JP2008124076A - Solder ball loading method and solder ball loading apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively and surely load a fine solder ball with a solder ball loading method for loading fine solder balls on a substrate using a solder ball loading mask. <P>SOLUTION: The solder ball loading method includes the steps of arranging a flux 9 on an electrode 3 of the substrate 1, loading the solder ball 15 to the electrode 3 by providing, on the substrate 1, the solder ball loading mask 10 to which a ball throwing aperture 12 is formed at a position opposing to the electrode 3 and by attracting the solder ball 15 to the ball throwing aperture 12 by lowering pressure between the solder ball loading mask 10 and the substrate 1, removing the solder ball loading mask 10 from the substrate 1, and bonding the solder ball 15 to the electrode 3. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a solder ball mounting method and a solder ball mounting device, and more particularly to a solder ball mounting method and a solder ball mounting device for mounting a fine solder ball on a substrate using a solder ball mounting mask.

  In recent years, electronic devices typified by portable terminal devices have been rapidly reduced in size and thickness, and electronic components such as semiconductor devices mounted on these electronic devices are also required to be reduced in size and thickness. . On the other hand, the density of these electronic components is increasing, and the number of connection terminals tends to increase.

  As a method of mounting electronic components that meet these requirements, solder balls are used as external connection terminals, which are mounted on the surface of a mounting board such as a printed circuit board such as flip chip (FC) mounting. Many methods are being used. This flip chip mounting method is a method in which solder balls are mounted in advance on electrodes provided on a substrate of an electronic component, and mounting is performed by directly bonding the solder balls to the electrodes of the mounting substrate.

  For this reason, when using the surface mounting method using a solder ball, it is necessary to mount the solder ball on the substrate of the electronic component in advance. The solder ball mounting method for mounting the solder ball on the substrate is generally performed by disposing a flux on the electrode on which the solder ball of the substrate is mounted, then disposing the solder ball on the flux, and then soldering the solder ball. A method is used in which a ball is heated and melted and joined to an electrode (see, for example, Patent Document 1).

  FIG. 5 is a diagram for explaining a specific example of a conventional solder ball mounting method. FIG. 5A shows the substrate 100. In this substrate 100, a solder resist 104 is formed on the upper surface of the substrate body 102, and an insulating film 105 is formed on the lower surface. A plurality of electrodes 103 are formed on the upper surface of the substrate 100, and an opening 106 is formed on one side of the solder resist 104 facing the electrode 103.

  In order to mount the solder balls 115 on the substrate 100, the substrate 100 is held on the stage 140 and a flux mask 108 is disposed on the substrate 100 (solder resist 104). A plurality of suction holes 141 are formed in the stage 140, and the substrate 100 is held by being sucked by the stage 140.

  The flux mask 108 has an opening at a position facing the opening 106. Then, the flux 109 is disposed in the opening 106 by printing or the like using the flux mask 108. FIG. 5B shows a state in which the flux 109 is disposed in the opening 106.

  When the disposition of the flux 109 to the opening 106 is completed, the flux mask 108 is removed, and subsequently, as shown in FIG. 5C, the ball mounting mask 110 is disposed on the substrate 100 (solder resist 104). Is done. The ball mounting mask 110 has a plurality of ball transfer openings 112 for mounting (transferring) the solder balls 115 onto the flux 109.

  When the ball mounting mask 110 is disposed on the substrate 100, a solder ball 115 is supplied onto the ball mounting mask 110, and the solder ball 115 is inserted into the ball transfer opening 112 using a squeegee (not shown) or the like. Transfer in. FIG. 5D shows a state in which the solder ball 115 is transferred into the opening 112. In this state, each solder ball 115 is mounted (temporarily fixed) on the upper part of the viscous flux 109.

When the solder ball 115 is mounted on the flux 109, the ball mounting mask 110 is removed from the substrate 100 as shown in FIG. Subsequently, a heat treatment such as a reflow process is performed to join the solder balls 115 to the electrodes 103, and then a flux 109 is washed to complete the substrate 100 on which the solder balls 115 are mounted.
JP 2006-005276 A

  However, when the solder ball 115 is simply transferred to the ball transfer opening 112 of the ball mounting mask 110 using a squeegee or the like as in the conventional solder ball mounting method, a ball transfer opening 112 that is not transferred is generated (this is the case). Missing balls).

