JPH11176883A - Device and method for thermocompression bonding of electronic component having bumps - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermocompression bonding device and a thermocompression bonding method for an electronic component with a bump, which is able to maintain the position correcting accuracy in mounting, even when high-temperature mounting is performed. SOLUTION: In the thermocompression bonding device, wherein an electronic component having a bump is held with a pressure head, the positions of the electronic component and a substrate are recognized by a camera the position of a mounting point is corrected, and the component is subjected to thermocompression bonding to the substrate and to following processes. The position relative to the substrate is fixed. A firs recognition mark M1 is provided in a calibrating stage 8. A second recognition mark M2 of a calibrating jig 9 held by the pressure head 6 is image picked up by cameras 39a and 39b, and the position correction is performed so that these two marks coincide. Thereafter, the calibrating jig 9 is moved on the calibration stage 8 and overlapped. Under this state, the positional deviation between the first recognition mark M1 and the second recognition mark M2 is detected. Thus, the error in the position calibration generated by the deviation of the optical axis of the optical head 38 with the heat at the time of the thermocompression bonding can be calibrated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermocompression bonding apparatus and a thermocompression bonding method for electronic components with bumps for thermocompression bonding electronic components with bumps such as flip chips to a substrate.

[0002]

2. Description of the Related Art With the miniaturization of electronic components and the narrow pitch of wiring patterns, high precision is required for mounting electronic components on a substrate, such as deformation and displacement of the substrate. A method of correcting the position error of the mounting point caused by the image recognition by image recognition is widely used. In this method, before mounting the electronic component, the board or both the board and the electronic component are imaged by a camera, and the position of the board or the electronic component is detected based on the obtained image data. The correction is performed.

In the case where a bump is formed on the lower surface of a semiconductor element such as a flip chip, and the bump is bonded to an electrode of a substrate, the position of the bump needs to be obtained by image recognition in the above-described position correction at the time of mounting. is there.
For this reason, in order to image the bumps of the substrate and the flip chip with the same position reference, it is possible to simultaneously image the bumps of the substrate and the electronic components by positioning the camera between the pressure bonding head holding the flip chip and the substrate. Done. In this camera, an optical head having an optical system mounted on a movable arm is used because it is necessary to retreat from below the pressure bonding head when lowering the pressure bonding head and thermally bonding the flip chip to the substrate.

[0004]

However, in recent years, the temperature at the time of thermocompression bonding has become high, and it has become necessary to heat the substrate itself. For this reason, a heater may be built in the substrate stage that holds the substrate. In such a case, this heat is transmitted to and heated around the base supporting the optical head, and the optical axis of the optical head may be deviated by the deformation due to the heat. The displacement of the optical axis of the optical head naturally has a bad influence on the position accuracy of the image data, and causes a deviation in the position correction accuracy. As described above, in the thermocompression bonding of a flip chip which requires high-temperature mounting, there is a problem that a detection error due to heat occurs in position detection by image recognition, and the position correction accuracy during mounting cannot be ensured.

Accordingly, an object of the present invention is to provide a thermocompression bonding apparatus and a thermocompression bonding method for electronic components with bumps, which can maintain the position correction accuracy at the time of mounting even at high temperature mounting.

[0006]

According to a first aspect of the present invention, there is provided a thermocompression bonding apparatus for electronic components with bumps, comprising: a crimping head for holding electronic components with bumps; elevating means for raising and lowering the crimping head; A positioning portion that positions a substrate holder that holds a substrate to be thermocompression-bonded relative to the pressure bonding head; and an electronic component held by the pressure bonding head and a recognition mark formed on the substrate with the same position reference. An optical head having an image pickup unit for picking up an image, an image recognition unit for recognizing the positions of the substrate and the electronic component based on the image pickup result, and a relative position with respect to the substrate holder fixed and picked up by the image pickup unit A calibration stage provided with a first recognition mark and a calibration jig removably held on the crimping head and provided with a second recognition mark are provided.

