tail cutting process R6, ultrasonic vibrations are applied while the bonding tool 11 is raised, separating the tail from the bump B1. This forms the bump B1 on the chip C. In the subsequent spark process R7, a spark is generated at the tip of the wire 3 to melt the tip of the wire 3 and form a ball at the tip of the wire 3.

[0033] 4 shows the vibration state of ultrasonic vibration (US) and the detection state of the Z position of bonding tool 11 in steps R1 to R7. In FIG. 4, h1 indicates the position in the Z direction when bonding tool 11 is lowered to the lowest point in bonding step R2. For example, in bonding step R2, bonding tool 11 is lowered until a predetermined load is detected on bonding tool 11. Alternatively, bonding tool 11 is lowered until the descent speed of bonding tool 11 becomes equal to or less than a predetermined value. h2 indicates the Z position when bonding tool 11 is lowered until a predetermined load is applied to bonding tool 11 in descent step R4, or the Z position when bonding tool 11 is lowered until the descent speed of bonding tool 11 becomes equal to or less than a predetermined value.

[0034] In the bump bonding process, the control unit 60 determines whether the bump B1 is bonded well to the chip C. The Z position h1 and Z position h2 shown in FIG. 4 are used to determine whether the bonding of the bump B1 is good or bad. A good bond of the bump B1 means that the bump B1 is attached to the chip C with sufficient bonding strength. A poor bond of the bump B1 means that the bonding strength between the bump B1 and the chip C is insufficient. For example, if the bonding of the bump B1 is poor, the bump B1 will easily peel off from the surface of the chip C.

[0035] A specific method for determining whether the bonding tool is good or bad will be described below. Fig. 5 is a schematic diagram showing the change in the Z position of the bonding tool. 5, the horizontal axis represents time, and the vertical axis represents the Z position of the bonding tool 11. The solid line represents the change in Z position when the bump bonding is good, and the dotted line represents the change in Z position when the bump bonding is poor.

[0036] In the example shown in FIG. 5, if the bonding of the bump B1 is good, the bonding tool 11 descends to Z position h21 in the lowering step R4. If the bonding of the bump B1 is poor, the bonding tool 11 descends to Z position h22 in the lowering step R4. The bonding tool 11 descends until a predetermined load is detected. That is, the inventors of the present application discovered that the Z position of the bonding tool 11 at which a predetermined load is detected when the bonding is poor is lower than the Z position of the bonding tool 11 at which a predetermined load is detected when the bonding is good. This difference in Z position is thought to be due to the difference between the state of the bump B1 in the lowering step R4 when the bonding is good and the state of the bump B1 in the lowering step R4 when the bonding is poor.

[0037] Alternatively, the bonding tool 11 may be lowered at a constant speed, and the descent speed at that time may be detected. If the output from the drive unit 14 is constant when the bonding tool 11 is lowered, the descent speed of the bonding tool 11 decreases when the bonding tool 11 comes into contact with the bump B1. The control unit 60 acquires the Z position of the bonding tool 11 when the descent speed of the bonding tool 11 drops below a predetermined value during the descent process. If the Z position is acquired based on the descent speed, the Z position changes depending on whether the bonding is good or bad. This difference in Z position is also thought to be due to the difference between the state of the bump B1 during the descent process R4 when the bonding is good and the state of the bump B1 during the descent process R4 when the bonding is poor.

[0038] Figure 6(a) is a schematic diagram showing the state of a bump when the bonding is good, and Figure 6(b) is a schematic diagram showing the state of a bump when the bonding is poor. As shown in FIG. 6(a), in the reverse step R3 after the bonding step R2, the bonding tool 11 ascends and then moves a predetermined distance in a predetermined direction. For example, the bonding tool 11 moves a predetermined distance in the X direction. The direction of movement of the bonding tool 11 may be inclined relative to the horizontal plane. If the bonding is good, the position of the bump B1 bonded to the chip C in the reverse step R3 does not change regardless of the movement of the bonding tool 11 in the X direction. In the subsequent descending step R4, the bonding tool 11 descends, and the lower end of the bonding tool 11 contacts the joint between the bump B1 and the wire 3. At this time, a load is applied to the bonding tool 11. The load sensor 40 detects a predetermined load and stops the descent of the bonding tool 11. Alternatively, when a load is applied to the bonding tool 11, the descending speed of the bonding tool 11 decreases. When the lowering speed falls below a predetermined value, the driving unit 14 stops the lowering of the bonding tool 11.

