JP3475776B2 - Flip chip bonding apparatus and flip chip bonding method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate (specifically, a semiconductor device which is placed with the electrode surface facing the substrate and electrically connected to the substrate through a conductive bump). , A flip chip bonding apparatus and a flip chip bonding method for bonding to a printed circuit board or an IC package, for example.

[0002]

2. Description of the Related Art A flip chip bonding apparatus for joining a flip chip and a wiring board is generally equipped with a height adjusting mechanism, a pressure adjusting mechanism, or both, and the control method thereof is as follows. Are known.

A conventional flip chip bonding apparatus will be described below. For example, JP-A-8-13023
In Japanese Patent Laid-Open No. 1-81, a heat tool for adsorbing and heating a flip chip is first lowered by an AC servomotor until the flip chip comes into contact with a bump on a wiring board. Next, when the load cell detects contact between the flip chip and the wiring board, the heat tool is stopped and this position is set as the reference position. Next, when heating is started and the temperature of the heat tool reaches the set temperature, it is lowered from the heat tool reference position by the set amount, adsorption is stopped and released, and then the heat tool is raised. Is listed.

Further, for example, in the semiconductor mounting device disclosed in Japanese Patent Application Laid-Open No. 8-204391, a tool for holding a semiconductor element or the like is adjusted in position in the height direction with respect to the wiring board, and the wiring board is mounted via the semiconductor element. A linear motor for adjusting the load is provided. The operation of this device is as follows. First, the tool is lowered by the positioning operation to ground the semiconductor element to the wiring board, and contact detection of whether or not it is grounded is performed by using the increase in the torque (current) command value of the linear motor. Detect and enter the pressurized state. Pressurization is performed by applying a current proportional to the pressurization value to the linear motor for a certain period of time. When the pressurization is completed, the positioning operation is started and the tool is raised and positioned at the origin position.

[0005]

However, in these conventional flip chip bonding apparatuses, since the descent of the tool holding the flip chip is electrically controlled, the conductive bump of the flip chip and the wiring board are not controlled. When contacting, heating and adhering, it is difficult to control the height of the flip chip while pressing the flip chip against the wiring substrate with a predetermined bonding load.
Adjacent bumps may be crushed too much due to overshoot to short-circuit the circuit, or the load may be insufficient to deteriorate the adhesiveness of the solder.

The present invention has been made in view of the above points, and an object of the present invention is to realize flip chip bonding capable of reliable electrical connection. In addition, it is an object of the present invention to eliminate the problem that the bumps are crushed too much due to overshoot and short-circuited with the adjacent bumps, and stable flip chip bonding is performed. Another object is to enable flip chip bonding with a simple mechanism.

[0007]

A flip chip bonding apparatus according to the present invention is a flip chip bonding apparatus for electrically connecting a flip chip to a substrate via a conductive bump formed on the flip chip. Chip suction means for sucking a flip chip,
Stopping means for mechanically stopping the chip suction means, and driving means for driving the chip suction means in a direction perpendicular to the surface of the substrate, the chip suction means being movably attached, and the stopping means being fixed. A bonding head, a measuring means for measuring a relative distance between a predetermined portion of the bonding head and a predetermined portion of the chip suction means,
The storage means for storing the set value of the relative distance is compared with the measured value of the relative distance and the set value of the relative distance, and the bonding head is stopped at a position where the measured value and the set value are equal. A control means for controlling the drive of the bonding head by the drive means, and a pressing means for pressing and moving the chip suction means to a stop position by the stop means after the bonding head is stopped by the control means. It is characterized by having and.

Further, the measuring means measures the relative distance between the predetermined portion of the bonding head and the substrate surface, instead of measuring the relative distance between the predetermined portion of the bonding head and the predetermined portion of the chip suction means. It is what

The pressurizing means is an air cylinder.

Further, the present invention is characterized in that a heating means for heating the bump to melt or deform it while the load is applied to the bump by the pressing means is provided.

