JP7266299B2 - Ultrasonic bonding equipment - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic bonding apparatus used, for example, for wiring connections and connections between metal terminals.

2. Description of the Related Art In recent years, many power devices such as laminated batteries, vehicle motors, and ECUs have been used as vehicle electrical components. These electrical components are often wire-bonded using bonding wires as board connection terminals. A large-diameter bonding wire that allows a large current such as 50 A (ampere) or 100 A to flow is used for the substrate connection terminal. As wiring materials to be joined, a copper wire, a copper plate, a nickel plate, an aluminum wire, an aluminum plate, or the like is used. Resistance welding (spot welding), soldering, ultrasonic bonding, or the like is used as a method for joining the board connection terminals.

Among the above joining methods, if resistance welding is used, the joining portion is likely to be oxidized and heat is generated, so that the semiconductor device cannot be arranged nearby. With solder joints, the reliability of the joints is low, and contact resistance is generated in the joints, making it easy to generate heat when energized.
On the other hand, ultrasonic bonding is attracting attention because it can instantly join metal materials with a processing time of 0.5 seconds, has low contact resistance due to diffusion bonding, and does not easily generate heat even when a large current is applied. It is In ultrasonic bonding, an ultrasonic bonding horn is pressed against the superimposed workpieces, and while a bonding load is applied, ultrasonic vibrations are applied to the ultrasonic bonding section to destroy the oxide film formed on the workpiece surface and clean the workpieces. It produces a metal surface and is bonded by forming an intermetallic compound.

As a method of joining metal materials (workpieces) that are stacked one on top of the other, the lower metal material is fixed with an anvil jig or the like, and the upper metal material is bitten by the teeth of the horn of the ultrasonic welding tool to transmit lateral vibration. . At this time, it is necessary to continuously maintain an appropriate pressing pressure (bonding load) for generating a clean metal surface on the work bonding surface.
If the load is less than the appropriate pressing pressure, even if friction occurs, the frictional force that destroys the oxide film will not be generated, and bonding will not occur.
In addition, when the load is greater than the appropriate pressing pressure, only the frictional force between the metal materials increases, and friction does not occur on the joint surface, and as a result, the teeth of the ultrasonic horn crush or crush the upper metal material. Energy is used to deform the workpiece, such as squeezing, resulting in a product that is not joined even if the crushed distance and outer shape are the same.

The appropriate pressing pressure varies depending on many factors, such as the state of the oxide film on the work surface, the hardness of the material, and the mass of the material to be vibrated. Optimal values are obtained through experiments by changing the sound wave output, load, and time. Thus, in metal joining, control to keep the load constant is important. In addition, since the power required for ultrasonic bonding changes due to changes in the load, it is important to apply a load that does not fluctuate.

The following techniques have been proposed as joining techniques in which a predetermined load is applied to the work. A pressing force profile of the bumps of the IC chip and the electrodes of the circuit board is created in advance. A load cell detects the pressure applied to the suction collet for a certain period of time from the contact between the bump and the electrode to the completion of bonding. By dividing the difference in the amount of displacement by the difference between the current time and the remaining time until the completion of welding, the corrected movement speed of the suction collet is obtained, and by controlling the motor rotation speed, the target pressing force is achieved at the time of completion of welding. (Patent Document 1: JP-A-2003-318226).
In addition, an elevating unit that supports the crimping head so that it can move vertically, a load cell that is interposed between the crimping heads and detects the load acting on the crimping head, and a coil spring that has linear load/displacement characteristics with the load cell are arranged in series. A thermocompression bonding apparatus has been proposed in which the amount of displacement of the load cell is increased and the amount of change in the pressing load per unit lifting operation is reduced by arranging the load cells in combination with each other (Patent Document 2: Japanese Patent Application Laid-Open No. 2007-335894).
In addition, a spring pressurization type joining device has been proposed in which the pressurizing force of an air actuator and the repulsive force of a repulsive force setting spring are serially cooperated and applied to the joining head (Patent Document 3: Japanese Patent Application Laid-Open No. 2016-107279). ).