  This missing ball is said to be a problem of probability and has been generated to some extent in the solder ball mounting process. When a missing ball is generated in this way, the occurrence location of the missing ball is specified by performing an inspection process, and the solder ball 115 is individually mounted on the occurrence location using a jig or the like ( This process is called repair process).

  However, as described above, the density of electronic components is increasing and the number of connection terminals tends to increase, and accordingly, it is required to mount the solder balls 115 on the substrate 100 at a high density. In order to meet this demand, the solder balls 115 tend to be miniaturized, and solder balls having a diameter of 100 μm are being put into practical use.

  When the diameter of the solder ball 115 is reduced in this way, a large number of missing balls are generated in the conventional solder ball mounting method, which requires frequent repair processing, and the efficiency of the solder ball mounting processing is significantly reduced. There was a problem.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a solder ball mounting method and a solder ball mounting apparatus capable of mounting a fine solder ball on a substrate efficiently and reliably.

In order to solve the above problems, in the present invention, in a solder ball mounting method for mounting a solder ball on an electrode formed on a substrate,
A flux disposing step of disposing a flux on the electrode of the substrate;
A solder ball mounting mask having a ball transfer opening formed at a position facing the electrode is disposed on the substrate, the pressure between the solder ball mounting mask and the substrate is reduced, and the solder is mounted in the ball transfer opening. A solder ball mounting step of mounting the solder ball on the electrode by sucking the ball;
Removing the solder ball mounting mask from the substrate;
Joining the solder balls to the electrodes.

  In the above invention, the insulating material may be a solder resist.

Further, in order to solve the above problems, in the present invention, in a solder ball mounting apparatus for mounting a solder ball on an electrode formed on a substrate,
A solder ball mounting mask in which a ball transfer opening facing the electrode in a state of being mounted on the substrate is formed;
There is provided pressure reducing means for reducing the pressure between the substrate and the solder ball mounting mask and sucking the solder ball into the ball transfer opening during the mounting.

In the above invention, the decompression means includes
A decompressor;
A mounting housing in which the solder ball mounting mask is mounted in an airtight manner and connected to the decompression means;
It is good also as a structure which is formed in the surface facing the said board | substrate of the said solder ball mounting mask, and has a pressure-reduction path | route with one end connected to the said ball transfer opening, and the other end connected to the said housing | casing for apparatuses.

  According to the present invention, the pressure between the solder ball mounting mask and the substrate is reduced, and the solder ball is mounted on the electrode by sucking the ball into the ball transfer opening. Solder balls can be transferred. Thereby, generation | occurrence | production of what is called a missing ball can be decreased, the frequency | count of a repair process is also reduced, and a solder ball can be efficiently and reliably mounted in an electrode.

  Next, the best mode for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 is a configuration diagram showing a solder ball mounting apparatus 20 according to an embodiment of the present invention. In short, the solder ball mounting device 20 includes a ball mounting mask 10, a mask mounting housing 30, a stage 40, vacuum pumps 50 and 60 (pressure reduction devices), and the like.

  The ball mounting mask 10 is a metal mask, and a plurality of ball transfer openings 12 for mounting the solder balls 15 on the substrate 1 are formed. The diameter of the ball transfer opening 12 is set to be slightly larger than the diameter of the solder ball 115, and the difference in diameter is set to a value that can be transferred appropriately.

  Further, a concave portion is formed on the back side of the ball mounting mask 10 (the surface facing the substrate 1). Therefore, when the ball mounting mask 10 is disposed on the substrate 1, the substrate 1 and the ball mounting A space 11 is formed between the mask 10 for use. A plurality of communication grooves 13 are formed in the outer peripheral portion of the recess. The communication groove 13 has a function of communicating an internal space 31 and a space portion 11 described later.

