JP4064366B2 - Ultrasonic flip chip bonding apparatus and bonding method - Google Patents

Description

  The present invention relates to an ultrasonic flip-chip bonding apparatus and a bonding method for applying ultrasonic vibration when a semiconductor chip and a circuit board are flip-chip bonded.

  Conventionally, for example, as a method of mounting a semiconductor chip on a circuit board or package, there is a wire bonding bonding method for obtaining electrical connection by bonding both ends of an ultrafine wire to an electrode of a semiconductor chip and an electrode or package of the circuit board. In recent years, flip chip bonding methods with higher production efficiency have been used.

  The flip chip bonding method is a mounting method in which an electrode of a semiconductor chip and an electrode such as a circuit board are bonded by a bump which is a conductive connecting member. As this bump, a gold (Au) ball bump, which is relatively easy to form, is widely used. The flip chip bonding method can collectively bond a plurality of bonding points via bumps, so that the production efficiency is basically higher than that of the wire bonding bonding method in which bonding points are bonded one by one with a fine wire in order. Has the advantage of high. Further, in the flip chip bonding method, since the arrangement of the electrodes that are the bonding terminals is not limited to the periphery of the semiconductor chip, the number of bonding terminals can be greatly increased, and the mounting area of the semiconductor chip can be reduced, Also, the wiring length of the circuit can be shortened. Therefore, the flip chip bonding method is suitable for high-density mounting, high-speed semiconductor chip mounting, and the like.

  Specific methods of this flip chip bonding method include a method of bonding bumps and circuit board electrodes via an intermediate material such as a conductive paste, a method of directly bonding by thermocompression bonding or ultrasonic thermocompression bonding, etc. There is. The latter direct bonding method can be omitted because it can save the intermediate material, has a small number of steps, and the combined ultrasonic method has the advantage that the bonding time can be shortened. Yes.

  FIG. 7 is a side view showing a simplified configuration near a bonding tool in a conventional ultrasonic flip-chip bonding apparatus. FIG. 7 shows a bonding tool 3 that sucks the semiconductor chip 2 on which the bumps 1 are provided, and a circuit board 4 that faces the semiconductor chip 2 that is sucked by the bonding tool 3.

  The semiconductor chip 2 sucks the air from the suction hole in which an opening is formed in the lower surface of the bonding tool 3 and is held by the bonding tool 3 by the vacuum suction force by this suction. The bonding tool 3 is aligned with the circuit board 4 so that the bumps 1 provided on the semiconductor chip 2 correspond to the electrodes 5 formed in advance on the surface of the circuit board 4 facing the semiconductor chip 2. . Next, the bonding tool 3 is lowered toward the circuit board 4, the bumps 1 provided on the semiconductor chip 2 are pressed against the electrodes 5 of the circuit board 4, and ultrasonic vibration is applied to the semiconductor chip 2 via the bonding tool 3. Then, the bumps 1 of the semiconductor chip 2 and the electrodes 5 of the circuit board 4 are joined.

  During this bonding operation, the horizontal component of the holding force of the semiconductor chip 2 by the bonding tool 3 is a load that presses the semiconductor chip 2 against the circuit board 4 by the bonding tool 3 and the semiconductor chip 2 is attracted by the bonding tool 3. This is a frictional force generated on the contact surfaces of the bonding tool 3 and the semiconductor chip 2 based on the vacuum suction force.

  Since the semiconductor chip 2 does not vibrate itself and vibrates following the ultrasonic vibration of the bonding tool 3, the semiconductor chip 2 has a higher frictional force than the friction force at the contact surface between the bonding tool 3 and the semiconductor chip 2. If the frictional force at the contact surface between the bump 1 and the electrode 5 of the circuit board 4 is larger, the semiconductor chip 2 cannot follow the ultrasonic vibration of the bonding tool 3, and the semiconductor chip 2 and the bonding tool 3 A slip phenomenon occurs on the contact surface. When such a slip phenomenon occurs, the ultrasonic vibration applied to the bonding tool 3 is not sufficiently transmitted to the contact surface between the bump 1 and the electrode 5, so that the bonding between the bump 1 and the electrode 5 is insufficient. There is a problem of becoming. If the application time of ultrasonic vibration is increased to obtain sufficient bonding strength, there is a problem that the semiconductor chip is damaged by excessive ultrasonic vibration energy.