JP-A-2003-318226 JP 2007-335894 A JP 2016-107279 A

For example, when connecting an aluminum wire with a diameter of 8 mm (38 sq: core wire cross-sectional area) to a metal terminal, the finished height is approximately 3 mm. This means that the horn descends by about 5 mm during the ultrasonic oscillation operation for 1 to 2 seconds, so if the bonding load cannot be maintained following the descending speed of 5 mm/sec, the applied load value will decrease. .

When the joint load is detected using the compression coil spring of Patent Document 1, the spring coefficient changes greatly due to temperature changes. When the moving speed of the suction collet is controlled by a servomotor, when torque is applied from the outside, the collet deviates from the positioned point, so the set bonding load changes and the amount of positional deviation also changes. Therefore, the target position cannot be tracked unless the gain is increased to improve the response. If the position gain is set high, it becomes easy to oscillate, which increases the possibility of causing vibration. In addition, a motor with a large output is required, and the starting speed becomes slow, so it is not suitable for rapid start-up.
When the joint load is detected by a load cell as in Patent Document 2, an integration circuit is provided in the amplifier to remove noise on the analog signal input to the load cell, so the response of the output signal is slow and sudden changes cannot be detected. . As a result, the up-and-down control of the crimping head is delayed with respect to the load fluctuation.
When pressure is applied using both an air actuator (air cylinder) and a spring as in Patent Document 3, when the machining distance is as large as 5 mm, the cylinder cannot follow the expansion and contraction of the spring due to a sudden change in load. The spring expands and the pressure temporarily drops. Therefore, control to maintain a constant bonding load is not possible.

The present invention has been made to solve these problems, and its object is to perform a constant load control with good responsiveness when superimposing and ultrasonically bonding metal materials to improve processing accuracy. An object of the present invention is to provide an improved ultrasonic bonding apparatus.

In order to achieve the above objects, the present invention has the following configurations.
An ultrasonic bonding apparatus that superimposes workpieces made of metal materials and bonds them by ultrasonically vibrating them while a bonding tool is pressed against the workpieces. A motor, a drive transmission mechanism that converts the rotational drive of the pulse motor into a linear motion, and a drive transmitted by the drive transmission mechanism to vertically move up and down along a first linear motion rail provided on the standing portion. a first moving portion, a second moving portion that reciprocates in the vertical direction along a second linear motion rail provided on the first moving portion and holds the welding tool, and a second moving portion that lowers the first moving portion. a load detection unit that detects a bonding load that becomes a target load value by pressing the welding tool against the work by elastically deforming an elastic member interposed between the first moving portion and the second moving portion; , a linear scale for measuring the amount of vertical movement of the second moving part with respect to the first moving part; and a control part for controlling the operation of the pulse motor, wherein the control part controls the first moving When the welding tool is pressed against the workpiece and the welding load value detected by the load detection unit reaches a target load value, the welding tool is ultrasonically vibrated to move the welding tool to the first moving portion. By measuring the displacement of the second moving part in the vertical direction from the change in the measurement value of the linear scale and driving the pulse motor to rotate in a predetermined direction with predetermined pulses to move the first moving part, the joint load is It is characterized in that the load is controlled so as to keep the value at a predetermined value.

According to the above configuration, the control unit sets the target load value by the load detection unit, ultrasonically vibrates the welding tool, detects the vertical positional deviation of the second moving unit with respect to the first moving unit by the linear scale, By rotating the pulse motor in a predetermined direction with a predetermined pulse to move the first moving portion, the load is controlled so as to keep the bonding load value at a predetermined value. Therefore, since the response of the linear scale is high-speed, even if there is a sudden change in the joint load acting on the workpiece, the response can be improved by rotating the pulse motor in a predetermined direction in a predetermined pulse according to the measurement value of the linear scale. Ultrasonic bonding can be performed with good constant force control.
In particular, compared to load control using coil springs, whose spring constant changes or deteriorates due to temperature changes, or load control using load cells, which have a slow response speed to load changes, constant load control with good responsiveness is possible. can be realized.
Although an elastic member is interposed between the first moving part and the second moving part, it is compressed in a state of zero load, and the spring constant with temperature change does not affect load control. In addition, since a linear region of elastic deformation is used within the range used as the joint load, it does not affect load control.

