JP2008004775A - Ball mounting apparatus and control method thereof - Google Patents

Abstract

Provided is a ball mounting apparatus that can maintain a constant distance between a mask and a substrate using a flat mask.
A ball mounting apparatus 1 includes a plurality of holes 21 filled with a conductive ball B and a predetermined upper surface 100a of a substrate 100 through a mask 20 made of a magnetic body or a material containing a magnetic body. The conductive ball B is disposed at the position. The ball mounting apparatus 1 is a head 30 for moving the conductive ball B on the mask 20, and includes a head 30 including an adsorption portion 34 that moves in a state of being attracted to the mask 20 by magnetic force, And a moving device 40 that moves the head 30 so that the distance between the portion 34 and the upper surface 100a of the substrate 100 is constant.
[Selection] Figure 1

Description

  The present invention relates to a ball mounting apparatus and a control method therefor for arranging minute balls at predetermined positions on a substrate.

  When mounting a semiconductor device such as an LSI (Large Scale Integration) or the like, a conductive minute ball is used to obtain an electrical connection. As a method for mounting conductive microballs on a semiconductor wafer or an electronic circuit board, a method using a mask having a plurality of holes with a diameter through which the microballs penetrate is known.

  Patent Document 1 discloses an array device using a soft magnetic mask. The mask has an opening and a non-opening. The opening is formed in a size that allows the conductive ball to be inserted. On the lower surface (surface on the wafer side) of the non-opening portion, a convex portion is formed so that flux does not easily adhere to the mask when the mask is superimposed on the wafer.

On the other hand, a permanent magnet is provided below the mounting table for mounting the wafer. In this arrangement apparatus, the wafer is fixed to the mounting table by operating the vacuum pump. Further, the mask is closely fixed to the upper surface of the wafer via the convex portion by the magnetic force of the permanent magnet, and in this state, conductive balls are arranged on the wafer via the mask.
JP 2006-5276 A

  One object of the present invention is a ball mounting apparatus and a control method therefor, for example, for disposing a minute ball having a diameter of 1 mm or less at a predetermined position on a substrate, and in particular, a semiconductor device, an optical device, an integrated device It is an object of the present invention to provide a ball mounting apparatus and a control method thereof suitable for disposing conductive minute balls on a substrate when manufacturing a circuit device or a display device.

  In the technique described in Patent Document 1, the lower surface of the mask is attracted and fixed to the upper surface of the substrate via a convex portion. That is, the height of the mask (positioning of the mask and the substrate) is adjusted based on the lower surface of the mask and the lower end of the convex portion in contact with the substrate. For this reason, in an extreme case, the upper surface of the mask may be concave or convex. Therefore, when a minute ball is transferred to the substrate through the mask, it is also important to match the upper surface of the mask with the top level of the minute ball mounted on the substrate. For example, if the upper surface of the mask is recessed, the top of the minute ball may stick out from the mask and be scraped out by a squeegee for moving the minute ball. If the upper surface of the mask is convex, there is a possibility that a minute ball enters between the mask and the substrate and becomes a lost ball. Therefore, there is a demand for a ball mounting apparatus capable of adjusting the height of the mask (positioning of the mask and the substrate) with reference to the upper surface of the mask.

  In recent years, device integration has progressed, and accordingly, conductive microballs that serve as electrodes tend to be further miniaturized. Therefore, in order to reduce mistakes when mounting microballs on the substrate, ensuring the accuracy of the mask is one of the important factors. On the other hand, in recent years, there is also a demand for providing a certain gap between the mask and the substrate for reasons such as not wanting the flux to adhere to the mask. One of the methods is a method in which convex portions are formed in a predetermined pattern on the lower surface of the mask as described in Patent Document 1. In addition to the fact that it is difficult to flatten the top surface, a mask with convex portions formed in a predetermined pattern on the bottom surface ensures a non-uniform structure on the lower side, ensuring the reliability of the accuracy of the structure. Is difficult. In addition, the mask having a complicated structure is likely to be expensive, and further includes a problem that it is difficult to clean the back side (lower side). Unlike the above, in terms of cost and cleaning, it is desirable that the mask has a flat plate shape in which the upper surface and the lower surface are flat surfaces.

  According to one embodiment of the present invention, a microball is arranged at a predetermined position on one surface of a substrate through a mask made of a magnetic body or a material containing a magnetic body, which includes a plurality of holes filled with the microball. It is a ball mounting device for this. This ball mounting apparatus is a head for moving a minute ball on a mask, and includes a head having a suction portion that moves while being attracted to the mask by a magnetic force, and one surface of the suction portion and the substrate. And a moving device that moves the head so that the distance between the head and the head is constant.

  According to this ball mounting device, the head is moved so that the distance between the suction portion and one surface of the substrate is constant while maintaining the state where the suction portion of the head is magnetically attracted to the upper surface of the mask. Let For this reason, at least in the vicinity of the head, the mask can be supported by the head, and the upper surface of the mask can be adjusted to a position (height) set (planned) in advance to fill the holes with the fine balls. The microballs are filled in the holes of the mask as they pass through the head while being pushed by the head, and are mounted on the substrate through the mask. Therefore, according to this ball mounting apparatus, in a state where the height of the mask and the substrate is adjusted with reference to the upper surface of the mask, it is possible to mount a minute ball on the substrate through this mask.

  That is, according to this ball mounting apparatus, the mask is basically not supported by the substrate, and the height adjustment of the mask is not performed on the basis of the substrate. According to this ball mounting apparatus, the mask is magnetically attracted and supported by the head that moves so that the distance between the adsorption portion of the head and one surface of the substrate is constant. For this reason, the height of the mask is adjusted by the head (the positional relationship between the mask and the substrate is managed). Therefore, according to this ball mounting device, a minute ball is mounted on the substrate while the upper surface of the mask is maintained at a desired height by determining or controlling the distance between the suction portion of the head and one surface of the substrate. it can.

  Further, the suction between the mask and the suction portion of the head is due to magnetic force. Even a mask having a plurality of holes can be reliably sucked and supported by the head. Furthermore, even if the suction part of the head is moved relative to the upper surface of the mask in a state where the mask and the suction part of the head are attracted, the movement in the direction substantially perpendicular to the magnetic field lines is caused. Resistance (magnetic resistance) does not change.

  Therefore, according to this ball mounting apparatus, although the magnetic force is used, the minute ball can be moved on the mask with a small force by the head that can move in a direction hardly against the magnetic force. Then, the fine ball on the mask can be mounted on the substrate through this mask.

  Furthermore, when a micro ball is placed on the mask, the mask may be loosened or distorted to the substrate side due to the weight of the micro ball. According to this ball mounting device, the mask is pulled (lifted) by the head. Therefore, at least in the region where the micro ball is mounted (transferred) onto the substrate, the slack and distortion of the mask can be corrected.

  In this specification, a substrate indicates an object on which a minute ball is mounted, and includes a semiconductor wafer, a circuit board, and other workpieces. Some substrates have a metal layer, an insulating layer, or a plurality of layers including these formed on one surface of a substrate serving as a main body. Therefore, one surface of the substrate is not necessarily a flat surface. Furthermore, a flux or the like may be applied to one surface of the substrate.

  In the case of using the above-described substrate, in this ball mounting apparatus, one surface of the base body serving as the main body of the substrate, one surface of the substrate before applying the flux, the upper surface of the support base on which the substrate is mounted, etc. The head is moved so that the substantially flat surface corresponding to the reference surface of the substrate is the reference surface, and the distance between the head suction part and the reference surface of the substrate or the surface corresponding to the reference surface is constant. You may let them. That is, in this specification, moving the head so that the distance between the suction portion and one surface of the substrate is constant means that the head is horizontally aligned so that the distance between the suction portion and the substrate is substantially constant. Including moving in the direction.

  As an example of the head, one formed entirely or partly of a permanent magnet can be cited. Further, as the head, a head provided with means for generating a magnetic field may be used. Examples of means for generating a magnetic field include a coil for causing the entire head or a part thereof to function as an electromagnet.

  Further, as one of the conditions for filling the plurality of holes patterned in the mask without mistakes, a sufficiently large number of minute balls with respect to the number of holes (aperture density) is supplied onto the mask. Can be mentioned. However, the greater the number of microballs supplied on the mask, the more easily the mask is distorted by the weight of the microballs.

  Therefore, it is preferable that the head includes a hollow ball holding portion having an opening end on the side facing the mask. In the case of using such a head, it is preferable that the opening end includes a suction portion. According to this head, a group of minute balls can be held inside. Therefore, even if there are a relatively small number of microballs, the ball density of the portion through which the head passes (the portion into which the microballs are transferred) can be locally increased. For this reason, it is possible to efficiently fill the fine holes into the mask holes where the head passes. Note that the ball holding portion may be provided with a member such as a squeegee for sweeping a minute ball on the mask at or near the opening end.

  Further, the head can be rotated around an axis perpendicular to the mask, and this rotation can hold a group of minute balls on a part of the mask so that the minute balls do not escape. preferable. According to this head, a group of minute balls can be collected on a part of the mask. According to this head, the density of microballs in a part of the mask can be increased even with a relatively small number of microballs, as in the head including the hollow ball holding portion as described above. The fine balls can be efficiently filled into the mask holes where the head passes.

