JP2008261057A - Method for producing spherical body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a means capable of easily producing a spherical body such as a solder ball with reduced stages at a low cost. <P>SOLUTION: The raw material of a spherical body is discharged from a discharge port in the state of a melt, at the point of the time in which the discharge amount reaches the desired one, the melt is separated at the discharge port by the flow of a fluid, and the separated raw material of a spherical body is made sphere by surface tension in the state of the melt and is thereafter solidified. Since the raw material of the spherical body discharged from the discharge port can be easily separated in the state of the melt by the flow of the fluid and can be separated into a desired amount in the state of the melt, a stage of working the raw material such as solder into a sheet material or a wire rod performed in the conventional method is made needless, thus the reduction of the production process can be attained. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method and an apparatus for manufacturing a spherical body such as a solder ball used for a bump material of a semiconductor package such as a BGA (ball grid array) and a CSP (chip size package).

  For example, in the field of semiconductor packages, a so-called BGA in which solder balls (solder bumps) are mounted instead of leads for electrical connection to a built-in semiconductor chip is known. When manufacturing solder balls used in such BGAs, conventionally, solder processed into a plate material or wire material such as foil is precisely cut out or punched in a solid state, thereby converting the solder into a desired amount of raw material pieces. After separation, the raw material pieces are heated and melted to be spheroidized by surface tension, and further cooled and solidified to obtain solder balls molded into a spherical shape. Also, solder paste (cream solder) is created and a certain amount of solder is separated by methods such as screen printing or printing on a plate with a certain volume of holes, and then the solder is heated and melted to make it spherical by surface tension. The method of making it known is also known.

  However, conventionally, as a pre-process for separating the solder into a desired amount, it has been necessary to process the solder into a plate material, a wire, a solder paste, or the like, and it has been difficult to shorten the manufacturing process. Moreover, in order to accurately measure the solder, accurate dimensional accuracy is required for the thickness of the plate material and the thickness of the wire formed in the previous process, which causes an increase in costs in the manufacture of solder balls. It was. Today, there is no major dissatisfaction with respect to the solder ball, but rather a full-fledged popularization period of BGA, CSP, etc., and there is a need for a solder ball that can be greatly reduced in cost. For this purpose, it is necessary to establish means capable of producing solder balls with fewer steps than in the past.

  Accordingly, an object of the present invention is to provide a means capable of manufacturing a spherical body such as a solder ball easily and at low cost with few steps.

  In order to achieve this object, according to the first aspect, the spherical material is discharged from the discharge port in the melt state, and when the discharge amount reaches a desired amount, the flow of the fluid causes the discharge port to There is provided a method for producing a spherical body, characterized in that the melt is separated, and the separated spherical raw material is made spherical by surface tension in the melt state and then solidified.

  Examples of the spherical body manufactured by the manufacturing method of claim 1 include a spherical body such as a solder ball used for a bump material of a semiconductor package such as BGA or CSP. Further, as described in claim 4, the spherical material is, for example, a metal, and an example thereof is solder (for example, Sn—Pb eutectic solder). In addition to solder, as described in claim 5, the raw material of the spherical body is a single metal having a liquidus temperature of 450 ° C. or lower (may be 450 ° C. or higher) or two or more types as described in claim 5. An alloy made of any of these metals may be used. Furthermore, it is also possible to use a material other than metal as a raw material for the spherical body.

  According to the manufacturing method of the first aspect, since the spherical raw material discharged from the discharge port can be easily separated into a desired amount in the melt state by the flow of the fluid in the melt state, A process of processing a raw material such as solder into a plate material or a wire becomes unnecessary, and the manufacturing process can be shortened. In addition, since it is not necessary to process the raw material into a plate material or a wire material that requires accurate dimensional accuracy or the like, manufacturing becomes easy and cost reduction can be realized.

  According to a second aspect of the present invention, the fluid flow may be constant, or may change periodically or in a pulse manner. By shaking off the melt from the nozzle tip by such a fluid flow, it is possible to separate the spherical raw material into a desired amount in the melt state. The spherical material may be continuously discharged from the nozzle in the melt state, or may be intermittently discharged from the nozzle in the melt state.