  One conventional technique for solving such a problem is to suppress a slip phenomenon between a bonding tool and a semiconductor chip (see, for example, Patent Document 1). FIG. 8 is a partial cross-sectional view showing a simplified configuration in the vicinity of a bonding tool in a conventional ultrasonic flip-chip bonding apparatus that suppresses the slip phenomenon.

  In the bonding (suction) tool 6 disclosed in Patent Document 1, a truncated pyramid-shaped recess 8 is formed on the end surface of the IC chip 7 on the suction side. Therefore, the recess 8 is formed with inner side surfaces called chamfered portions 9a and 9b that are opposed to each other and form a taper. When the IC chip 7 is sucked by the bonding tool 6, the corners 7a and 7b of the IC chip 7 and the chamfered portions 9a and 9b of the bonding tool 6 are held so as to contact each other. Next, the bump 10 provided on the IC chip 7 and the electrode 12 formed on the substrate 11 are aligned and brought into contact with each other, and ultrasonic vibration is applied through the bonding tool 6 to be bonded. At this time, since the IC chip 7 is held by the chamfered portions 9 a and 9 b of the bonding tool 6, the sliding phenomenon between the bonding tool 6 and the IC chip 7 is prevented.

  However, the conventional technique disclosed in Patent Document 1 has the following problems. According to the bonding tool 6, the contact area between the bonding tool 6 and the IC chip 7 is small, and the load and ultrasonic vibration applied at the time of bonding are concentrated on the corners 7 a and 7 b of the IC chip 7. As a result, cracks occur in the corner portions 7a and 7b of the IC chip 7.

JP 2001-127114 A

  An object of the present invention is to provide an ultrasonic flip-chip bonding apparatus and a bonding method capable of efficiently transmitting ultrasonic vibration from a bonding tool to a semiconductor chip and obtaining excellent bonding strength without damaging the semiconductor chip. Is to provide.

The present invention provides an ultrasonic flip chip bonding apparatus that applies ultrasonic vibration to bond a semiconductor chip to a circuit board.
A table on which a circuit board is held and movable in at least one axis direction;
A bonding tool provided to be movable so as to be close to and away from the circuit board held on the table;
A suction means for sucking the semiconductor chip to the bonding tool by sucking the semiconductor chip;
Ultrasonic vibration applying means for applying ultrasonic vibration to the bonding tool;
Amplitude detecting means for detecting the amplitude of vibration of the semiconductor chip;
The ultrasonic flip-chip bonding apparatus includes pressure detection means for detecting suction pressure at which the semiconductor chip is sucked by the bonding tool by the suction means.

Further, the present invention responds to the detection outputs of the amplitude detection means and the pressure detection means,
Stop the suction of the semiconductor chip by the suction means to release the suction state,
It further includes control means for controlling the bonding tool to move in a direction away from the circuit board held by the table.

Further, the present invention provides an ultrasonic flip chip bonding method in which ultrasonic vibration is applied to bond a semiconductor chip to a circuit board.
Hold the circuit board on a table movable in at least one axis direction,
The semiconductor chip is adsorbed to a bonding tool that is movably provided so as to move away from the circuit board held on the table,
Move the bonding tool so that it is close to the circuit board, and contact the semiconductor chip adsorbed by the bonding tool to the circuit board.
Apply ultrasonic vibration to the bonding tool,
Detecting the vibration amplitude of the semiconductor chip and the suction pressure at which the semiconductor chip is attracted to the bonding tool,
When the detected amplitude is equal to or less than a predetermined value and the detected suction pressure is equal to or greater than a predetermined value,
Release the adsorption state between the bonding tool and the semiconductor chip,
An ultrasonic flip-chip bonding method characterized by moving a bonding tool in a direction away from a circuit board.

  According to the present invention, when the semiconductor chip and the circuit board are bonded while applying ultrasonic vibration, the vibration amplitude of the semiconductor chip can be detected, and the suction pressure at which the semiconductor chip is adsorbed by the bonding tool is reduced. Since it can be detected, it is possible to accurately grasp the level of vibration energy applied between the bumps of the semiconductor chip and the electrodes of the circuit board. This improves the reproducibility of efficient ultrasonic vibration transmission from the bonding tool to the semiconductor chip, and makes it possible to stably obtain excellent bonding strength between the semiconductor chip and the circuit board. In addition, by detecting the vibration state of the semiconductor chip during bonding and performing appropriate processing, it becomes possible to perform good manufacturing quality control in the semiconductor chip mounting process, and always maintain the bonding conditions appropriately. As a result, it is possible to suppress the occurrence of defective bonding.