  These are preferred forms of heads that can enclose a portion of the mask by the adsorber and / or by movement of the adsorber and hold a population of microballs within the enclosed area. According to these heads, the micro-ball is held by the suction part and / or by the movement of the suction part, the area surrounding the part on the mask, that is, by the suction part of the head or by the movement of the suction part. Then, when an area moving on the mask by the movement of the head is a moving area, the mask around the moving area can be supported by the suction portion of the head. Therefore, by setting the level (height) of the mask around the moving area to a predetermined state, the level of the mask inside the moving area can be indirectly maintained accurately in the predetermined state. For this reason, the filling efficiency of microballs can be improved.

  As an example of this ball mounting device, a device capable of forming a magnetic circuit by magnetically coupling a mask and a head can be cited. In this case, if a magnetic induction closed circuit is formed by magnetic coupling between the mask and the head, leakage magnetic flux due to magnetic adsorption between the mask and the head can be reduced. An example of forming a magnetic circuit (closed circuit) with a mask and a head is to multipole magnetize the attracting portion. In this case, the magnetic pole may be formed of a permanent magnet or an electromagnet. An adsorption portion in which different polarities are alternately arranged is an example of multipolar magnetization.

  Further, according to this ball mounting apparatus, the distance between the upper surface of the mask and the substrate can be accurately controlled. Therefore, the mask may be supported with almost no gap between the mask and the substrate. It is also possible to support the mask in a state where a gap is provided between the mask and the substrate, and to arrange minute balls on the substrate. In this case, the head does not apply force to the substrate other than applying pressure to the substrate through the fine balls. Furthermore, ideally, the mask does not contact the substrate. Therefore, it is possible to eliminate the possibility that the surface (one surface) on the side where the minute balls of the substrate are mounted is damaged by pressure or the like.

  Furthermore, the microballs filled in the mask holes may float slightly with respect to the substrate or may have weak adhesion with the flux applied to the substrate. Therefore, it is preferable that the ball mounting apparatus further includes a press head for pressing the fine balls filled in the holes of the mask toward the substrate. By using such a press head, it is possible to reliably mount microballs on the substrate. In addition, since the press head presses after the fine holes are filled in the holes of the mask, the fine balls function as spacers and the mask is not pressed against the substrate.

  For example, the press head may be connected to the head and moved together with the head. When the head does not move only in one direction, the press head is preferably movable independently of the head. In this case, it is preferable that the ball mounting device further includes a press head moving device that moves the press head, and the head and the press head are independently moved. By doing this, no matter what movement trajectory the head follows, it follows the head along the mask (upper surface, surface, surface opposite to the substrate) after the head has passed. The press head can be controlled to move.

Another aspect of the present invention is a method for mounting a microball at a predetermined position on one surface of a substrate through a mask made of a magnetic body having a plurality of holes filled with microballs or a material containing the magnetic body. It is. This method includes the following steps.
(A1) A head for moving a minute ball on a mask, the head having a suction portion that moves while being attracted to the mask by a magnetic force, and a distance between the suction portion and one surface of the substrate Move so that becomes constant.

  According to this method, the fine ball on the mask is mounted on the substrate through the mask while the head is moved so that the distance between the adsorption portion of the head and one surface of the substrate is constant. can do.

Further, according to this method, since the mask is supported by the head, even if a mask having a simple configuration in which the surface facing the substrate is a flat surface is used, if necessary, a gap between the mask and the substrate is used. A gap can be provided. Therefore, it is preferable that this method further includes the following steps.
(A0) The mask is opposed to the substrate so that a gap is formed between the mask and the substrate.

  In this case, the suction portion and one surface of the substrate are provided such that a gap is provided between the mask-side surface of the mask and the mask-side surface of the substrate so that the microballs do not stray (less than the diameter of the microballs). More preferably, the interval between and is determined. By doing in this way, even if it uses the mask of a simple structure, it can suppress that flux etc. adhere to the surface at the side of a substrate of a mask.

Moreover, it is preferable that this method further includes the following steps.
(A2) The fine balls filled in the mask holes are pressed toward the substrate.

  By doing so, even when the balls are arranged on the substrate through the holes of the mask with a gap provided between the mask and the substrate, the microballs filled in the holes of the mask are removed. It can be securely mounted on a substrate.

  Yet another aspect of the present invention is a control method for a ball mounting apparatus for placing microballs at a predetermined position on one surface of a substrate through a mask. The ball mounting device is a head for moving a minute ball on a mask made of a magnetic material or a material containing a magnetic material, and having a plurality of holes filled with the minute ball. A head including a suction unit that moves in a sucked state; and a moving device that moves the head. And the said control method includes moving a head so that the space | interval of an adsorption | suction part and one surface of a board | substrate may become fixed with a moving apparatus.

  According to this control method, the fine ball on the mask can be mounted on the substrate via the mask while the mask is supported by the head.

  In addition, according to this control method, it is possible to keep the distance between the suction portion of the head and one surface of the substrate constant. That is, according to this control method, even if a mask having a simple configuration such that the surface facing the substrate is a flat surface is used, a gap is provided between the mask and the substrate, if necessary. Through this mask, a fine ball can be mounted on the substrate. In this control method, moving the head may include moving the head in the horizontal direction.

  In this case, the suction portion and one surface of the substrate are provided such that a gap is provided between the mask-side surface of the mask and the mask-side surface of the substrate so that the microballs do not stray (less than the diameter of the microballs). More preferably, the interval between and is determined. By doing in this way, even if it uses the mask of a simple structure, it can suppress that flux etc. adhere to the surface at the side of a substrate of a mask.

  Further, in this control method, it is preferable to use a ball mounting device that further includes a press head for pressing the fine balls filled in the holes of the mask toward the substrate and a press head moving device for moving the press head. . In this control method, the press head is preferably moved by the press head moving device so as to follow the movement of the head.

  By doing so, the head passes and fills the holes of the mask even when the balls are arranged on the substrate through the holes of the mask with a gap provided between the mask and the substrate. It is possible to reliably mount the fine ball on the substrate.

  A ball mounting apparatus according to an embodiment of the present invention is a mask made of a magnetic body having a plurality of holes filled with microballs or a material containing a magnetic body, and has a convex portion formed on a surface on the substrate side. Such an existing mask is used. In the ball mounting apparatus according to another embodiment of the present invention, the distance between the suction portion and one surface (upper surface) of the substrate is set so that the flat mask adheres to the substrate.

  In a ball mounting apparatus according to still another embodiment of the present invention, a gap is provided between the mask and the substrate for reasons such as not wanting the flux to adhere to the mask. In the ball mounting apparatus according to this embodiment, a gap (less than the diameter of the minute ball) between the mask side surface (lower surface) of the mask and the mask side surface (upper surface) of the substrate is sufficient. Is controlled to be provided. Further, the distance between the head suction portion and one surface (upper surface) of the substrate is controlled so that the minute balls hardly protrude from the upper surface of the mask.

  Further, in the ball mounting apparatus according to this embodiment, the height (position) of the upper surface of the mask is controlled by the suction portion of the head. For example, if the mask is distorted into a concave state and the distance between the mask and the substrate is too close, the mask is pulled by the suction portion of the head. If the mask is distorted convexly and the mask and the substrate are too far apart, the mask is pushed by the head. For this reason, the space | interval of a mask and a board | substrate is kept constant.

  Therefore, it is possible to prevent the upper portion of the fine ball filled in the mask hole from protruding from the upper surface of the mask. When the top of the microball protrudes from the top surface of the mask, it interferes with the squeegee that pushes the microball to move another microball on the mask, and the microball once filled in the hole of the mask May be scraped. If the distance between the mask and the substrate is too large, the microballs filled in the mask holes will enter between the mask and the substrate, resulting in a lost ball, but the distance between the mask and the substrate will remain constant. By doing so, generation of the lost ball can be prevented.

  In the ball mounting apparatus according to this embodiment, it is not always necessary to form convex portions or the like in a predetermined pattern on the substrate side surface (lower surface) of the mask. Therefore, using a flat mask including the lower surface, the lower surface of the mask can be kept away from the upper surface of the substrate. By using a flat mask including the lower surface, the lower surface can be easily cleaned even if a ball or flux is attached to the lower surface.

  A ball mounting apparatus using a mask in which no convex portion or the like is provided on the substrate side surface (lower surface) is one of the preferred embodiments of the present invention.

  A ball mounting apparatus according to a preferred embodiment will be described in detail below.

  FIG. 1 is a sectional view showing an example of a ball mounting device. FIG. 2 shows the shape of the lower end of the head provided in the ball mounting apparatus of FIG. 1 as viewed from below. FIG. 3 shows an enlarged view of the vicinity of the head of the ball mounting apparatus of FIG. FIG. 4 further shows the vicinity of the head and the vicinity of the press head of the ball mounting apparatus of FIG. In the following description, the direction parallel to the left and right of the paper surface of FIG. 1 is the X direction (left to right plus direction), the direction perpendicular to the paper surface is the Y direction (front to back plus direction), and the top and bottom of the paper surface. A direction parallel to (front-rear) will be described as a Z direction (front (lower) to rear (upper) + direction).