  In addition, as described in claim 3, the fluid is preferably a gas or a liquid that does not react with the melt. By doing so, it becomes possible to separate the spherical raw materials without altering them. Even when the separated spherical raw material is made spherical by surface tension in the melt state, or when it is cooled and solidified thereafter, it is preferably carried out in an atmosphere that does not alter the spherical raw material.

  According to a seventh aspect of the present invention, a spherical body is produced, comprising: a raw material nozzle that discharges the raw material of the spherical body in a melt state; and a fluid nozzle that supplies fluid to the raw material nozzle from the side. An apparatus is provided.

  In the manufacturing apparatus according to claim 7, by supplying a fluid from the side by the raw material nozzle to the spherical raw material discharged from the raw material nozzle, the desired amount can be easily obtained in the melt state. Can be separated. The spherical raw material thus separated is first transformed into a spherical shape by surface tension in the melt state. Thereafter, the spherical material can be easily manufactured by cooling and solidifying the spherical material.

  According to the first to seventh aspects, since the spherical raw material can be easily separated by the flow of fluid in the melt state and is separated into a desired amount in the melt state, the raw material such as solder as in the prior art The process of processing the sheet into a plate or wire becomes unnecessary, and the manufacturing process can be shortened. In addition, since it is not necessary to process the raw material into a plate material or a wire material that requires accurate dimensional accuracy or the like, manufacturing becomes easy and cost reduction can be realized.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram of a spherical body manufacturing apparatus 1 according to an embodiment of the present invention. In this embodiment, a manufacturing apparatus 1 for manufacturing a solder ball a used as a bump material of a semiconductor package such as BGA or CSP will be described as an example of a spherical body.

  The upper half of the apparatus main body 10 is a molding part 11, and the lower half is a cooling part 12. The inside of the apparatus main body 10 is filled with silicone oil that is a fluid that does not react with solder. Band heaters 13 and 14 are vertically mounted on the peripheral surface of the apparatus main body 10, and silicone oil filled in the apparatus main body 10 is controlled by arbitrarily controlling the heating temperature of each of the band heaters 13 and 14. It is possible to form a temperature gradient therein. The heating temperature of the upper band heater 13 is set to be higher than the heating temperature of the lower band heater 14, so that the silicone oil is at a temperature higher than the melting point of the solder in the upper molding portion 11 in the apparatus body 10. (For example, 190 to 200 ° C.). On the other hand, since the heating temperature of the band heater 14 is low in the cooling unit 12 below the apparatus main body 10, the silicone oil is kept at a temperature below the melting point of the solder (for example, 160 to 170 ° C.) in the molding unit 11. Yes. As described above, a gradual temperature gradient is formed in the silicone oil filled in the apparatus main body 10 so that the upper side is a high temperature not lower than the melting point of the solder and the lower side is a low temperature not higher than the melting point of the solder. ing.

  The molding unit 11 in the upper part of the apparatus main body 10 includes a melt container 20 filled with melted solder and a fluid container 21 filled with silicone oil as a fluid for separating the melt (solder). is set up. Since the melt container 20 and the fluid container 21 are in the molding part 11 maintained at a temperature equal to or higher than the melting point of the solder, the solder filled in the melt container 20 maintains the melt state. The silicone oil filled in the fluid container 21 is also maintained at a temperature higher than the melting point of the solder. The melt container 20 and the fluid container 21 are made of, for example, SUS304 or the like, and do not melt even if heated above the melting point of the solder.

  A gas pipe 22 is connected to the upper surface of the melt container 20, and nitrogen gas as an inert gas is supplied into the melt container 20 through the gas pipe 22 from a gas cylinder 23 installed outside the apparatus body 10. By doing so, it is possible to pressurize the inside of the melt container 20. Similarly, a gas pipe 25 is connected to the upper surface of the fluid container 21, and argon gas as an inert gas is supplied from the gas cylinder 26 installed outside the apparatus body 10 through the gas pipe 25 into the fluid container 21. It is possible to pressurize the inside of the fluid container 21 by supplying to the inside.