When the second moving portion is displaced downward with respect to the first moving portion, the control portion rotates the pulse motor in a predetermined direction to lower the first moving portion, thereby moving the first moving portion downward. When the second moving portion is displaced upward with respect to, it is preferable that the control portion rotates the pulse motor in the opposite direction to raise the first moving portion to perform load control.
As a result, it is possible to perform constant load control with good responsiveness according to fluctuations in the joint load with respect to the target load value.

When the measured value of the linear scale exceeds a predetermined pulse range plus or minus a target number of pulses corresponding to the target value load value, the control unit rotates the pulse motor in a predetermined direction to perform load control. can be
As a result, it is possible to perform stable load control by providing an uncontrolled region (buffer region) above and below the target pulse number in consideration of the vibration of the linear scale through the second moving body due to the ultrasonic vibration of the welding tool. can.

The elastic member is a coil spring, the first moving part is provided with position sensors for detecting the upper limit position and the lower limit position of the second moving part, and when the position sensor detects the movement of the second moving part, the It is desirable that the controller stop the output of the pulse motor.
As a result, when the load applied by the vertical movement of the second moving part with respect to the first moving part changes and the deflection amount of the coil spring changes, the deflection amount of the coil spring changes linearly from 30% to 70% of the total deflection amount. Ultrasonic bonding operations can be avoided when loads exceeding the % range are applied.

It is possible to provide an ultrasonic bonding apparatus that performs constant load control with good responsiveness and improves processing accuracy when superimposing and ultrasonically bonding metal materials.

It is a model explanatory view of an ultrasonic bonding apparatus. It is a model explanatory view explaining a pressurization principle. FIG. 3 is a schematic explanatory view showing the principle of pressurization continued from FIG. 2; FIG. 4 is a table and a graph showing measured values of a load cell (load cell 1) and a measuring load cell (load cell 2) when the compression distances of the first coil spring and the second coil spring are changed in units of 1 mm. It is a photograph figure which shows the joining state of an aluminum electric wire and a copper terminal.

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of an ultrasonic bonding apparatus according to the present invention will be described below with reference to the accompanying drawings. The ultrasonic bonding apparatus superimposes workpieces made of metal materials, and ultrasonically bonds the workpieces by vibrating them with an ultrasonic bonding portion while pressing the ultrasonic bonding tool against the workpieces. As the work, for example, a copper electric wire, an aluminum electric wire, or the like used for a connection portion of a high-current wiring is superimposed on a copper plate, a nickel plate, an aluminum plate, or the like, and used for ultrasonic bonding.

A configuration example of an ultrasonic bonding apparatus will be described with reference to FIG.
A terminal fixing jig 1a (such as an anvil jig) for fixing a copper terminal W1, which is a work, is mounted on the base portion 1. As shown in FIG. The upper surface of the terminal fixing jig 1a is knurled to a thickness of about 0.5 mm, for example, to prevent the terminals from slipping. A pulse motor 3 is supported at the upper end of an apparatus main body 2 (upright portion) formed on the base portion 1 with its motor shaft (not shown) directed vertically downward. As the pulse motor 3, a pulse motor capable of rotating in forward and reverse directions is used. A rolled ball screw 4 is connected to the motor shaft of the pulse motor 3 . A nut 5 is threaded onto the rolled ball screw 4 to convert the rotational drive of the pulse motor 3 into linear motion (drive transmission mechanism).

The nut 5 is integrally attached to the first plate 6 (first moving portion). A first direct-acting guide rail 2a is provided in the device main body 2 in the longitudinal direction (vertical direction). The first plate 6 is linked with the first linear motion guide rail 2a via the first linear motion guide 6a. When the rolled ball screw 4 rotates in a predetermined direction, the nut 5 and the first plate 6 move up and down along the first direct-acting guide rail 2 a provided in the device main body 2 . Since the rolled ball screw 4 is a right-hand screw, the first plate 6 descends when rotated in the CW direction (clockwise direction), and the first plate 6 ascends when rotated in the CCW direction (counterclockwise direction).

