JPH10242174A - Bonding head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the production efficiency of a bonding head for pressing and heat electronic components such as semiconductor chips on a substrate, thereby electrically bonding them by suppressing the influence of the positional change due to the thermal expansion of a hot pressing head, etc., accurately mounting the components and reducing the heating and cooling times. SOLUTION: A vertically reciprocally movable drive 28 is actuated to vacuum-hold electronic components 21, press and heat them and electrically bond them on a substrate 20. A heat insulated base 27 has a vacuum chamber 27a connected to a vacuum system and tubular joint 26 has suction long holes 26a communicating with the vacuum chamber 27a. A work holding heater 24 made of a low-heat capacity material is fixed to the other tubular end of the joint 26 and held with the base 27 with leaving a distance which reduces the influence of the temp. distribution of the base 27 on the heater 24 having sucking holes 24a to vacuum-hold the components 21, thus heating them.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bonding head for electrically bonding electronic components such as semiconductor chips on a substrate and mounting the components with high precision.

[0002]

2. Description of the Related Art FIG. 5 shows a conventional example of a bonding head of this kind, in which an electronic component 2 such as a semiconductor chip is mounted on a substrate 1 such as a ceramic substrate and is electrically connected by welding with a solder piece 3. The device is shown. The device is connected to a vacuum system such as a vacuum pump,
It has a heater block 4 for sucking and holding the electronic component 2 by evacuation, and a suction hole 5 is provided along this central axis.
Further, an electric heater 6 is mounted in the heater block 4 in an embedded manner, and the temperature can be adjusted by heating the heater block 4 to a predetermined temperature by detecting the temperature with a thermocouple 7. The heater block 4 is supported by a vertical drive unit 9 via a heat insulating base 8, and can be moved up and down in the vertical direction in the figure by operation.

Accordingly, the solder pieces 3 are set in advance on the mounting position on the substrate 2 and the electronic component 2 is sucked and held by the heater block 4 by the operation of the vacuum system to prepare for mounting by soldering. When the vertical drive unit 9 is lowered,
The electronic component 2 is pressed against the substrate 1 via the solder pieces 3. When the electric heater 6 is turned on in a pressurized state, the electronic component 2 is heated through the heater block 4. After the solder pieces 3 are melted by the heating under pressure, the power supply to the electric heater 6 is turned off. After cooling the electronic component 2 and the heater block 4, the electronic component 2 is joined to the substrate 2 and mounting is completed.

On the other hand, FIG. 6 schematically shows an apparatus disclosed in Japanese Patent Application Laid-Open No. HEI 8-115948 as another conventional example of such a bonding head.

Also in this case, there is provided a pressure bonding head 12 which pressurizes and heats the electronic component 11 mounted on the substrate 10 in a state where the electronic component 11 is suction-held, and the pressure bonding head 12 is supported by a first vertical driving device 13. It can be moved up and down. Also, the second
The vertical drive unit 14 has a support unit 15 attached thereto so as to be vertically movable, and the support unit 15 supports a suction unit 16 in a separable manner. At the center of the suction unit 16, the pressure bonding head 12 of the first vertical drive device 13 side is provided.
Are facing each other, and the electronic component 11 is
6 and is held by suction at the pressure bonding head 12.

Accordingly, the electronic component 11 on the substrate 10
At the time of mounting, the electronic component 11 is sucked and held by the pressure bonding head 12 via the suction portion 16. The electronic component 11 comes into contact with the mounting position on the substrate 10 due to the lowering of the pressure bonding head 12. In substantially synchronism with this, the support portion 15 is integrally lowered by the operation of the second vertical drive device 14. The lowering of the support portion 15 separates the suction portion 16 therefrom. The electronic component 11 is pressurized and heated by the pressure bonding head 12, and is bonded to the substrate 10 and mounted.

[0007]

As shown in the conventional examples of FIGS. 5 and 6, in each case, the following common problem to be solved remains. One problem is that when the electronic component is heated under pressure, a positional change occurs due to thermal expansion of the heater block 4 and the pressure bonding head 12, and the electronic component is displaced from a mounting position. That is, it is often difficult to mount electronic components with high accuracy on a substrate.

One is that the heat capacity of both the heater block 4 and the pressure bonding head 12 is large, the cooling time after heating them by the electric heater becomes long, the tact time is extended, and efficient productivity is desired. Can not do.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an electronic component such as a semiconductor chip as a mounting work under pressure and heat to electrically connect the electronic component to a substrate. It is another object of the present invention to provide a bonding head that suppresses the temperature of the electronic component, enables the electronic component to be mounted with high precision, and shortens the heating time and the cooling time to improve the production efficiency.