  Further, according to the present invention, it is possible to know the completion time of bonding between the bumps of the semiconductor chip and the electrodes of the circuit board based on the detection outputs of the amplitude detection means and the pressure detection means. That is, when the detected amplitude and the suction pressure change from the initial value of bonding start, for example, exceed a predetermined value, it can be determined that bonding of the bumps of the semiconductor chip and the electrodes of the circuit board is completed. Is possible.

  In response to the detection outputs of the amplitude detection means and the pressure detection means, the suction of the semiconductor chip by the suction means is stopped to release the suction state, and the bonding tool is moved away from the circuit board held on the table. Since the control means for performing control is further provided, the bonding state of the bonding tool that is sucking the semiconductor chip can be released simultaneously with the completion of the bonding between the bumps of the semiconductor chip and the electrodes of the circuit board. As a result, application of excessive ultrasonic vibration to the semiconductor chip can be prevented, so that the semiconductor chip can be firmly bonded to the electrode of the circuit board without damaging the semiconductor chip.

  Furthermore, for example, as described above, by providing a threshold value for the amount of change with respect to the initial value of the start of joining, it is possible to detect the completion of joining. Therefore, it is not necessary to extract the proper joining completion conditions due to product type switching or the like each time. Therefore, improvement in production efficiency is realized.

  Further, according to the ultrasonic flip chip bonding method of the present invention, it is possible to efficiently transmit ultrasonic vibration from the bonding tool to the semiconductor chip without damaging the semiconductor chip, and to obtain excellent bonding strength. .

  FIG. 1 is a system diagram schematically showing the configuration of an ultrasonic flip chip bonding apparatus 20 according to an embodiment of the present invention, and FIG. 2 is a bonding tool 25 provided in the ultrasonic flip chip bonding apparatus 20 shown in FIG. It is a figure which simplifies and shows the surrounding structure. The ultrasonic flip chip bonding apparatus 20 (hereinafter simply referred to as a bonding apparatus 20) is used to bond the semiconductor chip 21 and the circuit board 22 via the bumps 23 by applying ultrasonic vibration.

  The bonding apparatus 20 includes a table 24 that is generally held by a circuit board 22 and movable in at least one axis direction, and a bonding tool that is movably provided so as to be close to and away from the circuit board 22 held by the table 24. 25, suction means 26 for sucking the semiconductor chip 21 to the bonding tool 25 by suction, ultrasonic vibration applying means 27 for applying ultrasonic vibration to the bonding tool 25, and amplitude for detecting the amplitude of vibration of the semiconductor chip In response to the detection means 28, the pressure detection means 29 for detecting the suction pressure at which the semiconductor chip 21 is attracted to the bonding tool 25 by the suction means 26, and the detection output of the amplitude detection means 28 and the pressure detection means 29, the suction means 26 Stops the suction of the semiconductor chip 21 by releasing the suction state, And a control unit 30 for controlling to move in the direction away from the circuit board 22 which is held to 25 in the table 24.

  The semiconductor chip 21 is formed, for example, with a fine circuit on a silicon substrate. A plurality of pads are formed on the surface of the semiconductor chip 21 as connection terminals, and, for example, Au ball bumps 23 are provided in advance on the pads. The circuit board 22 is provided with the same number of electrodes 22 a as the connection terminals corresponding to the pads formed on the semiconductor chip 21 at the mounting position on the surface thereof. The pads formed on the semiconductor chip 21 and the electrodes formed on the circuit board 22 are joined by applying ultrasonic vibration via the Au ball bumps 23.

  The circuit board 22 is held on the table 24 as described above. In the present embodiment, the table 24 is an XY-θ table that is movable in two orthogonal axes and the θ direction. In the paper surface of FIG. 1, the left and right X axis directions and the front and rear Y axis directions , Θ direction. The table 24 moves the circuit board 22 held by the table 24 to a desired position in the XY-θ direction in accordance with an operation control signal giving a coordinate position to be moved from the table control unit 31 connected to the table 24. Can be moved to. The table control unit 31 is a processing circuit that performs overall operation control of the entire bonding apparatus 20, and is electrically connected to the main control unit 30 that functions as the control unit 30. The table control unit 31 controls the operation of the table 24 in accordance with a signal sent from the main control unit 30 based on information such as a camera and an image information processing apparatus.

  The bonding tool 25 is made of, for example, an iron-based material and has a substantially rectangular parallelepiped shape. 2A shows a configuration around the bonding tool 25 in a front view, FIG. 2B shows a bottom view, and FIG. 2C shows a right side view. In FIG. 2B and FIG. 2C, the booster, the ultrasonic horn, and the ultrasonic vibrator are omitted.

