JP5211724B2 - Ball suction head - Google Patents

Description

  The present invention relates to a ball suction head used when a conductive ball such as a solder ball is mounted on a semiconductor chip or a package.

When forming bump electrodes as external connection terminals on packages such as BGA (Ball Grid Array) and CSP (Chip Size Package), or semiconductor chips, a plurality of conductive balls are formed by vacuum suction using a ball suction head. After sucking all at once and moving the ball suction head onto the package or the semiconductor chip, the vacuuming is released and the conductive balls are collectively fed onto the package or the semiconductor chip. .
FIG. 12 is a schematic view showing a solder ball process using a conventional ball suction head. As shown in FIG. 12, the conventional ball suction head is constituted by a ball suction block 12 having a suction hole 12a having a taper in the lower portion and having a decompression chamber 12b therein. The decompression chamber 12b is connected to the vacuum source 14 through a pipe. When mounting a solder ball on the connection terminal of the package, first, the ball suction head is moved onto the solder ball reservoir 7 in which the solder ball 6 is accommodated, and the ball is sucked to a position where the suction hole 12a approaches the solder ball 6. Lower the head. In this state, evacuation is performed from the vacuum source 14, and the inside of the decompression chamber 12b is decompressed. Then, as shown in the figure, the solder balls 6 are sucked into the respective suction holes 12a. The ball suction head is lifted with the solder ball 6 being sucked and moved onto the package 11. A connection terminal 11a is formed on the package 11, and flux (not shown) is applied in advance on the connection terminal 11a. After the ball suction head is positioned so that the solder ball 6 is positioned on the connection terminal 11a, the ball suction head is lowered to a position where the solder ball 6 contacts the connection terminal 11a. Next, the suction of the solder ball 6 is released by releasing the vacuuming by the vacuum source 14, and the solder ball 6 is mounted on the connection terminal 11 a of the package 11. Thereafter, the ball suction head is moved onto the solder ball reservoir 7. On the other hand, the package 11 on which the solder balls 6 are mounted is carried into a reflow furnace and subjected to a reflow process to form solder bumps as external connection terminals on the package.

  By the way, when the solder balls are adsorbed in all of the suction holes 12a (usually present in several hundreds to thousands) formed in the tapered shape, the degree of vacuum in the decompression chamber 12b is increased and the solder balls are strongly sucked. Will be. Since the solder ball 6 is soft, when it is sucked at a high vacuum, it may be deformed as shown in FIG. 13 due to a collision or by being sucked at a high vacuum, and may be fitted into the suction hole 12a. Further, when the ball suction head that sucks the solder balls 6 is lowered onto the package 11, the solder balls are deformed by being pressed between the ball suction head and the package, and may be fitted into the suction holes 12a. . On the other hand, when evacuation is performed at a low vacuum that does not cause deformation of the solder balls, all of the suction holes 12a of the suction block 12 cannot suck the solder balls 6, or it takes time for the suction. End up. When the solder ball 6 fits into the suction hole 12a and is fixed, the solder ball 6 remains in the suction hole 12a without being mounted in the package 11 when mounted on the package 11, and as a result, the solder ball 6 remains in the package 11. The bumps are not formed due to the shortage, and the package 11 becomes defective.

Another problem caused by the vacuum chamber 12b becoming a high vacuum when the solder balls 6 are attracted to the suction holes 12a is that the surface on which the suction holes 12a of the ball suction block 12 are formed is curved. It is difficult to ensure the parallelism between the bottom surface of the ball suction block 12 and the package, and as a result, the mounting position accuracy of the solder ball 6 on the package 11 is lowered.
As a conventional countermeasure against the former problem (problem in which a solder ball fits into a suction hole), for example, Patent Document 1 discloses a technique for processing irregularities in a suction hole of a ball suction head. Yes. Moreover, as a countermeasure against the latter problem (problem in which the flatness of the bottom surface of the ball suction head is impaired), for example, in Patent Document 2, it is formed of a metal foil on a ball array plate in which a large number of suction holes are formed. A ball suction head in which a metal honeycomb body is disposed is disclosed.
JP 2003-086619 A JP 2006-302973 A

