US20150064293A1

US20150064293A1 - Metal ball fabricating apparatus

Info

Publication number: US20150064293A1
Application number: US14/473,406
Authority: US
Inventors: Jeong Tak Moon; Jae Yeol SON; Eung Jae KIM; Su Yong RYU; Hyung Jin Sung; Yong Suk Oh; Hak Song LEE
Original assignee: MK Electron Co Ltd
Current assignee: MK Electron Co Ltd
Priority date: 2013-08-30
Filing date: 2014-08-29
Publication date: 2015-03-05
Also published as: KR101515877B1; KR20150027371A

Abstract

Provided is a metal ball fabricating apparatus for fabricating a metal ball by melting a material. The metal ball fabricating apparatus includes: a fabricating unit configured to fabricate a metal ball; and a collecting unit configured to collect the metal ball. The fabricating unit includes: a chamber configured to receive and store a material; a heating unit configured to apply heat to melt the material in the chamber; an orifice disposed at a lower portion of the chamber to which a metal ball droplet drops; a piston disposed over the orifice to generate a metal ball droplet; and a purifying system configured to remove a foreign substance from the material.

Description

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority under 35 U.S.C. §119 to Korean Patent Application No. 10-2013-0104511, filed on Aug. 30, 2013, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.

FIELD OF THE INVENTION

One or more embodiments relate to metal ball fabricating apparatuses, and more particularly, to a metal ball fabricating apparatus for fabricating a metal ball by melting a material.

BACKGROUND

An orifice having an inner diameter of about 50 μm or less is used to fabricate a micro metal ball having size of about 100 μm, but an oxide of molten solder may block the orifice due to a small inner diameter of the orifice.
In many cases, a purifying operation for purifying a raw material in an alloying process is performed to solve the problem of orifice blockage.
However, since an oxide layer exists on a lumpy surface of a lump of a raw material generated in the alloying process, oxides may be again mixed in the molten solder, at the time of being input into fabrication equipment.
Therefore, there is a need to solve the problem of orifice blockage by incorporating a raw material purifying system, which is used in an alloying process, into a metal ball fabricating apparatus.

SUMMARY

One or more embodiments include metal ball fabricating apparatuses for fabricating metal balls by melting materials.
Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the presented embodiments.
According to one or more embodiments, a metal ball fabricating apparatus for fabricating a metal ball by melting a material includes: a fabricating unit configured to fabricate a metal ball; and a collecting unit configured to collect the metal ball, wherein the fabricating unit includes: a chamber configured to receive and store a material; a heating unit configured to apply heat to melt the material in the chamber; an orifice disposed at a lower portion of the chamber to which a metal ball droplet drops; a piston disposed over the orifice to generate a metal ball droplet; and a purifying system configured to remove a foreign substance from the material.
The purifying system may include a discharge pump configured to discharge a vaporized foreign substance in a heating atmosphere.
The purifying system may include a vacuum pump configured to adjust a vacuum level of the chamber to below about 10⁻¹torr.
The purifying system may include a temperature control unit configured to adjust a heating atmosphere temperature of the chamber in a range of about 500° C. to about 800° C.
The piston and the orifice may be disposed to have a gap of about 0 mm to about 0.5 mm therebetween.
The fabricating unit may include a gap control unit configured to control the gap between the piston and the orifice.
The orifice may include a graphite material.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings in which:

FIG. 1 illustrates an overall structure of a metal ball fabricating apparatus according to an embodiment;

FIG. 2 illustrates a fabricating unit of a metal ball fabricating apparatus according to an embodiment;

FIG. 3 illustrates a graph comparing wettability test results before and after purification is performed by using a purifying system of a metal ball fabricating apparatus according to an embodiment;

FIG. 4 presents a table comparing wettability test results before and after purification is performed by using a purifying system of a metal ball fabricating apparatus according to an embodiment;

FIG. 5 illustrates a state of the material for fabricating a metal ball when the purification temperature is about 300° C. according to an embodiment;

