JPH1140615A - Method and apparatus for mounting solder balls - Google Patents

Abstract

PROBLEM TO BE SOLVED: To absolutely prevent over-mounting of solder balls, by permitting the solder balls to be attracted to suction holes of a suction head having turned- down suction surface, spraying a gas with injection nozzles over the entire suction surface from beneath in an oblique direction, and completely removing only the solder balls statically attracted to portions which do not require solder balls. SOLUTION: A suction head 1 has a box-like shape with its inside being vacant. The lower portion of the suction head 1 serves as a suction surface 4 wherein a plurality of suction holes 3, respectively, corresponding to the positions for forming bumps for electronic parts, are punched. After solder balls are sucked to the suction holes 3, the suction condition is detected. Further, an injection system 6 is permitted to move beneath the suction head 1 while injecting a gas from injection nozzles 9, so that the gas successively strikes the suction surface 4 from one end to the other. Since those solder balls on the portions of the suction surface 4 which do not require solder balls, are attracted thereto merely in a static manner, the bonding strength is so weak as to be readily flown off by the injected gas, while the solder balls attracted to the suction holes 3 are hardly flown off by the gas injection force.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for mounting a spherical solder, particularly a fine spherical solder, on an electronic component.

[0002]

2. Description of the Related Art In recent years, as electronic devices have become lighter, thinner and smaller, electronic components used in the electronic devices have become smaller and more multifunctional. In order to make an electronic component multifunctional, a large number of ICs must be incorporated in the component and a large number of leads must be drawn from the IC. Therefore, it is necessary to provide as many external leads as possible. The multifunctional electronic components include QFP, SOIC
These electronic components have a large number of leads on both sides or four sides of the component body. However, since QFPs and SOICs, etc., have leads installed on the side surface of the main body, the number of leads is limited.
It was about a book.

[0003] Therefore, today, BGAs (Balls) which have more functions by adding more leads than QFPs and SOICs have been developed.
Grid Array), CSP (Chip Siz)
High-performance electronic components such as ePackage) and flip chips have emerged. The BGA or CSP has an IC mounted on an upper surface of a substrate, and dot-like leads connected to the IC are provided at lattice positions on the back surface of the substrate. The flip chip has a point-like lead directly provided on the back surface of the IC. High-performance electronic components such as BGA, CSP, and flip-chip are provided with point-like leads in a wide area, so that a large number of leads can be provided, and the function is excellent.

In order to mount this high-performance electronic component on a printed circuit board, a solder bump is formed in advance on the lead of the high-performance electronic component, and the bump is mounted in accordance with the mounting of the printed circuit board. Is melted and soldered. In the method of forming the solder bumps, a flux is applied to a point-like lead of a high-performance electronic component, a spherical solder is placed thereon, and then heated by a heating device such as a reflow furnace to melt the spherical solder.

[0005] Mounting of spherical solder on high-performance electronic parts
The suction head having a large number of suction holes is placed so that the suction holes face downward, and the suction head is brought closer to a storage container containing a large number of spherical solders. Then, with the suction head in a vacuum state, that is, in a state of being sucked through the suction hole, the spherical solder in the storage container is sucked into the suction hole of the suction head.

At this time, if the suction head is left in a vacuum state, the ball solder does not always come into contact with all the suction holes. It cannot absorb solder. Then, after bringing the suction head close to the storage container, gas is blown out from the bottom surface of the storage container to lift up the spherical solder, and the lifted spherical solder is sucked into the suction hole of the suction nozzle (floating method: Japanese Patent Laid-Open No. 7-1995).
No. 307340), a spherical solder, which moves randomly by vibrating a storage container, is sucked into a suction hole (vibration method: Japanese Patent Application Laid-Open No. 7-302796), or a suction nozzle is fitted into the storage container and then stored with the suction nozzle. The spherical solder is sucked into the suction holes by rotating the container at a fixed angle and rolling the spherical solder on the suction holes of the suction head (rotation method: JP-A-8-255997).

In general, most of the spherical solders used for the BGA have a diameter of 0.76 mm, and a slightly smaller BGA may use a 0.7 mm diameter spherical solder. However, in the case of a CSP, a very small spherical solder having a diameter of 0.3 mm or less is used for a spherical solder, and particularly a recent ultra-compact CSP or flip chip has a diameter of 0.15 mm.