[0039] On the other hand, if the bonding is poor, the bump B1 easily peels off from the chip C. Therefore, as shown in FIG. 6(b), in the reverse step R3, the position of the bump B1 is thought to change in accordance with the movement of the bonding tool 11 in the X direction. Thereafter, when the bonding tool 11 descends in the lowering step R4, the lower end of the bonding tool 11 contacts the side of the bump B1, not the joint between the bump B1 and the wire 3. When the bonding tool 11 contacts the side of the bump B1, a load is applied to the bonding tool 11. The descent of the bonding tool 11 stops based on either the load on the bonding tool 11 or the descent speed of the bonding tool 11. Therefore, the Z position at which the bonding tool 11 stops is lower than when the bonding tool 11 contacts the joint between the bump B1 and the wire 3.

[0040] The control unit 60 determines whether the bonding of the bump B1 is good or bad based on the change in the Z position corresponding to the quality of the bonding. Specifically, the control unit 60 calculates the difference between the Z position h1 detected in the bonding step R2 and the Z position (h21 or h22) detected in the lowering step R4. As can be seen from FIG. 5, the difference between the Z position h1 and the Z position h22 is smaller than the difference between the Z position h1 and the Z position h21. The control unit 60 compares the calculated difference with a preset threshold value. The threshold value is set to a value that is larger than the difference between the Z position h1 and the Z position h22 and smaller than the difference between the Z position h1 and the Z position h21. If the difference is equal to or greater than the threshold value, the control unit 60 determines that the bonding of the bump B1 is good. If the difference is less than the threshold value, the control unit 60 determines that the bonding of the bump B1 is bad.

[0041] If it is determined that the bonding of the bump B1 is poor, the control unit 60 stops the wire bonding process. The specific timing of the stop is arbitrary. For example, if it is determined that the bonding of the bump B1 is poor, the control unit 60 may immediately stop the wire bonding process. Alternatively, the control unit 60 may stop the wire bonding process after performing the tail cut process R6. In either case, the subsequent first bonding process is not performed. If it is determined that the bonding of the bump B1 is good, the control unit 60 performs the subsequent first bonding process and second bonding process.

[0042] The advantages of the first embodiment will be described. If the bumps are not bonded properly, they will easily peel off. This can result in poor electrical continuity in the workpiece. For this reason, it is desirable to judge the quality of the bond after the bumps are bonded. As reference examples, the following two methods can be considered for judging the quality of the bond.

[0043] In the first method, the electrical resistance between the bump and the workpiece or the capacitance of the workpiece is measured when the bump is bonded. If the bump is bonded properly, a change in the electrical resistance or capacitance occurs. From this change, it is possible to determine whether the bump is bonded properly.

[0044] In the second method, the Z position of the bonding tool in the second bonding process is used. If the bumps are bonded well and remain on the surface of the chip during the second bonding process, the wire will contact the bumps. If the bumps are not bonded sufficiently and do not remain on the surface of the chip, the wire will contact the surface of the chip. In other words, the Z position of the bonding tool in the second bonding process changes depending on whether the bumps are bonded well or not. Therefore, the quality of the bump bonding can be determined from the Z position of the bonding tool in the second bonding process.

[0045] However, the first method cannot determine whether the bump bond is good or bad if the workpiece is not conductive or has a low capacitance. In the second method, the bond is determined when the wire is bonded after the bump is formed. If the bond is determined to be bad, a person visually inspects the bump bond. If the bond is also determined to be bad by visual inspection, the wire is cut to ensure that the workpiece is determined to be bad in subsequent electrical property tests. This requires additional work when a bond failure occurs.

