Bonding apparatus, method for controlling the bonding apparatus, and control program for the bonding apparatus

Abstract

The present invention provides a bonding apparatus that can properly correct the bending of the wire tail and accurately guide the formed free air ball to the target position for bonding. [Solution] The bonding apparatus comprises an actuator that moves a capillary through which a wire is inserted in the direction of wire insertion, a clamper that performs clamping and releasing actions on the wire, a torch that forms a free air ball at the tip of the wire, and a control unit that controls the actuator, clamper and torch. The control unit forms a free air ball with the torch while the wire is clamped by the clamper, operates the actuator to bring the capillary close to the free air ball, operates the actuator while the clamper has released the wire to pull the capillary down toward the bonding target, and presses the free air ball against the bonding target to fix it in place.

Description

Technical Field

[0001] The present invention relates to a bonding apparatus, a control method for the bonding apparatus, and a control program for the bonding apparatus.

Background Art

[0002] A bonding apparatus is known that connects an electrode of a semiconductor chip fixed on a substrate to an electrode on the substrate with a bonding wire, or forms a pin wire on such an electrode. For example, after forming a free air ball at the tip of a wire, a cut is made in the middle of the wire with a wire cutter or the like, and after bonding to a target electrode, the wire is pulled and cut by the cut to form a pin wire (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Bonding wires extending from a capillary may experience bending in the wire tail due to rebound during previous bonding or the impact of electrical discharge forming a free air ball at the tip. Bending of the wire tail can cause misalignment of the bonding position. Patent Document 1 discloses a process in which the bonding wire is pulled up after forming a free air ball, the free air ball is brought into contact with the tip of the capillary, and then bonded to the electrode pad. While it is expected that bending of the wire tail can be corrected by moving the wire tail relative to the insertion hole of the fixed capillary in this way, this process uses the pull-back force of the tensioner of the wire supply device to move the delicate wire tail with the molten free air ball formed on it independently, and there is a risk that the free air ball may fall off or become displaced due to the impact of the free air ball coming into contact with the tip of the capillary.

[0005] This invention was made to solve these problems and provides a bonding apparatus that can properly correct the bending of the wire tail and accurately guide the formed free air ball to the target position for bonding. [Means for solving the problem]

[0006] A bonding apparatus according to a first aspect of the present invention includes an actuator that moves a capillary through which a wire is inserted in the direction of wire insertion, a clamper that performs clamping and releasing operations on the wire, a torch that forms a free air ball at the tip of the wire, and a control unit that controls the actuator, clamper and torch. The control unit forms a free air ball with the torch while the wire is clamped by the clamper, operates the actuator to bring the capillary close to the free air ball, operates the actuator to pull the capillary down toward the bonding target while the clamper has released the wire, and presses the free air ball against the bonding target to fix it in place.

[0007] A second aspect of the present invention provides a method for controlling a bonding apparatus, comprising: a free air ball forming step in which a wire supplied from a supply device is clamped by a clamper and a free air ball is formed on the tip of the wire by a torch; a proximity step in which an actuator is operated to move a capillary through which the wire is inserted in the insertion direction and bring it close to the free air ball; and a bonding step in which, with the clamper released from the wire, the actuator is operated to pull the capillary down toward the bonding object, pressing the free air ball against the bonding object and fixing it in place.

[0008] The control program for the bonding apparatus in the third aspect of the present invention causes the computer to execute the following steps: a free air ball forming step in which a wire supplied from a supply device is clamped with a clamper and a free air ball is formed on the tip of the wire with a torch; a proximity step in which an actuator is operated to move the capillary through which the wire is inserted in the insertion direction and bring it close to the free air ball; and a bonding step in which, with the clamper released from the wire, the actuator is operated to pull the capillary down toward the bonding object and press the free air ball against the bonding object to fix it in place. [Effects of the Invention]

[0009] The present invention provides a bonding apparatus that can appropriately correct the bending of the wire tail and accurately guide the formed free air ball to the target position for bonding. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic diagram of the bonding apparatus according to this embodiment, viewed from the side. [Figure 2] This is a schematic diagram of the bonding apparatus according to this embodiment, viewed from above. [Figure 3] This is a system configuration diagram of the bonding equipment. [Figure 4] This is a process diagram showing the procedure for forming pin wires. [Figure 5]This is a process diagram showing the procedure for forming a loop wire according to another embodiment. [Figure 6] This is a process diagram showing the procedure when there is one clamper according to another embodiment. [Modes for carrying out the invention]

[0011] Figure 1 is a schematic diagram of the bonding apparatus 100 according to this embodiment, viewed from the side. Figure 2 is a schematic diagram of the same bonding apparatus 100, viewed from above. The bonding apparatus 100 shown in the figures is simplified for the sake of understanding, and the size and shape of its elements may differ from those of an actual apparatus. Elements that are not directly related to the characteristic elements of this embodiment may also be omitted. However, this is not intended to show any differences from an actual bonding apparatus.