[0008]

The spherical solder having a diameter of 0.76 mm used in the BGA is sucked to the suction head by a floating method, a vibration method, a rotation method, or the like, and then separated from the storage container and the suction head. Meanwhile, the spherical solder that has adhered to portions other than the suction holes falls into the storage container by its own weight, and most of the solder does not adhere to the suction head other than the suction holes. However CSP
In some cases, a spherical solder having a diameter of 0.3 mm or less, such as used for a chip or a flip chip, is adsorbed to a suction head and then separated from a storage container, so that it may remain attached to a portion other than the suction hole.

[0009] This is because when the minute spherical solder is suspended in gas or moved by vibration or rotation, it is rubbed between the spherical solders or between the spherical solder and the wall surface of the storage container and becomes charged with static electricity. Because of this, the static electricity causes the spherical solder to adhere to unnecessary portions other than the suction holes of the suction head (hereinafter, simply referred to as unnecessary portions).

[0010] As described above, CS is adhered to unnecessary portions.
When spherical solder is mounted on P or flip chip, the spherical solder becomes excessively mounted, and when it is heated in a reflow furnace to melt the spherical solder, two spherical solders are fused at one bump formation location As a result, an excessively large bump is generated, or a defect that adjacent bumps are integrated to form a bridge is generated.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method and an apparatus for mounting a spherical solder in which only the spherical solder attached to an unnecessary portion due to static electricity is completely removed and no excessive mounting is caused.

[0012]

As means for removing minute spherical solder adhering to the suction head by static electricity, sweeping the suction head with a brush, applying an impact to the suction head, or applying gas to the suction head. Or spraying.

[0013] The sweeping means using a brush removes even the necessary spherical solder adsorbed in the suction holes if the brush bristles are strong or the tips of the brushes hit the suction head deeply. Therefore, there is a problem that it is very difficult for the sweeping means to select the bristles of the brush and to adjust the degree of contact with the suction head.

Although the means for impacting the suction head is effective for removing the spherical solder adhering to an unnecessary part to a certain extent, the state of removal varies depending on the strength of the shock and the place where the shock is applied. However, it is time-consuming to change the size of the spherical solder and the number of mounted spherical solders as needed.

[0015] The gas blowing means is capable of removing unnecessary spherical solder only by adjusting the blowing strength according to the size of the spherical solder, and has a smaller adjustment factor than other means, so that adjustment is easy. It is. However, simply applying gas to the suction surface of the suction head cannot completely remove the spherical solder attached to unnecessary portions.

The inventor of the present invention has conducted intensive studies on completely removing spherical solder adhered to unnecessary portions by using a gas blowing means which is easy to adjust and is most effective for removing spherical solder adhered to unnecessary portions. To complete the present invention.

According to the present invention, there is provided a method of mounting a spherical solder at a predetermined position on an electronic component, wherein the spherical solder sucked into the suction hole of the suction head is mounted on the suction hole of the suction head whose suction surface faces downward. After the gas is adsorbed, unnecessary gas solder adhering to places other than the suction holes is removed by spraying a gas from obliquely downward on the entire suction surface with a jet nozzle. In addition, a suction head having a large number of suction holes is installed with the suction surface facing downward, and a row of ejection nozzles is installed below the suction head. The nozzle has a gas ejection direction inclined with respect to the suction surface, and is moved so that the ejection nozzle or suction head can blow gas from the ejection nozzle onto the entire suction surface of the suction head. It is equipped with apparatus spherical solder, characterized in that is possible.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, when blowing a gas onto an adsorption surface, the gas must hit the adsorption surface in an inclined state. This is because when the gas is blown at right angles to the suction surface, the gas will lift the spherical solder from below, so the spherical solder will adhere to the suction surface further and remove the spherical solder attached to unnecessary parts Because you can't. The inclination angle at which the gas hits the adsorption surface is 3 degrees or more measured from the vertical direction.
It is desirably 60 degrees or less.

In the present invention, the gas blown to the suction head may be air, but using an inert gas such as nitrogen, argon or helium is more effective for stabilizing the quality of the spherical solder. In other words, when the spherical solder is sucked by the suction head, it is not easily sucked into the suction holes, and the spherical solder that adheres to unnecessary places many times is exposed to air more frequently, so the surface of the spherical solder is oxidized by air. This may cause soldering failure during reflow after being mounted on the electronic component.