[0010]

A bonding head according to the present invention operates an up / down driving device which reciprocates vertically to adsorb and hold an electronic component such as a semiconductor chip as a mounting work and pressurizes and heats it. Therefore, when electrically connecting the substrate to the substrate, a heat-insulating heater mounting base member having a vacuum chamber communicating with a vacuum system and fixed to the vertical driving device, and a suction slot communicating with the vacuum chamber are provided. A connecting member whose cylindrical upper end is connected to the heater mounting base member so that position fluctuations caused by thermal expansion are absorbed, and a cylindrical lower end of the connecting member. A heater made of a material having a small heat capacity, which is fixed and held at a distance from the heater mounting base member at a distance, communicates with the suction slot of the connecting member, and sucks, holds and heats the electronic component by a suction hole provided at the center. It includes a holding heating body.

In this case, the connecting member is directly connected to the heater mounting base member by taper fitting, or is connected to the heater mounting base member by tapering fitting via a ring-shaped heat insulating auxiliary member of a low thermal expansion material. I have.

Further, one end of the cylindrical portion of the connecting portion of the connecting member, which is tapered, can be locked to the heater mounting base member via an elastic member.

Further, the electronic component can be suction-held in a suction hole of the work holding and heating body via a ring-shaped suction piece.

Further, a cooling flow passage for supplying and draining and circulating cooling water to and from the heater mounting base member to maintain a constant temperature can be formed.

[0015] With this configuration, the electronic component is adsorbed and held by the work holding and heating body, and is carried at a position separated by the length of the connecting member from the heat-insulating heater mounting base member. In addition, no displacement occurs due to heat fluctuation. As a result, the electronic component can be mounted on the mounting position of the substrate with high accuracy.

Since one end of the connecting member is fixed to the heater mounting base member by an elastic member such as a leaf spring, even if dimensional distortion occurs due to thermal expansion, the elastic member has an elasticity. Can be absorbed by bending.

Further, by circulating the cooling water through the heater mounting base member, the heater mounting base member as a heat insulating member can always be maintained at a constant temperature.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the bonding head according to the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a sectional view showing the first embodiment. An electronic component 21 such as a semiconductor chip is mounted on a substrate 20 set on a stage by soldering 22.
The thermocompression bonding head 23 constituting the main part of the apparatus is composed of the following members. It has a work holding heating element 24 as a ceramic heater formed in a disc shape from a material such as ceramics having a small heat capacity.
A thermocouple 25 is provided as a temperature detecting means for suppressing the temperature of the thermocouple 4 from rising above a predetermined temperature. In addition, a suction hole 24 penetrating in the plate thickness direction is provided at the center of the circle of the work holding heating element 24.
The electronic component 22 which is a mounting work can be sucked and held by vacuuming from the suction hole 24a.

Further, a connecting member 26 formed in a tapered cylindrical shape that is long in the vertical and vertical directions is provided, and the long suction hole 26a formed by the cylindrical hole along the axis is aligned with the suction hole 24a of the work holding heating element 24 and connected. Then, both members are integrated. The connecting member 26 is connected to a vacuum system including a vacuum pump or the like through a long suction hole 26a. Further, a part of the connecting member 26 in the longitudinal direction is formed as a tapered portion 26b whose outer diameter is gradually reduced, and a rear end portion following the tapered portion 26b is formed as a male screw portion 26c.

The joined body composed of the work holding heating element 24 and the connecting member 26 is carried by a vertical driving device 28 via a heat insulating base 27 of a heater mounting base member according to the present invention. Reciprocating in the vertical direction. The heat insulating base 27 is made of a material having a small heat conductivity and a heat insulating effect, and is formed in a housing shape having a hollow vacuum chamber 27a therein. The tapered portion 26b of the connecting member 26 is taperedly fitted into a tapered hole 27b formed in the bottom wall of the heat insulating base 27.
Further, the male screw portion 26c at the rear end of the connecting member 26 penetrates to the vacuum chamber 27a of the heat insulating base 27, and the nut 31 is screwed into the vacuum chamber 27a via the leaf spring 30 and fixed. The vacuum chamber 27a is connected to a vacuum system (not shown) including a vacuum pump and the like through a vacuum pore 27c and a vacuum tube 27d.

Next, the operation and operation of the bonding head according to the first embodiment having such a configuration will be described.