FIG. 6 illustrates a state of the material for fabricating a metal ball when the purification temperature is about 800° C. according to an embodiment;

FIG. 7 illustrates a state of the material when the vacuum level is about 10⁻¹torr according to an embodiment;

FIG. 8 illustrates a state of the material when the vacuum level is about 10⁻³torr according to an embodiment;

FIG. 9 illustrates a comparison of the test dimension and result for each material of the orifice provided in a fabricating unit of a metal ball;

FIG. 10A illustrates a droplet when a metal orifice is used;

FIG. 10B illustrates a droplet when a ceramic orifice is used;

FIG. 10C illustrates a droplet when a graphite orifice is used;

FIG. 11A illustrates a comparison between results when a metal nozzle is used;

FIG. 11B illustrates comparison between results when a ceramic nozzle is used;

FIG. 11C illustrates a comparison between results when a graphite nozzle is used;

FIG. 12 is a table illustrating an overall comparison between results when each of the vacuum level, the purification temperature, and the fabrication temperature is changed; and

FIG. 13 illustrates a graph comparing uniformities of metal ball sizes depending on gaps between a piston and the orifice provided in a fabricating unit of a metal ball fabricating apparatus according to an embodiment.

FIG. 14 presents a table comparing uniformities of metal ball sizes depending on gaps between a piston and the orifice provided in a fabricating unit of a metal ball fabricating apparatus according to an embodiment.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. In this regard, the present embodiments may have different forms and should not be construed as being limited to the descriptions set forth herein. Accordingly, the embodiments are merely described below, by referring to the figures, to explain aspects of the present description. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.
Exemplary embodiments will now be described in detail with reference to the accompanying drawings. However, these embodiments are not limited thereto.
The effects and features of the embodiments and the accomplishing method thereof will become apparent from the following description of the embodiments, taken in conjunction with the accompanying drawings. The invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein; rather, these embodiments are provided such that this disclosure will be thorough and complete, and will fully convey the concept of the invention to one of ordinary skill in the art.
Spatially relative terms, such as “above,” “upper,” “beneath,” “below,” “lower,” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the drawings. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation illustrated in the drawings. For example, if the device in the drawings is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the exemplary term “above” may encompass both an orientation of above and below. The device may be otherwise oriented (rotated about 90 degrees or at other orientations) and the spatially relative descriptors used herein may be interpreted accordingly.
The terminology used herein is for the purpose of describing the embodiments only and is not intended to be limiting of the embodiments. As used herein, the singular forms “a,” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprise” and “comprising” used herein specify the presence of stated elements, steps, operations, and/or devices, but do not preclude the presence or addition of one or more other elements, steps, operations, and/or devices.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the embodiments belong. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
FIG. 1 illustrates an overall structure of a metal ball fabricating apparatus 1 according to an embodiment. FIG. 2 illustrates a fabricating unit 10 of the metal ball fabricating apparatus 1 according to an embodiment. FIGS. 3 and 4 illustrate a comparison between wettability test results before and after purification is performed by using a purifying system 30 of the metal ball fabricating apparatus 1 according to an embodiment. FIGS. 5 and 6 illustrate a comparison between results when purification is performed under different purification temperatures by using the purifying system 30 of the metal ball fabricating apparatus 1 according to an embodiment. FIGS. 7 and 8 illustrate a comparison between results when purification is performed under different vacuum levels by using the purifying system 30 of the metal ball fabricating apparatus 1 according to an embodiment. FIGS. 9 to 11 illustrate a comparison between results when an orifice 150 provided in the fabricating unit 10 of the metal ball fabricating apparatus 1 according to an embodiment is formed of different materials. FIG. 12 is a table illustrating an overall comparison between results when each of the vacuum level, the purification temperature, and the fabrication temperature is changed. FIGS. 13 and 14 illustrate a comparison between uniformities of metal ball (S) sizes depending on gaps between a piston 130 and the orifice 150 provided in the fabricating unit 10 of the metal ball fabricating apparatus 1 according to an embodiment.