  A ball mounting device (microball mounter) 1 of this example is for mounting (mounting) a microball B at a predetermined position on an upper surface 100a of a substrate (workpiece) 100. The micro ball B is a conductive ball that functions as an electrode. As the microball B, for example, a solder ball having a diameter of 1 mm or less, specifically, a ball having a diameter of about 30 to 300 μm (a ball containing silver (Ag), copper (Cu), or the like, the main component of which is tin (Sn)). ), Metal balls made of gold or copper, or conductive balls in which a plastic ball is subjected to a treatment such as plating. In this example, a solder ball of about 90 μm is used as the minute ball B.

  The substrate 100 shown in this example is a planar circular semiconductor wafer of about 8 inches or 12 inches. Prior to the mounting of the solder balls B, the flux 102 is applied to the semiconductor wafer 100 on the region 101 to be an electrode. In this example, the flux 102 is applied on the region 101 to be an electrode of the wafer 100 so that the thickness is about 30 μm and the diameter is 90 μm.

  The ball mounting apparatus 1 mounts the conductive ball B on the upper surface 100a of the substrate 100 and the stage 10 that sucks the lower surface (back surface) 100b of the substrate 100 and supports the substrate 100 in a horizontal state by a method such as suction. The mask 20, the head 30 for moving the conductive ball B on the mask 20, the head moving device 40 for moving the head 30, and the conductive ball B filled in the hole of the mask 20 as a substrate. The press head 50 for pressing toward 100, the press head moving device 60 for moving the press head 50, and the control unit 70 for controlling the head moving device 40 and the press head moving device 60 are provided.

  The stage 10 is a platform that supports the substrate 100, and includes a disk-shaped support base 11 that is substantially the same as or slightly different in size from the substrate 100, and a frame 12 that is provided around the support base 11. The upper surface 11 a of the support base 11 is a surface that supports the lower surface 100 b of the substrate 100. The support surface 11 a is processed flat and serves as a reference surface that determines the height of the upper surface 100 a of the substrate 100. The support base 11 includes a plurality of suction holes 11b on the support surface 11a for supporting the substrate 100 by suction using air differential pressure. The support table 11 is configured such that an external vacuum generator (not shown) applies a negative pressure to the vicinity of the support surface 11a through these holes 11b, and the lower surface 100b of the substrate 100 is in close contact with the support surface 11a. By using such a support base 11, the flatness of the upper surface 100a of the substrate 100 can be improved.

  The mechanism for bringing the substrate 100 into close contact with the support surface 11a is not limited to adsorption, and may be an electrostatic chuck or the like. Further, the mechanism for bringing the substrate 100 into close contact with the support surface 11a can be configured by using a plurality of mechanisms in combination.

  An upper surface (upper end surface) 12a of the frame 12 is located around the support surface 11a of the support base 11 and has a substantially square outer shape. An upper end surface 12 a of the frame 12 is in contact with the mask 20 and supports the mask 20 in a region outside the substrate 100.

  The stage 10 has a function of moving the substrate 100 up and down apart from the mask 20 and further transporting the substrate 100 to a predetermined place. Accordingly, the substrate 100 is automatically transferred to the ball mounting apparatus 1 so that the conductive ball is mounted at a predetermined position, and then automatically transferred again to a predetermined place.

  The mask 20 can be formed of a magnetic material or a material containing a magnetic material, for example, a thin plate of ferritic stainless steel. Ferritic stainless steel is generally a magnetic material and is an example of a material suitable for forming the mask 20 of the ball mounting device 1 of this example because of its excellent durability. The mask can also be formed of other magnetic stainless steel, plastic containing magnetic material, or the like. A mask made of a non-conductive and magnetic material is suitable for preventing or reducing eddy currents that may occur when the head is moved while being in close contact with the mask by magnetic force.

  The mask 20 is formed in a flat plate shape having a flat upper surface 20a and a lower surface 20b. The mask 20 is not limited to a single layer structure, and may have a multilayer structure. For example, by coating the upper surface 20a of the mask 20 in contact with the head 30 with a low-friction thin film material such as a fluorine-containing resin, the head 30 can be moved even when the head 30 is attracted to the mask 20 by a magnetic force. It can be moved well.

  The mask 20 is provided with a plurality of holes 21 filled with the conductive balls B with a diameter almost penetrating the conductive balls B in order to dispose the conductive balls B at predetermined positions on the substrate 100. . The plurality of holes 21 are often formed with a repetitive design (predetermined pattern), and are also referred to as mask holes, openings, openings, pattern holes, and the like. These holes 21 may be collectively referred to as an opening pattern. An example of the mask 20 for mounting the solder balls B having a diameter of about 90 μm on the wafer 100 has a mask thickness of about 50 μm and a diameter of the hole 21 of about 100 μm. The mask 20 is fixed to the mask frame 22 in a state where a certain amount of tension is applied.

  The head 30 for supplying the conductive ball B onto the upper surface 20 a of the mask 20 includes a hollow ball holding portion 32 having an open end 31 on the lower side facing the mask 20. The ball holding part 32 is made of a metal whose main component is a magnetic material such as iron, and is formed in a bottomed cylindrical shape whose upper side is closed. Like the mask 20, ferritic stainless steel is an example of a material suitable for forming the ball holding portion 32.

  A coil 33 for generating a magnetic field is provided on the outer periphery of the ball holding portion 32. The coil 33 is formed by winding an insulated wire around the outer periphery of the ball holding portion 32. In the head 30, when a current is passed through the coil 33, a magnetic field using the ball holding portion 32 as an electromagnet is generated, and the tip 31 of the ball holding portion 32 is magnetized to the S or N pole. Therefore, the mask 20 that is a magnetic body can be adsorbed to the open end (tip surface) 31 of the ball holding portion 32. That is, in the head 30, the opening end 31 of the ball holding portion 32 becomes the suction portion 34. The open end 31 is flat. In this ball mounting apparatus 1, the suction portion 34 having a flat surface in contact with the mask 20 is attracted to the mask 20 by magnetic force, and in this state, the head 30 is moved along the upper surface 20 a of the mask 20 by the head moving device 40. It can be moved across the upper surface 20a.

  The head moving device 40 is a device for moving the ball holding portion 32 of the head 30 to an arbitrary position on the upper surface 20a of the mask 20 along the XY plane (horizontal plane). At that time, the head moving device 40 controls the position (height) of the head 30 so that the distance S between the suction unit 34 of the holding unit 32 and the upper surface 100a of the substrate 100 is constant. Furthermore, the head moving device 40 also has a function of vibrating the ball holding portion 32 with a small width along the XY plane (horizontal plane).

  The head moving device 40 includes a first shaft 41 extending horizontally in the X direction, a second shaft 42 for moving the first shaft 41 horizontally in the Y direction, and a first shaft 41. And a carriage 45 that moves in the X direction. Various mechanisms can be employed to drive the carriage 45 and the shafts 41 and 42. Examples include a drive mechanism using a timing belt, a combination of spiral leads and pins provided on a shaft, and a drive mechanism using a ball screw. The carriage 45 includes a drive mechanism 43 that supports the head 30 and incorporates a motor for vibrating the ball holding portion 32 of the head 30 along the XY plane.

  The head 30 moves horizontally in any direction by the first and second shafts 41 and 42. Therefore, the head 30 can move in any direction on the XY plane so that the distance S between the suction portion 34 and the upper surface 100a of the substrate 100 is constant, and can be set at any position on the upper surface 20a of the mask 20. . The head moving device 40 (the operation of the head 30) is controlled by the control unit 70. The coil 33 for generating a magnetic field can be controlled in the same manner as the focus coil or the voice coil, and an appropriate surface serving as a reference with respect to the height of the suction portion 34 or the upper surface 100a of the substrate 100, for example, the support surface 11a of the support base. You may actively control the distance. The accuracy of the distance S between the suction portion 34 and the upper surface 100a of the substrate 100 can be further improved.

  In FIG. 2, as an example of the vibration direction of the head 30, a direction A <b> 1 along the X axis and a direction A <b> 2 along the Y axis are illustrated with arrows, but the vibration direction of the head 30 is XY. The direction is not limited to the direction A1 along the X axis and the direction A2 along the Y axis as long as the direction is along the plane. As the vibration direction of the head 30, any one direction on the XY plane can be selected.

  In addition, a ball replenishing device 36 for replenishing the conductive ball B to the inside I of the ball holding portion 32 is mounted on the carriage 45. The ball supply device 36 and the ball holding portion 32 are connected by a supply pipe 35 extending in the Z direction. The amount of balls supplied from the ball supply device 36 is controlled by the control unit 70.

  The head 30 is preferably moved so as to cover the entire mask 20 or at least the entire region into which the ball is transferred without omission. At this time, the head 30 may be moved so that a part of the trajectory overlaps. By doing in this way, the incidence rate of filling mistakes of the conductive balls B with respect to the substrate 100 can be kept low.