A flip chip bonding method according to the present invention is a flip chip bonding method in which a flip chip is electrically connected to a substrate through a conductive bump formed on the flip chip, and is movably attached to a bonding head. The flip chip is attracted to the chip suction means, and the bonding head is moved in a direction perpendicular to the surface of the substrate, and the relative distance between the predetermined portion of the bonding head and the predetermined portion of the chip suction means is set. The bonding head is stopped at a position equal to the value, and after the bonding head is stopped, the chip suction means is pressed to move in the direction perpendicular to the substrate surface in the substrate direction, and the stopping means fixed to the bonding head is used. At the stop position, mechanically stop the chip suction means. It is characterized in that to.

Further, instead of stopping the bonding head at the position where the relative distance between the predetermined portion of the bonding head and the predetermined portion of the chip suction means becomes equal to the set value as described above, the predetermined portion of the bonding head and the substrate surface are It is characterized in that the bonding head is stopped at a position where the relative distance is equal to the set value.

Further, the present invention is characterized in that the bumps are heated to melt or deform while the load is applied to the bumps.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1. An embodiment of the present invention will be described below with reference to FIGS. 1 to 5. FIG. 1 is a cross-sectional view of essential parts showing a flip-chip bonding apparatus according to the present invention, and illustration of storage means and control means, which are constituent elements of this apparatus, is omitted. Further, FIG. 2 is a conceptual diagram showing the mutual relation of each constituent element including the storage means and the control means described below, such as a measuring means, a pressurizing means, a heating means and a driving means.

In FIG. 1, 1 is a flip chip, and 2 is a wiring board mounted on a bonding stage 3 to which the flip chip 1 is electrically connected via conductive bumps 4.

Numeral 12 is a drive means controlled by a control signal A from a control means not shown in FIG.
Reference numeral 1 is a bonding head that is driven in the X, Y, and Z directions by the driving means 12, and 7 is attached to the bonding head 11 via a linear guide 13 so as to be vertically movable, and the flip chip 1 is sucked from a suction port 9. It is a chip suction means capable of vacuum suction by suctioning air.

Further, 14 is a mechanical stopper fixed to the bonding head 11 and mechanically restricting the lowering of the chip suction means 7, and 15 is the bonding head 11.
Between a predetermined portion of the chip suction means 7 and a predetermined portion of the chip suction means 7 (specifically, in the present embodiment, a portion having the same height as the upper end portion of the mechanical stopper 14 of the bonding head 11 and the chip suction portion 7). Is a relative distance from the contact portion with the mechanical stopper) and sends the measured value φ to the control means (not shown). Here, the chip suction means 7 is pressed against the mechanical stopper 14 by its own weight or a spring (not shown) with a weak force.

Referring now to FIG. As mentioned above,
The displacement meter 15 sends the measured value φ to the control means 5. Further, in this figure, it is a storage means for storing the desired set value ψ of the gap, and the control means 5 compares the measured value φ of the gap with the set value ψ of the gap, and the measured value φ of this gap is compared. And the gap setting value ψ are equal, the control signal A is sent to the driving means 12 so that the bonding head 11 stops at a position where the bonding head 11 is stopped.
The vertical movement of is controlled.

Further, in FIG. 2, reference numeral 16 is a position where a predetermined load is applied to the bump 4 via the chip suction means 7 after the above-mentioned bonding head 11 is stopped, and the chip suction means 7 is stopped by the mechanical stopper 14. It is an air cylinder that is a pressurizing means that can be pushed down.
Here, the load control by the air cylinder 16 is realized by sending a control signal B from the control means 5 to the precision pressure adjusting valve 10 to perform pressure adjustment. Further, when the load is not applied, the movable shaft of the air cylinder 16 is prevented from coming into contact with the tip suction means 7.

Further, in FIGS. 1 and 2, reference numeral 8 is a heater tool which is a heating means for receiving the control signal C from the control means 5 and heating the bumps 4 in a state where a load is applied by the air cylinder 16. Here, this heater tool 8
Is fixed to the chip suction means 7 and has a heater built therein.

Next, the operation of the flip chip bonding apparatus will be described. First, the bonding head 11 is moved down by using the driving means 12 according to the control signal A from the control means 5 while the flip-chip 1 is sucked by the chip suction means 7. Then, the conductive bumps 4 of the flip chip and the conductive bumps of the wiring board 2 come into contact with each other. Then, when the bonding head 11 is further lowered, only the bonding head 11 moves while the chip suction means 7 remains stationary, so that a gap φ is generated between the mechanical stopper 14 and the chip suction means 7. When the gap φ detected by the displacement gauge 15 becomes equal to the set value ψ stored in the storage means 6, the bonding head 11 is driven by the drive means 12 which responds to the control signal A from the control means 5. Stop.