The metal ball fabricating apparatus 1 according to an embodiment is a metal ball fabricating apparatus 1 for fabricating a metal ball S by melting a material. The metal ball fabricating apparatus 1 includes: a fabricating unit 10 configured to fabricate a metal ball S; and a collecting unit 20 configured to collect the metal ball S. The fabricating unit 10 includes: a chamber 110 configured to receive and store a material; a heating unit 120 configured to apply heat to melt the material in the chamber 110; an orifice 150 disposed at a lower portion of the chamber 110 to which a metal ball (S) droplet drops; a piston 130 disposed over the orifice 150 to generate a metal ball (S) droplet; and a purifying system 30 configured to remove a foreign substance from the material.
The metal ball fabricating apparatus 1 is configured to include the fabricating unit 10 and the collecting unit 20.
The fabricating unit 10 includes various devices configured to receive a material, which is a raw material of the metal ball S, and fabricate the metal ball S, and substantially constitutes a body of the metal ball fabricating apparatus 1. The metal ball S may be a metal ball S used in a wire bonding package and may be spherical; however, embodiments are not limited thereto.
The material used to fabricate the metal ball may be, for example, an alloy including various metals such as copper (Cu), nickel (Ni), aluminum (Al), and cobalt (Co), and a chemical additive may be added thereto; however, embodiments are not limited thereto.
The material is stored in the chamber 110. In one embodiment, the chamber 110 is configured to have a predetermined strength to endure a high temperature and a high pressure difference, and has an appropriate capacity.
The heating unit 120 is provided to heat the material in the chamber 110. The heating unit 120 may heat the chamber 110 by, for example, an electrical resistance to melt the material in the chamber 110, but its configuration and shape are not limited thereto.
The orifice 150 is provided at a lower portion of the chamber 110 so that the material in the chamber 110 may be heated and melted and the melted material may drop in the shape of droplets. The orifice 150 has the shape of a minute pipe and has an appropriate shape and configuration for forming a metal ball (S) droplet of a desired size and controlling the metal ball (S) droplet. Since the orifice 150 may be damaged when the melted metal ball (S) droplet drops, the orifice 150 may be attached/detached to/from the chamber 110 so that the orifice 150 may be replaced when necessary; however, embodiments are not limited thereto. The orifice 150 may be configured to include a graphite material.
The piston 130 is disposed over the orifice 150. The piston 130 is spaced apart from the orifice 150 by a predetermined gap and is configured to perform a piston movement so that the melted material forms the metal ball (S) droplet. Accordingly, the piston 130 may be configured to perform a vertical piston movement, and the gap between the piston 130 and the orifice 150 and the movement period of the piston 130 may be adjusted appropriately. A power applying unit 140 may be provided so that the piston 130 may perform a piston movement.
The purifying system 30 is provided to remove a foreign substance from the material stored in the chamber 110. The purifying system 30 may include a device constituting a portion of the fabricating unit 10 of the metal ball fabricating apparatus 1. The purifying system 30 may be any member or device that may serve to remove a foreign substance from the material. It may also be understood that, when the purifying system 30 constitutes a portion of the fabricating unit 10, the purifying system 30 may be incorporated into the fabricating unit 10 to remove a foreign substance from the material in a fabrication process. The purifying system 30 will be described later.
In addition to the above-described units or members, an inert gas injecting unit 160, various pipe structures, and valve units 162 and 172 may be provided to supply an inert gas to maintain an atmosphere suitable for fabricating the metal ball S; however, embodiments are not limited thereto.
The collecting unit 20 is provided to collect the metal ball S fabricated by the fabricating unit 10. The collecting unit 20 may include a collecting valve 24, a collecting chamber 26, and a cooling chamber 22 configured such that the metal ball (S) droplet dropping through the orifice 150 may be cooled and solidified in a dropping process.
The cooling chamber 22 may be extended with a vertical height such that the metal ball (S) droplet may be cooled in the dropping process.
The collecting chamber 24 is a member for collecting the dropped metal ball (S). A sieve may be provided in the collecting chamber 24 to load the metal ball S. The sieve may be extracted by a transport unit to discharge the metal ball S to outside.
The collecting unit 20 may include various transport devices for collecting the metal ball S and a valve serving to collect the metal ball S, and the configuration of the collecting unit 20 is not limited thereto.
Hereinafter, the purifying system 30 will be described in detail.
The purifying system 30 may include any device that is used to remove a foreign substance from the material and may also include any device that may serve to remove a foreign substance from the material.
For example, when the material is heated to a predetermined temperature to remove the foreign substance, the heating unit 120 heating the material may serve to remove the foreign substance, but the heating unit 120 may also be used to melt the material that is used to fabricate the metal ball S. As another example, a gas injecting unit and a pump serving to discharge a vaporized foreign substance may serve to remove the foreign substance and constitute a portion of the purifying system 30. However, since the gas injecting unit and the pump may also serve to adjust an atmosphere in the chamber 110, melt the material, and fabricate the metal ball S, they may also be included in a component other than the purifying system 30.