[0012] The bonding apparatus 100 is a device that forms pin wires at predetermined positions on substrates, wafers, lead frames, etc., which are to be bonded. Figure 1 shows how pin wires 310 are formed on pad electrodes 321 on substrate 320, which is to be bonded. The substrate 320 is fixed to the upper surface of the stage 170. In this embodiment, as shown in the coordinate axes in the figure, the vertical axis is the Z axis and the horizontal plane is the XY plane. The upper surface of the stage is parallel to the XY plane.

[0013] The XY table 160 is displaced in the XY plane relative to the upper surface of the stage 170 by the driving of a portion of the actuator 150. The support base 161 is fixed to the XY table 160 and mainly directly or indirectly supports the torch 111, capillary 112, transducer 113, Z rotation mechanism 114, support arm 122, slide mechanism 123, first clamper 131, second clamper 132, imaging unit 140, and wire cutter 200.

[0014] The torch 111 is equipped with a discharge electrode at its tip. When voltage is applied to the discharge electrode of the torch 111, a molten free air ball (FAB) is formed at the tip of the wire 300 that is fed out from the tip of the capillary 112. The specific procedure for generating the FAB will be described later. The capillary 112 guides the wire 300, which is inserted vertically, and supplies it to the pad electrode 321, and during bonding, its tip presses the wire 300 against the pad electrode 321. During bonding, the transducer 113 applies ultrasonic vibrations near the tip of the wire 300 via the capillary 112, fixing the FAB to the pad electrode 321. The transducer 113 may also apply heat to the FAB.

[0015] The first clamper 131 has a hand that grips the wire 300 at the top of the capillary 112 and performs gripping and releasing operations on the wire 300 according to the control of the bonding device 100. The capillary 112, transducer 113, and first clamper 131 are supported by a Z-rotation mechanism 114. The Z-rotation mechanism 114 is supported at its base end by a support base 161 and is displaced in the Z-axis direction relative to the support base 161 by driving a part of the actuator 150. That is, the capillary 112, transducer 113, and first clamper 131 can move closer to and further away from the surface of the stage 170 in accordance with the operation of the Z-rotation mechanism 114.

[0016] The second clamper 132 is positioned above the first clamper 131 and, like the first clamper 131, has a hand for gripping the wire 300, and performs gripping and releasing operations on the wire 300 according to the control of the bonding device 100. The second clamper 132 is supported and fixed to a support base 161, and the position for gripping and releasing the wire 300 is at a constant height from the surface of the stage 170. The wire 300 is a bonding wire supplied from a wire supply unit (not shown) including a tensioner and a rotating spool. The material of the wire 300 may be, for example, gold wire, silver wire, copper wire, etc.

[0017] The wire cutter 200 is a cutter for forming a notch in the wire 300. The wire cutter 200 is mainly composed of a cutting portion 210 and a receiving portion 220. The cutting portion 210 and the receiving portion 220 are arranged opposite to each other, and when a part of the actuator 150 is driven, they approach each other (close) or separate from each other (open). The notch formed in the wire 300 is a scratch or dent, and when pulled from both sides thereof, tensile stress concentrates and breaks the wire 300.

[0018] The wire cutter 200 is supported by the support arm 122 at its base end portion, and the support arm 122 is supported by the slide mechanism 123 at its base end portion. The slide mechanism 123 is displaced in the horizontal direction with respect to the support base 161 when a part of the actuator 150 is driven. Due to this horizontal displacement, an operation is realized in which the cutting portion 210 and the receiving portion 220 in the separated state (open state) are inserted so as to sandwich the wire 300 fed out from the capillary 112 in the horizontal direction or pulled out in the reverse direction.

[0019] The imaging unit 140 includes an imaging element that outputs an image signal and an optical system that forms an image of the substrate 320 on the imaging element. The bonding apparatus 100 recognizes the positions of the substrate 320 and the like using the image signal output by the imaging unit 140, and displaces the XY table 160 and the like.

