JPH08306740A - Bonding head - Google Patents

Abstract

PURPOSE: To enhance the bonding quality by automating the parallelization of a heater chip in a bonding head for bonding the lead of an IC to a printed board. CONSTITUTION: A heater chip 1 is secured to the forward end part of an insulation block 2 such that it can be swung freely by means of a piezoelectric actuator 5 about a fulcrum, i.e., a pin 11, with respect to a block 3. The block is moved up and down with respect to a work by means of an elevator, i.e., a cylinder 4, thus producing a pressing force required for the bonding. A reference block 10 for mounting the work to be bonded is disposed under the heater chip 1 with two displacement sensors 7, 7 being aligned with the opposite end positions of the heater chip 1 in the longitudinal direction. The displacement sensor 7, 7 detects the inclination of heater chip pressing surface and the piezoelectric actuator 5 is driven by a drive section 9 based on the detection results.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a bonding head in a bonding apparatus for bonding C onto a printed circuit board with high precision, and particularly to a tape automated bonding (hereinafter referred to as TAB).
The present invention relates to a bonding head which is used for collectively bonding an IC having a narrow lead pitch and a large number of pins on a printed circuit board, such as an IC according to a conventional method.

[0002]

2. Description of the Related Art In a bonding apparatus used as a semiconductor manufacturing apparatus, a lead of an IC, which is a semiconductor device to be bonded, and an electrode portion formed on a printed circuit board are heated in a state where a pressing force is applied thereto, and thermocompression bonding is performed. The structure shown in FIGS. 4A and 4B has been conventionally known as a bonding head for bonding by the method described above.

To explain this, reference numeral 1 in the drawing is a heater chip which is connected to a welding power source (not shown) and is heated to a predetermined temperature, 2 is an insulating block having the heater chip 1 attached to its tip portion, and 4 is this insulation. It is a cylinder as an elevating device for moving the block 2 up and down. On the other hand, code 10
Reference numeral denotes a reference block which receives a work to be bonded (indicated by reference numeral 12 in FIG. 5) below the heater chip 1 on its upper surface. The units as the bonding head shown in FIG. 4 are used by, for example, arranging four sets corresponding to the leads formed on the four sides of the IC.

The bonding work using the bonding head having the above-described structure is performed as follows. That is, as shown in FIG. 5, the printed circuit board 1 as the bonded work 12 is provided on the upper surface of the reference block 10.
3 and the leads 14 of the IC are positioned and placed. Then, the heater chip 1 is lowered by the cylinder 4 from above, the IC leads 14 are pressed against the respective electrode portions on the printed circuit board 13 with a predetermined pressing force, and in this state, they are thermocompression bonded. If the heater chip 1 is raised by the cylinder 4 after a predetermined time has elapsed, the bonding operation is completed.

[0005]

According to the conventional bonding head as described above, when the heater chip 1 is not parallel to the printed circuit board 13 on the reference block 10 or the work 12 to be bonded on the reference block 10. As shown in FIG. 5, the heater chip 1 hits one side and the bonding process cannot be performed in a desired state.

Further, if the bonding is performed in the state where the above-mentioned one-sided contact occurs, the IC lead 14 is displaced and bonded to each electrode portion of the printed circuit board 13, the lead itself is bent, and the IC is further broken. The bonding state between the leads 14 and the printed circuit board 13 becomes non-uniform, and highly accurate bonding cannot be performed, which is a problem in terms of bonding quality. In particular, recently, there has been a tendency to increase the number of pins and miniaturization, and the lead pitch of the IC has become narrow. Even if the lead is slightly displaced or bent, a short-circuit between unconnected portions and leads during the bonding process. May occur.

In order to solve such a problem, usually, immediately before the bonding operation, the pressing surface of the heater chip 1 is brought into direct contact with the upper surface of the reference block 10 to apply a pressing force. By obliquely adjusting the inclination of the heater chip 1 with respect to the reference block 10 while observing the indentation, the heater chip 1 is parallelized. However, such parallel alignment of the heater chip 1 often requires parallel alignment with high accuracy of, for example, 10 μm or less, and there is a drawback in that the adjustment requires a great number of man-hours and troubles.

When the work 12 to be bonded is changed or the bonding area in the work 12 to be bonded is changed, the heater chip 1 or the reference block 10
It is necessary to replace a tool such as (a tool constituting the bonding head). However, in such a case, it is necessary to carry out the adjustment work such as parallelizing the heater chip 1 described above each time, which requires a lot of man-hours and labor for the adjustment, and the tool replacement is complicated. .