According to a second aspect of the present invention, there is provided a thermocompression bonding method for an electronic component with a bump, wherein the electronic component with the bump held by the compression head and the recognition mark formed on the substrate to which the electronic component is thermocompression-bonded are placed at the same position. An electronic component with bumps, which is imaged by an imaging unit having a reference, recognizes the position of the electronic component and the substrate based on the imaged data, determines a position correction amount, and thermocompresses the electronic component to the substrate based on the position correction amount. A method of holding a calibration jig provided with a first recognition mark with the pressure bonding head, and a calibration method provided with a second recognition mark and fixing a relative position with respect to the substrate holder. Positioning a stage below the pressure bonding head; positioning the imaging unit between the pressure bonding head and the calibration stage to image the first recognition mark and the second recognition mark; Calculating a position shift between the first recognition mark and the second recognition mark based on the result, calculating a position correction amount of the calibration stage based on the position shift, and retracting the imaging unit from below the pressure bonding head; Afterwards, a step of correcting the position of the calibration stage based on the position correction amount, lowering the pressure bonding head and mounting the calibration jig on the calibration stage, and positioning the imaging unit on the calibration stage. Imaging the first and second recognition marks superimposed on each other, and storing the amount of misalignment between the first and second recognition marks as a misalignment calibration value based on the imaging result. And a step of calibrating the position correction amount with the calibration value at the time of thermocompression bonding of the electronic component.

According to the present invention, a calibration stage in which a relative position with respect to a substrate is fixed and a first recognition mark is provided, and a second recognition mark of a calibration jig held by a pressure bonding head are attached to a camera. After performing the position correction so that the two recognition marks coincide with each other, the first recognition mark and the second recognition mark are transferred in a state where the calibration jig is transferred and superimposed on the calibration stage. By detecting the displacement of
It is possible to calibrate a position correction error caused by a shift in the optical axis of the optical head due to heat during thermocompression bonding.

[0009]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a side view of a thermocompression bonding apparatus for electronic components with bumps according to an embodiment of the present invention, FIG. 2 is a partial perspective view of the thermocompression bonding apparatus for electronic components with bumps, and FIG. FIG. 4 is a cross-sectional view of a calibration stage of the crimping device, FIG. 4 is a plan view of a position correction calibration mark of the thermocompression bonding device for the electronic component with bumps, and FIG. FIG.

First, the structure of a thermocompression bonding apparatus for electronic components with bumps will be described with reference to FIG. In FIG. 1, XY
A substrate holder 2 is provided on a table 1a which is moved in the horizontal direction by the table 1. The substrate 3 is placed on the substrate holder 2, and the table 1 on the side of the substrate 3 is provided.
The supply unit 4 for the electronic component 5 is disposed on the “a”. XY
By driving the table 1, the substrate 3 and the supply unit 4 move in a horizontal plane. Above the XY table 1, an electronic component 5 is held by a crimping head 6, and the crimping head 6 is mounted on a first lifting block 10.

A slider 11 is fixed to the back surface of the first lifting block 10, and the slider 11 is vertically slidably fitted on a vertical guide rail 12 provided on the front surface of the first frame 13. doing. An inverted L-shaped overhang 14 is provided above the first lifting block 10. The lower surface of the overhang portion 14 is in contact with a load cell serving as load detecting means described later.

Above the first lifting block 10, a second lifting block 20 is provided. A slider 21 is provided on the back surface of the second elevating block 20, and the slider 21 is vertically slidably fitted on a vertical guide rail 22 provided on the front surface of the second frame 23. . An inverted L-shaped overhang 24 is provided below the second lifting block 20. A load cell 26 serving as a strain-type load detecting means is disposed on the upper surface of the overhang portion 24, and the load cell 26 is in contact with the lower surface of the overhang portion 24. A cylinder 25 is mounted on the lower surface of the second lifting block 20 in a downward direction.
Rod 25a is in contact with the upper surface of the overhang portion 24.

A bracket 30 having a U-shaped cross section is fixed to an upper portion of the second frame 23. Bracket 30
A motor 31 is provided on the upper side, and a rotating shaft of the motor 31 is connected to a vertical feed screw 27. Feed screw 2
7 is screwed into a nut 28 built in the second lifting block 20. Therefore, when the motor 31 rotates forward and backward, the nut 28 moves up and down along the feed screw 27, and the second lifting block 20 and the first lifting block 10 move up and down. That is, the motor 31, the feed screw 27 and the nut 2
8 is a crimping head 6 together with the first lifting / lowering block 10
As a lifting means.