  The bonding tool 25 is formed with a first suction hole 33 and second suction holes 34a and 34b so as to open on a lower surface 32 that sucks the semiconductor chip 21, that is, a surface 32 that faces the circuit board 22 held by the table 24. The In the present embodiment, one first suction hole 33 and two second suction holes 34a and 34b are formed.

  The first suction hole 33 is formed so as to have a rectangular opening at a substantially central portion of the lower surface 32. The first suction hole 33 penetrates the bonding tool 25 with the size of the opening, and is connected to a pipe line connected to a suction control unit 49 described later on the opposite side of the opening.

  The second suction holes 34 a and 34 b are formed to have rectangular openings at positions that are symmetric with respect to the first suction hole 33. The second suction holes 34 a and 34 b are formed so that the maximum size of the opening portion opened on the lower surface 32 of the bonding tool 25 is smaller than the minimum size of the surface on which the semiconductor chip 21 is sucked by the bonding tool 25. . In the present embodiment, since the openings of the second suction holes 34a and 34b are formed in a rectangular shape, the maximum dimension thereof is a diagonal dimension. However, since the openings of the second suction holes 34a and 34b are formed in a very long and narrow rectangle, the diagonal dimension is substantially equal to the long side L1 of the rectangle. The semiconductor chip 21 is also formed in a rectangular planar projection shape, and the minimum dimension of the surface attracted by the bonding tool 25 is a rectangular short side L2. Accordingly, the long sides L1 of the openings of the second suction holes 34a and 34b are formed to be smaller than the short sides L2 of the semiconductor chip 21.

  The second suction holes 34a and 34b communicate with the horizontal hole 35 having an opening on the lower surface 32 of the bonding tool 25 and the horizontal hole 35 near the center of the long side L1. And a vertical hole portion 36 formed so as to penetrate through. The vertical hole portions 36 of the second suction holes 34a and 34b are connected to a pipe line connected to a suction control unit 49 described later.

  The first suction holes 33 and the second suction holes 34 a and 34 b are formed as contours of the semiconductor chip 21 on the lower surface 32 where the semiconductor chip 21 contacts the bonding tool 25 in a state where the semiconductor chip 21 is sucked by the bonding tool 25. It is formed so as to open in a region to be defined.

  The adsorption control unit 49 to which the first adsorption hole 33 and the second adsorption holes 34a and 34b are connected by a pipe passes the atmosphere through the first adsorption hole 33 and the second adsorption holes 34a and 34b and the pipe connected thereto. A vacuum pump for suction and a switching operation control unit for controlling an on / off switching operation of the vacuum pump are included. The first suction holes 33 and the second suction holes 34 a and 34 b, the pipelines, and the suction control unit 49 constitute the suction means 26. By operating the suction control unit 49 and sucking air through the first suction holes 33 and the second suction holes 34a and 34b and pipes connected to them, the semiconductor chip 21 accommodated in a chip tray (not shown), for example. Can be picked up from the chip tray by vacuum suction with the bonding tool 25. The adsorption control unit 49 is electrically connected to the main control unit 30 described above.

  The side surface of the bonding tool 25 is connected to ultrasonic horns 37, 38 and boosters 47, 48 that increase and decrease the amplitude of vibration and are fixed to the holder. At least one ultrasonic horn 38 is connected to the booster 48 via the booster 48. An ultrasonic transducer 39 is connected. The ultrasonic transducer 39 is an energy converter such as a piezoelectric element or a magnetostrictive element that converts electrical energy into mechanical energy. A piezoelectric element such as lead zirconate titanate is particularly preferably used for the ultrasonic vibrator. The ultrasonic transducer 39 is electrically connected to the ultrasonic oscillator 40, and generates and outputs ultrasonic vibration of a predetermined frequency in accordance with the power and signal supplied from the ultrasonic oscillator 40. The ultrasonic oscillator 40, the boosters 47 and 48, the ultrasonic transducer 39, and the ultrasonic horns 37 and 38 constitute the ultrasonic vibration applying unit 27. The ultrasonic transducer 39 generates ultrasonic vibration based on the signal from the ultrasonic oscillator 40, and the ultrasonic vibration is transmitted to the bonding tool 25 via the booster 48 and the ultrasonic horn 38, and further the bonding tool. 25 is transmitted to the semiconductor chip 21 attracted to the bonding tool 25, and the semiconductor chip 21 vibrates in the direction of the arrow 41.