The substrate 20 is set on the stage, and the electronic component 21 is set at the work mounting position with the solder 22 interposed therebetween to start the mounting operation. By the operation of the vacuum system, the vacuum chamber 27a in the heat insulating base 27 is made negative pressure,
The electronic component 21 includes a work holding heating element 24 and a connecting member 26.
Is sucked through each of the suction holes 24a and 26a.

When the power is turned on, the work holding heating element 24 is turned on.
Is heated, and the held electronic component 21 is also heated. It is assumed that the tubular connecting member 26 undergoes thermal expansion due to the heating action during this time. In this case, the thermal expansion of the connecting member 26 in the axial direction is absorbed by the elastic bending of the leaf spring 30. By this expansion absorbing action, it is possible to prevent the connecting member 26 from being displaced due to loosening with respect to the heat insulating base 27.

The electronic component 21 is vacuum-adsorbed on a central axis of a work holding heating element 24 having a small heat capacity as a ceramic heater. The thermal expansion of the work holding heating element 24 is
Theoretically, on the central axis, that is, on the suction hole 24a, ±
0 means no occurrence. But actually,
In order to be affected by the temperature distribution etc. on the heat insulating base 27 side,
There are some thermal fluctuations. Even in this case, the work holding heating element 24 is located at a distance apart by the length of the connecting member 26, so that the influence of heat fluctuation is small and can be suppressed to a very small amount. In addition, since the electronic component 21 is directly held and heated by the work holding heating element 24 having a small heat capacity, rapid heating can be performed and cooling can be performed in a short time.

The operation of the vertical drive device 28 lowers the thermocompression bonding head 23, and is bonded by the melted solder 22.
The electronic component 21 is thermocompression-bonded to the substrate 20. In the meantime, the above-described feature of suppressing the thermal fluctuation prevents the electronic component 21 from being displaced, thereby enabling high-precision mounting.

Next, FIG. 2 shows a second embodiment of the bonding head according to the present invention. In this case, the first of FIG.
A ring-shaped suction collet 32, which is a suction piece according to the present invention, is interposed between the disk-shaped workpiece holding / heating body 24 and the electronic component 21 shown in the embodiment, and the electronic component 21 is provided.
This is a mode in which is held by suction.

The outer diameter of the suction collet 32 is set substantially in accordance with the size and shape of the electronic component 21. The suction hole 32a of the suction collet 32 is set to coincide with the center of the coaxial hole of the center suction hole 24a of the work holding and heating body 24. The other members are the same as the members in the first embodiment, and the corresponding members are denoted by the same reference numerals, and redundant description will be omitted.

Therefore, in the second embodiment, since the suction collet 32 is provided, the following advantages can be obtained as compared with the first embodiment in which the work holding and heating body 24 is suction-held on the disk surface.

The electronic component 21 is heated and held by suction through a suction collet 32 of substantially the same shape. In this case, it becomes easy to cope with an electronic component having a shape and a size that cannot be adsorbed on the disk surface of the work holding and heating body 24. Further, when another electronic component is already mounted on the substrate 20, interference with the existing electronic component can be avoided by the space where the suction collet 32 is interposed. Furthermore, since the electronic component 21 can be heated with a minimum contact area via the suction collet 32 having substantially the same shape, rapid heating can be performed with a small heat capacity, and an excellent advantage that the cooling time can be shortened accordingly can be obtained.

FIG. 3 shows a third embodiment of the bonding head according to the present invention. In this case, FIGS. 1 and 2
The structure utilizes both advantages of the first and second embodiments shown in FIG. That is, also in this case, the suction collet 32 that is interposed between the electronic component 21 and the suction collet 32 is provided.

The connecting member 26 has a structure in which it is taperedly fitted to a heat insulating base 27 via a ring-shaped heat insulating auxiliary seat 33 which is a heat insulating auxiliary member having a tapered portion on the outer peripheral portion. As a material of the heat insulation auxiliary seat 33, a low thermal expansion material such as quartz glass is used. A ring-shaped inner ring peripheral side has a tapered hole 33a into which the tapered portion 26b of the connecting member 26 fits, and a tapered portion 33b taper-fitted into the heat insulating base 27 is formed on the outer ring peripheral side. Have been. Therefore, the heat insulating base 27 is provided with a tapered hole 27b into which the heat insulating auxiliary seat 33 is tapered.
The other members are the same as the members in the first and second embodiments, and corresponding members are denoted by the same reference numerals, and redundant description will be omitted.

Therefore, by adopting a structure in which the connecting member 26 is taperedly fitted to the heat insulating base 27 via the heat insulating auxiliary seat 33, the influence of the temperature distribution on the heat distribution is reduced as compared with the case where only the heat insulating base 27 is used alone. It is effective for further deterrence.