The motor 31 is connected to a lift motor drive unit 33, and the lift motor drive unit 33 receives a command from the control unit 43 and controls the rotation of the motor 31. An imaging unit 39 is provided below the first frame 12. The imaging unit 39 includes an optical head 38 that protrudes forward, and moves forward and backward by a feed screw 40 driven by a motor 41. The imaging unit 39 recognizes the positions of the electronic component 5 and the substrate 3 when the optical head 38 advances through the optical head 38 (see 38 indicated by a chain line). An image recognition unit 37 is connected to the imaging unit 39, and the image recognition unit 37 includes a control unit 43.
Is connected to The image data captured by the image capturing unit 39 is sent to the image recognizing unit 37, and is recognized by the image recognizing unit 37. The detected position data of the board 3 and the electronic component 5 is sent to the control unit 43.

The bonding load detector 34 detects a bonding load based on the load value detected by the load cell 26. drive unit 35 drives the angle correcting motor 29 that rotates the pressure bonding head 7 by θ. The motor driving unit 36 drives a motor 41 for moving the optical head 38 and the imaging unit 39 forward and backward. The XY table driving section 42 drives the XY table 1. A storage unit 44 is connected to the control unit 43, and the storage unit 44 includes a program storage area 45 and a data storage area 46. The program storage area 45 stores an operation program of each unit, and the data storage area 46 stores data such as a position correction calibration value.

Next, the structure and arrangement of the optical head 38 will be described with reference to FIG. In FIG. 2, three mirrors 19a, 19b, 19 are provided at the tip of the optical head 38.
c is provided. The central mirror 19c is a double-sided mirror, and light (optical axis b) incident from above is mirror 19c.
And is guided to a camera 39b for electronic component recognition of the imaging unit 39 via a mirror 19b. Similarly, light (optical axis a) incident from below is reflected by the lower surface of the mirror 19c, and is guided to the camera 39a for board recognition of the imaging unit 39 via the mirror 19a.

With the optical head 38 advanced, the mirror 19c is located immediately below the pressure bonding head 6. Therefore, when the XY table 1 is driven to position the calibration stage 8 directly below the crimping head 6, the first recognition mark M1 provided on the calibration stage 8 and the calibration jig 9 held by the crimping head 6 The second recognition mark M2 can be imaged by the board recognition camera 39a and the electronic component recognition camera 39b, respectively. At this time, since the relative positional relationship between the camera 39a and the camera 39b is fixed, the first recognition mark M1 and the second recognition mark M2 are imaged based on the same position reference. Note that, in the above-described example, the first recognition mark M1 is used by another camera 39a, 39b.
Although the second recognition mark M2 and the second recognition mark M2 are imaged, both may be alternately imaged using a single camera. Even in this case, the first and second recognition marks are imaged based on the same position reference.

Next, the calibration stage 8 and the calibration jig 9 will be described with reference to FIG. 3, the calibration stage 8 is a block-shaped member, and is mounted on the XY table 1 at a position where the relative position with respect to the substrate holder 2 is fixed. In the present embodiment, it is attached to substrate holder 2, but may be at any position as long as it moves horizontally with substrate holder 2 (for example, the upper surface of table 1 a).
A concave portion 8a is provided on the upper surface of the calibration stage 8,
A white plate 17 is mounted in the concave portion 8a.
It is fixed in a. On the upper surface of the plate 17, a circular first recognition mark M1 is provided.

A calibration jig 9 is mounted on the calibration stage 8, and the suction jig 9 is evacuated to a vacuum by suctioning the suction hole 18b.
Is fixed on the upper surface of the calibration stage 8. The calibration jig 9 is formed of a transparent plate, and an annular second recognition mark M2 is provided on a lower surface of the calibration jig 9. As will be described later, the calibration jig 9 is used by being held by the suction head 6 or mounted on the calibration stage 8 only when performing a calibration process for position correction. With the calibration jig 9 placed on the calibration stage 8, the calibration stage 8 is positioned immediately below the pressure bonding head 6, the optical head 38 is moved forward, and a camera 39 a captures an image of the lower side. As shown in the image 50, an image in which the first recognition mark M1 and the second recognition mark M2 are overlapped in the same image can be obtained.

