JP2006302973A - Ball arranging head of ball mounting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten a suction time by equalizing a suction quantity in an entire suction area, and to stably and collectively arrange a large number of conductive balls on a large-area wafer. <P>SOLUTION: The conductive balls 10 in a container 8 are sucked and arranged on a ball arrangement plate 6 having a uniform thickness, and then, the conductive balls 10 are collectively mounted on an electrode of an object to which the balls 10 are mounted. A ventilating member including a metal honeycomb body 11 is arranged in a head 1 so as to be directly connected to the rear surface of the plate 6, the member 11 being formed so that a flat foil having a thickness smaller than the diameter of each of suction holes 7 provided on the plate 6 and a corrugated foil obtained by applying corrugation processing to a flat foil are alternately laminated or rolled together and the flat foil is joined to the corrugated foil, and thus, the plate 6 is supported against an external force. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a conductive ball suction array jig and an array mounting device, and more particularly, a plurality of fine balls are collectively held on a ball array plate in which a plurality of ball suction holes are formed, and a wafer or a printed circuit board. The present invention relates to a ball array head of a ball mounting apparatus that is mounted collectively on electrodes of electronic components such as semiconductor chips.

  Recently, ball bumps using fine conductive balls have been used for electrical connection of semiconductor chips. By using the ball bumps, it is possible to obtain a number of merits such as downsizing the package and increasing the number of pins. A bump forming technique using such a fine conductive ball is described in Patent Document 1, for example.

  In the bump forming method described in Patent Document 1, at least one metal ball group corresponding to a semiconductor chip is sucked and held. In order to suck and hold a plurality of metal ball groups, a ball array plate in which suction holes are formed at all positions corresponding to bump formation positions on the semiconductor chip is used. After the fine metal spheres are attracted and held on the ball array plate, the ball array plate is transported to the mounting stage and transferred to the mounted portion.

  According to this method, since the uniformly formed fine conductive balls can be bonded together at the bump forming position, it is possible to easily and efficiently form a ball bump with high reliability.

  By the way, recently, the miniaturization of semiconductor devices has progressed, and the wiring pitch of electrodes has become extremely small. For this reason, the fine conductive balls used for forming ball bumps on the electrodes have become extremely fine as the wiring pitch of the electrodes becomes finer. On the other hand, the number of electrodes is increasing for the purpose of improving the performance of the chip, and the number of balls that are collectively attracted to form bumps is also increasing.

In such a situation, performing the arrangement for one semiconductor chip makes the process complicated and has a large demerit in terms of cost and time. For this reason, before the wafer is cut into individual chips, that is, before the dicing process is performed, ball bumps are arranged on all electrodes corresponding to a plurality of chips on the wafer. .

  Conventionally, as an array head used to collectively arrange ball bumps on all the electrodes on such a wafer, Patent Document 2 does not correspond to the ball array plate and the suction holes of the ball array plate. A support plate having a gas conduction path and supporting the ball arrangement plate from an external force; and a breathable intermediate gas conduction member disposed in a suction area of the ball arrangement plate between the ball arrangement plate and the support plate. An arrangement head in the ball mounting apparatus characterized by this, or an arrangement head in which an intermediate gas conduction member between the ball arrangement plate and the support plate is omitted by providing a protrusion on the ball arrangement plate is disclosed.

  In addition, as an arrangement head used for collectively arranging ball bumps on electrodes on an IC chip, Patent Document 3 discloses a plate thickness between a ball arrangement plate and a suction opening corresponding to a support plate. An array head is disclosed in which an intermediate plate made of a porous material having air permeability in the direction is provided.

JP 7-153765 A Japanese Patent Laid-Open No. 2001-15898 JP-A-4-65848

  However, in the case of a three-dimensional arrangement head of a ball arrangement plate and a support plate and an intermediate gas conducting member (in the example of the above-mentioned patent document, a high-tensile resin net or a porous material), The problem that the suction failure that the ball cannot be sucked occurs and the time for the time for the alignment to the array plate takes a long time is also caused. In the ball mounting process, the ball is not transferred to the mounted portion and remains on the array plate. There was a problem. In addition, when the intermediate gas conduction member between the ball array plate and the support plate is omitted by providing a protrusion on the ball array plate, there is a problem that the yield decreases due to the occurrence of defects in the manufacture of the ball array plate. there were.