[0020] FIG. 3 is a system configuration diagram of the bonding apparatus 100. The control system of the bonding apparatus 100 mainly includes a control unit 190, a storage unit 181, an input / output device 182, a torch 111, a transducer 113, a first clamper 131, a second clamper 132, an imaging unit 140, and an actuator 150. Elements involving displacement such as the Z rotation mechanism 114, the XY table 160, and the wire cutter 200 are driven by the corresponding actuators among the actuators 150 provided in the bonding apparatus 100.

[0021] The control unit 190 is a processor (CPU: Central Processing Unit) that controls the bonding apparatus 100 and executes program execution processing. The processor may be configured to cooperate with an arithmetic processing chip such as an ASIC (Application Specific Integrated Circuit) or a GPU (Graphics Processing Unit). The control unit 190 reads out the control program stored in the storage unit 181 and executes various processes related to bonding.

[0022] The storage unit 181 is a non-volatile storage medium and is configured by, for example, an HDD (Hard Disk Drive). In addition to the program that controls and executes the bonding apparatus 100, the storage unit 181 can store various parameter values, functions, look-up tables, etc. used for control and arithmetic operations. The input / output device 182 includes, for example, a keyboard, a mouse, and a display monitor, and is a device that receives menu operations by an operator and presents information to the operator. For example, the control unit 190 may display the image acquired from the imaging unit 140 on the display monitor, which is one of the input / output devices 182.

[0023] When the torch 111 receives a discharge instruction signal from the control unit 190, it applies a voltage to the electrode. When the voltage application to the electrode is executed, an arc discharge occurs between the electrode and the tip of the wire, and a FAB is formed at the tip of the wire 300. When the transducer 113 receives a vibration signal from the control unit 190, it vibrates the vibrator. The ultrasonic vibration by the transducer 113 contributes to the bonding of the wire 300.

[0024] The first clamper 131 and the second clamper 132 execute an opening / closing operation in response to an instruction signal from the control unit 190. In the state where the wire 300 is set in the bonding apparatus 100, the opening operation is an operation of sandwiching the wire 300, and the closing operation is an operation of releasing the wire 300.

[0025] The imaging unit 140 receives an imaging request signal from the control unit 190, performs imaging, and transmits the image output by the image sensor as an image signal to the control unit 190. The actuator 150 receives a drive signal from the control unit 190 and opens and closes the wire cutter 200, the first clamper 131, and the second clamper 132, or displaces other elements.

[0026] The procedure for forming a pin wire 310 on a target pad electrode 321 using a bonding apparatus 100 having the above configuration will now be described. Figure 4 is a process diagram showing the procedure for forming the pin wire 310. Figures 4(a) to 4(i) are arranged in the order of the process, and will be explained in that order below. Note that each figure in Figure 4 is a schematic representation of the main parts extracted from the view from direction A shown in Figure 2.

[0027] Figure 4(a) shows the initial state of the process, where the wire 300 has been unfurled from the tip of the capillary 112 by a set amount. The control unit 190 keeps the first clamper 131 in a gripping state (holding the wire 300) so that the unfurled wire is not pulled back by a tensioner (not shown).

[0028] Next, as shown in Figure 4(b), the control unit 190 applies a voltage to the torch 111 to generate an arc discharge between the electrode and the wire tip, thereby creating FAB300a. Once FAB300a is generated, the control unit 190 transitions the first clamper 131 from a gripping state to a disengaged state (a state in which the wire 300 is released), as shown in Figure 4(c).

[0029] The control unit 190 displaces the slide mechanism 123 to insert the notched portion 210 and the receiving portion 220 into the unfurled wire 300 from the horizontal direction, and as shown in Figure 4(d), operates the actuator 150 to bring the notched portion 210 and the receiving portion 220 closer together and close them to each other.

[0030] The control unit 190 then operates the actuator 150 to separate the notch 210 and the receiving part 220, as shown in Figure 4(g). This continuous movement of the notch 210 and the receiving part 220 forms a notch 300b in the wire 300. Once the formation of the notch 300b is complete, the control unit 190 moves the notch 210 and the receiving part 220 to the standby position.

[0031] Once the notched portion 210 and the receiving portion 220 are moved to the standby position, the control unit 190 drives the actuator 150 that operates the Z rotation mechanism 114, as shown in Figure 4(f), to bring the capillary 112 closer to the FAB 300a, while the second clamper 132 holds the wire 300 and maintains the wire 300 in a stationary state. By bringing the capillary 112 closer to the FAB 300a in this way, even if the wire tail is bent, the insertion hole of the capillary 112 passes over the outer circumference of the wire tail, straightening and correcting the bent portion. The tip of the capillary 112 may be brought close to the FAB 300a with a small gap, or if it is to come into contact with the FAB 300a, the descent speed of the capillary 112 may be reduced just before contact to mitigate the impact on the FAB 300a. In this embodiment, the first clamper 131 also descends along with the descent of the capillary 112.