  As the trajectory of the head 30, an arbitrary trajectory such as a spiral or spiral trajectory, a zigzag, a sine curve, or a meandering trajectory can be selected. The spiral or spiral trajectory is suitable when the substrate 100 is circular, the mask 20 is circular, or the region filled with the conductive ball B is circular. When selecting a spiral trajectory, the head 30 is moved from the outside of the region where the hole 21 is provided to the vicinity of the center of the mask 20 and then spirally moved from the center of the mask 20 toward the periphery. By doing so, unfilling of the conductive balls B in the central portion of the mask 20 and in the vicinity thereof can be reduced.

  The conductive ball B held by the head 30 falls (fills) into the hole 21 of the mask 20 in the region surrounded by the open end 31 of the ball holding portion 32 by its own weight. In particular, when the portion where the conductive ball B exists in one layer (the portion where the conductive ball B is not laminated) passes through the hole 21 of the mask 20, the conductive ball B fills the hole 21 most efficiently. Is done.

  In this mounting apparatus 1, the ball holder 32 is linearly or circularly or elliptically arranged in an appropriate direction along the XY plane in a state where the suction portion 34 is attracted to the upper surface 100 a of the substrate 100 by a magnetic force. The head 30 is moved to an arbitrary position on the upper surface 20a of the mask 20 while vibrating (swinging) as depicted. For this reason, in a region surrounded by the opening end 31 of the ball holding portion 32, that is, a region (moving region) in which a portion on the mask 20 is surrounded by the suction portion 34, a portion of the region on the mask 20 is included. The conductive balls B are unevenly distributed, and there are regions where the conductive balls B are present and regions where the conductive balls B are not present. Furthermore, a portion where the conductive ball B is formed in one layer is formed at a boundary portion between the region where the conductive ball B exists and the region where the conductive ball B does not exist. Therefore, the conductive ball B can be satisfactorily filled into the hole 21 of the mask 20 by vibrating the head 30 along the XY plane.

  The press head 50 moves the upper surface 20 a of the mask 20 by the press head moving device 60 so as to follow the movement of the filling head 30. The press head 50 is for pressing the conductive balls B filled in the holes 21 of the mask 20 toward the substrate 100. The press head 50 includes a press unit 51 protruding downward from the carriage 65 of the moving device 60, a coil spring 52 that urges the press unit 51 downward (mask 20 side), and an upper side of the coil spring 52 (mask 20 side). And a support member 53 that supports the carriage 65 on the opposite side.

  The press head moving device 60 is a device for moving the press head 50 along the XY plane. The press head moving device 60 includes a third shaft 61 extending horizontally in the X direction, a fourth shaft 62 for moving the third shaft 61 horizontally in the Y direction, and a third shaft 61. And a carriage 65 on which the press head 50 is mounted. As the mechanism for driving the carriage 65 and the shafts 61 and 62, the same mechanism as that of the head moving device 40 can be adopted. The press head 50 moves independently of the filling head 30 by the third and fourth shafts 61 and 62. Therefore, the press head 50 can be moved in any direction on the XY plane suitable for pressing the conductive ball B mounted on the substrate 100, and can be set at any position. The press head moving device 60 is controlled by the control unit 70.

  The press head 50 may be installed so as to be connected to the filling head 30 and moved together with the head 30. In this case, the press head moving device 60 can be omitted, but it is desirable that the height control of the filling head 30 is not difficult due to the reaction force of the press head 50.

  The control unit 70 has a first function for moving the head 30 horizontally by the head moving device 40 and a second function for moving the press head 50 so as to follow the movement of the head 30 by the press head moving device 60. It has a function. In the present example, the first function includes a function of moving the head 30 so that the distance S between the suction portion 34 and the upper surface 100a of the substrate 100 is constant.

  Hereinafter, a method of mounting the conductive ball B at a predetermined position on the upper surface 100a of the substrate 100 using the ball mounting apparatus 1 will be described. FIG. 5 shows a flowchart for explaining an example of the control method of the ball mounting apparatus.

  First, in step 201, the substrate 100 is set on the support base 11 and the mask 20 is set on the frame 12. At this time, the mask 20 is opposed to the substrate 100 so that a substantially equal gap S1 is formed as a whole between the mask 20 and the substrate 100 (the lower surface 20b of the mask 20 and the surface of the flux 102). In the region where the conductive ball B is filled, the gap between the mask 20 and the substrate 100 is controlled to a value suitable for filling with high accuracy by the suction end 31 of the head 30. In addition, since the conductive ball B basically stays in the region surrounded by the holding part 32, the accuracy of the height of the mask 20 when the mask 20 is initially set is not so required. However, it is desirable to set the gap S1 so that the conductive ball B does not get lost (less than the diameter of the conductive ball B).

  Further, the ball mounting apparatus 1 of this example includes a press head 50 that pressurizes the conductive ball B. For this reason, the mask 20 is set so that the position of the upper surface 20a has a plus tolerance upward, and not only the conductive ball B but also the mask 20 is pressed by the press head 50. For example, the mask 20 is set such that the position of the upper surface 20a is higher than the top level of the position where the conductive ball B is to be mounted on the upper surface 100a of the substrate 100 by a height d. Since the gap S1 between the mask 20 and the substrate surface 100a can be set wide, it is possible to prevent the mask 20 from coming into contact with the substrate surface 100a even if the mask 20 is slightly bent.

  The head 30 is moved on the mask 20. In step 202, an electric current is supplied to the coil 33 to generate a magnetic field, thereby attracting the suction portion 34 of the head 30 and the mask 20. Thereafter, the conductive ball B is supplied to the inside I of the ball holding portion 32 of the head 30. The head 30 and the mask 20 are magnetically attracted. For this reason, the conductive ball B once held in the region surrounded by the ball holding portion 32 and the mask 20 does not leak from this region. Therefore, the conductive ball B is held in a desired region, and the range in which the conductive ball B moves is controlled by the head 30. Further, since the mask 20 is supported at a constant height by the head 30, the flatness (surface accuracy) of the mask 20 at least in the vicinity of the head 30 is improved.

  In step 203, the head 30 is vibrated by the head moving device 40 so that the distance S between the suction portion 34 and the upper surface 100 a of the substrate 100 is constant, and a part of the trajectory of the head 30 overlaps ( Move horizontally while swinging. As a result, the conductive ball B on the mask 20 moves while being pressed by the inner wall surface F of the ball holding portion 32, and a part of the conductive ball B is filled (transferred) into the mask hole 21 along the trajectory of the head 30. ) And are arranged at predetermined positions on the substrate 100. The remaining conductive balls B move on the mask 20 while being held by the head 30, and are successively filled (swinged) into the holes 21 of the mask.

  At this time, if S between the mask 20 and the substrate 100 is separated from a desired value, the head 30 is on the mask, so the head 30 pushes the mask 20. If S between the mask 20 and the substrate 100 is closer than a desired value, the head 30 attracts the mask 20 by magnetic force, so the head 30 pulls the mask 20. Therefore, at least in the region where the minute balls B are on the mask 20 and are mounted (transferred) onto the substrate 100, the height of the mask 20 is controlled to a desired value, and the head 30 is further loosened. And distortion is corrected. For this reason, the conductive balls B are satisfactorily filled in the holes 21 formed in the mask 20, and are arranged on the upper surface 100 a of the substrate 100 through the mask 20.

  In step 204, the press head 50 is moved independently of the head 30 so as to follow the movement of the head 30. The start of step 204 may be almost the same as the start of step 203 even after a while after step 203 is started.

  In this example, the mask 20 is positioned so that the position of the upper surface 20a of the mask 20 is higher than the top level of the position where the conductive ball B is to be mounted on the upper surface 100a of the substrate 100 by a height d. Is set. Therefore, as shown in FIG. 4, when the conductive ball B is pressed by the press head 50, the mask 20 is also pressed together. Accordingly, only the region of the upper surface 20a of the mask 20 that is pressed by the press head 50 is lowered by the height d from the set position. However, in the region where the press head 50 presses the mask 20, the conductive ball B is transferred, so that the conductive ball B becomes a spacer. Therefore, there is little possibility that the mask 20 contacts the surface 100a of the substrate.

  The conductive ball B filled in the hole 21 of the mask 20 is pressed toward the substrate 100 with an appropriate force by the press portion 51 urged by the coil spring 52. Due to the operation of the press head 50, the conductive ball B is satisfactorily mounted on the substrate 100. For example, although the conductive ball B is filled in the hole 21 of the mask for some reason, the conductive ball B that is not in contact with the substrate surface 100a is surely in contact with the substrate surface 100a. Further, when the flux is applied to the surface 100a of the substrate, the conductive ball B can be stabilized on the surface 100a of the substrate by increasing the contact area between the conductive ball B and the flux.

  As described above, according to this ball mounting apparatus 1, the distance S between the mask 20 and the substrate 100 is kept constant. Then, while maintaining the state in which the attracting portion 34 of the head 30 is magnetically attracted to the upper surface 20a of the mask 20, the head 30 is set so that the interval S between the attracting portion 34 and the upper surface 100a of the substrate 100 is constant. Move. Therefore, the conductive ball B can be mounted on the substrate 100 through the mask 20 in a state where the alignment of the mask 20 and the substrate 100 is performed with reference to the upper surface 20a of the mask 20.