In the method described in Patent Document 1, it is necessary to process irregularities on suction holes present in hundreds to thousands of locations, which increases equipment costs and manufacturing costs. Further, the convex portion formed in the suction hole may bite into the solder ball in the opposite direction, and the solder ball may be deformed, and it may be difficult to remove the solder ball from the suction hole when the vacuum is released. Further, in the ball suction head described in Patent Document 2, when the solder ball is sucked, the solder ball comes into contact with the metal honeycomb body functioning as a vacuum air path for sucking the ball, and the solder ball is vacuum air of the metal honeycomb body. There is a possibility of fitting into the path or biting into the metal foil constituting the metal honeycomb body.
The object of the present invention is to solve the above-mentioned problems of the prior art. The purpose of the present invention is to firstly fit the conductive ball into the suction hole of the ball suction head during the ball suction of the ball suction head. Secondly, the flatness of the bottom surface of the ball suction head is not impaired during the ball suction of the ball suction head.

To achieve the above object, according to the present invention, a first mask made of metal, and the first second mask its lower surface is made of metal disposed in contact with the upper surface of the mask, the first An adsorbing block that forms a decompression chamber together with the second mask, and has a frustoconical first opening formed in the first mask and the second mask. A ball suction head configured to suck a conductive ball through a gap formed by an overlapping portion with a plurality of formed second openings, wherein the second opening is disposed on a center line of the first opening. There is provided a ball suction head, wherein the second opening is formed only so as to hang over an end portion of the upper surface of the first opening .

In order to achieve the above object, according to the present invention, a first mask, a second mask arranged with its lower surface in contact with the upper surface of the first mask, and above the second mask are provided. And a suction block that constitutes a decompression chamber together with the second mask, and a first frustoconical opening formed in the first mask and a plurality of second holes formed in the second mask. A ball suction head configured to suck a conductive ball through a gap formed by an overlapping portion with two openings, wherein the first opening is covered by the conductive ball over the entire circumference at the time of suction of the conductive ball. There is provided a ball suction head characterized in that it is not blocked.

  According to the ball suction head of the present invention, the air circulation path is not formed on the center line of the first opening which is the ball suction hole, and the bottom surface of the second mask is formed at the center of the upper surface of the first opening. Will exist. The conductive ball comes into contact with the bottom surface of the second mask at the time of suction, and the possibility that the conductive ball fits into the suction hole is reduced. At the same time, a gap serving as an air flow path is secured between the side surface of the suction hole and the conductive ball, and it is avoided that the decompression chamber of the ball suction head is in an excessively high vacuum state. Curvature of the bottom surface is suppressed. Therefore, according to the present invention, when the evacuation to the ball suction head is released, the possibility that the conductive ball is left on the ball suction head side is reduced, and the occurrence of a defective bump defect is avoided. In addition, when the conductive ball is attracted by the ball suction head, the bottom flatness of the ball suction head can be maintained satisfactorily, and the accuracy of the mounting position of the conductive ball can be improved.

Next, preferred embodiments of the present invention will be described in detail with reference to the drawings.
[First Embodiment]
FIG. 1 is a cross-sectional view showing a ball suction head according to a first embodiment of the present invention, and FIG. 2 is a plan view of the ball suction head according to the first embodiment viewed from the bottom surface side. As shown in FIG. 1, the ball suction head 4 of the present invention includes a first metal mask 1, a second metal mask 2, and a suction block 3. The first metal mask 1 and the second metal mask 2 are formed by etching a metal plate made of stainless steel or the like. As shown in FIGS. 1 and 2, the first metal mask 1 is formed with frustoconical suction holes 1a with a number and pattern corresponding to the number of solder balls to be mounted and the arrangement pattern thereof. ing. In the second metal mask 2, an opening 2a having a diameter equal to the diameter on the bottom surface side of the suction hole 1a of the first metal mask 1 is formed so as to be shifted from the suction hole 1a by a half pitch. The suction block 3 is a metal member having a substantially square cross section, and an air intake hole 3a connected to a vacuum source is opened in the center of the ceiling. The first and second metal masks 1 and 2 and the suction block 3 are combined as shown in the figure by bonding or brazing to form a ball suction head 4. At this time, a decompression chamber 4 a is formed between the second metal mask 2 and the suction block 3. Further, a gap 5 is formed by an overlapping portion between the suction hole 1a of the first metal mask 1 and the opening 2a of the second metal mask 2, and the solder balls are sucked by suctioning through the gap 5. become. If there is a misalignment between the suction hole 1a and the opening 2a, intake air in each suction hole 1a varies, and stable ball suction becomes difficult. Therefore, the first and second metal masks 1 and 2 are attached to each other. It is important to drill holes for forming with high accuracy. Therefore, it is desirable to form the suction holes 1a and the openings 2a by etching.