In the present invention, the removal of the spherical solder adhering to the unnecessary portion can be performed only by blowing the gas. However, the use of the impact means to the suction head can further remove the solder reliably. This is because when a large amount of spherical solder adheres to one location, if a large amount of spherical solder is blown off by the gas that is blown out, it is feared that the amount and momentum will also fly together with the spherical solder that was adsorbed in the suction hole. This is because that. Therefore, it is necessary to apply a shock to the suction head to remove this large amount of spherical solder that has adhered in advance by applying a shock to the suction head, and then blow gas to remove the spherical solder that has adhered to unnecessary parts. It is possible to remove only the spherical solder adhering to an unnecessary portion while leaving a good spherical solder.

As described above, when the 0.76 mm diameter spherical solder for BGA adheres to an unnecessary portion, most of the spherical solder falls under its own weight. The present invention can also be applied to a case where the object does not fall. However, it is often the case that the spherical solder having a diameter of 0.3 mm or less easily adheres to unnecessary portions due to electrostatic charging, and the present invention exerts the most excellent effect on the spherical solder having a diameter of 0.3 mm or less. .

The apparatus for mounting a spherical solder according to the present invention uses an apparatus in which ejection nozzles are arranged in a row. The row-like arrangement refers to an arrangement in which ejection nozzles having a large number of holes are arranged in a straight line, or an elongated slit. It is a squirt nozzle. When a slit is used for the ejection nozzle, the slit can be sprayed over the entire suction head, so that there is no concern about a dead zone.

A jet nozzle having a large number of jet nozzles arranged in a straight line forms a so-called dead zone between one jet nozzle and an adjacent jet nozzle, in which gas does not strike the suction head. Therefore, when using a jet nozzle having a large number of holes, the suction nozzle itself is advanced so as to reciprocate laterally in the advancing direction so that a dead zone is not formed.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of a mounting device for a spherical solder according to the present invention, and FIG. 2 is a front sectional view of the same.

The suction head 1 has a box shape with a hollow inside. A suction plug 2 communicating with the inside is installed on a side surface of the suction head 1, and the suction plug is connected to a suction device (not shown) by a pipe. The lower part of the suction head is a suction surface 4 having a plurality of suction holes 3... A transparent tempered glass 5 is fitted into the upper part of the suction head 1 in a state where the inside is sealed. The reason why the upper part is made of a transparent tempered glass is to detect the suction state of the spherical solder in the suction hole. . That is, after the spherical solder is adsorbed by the suction hole,
Laser light or halogen light is emitted from above the suction head, and the light is received by a light receiving device installed below the suction head. At this time, if the spherical solder is not adsorbed to any one of the suction holes, light passes through the suction hole and is received by the lower light receiving device. Then, the non-adsorption is notified by an alarm, or the adsorption step is performed again.

The ejection device 6 has a box shape with an open upper portion, and a lower portion has a two-stage bottom having a deep recovery portion 7 and a shallow ejection portion 8. A plurality of ejection nozzles 9 arranged in a straight line are formed in the ejection portion 8. The ejection direction of the ejection nozzle 9 is inclined with respect to the vertical line so as to face the traveling direction of the ejection device as shown in FIG. This inclination angle (α)
Is 3 to 60 degrees with respect to a vertical line, preferably 5 to 1
5 degrees. The ejection nozzle 9 communicates with a flow path 10 opened inside the ejection device 6, and an external inflow plug 11 is connected to the flow path. The inflow plug is connected to a gas pumping device (not shown) by a pipe.

Behind the blowing section 8 of the blowing device 6, a windbreak wall 1 is provided.
2 are erected. This windbreak wall is used to prevent, when the spherical solder adhering to an unnecessary portion of the suction head is blown off by the ejection nozzle, the collecting portion 7 from jumping backward or hitting another spherical solder and flying backward. It is assumed that.

The ejection device 6 advances below the suction head 1 so that the gas ejected from the ejection nozzle 9 strikes the suction surface 4 from one end to the other end sequentially. However, since the ejection nozzle 9 drilled in the ejection device 6 has a hole shape, a dead zone where gas does not reach between adjacent ejection nozzles is formed. Therefore, when a hole-shaped ejection nozzle is used, when the ejection device 6 is moved not only in the traveling direction but also while reciprocating in the direction perpendicular to the traveling direction as shown by the arrow A in FIG. 1, the ejection device becomes zigzag. , So that squirting without dead zone can be performed. In the embodiment of the present invention, the ejection device is moved below the suction head. However, the ejection device may be fixed and the suction head may be moved above the ejection device.

The suction head 1 is provided with an impact device 13. The impact device 13 is configured to move up and down in the direction of arrow X to apply an impact to the suction head.