  As described above, the joining device 20 according to the present embodiment includes the amplitude detection means 28 and the pressure detection means 29. The amplitude detection unit 28 includes a vibration measurement sensor 42 that detects the vibration of the semiconductor chip 21 and a vibration amplitude measurement unit 43 that measures the amplitude from the vibration detected by the vibration measurement sensor 42. The vibration measurement sensor 42 is realized by, for example, a laser Doppler vibrometer, which is a non-contact vibrometer, receives reflected light of the laser light irradiated on the side surface of the semiconductor chip 21 and changes the frequency of the reflected light due to the Doppler effect. Measure.

  The pressure detection means 29 is a pressure gauge connected to the second suction holes 34a and 34b by a pipe provided separately from the pipe connected to the above-described suction controller 49, and in FIG. Is written. The pressure detection unit 29 sucks air from the second suction holes 34 a and 34 b and measures a suction pressure for sucking the semiconductor chip 21.

  As described above, the semiconductor chip 21 does not vibrate itself, and vibrates following the ultrasonic vibration of the bonding tool 25. Therefore, at a stage where the bump 23 of the semiconductor chip 21 and the electrode 22a of the circuit board 22 are not joined, the semiconductor chip 21 is attracted to the bonding tool 25 and vibrates following the ultrasonic vibration of the bonding tool 25. . However, even at this stage, the vibration amplitude of the semiconductor chip 21 is usually slightly reduced compared to the vibration amplitude of the bonding tool 25 due to friction between the bonding tool 25 and the semiconductor chip 21. .

  When the bonding between the bumps 23 of the semiconductor chip 21 and the electrodes 22a of the circuit board 22 proceeds, the frictional force between the bumps 23 and the electrode 22a exceeds the frictional force between the bonding tool 25 and the semiconductor chip 21. become. At such a stage, since the semiconductor chip 21 does not sufficiently follow the vibration of the bonding tool 25, the vibration amplitude of the semiconductor chip becomes smaller than that at the start of application of ultrasonic vibration.

  On the other hand, the amplitude of vibration of the bonding tool 25 does not change regardless of the bonding stage between the bump 23 and the electrode 22a, so that a slip phenomenon occurs between the bonding tool 25 and the semiconductor chip 21. . When the semiconductor chip 21 slides with respect to the lower surface 32 of the bonding tool 25, the suction to the suction holes by the semiconductor chip 21, particularly the openings of the second suction holes 34a and 34b is broken, so-called leaking. Becomes high (the degree of vacuum is low).

  The amplitude detection means 28 and the pressure detection means 29 can detect such a decrease in the amplitude of vibration of the semiconductor chip 21 and an increase in the suction pressure. For example, in order to bond the semiconductor chip 21 and the circuit board 22, the vibration amplitude and suction pressure of the semiconductor chip 21 at the time when the semiconductor chip 21 is adsorbed by the bonding tool 25 and application of ultrasonic vibration is started are set to the initial values. Set as a value. Next, a rate at which the amplitude of vibration of the semiconductor chip 21 is reduced with respect to the initial value and a rate at which the suction pressure is increased when the proper bonding between the semiconductor chip 21 and the circuit board 22 is completed are obtained. In this way, the reduction ratio of the vibration amplitude of the semiconductor chip 21 and the increase ratio of the suction pressure with respect to the initial value, which are indicators of the completion of bonding, are determined, and when the semiconductor chip 21 and the circuit board 22 are bonded, By detecting the vibration amplitude and suction pressure of the chip 21 in real time and detecting whether or not the set ratio has been reached, it is possible to determine when the semiconductor chip 21 and the circuit board 22 have been joined. become.

  The bonding apparatus 20 is configured to be able to determine the completion of bonding between the semiconductor chip 21 and the circuit board 22. That is, the analog data of the amplitude and pressure detected by the amplitude detecting means 28 and the pressure detecting means 29 is transmitted to the analog / digital (abbreviated as A / D) conversion circuit 44 and converted into digital data. The amplitude and pressure data converted into digital data by the A / D conversion circuit 44 is transmitted to the bonding completion determination unit 45, and the bonding completion determination unit 45 determines whether or not the bonding between the semiconductor chip 21 and the circuit board 22 has been completed. Is done.