  The cause of the suction failure is that the support plate is provided with a gas conduction path that does not correspond to the suction hole, but there is a possibility that the suction hole of the ball array plate may be blocked because there is a thick part other than the conduction path. In addition, an intermediate plate such as a high-tensile resin net or a porous material is required. For this reason, the gas conduction path becomes complicated, the suction resistance is large, and the suction pressure is different due to the holes of the ball array plate, and the suction failure in which the balls cannot be attracted easily occurs. As another problem, when using a high-tensile resin net, a step occurs because the ball array plate is supported by dots or lines, and sufficient parallelism and flatness can be secured when mounting the ball on the electrode. There was a possibility of causing poor mounting of the ball.

  On the other hand, when the gas conduction member between the ball arrangement plate and the support plate is omitted by providing a protrusion on the ball arrangement plate, the complexity of the gas conduction path is avoided. An additional step is required to provide the protrusion, and the suction hole is a small hole, which causes a defect. Furthermore, since a very high protrusion cannot be provided, the gas conduction path becomes a narrow gap, and an increase in suction resistance is inevitable.

  The present invention has been made to solve such problems. The suction amount is made uniform over the entire suction area of the large area, the time required for suction is shortened, and the parallelism and flatness are improved. It is an object of the present invention to provide an array head of a conductive ball mounting device capable of stably arranging a large amount of conductive balls on a large area wafer in a lump.

  The ball array head according to the present invention has a ball array mounting in which the conductive balls in the container are sucked and arrayed on a ball array plate having a uniform thickness, and then the conductive balls are mounted collectively on the electrodes of the object to be mounted. A ball array head of the apparatus, wherein a flat foil having a thickness less than a diameter of a suction hole provided in the ball array plate and a corrugated foil obtained by corrugating the flat foil are alternately laminated or combined in the head A breathable member including a metal honeycomb body formed by winding and joining the flat foil and the corrugated foil is disposed in direct contact with the rear surface of the ball array plate, and supports the ball array plate from an external force. It is a ball arrangement head of a ball mounting device.

  The metal honeycomb body may be a ball array head of a ball mounting apparatus in which the metal honeycomb body is fitted into a ring member.

  Alternatively, it is a ball array head of a ball mounting device in which an ultrasonic transducer is mounted on the ring member.

  Alternatively, in the ball arrangement head of the ball mounting apparatus, the flat foil and the corrugated foil are thicker at the other end than at the end face contacting the ball arrangement plate.

  According to the present invention, even in a large mounting area, the ball adsorption arrangement can be surely improved, the ball mounting yield can be improved, and minute conductive bumps can be formed on the electrodes to be bumped with high accuracy. it can.

Hereinafter, preferred embodiments of a ball array head according to the present invention will be described with reference to the drawings. In addition, this Embodiment is an example and does not limit the range.
Here, FIG. 1 shows an example of a conventional ball adsorption process. With the conductive balls 10 jumped by the vibration of the ball container 8, the arrangement head 1 is brought close to the ball container 8. The array head 1 is connected to a vacuum generation source (not shown), and decompresses the decompression space 2. A gas conduction hole 4 is formed in the array plate support part 3 and connects the suction hole 7 of the array plate 6 fixed by the array plate pressing jig 9 and the decompression space 2 with the intermediate gas conduction member 5 interposed therebetween. . Due to the decompression by these paths, the jumping conductive balls 10 are adsorbed to the adsorption holes 7 of the array plate.

  By the way, the array plate support 3 is generally made of a rigid material so that the array plate and the wafer are kept parallel to suppress deformation against the load applied when the balls are mounted on the wafer electrode. It is done. Therefore, in order to reduce the gas conduction resistance at the time of adsorption, it is preferable to open many through holes. However, in order to ensure rigidity, the number of holes and the opening area are limited. In reality, in order to satisfy such conflicting requirements, the maximum holes that can ensure rigidity are opened, the adsorption holes 7 of the array plate are not blocked, and the gas conduction resistance during adsorption is reduced. An intermediate gas conducting member 5 is used.