[0046] To address these issues, according to the first embodiment, the control unit 60 calculates the difference between the first position when the bonding tool 11 reaches its lowest position during the bonding step R2 and the second position when a predetermined load is applied to the bonding tool 11 during the lowering step R4 during bonding of the bump B1. The control unit 60 then determines whether the bump is properly bonded based on this difference. This method allows the quality of the bump to be determined regardless of the electrical characteristics of the workpiece. Furthermore, the quality of the bump can be determined based solely on information obtained during the bump bonding step. That is, the determination results are obtained earlier than the second bonding step. Therefore, it is possible to stop the execution of the first and second bonding steps depending on the determination results. Furthermore, by not executing the first and second bonding steps, there is no need to cut the wire for testing the electrical characteristics, which reduces the amount of work required when the bond is defective.

[0047] According to the first embodiment, regardless of the electrical characteristics of the workpiece, it is possible to determine the quality of the bump bonding at an earlier timing.

[0048] (Variation) FIG. 7 is a schematic diagram showing another example of the bump bonding step. The bump bonding process may include multiple reversing steps R3 and multiple lowering steps R4. In the example shown in Fig. 7, the bump bonding process includes a reversing step R3a, a lowering step R4a, a reversing step R3b, and a lowering step R4b. In other words, the reversing step R3 and the lowering step R4 are alternately repeated twice.

[0049] In the reverse step R3a, the bonding tool 11 rises, and then its position in the horizontal direction (e.g., the X direction) changes. In the lowering step R4a, the bonding tool 11 lowers until a predetermined load is applied to the bonding tool 11. In the reverse step R3b, the bonding tool 11 rises, and then moves in the -X direction. The horizontal direction in which the bonding tool 11 moves in the reverse step R3b is opposite to the horizontal direction in which the bonding tool 11 moves in the reverse step R3a. Thereafter, in the lowering step R4b, the bonding tool 11 lowers until a predetermined load is applied to the bonding tool 11. Thereafter, a tail forming step R5, a tail cutting step R6, and a sparking step R7 are performed, similar to the example shown in FIG. 4.

[0050] When multiple lowering steps are performed, the Z position is detected in each lowering step. For example, as shown in Figure 7, Z position h2 is detected in lowering step R4a, and Z position h3 is detected in lowering step R4b.

[0051] 5, if the bump B1 is not sufficiently bonded, the bump B1 also moves in accordance with the horizontal movement of the bonding tool 11. Therefore, in the lowering steps R4a and R4b, the Z position of the bonding tool 11 when a predetermined load is applied to the bonding tool 11 changes depending on whether the bonding of the bump B1 is good or bad.

[0052] FIG. 8 is a schematic diagram showing a change in the Z position of the bonding tool. In FIG. 8, the horizontal axis represents time, and the vertical axis represents the Z position of the bonding tool 11. The solid line indicates the change in Z position when the bump bonding is good. The dotted line indicates the change in Z position when the bump bonding is poor. For example, as shown in FIG. 8, when the bonding is good, Z position h21 is detected in the lowering step R4a, and Z position h31 is detected in the lowering step R4b. When the bonding is poor, Z position h22 is detected in the lowering step R4a, and Z position h32 is detected in the lowering step R4b. Z position h22 is located lower than Z position h21, and Z position h32 is located lower than Z position h31.

[0053] The control unit 60 calculates a first difference between the Z position h1 detected in the joining step R2 and the Z position (h21 or h22) detected in the lowering step R4a. The control unit 60 also calculates a second difference between the Z position h1 and the Z position (h31 or h32) detected in the lowering step R4b.

[0054] If the first difference is equal to or greater than a predetermined threshold and the second difference is equal to or greater than a threshold, the control unit 60 determines that the bonding of the bump B1 is good. If the first difference is less than the threshold or the second difference is less than the threshold, the control unit 60 determines that the bonding of the bump B1 is poor.