This thermocompression bonding apparatus for electronic components with bumps is configured as described above, and the operation will be described below. First, in FIG. 1, the XY table 1 is driven to drive the lifting / lowering motor 31 with the supply unit 4 positioned below the pressure bonding head 6, thereby lowering the pressure bonding head 6 and picking up the electronic component 5. Once held, the pressure bonding head 6 is raised. Next, with the substrate 3 positioned below the pressure bonding head 6, the motor 41 is driven to advance the optical head 38, and images of the substrate 3 and the electronic component 5 are taken by the cameras 39a and 39b. The positions of the board 3 and the electronic component 5 are recognized by the image recognition unit 37 based on the image data. The control unit 43 drives the XY table 1 based on the recognition result,
The position of the mounting point is corrected, and the electronic component 5 is thermocompression-bonded to the substrate 3.

During the thermocompression bonding, the substrate holder 2 is heated to a high temperature by a heater, and this heat is transmitted to the surroundings. The base of the drive unit that moves the optical head 38 back and forth is also deformed by this heat. As a result, the optical axes a and b shown in FIG.
Of the camera 39a, 39
A displacement occurs in the recognition result of b. Therefore, an error occurs in the position correction of the mounting point, and correct mounting cannot be performed. Therefore, the calibration process performed to calibrate the error of the position correction due to the heat will be described with reference to the flow of FIG.

First, the XY table 1 is driven to position the calibration stage 8 below the pressure bonding head 6 (ST1). Next, the calibration jig 9 placed on the calibration stage 8 is sucked and held by the pressure bonding head 6 (ST2). In this state, the optical head 38 is advanced between the thermocompression head 7 and the calibration stage 8. (ST3). Next, the cameras 39a and 39b
Thereby, the first recognition mark M1 of the calibration stage 8 and the second recognition mark M2 of the calibration jig 9 are imaged (ST4).

As a result, as shown in FIGS. 4A and 4B, images of the first recognition mark M1 and the second recognition mark M2 are obtained. Next, the displacement (dx1, dy1) of the first recognition mark M1 and the displacement (dx2, dy2) of the second recognition mark M2 are obtained from the obtained image (ST).
5). Thereby, the position correction distance Δx = dx1−dx2, Δy = dy1−dy2 of the calibration stage 8 for matching the first recognition mark M1 and the second recognition mark M2 is calculated (ST6).

Next, the optical head 38 is retracted from below the pressure bonding head 6 (ST7), and the calibration stage 8 is moved by the position correction distances Δx and Δy to obtain the first recognition mark M1.
And the second recognition mark M2 are aligned (ST
8). Next, the crimping head 6 is lowered, the calibration jig 9 is mounted on the calibration stage 8 (ST9), and the crimping head 6 is raised (ST10). Thereafter, the optical head 38 is advanced again onto the calibration stage 8 (ST11), and the camera 39a
The first recognition mark M1 and the second recognition mark M2, which are superimposed on each other, are imaged.

Here, if the optical axes a and b of the optical head 38 are in a correct positional relationship, the positional deviation between the first recognition mark M1 and the second recognition mark M2 is determined by the position correction distances Δx and Δy obtained in ST6. Has been corrected and the first recognition mark M
The center positions of the first and second recognition marks M2 should match, but as described above, the optical axes a and b are deviated due to a temporal change during the thermocompression operation. Since the error of the position correction caused by the deviation of the optical axis appears as a position shift between the first recognition mark M1 and the second recognition mark M2, FIG.
As shown in (c), the first image is obtained from the image obtained in ST12.
Misalignment d between the recognition mark M1 and the second recognition mark M2
If X and dY are obtained (ST13), this positional deviation dX,
dY is a calibration value for calibrating the position correction error. The calibration value thus obtained is stored in the data storage area 46 of the storage unit 44.

This calibration process is performed at appropriate intervals during the thermocompression bonding operation, and each time the calibration value is updated based on the displacement at that time. By correcting the mounting position at the time of thermocompression bonding based on the calibration value of the position correction error obtained in this way, it is possible to always perform correct position correction and perform high-precision mounting. In this case, by providing a calibration stage dedicated to calibration, it is not necessary to use a dummy work for calibration.Therefore, each time calibration is performed, the thermocompression bonding operation is interrupted to save the labor and time for manually setting the dummy work. Can be.