  FIG. 3 is an enlarged cross-sectional view showing a state in which solder balls are attracted to the ball attracting head of the present embodiment. As shown in the figure, the solder ball 6 comes into contact with the bottom surface of the second metal mask 2 when sucked into the suction hole 1a. Therefore, fitting of the solder ball 6 into the suction hole 1a is avoided. Here, although there is no possibility that the solder ball 6 fits between the suction hole 1a surface and the bottom surface of the second metal mask 2, the inclined surface of the suction hole 1a and the bottom surface of the second metal mask 2 Since the angle formed by is an obtuse angle with a large angle, the possibility is low. Accordingly, it is possible to prevent an accident in which the solder ball 6 is left on the ball suction head side when the solder ball 6 is released from the ball suction head. Further, when the solder ball 6 is sucked, the suction hole 1a of the first metal mask 1 is not blocked by the solder ball 6, and an air flow path is formed between the solder ball 6 and the inner wall of the suction hole 1a. By ensuring, the decompression chamber is not evacuated to an excessively high vacuum state, and the first metal mask 1 is prevented from being bent when the solder ball is adsorbed.

Next, a solder ball mounting operation using the ball suction head 4 of the present embodiment will be described. First, the ball suction head 4 is moved onto the solder ball reservoir 7 in which the solder balls 6 are stored, and then lowered to bring the ball suction head 4 closer to the solder balls 6 in the solder ball reservoir 7. When a vacuum source (not shown) is evacuated, the degree of vacuum in the decompression chamber 4a is increased, and the solder balls 6 are evacuated via the gap 5 between the first metal mask 1 and the second metal mask 2. Sucked. At this time, in order to cause the ball suction head 4 to suck the solder ball 6, the solder ball 6 may be floated by blowing gas from the lower surface of the solder ball reservoir 7 or by vibration. As shown in FIG. 3, when the solder ball 6 is attracted, the upper vertex of the solder ball 6 comes into contact with the plane of the lower surface of the second metal mask 2, and the solder ball 6 is in contact with the first metal mask. There is no contact with the entire circumference of the tapered portion of the one suction hole 1a. Although there is leakage of vacuum air from the gap between the solder ball 6 and the suction hole 1a, the solder ball 6 is held by the ball suction head 4 by vacuum suction. Accordingly, the solder ball 6 is sucked without being fitted into the ball suction head 4. Thereafter, the ball suction head 4 is moved onto a package (not shown) and supplies solder balls onto the connection terminals of the package.
Instead of the method of adsorbing the solder balls from the solder ball reservoir 7 described above, as shown in FIG. 5, the solder balls are once applied to the alignment plate 8 provided with concave holes according to the number and position of the solder balls to be mounted. It is also possible to use a method of aligning 6 and adsorbing solder balls therefrom.