The present invention has been made in view of the above circumstances, and a heater chip provided at the tip of the head when bonding the IC lead as the work to be bonded and the electrode portion of the printed circuit board by collective bonding or the like. It is an object of the present invention to obtain a bonding head capable of improving the bonding quality by automating the parallel alignment of.

[0010]

In order to meet such a demand, a bonding head according to the present invention is provided with a bonding head which moves up and down by a lifting device above a reference block for mounting a workpiece to be bonded. A block that is provided and moves up and down, and an insulating block that rotatably pivots a portion of one side closer to the lower side and that is swingably held by interposing a piezoelectric actuator in a portion closer to the other side, It is composed of a heater chip which is provided at the tip of the heater chip and is heated by energization, and two displacement sensors are provided on the reference block in accordance with both end positions of the heater chip in the longitudinal direction. It is provided with a control device for controlling the energization of the piezoelectric actuator from the contact state of the heater chip with the upper surface of the reference block.

In the bonding head according to the present invention, the block on the elevating device side and the insulating block on the lower side of which is rotatably rotatably supported and swingably held are both blocks. A piezoelectric actuator interposed in a portion closer to the other side is moved toward and away from each other by expansion and contraction in the vertical direction, and a tension spring is spanned on the opposite side of the shaft supporting portion of both blocks.

Further, in the bonding head according to the present invention, the control device for controlling the energization of the piezoelectric actuator for controlling the swinging operation of the insulating block having the heater chip is detected by the two displacement sensors provided on the reference block. An operational amplifier that outputs a displacement signal by taking the difference between the outputs of the respective displacement sensors based on the contact state at both ends of the heater chip, and a piezoelectric actuator that generates a displacement amount proportional to the output signal from the operational amplifier. And a drive unit that outputs the voltage of

[0013]

According to the present invention, the work to be bonded is placed on the upper surface of the reference block, and the elevating device is driven to lower the insulating block and the block provided with the heater chip at the tip. Then, when the heater chip comes into contact with the workpiece to be bonded on the reference block, the piezoelectric actuator is driven in accordance with the signal obtained by the displacement sensor, whereby the insulating block swings with respect to the block on the lifting / lowering device side, and moves in parallel. Can be performed in a state where the feeding is automatically corrected. By heating the heater chip in this state, the work to be bonded can be bonded.

[0014]

1 (a), 1 (b) and 2 show an embodiment of a bonding head according to the present invention. In these figures, the same or corresponding parts as those shown in FIGS. Are denoted by the same reference numerals, and detailed description is omitted.

The heater chip 1 for thermocompression bonding the printed circuit board 13 as the work 12 to be bonded and the IC lead 14 is connected to a welding power source (not shown), and the pressing surface in contact with the work 12 has a uniform temperature distribution. Controlled to the heating state.

The heater chip 1 is fixed to the tip side of the insulating block 2, and the insulating block 2 is further provided with a pin 1.
Block 3 attached to the tip of cylinder 4 by 1.
Is supported in a state in which a portion closer to one side is rotatably supported at the front end side. It is desired that the pin 11 is formed so that the rattling of the shaft support portions of both blocks 2 and 3 is as small as possible.

A piezoelectric actuator 5 is interposed between a portion of the block 3 on the other side and one side of the insulating block 2 facing the portion, and the piezoelectric actuator 5 expands and contracts when energized. The insulating block 2 is configured to swing with respect to the block 3 with the pin 11 serving as a shaft supporting portion serving as a swing supporting point. Note that the piezoelectric actuator 5 may be disposed so as to straddle a slightly larger recess formed in both the blocks 2 and 3. Further, in this embodiment, the case where both ends of the piezoelectric actuator 5 are formed in a hemispherical shape so as to abut substantially in a point contact state with the end face of each recess is illustrated.

Here, on the side of the block 3 and the insulating block 2 on the side opposite to the shaft supporting portion by the pin 11, in order to eliminate the mutual gap between the block 3 and the insulating block 2 with the piezoelectric actuator 5 interposed. And one end to block 3
A tension coil spring 6 is stretched over the side portion of the insulating block 2 by hooking the other end on the side portion of the insulating block 2. The tension coil spring 6 may have a weak biasing force. The point is that the side portions of the blocks 2 and 3 on the opposite side of the pin 11 can be connected so as to be relatively close to and away from each other. The block 3 provided at the tip of the cylinder 4, which is the lifting device, moves up and down by the cylinder 4, whereby the heater chip 1 provided at the tip of the insulating block 2 is provided.
The pressing force of the cylinder 4 is controlled so that a predetermined pressing force is generated on the pressing surface of the cylinder 4.