[0055] Alternatively, the control unit 60 may determine that the bonding of the bump B1 is good when the first difference is equal to or greater than a predetermined threshold value or when the second difference is equal to or greater than a threshold value. When the first difference is less than the threshold value and the second difference is less than the threshold value, the control unit 60 determines that the bonding of the bump B1 is poor.

[0056] When multiple reversing steps R3 and multiple lowering steps R4 are performed, the accuracy of the judgment can be further improved by judging whether the bonding of the bump B1 is good or bad using the Z position in each lowering step R4.

[0057] (Second embodiment) FIG. 9 is a schematic diagram showing an example of a bump bonding step. 4 and 7 show the Z position detected in the bump bonding process, while Fig. 9 shows the load detected in the bump bonding process.

[0058] 9, a load is applied to the bonding tool 11 in part of the search process R1, the bonding process R2, and the lowering process R4. The load applied to the bonding tool 11 is detected by a load sensor 40. In the second embodiment, the quality of the bonding of the bump B1 is determined based on the load on the bonding tool 11 detected in the lowering process R4.

[0059] Specifically, in the first embodiment, in the lowering step R4, the bonding tool 11 descends until a predetermined load is detected. In the second embodiment, in the lowering step R4, the bonding tool 11 descends until the bonding tool 11 reaches a predetermined Z position. The predetermined Z position is set to a position where the bonding tool 11 contacts the bump B1 when the bonding of the bump B1 is good. As shown in FIG. 5, when the bonding of the bump B1 is good, the bonding tool 11 contacts the bump B1 at a higher position than when the bonding of the bump B1 is poor. In other words, when comparing when the bonding tool 11 is at the same Z position, the load on the bonding tool 11 when the bonding of the bump B1 is good is greater than the load on the bonding tool 11 when the bonding of the bump B1 is poor.

[0060] FIG. 10 is a schematic diagram showing changes in the load on the bonding tool. In FIG. 10, the horizontal axis represents time, and the vertical axis represents the load on the bonding tool 11. The solid line represents the change in load when the bump is well bonded. The dotted line represents the change in load when the bump is poorly bonded. In the example shown in FIG. 10, when the bump B1 is well bonded, a load L1 is detected when the bonding tool 11 reaches a predetermined Z position in the lowering step R4. When the bump B1 is poorly bonded, a load L2 is detected when the bonding tool 11 reaches a predetermined Z position in the lowering step R4. The load L2 is smaller than the load L1.

[0061] The control unit 60 compares the load detected in the lowering step R4 with a predetermined threshold value. The threshold value is set to a value between the load L1 and the load L2. If the detected load is equal to or greater than the threshold value, the control unit 60 determines that the bonding is good. If the detected load is less than the threshold value, the control unit 60 determines that the bonding is poor. If the bonding of the bump B1 is determined to be poor, the control unit 60 stops the wire bonding step.

[0062] According to the second embodiment, similar to the first embodiment, it is possible to determine the quality of the bump bonding at an earlier timing, regardless of the electrical characteristics of the workpiece.

[0063] (Third embodiment) In the third embodiment of the present invention, in the lowering step R4, the period (length of time) from when the bonding tool 11 starts to lower until a predetermined load is applied to the bonding tool 11 is detected. The control unit 60 determines whether the bonding of the bump B1 is good or bad based on that period.

[0064] FIG. 11 is a schematic diagram showing a change in the Z position of the bonding tool. In FIG. 11, as in FIG. 5, the horizontal and vertical axes represent time and Z position, respectively. The solid and dotted lines represent the change in Z position when the bump bonding is good and bad, respectively. In the example shown in FIG. 11, when the bonding of the bump B1 is good, the length of time from when the bonding tool 11 starts to descend in the lowering step R4 until a predetermined load on the bonding tool 11 is detected is period p1. When the bonding of the bump B1 is bad, the length of time from when the bonding tool 11 starts to descend in the lowering step R4 until a predetermined load on the bonding tool 11 is detected is period p2. Period p2 is longer than period p1.