[Second Embodiment]
FIG. 6 is a cross-sectional view showing a ball mounting head according to a second embodiment of the present invention, and FIG. 7 is a plan view of the ball mounting head according to the second embodiment as viewed from below. 6 and 7, parts that are the same as the parts of the first embodiment shown in FIGS. 1 and 2 are given the same reference numerals, and redundant descriptions are omitted as appropriate. As shown in FIGS. 6 and 7, the second metal mask 2 has two openings 2 b at positions away from the center of the suction hole 1 a of the first metal mask 1 by a certain distance. As in the case of the first embodiment, when the solder ball 6 is vacuum-sucked to the ball suction head 4, the upper vertex of the solder ball 6 is the plane on the lower surface of the second metal mask 2. The solder balls 6 are held by the ball suction head 4 without coming into contact with the entire circumference of the tapered portion of the suction hole 1 a of the first metal mask 1. Accordingly, the solder balls 6 are attracted without being fitted into the ball attracting head 4, and the stable mounting of the solder balls can be achieved. Further, since the degree of vacuum in the decompression chamber 4a does not increase excessively, the flatness of the bottom surface of the ball suction head 4 is maintained well during the solder ball suction.

[Third Embodiment]
FIG. 8 is a plan view of the ball mounting head according to the third embodiment of the present invention as viewed from below. 8, parts that are the same as the parts of the second embodiment shown in FIG. 7 are given the same reference numerals, and redundant descriptions will be omitted as appropriate. As shown in FIG. 8, the second metal mask 2 has three openings 2b at positions spaced apart from the center of the suction hole 1a of the first metal mask 1 by a certain distance. As in the case of the first and second embodiments, when the solder ball 6 is vacuum-sucked to the ball suction head 4, the upper vertex of the solder ball 6 is the lower surface of the second metal mask 2. The solder ball 6 is held by the ball suction head 4 without coming into contact with the entire circumference of the tapered portion of the suction hole 1a of the first metal mask 1. Therefore, the same effects as those in the first and second embodiments can be expected.
In the second and third embodiments, two to three openings 2b are opened per suction hole 1a. However, the number may be four or more, and the number of openings 2b is not particularly limited.

[Fourth Embodiment]
FIG. 9 is a sectional view showing a ball suction head according to the fourth embodiment of the present invention. In FIG. 9, members having the same functions as those of the first embodiment shown in FIG. 1 are denoted by the same reference numerals, and redundant description will be omitted as appropriate. In the present embodiment, the second metal mask 2 fixed to the first metal mask 1 is fixed to the suction block 3 but is not fixed to the first metal mask 1. The second metal mask 2 and the suction block 3 are supported by the vertical drive means 10 and are configured to move up and down independently of the first metal mask 1. The second metal mask 2 and the suction block 3 are a space constituted by a first metal mask 1 and an outer frame block 9 fixed to the first metal mask 1 and having a substantially cross-sectional shape in cross section. And is moved up and down in the space. The suction block 3 is provided with an intake / exhaust port 3b connected to be switched between a vacuum source and a vacuum break air supply source (both not shown).

  Next, the operation of the ball suction head 4 according to the fourth embodiment will be described with reference to FIG. First, the second metal mask 2 is in a position in contact with the first metal mask 1. In this state, the ball suction head 4 is moved onto the ball reservoir 7 or the ball alignment plate 8 and lowered as shown in FIG. 4 or FIG. Then, evacuation is performed via the intake / exhaust port 3 b, the atmospheric pressure in the decompression chamber 4 a is lowered, and the solder balls 6 are attracted and held by the ball attracting head 4. Subsequently, the ball suction head 4 is moved onto the package 11 and lowered to bring the solder balls 6 into contact with the connection terminals 11a on the package 11 (FIG. 10A). At this time, the flux is already applied on the connection terminal 11a. Next, the vacuum source connected to the intake / exhaust port 3b is switched to the vacuum break air source, and the vacuum break air is supplied into the decompression chamber 4a for a predetermined time. Thereafter, the second metal mask 2 and the suction block 3 are raised by the vertical drive means 10 while the first metal mask 1 and the outer frame block 9 are fixed [FIG. 10 (b)]. At this time, as shown in FIG. 11A, the solder ball 6 was fitted between the inclined surface of the absorption hole 1 a of the first metal mask 1 and the lower surface of the first metal mask 2. However, when the second metal mask 2 is separated, the fitting is eliminated and the solder ball 6 is normally mounted on the package 11 as shown in FIG. Thereafter, the ball suction head 4 is raised and returned to a predetermined position, and the second metal mask 2 is lowered by the vertical driving means 10, and its lower surface comes into contact with the upper surface of the first metal mask 1.