  Next, an example of the arrangement head of the present invention is shown in FIG. With the conductive balls 10 jumped by the vibration of the ball container 8, the arrangement head 1 is brought close to the ball container 8. The array head 1 is connected to a vacuum generation source (not shown), and decompresses the decompression space 2. In FIG. 1, the metal honeycomb body 11 corresponding to the array plate support portion has a large number of gas conduction holes, and connects the suction holes 7 of the array plate 6 fixed by the array plate pressing jig 9 and fixed to the decompression space 2. It is out. Due to the decompression by these paths, the jumping conductive balls 10 are adsorbed to the adsorption holes 7 of the array plate. Since the metal honeycomb body 11 is made of a foil that is thinner than the suction holes, the decompression chamber 2 is directly connected to the suction holes of the array plate 6 opened at any position, and suction loss is reduced. Very small.

  By the way, as shown in FIG. 3, the metal honeycomb body 11 mainly includes a strip-shaped flat foil 12 having a thickness of 10 μm to 70 μm, and a strip-shaped corrugated foil 13 obtained by corrugating the flat foil 12, and a winding shaft. It is wound around and manufactured in a spiral shape. The band-shaped corrugated foil 13 has ridges 14 of each wave formed in the width direction, and the cylindrical metal honeycomb body 15 wound in a spiral shape has a large number of air holes 16 in the axial direction of the column. is doing. In addition, as a method for joining the foils inside the metal honeycomb body, a Ni-based powder brazing agent is fixed to the contact portion of the metal flat foil or metal wave foil with an organic substance such as a binder interposed, and brazed in a vacuum furnace. A flat foil and a corrugated foil are subjected to heat treatment or heat treatment of the obtained metal honeycomb body under treatment conditions of a treatment temperature of 1100 ° C. to 1250 ° C., a treatment time of 30 minutes to 90 minutes, and an ultimate vacuum of 0.04 Pa to 0.0065 Pa. The contact portion is solid diffusion bonded or the like.

As a metal foil constituting the metal honeycomb body, for example, a high heat-resistant ferritic stainless steel made of Cr—Al—Fe is often used because it is generally subjected to heat treatment, but other metals are not problematic. The area of the vent holes of a suitable honeycomb body, in terms of support and breathable sequences plate is 0.25 mm ² ~ 1 mm ^2.

  Furthermore, the metal honeycomb body 15 may be incorporated into a metal outer cylinder 17 as shown in FIG. Further, in order to increase the accuracy when assembling into the apparatus, as shown in FIG. 5, after being fitted into the ring member 18, processing for ensuring the flatness of the surface can be performed.

  FIG. 6 shows another embodiment of the present invention. In general, in the ball adsorbing process, the balls are often adsorbed excessively due to air leakage from the array plate 6 or slight contamination of the balls. For this reason, a technique for efficiently removing only surplus balls has been performed by applying ultrasonic vibration to the array plate through the array plate support. In this example, the metal honeycomb body is fitted into the ring member 18 whose inner diameter is larger than the adsorption area, and the ultrasonic vibration unit 19 is installed in the ring member, thereby realizing efficient transmission of ultrasonic waves to the entire metal honeycomb body. To do. At this time, the thickness of the foil other than the portion in contact with the array plate is increased by plating or coating, and the joint is solidified to suppress the attenuation in the foil inside the metal honeycomb body or the joint. it can. At this time, the preferred thickness of the thickened foil is 1.2 to 1.8 times the original foil thickness in terms of suppression of attenuation and air permeability.

  FIG. 7 shows still another embodiment of the present invention. In this example, in order to maintain the flatness of the metal honeycomb body when the ball is transferred onto the wafer, the reinforcing member 20 is installed in the central portion that is particularly easily deformed. As a result, parallel flatness is ensured even when stress is applied to the array plate, and at the same time, there is an advantage that vibration from an ultrasonic vibration unit (not shown) efficiently reaches the center.