Thus, according to some embodiments, the purifying system 30 should not be regarded as a separate device that is independent of other members or devices in the fabricating unit 10, and may be regarded as a portion constituting the fabricating unit 10.
The purifying system 30 includes a discharge pump 170 configured to discharge the foreign substance in a heating atmosphere.
When the chamber 110 is heated in a predetermined atmosphere to a temperature that is equal to or higher than a melting temperature, the material in the chamber 110 is melted into liquid. In this case, oxygen and a foreign substance, such as various oxides, which are contained in the liquid material, may be floated on a surface thereof, and the foreign substance may be removed by the operation of the discharge pump 170.
In this case, the atmosphere in the chamber 110 may be a near-vacuum atmosphere, and the discharge pump 170 may include a vacuum pump. By the operation of the discharge pump 170, air in the chamber 110 may flow toward the vacuum pump to be discharged to outside, and a relatively light foreign substance such as the oxide may be discharged according to the air flow. In this case, the vacuum level of the chamber 110 may be low and may be adjusted to about 2.0×10⁻²torr or less.
The purifying system 30 may include a temperature control unit (not illustrated) configured to adjust a heating atmosphere temperature of the chamber 110 in a range of about 500° C. to about 900° C.
The temperature control unit may control the operation of the heating unit 120 and adjust the temperature of the chamber 110 so that the foreign substance may be easily separated while the material is easily melted. In this case, the temperature control unit may control the temperature of the chamber 110 from about 500° C. to about 900° C., for example, or to about 800° C. Accordingly, the temperature control unit may include a temperature sensor and a control unit controlling the operation of the heating unit 120.
As described above, according to the one or more of the above embodiments, since the purifying system 30 is included in the fabricating unit 10, the metal ball fabricating apparatus 1 may fabricate the metal ball S by a pure material alone by removing a foreign substance from the material used to fabricate the metal ball S. Also, since a material purifying operation is performed in a melting process for fabrication, a separate independent purifying unit may not be necessary and the purified material may be prevented from being contaminated again by being exposed to outside when supplied into the chamber 110.
Thus, the higher-quality metal ball S may be fabricated, and the efficiency of the fabrication process may be improved and the fabrication cost may be reduced, since the blockage of the orifice 150, to which the metal ball (S) droplet drops, is prevented.
In one embodiment, the piston 130 and the orifice 150 are disposed to have a gap of about 0 mm to about 0.5 mm therebetween.
The piston 130 is spaced apart from the orifice 150 by a predetermined gap and performs a piston movement so that the melted material may drop in the form of droplets through the orifice 150. In this case, in order to form a metal ball (S) droplet of a desired size, the piston 130 and the orifice 150 may have a gap therebetween and the gap between the piston 130 and the orifice 150 may be adjusted to about 0 mm to about 0.5 mm. Herein, the gap between the piston 130 and the orifice 150 represents a gap at which the piston 130 is advanced to maximum and is most adjacent to the orifice 150.
A gap control unit 142 may be provided to adjust the gap between the piston 130 and the orifice 150.
The gap control unit 142 may be provided to adjust the gap between the piston 130 and the orifice 150, and may be, for example, a device that changes the initial position of the piston 130. By the gap control unit 142, the gap between the piston 130 and the orifice 150 may be changed and the size of the metal ball (S) droplet may also be changed appropriately. Thus, the metal balls S of various sizes may be fabricated according to purposes, and the general purpose of the metal ball fabricating apparatus 1 may be improved.
Hereinafter, the effects of the metal ball fabricating apparatus 1 according to an embodiment will be described with reference to the drawings.
FIGS. 3 and 4 illustrate a comparison between wettability test results before and after purification is performed by using the purifying system 30 of the metal ball fabricating apparatus 1 according to an embodiment.
It may be seen from FIGS. 3 and 4 that a wetting force is increased and a zero-cross time is reduced after the purification is performed.
That is, the zero-cross time is the time taken to balance the water level of solder, and the zero-cross time may be short as much as possible. In one embodiment, in order to reduce the zero-cross time, the surface tension should be low. In general, as the amount of interposer in a melted metal increases, the surface tension increases and thus the zero-cross time increases.
According to some embodiments, the zero-cross time is reduced after the purification, and this may be regarded as the improvement of a fluid flow. Thus, it may be seen that the fluidity of the melted material passing through the hole of the orifice is improved by the purification of the material.