A second plate 7 (second moving portion) is attached to the first plate 6 so as to reciprocate in the vertical direction. A horn clamp 7a is provided at the lower end of the second plate 7, and an ultrasonic horn 8 (welding tool) is held by this horn clamp 7a. The first plate 6 has a first spring attachment portion 6b and a second spring attachment portion 6c at two positions in the vertical direction, which project in the horizontal direction. A pair of second direct-acting guide rails 6d are vertically provided on the first and second spring mounting portions 6b and 6c. The second direct-acting guide rails 6d may be provided vertically on the first plate 6 on both sides of the first and second spring mounting portions 6b and 6c. The second plate 7 is linked with the second direct-acting guide rail 6d through the second direct-acting guide 7b. The ultrasonic horn 8 ultrasonically joins by ultrasonically vibrating the vibrator 8b with the ultrasonic oscillator 9 while the tip 8a of the horn is in contact with the aluminum wire W2 placed on the copper terminal W1. there is A horn tip portion 8a of the ultrasonic horn 8 is knurled or corrugated on the surface to be pressed against the aluminum electric wire W2.

Further, the second plate 7 is provided with an intermediate plate 7c which is inserted between the first spring mounting portion 6b and the second spring mounting portion 6c so as to protrude in the horizontal direction. A load cell 10 (load cell 1: load detector) is fixed on the intermediate plate 7c. A first coil spring 11 (coil spring) is extendably provided between the first spring mounting portion 6b and the load cell 10, and a second coil spring is provided between the intermediate plate 7c and the second spring mounting portion 6c. A spring 12 (coil spring) is provided so as to be able to expand and contract.

The second plate 7 moves up and down together with the first plate 6 due to the rotation of the rolled ball screw 4, and when the ultrasonic horn 8 held by the second plate 7 is pressed against the work, it moves up relatively to perform ultrasonic bonding. When the thickness of the work decreases, it descends.
By lowering the first plate 6 and elastically deforming the first coil spring 11 and the second coil spring 12 (elastic members) interposed between the first plate 6 and the second plate 7, the ultrasonic horn 8 is moved. The load cell 10 is pressed against the workpiece to detect the joint load that becomes the target load value.

Further, the first plate 6 is provided with a linear scale 13 for measuring the vertical positional displacement of the second plate 7 with respect to the first plate 6 . In this example, as will be described later, the joint load of the ultrasonic horn 8 is controlled based on the detection signal of the linear scale 13 rather than the detection signal of the load cell 10 . As the linear scale 13, for example, an optical reflection incremental type is used.

A control device 14 (controller: controller) controls the bonding operation of the ultrasonic horn 8 and the drive of the pulse motor 3 . The control device 14 includes a CPU (Central Processing Unit) that controls the operation of the entire device, a ROM that stores control programs, reads control programs stored in the ROM, performs calculations as a work area of the CPU, and inputs It includes a RAM for temporarily storing data input from an operation panel or the like, a motor driver 14a for driving and controlling the pulse motor 3, and the like.
An input signal input from an input unit (not shown), a load value detected by the load cell 10, and a displacement measurement value (counter value) detected by the linear scale 13 are input to the control device 14. A drive signal for the pulse motor 3 and a drive signal for the ultrasonic oscillator 9 are sent.
The control device 14 stores the target load value detected by the load cell 10 in advance, activates the ultrasonic oscillator 9 in response to a command from the input unit, and operates the pulse motor 3 in response to the displacement detection value of the linear scale 13. is rotated in a predetermined direction by a predetermined amount to control the joint load to a target load value.