  Furthermore, according to this ball mounting apparatus 1, a mask 20 having a simple configuration such as a flat mask 20 can be applied. Even if the lower surface 20 b is a flat mask 20, the gap 102 is held so as to open between the substrate 100 and the flux 102 is unlikely to adhere to the lower surface 20 b. In addition, a mask with a simple structure in which the surface facing the substrate 100 is a flat surface is low in manufacturing cost, easy to ensure accuracy reliability, and easy to clean. Therefore, according to this ball mounting apparatus 1, mounting errors of the conductive balls B onto the substrate 100 can be reduced.

  Adsorption between the mask 20 and the adsorption portion 34 of the head 30 is based on magnetic force. For this reason, even if the suction portion 34 of the head 30 is moved in a state where the mask 20 and the suction portion 34 of the head 30 are attracted, the magnetic resistance between the mask 20 and the head 30 does not change. Therefore, according to this ball mounting apparatus 1, the resistance when moving the conductive ball B on the mask 20 by the head 30 is small, and the head 30 can be smoothly moved by the head moving apparatus 40 with a small force. For this reason, the head moving device 40 can be made compact. Further, the state in which the mask 20 and the head 30 are magnetically attracted during movement can be maintained. For this reason, the conductive ball B held in the region surrounded by the ball holding portion 32 and the mask 20 does not leak out from this region and become a lost ball on the mask 20.

  Hereinafter, another example of the ball mounting apparatus is shown. FIG. 6 is a sectional view showing another example of the ball mounting apparatus. FIG. 7 shows the shape of the lower end of the head. FIG. 8 is an enlarged view of the vicinity of the head. FIG. 9 shows the relationship between the head and the press head.

  The ball mounting apparatus 1 includes a stage 10 that moves the substrate 100 that has been sucked under reduced pressure, a mask 20 that fills the substrate 100 with the ball B (mounts, transfers, or naturally drops), and the ball B on the mask 20. Head 30 to be moved, head moving device 40 to move head 30, press head 50 that presses ball B filled in hole 21 of mask 20 into flux 102, and press head moving device to move press head 50 60, a ball supply device 36 for supplying the ball B to the head 30, and a control unit 70.

  The stage 10 includes a substrate support 11 and a frame 12. Further, as X, Y, Z, and θ direction drive devices, although not shown, a commonly used X axis table, Y axis table, Z axis table, and θ table are provided. The substrate 100 moves between the substrate loader / unloader (not shown), the substrate correction device (not shown), the flux printing device (not shown), and the ball mounting device 1 by these driving devices. Furthermore, the height adjustment of the substrate 100 and the adjustment of the angle deviation between the substrate 100 and the mask 20 are also performed by these driving devices.

  The support base 11 includes a plurality of suction holes 11b for suctioning the substrate 100 under reduced pressure. The support base 11 is provided with push pins (not shown) that push the substrate 100 upward. Note that the mechanism for bringing the substrate 100 into close contact with the support surface 11a is not limited to the vacuum suction, and an electrostatic chuck or a combination thereof may be used.

  The frame 12 includes a dedicated Z-axis drive device (not shown). And it moves up and down independently of the support stand 11, and can set the difference of the height of the support stand 11 and the flame | frame 12 arbitrarily. With this mechanism, it is possible to deal with substrates having different thicknesses and substrates having warpage.

  The mask 20 is fixed to the mask frame 22 in a state where tension is applied. The mask frame 22 is fixed to a fixing part (not shown) such as a frame of the ball mounting apparatus 1.

  This mask 20 has a ball B having a diameter of 90 μm mounted on the wafer 100 and is a foil having a mask thickness of 50 μm, and a hole 21 having a diameter of 100 μm is formed at a position corresponding to the electrode 101. The opening end of the hole 21 may be chamfered.

  The head 30 includes a hollow ball holding portion 32 having an open end 31 at the lower portion. The ball holding part has a magnetism generating part 80 and a connecting part 82. The magnetism generator 80 includes an upper yoke 80a, a lower yoke 80b, a spacer 81, and a coil 33, and is fixed to the connecting portion 82 with screws or the like. The upper yoke and the lower yoke are configured separately to mount the coil 33 in the magnetism generator 80. The upper yoke 80a is a donut-shaped disk, and the lower yoke 80b is divided into an inner yoke and an outer yoke. These yokes are made of a magnetic material having a low residual magnetic flux density and high permeability (for example, pure iron, mild steel, low carbon steel, permalloy, soft ferrite). If a large residual magnetic flux remains, the head and the mask continue to be magnetically attracted, so that it is necessary to devise such as removing the head at the periphery of the mask when separating the head from the mask.

  The spacer 81 has a cylindrical shape, the width is the same as the mask thickness, and the height is ½ of the mask thickness. The material is a paramagnetic material, made of a copper alloy or resin, and may be a void. The width of the spacer 81 is made thin so that the mask can be magnetically attracted locally.

  The coil 33 is an annular coil in which an insulated copper wire is turned 20 times, and two power wires (not shown) extend outside the magnetism generator. The coil 33 is made by winding an insulating copper wire around the coil frame 83. The coil frame 83 is fitted into the yoke 84a in the lower yoke 80b. Further, without using the coil frame 83, an insulating copper wire may be directly wound around the inner yoke 84a. The insulated copper wire is fixed with an adhesive and does not move due to vibration or the like. The current flowing through the coil 33 is controlled by the controller 70 and can be adjusted while observing the transfer state of the ball B.

  Further, the coil 33 for generating a magnetic field can be controlled in the same manner as the focus coil or the voice coil, and an appropriate surface serving as a reference with respect to the height of the suction portion 34 or the upper surface 100a of the substrate, for example, a support surface of a support base. The distance to 11a can be positively controlled. The accuracy of the distance S between the suction portion 34 and the upper surface 100a of the substrate 100 can be further improved.

  The magnetism generator 80 is assembled by adding a spacer 81 in a state where the coil 33 is incorporated, and is connected to the connecting portion 82. The lines of magnetic force generated by the current flowing through the coil 33 are indicated by arrows in FIG. The direction of the lines of magnetic force is reversed depending on the direction of the current flowing through the coil.

  The magnetic circuit will be described below. The magnetic circuit is based on an annular continuous magnetic head. The lines of magnetic force generated from the coil 33 constitute a closed circuit that passes through the upper yoke 80a, the lower yoke 80b, the spacer 81, and a part of the mask 20. Since the upper and lower yokes 80a and 80b are designed so that the magnetic flux is not saturated, the magnetic flux hardly leaks from the upper and lower yokes 80a and 80b to the space. However, since the portion where the spacer 81 is arranged has high magnetic resistance, the magnetic flux leaks in an annular shape. The leaked annular magnetic flux passes through the mask 20 and returns to the lower yoke 80b. Further, in the region where the lower yoke 80b and the mask 20 are in contact, a part of the magnetic flux leaks from the lower yoke 80b to the mask 20, and returns to the lower yoke 80b again through the mask 20. The amount of magnetic flux passing through the mask 20 determines the attractive force between the head 30 and the mask 20, and a value obtained by differentiating the magnetic flux amount by distance corresponds to the magnetic attractive force.

  Further, when the magnetic flux generated by the magnetism generating unit 80 reaches the substrate 100, the mounted semiconductor element may be deteriorated or damaged. In this example, the thickness (height) and width of the spacer 81 are set so that the leakage magnetic flux does not adversely affect the substrate. For example, when the spacer width is the same as the mask thickness, a gap comparable to the mask thickness is provided between the mask 20 and the substrate 100, so that the influence of the leakage magnetic flux on the substrate 100 is small.

  The ball replenishing device 36 is mounted on the carriage 45, moves together with the head 30, and replenishes the ball B stored therein to the inside I of the ball holding unit 32. The ball replenishing device 36 and the ball holding portion 32 are communicated by a supply pipe 35 extending in the Z direction. The amount of balls replenished from the ball replenishing device 36 is controlled by a control unit 70 that stores in advance setting data relating to replenishment. A sensor such as an image camera or a capacitance sensor may be provided in order to control the replenishment of the ball that has decreased due to the filling of the ball.

  Since the head 30 is connected to the X-axis table 41 via the carriage 45, the X-Y plane can be moved to an arbitrary position by the X-axis table 41 and the Y-axis table 42. Furthermore, the distance between the head 30 and the mask 20 can be arbitrarily set or controlled by a Z-axis table (not shown). Thus, the head 30 can be arbitrarily moved horizontally and vertically. Further, the head moving device 40 may have a function of vibrating the ball holding unit 32 with a small width along the XY plane. Furthermore, the carriage 45 may include a drive mechanism 43 that supports the head 30 and incorporates a motor for vibrating the ball holding portion 32 of the head 30 along the XY plane. In FIG. 7, as an example of the vibration direction of the head 30, the direction A <b> 1 along the X axis and the direction A <b> 2 along the Y axis are illustrated with arrows, but the vibration direction of the head 30 is represented by the direction A <b> 1 or The direction A2 is not limited, and an arbitrary direction can be selected.