  Although the present invention has been described above with reference to preferred embodiments, the present invention is not limited to these embodiments, and appropriate modifications can be made without departing from the scope of the present invention. For example, in the embodiment, the opening formed in the second mask is not necessarily circular, and may be a polygon such as a square or a rectangle or an ellipse. In the embodiment, the suction head that sucks the solder ball is described. However, the conductive ball mounted on the package or the like is not limited to the solder ball, and the insulating ball is provided with a metal coating. Also good. Further, the substrate on which the conductive ball is mounted may be any of a package, a wiring board, a semiconductor chip, and the like, and is not particularly limited.

Sectional drawing which shows the ball | bowl adsorption head of the 1st Embodiment of this invention. 1 is a plan view showing a ball suction head according to a first embodiment of the present invention. FIG. 3 is an enlarged cross-sectional view showing a ball suction state by the ball suction head according to the first embodiment of the present invention. Sectional drawing which shows the use condition of the ball | bowl adsorption head of the 1st Embodiment of this invention (the 1). Sectional drawing which shows the use condition of the ball | bowl adsorption head of the 1st Embodiment of this invention (the 2). Sectional drawing which shows the ball | bowl adsorption head of the 2nd Embodiment of this invention. The top view which shows the ball | bowl adsorption | suction head of the 2nd Embodiment of this invention. The top view which shows the ball | bowl adsorption | suction head of the 3rd Embodiment of this invention. Sectional drawing which shows the ball | bowl adsorption head of the 4th Embodiment of this invention. Sectional drawing which shows the use condition of the ball | bowl adsorption head of the 4th Embodiment of this invention. Sectional drawing which shows operation | movement of the ball | bowl adsorption | suction head of the 4th Embodiment of this invention. Sectional drawing for demonstrating the conventional ball mounting apparatus and its operation | movement. Sectional drawing for demonstrating the problem of the conventional ball | bowl adsorption head.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st metal mask 1a Suction hole 2 2nd metal mask 2a, 2b Opening 3 Suction block 3a Suction hole 3b Suction / exhaust port 4 Ball suction head 4a Decompression chamber 5 Gap 6 Solder ball 7 Ball reservoir 8 Ball alignment plate 9 Outer frame block 10 Vertical drive means 11 Package 11a Connection terminal 12 Ball suction block 13 Suction hole 14 Vacuum source

Claims (7)

A first mask made of metal, and the first second mask its lower surface is made of metal disposed in contact with the upper surface of the mask, together with the said In the above the second mask second mask A suction block that constitutes a decompression chamber, and an overlapping portion of a frustoconical first opening formed in the first mask and a plurality of second openings formed in the second mask. A ball suction head configured to suck a conductive ball through a formed gap , wherein the second opening does not exist on the center line of the first opening , and the second opening Is formed so as to be hung only on the end of the upper surface of the first opening . A first mask; a second mask disposed in contact with an upper surface of the first mask; and a suction above the second mask and forming a decompression chamber together with the second mask. And a conductive layer through a gap formed by an overlapping portion of a first opening in the shape of a truncated cone formed in the first mask and a plurality of second openings formed in the second mask. A ball suction head configured to suck a conductive ball, wherein the first opening is not blocked by the conductive ball over the entire circumference at the time of suction of the conductive ball . The ball suction head according to claim 2 , wherein the second opening is formed only so as to be hooked on an end portion of an upper surface of the first opening. The ball suction head according to claim 2, wherein the first mask and the second mask are made of metal. Said first of said second opening of said first opening and said second mask mask, ball according to any one of claims 1 to 4, characterized in that those formed by etching Suction head. It said second mask ball suction head according to any one of claims 1 to 5, characterized in that it is fixed to the first mask. Wherein for the first mask, the ball suction head according to any one of claims 1 to 5, the second mask is characterized in that it is movable up and down together with the vacuum block.

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