The controller 14 detects a state in which the first plate 6 is lowered, the horn tip 8a of the ultrasonic horn 8 is pressed against the workpiece (aluminum electric wire W2), and the load value detected by the load cell 10 reaches the target load value. Then, the ultrasonic horn 8 is ultrasonically vibrated, the positional displacement of the second plate 7 in the vertical direction with respect to the first plate 6 is measured from the change in the measurement value of the linear scale 13, and the pulse motor 3 is rotated in a predetermined direction by a predetermined pulse. The first plate 6 is moved by driving. Thereby, load control is performed so that the displacement amount (deflection amount) of the first coil spring 11 and the second coil spring 12 is kept within a predetermined range.

Here, the pressurizing principle for keeping the bonding load constant will be described with reference to FIGS. 2 to 4. FIG. In FIG. 2, the terminal fixing jig 1a is provided with a measuring load cell 15 (load cell 2). When the pulse motor 3 is rotationally driven to lower the first plate 6 along the device main body 2 , the leading end (lower end) of the second plate 7 hits the measuring load cell 15 . When the first plate 6 is further lowered, the first coil spring 11 is compressed and the second coil spring 12 is extended. From this state, the values of the load cell 10 (load cell 1) and the measuring load cell 15 (load cell 2) when the amount of change in compression or elongation of the first coil spring 11 and the second coil spring 12 is changed in units of 1 mm are It is shown in the table of FIG. 4A and the graph of FIG. 4B.
As a method of converting the value of the load cell 1 to the value of the load cell 2 (applied load value), when the horn tip 8a is separated from the load cell 15 for measurement, the spring compression distance position where the load cell 2 indicates zero. Use the value of load cell 1 as the shift value (150N). The inclination of the load cell 1 when the first plate 6 is lowered until the load cell 2 indicates, for example, 500N is obtained. If the tilt of load cell 1 is a1 and the tilt of load cell 2 is a2, the tilt magnification is a2/a1, and the load conversion formula subtracts the shift value from the value of load cell 1 and multiplies the tilt magnification. In FIG. 4B, the shift value is 150 N, so if the value of load cell 1 is F1, to convert the applied load value of load cell 2 to F2,
F2 = (F1 - 150N) x (a2/a1).

When the amount of deflection (compression distance) of the first coil spring 11 and the second coil spring 12 is converted into a load, it must be used within the range of 30% to 70% of the total amount of deflection in design. . This is because the area where the spring constant shows a straight line is small at 30% or less and large at 70% or more. In this embodiment, the first plate 6 is provided with a pair of position sensors 16 (for example, photo sensors) that extend beyond the use area (upper end and lower end) of the spring, and the second plate 7 is detected by any of the position sensors 16. Then, the output to the pulse motor 3 is cut off.
In addition, the first coil spring 11 and the second coil spring 12 are both compressed in a zero load state, and are designed to use a linear region of the spring constant within the load range used in the device. The first plate 6 may be provided with a load adjusting screw for adjusting the amount of deflection of the first coil spring 11 in advance.

Next, a bonding operation using the ultrasonic bonding apparatus described above will be described.
As shown in FIG. 1, an aluminum electric wire W2 is placed on a copper terminal W1 set on a terminal fixing jig 1a, and a downward load is applied by a horn tip portion 8a. The load value is a value obtained by calculating the load value measured by the load cell 10 (load meter 1) as described above, and is the same value as the applied load value. When the pulse motor 3 is rotated in the CW direction (clockwise direction) until the pressurized load value reaches the target load value (for example, 500 N), the first plate 6 descends and the horn tip 8a hits the aluminum wire W2. The second plate 7 slides on the second direct-acting guide rail 6d linked with the first plate 6, and the relative position with the first plate 6 is shifted. At this time, the first coil spring 11 is compressed and the second coil spring 12 is extended. After the aluminum wire W2 is crushed by the load applied by the horn tip portion 8a, the first plate 6 does not descend any further. When the relative position between the first and second plates 6 and 7 is displaced, an output pulse of the linear scale 13 is sent to change the counter value. For example, assuming that the pulse motor 3 has 500 pulses per rotation of 0.72°/pls and the lead of the rolled ball screw 4 is 2 mm, 250 pulses move 1 mm, or 0.004 mm per pulse.