  As shown in FIG. 9, the press head 50 includes a press unit 51 disposed below the carriage 65, a spring 52 that urges the press unit 51, a support unit 53 that supports the spring 52 on the carriage 65, A Z-axis drive device (not shown) is provided.

  If the ball B filled in the hole 21 is not pressed by the head 30, the ball B is only on the flux 102, and since the adhesive force with the flux 102 is small, it is easy to move. It is necessary to sufficiently push the ball B into the flux 102 with the press head 50. However, if the ball B is pressed too strongly, the ball B is pressed strongly against the electrode 101, causing problems such as deformation and displacement of the ball. When the surface of the electrode 101 is flat and the ball B is pushed downward at the center of the press head 50, the ball B does not move to the left or right, but when the surface of the electrode 101 is not flat, the ball B is separated from the center of the ball B. When the press head 50 pushes the portion, the ball B moves to the left and right.

  The pressing force of the press head 50 is a value obtained by adding the urging force of the spring 52, the weight of the press unit 51, and the force from the Z-axis driving device, and therefore the urging force of the spring 52 is large and faces downward. If so, the ball B may be damaged depending on the size, material and quantity of the ball B. In that case, it is preferable to set the weight of the press portion 51 and the spring constant so that the biasing force of the spring 52 is directed upward and the biasing force of the spring 52 and the weight of the press portion 51 are counterbalanced. More preferably, the press part 51 is attached to a pneumatic cylinder (not shown). When the spring constant is set large so that the pressing portion 51 is lifted upward by the biasing force of the spring 52, and the upward biasing force of the spring 52 and the force of the pneumatic cylinder are balanced, the press head 50 is moved to the Z-axis drive device. The counter balance can be maintained even if it is moved by. With this structure, even if the Z-axis driving device is lowered and the press head 50 is pressed against the ball B, the generated stress can be reduced. In this case, the ball B only enters the flux 102, and the deformation and movement of the ball B do not occur.

  The moving device 60 of the press head 50 includes an X-axis table 61, a Y-axis table 62, and a Z-axis table (not shown). Furthermore, it is good to provide the pneumatic cylinder (not shown) which presses the press part 51 below independently.

  The press head 50 can move independently of the filling head 30. The influence that the mask 20 is pushed down by the press head 50 does not reach the area surrounded by the opening end 31 (hereinafter referred to as a moving area). FIG. 9 shows the press head 50 in the vicinity of the ball filling head 30. During the ball filling, the press head 50 is retracted to the retracted position and lowered to press the ball B after the ball filling is completed. You may do it. In this case, the tip of the press head 50 can have a large pressing area such as a plate shape. The press head 50 may be installed so as to be connected to the ball filling head 30 and moved together with the head 30. In this case, the press head moving device 60 can be omitted, but it is desirable that the height control of the filling head 30 is not difficult due to the reaction force of the press head 50. Further, the control unit 70 has a function of moving the press head 50 so as to follow the movement of the head 30.

  Furthermore, in the ball mounting apparatus according to another embodiment, there is a gap between the mask 20 and the substrate 100 because, for example, it is not desired to attach flux to the mask 20 in which convex portions are formed in a predetermined pattern on the lower surface 20b of the mask 20. Is provided. In the ball mounting apparatus according to this embodiment, control is performed such that a gap is provided between the mask 20 and the substrate 100 so that the ball B does not stray. Further, the distance S between the suction portion 34 of the head 30 and the substrate 100 is controlled so that the minute balls B hardly protrude from the mask 20.

  In the ball mounting apparatus according to this embodiment, the height of the mask 20 is controlled by the suction portion 34 of the head 30. For example, if the mask 20 is distorted in a recessed state and S1 is too close between the mask 20 and the substrate 100, the mask 20 is pulled by the suction portion 34 of the head 100. If the mask 20 is distorted into a convex shape and S1 is too far between the mask 20 and the substrate 100, the mask 20 is pushed by the head 100. For this reason, the distance S1 between the mask 20 and the substrate 100 is kept constant.

  Therefore, the upper part of the ball B filled in the hole 21 of the mask 20 can be prevented from protruding from the mask 20. By preventing the upper part of the ball B from protruding from the upper surface 20a of the mask 20, a member that pushes the minute ball B to move another ball B on the mask 20, for example, an open end (front end) ) The interference between the ball 31 and the ball B is suppressed, and the possibility that the minute ball B once filled in the hole 21 of the mask 20 is scraped off can be reduced. If S1 is too far between the mask 20 and the substrate 100, the ball B filled in the hole 21 of the mask 20 enters the S1 between the mask 20 and the substrate 100 and becomes a lost ball. By keeping S1 between the substrate 100 and the substrate 100 constant, generation of the lost ball can be prevented.

  Hereinafter, a method of mounting the ball B at a predetermined position of the substrate 100 using the ball mounting apparatus 1 will be described. The ball mounting method using this ball mounting apparatus 1 is basically the same as that of the above-described embodiment. Therefore, with reference to FIG. 5, the main process regarding the control method of this ball mounting apparatus will be described.

  In this example, the substrate 100 is a nominal 8 inch or 12 inch semiconductor wafer. In the substrate, the flux 102 is applied to the electrode 101. In this example, the flux has a thickness of 30 μm and a diameter of 90 μm. As the ball B, a solder ball having a diameter of 90 μm was used. The ball diameter is preferably 20 to 1,000 μm, more preferably 30 to 300 μm. The substrate 100 may be a rectangular mounting substrate.

  In the present embodiment, the ball B refers to a conductive ball such as a lead-free solder ball, a lead-containing solder ball, a gold ball, or a copper ball. Further, a resin ball, a ceramic ball or the like formed with a conductive film may be used. The material of the mask 20 is made of a magnetic material, and examples thereof include ferritic stainless steel and electroformed nickel. The structure of the mask 20 may be a laminate of magnetic materials, a laminate of magnetic materials and nonmagnetic materials, or a mixed material of magnetic materials and nonmagnetic materials. For example, a structure in which the mask surface 20a in contact with the head 30 is coated with a fluorine-containing resin that is a low friction material is preferable because friction between the mask 20 and the head 30 is reduced. Further, a structure in which wear-resistant materials are laminated or coated is preferable because generation of fine dust can be prevented. Moreover, since the thickness of the mask 20 will become 20-30 micrometers thin when the ball | bowl to mount becomes 50 micrometers or less, lamination | stacking of a thin plate with a high mechanical strength and a magnetic thin film is also preferable. When manufacturing masks with stainless steel, machining, electrical discharge machining, and etching are used. In electroforming, the cross-sectional shape of the hole can be produced arbitrarily. Furthermore, the mask 20 may be reinforced by providing a horizontal beam or a vertical beam on the lower surface 20b of the mask 20 in a region where the flux 102 is difficult to adhere.

  Similar to the mask 20, the opening end 31 of the head 30 may be compounded with a material having a low coefficient of friction or a material having wear resistance.

  First, in step 201, after the substrate 100 is vacuum-sucked to the support base 11 at a location away from the ball mounting position, the substrate 100 is moved to the ball mounting position. In the meantime, a process of correcting the warp of the substrate 100 or printing the flux may be provided. Next, the coordinates of the position mark (not shown) of the substrate 100 and the position mark (not shown) of the lower surface 20 b of the mask 20 are measured, and the substrate 100 placed on the support base 11 is aligned with the mask 20. Further, the frame 12 is moved relative to the support base 11 so that the gap between the mask 20 and the substrate 100 becomes 110 μm. The height of the frame 12 may be moved to a predetermined height in advance prior to this step 201. The distance S1 between the mask 20 and the substrate 100 may be set so that the ball B mounted on the substrate 100 is pushed into the flux 102 by being pushed by the opening end 31 of the head 30 (about 10 μm). The interval S1 between the mask 20 and the substrate 100 is a height at which the flux does not adhere to the mask 20 and a height at which the ball B does not enter between the mask 20 and the substrate 100. Since the ball B has a spherical shape, when the center of the ball B is lower than the lower surface 20 b of the mask 20, the ball B easily enters between the mask 20 and the substrate 100. Therefore, the gap S1 between the mask 20 and the substrate 100 is preferably less than the ball radius. Although depending on the substrate, the thickness of the electrode 101 is usually so thin that it can be ignored as 1 μm or less.

  In the region where the ball B is filled, the gap S1 between the mask 20 and the substrate 100 is controlled to a value suitable for filling by the suction end 31 of the head 30 with high accuracy. Further, since the ball B basically stays in the area surrounded by the ball holding portion 32, there may be a case where the accuracy of the height of the mask 20 is not so required when the mask 20 is initially set. However, the gap S1 is set so that the ball B does not get lost (less than the diameter of the ball B).

  Further, the ball mounting apparatus 1 of this example includes a press head 50 that pressurizes the ball B. For this reason, the mask 20 may be set so that the position of the upper surface 20a has a plus tolerance upward, and not only the ball B but also the mask 20 may be pressed by the press head 50. For example, the mask 20 may be set such that the position of the upper surface 20a is higher than the top level of the position where the ball B is to be mounted on the upper surface 100a of the substrate 100 by a height d. Since the gap S1 between the lower surface 20b of the mask 20 and the surface 100a of the substrate can be set wide, it is possible to prevent the mask 20 from coming into contact with the surface 100a of the substrate 100 even if the mask 20 is somewhat bent.