In this embodiment, the X direction and the Y direction
The case where the position correction in the direction is performed has been described. However, by providing crosshairs in the first recognition mark M1 and the second recognition mark M2, the position deviation in the θ direction can be detected, and based on the detection result, If the θ motor 29 is driven in this way, it is possible to calibrate the rotational position correction amount in the θ direction when mounting electronic components. Further, in the present embodiment, the calibration jig 9 is constituted by a transparent plate. However, the present invention is not limited to this. When the calibration jig 9 is placed on the calibration stage 8, the first recognition mark M1 thereunder is provided. Can be observed from above.

[0028]

According to the present invention, there is provided a calibration stage having a fixed position relative to a substrate and provided with a first recognition mark,
After imaging the second recognition mark of the calibration jig held by the crimping head with a camera and performing position correction so that the two recognition marks coincide with each other, the calibration jig is transferred onto the calibration stage. The position error between the first recognition mark and the second recognition mark is detected in a state where they are superimposed on each other, so that the heat of the thermocompression bonding causes the optical axis of the optical head for position recognition of the substrate and the electronic component to be moved. A calibration value required to calibrate the position correction error caused by the deviation can be obtained with high accuracy. Therefore, thermocompression bonding of electronic components requiring high-temperature mounting can be performed with high positional accuracy, and a special calibration stage is provided. In addition, it is possible to perform high-efficiency thermocompression bonding without the labor and time of setting the dummy work manually.

[Brief description of the drawings]

FIG. 1 is a side view of a thermocompression bonding apparatus for electronic components with bumps according to an embodiment of the present invention.

FIG. 2 is a partial perspective view of a thermocompression bonding apparatus for electronic components with bumps according to an embodiment of the present invention.

FIG. 3 is a sectional view of a calibration stage of the thermocompression bonding apparatus for electronic components with bumps according to one embodiment of the present invention.

FIG. 4 is a plan view of a position correction calibration mark of the thermocompression bonding apparatus for electronic components with bumps according to one embodiment of the present invention.

FIG. 5 is a flowchart of a position correction calibration process of a thermocompression bonding apparatus for electronic components with bumps according to an embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 XY table 3 Substrate 5 Electronic component 6 Crimping head 8 Calibration stage 9 Calibration jig 10 First elevating block 20 Second elevating block 31 Motor 37 Image recognition unit 38 Optical head 39 Image pickup unit 43 Control unit 44 Storage unit

Continued on the front page (51) Int.Cl. ⁶ Identification code FI H05K 3/32 H05K 3/32 C

Claims (2)

[Claims] 1. A crimping head for holding an electronic component with bumps, elevating means for raising and lowering the crimping head, and a substrate holder for holding a substrate on which the electronic component is thermocompression-bonded with respect to the crimping head. A positioning part for positioning the
An optical head having an image pickup unit for picking up an electronic component held by the pressure bonding head and a recognition mark formed on the substrate with the same position reference; and a position of the substrate and the electronic component based on the imaged result. A calibration stage provided with a first recognition mark fixed at a relative position with respect to the substrate holder and imaged by the imaging unit, and a second recognition unit detachably held by the crimping head. A thermocompression bonding apparatus for electronic components with bumps, comprising: a calibration jig provided with a mark. 2. An electronic part having bumps held by a pressure bonding head and a recognition mark formed on a substrate to which the electronic part is thermocompression-bonded are imaged by an image pickup unit having the same position reference, and based on image data. A method for thermocompression bonding of an electronic component with bumps, wherein a position correction amount is obtained by recognizing the position of the electronic component and the substrate, and the electronic component is thermocompression-bonded to the substrate based on the position correction amount. Holding the calibration jig provided with the crimping head, and positioning a calibration stage provided with a second recognition mark and having a fixed relative position with respect to the substrate holder below the crimping head, A step of positioning the imaging section between the pressure bonding head and the calibration stage to capture an image of the first recognition mark and the second recognition mark; Recognition Calculating a position correction amount of the calibration stage from the positional deviation determined the positional deviation of the click, the imaging unit after being retracted from below the bonding head,
A step of mounting the calibration jig on the calibration stage by lowering the pressure bonding head by correcting the position of the calibration stage based on the position correction amount, and positioning the imaging unit on the calibration stage, Imaging the first recognition mark and the second recognition mark which are superimposed, and registering the amount of misalignment between the first recognition mark and the second recognition mark in the storage unit as a misalignment calibration value based on the imaged result And a step of calibrating the position correction amount with the calibration value at the time of thermocompression bonding of the electronic component.