  The joining completion determination unit 45 is, for example, an arithmetic circuit. The amplitude and suction pressure of the vibration applied to start bonding of the semiconductor chip 21 and the circuit board 22 are set as initial values, and the ratio of the amplitude and pressure detected during the bonding operation to the initial value is calculated. When the ratio is greater than or less than a predetermined value as a joining completion index, a joining completion signal is transmitted. In addition, the present invention is not limited to this, and when the amplitude and pressure that serve as a bonding completion index are almost constant depending on the type of the semiconductor chip 21, the amplitude and pressure values that serve as the bonding completion index are determined and stored in the memory of the bonding completion determination unit 45 Store and store the difference between the amplitude and pressure detected during the joining operation and a predetermined value. When the deviation is zero (0) or more or zero or less, it is judged that the joining is completed. There may be. A signal sent from the joining completion determination unit 45 is input to the suction control unit 49 and the main control unit 30 and used for operation control of the suction means 26.

  The bonding tool 25, the ultrasonic horns 37 and 38, the boosters 47 and 48, and the ultrasonic transducer 39 described above are supported by the holder 46. A piston rod 52 of a pressure cylinder 51 is attached to the holder 46. The pressure cylinder 51 has a mounting surface opposite to the piston rod 52 attached to the lifting plate 53. The elevating plate 53 is formed with two through holes, and a first guide bar member 54 and a second guide bar member 55 provided to face each other so as to be parallel to each other are inserted into the through holes, respectively. The elevating plate 53 is slidable with respect to the first and second guide rod members 54 and 55 and can move in the vertical direction guided by the first and second guide rod members 54 and 55.

  The first and second guide rod members 54 and 55 are respectively erected on a support frame 56 disposed on the opposite side of the holder 46 with respect to the lifting plate 53. An electric motor 57 is mounted on the extension line of the piston rod 52 of the pressure cylinder 51 in the forward / backward direction, which is substantially in the center of the support frame 56. The electric motor 57 is disposed such that its output shaft 58 faces the lifting plate 53. One end of a male screw member 59 is connected to the output shaft 58 of the electric motor 57. The male screw member 59 is screwed into a nut 60 fixed to the elevating plate 53 and the other end is rotatably supported by the elevating plate 53.

  The electric motor 57 is connected to a motor drive unit 61 that controls the rotation operation, and the motor drive unit 61 is further connected to the main control unit 30 described above. Further, a pressurizing unit 62 is connected to the pressurizing cylinder 51 by a piping system, and a load control unit 63 that controls the pressurizing operation of the pressurizing unit 62 is electrically connected to the pressurizing unit 62, The control unit 63 is connected to the main control unit 30 described above.

  The electric motor 57 is rotationally driven by an operation control signal from the motor drive unit 61, and the male screw member 59 connected to the output shaft 58 is rotated. The rotational movement of the male screw member 59 is converted into the straight movement of the nut 60 to be screwed to the male screw member 59 and the lifting plate 53 to which the nut 60 is fixed, and the lifting plate 53 has the first and second guide rods. It is guided by the members 54 and 55 to move up and down. As the elevating plate 53 moves up and down, the pressure cylinder 51 attached to the elevating plate 53 and the holder 46 attached to the piston rod 52 of the pressure cylinder 51 move up and down.

  In the state where the elevating plate 53 is moved to a desired position as described above, the pressurizing unit 62 is operated according to the control signal from the load control unit 63, and the piston rod 52 of the pressurizing cylinder 51 is moved back and forth. Thus, the holder 46, that is, the bonding tool 25 supported by the holder 46 can be moved close to and away from the circuit board 22 held by the table 24, and the semiconductor chip 21 held by the bonding tool 25 is held by the circuit. The substrate 22 can be pressed.

  The main control unit 30 to which the table control unit 31, the ultrasonic oscillator 40, the adsorption control unit 49, the motor drive unit 61, and the load control unit 63 are electrically connected is, for example, a microcomputer including a central processing unit (abbreviated as CPU). The processing circuit is realized by the above-mentioned, and comprehensively controls the operation of the entire joining apparatus 20 as described above.

  Based on the detection outputs of the amplitude detection means 28 and the pressure detection means 29, when the bonding completion determination unit 45 outputs a signal indicating the completion of bonding between the semiconductor chip 21 and the circuit board 22 to the main control unit 30, the output is output. The received main control unit 30 outputs an operation instruction signal to the suction control unit 49, turns off the vacuum pump of the suction control unit 49, and releases the suction state of the semiconductor chip 21 by the suction means 26. Simultaneously with outputting the operation instruction signal to the suction control unit 49, the main control unit 30 also outputs the operation instruction signal to the load control unit 63, the motor driving unit 61, and the ultrasonic oscillator 40, and the ultrasonic transducer The ultrasonic oscillation of 39 is stopped, the piston rod 52 of the pressurizing cylinder 51 is retracted, the electric motor 57 is rotated in the opposite direction to the above, and the elevating plate 53 is raised. That is, the main control unit 30 releases the adsorbing state between the bonding tool 25 and the semiconductor chip 21 in response to the detection outputs of the amplitude detection unit 28 and the pressure detection unit 29 and moves the bonding tool 25 away from the circuit board 22. It is a control means which controls to move to.