  In step 202, the head 30 is lowered so that the lower end of the head 30 evacuated to the outer periphery of the mask 20 is at a height in contact with the mask 20. The height of the head 30 is measured using a level gauge, but may be a position sensor. Next, a direct current is applied to the coil 33 to magnetically attract the head 30 and the mask 20 so that the ball B does not leak from between the head 30 and the mask 20. Thereafter, the initial ball amount is supplied from the ball supply device 36 to the in-head I. Starting with the initial ball amount, the ball amount held in the ball holding portion 32 includes an area where the ball B exists in the moving area and an area where the ball B does not exist while the head 30 moves along a predetermined locus. It is set to be possible.

  Although the head 30 can move in the Z direction but is held by the driving device 40 with a large holding force, if there is a gap between the head 30 and the mask 20, the head 30 does not move and the mask 30 does not move. 20 is attracted to the head 30. Since the mask 20 is supported at a constant height by the head 30, the flatness (surface accuracy) of the mask 20 at least in the vicinity of the head 30 is improved. Further, the suction force between the head 30 and the mask 20 may be set to such an extent that the ball B that has entered I between the head 30 and the mask 20 can be delivered from the opening end 31 of the head 30 without damaging it. .

  In step 203, the head 30 is moved from the peripheral portion of the mask 20 to a ball filling start position (for example, the central portion of the mask). Subsequently, the interval S between the suction unit 34 and the substrate 100 is set to a predetermined distance, and the head 30 is moved in the horizontal direction along a preset locus. As the trajectory of the head 30, an arbitrary trajectory such as a spiral or spiral trajectory, a zigzag, a sine curve, or a meandering trajectory can be selected. A spiral or spiral trajectory is suitable when the area filled with the ball is circular. When selecting a spiral trajectory, the head 30 is moved from the outside of the region where the hole 21 is provided to the vicinity of the center of the mask 20 and then spirally moved from the center of the mask 20 toward the periphery. By doing so, it is possible to reduce unfilled balls in the central portion of the mask 20 and in the vicinity thereof.

  Balls corresponding to the amount of balls reduced by filling are intermittently supplied to the head 30 from the ball supply device 36. The ball B held by the head 30 falls (fills) into the hole 21 of the mask 20 in the moving area by its own weight. In particular, when the portion where the ball B exists in one layer passes through the hole 21 of the mask, the ball is filled into the hole 21 most efficiently.

  The trajectory of the head 30 is such that the moving area overlaps by 50%. The overlapping ratio of moving areas is preferably 10 to 90%. If it is less than 10%, the number of holes 21 that are not filled with balls increases, and if it is 90% or more, it takes too much filling time. The overlapping rate is more preferably 20 to 80%. As the head 30 moves, the ball B moves while being pushed by the inner wall surface F of the ball holding portion 32, and a part of the ball B fills the hole 21 of the mask 20 along the trajectory of the head 30. It is arranged at the position. The remaining balls B move on the mask 20 while being held by the head 30 and are successively filled in the holes 21 of the mask 20. It should be noted that the movement area overlapping when the head 30 moves along a predetermined trajectory corresponds to the number of times the movement area passes over the hole 21 of the mask 20. For example, a trajectory where the moving area overlaps by 0% is a trajectory where the moving area passes once through all of the mask holes 21, and similarly, a trajectory where 50% overlaps passes twice and a trajectory where 75% overlaps is The trajectory passes four times. Although it depends on the ball filling conditions, in many cases, the ball filling mistake around the moving area is higher than the center part, and therefore, the peripheral part of the moving area should preferably partially overlap the trajectory.

  Even if the ball B naturally falls on the flux 102, the ball B is light and the fall distance is short, so the ball B does not enter the flux 102 and easily moves. Therefore, as an example, the gap between the flux 102 and the mask lower surface 20b may be set to 30 μm so that the ball B is pushed into the flux 102 by 10 μm. When the ball B is pushed into the flux 102, the ball B can be fixed to such an extent that it does not move with a small force. Furthermore, the ball B can be fixed with a large force by pushing the ball B into the flux 102. On the other hand, this step 203 focuses on increasing the filling rate of the ball B, and fixing the ball B is left to the next step 204 as one method.

  In step 204, the press head 50 is moved independently of the head 30 so as to follow the movement of the head 30, and the transferred ball B is pushed into the flux 102. The start of step 204 may be almost the same as the start of step 203, a short time after the start of step 203, or after the end of step 203.

  The press head 50 is moved before the area filled with the balls B, and the press head 50 is lowered. The ball B filled in the hole 21 of the mask 20 is pressed toward the substrate 100 with an appropriate force by the press portion 51 biased by the spring 52. The ball B is pushed into the flux 102, and the contact area with the flux 102 is increased, so that the ball is satisfactorily fixed to the substrate 100. In step 203, if the force with which the flux 102 fixes the ball B is large enough not to cause a problem in the process, step 204 can be omitted.

  The height of the upper surface 20a of the mask 20 may be set in advance at a position higher than the apex of the ball B mounted on the electrode 101 by a height d. In this case, as shown in FIG. 9, since the ball B is pressed together with the mask 20, the vicinity of the area pressed by the press head 50 on the upper surface 20a of the mask 20 is lowered by the height d. Therefore, in the region where the press head 50 presses the mask 20, the filled ball B can be used as a spacer that does not allow the flux 102 to adhere to the mask 20 unless the problem of deformation or movement of the ball B is taken into consideration.

  Alternatively, the ball B pressing step can be performed after the ball B filling step without simultaneously filling and pressing the ball B. In this case, the mask 20 may be lowered to reduce the distance between the mask 20 and the flux 102 (for example, 10 μm), and the press head 50 may press only the ball B without pressing the mask 20.

  As described above, the ball mounting apparatus 1 allows the head 30 to be moved in a state where the mask 20 is magnetically attracted to the attracting portion 34 of the head 30 so that the distance S between the attracting portion 34 and the substrate is a predetermined distance. Since it moves, even if it is the mask 20 with the flat lower surface 20b, the clearance gap S1 with the board | substrate 100 can be hold | maintained at the desired space | interval.

  The mask 20 having a flat lower surface 20b is advantageous in that the flux 102 hardly adheres to it and can reduce the number of manufacturing steps. Further, there is no need for cleaning, and the flux can be easily removed even when cleaning. Further, when the warp of the substrate 100 cannot be corrected and is fixed to the support base 11, the distance S between the suction portion 34 and the substrate 100 is made more constant by controlling the height of the head 30 along with the movement of the moving area. can do. Furthermore, the distance S between the suction portion 34 and the substrate 100 can be intentionally changed depending on the positions of the center and the peripheral portion of the substrate 100.

  When the ball filling is completed, the head 30 is moved to the retracted position. Next, the stage 10 is lowered to separate the substrate 100 from the mask 20. After moving horizontally to the position (unloader) where the substrate 100 is taken out, the vacuum suction is stopped and the push pin is pushed up to separate the substrate 100 from the support 11 and move to the next step. The next process is a repair process or a reflow process. Note that a step of inspecting whether or not the mounted ball has a mounting error may be provided before the substrate 100 is removed.

  Further, since the ball B remains in the ball holding portion 32 of the head 30, the head 30 is raised, the ball B is removed, and a new ball can be used in the next filling operation. However, in the case of the ball filling condition in which the ball B is hardly damaged after filling the ball, the ball B remaining in the ball holding portion 32 may not be replaced. Further, if there is a residual ball remaining on the mask 20, it is removed with a squeegee. The squeegee can be retracted upward while the squeegee is not used for cleaning the ball.

  The upward reaction force generated when the mask 20 is pressed downward by the press head 50 is different between the central portion and the peripheral portion of the mask 20, so that the pressed state of the ball B varies depending on the location. In order to avoid this variation, after setting the mask 20 not to contact the press head 50, the ball B is pressed so that only the ball B can be substantially pressed. In this case, when the counter-balanced press head 50 is used, the ball B can be favorably pressed into the flux 102.

  Next, the magnetic attraction force and friction force between the head 30 and the mask 20 that are generated when the head 30 is moved will be briefly described. Unlike the vacuum suction, the apparatus 1 can stably support the mask 20 by the head 30 even if there are a plurality of holes 21. Further, when the head 30 is moved in a state where the mask 20 and the head 30 are attracted, a change in resistance (magnetic resistance) between the mask 20 and the head 30 hardly occurs in most ranges. However, in the periphery of the substrate 100, the number of the holes 21 of the mask 20 existing in the region magnetically coupled to the head 30 changes with the movement of the head 30, so that the mask 20 applies a force in a direction in which the magnetic resistance is small. Receive more. These changes in magnetoresistance are relatively small. Therefore, the resistance generated when moving the head 30 is mainly the frictional resistance between the head 30 and the mask 20. According to this ball mounting apparatus 1, since the magnetic flux moving in and out of the head 30 moves with almost no change, the force required for the head 30 to move the ball B on the mask 20 is small.