  A melt pipe 27 is connected to the bottom surface of the melt container 20, and the tip of the melt pipe 27 is formed in the raw material nozzle 28. Then, as described above, an inert gas (nitrogen gas) is supplied from the gas cylinder 23 into the melt container 20 through the gas pipe 22 and pressurized, so that the spherical body filled in the melt container 20 is formed. Solder as a raw material can be fed through the melt pipe 27 and discharged from the raw material nozzle 28 in the form of a melt.

  Similarly, a fluid pipe 29 is connected to the bottom surface of the fluid container 21, and the tip of the fluid pipe 29 is formed in the fluid nozzle 30. Then, as described above, the inert gas (argon gas) is supplied from the gas cylinder 26 into the fluid container 21 through the gas pipe 25 and pressurized, so that the silicone oil filled in the fluid container 21 is fluidized. It is possible to send the liquid through the pipe 29 and discharge it from the fluid nozzle 30. Although not shown, the gas pipe 25 is provided with a valve for adjusting the gas pressure so that the discharge amount of the silicone oil discharged from the fluid nozzle 30 is constant or a constant amount every predetermined time. It is also possible to periodically change the amount of silicone oil discharged from the fluid nozzle 30 such as discharging silicone oil. Although not shown in the drawings, the apparatus main body 10 includes a leak mechanism for discharging the silicone oil corresponding to the discharge amount of the silicone oil discharged from the fluid nozzle 30 to the outside of the apparatus main body 10. High pressure is prevented.

  A support block 32 for fixing the melt pipe 27 and the fluid pipe 29 is provided in the molding portion 11 in the upper part of the apparatus main body 10. The melt pipe 27, the fluid pipe 29, the raw material nozzle 28, and the fluid nozzle 30 that are supported by the support block 32 are all arranged in the molding part 11 in the upper part of the apparatus main body 10.

  FIG. 2 is an enlarged view showing the positional relationship between the raw material nozzle 28 and the fluid nozzle 30. By being supported by the support block 32 as described above, in this embodiment, the raw material nozzle 28 is disposed in the horizontal direction, and the fluid nozzle 30 is disposed in the downward direction in the vertical direction. Thus, the raw material nozzle 28 and the fluid nozzle 30 are arranged so as to be orthogonal to each other, and the positional relationship in which the fluid nozzle 30 supplies silicone oil from the side (upper in the illustrated example) with respect to the discharge port 33 at the tip of the raw material nozzle 28. It is configured.

  Then, as described above, when the inert gas is supplied from the gas cylinder 23 and the inside of the melt container 20 is pressurized, the solder a ′ as a spherical material is discharged from the material nozzle 28 in a melt state. . The solder a ′ thus discharged adheres to the discharge port 33 at the tip of the raw material nozzle 28 in the form of a melt, and droplets of the solder (melt) a ′ are formed. On the other hand, as described above, when the inert gas is supplied from the gas cylinder 26 and the inside of the fluid container 21 is pressurized, silicone oil is discharged from the fluid nozzle 30. Thereby, as shown in FIG. 2, when the discharge amount of the solder (melt) a ′ discharged from the raw material nozzle 28 reaches a desired amount, the raw material is flown by the flow of the silicone oil discharged from the fluid nozzle 30. The solder (melt) a ′ is cut off and separated from the discharge port 33 at the tip of the nozzle 28, and the separated solder (melt) a ′ falls by its own weight in the silicone oil filled in the apparatus main body 10. It is like that.