[0065] The control unit 60 compares the detected period with a predetermined threshold value. The threshold value is set to a value between the period p1 and the period p2. If the detected period is less than the threshold value, the control unit 60 determines that the bonding is good. If the detected period is equal to or greater than the threshold value, the control unit 60 determines that the bonding is poor. If the bonding of the bump B1 is determined to be poor, the control unit 60 stops the wire bonding process.

[0066] According to the third embodiment, similar to the first embodiment, it is possible to determine the quality of the bump bonding at an earlier timing, regardless of the electrical characteristics of the workpiece.

[0067] The second or third embodiment described above can also be applied to a bump bonding process in which a plurality of reversing steps R3 and a plurality of lowering steps R4 are performed, as shown in the modified example of the first embodiment.

[0068] According to each embodiment of the present invention described above, the control unit 60 can determine whether or not the bonding of the bump to the first bonding point is good based on the predetermined detection value detected in the lowering step R4.

[0069] In the first embodiment, the "predetermined detection value" is the second position of the bonding tool 11 when a predetermined load is applied to the bonding tool 11 in the lowering step R4. The control unit 60 acquires the first position of the bonding tool 11 when the bonding tool 11 is lowered to the lowest position in the bonding step R2. Then, the control unit 60 compares the difference between the first position and the second position with a preset threshold value to determine whether the bonding of the bump B1 is good or bad.

[0070] In the second embodiment, the "predetermined detection value" is the load on the bonding tool 11 when the bonding tool 11 descends to a predetermined position in the descending step R4. The control unit 60 compares the load with a preset threshold value and determines whether the bonding of the bump B1 is good or bad.

[0071] In the third embodiment, the "predetermined detection value" is the period from the start of the lowering step R4 to the application of a predetermined load to the bonding tool 11. The control unit 60 compares the period with a preset threshold value and determines whether the bonding of the bump B1 is good or bad.

[0072] FIG. 12 is a schematic diagram showing the hardware configuration. 12 is used as the control unit 60. The computer 90 includes a CPU 91, a ROM 92, a RAM 93, a storage device 94, an input interface 95, an output interface 96, and a communication interface 97.

[0073] The ROM 92 stores a program that controls the operation of the computer 90. The ROM 92 stores a program necessary for causing the computer 90 to perform each of the above-described processes. The RAM 93 functions as a storage area in which the programs stored in the ROM 92 are expanded.

[0074] The CPU 91 includes a processing circuit. The CPU 91 uses a RAM 93 as a work memory and executes a program stored in at least one of a ROM 92 and a storage device 94. During program execution, the CPU 91 controls each component via a system bus 98 and executes various processes.

[0075] The storage device 94 stores data necessary for executing the program and data obtained by executing the program.

[0076] The input interface (I / F) 95 can connect the computer 90 to an input device 95a. The input I / F 95 is, for example, a serial bus interface such as USB. The CPU 91 can read various data from the input device 95a via the input I / F 95.

[0077] The output interface (I / F) 96 can connect the computer 90 and an output device 96a. The output I / F 96 is, for example, a video output interface such as a Digital Visual Interface (DVI) or a High-Definition Multimedia Interface (HPMI (registered trademark)). The CPU 91 can transmit data to the output device 96a via the output I / F 96 and cause the output device 96a to display an image.

[0078] The communication interface (I / F) 97 can connect the computer 90 to a server 97a external to the computer 90. The communication I / F 97 is, for example, a network card such as a LAN card. The CPU 91 can read various data from the server 97a via the communication I / F 97.

[0079] The storage device 94 includes one or more selected from a hard disk drive (HDD) and a solid state drive (SSD). The input device 95a includes one or more selected from a mouse, a keyboard, a microphone (voice input), and a touchpad. The output device 96a includes one or more selected from a monitor, a projector, a printer, and a speaker. A device having the functions of both the input device 95a and the output device 96a, such as a touch panel, may also be used.

[0080] Each process executed by the control unit 60 may be realized by one computer 90 or by a plurality of computers 90 working together.

