JP3087717B2 - How to remove excess adsorbed solder balls - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing excess suction solder balls from a solder ball suction plate used for forming solder bumps serving as connection electrodes.

[0002]

2. Description of the Related Art Solder bumps are widely known as connection electrodes formed on semiconductor chips and wiring leads.

In the case of forming the solder bumps, for example, as shown in FIG. 3, solder balls 4 are respectively attached to a plurality of (five in the figure) predetermined portions 2 on a circuit board 1 on which solder flags 3 are applied. Adsorption (mounting) is performed, and the solder balls 4 are melted to form solder bumps.

In this step, a solder ball mounting plate 5 having a through hole 6 facing each predetermined portion 2 and a solder ball carrier having a suction hole 8 having a smaller diameter than the solder ball 4 facing the predetermined portion 2 are formed. (Suction jig) 7 is used.

[0005] The suction jig 7 is connected to a vacuum device (not shown), and the air in the cavity 9 is sucked by the operation of the device.
Moves between the installation position of the circuit board 1 and a solder ball container (not shown) accommodating a large number of solder balls 4, and the solder balls are inserted into the respective through holes 6 of the mounting plate 5 mounted on the circuit board 1. 4
Insert.

Therefore, the circuit board 1 and the mounting plate 5 are heated together in a stacked state, and the solder balls 4 inserted into the through holes 6 of the mounting plate 5 are melted. Solder bumps are formed on the substrate.

[0007]

When the solder balls 4 are sucked on the suction surface 7a side of the solder ball suction jig 7 as shown in the figure, the solder balls 4 are held in a solder ball container containing a large number of solder balls 4. The surface 7a is put in and sucked by the suction force of air. At this time, a method is adopted in which the solder balls are vibrated by ultrasonic waves and sucked so that a predetermined number of solder balls 4 are accurately and smoothly sucked below the intake holes 8.

However, the method using the ultrasonic waves has a weak point. That is, there is a problem in that static electricity is generated due to friction between the solder balls vibrated by the ultrasonic waves, the solder balls attract each other, and an excess suction ball b is generated.

As a countermeasure against this point, there is a method of applying an ultrasonic vibration to the surplus suction ball b to shake it off, but it is not very effective. Because the solder balls 4 are originally adsorbed to the jig side by air, the surplus balls b
Removal must be done with a fairly weak force, whereas ultrasonic waves are applied to the solder balls not only to generate static electricity, but also to apply ultrasonic waves so that they do not fall down to solder balls that are normally adsorbed This is because it is difficult to control the intensity of the vibration, that is, the intensity of the vibration.

The present invention has been made in view of the above points, and it is possible to reliably and easily remove solder balls excessively adsorbed by an adsorption jig, and to use a simple device. It is an object of the present invention to provide a method for removing an excessively attracted solder ball, which can be realized by the above method.

[0011]

According to the present invention, there is provided a method of removing a solder ball excessively adsorbed on a suction surface of a solder ball suction jig. A method of removing using an electrostatic suction device that can be suctioned by the force of. In this case, it is also possible to remove the solder ball that has been excessively adsorbed on the suction surface by bringing the electrostatic suction device close to the suction ball with the suction surface of the suction jig positioned at the lower side. Further, when the excess solder ball is sucked by the electrostatic suction device, it is preferable that the surplus solder ball is sucked by a force weaker than the suction force of the solder ball by the suction jig.
Also, when the excess solder ball is sucked by the electrostatic suction device,
The electrostatic attraction device can also be operated in a positively charged state and a negatively charged state. Further, it is preferable that the suction jig has a function of sucking a plurality of solder balls by using an air suction force. It is preferable that the electrostatic attraction device is configured to have a flat electrostatic charging surface. In this case, the electrostatic charging surface may have substantially the same area as the suction surface of the solder ball suction jig.

According to the present invention, the excess solder balls are attracted by the electrostatic force, so that the excess solder balls are not applied to the entire solder balls attracted by the suction jig. The ball can be removed. Thus, the surplus solder balls can be removed reliably and in real time.

Further, since the electrostatic attraction device requires only a very simple principle and configuration, it can be obtained at low cost and cost can be reduced.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic explanatory view showing a method for removing excess solder balls according to an embodiment of the present invention, and FIG. 2 is a schematic explanatory view showing a state in which excess solder balls have been removed.

In FIG. 1, reference numeral 10 denotes a solder ball suction jig. A large number of solder balls 11 are suctioned to a suction surface 10a of the suction jig 10 by an air suction force. These solder balls 11 are adsorbed one by one under each of a plurality of intake holes 12 in the illustrated example.
That is, it is adsorbed normally.

On the other hand, the surplus solder balls b are adsorbed in such a manner that they adhere to the normally adsorbed solder balls 11 and hang down due to the attraction force due to the presence of static electricity or the adhesion force due to humidity or the like.

Therefore, in the present embodiment, the electrostatic attraction device 20 is brought close to the surplus solder ball b, and the excess solder ball b is attracted by utilizing the force of attraction of static electricity + and-(see FIG. 2). The removal method is adopted.