  The adsorption control unit 49 may be configured to turn off the vacuum pump in response to the output signal from the joining completion determination unit 45 regardless of the signal from the main control unit 30. The joining completion determination unit 45 and the main control unit 30 are included.

  FIG. 3 is a flow chart for explaining the ultrasonic flip chip bonding method of the present invention, and FIGS. 4 to 6 are views for explaining the bonding steps of the semiconductor chip 21 and the circuit board 22 corresponding to the flow chart shown in FIG. . The ultrasonic flip chip bonding method of the present invention will be described with reference to FIG.

  In the start step s1, the joining device 20 is prepared, and the circuit board 22 to be joined is held on the table 24 by the transport device. The chip tray is in a state where the semiconductor chip 21 to be bonded to the circuit board 22 is accommodated.

  In step s2, an operation instruction signal is output from the main control unit 30 to the suction control unit 49, and the air is sucked from the first suction holes 33 and the second suction holes 34a and 34b formed in the bonding tool 25 by the suction control unit 49. Then, the semiconductor chip 21 accommodated in the chip tray is sucked and held on the lower surface 32 of the bonding tool 25. Next, for example, according to information from the camera and the image information processing apparatus, the table control unit 31 drives the table 24 by the operation instruction signal of the main control unit 30, and the bumps 23 of the semiconductor chip 21 and the circuit board 22 are driven. Positioning is performed so that the electrodes 22a correspond to each other.

  In step s3, the main control unit 30 outputs an operation instruction signal to the motor driving unit 61 and the load control unit 63, and moves the bonding tool 25 that sucks and holds the semiconductor chip 21 in the direction of the arrow 64 shown in FIG. That is, it is lowered toward the circuit board 22 held on the table 24, and the bumps 23 of the semiconductor chip 21 are pressed against the electrodes 22 a of the circuit board 22. At this time, the force for pressing the semiconductor chip 21 against the circuit board 22 is adjusted by the load control unit 63 controlling the output of the pressurizing unit 62 in accordance with a control signal from the main control unit 30. With the semiconductor chip 21 pressed against the circuit board 22, the circuit board 22 is heated by heat transfer from a heating means (not shown). In a state where the semiconductor chip 21 is pressed against the circuit board 22 and the circuit board 22 is heated, the main control unit 30 outputs a control signal to the ultrasonic oscillator 40 and oscillates ultrasonic vibration to the ultrasonic vibrator 39. Let FIG. 5 shows a state in which a load is applied to the semiconductor chip 21 to press against the circuit board 22 and ultrasonic vibration is applied via the bonding tool 25.

  In step s4, the suction pressure of the semiconductor chip 21 by the suction means 26 (denoted as a degree of vacuum in FIG. 3) is detected by the pressure detection means 29. In step s5, the vibration amplitude of the semiconductor chip 21 is detected by the amplitude detection means 28. To detect. In the flowchart, step s4 and step s5 are described in time series, but these two steps may be performed at the same time, and the order may be reversed. In step s6, it is determined whether or not the amount of decrease in vibration amplitude and the amount of increase in pressure (the amount of decrease in the case of a vacuum level) have reached a predetermined value. This determination is performed in the joining completion determination unit 45. When the determination result is affirmative, the process proceeds to step s7, and when the determination result is negative, steps s4 and s5 are repeated.

  In step s7, the bonding completion determination unit 45 determines the bonding completion of the semiconductor chip 21 and the circuit board 22, and outputs a bonding completion signal from the bonding completion determination unit 45 to the main control unit 30. The control unit 30 outputs an operation instruction signal for turning off the operation of the vacuum pump to the adsorption control unit 49. The suction controller 49 stops the vacuum pump and releases the suction of the semiconductor chip 21 to the bonding tool 25.