[0081] The various data processing operations described above may be recorded as a computer-executable program on a magnetic disk (such as a flexible disk or hard disk), an optical disk (such as a CD-ROM, CD-R, CD-RW, DVD-ROM, DVD±R, or DVD±RW), a semiconductor memory, or other non-transitory computer-readable storage medium.

[0082] For example, information recorded on a recording medium can be read by a computer (or an embedded system). The recording medium may have any recording format (storage format). For example, a computer reads a program from the recording medium and causes a CPU to execute instructions written in the program based on the program. The computer may acquire (or read) the program via a network.

[0083] Embodiments of the invention include the following features. (Feature 1) A bonding tool that pays out wire, a driving unit that drives the bonding tool; a control unit that controls the bonding tool and the driving unit, The control unit a bonding step of contacting a ball formed at the tip of the wire with a first bonding point, transforming the ball into a bump, and bonding the bump to the first bonding point; a lowering step of raising the bonding tool holding the wire connected to the bump, changing its position in a horizontal direction, and then lowering the bonding tool toward the first bonding point; Run The control unit determines whether the bonding of the bump to the first bonding point is good or bad based on a predetermined detection value detected in the lowering step. (Feature 2) The detected value is a position of the bonding tool when a predetermined load is applied to the bonding tool in the lowering step; a position of the bonding tool when the descending speed of the bonding tool changes to a predetermined value or less in the descending step; a load on the bonding tool when the bonding tool is lowered to a predetermined position in the lowering step; and a period from the start of the lowering step to the application of a predetermined load to the bonding tool; Feature 1. The wire bonding apparatus according to feature 1, comprising one or more selected from the following: (Feature 3) the control unit acquires a first position when the bonding tool is lowest in the bonding step, the detected value includes a second position of the bonding tool when a predetermined load is applied to the bonding tool in the lowering step; 2. The wire bonding apparatus according to claim 1, wherein the control unit determines that the bonding of the bump is defective when the difference between the first position and the second position is less than a preset threshold value. (Feature 4) The control unit When it is determined that the bonding of the bump is good, a first bonding step is carried out in which the bonding tool is moved above a second bonding point, the bonding tool with a ball formed at the tip of the wire is lowered, and the ball is brought into contact with the second bonding point; If the bonding of the bump is determined to be defective, the first bonding step is not performed. 4. The wire bonding apparatus according to any one of the first to third features. (Feature 5) A control device for controlling a wire bonding apparatus including a bonding tool that pays out a wire and a drive unit that drives the bonding tool, a bonding step of contacting a ball formed at the tip of the wire with a first bonding point, transforming the ball into a bump, and bonding the bump to the first bonding point; a lowering step of raising the bonding tool holding the wire connected to the bump, changing its position in a horizontal direction, and then lowering the bonding tool toward the first bonding point; causing the wire bonding apparatus to execute the above; a control device that determines whether or not the bonding of the bump to the first bonding point is good based on a predetermined detection value detected in the lowering step; (Feature 6) A method for controlling a wire bonding apparatus including a bonding tool that pays out a wire and a drive unit that drives the bonding tool, comprising: a bonding step of contacting a ball formed at the tip of the wire with a first bonding point, transforming the ball into a bump, and bonding the bump to the first bonding point; a lowering step of raising the bonding tool holding the wire connected to the bump, changing its position in a horizontal direction, and then lowering the bonding tool toward the first bonding point; causing the wire bonding apparatus to execute the above; A control method for determining whether or not the bonding of the bump to the first bonding point is good based on a predetermined detection value detected in the lowering step.

[0084] According to the embodiment described above, a wire bonding apparatus is provided that can determine the quality of the bump bonding at an earlier timing, regardless of the electrical characteristics of the workpiece. Furthermore, by having the control unit (control device) execute the above-described method for determining the quality of the bonding in the bump bonding process, the quality of the bump bonding can be determined at an earlier timing, regardless of the electrical characteristics of the workpiece. According to the above-described control method by the control unit, the quality of the bump bonding can be determined at an earlier timing, regardless of the electrical characteristics of the workpiece.