The electrostatic attraction device 20 has a flat electrostatic charging surface 21 having substantially the same area as the attraction surface 10a of the attraction jig 10.
For example, a function of applying a relatively high voltage to alternately switch the electrostatic charged surface 21 between a positively charged state and a negatively charged state.

Thus, when the surplus solder ball b is attracted to the electrostatic charging surface 21, the operation of adsorbing in the + charged state and the operation of adsorbing in the -charged state are performed, so that the surplus solder ball b is + − This can be adsorbed regardless of the charging state.

In this electrostatic suction device 20, surplus solder balls b
Here, the force for sucking the solder ball 11 is the solder jig 1
0 is set to be weaker than the suction force by air. By doing so, the solder balls 11 that are normally sucked are not sucked. The setting in this case is
This is a setting in a state where the surplus solder ball b and the electrostatic charging surface 21 are in contact with each other.

Accordingly, when the surplus solder balls b are to be attracted and held with a distance between them, the attraction force of the electrostatic attraction device 20 is set in accordance with the distance. Since the force of attracting the static electricity + and-is inversely proportional to the square of the distance, considering this point, when the distance is large, the force of attracting the surplus solder ball b by the electrostatic attraction device 20 is replaced by the solder ball 11. May be set to be stronger than the suction force of the suction jig 10 by air.

In any case, the force for separating the excess solder ball b attached to the solder ball 11 is set to be weaker than the force for attracting the solder ball 11 by air. There is no particular problem in this regard. This is because the force for attracting the solder balls with air is sufficiently large with respect to the force for attracting the solder balls.

In the illustrated example, for convenience of explanation, an example is shown in which the electrostatic attraction device 20 is brought closer to the surplus solder balls b, but either may be brought closer. Usually, the suction jig 10
Reciprocates between the solder ball container and the circuit board installation position, the electrostatic attraction device 20 may be arranged in the middle of the device and the suction jig 10 may be brought close to the electrostatic attraction device 20.

It is preferable that the approach is made such that the suction surface 10a of the suction jig 10 is located on the lower side as shown in the figure. In this case, there is a method of bringing the adsorption surface 10a and the electrostatic charging surface 21 closer to each other in a straight state as a parallel state body, or a method of bringing them close to each other in a parallel state.

As described above, the excess solder ball b is attracted by the electrostatic attraction device 20 so that an extra external force such as ultrasonic vibration is applied to the solder ball 11 normally attracted to the attraction jig 10. Without adding, only the surplus solder balls b can be removed. At this time, even when the solder ball 11 and the surplus solder ball b are adsorbed by the adhesive force such as humidity, the solder ball 11 can be easily separated and removed.

[0026]

As described above, according to the method of removing the excessively attracted solder balls according to the present invention, the method of removing the excessively attracted solder balls by the attraction jig using the electrostatic force is employed. An excellent effect that surplus solder balls can be reliably and easily removed and that this can be realized by using a simple device is achieved.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing a method for removing surplus adsorbed solder balls according to an embodiment of the present invention.

FIG. 2 is a schematic explanatory view showing a state in which an excessive suction solder ball according to the embodiment of the present invention has been removed.

FIG. 3 is a schematic explanatory view showing a solder bump forming method using a conventional suction jig.

[Description of sign]

 DESCRIPTION OF SYMBOLS 1 Circuit board 2 Predetermined part 3 Solder flag 4 Solder ball 5 Suction jig 6 Through hole 7 Carrier 8 Suction port 9 Cavity 10 Suction jig 10a Suction surface 11 Solder ball 12 Suction hole 20 Electrostatic suction device 21 Electrostatic charging surface

Claims (7)

(57) [Claims] 1. A method of removing a solder ball excessively adsorbed on an adsorption surface of an adsorption jig for a solder ball, wherein the excessively adsorbed solder ball is removed by using an electrostatic adsorption device capable of adsorbing with an electrostatic force. A method for removing surplus adsorbed solder balls. 2. The method according to claim 1, wherein the attraction surface of the attraction jig is located at a lower side, and the electrostatic attraction device is removed by bringing the solder ball excessively attracted to the attraction surface toward the solder ball. 2. The method of claim 1, wherein the excess solder balls are removed. 3. The method according to claim 1, wherein when the excess solder ball is attracted by the electrostatic attraction device, the excess solder ball is attracted with a weaker force than the attraction force of the solder ball by the attraction jig.
The method for removing surplus solder balls according to the description. 4. The method according to claim 1, wherein when the excess solder ball is sucked by the electrostatic suction device, the electrostatic suction device is operated in a positively charged state and a negatively charged state, respectively. 3. The method for removing surplus solder balls according to item 1. 5. The removal of surplus solder balls according to claim 1, wherein the suction jig has a function of sucking a plurality of solder balls by using an air suction force. Method. 6. The method according to claim 1, wherein the electrostatic attraction device has a flat electrostatic charging surface. 7. The method according to claim 6, wherein the electrostatic charging surface has substantially the same area as the suction surface of the solder ball suction jig.