Also, as the surface tension decreases, the wetting force increases. As seen from FIG. 4, the increase of the wetting force after purification represents the decrease of the surface tension, and this represents the improvement of the fluidity of the material.
FIGS. 5 and 6 illustrate a comparison between results when purification is performed under different purification temperatures by using the purifying system 30 of the metal ball fabricating apparatus 1 according to an embodiment. FIGS. 7 and 8 illustrate a comparison between results when purification is performed under different vacuum levels by using the purifying system 30 of the metal ball fabricating apparatus 1 according to an embodiment.
FIG. 5 illustrates a state of the material when the purification temperature is about 300° C., and FIG. 6 illustrates a state of the material when the purification temperature is about 800° C. It may be seen that the oxide layer formed on the surface of the material may be further reduced in the case where the purification temperature is about 800° C., in comparison with the case where the purification temperature is about 300° C.
FIG. 7 illustrates a state of the material when the vacuum level is about 10⁻¹torr, and FIG. 8 illustrates a state of the material when the vacuum level is about 10⁻³torr. It may be seen that the oxide layer formed on the surface of the material may be further reduced in the case where the vacuum level is about 10⁻³torr, in comparison with the case where the vacuum level is about 10⁻¹torr.
As described above, it may be seen that the purification of the material is further improved by the removal of the oxide when the material is melted while the high temperature and the low vacuum level are maintained.
FIGS. 9 to 11 illustrate a comparison between results when the orifice 150 provided in the fabricating unit 10 of the metal ball fabricating apparatus 1 according to an embodiment is formed of different materials.
FIG. 9 illustrates the test dimension and result for each material of the orifice 150, FIG. 10 illustrates each orifice 150, and FIG. 11 illustrates the uniformity of droplets generated through each orifice 150.
FIG. 10A illustrates a droplet when a metal orifice 150 is used, FIG. 10B illustrates a droplet when a ceramic orifice 150 is used, and FIG. 10C illustrates a droplet when a graphite orifice 150 is used.
It may be seen from FIGS. 9 to 11 that, when the orifice 150 is formed of graphite having excellent slippage characteristics, most stable and uniform droplets are formed even when a small orifice 150 is used.
FIG. 12 is a table illustrating an overall comparison between results when the vacuum level, the purification temperature, and the fabrication temperature are changed. It may be seen from FIG. 12 that the fabrication result is varied when each of the vacuum level, the purification temperature, and the fabrication temperature is changed.
FIGS. 13 and 14 illustrate a comparison between uniformities of metal ball (S) sizes depending on gaps between the piston 130 and the orifice 150 provided in the fabricating unit 10 of the metal ball fabricating apparatus 1 according to an embodiment.
As illustrated in FIGS. 13 and 14, it may be seen that the size of the fabricated metal ball S and the deviation of the size increase as the gap between the piston 130 and the orifice 150 increases in the piston movement having the same frequency.
As described above, since the gap control unit 142 is provided to adjust the gap between the piston 130 and the orifice 150, the gap between the piston 130 and the orifice 150 may be adjusted, and the piston 130 and the orifice 150 may be adjusted to have an optimum gap therebetween in the fabrication process. Therefore, the metal balls S may be fabricated to have a uniform size.
As described above, according to the one or more of the above embodiments, since the purifying system 30 is included the fabricating unit 10, the metal ball fabricating apparatus 1 may fabricate the metal ball S by a pure material alone by removing a foreign substance from the material used to fabricate the metal ball S. Also, since a material purifying operation is performed in a melting process for fabrication, a separate independent purifying unit may not be necessary and the purified material may be prevented from being contaminated again by being exposed to outside when supplied into the chamber 110.
Thus, the higher-quality metal ball S may be fabricated, and the efficiency of the fabrication process may be improved and the fabrication cost may be reduced, since the blockage of the orifice 150, to which the metal ball (S) droplet drops, is prevented.
Also, since the gap control unit is provided to adjust the gap between the piston 130 and the orifice 150, the gap between the piston 130 and the orifice 150 may be changed and the size of the metal ball (S) droplet may also be changed appropriately. Thus, the metal balls S of various sizes may be fabricated according to purposes, and the general purpose of the metal ball fabricating apparatus 1 may be improved.
Also, even when a small orifice including a graphite material is used, stable and uniform metal ball droplets may be formed.
It should be understood that the exemplary embodiments described herein should be considered in a descriptive sense only and not for purposes of limitation. Descriptions of features or aspects within each embodiment should typically be considered as available for other similar features or aspects in other embodiments.
While one or more embodiments have been described with reference to the figures, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope as defined by the following claims.