FIG. 4 shows a fourth embodiment of the bonding head according to the present invention. In this case, a water guide pipe 34 and a drain pipe 35 for a coolant such as water are provided.
A structure in which a cooling flow path 36 and an annular cooling flow path 37 communicating with the cooling flow path 36 are formed in the heat insulating base 27 so as to be connected between the two pipes. Other members are the same as the members in the first to third embodiments, and corresponding members are denoted by the same reference numerals, and redundant description will be omitted.

During use, cooling water or the like indicated by an arrow
And the cooling water is discharged from the drain pipe 35 through the cooling flow passage 36 and the annular cooling flow passage 37. Meanwhile, the heat insulating base 27 is cooled by the circulating cooling water and is maintained at a constant temperature.

As a result, the influence of the temperature distribution on the heat insulating base 27 is also eliminated or minimized. Therefore, similarly to the case shown in each of the above-described embodiments, prevention of displacement of the electronic component 21 caused by the influence of the temperature distribution and the like,
Further, the electronic component 21 can be rapidly heated and cooled for a short time.

[0037]

As described above, in the bonding head of the present invention, in the bonding head, the electronic component as the mounting work is such that the work is located at a position separated by the length of the connecting member from the heat insulating base as the heat insulating base member for mounting the heater. Since it is adsorbed and held by the holding heating body, the influence of the temperature distribution is small, and no positional shift occurs due to heat fluctuation. As a result, even when the electronic component needs to be heated and cooled in a pressurized state, the electronic component can be mounted on the mounting position of the substrate with high accuracy.

Further, the work holding and heating body is formed in a disk shape having a small heat capacity, so that the electronic component is directly heated, so that rapid heating is possible, and the cooling time can be shortened, so that the tact time can be shortened, and the temperature can be greatly reduced. High productivity can be expected.

[Brief description of the drawings]

FIG. 1 is an assembly view with a partial cross section showing a first embodiment of a bonding head according to the present invention.

FIG. 2 is an assembly view with a partial cross section showing a second embodiment.

FIG. 3 is an assembly view with a partial cross section showing a third embodiment.

FIG. 4 is an assembly view with a partial cross section showing a fourth embodiment.

FIG. 5 is an assembly view with a partial cross section showing a conventional bonding head.

FIG. 6 is an assembly view showing another conventional bonding head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 20 Substrate 21 Electronic component of mounted work 22 Solder 23 Thermocompression bonding head 24 Work holding heating element 24a Suction hole 26 Connecting member 26a Suction long hole 26b Taper fitting portion 26c Male screw portion 27 Heat insulating base (heater mounting base member) 27a Vacuum chamber Reference Signs List 28 vertical drive device 30 leaf spring (elastic member) 31 nut for fastening and fixing connecting member 32 suction collet (suction piece) 33 heat-insulating auxiliary seat 36 cooling flow passage 37 annular cooling flow passage

Claims (6)

[Claims] An electronic device such as a semiconductor chip, which is a mounting work, is attracted and held, and heated and pressurized by operating a vertical driving device that reciprocates in a vertical direction so as to be electrically bonded to a substrate. A bonding head having a vacuum chamber that communicates with a vacuum system, a heat-insulating heater mounting base member fixed to the vertical drive device, and a suction elongated hole communicating with the vacuum chamber. A connecting member having a cylindrical upper end connected to the heater mounting base member to absorb a position change caused by thermal expansion; and the heater fixed to the cylindrical lower end of the connecting member. A work holding and heating body of a material having a small heat capacity, which is held at a distance from the mounting base member, communicates with the suction elongated hole of the connecting member, and suction-holds and heats the electronic component by a suction hole provided at the center thereof; Equipped Bonding head, characterized in that there. 2. The bonding head according to claim 1, wherein said connecting member is connected to said heater mounting base member by taper fitting. 3. The bonding head according to claim 2, wherein a cylindrical upper end of the connecting member is locked to the heater mounting base member via an elastic member. 4. The heater connection base member according to claim 2, wherein said connecting member is a ring having a tapered fitting portion, and is connected to said heater mounting base member through a heat insulating auxiliary member made of a low thermal expansion material. Or the bonding head according to 3. 5. The electronic component according to claim 1, wherein said electronic component is sucked and held in said suction hole of said work holding and heating body via a ring-shaped suction piece having substantially the same size and shape as said electronic component. The bonding head according to any one of the above. 6. A cooling flow passage for supplying and discharging cooling water to and circulating the cooling water from the heater mounting base member to maintain the temperature at a constant temperature. Bonding head.