When the load value detected by the load cell 10 reaches the target load value (for example, 500 N) and the distance over which the aluminum wire W2 is crushed by the load does not change, the controller 14 controls the counter detected by the linear scale 13. Set the value as the target number of pulses, and execute the following control. When the relative position between the first plate 6 and the second plate 7 shifts, a pulse is generated every 0.001 mm from the linear scale 13. This pulse is divided by (1/4) and applied to the motor driver 14a. (It becomes a pulse equivalent to 0.004 mm). When the output pulse of 0.001 mm/pls from the linear scale 13 is divided by (1/4), the result is 0.004 mm/pls. can be controlled so as not to cause any deviation.

When the second plate 7 is displaced downward (in the direction of decreasing pressure) with respect to the first plate 6, the controller 14 deviates from the target number of pulses in the negative direction. ) to lower the first plate 6 . Further, when the second plate 7 is displaced upward (in the direction in which the pressure increases) with respect to the first plate 6, the controller 14 deviates from the target number of pulses in the positive direction. A predetermined pulse is applied in the counterclockwise direction) to raise the first plate 6 .

In this state, the control device 14 causes the ultrasonic oscillator 9 to oscillate so that the horn tip portion 8a is laterally vibrated by the vibrator 8b. Joined to form a compound. The photograph of FIG. 5 shows a state in which the aluminum wire W2 is joined to the copper terminal W1.
At this time, the horn tip portion 8a of the ultrasonic horn 8 descends at a predetermined speed (5 mm/sec), but the linear scale 13 detects the displacement between the first and second plates 6, 7 and outputs an output pulse. However, since the controller 14 controls the drive of the pulse motor 3 from the output pulse, the deviation between the first and second plates 6 and 7 is constant. That is, the joint load value can be kept constant.

When the amount of movement between the plates per pulse of the pulse motor 3 is converted into a load, the spring constant is 64 N/mm, so the load changes by 1N for about 4 pulses (3.9 pulses). This calculation can suppress the load deviation within 0.25 N, but in reality, the mechanical vibration due to the ultrasonic vibration of the ultrasonic horn 8 is transmitted as vibration of the linear scale 13, so the load above and below the target number of pulses Stable constant load control is achieved by providing a buffer area (uncontrolled area) of about ±1N to ±5N in terms of conversion.

Specifically, the number of revolutions that can be started at the self-starting frequency of the pulse motor 3 is 300 rpm, which is 5 revolutions per second. Assuming that the speed at which the motor can rotate is 1/5 of the actual load, it can be considered that the motor can rotate about once per second. Since one rotation of the pulse motor 3 is 500 pulses, converting 500 pulses into a load yields 500/4=125N. When the output pulse of the linear scale 13 is directly input to the motor driver 14a, it is calculated that a load change of 125 N per second can be followed. Since the descending speed of the ultrasonic horn 8 is 5 mm/sec, it rotates 2.5 times per second. However, since the magnification is low, it can be seen that it is feasible. If the load drops by 1 N at the initial stage when the load drops, adding 4 pulses can prevent the load from dropping. If the detection signal of the linear scale 13 is directly connected to the motor driver 14a, the motor can be controlled from one pulse, and the load reduction can be eliminated. deflection, backlash of the direct-acting guide, etc., the load value fluctuates. In order to solve this problem, vibration can be suppressed by setting a non-operating band of about ±several pulses (±4 pulses to 20 pulses) to the target number of output pulses of the linear scale 13. FIG.

Also, the horn clamp 7a that supports the ultrasonic horn 8 is desirably designed to have a large mass. Since the ultrasonic horn 8 vibrates laterally during processing, the vibration energy is lost if the mass of the parts supporting it is small. However, if the horn clamp 7a is designed to be heavy, it will move a heavy-mass component at high speed, requiring a motor output. If it is within the pullout torque of the pulse motor 3, the starting thrust will not run short. In order to avoid resonance, each component of the ultrasonic bonding apparatus must be designed with dimensions that avoid (1/2)λ (approximately 75 mm at 35 kHz and approximately 125 mm at 40 kHz) of the natural frequency of the horn.