  FIG. 10 shows another example of the head. The head 30 a rotates around an axis 37 perpendicular to the mask 20. The rotation direction of the head may be, for example, clockwise as viewed from the lower side as shown by an arrow A3 in FIG. 10 or counterclockwise when viewed from the lower side, or may be changed in the middle.

  When a rotary head is used, a protrusion 90 for pushing away (sweeping) the ball may be provided on the inner wall surface F of the ball holding portion 32a. The number of the protrusions 90 is preferably 2-8. A region where the ball B exists in the moving area and a region where the ball B does not exist are formed by combining the ball stirring action generated by the rotation of the protrusion 90 and the ball stirring action generated by the trajectory movement of the head 30a. can do. Then, at the boundary portion between these regions, a portion having a single layer of balls and not being restrained by the balls can be formed. This one-layer portion of the ball B is an area where the ball B can be efficiently filled into the hole 21 of the mask 20. The protrusion 90 is preferably made of a magnetic material. The shape and material of the protrusion 90 are not limited to the above as long as the same effect can be obtained. Further, instead of the protrusion 90, a slit or hole for discharging gas is provided in the ball holding portion 32a, and when the ball B is agitated in the head I, the ball is misfilled or the ball bites between the head 30a and the mask 20 Can be reduced. The discharge of gas to the ball holding portion is not limited to this example, and is effective for other heads. The gas to be discharged is supplied from a blower or an inert gas high-pressure cylinder (not shown).

  FIG. 11 shows still another example of the head. The head 30b has a ball holding portion 32b including four electromagnets 92a and 92b. In the head 30b, the suction portion 34 at the tip of the ball holding portion 32b is magnetized to four poles, for example, SNS. In the head 30b, the adjacent magnetic poles are set to be different magnetic poles. This head 30b can be applied to the ball mounting apparatus 1 in place of the head 30 described above.

  By using such a head 30b, a magnetic circuit (closed circuit) can be formed by the mask 20 and the head 30b. By forming a magnetic closed circuit, the magnetic flux from the mask 20 and the head 30b can be prevented from leaking outside. Therefore, when there is a possibility that the substrate 100 is magnetically affected, it can be reduced.

  The means for generating the magnetic field is not limited to the coil, but may be a permanent magnet. Further, the magnetic poles of the attracting part are not limited to four poles. The number of magnetic poles of the attracting part can be arbitrarily determined. In addition, FIG. 11 shows an example in which the adsorption part of a head that vibrates in one direction as indicated by an arrow A4 along the XY plane is multipolarized, but the rotating type as shown in FIG. The adsorption part of the head may be multipolarized.

  The shape of the ball holding portion 32 is not limited to a bottomed cylindrical shape having an open end on the lower side. FIG. 12 shows still another example of the head. The head 30c is provided with a flat rectangular box-shaped ball holding portion 32c having an open end 31 on the lower side. The ball holding portion 32c has iron as a main component, and a conducting wire is wound around the outer periphery thereof (the coil 33 is provided). This magnetic circuit is composed of the head 30c, the mask 20, the frame of the ball mounting apparatus 1, and the like.

  When such a head 30c is used, the head 30c may be vibrated along the short side direction as indicated by an arrow A5. The head 30c may be moved along the long side direction as indicated by an arrow A6. Further, in the head 30c, the coil 33 may be omitted, and all or a part of the ball holding portion 32c (such as the vicinity of the attracting portion 34) may be formed by a permanent magnet. In addition, this head 30c can also make the adsorption | suction part 34 multipolar like the head 30b shown in FIG.

  FIG. 13 shows still another example of the head. This head 30d includes a box-shaped ball holding portion 32d having a flat square shape having an open end 31 on the lower side. The ball holding portion 32d is mainly composed of iron, and a conductive wire is wound around the outer periphery thereof (the coil 33 is provided). When such a head 30d is used, the head 30d is preferably vibrated along one arbitrary side as indicated by an arrow A7. Note that the head 30d may also be formed of a permanent magnet for all or part of the ball holding portion 32d (in the vicinity of the attracting portion 34) instead of the coil 33. When a permanent magnet is used for the magnetism generating portion, the mask 20 and the head 30d are magnetically attracted. Therefore, the head 30d and the mask 20 are carefully separated from each other around the mask 20. Furthermore, this head 30d can also make the adsorption part 34 multipolar, similarly to the head 30b shown in FIG.

  In the present invention, the ball mounting device 1 includes a ball mounting system including a substrate loader / unloader, a substrate correction device, a flux printing device, a mounting error inspection device, a repair device, and the like. Further, the ball mounting method and control method of the present invention is a method in which a magnetic circuit is formed between the head and the mask and the height of the mask can be arbitrarily adjusted by the head, and the relative height of the mask and the ball is controlled. It is not limited by the method of pressing the ball.

Sectional drawing which shows an example of a ball mounting apparatus. The bottom view which shows the head with which the ball | bowl mounting apparatus of FIG. 1 is provided. The figure which expands and shows the ball | bowl mounting apparatus of FIG. The figure which further expands and shows the ball mounting apparatus of FIG. The flowchart for demonstrating an example of the control method of a ball mounting apparatus. Sectional drawing which shows the other example of a ball mounting apparatus. The bottom view which shows the head with which the ball | bowl mounting apparatus of FIG. 6 is provided. The figure which expands and shows the ball | bowl mounting apparatus of FIG. The figure which further expands and shows the ball mounting apparatus of FIG. The bottom view which shows the other example of a head. FIG. 14 is a bottom view showing still another example of the head. FIG. 14 is a bottom view showing still another example of the head. FIG. 14 is a bottom view showing still another example of the head.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ball mounting apparatus, 20 Mask 20b Underside of mask, 21 Mask hole 30, 30a, 30b, 30c, 30d Head, 31 Open end 32, 32a, 32b, 32c, 32d of head Ball holding part 33 Coil, 34 Adsorption part 40 head moving device, 50 press head 60 press head moving device, 80 magnetism generating unit, 80a upper yoke 80b lower yoke, 81 spacer, 82 connecting unit 100 substrate, 100a upper surface B of substrate B conductive ball (ball), S adsorption unit And the top surface of the board

Claims (15)

A ball mounting device for placing microballs at a predetermined position on one surface of a substrate through a mask made of a magnetic body or a material containing a magnetic body, and having a plurality of holes filled with microballs. And
A head for moving a minute ball on the mask, the head having an adsorption portion that moves in a state of being attracted to the mask by a magnetic force;
A ball mounting device comprising: a moving device that moves the head so that a distance between the suction portion and one surface of the substrate is constant.   2. The ball mounting apparatus according to claim 1, wherein the head further includes means for generating a magnetic field.   2. The ball mounting apparatus according to claim 1, wherein the head surrounds a part of the mask by the suction part and / or by the movement of the suction part, and holds a group of minute balls in the enclosed area. .   4. The ball mounting apparatus according to claim 3, wherein the head includes a hollow ball holding portion having an opening end on a side facing the mask, and the opening end includes the suction portion.   4. The head according to claim 3, wherein the head is rotatable about an axis perpendicular to the mask, and by this rotation, a group of microballs is formed on a part of the mask so that the microballs are not scattered. A ball mounting device that can be held.   The ball mounting apparatus according to claim 1, wherein a surface of the mask facing the substrate is a flat surface.   The ball mounting apparatus according to claim 1, wherein the attracting portion is multipolar magnetized.   2. The ball mounting apparatus according to claim 1, further comprising a press head for pressing the fine balls filled in the holes of the mask toward the substrate.   9. The ball mounting device according to claim 8, further comprising a press head moving device that moves the press head, wherein the ball mounting device is capable of independently moving the head and the press head. A method of mounting a microball at a predetermined position on one surface of a substrate through a mask made of a magnetic body or a material containing a magnetic body, having a plurality of holes filled with microballs,
A head for moving a minute ball on the mask, the head having a suction portion that moves in a state of being attracted to the mask by a magnetic force, between the suction portion and one surface of the substrate Moving the spacing to be constant.   11. The method of claim 10, further comprising facing the mask to the substrate such that a gap is formed between the mask and the substrate.   The method according to claim 10, further comprising pressing the microballs filled in the holes of the mask toward the substrate. A control method of a ball mounting device for arranging microballs at a predetermined position on one surface of a substrate through a mask,
The ball mounting device is a head for moving a minute ball on a mask made of a magnetic material or a material containing a magnetic material, and having a plurality of holes filled with the minute ball, A head having a suction portion that moves while being attracted by a magnetic force;
A moving device for moving the head,
The said control method is a control method including moving the said head so that the space | interval of the said adsorption | suction part and the one surface of the said board | substrate may become fixed with the said moving apparatus.   The control method according to claim 13, wherein moving the head includes moving the head in a horizontal direction. The ball mounting device according to claim 13, wherein the ball mounting device presses the microballs filled in the holes of the mask toward the substrate;
A press head moving device for moving the press head;
The control method further includes moving the press head so as to follow the movement of the head by the press head moving device.

Images