Claims

What is claimed is:

1. A metal ball fabricating apparatus for fabricating a metal ball by melting a material, the metal ball fabricating apparatus comprising:

a fabricating unit configured to fabricate a metal ball; and

a collecting unit configured to collect the metal ball,

wherein the fabricating unit comprises:

a chamber configured to receive and store a material;

a heating unit configured to apply heat to melt the material in the chamber;

an orifice disposed at a lower portion of the chamber to which a metal ball droplet drops;

a piston disposed over the orifice to generate a metal ball droplet; and

a purifying system configured to remove a foreign substance from the material.

2. The metal ball fabricating apparatus of claim 1, wherein the purifying system comprises a discharge pump configured to discharge a vaporized foreign substance in a heating atmosphere.

3. The metal ball fabricating apparatus of claim 1, wherein the purifying system comprises a vacuum pump configured to adjust a vacuum level of the chamber to below about 10⁻¹torr.

4. The metal ball fabricating apparatus of claim 1, wherein the purifying system comprises a temperature control unit configured to adjust a heating atmosphere temperature of the chamber in a range of about 500° C. to about 800° C.

5. The metal ball fabricating apparatus of claim 1, wherein the piston and the orifice are disposed to have a gap of about 0 mm to about 0.5 mm therebetween.

6. The metal ball fabricating apparatus of claim 5, wherein the fabricating unit comprises a gap control unit configured to control the gap between the piston and the orifice.

7. The metal ball fabricating apparatus of claim 1, wherein the orifice comprises a graphite material.