  FIG. 8 shows still another embodiment of the present invention. In this example, the arrangement plate, the ring fitting member, and the metal honeycomb body are integrated by joining the arrangement plate to the ring fitting member. Thereby, the flow of the gas flowing from the periphery of the ball container at the time of adsorbing the ball becomes smooth, and the ultrasonic vibration directly propagates to the array plate, thereby increasing the effect of removing excess balls. In addition, by giving tension to the array plate, when the decompression space 2 is switched to positive pressure when the ball is mounted, it is possible to suppress the ball mounting position from being displaced or overloading due to the array plate itself being bent. There is also an effect.

  FIG. 9 shows a schematic configuration of a ball mounting apparatus incorporating the arrangement head of the present invention. In this configuration, the semiconductor substrate or wafer 27 moves while being fixed on the ball mounting stage 26 along the wafer transfer path perpendicular to the paper surface (Y direction), and waits at a predetermined position. A guide or guide rail 24 is installed along a direction (X direction) orthogonal to the wafer transfer path, and the array head 1 movable in the X-Z direction is supported on the guide rail 24.

  On one end side of the guide rail 24, the ball supply device 21 is disposed so as to be positioned below the arrangement head 1. The ball supply device 21 includes a ball storage container 8 that stores a considerable amount of the conductive ball 10, and a vibrator 22 that vibrates the ball storage container 8 and causes the conductive ball 10 to jump in the ball storage container 8. It is out.

  Between the ball supply device 21 and the ball mounting stage 26, an arrangement defect ball removing mechanism 23 and an arrangement inspection mechanism 25 are arranged. The misaligned ball removal mechanism 23 removes misaligned balls in the array head 1 by suction or gas blowing. Further, the arrangement inspection mechanism 25 inspects a ball arrangement defect in the arrangement head 1.

  The array head 1 reciprocates between the ball supply device 21 and the ball mounting stage 26, but is connected to a negative pressure or a vacuum source (not shown). It is supposed to be. It is also possible to change the valve from the negative pressure to the positive pressure during the ball mounting process. Furthermore, the array head 1 is provided with a vibration generation source (not shown) such as an ultrasonic vibrator, and by conducting vibration after completion of the ball adsorption process and adsorption, the conductivity adsorbed excessively in addition to the adsorption holes 6 Ball generation can be suppressed. A ball array plate 6 having suction holes 7 corresponding to electrode portions on the wafer 27 is mounted on the array head.

In the above configuration, the process operation from when the ball array head 1 starts to adsorb the balls until the conductive balls 10 are mounted on the wafer to be mounted will be described.
In the ball supply device 21, the conductive ball 10 in the ball container 8 is jumped by the vibrator 22. As shown by the dotted line in FIG. 9, the ball array head 1 is lowered to a predetermined height on the ball container 8, and the jumping conductive balls 10 are adsorbed.

  Next, after attracting the conductive balls 10, the ball array head 1 moves up and moves to the ball mounting stage 26 along the guide rail 24. During this movement, the defective ball is removed. Thereafter, the arrangement inspection mechanism 25 moves in the Y direction, and inspects the ball adsorption state over the entire arrangement surface of the ball arrangement plate 6. If the inspection result is good, the robot moves to the ball mounting stage 26. In addition, if an alignment defect is found during this inspection, it is possible to return to the position of the ball removal mechanism 23 and remove the defective ball.

  Next, the alignment head 1 is aligned with the wafer 27 waiting on the ball mounting stage 26. Then, by lowering the array head 1, the conductive balls 10 adsorbed on the ball array plate 6 are mounted on the electrode portions of the wafer 27 to which the flux has been applied.

  The ball array head 1 is configured such that the mounting load when contacting the wafer 27 can be controlled in accordance with the type of conductive balls. As a result, the conductive ball 10 can be brought into contact with the wafer 27 with an optimum load, and the conductive ball 10 can always be mounted appropriately and smoothly. Further, as described above, the ball array head 1 is provided with a vibration generation source (not shown), and the conductive ball sucked into the suction hole 6 can be easily released from the suction hole by applying vibration during the ball mounting process. Can do.