  By being supported by the support block 32 described above, the melt pipe 27, the fluid pipe 29, the raw material nozzle 28, and the fluid nozzle 30 are all maintained at a temperature equal to or higher than the melting point of the solder. Therefore, while being fed from the melt pipe 27 to the raw material nozzle 28, when being discharged in the melt state from the raw material nozzle 28, and while being fed from the fluid pipe 29 to the fluid nozzle 30 Even when discharged from the fluid nozzle 30, the solder and silicone oil are kept at a temperature equal to or higher than the melting point of the solder. As described with reference to FIG. 2, the solder (melt) a ′ separated from the discharge port 33 at the tip of the raw material nozzle 28 by the flow of the silicone oil discharged from the fluid nozzle 30 is separated in the upper part of the apparatus main body 10. While the molding part 11 is being dropped, the temperature is maintained at a temperature equal to or higher than the melting point of the solder, thereby maintaining the melt state. Then, by dropping while maintaining the state of the melt in this way, the solder (melt) a ′ is molded into a spherical shape by the surface tension while dropping the molding portion 11 in the upper part of the apparatus main body 10. It is like that.

  Both the melt pipe 27 and the fluid pipe 29 are made of, for example, SUS304 or the like, and do not melt even if heated to a melting point of solder or higher. In this embodiment, the melt pipe 27 is composed of a thin tube (inner diameter 0.25 mm) made of SUS316.

  On the other hand, the solder (melt) a ′ cut and separated from the discharge port 33 at the tip of the raw material nozzle 28 passes through the molding part 11 in the upper part of the apparatus body 10 and then the cooling part in the lower part of the apparatus body 10. 12 is falling. As described above, in the cooling unit 12 below the apparatus main body 10, the silicone oil filled in the apparatus main body 10 is maintained at a temperature below the melting point of the solder (for example, 20 to 40 ° C.). In this way, when passing through the cooling unit 12, the solder (melt) a ′ is cooled to a temperature below the melting point of the solder. As a result, the solder (melt) a ′ is cooled and solidified while falling in the cooling section 12 below the apparatus main body 10.

  Now, in the manufacturing apparatus 1 according to the embodiment of the present invention configured as described above, an inert gas is supplied from the gas cylinder 23 and the inside of the melt vessel 20 is pressurized, whereby the solder a as a raw material for the spherical body is obtained. 'Is discharged from the raw material nozzle 28 in a melt state. The solder a 'thus discharged adheres to the discharge port 33 at the tip of the raw material nozzle 28, and droplets of the solder (melt) a' are formed. On the other hand, an inert gas is supplied from the gas cylinder 26 and the inside of the fluid container 21 is pressurized to discharge silicone oil from the fluid nozzle 30. Thus, as described above with reference to FIG. 2, when the discharge amount of the solder (melt) a ′ discharged from the raw material nozzle 28 reaches a desired amount, the silicone oil discharged from the fluid nozzle 30 is discharged. The solder (melt) a ′ is separated and separated from the discharge port 33 at the tip of the raw material nozzle 28 by the flow. The separated solder (melt) a ′ falls in the silicone oil by its own weight in the apparatus main body 10.

  Thus, the solder (melt) a ′ separated and falling from the discharge port 33 at the tip of the raw material nozzle 28 first passes through the molding part 11 in the upper part of the apparatus main body 10, and then the cooling part in the lower part of the apparatus main body 10. Pass through 12 The solder (melt) a ′ is maintained in the melt state while dropping the molding portion 11 in the upper part of the apparatus main body 10 maintained at a temperature equal to or higher than the melting point of the solder, and is spherical due to the surface tension. Transforms into Then, the solder (melt) a ′ thus deformed into a spherical shape then drops down the cooling unit 12 in the lower part of the apparatus main body 10, but the heating temperature of the band heater 14 is low in the cooling unit 12, Since the temperature is lower than the melting point of the solder (for example, 160 to 170 ° C.), the solder (melt) a ′ is cooled and solidified while the cooling unit 12 is dropped. In this way, the solder ball a that is a spherical body is manufactured and accumulated at the bottom of the apparatus main body 10. In this case, a gradual temperature gradient is formed in the silicone oil filled in the apparatus main body 10 so that the upper side is a high temperature not lower than the melting point of the solder and the lower side is a low temperature not higher than the melting point of the solder. Therefore, the solder (melt) a ′ falling from the molding part 11 to the cooling part 12 is gradually cooled without being subjected to a rapid temperature change, so that a shape defect or the like due to a sudden change in temperature occurs. Disappear.