[0032] Next, as shown in Figure 4(g), the control unit 190 transitions the second clamper 132 to a dissociated state while the first clamper 131 remains dissociated, causing the capillary 112 to descend. When the capillary 112 descends, the FAB 300a is pushed by the tip of the capillary 112 and descends together with it. At this time, since both clampers are dissociated, a new wire 300 is drawn from the wire supply device in accordance with the descent of the FAB 300a. When the FAB 300a reaches the pad electrode 321, the tip of the capillary 112 crushes the FAB 300a against the pad electrode 321. In this state, the control unit 190 vibrates the transducer 113 to fix the FAB 300a to the pad electrode 321.

[0033] Subsequently, as shown in Figure 4(h), the control unit 190 operates the Z rotation mechanism 114 while the first clamper 131 remains disengaged, thereby raising the capillary 112 to a preset height. Then, the first clamper 131 transitions to a gripping state, and as shown in Figure 4(i), the capillary 112 is raised further, causing the wire 300 to break at the cut 300b, and a pin wire 310 to be formed on the pad electrode 321.

[0034] Alternatively, the process shown in Figure 4(e) could be followed by transitioning the first clamper 131 to the dissociated state and initiating the descent of the capillary 112. During the descent, the tip of the capillary 112 could be brought into contact with the FAB 300a, and then, as shown in Figure 4(g), the FAB 300a could be brought into contact with the pad electrode 321. However, since the wire 300 is pulled back when the first clamper 131 is transitioned to the dissociated state by the action of the tensioner, in such a procedure, the impact when the tip of the capillary 112 contacts the FAB 300a would be large, and there is a risk that the molten FAB 300a may be displaced or fall off. Therefore, as explained in the process shown in Figure 4(f), it is desirable to keep the wire 300 stationary and bring the capillary 112 close to the FAB 300a.

[0035] In the above, an embodiment of forming a pin wire 310 using a bonding apparatus 100 has been described. However, using a bonding apparatus 100 with a similar configuration, it is also possible to connect, for example, a pad electrode provided on a semiconductor chip and a lead electrode provided on a substrate with a loop wire. Figure 5 is a process diagram showing the procedure for forming a loop wire according to another embodiment.

[0036] The steps in Figures 5(a) to 5(c) are the same as those in Figures 4(a) to 4(c). When forming a wire loop, the steps in Figures 4(d) and 4(e) for forming the notch 300b are omitted, so the step in Figure 5(d) is performed following the step in Figure 5(c) to lower the capillary 112 and the first clamper 131 toward the FAB 300a. Specifically, the control unit 190 drives the actuator 150 which operates the Z rotation mechanism 114 while the second clamper 132 holds the wire 300 and maintains the wire 300 in a stationary state, bringing the capillary 112 closer to the FAB 300a. Through this step, the bent portion is straightened and corrected into a straight line, as explained in the step in Figure 4(f).

[0037] Next, as shown in Figure 5(e), the control unit 190 transitions the second clamper 132 to a dissociated state while the first clamper 131 remains dissociated, causing the capillary 112 to descend. When the capillary 112 descends, the FAB 300a is pushed by the tip of the capillary 112 and descends together with it. At this time, since both clampers are dissociated, a new wire 300 is drawn from the wire supply device in accordance with the descent of the FAB 300a. When the FAB 300a reaches the pad electrode 321, the tip of the capillary 112 crushes the FAB 300a against the pad electrode 321. In this state, the control unit 190 vibrates the transducer 113 to fix the FAB 300a to the pad electrode 321 (fast bonding).

[0038] Next, as shown in Figure 5(f), the control unit 190 lifts the first clamper 131 and capillary 112, which are still in a dissociated state, and lowers the capillary 112 to press the wire 300 against the lead electrode 322 while forming a loop wire toward the lead electrode 322. After that, the control unit 190 vibrates the transducer 113 to fix the wire 300 to the lead electrode 322 (second bonding).

[0039] In the above, a bonding apparatus 100 has been described in which it is equipped with two clamps, a first clamper 131 and a second clamper 132. However, even if the bonding apparatus is equipped with only one clamper for the wire 300, the FAB 300a can be similarly fixed to the electrode. Figure 6 is a process diagram showing the procedure in the case of another embodiment where there is only one clamper.