  The mask mounting housing 30 is a housing with an upper opening, and forms an internal space 31 inside. Further, the opening side end portion of the mask mounting housing 30 is a mounting portion 32 for mounting the ball mounting mask 10.

  Further, a connection hole 33 is provided in the lower portion of the mask mounting housing 30, and the connection hole 33 is connected to the vacuum pump 50 via a suction pipe (not shown). The mounting portion 32 is provided with a packing material such as rubber, so that the airtightness between the ball mounting mask 10 and the mounting portion 32 is enhanced when the ball mounting mask 10 is mounted.

  The stage 40 has a function of holding the substrate 1 and is disposed inside the mask mounting housing 30. The stage 40 is configured to include a stage unit 43 and a support column unit 44. In this stage 40, a plurality of suction holes 41 are formed in the stage portion 43 for holding the substrate 1 of the stage 40.

  Further, the support column 43 extending downward from the stage unit 43 extends through the mask mounting housing 30 to the outside of the mask mounting housing 30. The column portion 44 has a communication passage 42 formed therein, one end portion of the communication passage 42 communicates with the suction hole 41, and the other end portion is connected to the vacuum pump 60 via a suction pipe (not shown). Yes.

  As will be described later, in the ball mounting process of mounting the solder balls 15 on the substrate 1, the ball mounting mask 10 is mounted on the mask mounting housing 30 while the substrate 1 is held on the stage 40. In this mounted state, the ball mounting mask 10 is placed on the substrate 1 and the mounting portion 32. Further, when the ball mounting mask 10 is mounted on the top of the mask mounting housing 30, the internal space 31 forms a closed space.

  Further, the communication groove 13 formed on the back surface of the ball mounting mask 10 includes a space portion 11 formed between the substrate 1 and the ball mounting mask 10 and an internal space 31 of the mask mounting housing 30. Communicate. Therefore, when the vacuum pump 50 is driven and the internal space 31 is depressurized, the space 11 is also depressurized via the communication groove 13. Since the outside of the ball mounting mask 10 is atmospheric pressure, the air is sucked from the ball transfer opening 12 when the space 11 is depressurized, and the solder ball 15 is also sucked into the ball transfer opening 12 accordingly.

  Further, when the internal space 31 is depressurized, the ball mounting mask 10 is also sucked and pressed against the mounting portion 32, so that the ball mounting mask 10 is securely held by the mask mounting housing 30. When the ball mounting mask 10 is mounted on the mask mounting housing 30, the electrode 3 of the substrate 1 and the ball transfer opening 12 are positioned. Since the pressure is surely held by the mask mounting housing 30 by reducing the pressure, the positioning is not shifted.

  As described above, the solder ball mounting device 20 according to the present embodiment is configured to suck the solder ball 15 into the ball transfer opening 12 and fix the ball mounting mask 10 to the mask mounting housing 30. Therefore, the apparatus configuration can be simplified as compared with the case where each is provided separately. In this embodiment, the vacuum pump 50 and the vacuum pump 60 are configured separately. However, the vacuum pump 50 and the vacuum pump 60 are separately configured to hold the substrate 1 on the stage 43 and to perform the decompression process in the space 11. It is also possible to do.

  Next, a solder ball mounting method according to an embodiment of the present invention will be described with reference to FIGS. The solder ball mounting method described below is performed using the solder ball mounting apparatus 20 described above. 2 to 4, the same components as those shown in FIG. 1 described above are denoted by the same reference numerals, and the description thereof is omitted. 2A and 2B, the mask mounting housing 30 is not shown for convenience of explanation.

  FIG. 2A shows the substrate 1 held on the stage 40 and provided with the flux 9 using the flux mask 8. The substrate 1 includes a substrate body 2, a solder resist 4 formed on the upper surface of the substrate body 2, and an insulating film 5 formed on the lower surface of the substrate body 2.

  Various types of substrates such as a resin substrate, a ceramic substrate, a wafer, and a built-up substrate can be applied to the substrate body 2. A plurality of electrodes 3 are formed on the upper surface of the substrate body 2.