  According to the embodiment of the present invention described above, a desired amount of solder (melt) a ′ discharged from the raw material nozzle 28 in the melt state by the flow of silicone oil discharged from the fluid nozzle 30. Since they can be separated, a process for processing the raw material into a plate material or a wire is not required as in the prior art, and the manufacturing process of the solder balls a can be shortened. In addition, since it is not necessary to process the raw material into a plate material or wire that requires accurate dimensional accuracy, the solder ball a can be easily manufactured, and cost reduction can be realized. The size of the solder ball a to be manufactured is determined by changing the supply pressure of the inert gas from the gas cylinder 23 or the gas cylinder 6 and supplying the amount of solder (melt) a ′ to the melt pipe 27 or the fluid pipe 29. It can be adjusted by appropriately changing the amount of the silicone oil fed to the liquid. Further, the size of the solder ball a may be adjusted by making the discharge amount of the silicone oil discharged from the fluid nozzle 30 constant or by periodically changing the discharge amount of the silicone oil discharged from the fluid nozzle 30. Is possible.

  As mentioned above, although an example of preferable embodiment of this invention was demonstrated, this invention is not limited to the form demonstrated here. For example, the tip of the raw material nozzle 28 may be a pipe-shaped discharge port 33 having a constant inner diameter as shown in FIG. 3, but as shown in FIGS. It is good also as the taper-shaped discharge port 33 which becomes narrow. In order to easily separate the solder (melt) a ′ from the discharge port 33 at the tip of the raw material nozzle 28, it is preferable to make the inner surface of the raw material nozzle 28 have a taper angle as large as possible as shown in FIG.

  In the illustrated embodiment, the example in which the raw material nozzles 28 are arranged in the horizontal direction and the fluid nozzles 30 are arranged in the vertical direction has been described. However, for example, the raw material nozzles 28 are arranged in the vertical direction and the fluid nozzles 30 are arranged in the horizontal direction. You may arrange in. Further, the raw material nozzle 28 and the fluid nozzle 30 do not necessarily have to be arranged orthogonally. In any case, it suffices that the droplets of the solder (melt) a ′ adhering to the discharge port 33 at the tip of the raw material nozzle 28 can be separated and separated by the flow of the silicone oil discharged from the fluid nozzle 30. In order to easily separate the droplets of the solder (melt) a ′ from the discharge port 33, it is preferable that the wettability between the raw material nozzle 28 and the solder (melt) a ′ is low. It should be composed of stainless steel.

  In the above embodiment, an example in which a solder ball is manufactured as an example of a spherical body has been described. However, a raw material for the spherical body may be a metal other than solder or a material other than metal. Further, the fluid discharged from the fluid nozzle 30 is not limited to silicone oil, but may be other liquids or gases. Further, a plurality of discharge ports may be arranged in the fluid flow, and by separating the spherical material from the plurality of discharge ports in a melt state, more solder balls can be obtained in a short time. It can be manufactured.