[0085] Although several embodiments of the present invention have been described above, these embodiments are presented by way of example only and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, modifications, etc. can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as set forth in the claims. Furthermore, the above-described embodiments can be implemented in combination with each other. [Explanation of symbols]

[0086] 1: Workpiece, 2: Part to be bonded, 2a: Bump, 3: Wire, 10: Bonding head, 10a: Position detection unit, 11: Bonding tool, 12: Ultrasonic horn, 13: Bonding arm, 13a: Shaft, 14: Drive unit, 20: XY stage, 30: Bonding stage, 40: Load sensor, 50: Camera device, 60: Control unit, 100: Wire bonding device, B1, B2: Bump, BA: Substrate, BO: Ball, C: Chip, P1: First bonding point, P2: Second bonding point, R1: Search process, R2: Bonding process, R3, R3a, R3b: Reverse process, R4, R4a, R4b: Lowering process, R5: Tail formation process, R6: Tail cut process, R7: Spark process, h1,h2,h21,h22,h3,h31,h32: Z position, L1,L2: Load, p1,p2: Period

Claims

1. A bonding tool that pays out wire, a driving unit that drives the bonding tool; a control unit that controls the bonding tool and the driving unit, The control unit a bonding step of contacting a ball formed at the tip of the wire with a first bonding point, transforming the ball into a bump, and bonding the bump to the first bonding point; a lowering step of raising the bonding tool holding the wire connected to the bump, changing its position in a horizontal direction, and then lowering the bonding tool toward the first bonding point; Run The control unit determines whether or not the bonding of the bump to the first bonding point is good based on a predetermined detection value detected in the lowering step.

2. The detected value is a position of the bonding tool when a predetermined load is applied to the bonding tool in the lowering step; a position of the bonding tool when the descending speed of the bonding tool changes to a predetermined value or less in the descending step; a load on the bonding tool when the bonding tool is lowered to a predetermined position in the lowering step; and a period from the start of the lowering step to the application of a predetermined load to the bonding tool; The wire bonding apparatus of claim 1 , comprising one or more selected from:

3. the control unit acquires a first position when the bonding tool is lowered to the lowest position in the bonding step, the detected value includes a second position of the bonding tool when a predetermined load is applied to the bonding tool in the lowering step, 2. The wire bonding apparatus according to claim 1, wherein the control unit determines that the bonding of the bump is defective when a difference between the first position and the second position is less than a preset threshold value.

4. The control unit When it is determined that the bonding of the bump is good, a first bonding step is carried out in which the bonding tool is moved above a second bonding point, the bonding tool with a ball formed at the tip of the wire is lowered, and the ball is brought into contact with the second bonding point; If the bonding of the bump is determined to be defective, the first bonding step is not performed.

4. The wire bonding apparatus according to claim 1.

5. A control device for controlling a wire bonding apparatus including a bonding tool that pays out a wire and a drive unit that drives the bonding tool, a bonding step of contacting a ball formed at the tip of the wire with a first bonding point, transforming the ball into a bump, and bonding the bump to the first bonding point; a lowering step of raising the bonding tool holding the wire connected to the bump, changing its position in a horizontal direction, and then lowering the bonding tool toward the first bonding point; causing the wire bonding apparatus to execute the above; a control device that determines whether or not the bonding of the bump to the first bonding point is good based on a predetermined detection value detected in the lowering step;

6. A method for controlling a wire bonding apparatus including a bonding tool that pays out a wire and a drive unit that drives the bonding tool, comprising: a bonding step of contacting a ball formed at the tip of the wire with a first bonding point, transforming the ball into a bump, and bonding the bump to the first bonding point; a lowering step of raising the bonding tool holding the wire connected to the bump, changing its position in a horizontal direction, and then lowering the bonding tool toward the first bonding point; causing the wire bonding apparatus to execute the above; A control method for determining whether or not the bonding of the bump to the first bonding point is good based on a predetermined detection value detected in the lowering step.

Images