On the other hand, below the heater chip 1, a printed circuit board 13 which is a work 12 to be bonded is provided on the upper surface thereof.
And a reference block 10 on which the IC leads 14 are placed. The reference block 10 is provided with two displacement sensors 7, 7 according to the positions of both ends of the heater chip 1. The outputs of these two displacement sensors 7, 7 are differentiated by a differential amplifier 8, and a displacement signal is output to a drive unit 9. The driving section 9 is configured to output a voltage for causing the piezoelectric actuator 5 to generate a displacement amount proportional to the displacement signal.

According to the bonding head having such a configuration, when the reference block 10 on which the workpiece 12 to be bonded is mounted is inclined as shown in FIG. It can be adjusted and corrected automatically.

That is, the output voltage of the drive section 9 is set so that the length of the piezoelectric actuator 5 becomes the shortest in the state where there is no work 12 to be bonded. Also, the cylinder 4 lowers the heater chip 1 until it contacts the upper surface of the reference block 10. At this time, the pressure of the cylinder 4 is set to a low pressure so that the reference block 10 is not damaged and the heater chip 1 is not deformed. Then, the displacement sensors 7 and 7 detect the heights of both ends of the heater chip 1, and the differential amplifier 8 outputs the difference between the heights detected by the two displacement sensors 7 and 7 as a displacement signal. The piezoelectric actuator 5 is driven.

This operation is continued until the pressing surface of the heater chip 1 becomes parallel to the reference block 10 and the outputs of the two displacement sensors 7, 7 match. When the above-described operation is completed, the output voltage of the drive unit 9 is fixed, and the length of the piezoelectric actuator 5 is determined. Thereafter, the heater chip 1 is raised by the cylinder 4. As a result, the parallelization of the heater chip 1 is automatically performed and corrected.

Next, in the above-mentioned state, as shown in FIG. 2, the substrate 13 and the IC lead 14 as the work 12 to be bonded are mounted on the upper surface of the reference block 10 in an overlapping manner. When the heater chip 1 is lowered by the cylinder 4 in this state, the pressing surface of the heater chip 1 is lowered in parallel with the IC lead 14 and the substrate 13, and a uniform pressure is applied to each lead 14 of the IC. Will be added. By connecting the heater chip 1 to a welding power supply and heating it in this pressurized state, bonding such as a batch bonding process can be performed with stable quality.

For example, a heater that uses a spherical bearing or the like to make the above-mentioned heater chip 1 parallel to the reference block 10 has been known. However, when such a structure is adopted, it is necessary to always supply a lubricant to the bearing portion. On the other hand, in the bonding head according to the present invention, since paralleling can be performed only by driving the piezoelectric actuator 5, such a lubricant is not required, and maintenance and the like can be easily performed.

In the bonding head having the above-described structure, the insulating block 2 and the block 3 are
There is a possibility that the shaft 1 may float by the amount of play at the shaft support.
However, the setting of the output voltage from the drive unit 9 to the piezoelectric actuator 5 interposed between the blocks 2 and 3 is performed in a state where the blocks 2 and 3 are pressed against the reference block 10 by the cylinder 4, and the bonding is performed. This is the same state as when both blocks 2 and 3 are lowered and pressed onto the workpiece 12 to be bonded by the cylinder 4 in order to perform the above operation. Therefore, when performing the bonding process, there is no problem in the backlash at the pivot portion by the pin 11 described above.

Pin 1 between both blocks 2 and 3 as described above
In order to prevent play due to backlash at the shaft support by 1
For example, it is conceivable to adopt the structure shown in FIGS. That is, in both blocks 2 and 3, it is preferable to stretch the tension coil spring 20 between the side portions of the pins 11 on the side of the shaft support portion. This way, pin 1
Although the backlash at the shaft support by 1 is always constant regardless of the vertical movement by the cylinder 4, both blocks 2, 3
No unnecessary movement between them occurs. Such a tension coil spring 20 only needs to have the same urging force as the tension coil spring 6 that connects the opposite sides of the blocks 2 and 3. Of course, as the piezoelectric actuator 5, one that can generate a force sufficiently larger than these springs 6 and 20 is used.

The present invention is not limited to the structure of the above-described embodiment, but the shape of each part constituting the bonding head,
The structure and the like may be modified or changed as appropriate, and as a tool to be bonded to which the structure is applied, any conventionally known bonding object by thermocompression bonding can be applied.