Solder balls were manufactured by actually using the manufacturing apparatus 1 according to the embodiment of the present invention described with reference to FIG. Sn-37Pb solder was used as a spherical material. As the fluid, silicone oil (TSF458-100 manufactured by Toshiba Silicone Co., Ltd.) was used. A thin tube made of SUS316 (inner diameter 0.25 mm, straight tube) was placed in the flow of silicone oil discharged from the fluid nozzle, and the silicone oil was supplied so as to be orthogonal to the tip of the thin tube. The piping system was replaced with nitrogen by nitrogen gas supplied from a nitrogen gas cylinder. Next, after filling the fluid container with silicone oil, immerse the fluid container, melt container, each pipe and support block in the apparatus body filled with silicone oil, and heat with each band heater attached to the apparatus body, In the silicone oil filled in the device body, a gentle temperature gradient so that the upper part (molded part) has a high temperature above the melting point of the solder and the lower part (cooling part) has a low temperature below the melting point of the solder. Form. After confirming that the temperature of the silicone oil in the fluid container and the solder (melt) in the melt container is 195 to 210 ° C., pressurize with a predetermined pressure from each gas cylinder, and solder ( (Melt) was fed at 5.0 g / min, and the silicone oil in the fluid container was fed at 49 cm / sec. In this way, the solder (melt) discharged from the raw material nozzle is separated in a desired amount by the flow of silicone oil, and the separated solder (melt) is dropped in the silicone oil by its own weight, and the surface of the molding part Solder (melt) deformed into a spherical shape by tension was cooled and solidified in the cooling section. FIG. 6 is a sketch of an SEM photograph showing the appearance of the solder ball obtained in Example 1. When the particle diameter was evaluated from the photographic magnification, the solder ball diameter was 0.76 ± 0.02 mm, and the sphericity was> 95%. The sphericity here was defined by the following equation.
Sphericality (%) = [1− (major axis−minor axis) ÷ {(major axis + minor axis) ÷ 2}] × 100

  Similarly to Example 1, solder balls were manufactured by actually using the manufacturing apparatus 1 according to the embodiment of the present invention described with reference to FIG. Solder (melt) sent from the raw material nozzle by feeding the silicone oil in the fluid container at 78 cm / sec, whereas the solder (melt) in the melting container was sent at 5.0 g / min. Was separated by the flow of silicone oil. Other conditions are the same as in the first embodiment described above. FIG. 7 is a sketch of an SEM photograph showing the appearance of the solder ball obtained in Example 2. When the particle size was evaluated from the photographic magnification, the solder ball diameter was 0.50 ± 0.02 mm, and the sphericity was> 95%. The sphericity here was defined in the same way as before.

It is explanatory drawing of the manufacturing apparatus of the spherical body concerning embodiment of this invention. It is an enlarged view which shows the positional relationship of a raw material nozzle and a fluid nozzle. It is an expanded sectional view of the tip of a raw material nozzle. It is an expanded sectional view of the front-end | tip of the raw material nozzle of another shape. It is an expanded sectional view of the front-end | tip of the raw material nozzle of another shape. 2 is a sketch of an SEM photograph showing the appearance of a solder ball obtained in Example 1. 4 is a sketch of an SEM photograph showing the appearance of a solder ball obtained in Example 2.

Explanation of symbols

1 Manufacturing apparatus a Solder ball a 'Solder (melt)
DESCRIPTION OF SYMBOLS 10 Apparatus main body 11 Molding part 12 Cooling part 13, 14 Band heater 20 Melt container 21 Fluid container 22, 25 Gas piping 23, 26 Gas cylinder 27 Melt piping 28 Raw material nozzle 29 Fluid piping 30 Fluid nozzle 32 Support block 33 Discharge port

Claims (7)

  The spherical material is discharged from the discharge port in the melt state, and when the discharge amount reaches a desired amount, the melt is separated at the discharge port by the flow of the fluid, and the separated spherical material is melted. A method for producing a spheroid, characterized in that the spheroid is solidified after being made spherical by surface tension in the above state.   The method for producing a spherical body according to claim 1, wherein the flow of the fluid is constant, or changes periodically or in a pulse manner.   The method for producing a spherical body according to claim 1 or 2, wherein the fluid is a gas or a liquid that does not react with the melt.   4. The method for producing a spherical body according to claim 1, wherein the spherical body is made of metal.   The method for producing a spherical body according to claim 4, wherein the raw material for the spherical body is a single metal or an alloy composed of two or more metals whose liquidus temperature of the melt is 450 ° C or lower.   The method for producing a spherical body according to any one of claims 1, 2, 3, 4 and 5, wherein the spherical body is a solder ball.   An apparatus for producing a spherical body, comprising: a raw material nozzle for discharging a spherical material in a melt state; and a fluid nozzle for supplying a fluid to the raw material nozzle from the side.

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