Examples are shown below.
Common implementation conditions:
Conductive balls used: 80μmφ, Sn-3Ag-0.5Cu solder Target wafer: 8 inches (200mm), total number of electrodes: 652,288, number of electrodes: 784 / chip, number of chips: 832 / wafer Ball array plate: plate Thickness: 80 μm, adsorption hole diameter: 60 μmφ, total number of adsorption holes: 652,288 adsorption operation time: 90 seconds Additional ultrasonic vibration frequency: 80 kHz to 132 kHz

Conditions for Examples 1 to 4:
Metal honeycomb body: foil thickness 18μm, wave foil wave height 1.25mm, wave pitch 2.54mm, foil width 20mm Outer tube: thickness 1.5mm, inner diameter 220mm, axial height 20mm
Ring member: outer diameter 250mm, thickness 20mm
Example 4 conditions:
Conditions for a comparative example in which the ball array plate was joined to the ring member using an adhesive:
Array plate support: Thickness 15mm, outer diameter 250mm, gas conduction hole diameter 3.5mmφ, gas conduction hole pitch 5mm
Intermediate gas conduction member: 400 mesh metal mesh (65.5μm mesh opening)

  Table 1 shows the number of errors that occurred in a series of suction and mounting operations under the above conditions. In any of the examples, the number of errors was significantly reduced as compared with the comparative example which is a conventional suction head.

  Although the solder balls used in the above examples are only 80 μmφ, the same test was conducted for other ball sizes of 100 μmφ and 150 μmφ, and the arrangement head of the present invention cannot be achieved by the conventional arrangement head. The same good results are obtained.

It is sectional drawing which shows the example of the conventional arrangement | sequence head. It is sectional drawing which shows the ball | bowl arrangement | positioning head of this invention. It is a figure which shows the metal honeycomb body which concerns on this invention. It is a figure which shows the metal honeycomb body which concerns on this invention. It is a figure which shows the metal honeycomb body which concerns on this invention. It is sectional drawing which shows the ball | bowl arrangement | positioning head of this invention. It is sectional drawing which shows the ball | bowl arrangement | positioning head of this invention. It is sectional drawing which shows the ball | bowl arrangement | positioning head of this invention. It is a figure which shows schematic structure of the ball | bowl arrangement | sequence apparatus which concerns on this invention.

Explanation of symbols

1: Array head
2: decompression space
3: Array plate support
4: Gas conduction hole
5: Intermediate gas conduction member
6: Array board
7: Adsorption hole
8: Ball container
9: Array plate holding jig
10: Conductive ball
11: Metal honeycomb body
12: Flat foil
13: Wave foil
14: Ridge line
15: Cylindrical metal honeycomb body wound in a spiral
16: Vent
17: outer cylinder
18: Ring member
19: Ultrasonic vibration part
20: Reinforcing member
21: Ball feeder
22: Exciter
23: Arranged ball removal mechanism
24: Guide rail
25: Sequence check mechanism
26: Stage with ball
27: Wafer

Claims (4)

A ball array head of a ball array mounting device that collectively mounts the conductive balls in a container on the target electrode to be mounted after the conductive balls in the container are sucked and arrayed on a ball array plate having a uniform thickness. ,
In the ball array head, a flat foil having a thickness less than the diameter of the suction hole provided in the ball array plate and a corrugated foil obtained by corrugating the flat foil are alternately laminated or wound together, and the flat foil and the wave are wound together. A ball arraying head for a ball mounting apparatus, wherein a breathable member including a metal honeycomb body formed by joining foils is disposed in direct contact with the rear surface of the ball array plate and supports the ball array plate from an external force. .   The ball arrangement head of the ball mounting apparatus according to claim 1, wherein the metal honeycomb body is fitted into a ring member.   The ball arraying head of the ball mounting apparatus according to claim 2, wherein an ultrasonic transducer is attached to the ring member.   The ball arrangement head of the ball mounting apparatus according to any one of claims 1 to 3, wherein the flat foil and the corrugated foil are thicker at the other end than at an end surface in contact with the ball arrangement plate.

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