Next, a method for mounting a spherical solder using the above-described apparatus for mounting a spherical solder will be described.

The spherical solder is sucked onto the suction surface 4 of the suction head 1 using an apparatus (not shown) employing a floating method, a vibration method, a rotation method, or the like. At this time, the spherical solder H charged with static electricity
Are attached to unnecessary portions of the suction surface 4. After adsorbing the spherical solder on the adsorption surface 4, first, an impact is applied to the adsorption head by the impact device 13 to remove a large amount of adhered spherical solder. At this time, all the spherical solder adhering to the unnecessary portion is not removed only by the impact on the suction head.

Thereafter, the ejection device 6 is moved below the suction head 1 as shown by an arrow A. In the ejection device 6, gas is sent to the inflow plug 11 from a gas pressure sending device (not shown), and the gas is ejected from the ejection nozzles 9. Since the ejection nozzle 9 is formed so as to be inclined with respect to the vertical line, the gas comes into contact with the suction surface 4 from obliquely below. Therefore, the suction hole 3 of the suction surface 4
The spherical solder H that has adhered to other locations is easily blown off by the blast gas. The blown-out spherical solder falls into the collecting section 7 of the jetting device 6 and is collected there.

The spherical solder adhering to the unnecessary portion of the suction surface 4 is adhered by static electricity, and therefore has a weak adhesive force and is easily blown off by the jetting gas. It is not blown away by force. Therefore, the suction head blown with gas by the ejection device,
The spherical solder adhering to unnecessary portions of the suction surface is completely removed, and only the spherical solder sucked in the suction holes remains.

The suction head from which the spherical solder adhered to the unnecessary portions has been removed in this manner is irradiated with light from above by a light emitting device (not shown). Light emitted from above the suction head passes through the transparent tempered glass 5 of the suction head 1 and enters each suction hole 3 from above. At this time, where the spherical solder is not sucked into the suction hole, the light passes through the suction hole and reaches a light receiving device (not shown) installed below.
The light receiving device that has received the light detects that the suction head has not been suctioned, and issues a warning or issues a command to restart the suction process.

The suction head in which no spherical solder adheres to unnecessary portions and the spherical solder is sucked in all the suction holes moves to the electronic component, and mounts the spherical solder on the bump forming portion of the flux-coated electronic component. I do. Then, the electronic component on which the spherical solder is mounted is heated by a heating device such as a reflow furnace, and the spherical solder is melted to form bumps.

In the present invention, when a spherical solder having a diameter of 0.15 mm was mounted on a CSP having 225 bump forming portions, no excessive or no spherical solder was mounted.

[0037]

As described above, according to the present invention,
A conventional mounting method that can reliably remove the minute spherical solder that adheres to the adsorption surface easily due to static electricity from unnecessary parts, eliminating excessive bumps and bridges due to excessive mounting, and enabling reliable bonding It has an excellent effect that cannot be obtained with a device.

[Brief description of the drawings]

FIG. 1 is a perspective view of a spherical solder mounting apparatus according to the present invention.

FIG. 2 is a front view of an apparatus for mounting a spherical solder according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Suction head 2 Suction plug 3 Suction hole 4 Suction surface 5 Tempered glass 6 Ejector 7 Recovery part 8 Ejector 9 Eject nozzle 10 Flow path 11 Inflow plug 12 Windproof wall 13 Impact device

Claims (7)

[Claims] 1. A method of mounting a spherical solder in a predetermined position on an electronic component, wherein the spherical solder sucked in the suction hole of the suction head is mounted on the electronic component. A method for mounting a spherical solder, comprising removing unnecessary spherical solder attached to portions other than the suction holes by blowing a gas obliquely downward from the ejection nozzle to the entire suction surface. 2. The method according to claim 1, wherein the gas is air. 3. The method according to claim 1, wherein the gas is an inert gas. 4. The method of mounting a spherical solder according to claim 1, wherein the removing of the spherical solder is performed by applying a gas to the suction head and then blowing the gas. 5. A suction head having a large number of suction holes is provided with its suction surface facing downward, and a row of ejection nozzles is provided below the suction head. The ejection nozzle has a gas ejection direction inclined with respect to the suction surface, and can be moved so that the ejection nozzle or the suction head can apply gas from the ejection nozzle to the entire suction surface of the suction head. A mounting device for a spherical solder. 6. The mounting apparatus according to claim 5, wherein the ejection nozzle has a large number of ejection holes arranged in a straight line. 7. The apparatus according to claim 5, wherein the ejection nozzle is a slit.