Then, the chip suction means 7 is used by using the air cylinder whose bonding load is precisely adjusted by the precision pressure control valve 10 capable of precisely controlling the air pressure in accordance with the control signal B from the control means 5. A bonding load is applied to the bumps 4 via. As a result, the bump 4 on the flip chip and the bump on the wiring board 2 are pressed against each other.

Next, the bumps 4 are heated by using the heater tool 8 according to the control signal C from the control means 5. As a result, the bump 4 is melted or deformed, and the chip suction means 7 moves by the gap ψ. Then, it stops at a position corresponding to the mechanical stopper 14 (stop position), and the flip chip 1 is held at the set height (stop position). Then, after a lapse of a predetermined time, the heating is stopped and at the same time the chip adsorption is stopped and released, and the heater tool 8 is raised.

The above operation will be described with reference to FIGS. 3 to 5 are cross-sectional views of main parts showing the operation of the flip chip bonding apparatus in order. First, as shown in FIG. 3, the wiring board 2 placed on the bonding stage 3
The bonding head 11 holding the flip chip 1 by vacuum suction is lowered above the
The bumps 4 and the wiring board 2 are brought into contact with each other. At this time, since the chip suction means 7 is pressed against the mechanical stopper 14 of the bonding head 11 by a spring (not shown) or its own weight with a weak force, it can be brought into contact with a small impact load.

Further, when the bonding head 11 is lowered, the chip suction means 7 remains stationary.
As shown in FIG. 4, a gap φ is generated between the mechanical stopper 14 and the chip suction means 7, and this is detected by the displacement gauge 15. The bondin head 11 is stopped at a position where the detected gap φ is equal to the set value ψ.

In this state, as shown in FIG. 5, air whose pressure has been precisely adjusted by the precision pressure adjusting valve 10 to correspond to the set load is supplied, and the air cylinder 16 passes through the tip suction means 7. A bonding load is applied to the bumps 4 on the flip chip 1 to press the bumps 4 on the flip chip 1 and the bumps on the wiring board 2. Next, the bumps 4 are heated by using the heater tool 8 at. As a result, bump 4
Is melted or deformed, and the chip suction means 7 moves by the gap setting value ψ. Then, the mechanical stopper 14
Stop at the position corresponding to.

Next, when a predetermined time has elapsed, the heating of the heater tool 8 is stopped and at the same time the adsorption of the flip chip 1 is stopped and released, and the heater tool 8 is raised.

In the present embodiment, the air cylinder is used as the actuator for applying the bonding load, but a linear motor may be used instead.

As described above, in the present embodiment, a precisely adjusted bonding load can be applied to the flip chip 1 before heating, so that even if there is an oxide film on the surface of the bump 4, it is destroyed. As a result, reliable flip chip bonding can be performed.

The height of the chip suction means 7 holding the flip chip 1 in the bonding direction is controlled by the heated bumps 4 being rapidly melted or deformed and the chip suction means 7 descending at a high speed. Also, since the mechanical stopper 14 can mechanically stop the lowering of the chip suction portion 7, that is, the lowering of the flip chip 1, the bumps 4 are not crushed too much by an overshoot and short-circuited with the adjacent bumps. Stable flip chip bonding can be performed.

In addition, the flip chip bonding operation can be made possible by the simple mechanism as described above.

Embodiment 2. In the second embodiment, as a means for determining the height of the flip chip 1, the conductive bumps 4 of the flip chip 1 and the conductive bumps of the wiring board 2 are in contact with each other as shown in the first embodiment. With the reference position as the reference position,
Instead, as shown in FIG. 6, a displacement meter 15a of contact type or non-contact type that detects the position of the surface of the wiring board 2 is used.
To set the height α of the bonding head 11 so that the flip chip 1 has a predetermined height when the chip suction means 7 hits the mechanical stopper 14 and stops with the surface of the wiring board 2 as a reference position. Is.
The other points are similar to those of the first embodiment.