  In this embodiment, an example in which a wafer is used as the substrate body 2 will be described. A large number of element regions are formed on the wafer. In each of FIGS. 2 to 4, only one element region of the wafer is shown as an enlarged substrate body 2.

  The solder resist 4 is an insulating material provided to suppress a solder short during the soldering process, and is formed with a predetermined thickness (for example, 30 to 40 μm) on the entire upper surface of the substrate body 2 by using, for example, a printing method. ing. An opening 6 is formed at a position facing the electrode 3 of the solder resist 4. Therefore, before the flux 9 is disposed, the electrode 3 is exposed at the position where the opening 6 is formed.

  The insulating film 5 is provided to protect the back surface of the substrate body 2. The insulating film 5 is not necessarily provided, and the method of the present invention can be realized even if the insulating film 5 is not present.

  In order to arrange the flux 9 on the substrate 1, the substrate 1 is placed on the stage 40, and then the vacuum pump 60 is activated to attract the substrate 1 to the stage portion 43 through the suction holes 41. As a result, the substrate 1 is held on the stage 40. Next, a flux mask 8 is disposed on the substrate 1. The flux mask 8 is a metal mask and has an opening corresponding to the opening 6.

  When the flux mask 8 is disposed on the substrate 1, the flux 9 is disposed in the opening 6 using the flux mask 8 (flux disposing step). As a method for disposing the flux 9 in the opening 6, for example, a printing method can be used. When the arrangement process of the flux 9 is completed, the flux mask 8 is removed from the substrate 1 as shown in FIG.

  Subsequently, as shown in FIG. 2C, a ball mounting mask 10 is disposed on the substrate 1. The ball mounting mask 10 is disposed by first positioning the ball transfer opening 12 formed in the ball mounting mask 10 and the electrode 3 of the substrate 1 and placing the ball mounting mask 10 on the substrate 1. . At this time, the substrate 1 is maintained in the state of being held on the stage 40.

  In a state where the ball mounting mask 10 is placed on the substrate 1, the outer peripheral portion of the ball mounting mask 10 is also placed on the mounting portion 32 of the mask mounting housing 30. When the ball mounting mask 10 is thus placed on the substrate 1 and the mounting portion 32 (mask mounting housing 30), the vacuum pump 50 is activated and the internal space 31 is depressurized.

  As described above, the communication groove 13 formed on the back surface of the ball mounting mask 10 communicates the space portion 11 and the internal space 31. Therefore, when the vacuum pump 50 is driven and the internal space 31 is depressurized, the space 11 is also depressurized via the communication groove 13.

  At the same time, the internal space 31 becomes negative pressure, so that the ball mounting mask 10 is attracted to the mounting portion 32. At this time, since a packing material is provided in the mounting portion 32, no leak occurs between the ball mounting mask 10 and the mounting portion 32.

  Since the outside of the ball mounting mask 10 is at atmospheric pressure, the air is sucked from the ball transfer opening 12 by reducing the space 11. In this state, as shown in FIG. 3A, the solder ball 15 is supplied onto the ball mounting mask 10, and the solder ball 15 is transferred into the ball transfer opening 12 using the squeegee 14 (solder ball mounting step).

  As described above, in this embodiment, the solder ball 15 is attracted to the ball transfer opening 12 and mounted on the electrode 3, so that the solder ball 15 can be reliably transferred to the ball transfer opening 12 even if the solder ball 15 is miniaturized. it can. In particular, as shown in FIG. 3A, since there are a large number of solder balls 15 at the start of transfer of the solder balls 15 to the ball transfer openings 12, the transfer rate to the ball transfer openings 12 is high.

  However, as the squeegee 16 moves to the right in FIG. 3A and the solder balls 15 are sequentially loaded into the ball transfer opening 12, the number of solder balls 15 moved by the squeegee 16 decreases, and the ball transfer is performed. It becomes difficult for the solder ball 15 to be transferred into the opening 12.