In the above-described embodiment, the target load value is designed to be 500 N, but the target load value is not limited to this. Alternatively, the spring constant of the coil spring may be changed to a larger one to perform highly accurate control with a heavier load. Also, although the case of joining the aluminum wire W2 to the copper terminal W1 has been illustrated, it may be used for ultrasonic joining of other works such as joining a copper wire to a copper terminal or a nickel terminal.

As described above, the pulse motor 3 is rotated by a predetermined pulse in a predetermined direction in accordance with the measurement value of the linear scale 13 even for a sudden change in the bonding load acting on the workpiece. Controls can be applied to effect ultrasonic bonding.
In particular, load control with better responsiveness is achieved compared to load control using coil springs, whose spring constant changes or deteriorates due to temperature changes, or load control using load cells, which have a slow response speed to load changes. can do.

REFERENCE SIGNS LIST 1 base portion 1a terminal fixing jig W1 copper terminal W2 aluminum wire 2 device body portion 2a first linear motion guide rail 3 pulse motor 4 rolled ball screw 5 nut 6 first plate 6a first linear motion guide 6b first spring attachment Part 6c Second spring attachment part 6d Second linear motion guide rail 7 Second plate 7a Horn clamp 7b Second linear motion guide 7c Intermediate plate 8 Ultrasonic horn 8a Horn tip 8b Transducer 9 Ultrasonic oscillator 10 Load cell 11 First Coil spring 12 Second coil spring 13 Linear scale 14 Control device 14a Motor driver 15 Measurement load cell 16 Position sensor

Claims (4)

An ultrasonic bonding device that superimposes workpieces made of metal materials and bonds them by ultrasonically vibrating them while a bonding tool is pressed against the workpieces,
a pulse motor supported by an upright portion formed upright from a base portion;
a drive transmission mechanism that converts the rotational drive of the pulse motor into linear motion;
a first moving part that is driven and driven by the drive transmission mechanism and moves up and down in a vertical direction along a first direct-acting rail provided on the standing part;
a second moving part that reciprocates in the vertical direction along a second linear motion rail provided in the first moving part and holds the welding tool;
By lowering the first moving part and elastically deforming an elastic member interposed between the first moving part and the second moving part, the welding tool is pressed against the workpiece to achieve a target load value. a load detection unit that detects a load;
a linear scale for measuring a vertical displacement of the second moving part with respect to the first moving part;
a control unit that controls the welding operation of the welding tool and the drive of the pulse motor;
The control section moves the welding tool using ultrasonic waves in a state in which the first moving section descends, the welding tool is pressed against the workpiece, and the welding load value detected by the load detecting section reaches a target load value. By vibrating, the positional deviation of the second moving part in the vertical direction with respect to the first moving part is measured from a change in the measurement value of the linear scale, and the pulse motor is driven to rotate in a predetermined direction with predetermined pulses to move the first moving part. An ultrasonic bonding apparatus characterized in that by moving a part, load control is performed so as to keep a bonding load value at a predetermined value. When the second moving portion is displaced downward with respect to the first moving portion, the control portion rotates the pulse motor in a predetermined direction to lower the first moving portion, thereby moving the first moving portion downward. 2. The load control according to claim 1, wherein when the second moving part is displaced upward with respect to the Ultrasonic bonding equipment. When the measured value of the linear scale exceeds a predetermined pulse range plus or minus a target number of pulses corresponding to the target value load value, the control unit rotates the pulse motor in a predetermined direction to perform load control. 3. The ultrasonic bonding apparatus according to claim 1 or 2. The elastic member is a coil spring, the first moving part is provided with position sensors for detecting the upper limit position and the lower limit position of the second moving part, and when the position sensor detects the movement of the second moving part, the 4. The ultrasonic bonding apparatus according to any one of claims 1 to 3, wherein the controller stops the output of the pulse motor.

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