[0040] Figure 6(a) shows the initial state of the process, where the wire 300 has been unfurled from the tip of the capillary 112 by a set amount. The control unit 190 keeps the clamper 133 in a gripping state so that the unfurled wire is not pulled back by a tensioner (not shown).

[0041] Next, as shown in Figure 6(b), the control unit 190 applies voltage to the torch 111 to generate an arc discharge between the electrode and the wire tip, creating the FAB 300a. Once the FAB 300a is created, the control unit 190, as shown in Figure 6(c), drives the actuator 150 that operates the Z rotation mechanism 114 while the clamp 133 is still gripping, bringing the capillary 112 closer to the FAB 300a. Through this process, the bent portion is straightened and corrected into a straight line, as explained in the process shown in Figure 4(f).

[0042] Next, as shown in Figure 6(d), the control unit 190 transitions the clamper 133 to a dissociated state and lowers the capillary 112. When the capillary 112 is lowered, the FAB 300a is pushed by the tip of the capillary 112 and lowers together with it. At this time, since the clamper 133 is in a dissociated state, a new wire 300 corresponding to the lowering of the FAB 300a is drawn from the wire supply device. When the FAB 300a reaches the pad electrode 321, the tip of the capillary 112 crushes the FAB 300a against the pad electrode 321. In this state, the control unit 190 vibrates the transducer 113 to fix the FAB 300a to the pad electrode 321. Note that the above steps may be used as part of the process of forming a pin wire or as part of the process of forming a loop wire. [Explanation of symbols]

[0043] 100...Bonding device, 111...Torch, 112...Capillary, 113...Transducer, 114...Z rotation mechanism, 122...Support arm, 123...Slide mechanism, 131...First clamper, 132...Second clamper, 140...Imaging unit, 150...Actuator, 160...XY table, 161...Support base, 170...Stage, 181...Storage unit, 182...Input / output device, 190...Control unit, 200...Wire cutter, 210...Cutting section, 211...Main body, 300...Wire, 300a...Free air ball, 300b...Cutting section, 310...Pin wire, 320...Substrate, 321...Pad electrode, 322...Lead electrode

Claims

1. An actuator moves a capillary through which a wire is inserted in the direction in which the wire is inserted, A clamper that performs a clamping and releasing motion on the aforementioned wire, A torch that forms a free air ball at the tip of the aforementioned wire, The actuator, the clamper, and the control unit that controls the torch Equipped with, The control unit is a bonding apparatus that forms the free air ball with the torch while the wire is clamped by the clamper, operates the actuator to bring the capillary close to the free air ball, operates the actuator to pull the capillary down toward the bonding target while the clamper releases the wire, and presses the free air ball against the bonding target to fix it in place.

2. The clamp includes a first clamp that is movable in the insertion direction and a second clamp that does not move in the insertion direction. The actuator moves the first clamper in the insertion direction, The bonding apparatus according to claim 1, wherein the control unit clamps the wire with the second clamper and the first clamper releases the wire, bringing the capillary close to the free air ball, and with the first clamper and the second clamper released, pulls the capillary downward toward the bonding target.

3. The bonding apparatus according to claim 2, wherein the control unit, together with the capillary, pulls down the first clamp, which has released the wire, toward the bonding target.

4. The wire cutter is provided to form a notch in the wire that is fed out from the capillary, The bonding apparatus according to claim 1, wherein the control unit controls the wire cutter to form the cut in the wire after the free air ball has been formed, and then brings the capillary close to the free air ball.

5. A free air ball forming step involves clamping a wire supplied from a supply device with a clamper and forming a free air ball at the tip of the wire with a torch, A proximity step involves operating the actuator to move the capillary through which the wire is inserted in the insertion direction, bringing it closer to the free air ball, The bonding step involves the clamp releasing the wire, operating the actuator to pull the capillary downward toward the bonding target, and pressing the free air ball against the bonding target to secure it. A method for controlling a bonding apparatus having [a specific feature / feature].

6. A free air ball forming step involves clamping a wire supplied from a supply device with a clamper and forming a free air ball at the tip of the wire with a torch, A proximity step involves operating the actuator to move the capillary through which the wire is inserted in the insertion direction, bringing it closer to the free air ball, The bonding step involves the clamp releasing the wire, operating the actuator to pull the capillary downward toward the bonding target, and pressing the free air ball against the bonding target to secure it. A control program for a bonding device that causes a computer to execute commands.

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