  However, since the ball transfer opening 12 is blocked by the solder ball 15 when the solder ball 15 is transferred to the ball transfer opening 12 and mounted on the electrode 3 (flux 9), the ball transfer without the solder ball 15 being transferred is performed. The suction force of the opening 12 increases. As a result, even if the number of solder balls 15 moved by the squeegee 16 decreases as described above, the suction force of the ball transfer opening 12 to which the solder balls 15 are not transferred is increased accordingly. The transfer rate of the solder balls 15 to 12 can be maintained high.

  As a result, the solder balls 15 can be reliably transferred to all the ball transfer openings 12. Therefore, the occurrence of missing balls can be suppressed, the number of repair processes can be reduced, and the solder balls 15 can be mounted on the electrodes 3 efficiently and reliably.

  FIG. 4A shows a state in which solder balls 15 are transferred to all the ball transfer openings 12 and mounted on the electrodes 3 (flux 9). In this state, each solder ball 15 is mounted (temporarily fixed) on the viscous flux 9. When the mounting process of the solder balls 15 is completed, the vacuum pump 50 is stopped. However, even in this state, the vacuum pump 60 is driven, and the substrate 1 is maintained in the state of being held on the stage 40.

  Subsequently, as shown in FIG. 4B, the ball mounting mask 10 is removed from the substrate 1. Next, the vacuum pump 60 is stopped, the substrate 1 is removed from the solder ball mounting device 20 and loaded into a reflow furnace, and a process of joining the solder ball 15 to the electrode 3 is performed. FIG. 4C shows a state where the solder ball 15 is bonded to the electrode 3.

  When the solder balls 15 are joined to the electrodes 3, the cleaning process of the flux 9 is subsequently performed, and the substrate 1 on which the solder balls 15 are mounted on the electrodes 3 shown in FIG. 4D is completed.

  The application of the present invention is not limited to a wafer, but can also be applied to a substrate body 2 using a build-up substrate. Further, the position of the solder ball 15 is not limited to one side of the substrate body 2, and the present invention can be applied to the case where the solder ball 15 is disposed on both sides of the substrate body 2.

FIG. 1 is a configuration diagram for explaining a solder ball mounting apparatus according to an embodiment of the present invention. FIG. 2 is a diagram for explaining a solder ball mounting method according to an embodiment of the present invention (part 1). FIG. 3 is a view for explaining a solder ball mounting method according to an embodiment of the present invention (part 2). FIG. 4 is a view for explaining a solder ball mounting method according to an embodiment of the present invention (part 3). FIG. 5 is a diagram for explaining a solder ball mounting method as an example of the prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Board | substrate 2 Board | substrate body 3 Electrode 4 Solder resist 6 Opening part 8 Flux mask 9 Flux 10 Ball mounting mask 12 Ball transfer opening 15 Solder ball 20 Solder ball mounting apparatus 30 Mask mounting housing 32 Mounting section 40 Stages 50, 60 Vacuum pump

Claims (4)

In the solder ball mounting method of mounting solder balls on the electrodes formed on the substrate,
A flux disposing step of disposing a flux on the electrode of the substrate;
A solder ball mounting mask having a ball transfer opening formed at a position facing the electrode is disposed on the substrate, the pressure between the solder ball mounting mask and the substrate is reduced, and the solder is mounted in the ball transfer opening. A solder ball mounting step of mounting the solder ball on the electrode by sucking the ball;
Removing the solder ball mounting mask from the substrate;
Joining the solder ball to the electrode.   The solder ball mounting method according to claim 1, wherein the insulating material is a solder resist. In a solder ball mounting device that mounts solder balls on electrodes formed on a substrate,
A solder ball mounting mask in which a ball transfer opening facing the electrode in a state of being mounted on the substrate is formed;
A solder ball mounting apparatus, comprising: a pressure reducing means for reducing a pressure between the substrate and the solder ball mounting mask and sucking the solder ball into a ball transfer opening during the mounting. The decompression means includes
A decompressor;
A mounting housing in which the solder ball mounting mask is mounted in an airtight manner and connected to the decompression means;
The solder ball mounting mask includes a decompression passage formed on a surface of the solder ball mounting mask facing the substrate and having one end communicating with the ball transfer opening and the other end communicating with the apparatus housing. Item 3. A solder ball mounting apparatus according to Item 2.

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