Here, in the above-described first embodiment,
If a large bump is unexpectedly formed due to variations in the manufacturing process of the bump, the large bump is formed on the wiring board 2.
The position where the bumps other than the above-mentioned large bumps contact the wiring substrate 2 may be incompletely contacted when the pressing amount ψ that does not consider the variation is pressed.

On the other hand, in the present embodiment, since the surface of the substrate 2 is used as the reference position, the flip chip 1 is set at a certain height from the surface of the substrate 2 without considering the existence of the unexpectedly large bump. Since the bumps are pushed down, the bumps other than the large bumps can be brought into complete contact with the wiring board 2.

[0035]

The flip-chip bonding apparatus according to the present invention is a flip-chip bonding apparatus for electrically connecting a flip-chip to a substrate via conductive bumps formed on the flip-chip. Chip suction means, stop means for mechanically stopping the chip suction means, and driving means in the direction perpendicular to the surface of the substrate, and the chip suction means is movably attached and A bonding head to which a stopping means is fixed, a measuring means for measuring a relative distance between a predetermined portion of the bonding head and a predetermined portion of the chip suction means, a storage means for storing a set value of the relative distance, and a relative distance. Compare the measured value of the distance with the set value of the relative distance, and make sure that the measured value and the set value are equal. Control means for controlling the drive of the bonding head by the drive means so as to stop the bonding head, and after stopping the bonding head by the control means, move the chip suction means to the stop position by the stop means. It is characterized by comprising a pressing means for pressing and moving.

Therefore, a load can be applied to the conductive bumps before heating, and even if an insulating film such as an oxide film is present on the bump surface, it can be destroyed.
Flip chip bonding capable of reliable electrical connection can be realized. In addition, since the lowering of the chip suction means that has sucked the flip chip is mechanically stopped by the stop means, even if the bump is heated and rapidly melted or deformed, and the chip suction means descends at high speed, an overshoot occurs. Therefore, there is no problem that the bumps are crushed too much and short-circuited with the adjacent bumps, and stable flip chip bonding can be performed. Further, flip chip bonding can be enabled by the simple mechanism as described above.

Further, the measuring means measures the relative distance between the predetermined portion of the bonding head and the substrate surface, instead of measuring the relative distance between the predetermined portion of the bonding head and the predetermined portion of the chip suction means. Therefore, even if an unexpectedly large bump is formed due to manufacturing variations of the bump, the flip chip is pushed down to a certain height from the substrate surface. It further has the effect that electrical contact with the substrate is also possible.

Further, since the pressurizing means is an air cylinder, it is possible to apply the set pressure to the bumps with a simple and lightweight mechanism.

Further, since the heating means is provided for heating and melting or deforming the bump while the load is applied to the bump by the pressing means, the bump is loaded before heating by the heating means. Can be applied, and even if there is an insulating film such as an oxide film on the bump surface, it can be destroyed in advance and more reliable electrical connection can be made by melting or deforming the bump. Become.

The flip-chip bonding method according to the present invention is a flip-chip bonding method for electrically connecting a flip-chip to a substrate through conductive bumps formed on the flip-chip. The flip chip is attracted to the chip suction means, and the bonding head is moved in a direction perpendicular to the surface of the substrate, and the relative distance between the predetermined portion of the bonding head and the predetermined portion of the chip suction means is set. The bonding head is stopped at a position equal to the value, and after the bonding head is stopped, the chip suction means is pressed to move in the direction perpendicular to the substrate surface in the substrate direction, and the stopping means fixed to the bonding head is used. At the stop position, mechanically stop the chip suction means. It is characterized in that to.

Therefore, a load can be applied to the conductive bumps before heating, and even if an insulating film such as an oxide film is present on the bump surface, it can be destroyed.
Flip chip bonding capable of reliable electrical connection can be realized. In addition, since the lowering of the chip suction means that has sucked the flip chip is mechanically stopped by the stop means, even if the bump is heated and rapidly melted or deformed, and the chip suction means descends at high speed, an overshoot occurs. Therefore, there is no problem that the bumps are crushed too much and short-circuited with the adjacent bumps, and stable flip chip bonding can be performed.