Further, in the above-described embodiment, the bonding processing of the lead on one side of the IC using the bonding head has been described.
The effect can also be obtained by utilizing C when performing a bonding process. That is, by installing the bonding head shown in the above-described embodiment in correspondence with the leads on the four sides of the IC to be bonded, the leads 1 on these four sides
4 can be bonded to the substrate 13.

[0029]

As described above, according to the bonding head of the present invention, the bonding head that moves up and down by the elevating device above the reference block is a block that moves up and down by the elevating device, and one side below the block. An insulating block that rotatably supports a portion near to the other side and is swingably held with a piezoelectric actuator interposed at a portion near the other side, and a heater provided at the tip of the insulating block and heated by energization. And a displacement sensor provided on the reference block at both ends of the heater chip in the longitudinal direction, and a piezoelectric actuator based on the contact state of the heater chip detected by these displacement sensors with the upper surface of the reference block. Since a control device for controlling energization to the device is provided, it will be described below in spite of its simple structure. Achieve the effect.

That is, according to the present invention, the inclination of the pressing surface of the heater chip at the tip of the insulating block provided on the block on the lifting device side so as to be swingable is detected by the displacement sensor,
The displacement output drives the piezoelectric actuator to oscillate the insulating block and automatically aligns the heater chip, so parallelizing the heater chip, which previously required a lot of man-hours, can be simplified. Moreover, it can be performed in a short time.

Further, according to the present invention, it is possible to eliminate the variation that has occurred when the parallel alignment of the heater chip pressing the work to be bonded is conventionally performed by manual adjustment, and the bonding quality can be reduced. And high-precision bonding can be stably performed. In particular, according to the bonding head according to the present invention, the heater chip for pressing and thermocompression bonding against the work to be mounted placed on the upper surface of the reference block can be automatically corrected and parallelized. In addition, the effect can be exhibited in performing the batch bonding process.

[Brief description of drawings]

1A and 1B show an embodiment of a bonding head according to the present invention, in which FIG. 1A is a block diagram thereof, and FIG. 1B is a side view of an essential part thereof.

FIG. 2 is a diagram showing a bonding state using the bonding head in the embodiment of FIG.

3A and 3B show another embodiment of the bonding head according to the present invention, wherein FIG. 3A is a block diagram thereof, and FIG. 3B is a side view of a main part thereof.

FIG. 4A is a block diagram showing a conventional bonding head, and FIG. 4B is a side view of a main part thereof.

FIG. 5 is a diagram showing a state of bonding using the bonding head shown in FIG. 4;

[Explanation of symbols]

1 ... Heater chip, 2 ... Insulation block, 3 ... Block,
4 ... Cylinder (elevating device), 5 ... Piezoelectric actuator,
6 ... tension coil spring (tensile spring), 7 ... displacement sensor, 8 ... differential amplifier, 9 ... drive unit (control device), 10 ...
Reference block, 11: pin, 12: work to be bonded, 13: printed circuit board, 14: IC lead, 20: tension coil spring.

Claims (3)

[Claims] 1. A bonding head which is moved up and down by an elevating device above a reference block on which a work to be bonded is mounted on an upper surface, the bonding head being provided in the elevating device and being moved up and down; An insulating block that rotatably supports a portion closer to one side on the lower side and that is swingably held by interposing a piezoelectric actuator in a portion closer to the other side, and is provided at a distal end portion of the insulating block. And a heater chip heated to a predetermined temperature by energization,
Two displacement sensors are provided on the reference block so as to be aligned with both ends of the heater chip in the longitudinal direction, and the piezoelectric actuator is moved from the contact state of the heater chip detected by the two displacement sensors to the upper surface of the reference block. A bonding head provided with a control device for controlling energization of the bonding head. 2. The bonding head according to claim 1, wherein the block on the side of the elevating device and the insulating block which is pivotally supported by a portion near one side below the block so as to be swingable include: These blocks are configured so that they can be approached or separated by vertical expansion and contraction of a piezoelectric actuator interposed in a portion closer to the other side, and a tension spring is stretched over the opposite sides of the shaft support portions of both blocks. A bonding head characterized in that: 3. The bonding head according to claim 1, wherein a control device for controlling energization of a piezoelectric actuator for controlling a swinging operation of an insulating block provided with a heater chip at a tip portion is provided on the reference block. An operational amplifier that outputs a displacement signal by taking the difference between the outputs of the respective displacement sensors based on the contact state at both ends in the longitudinal direction of the heater chip detected by the two displacement sensors provided at the output amplifier, and an output from the operational amplifier. A driving unit that outputs a voltage for causing the piezoelectric actuator to generate a displacement amount proportional to a signal.