  In step s8, as shown in FIG. 6, the ultrasonic oscillator 40 performs ultrasonic oscillation of the ultrasonic transducer 39 in accordance with the operation instruction signal output from the main control unit 30 in response to the output signal from the joining completion determination unit 45. The load control unit 63 retracts the piston rod 52 of the pressurizing cylinder 51, and the motor driving unit 61 rotates the electric motor 57 to raise the elevating plate 53. Then, the process proceeds to step s9, and the semiconductor chip 21 and the circuit board 22 are moved. The joining with is completed. In this way, the semiconductor chip 21 is surface-mounted at the chip mounting position of the circuit board 22.

  Although the present invention is for ultrasonic flip chip bonding of a semiconductor chip to a circuit board, the case where ultrasonic vibration is applied when bonding an electronic component to the circuit board is also included in the scope of the present invention.

It is a systematic diagram which simplifies and shows the composition of ultrasonic flip chip joining device 20 which is one embodiment of the present invention. It is a figure which simplifies and shows the structure around the bonding tool 25 with which the ultrasonic flip chip joining apparatus 20 shown in FIG. 1 is equipped. It is a flowchart explaining the ultrasonic flip-chip joining method of this invention. It is a figure explaining the joining step of the semiconductor chip 21 and the circuit board 22 corresponding to the flowchart shown in FIG. It is a figure explaining the joining step of the semiconductor chip 21 and the circuit board 22 corresponding to the flowchart shown in FIG. It is a figure explaining the joining step of the semiconductor chip 21 and the circuit board 22 corresponding to the flowchart shown in FIG. It is a side view which simplifies and shows the structure of the bonding tool vicinity in the conventional ultrasonic flip chip bonding apparatus. It is the fragmentary figure which simplifies and shows the structure of the bonding tool vicinity in the ultrasonic flip chip joining apparatus of the prior art which suppresses a slip phenomenon.

Explanation of symbols

DESCRIPTION OF SYMBOLS 20 Bonding device 21 Semiconductor chip 22 Circuit board 23 Bump 24 Table 25 Bonding tool 26 Adsorption means 27 Ultrasonic vibration application means 28 Amplitude detection means 29 Pressure detection means 30 Main control part 31 Table control part 33 1st adsorption hole 34a, 34b 1st 2 Adsorption holes 37, 38 Ultrasonic horn 39 Ultrasonic transducer 40 Ultrasonic oscillator 42 Vibration measurement sensor 43 Vibration amplitude measurement unit 44 A / D conversion circuit 45 Joining completion determination unit 46 Holder 47, 48 Booster 49 Adsorption control unit 51 Addition Pressure cylinder 53 Elevating plate 54, 55 Guide rod member 56 Support frame 57 Electric motor 61 Motor drive unit 62 Pressure unit 63 Load control unit

Claims (3)

In an ultrasonic flip chip bonding apparatus that applies ultrasonic vibration to bond a semiconductor chip to a circuit board,
A table on which a circuit board is held and movable in at least one axis direction;
A bonding tool movably provided so as to be close to and away from the circuit board held on the table;
An adsorbing means for adsorbing a semiconductor chip by adsorbing the semiconductor chip;
Ultrasonic vibration applying means for applying ultrasonic vibration to the bonding tool;
Amplitude detecting means for detecting the amplitude of vibration of the semiconductor chip;
An ultrasonic flip-chip bonding apparatus comprising: pressure detection means for detecting suction pressure at which the semiconductor chip is sucked by the bonding tool by the suction means. Responding to the detection output of the amplitude detection means and the pressure detection means,
Stop the suction of the semiconductor chip by the suction means to release the suction state,
2. The ultrasonic flip-chip bonding apparatus according to claim 1, further comprising control means for controlling the bonding tool to move in a direction away from the circuit board held on the table. In an ultrasonic flip chip bonding method in which a semiconductor chip is bonded to a circuit board by applying ultrasonic vibration,
Hold the circuit board on a table movable in at least one axis direction,
The semiconductor chip is adsorbed to a bonding tool that is movably provided so as to move away from the circuit board held on the table,
Move the bonding tool so that it is close to the circuit board, and contact the semiconductor chip adsorbed by the bonding tool to the circuit board.
Apply ultrasonic vibration to the bonding tool,
Detecting the vibration amplitude of the semiconductor chip and the suction pressure at which the semiconductor chip is attracted to the bonding tool,
When the detected amplitude is equal to or less than a predetermined value and the detected suction pressure is equal to or greater than a predetermined value,
Release the adsorption state between the bonding tool and the semiconductor chip,
An ultrasonic flip-chip bonding method, wherein a bonding tool is moved in a direction away from a circuit board .

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