Further, instead of stopping the bonding head at the position where the relative distance between the predetermined portion of the bonding head and the predetermined portion of the chip suction means becomes equal to the set value as described above, the predetermined portion of the bonding head and the substrate surface are Since the bonding head is stopped at a position where the relative distance of the bumps becomes equal to the set value, even if unexpectedly large bumps are formed due to variations in manufacturing of the bumps, a constant height from the substrate surface can be maintained. In addition, since the flip chip is pushed down, there is the effect that bumps other than the large bumps can be electrically contacted with the substrate.

Further, since the bumps are heated to melt or deform while applying a load to the bumps, higher quality flip chip bonding can be performed.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of essential parts showing an embodiment of a flip chip bonding apparatus according to the present invention.

FIG. 2 is a conceptual diagram showing a mutual relationship among a storage unit, a control unit, a measuring unit, a pressurizing unit, a heating unit and a driving unit, which are components of the flip chip bonding apparatus according to the present invention.

FIG. 3 is a cross-sectional view of an essential part showing the operation of the flip chip bonding apparatus according to the present invention.

FIG. 4 is a cross-sectional view of an essential part showing the operation of the flip chip bonding apparatus according to the present invention.

FIG. 5 is a cross-sectional view of an essential part showing the operation of the flip chip bonding device according to the present invention.

FIG. 6 is a cross-sectional view of essential parts showing another embodiment of the flip chip bonding apparatus according to the present invention.

[Explanation of symbols]

1 flip chip, 2 substrate, 4
Bumps, 5 control means, 6 storage means,
7 chip adsorption means, 8 heating means, 11 bonding head, 12 driving means.

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01L 21/60 311 H01L 21/52

Claims (7)

(57) [Claims] 1. A flip chip bonding apparatus for electrically connecting a flip chip to a substrate through a conductive bump formed on the flip chip, and a chip suction means for sucking the flip chip, and the chip suction means. Stopping means for mechanically stopping, a bonding head driven by a driving means in a direction perpendicular to the surface of the substrate, the chip suction means being movably attached, and the stopping means being fixed. Measuring means for measuring the relative distance between the predetermined portion of the bonding head and the predetermined portion of the chip suction means, storage means for storing the set value of the relative distance, setting of the measured value of the relative distance and the relative distance Compare the value and stop the bonding head at the position where the measured value and the set value are equal, Control means for controlling the drive of the bonding head by the drive means, and pressurizing means for pressing and moving the chip suction means to the stop position by the stop means after the bonding head is stopped by the control means. A flip chip bonding device characterized by being provided. 2. The measuring means, instead of measuring the relative distance between the predetermined portion of the bonding head and the predetermined portion of the chip suction means, measures the relative distance between the predetermined portion of the bonding head and the substrate surface. The flip chip bonding apparatus according to claim 1. 3. The flip chip bonding apparatus according to claim 1, wherein the pressing means is an air cylinder. 4. The flip according to claim 1, further comprising heating means for heating the bump to melt or deform it while applying a load to the bump by the pressing means. Chip bonding equipment. 5. A flip chip bonding method for electrically connecting a flip chip to a substrate through a conductive bump formed on the flip chip, wherein the flip is mounted on a chip suction means movably attached to a bonding head. The chip is sucked, the bonding head is moved in a direction perpendicular to the surface of the substrate, and the bonding is performed at a position where the relative distance between the predetermined portion of the bonding head and the predetermined portion of the chip suction means is equal to a set value. The head is stopped, and after the bonding head is stopped, the chip suction means is pressed to move in the substrate direction perpendicular to the substrate surface, and the chip suction means is stopped at the stop position fixed by the bonding head. Flip chip bonder characterized by mechanically stopping Packaging method. 6. Instead of stopping the bonding head at a position where the relative distance between the predetermined portion of the bonding head and the predetermined portion of the chip suction means becomes equal to a set value, the relative distance between the predetermined portion of the bonding head and the substrate surface is changed. 6. The flip chip bonding method according to claim 5, wherein the bonding head is stopped at a position equal to the set value. 7. The bump is heated to melt or deform while the load is being applied to the bump.
Or the flip chip bonding method according to item 6.