JP6106852B2 - Nozzle head, metal particle manufacturing apparatus using the nozzle head, and metal particle manufacturing method - Google Patents

Description

  The present invention relates to a nozzle head for discharging a liquid material, and an apparatus and method using the nozzle head. In particular, the present invention relates to a nozzle head that discharges a molten metal material to produce particles having uniform dimensions, and an apparatus and method using the nozzle head.

  Uniform particles with uniform shapes are widely used in various fields including electric products regardless of their materials. For example, uniform particles of silicon dioxide produced by a sol-gel method are widely used as means for ensuring the interval between glass plates with high precision in liquid crystal panels.

  Also, solder particles are used for the electrode portions for connection to the circuit board of the semiconductor IC package. This solder particle is called a ball grid array because the electrode arrangement of the semiconductor IC package is in a lattice shape.

  As means for producing the solder particles, as shown in Patent Document 1, an atomizing method in oil in which molten solder is discharged into high-temperature oil and spheroidized by surface tension is generally used. However, the molten solder is subjected to resistance by oil and its sphericity is lowered. In order to solve this problem, Patent Document 2 proposes discharging molten metal into the air using a piezoelectric actuator.

  A method for producing solder particles of Patent Document 2 will be described with reference to a sectional view of the nozzle head 300 of FIG. In FIG. 6, the metal material 352 is melted inside the nozzle head 300. The molten metal material 352 is pushed by the piston 320, and the metal material 352 is discharged from the nozzle 303. After the discharge, the metal material 352 is solidified and spherical solder particles are produced. The piston 320 is pushed by the piezoelectric element 330.

JP-A-11-207493 JP 2002-155305 A

  However, when the metal material 352 is melted, temperature distribution occurs in the tank for melting, and the temperature of the melted metal material 352 is not stable. Accordingly, the components of the molten metal material 352 are not homogenized, and the composition of the discharged metal material 352 is biased. Therefore, there is a problem that the shape of the solder particles when solidified is not stable.

  Further, the viscosity of the molten metal material 352 varies depending on the temperature. For this reason, if the temperature is not stabilized, the viscosity of the molten metal material 352 to be discharged is not stabilized. Therefore, there has been a problem that the diameter of solder particles to be formed varies.

  The present invention has been made in view of the above point, and a nozzle head capable of constantly homogenizing the components of the molten metal to be discharged and keeping the discharge volume constant, and metal particles using the nozzle head It aims at providing a manufacturing apparatus and the manufacturing method of a metal particle.

  In order to solve the above problems, a nozzle that discharges molten metal, a pressure chamber that generates pressure for discharging the molten metal through the nozzle, a supply chamber that supplies the molten metal to the pressure chamber, and a pressure chamber and supply A nozzle head including a piston that transmits pressure and a pressurizing unit that moves the piston, a first heating mechanism that heats the pressure chamber and the supply chamber, and a piston A nozzle head provided with a second heating mechanism for heating is used.

  Moreover, the metal particle manufacturing apparatus using the said nozzle head is used.

  A first heating step for heating the supply chamber for supplying the metal and a pressure chamber for pressurizing the metal to melt the metal; and a second heating step for heating the piston located across the pressure chamber and the supply chamber; A metal particle manufacturing method including a pressurizing step of pressurizing the molten metal with a piston and a discharging step of discharging the molten metal from a nozzle in the pressure chamber is used.

  As described above, according to the present invention, it is possible to configure a nozzle head capable of constantly convection of a molten metal material in a pressure chamber and always maintaining a constant temperature distribution of the molten metal. Therefore, the volume of the molten metal material to be discharged can be constant with a uniform composition at all times. Moreover, sphere formation with a desired metal composition can be performed with high accuracy. Therefore, it is possible to manufacture metal balls having a uniform shape and a uniform shape.

Sectional drawing which shows the structure of the nozzle head which concerns on embodiment of this invention (A) A sectional view showing a state in which a metal material is supplied to a pressure chamber and a supply chamber in the nozzle head of the present invention, (b) a section showing a state in which the metal material is melted in the pressure chamber and the supply chamber in the nozzle head of the present invention. FIG. 3C is a sectional view showing a state in which the nozzle head drive unit of the present invention is inserted, and FIG. Sectional drawing which shows the state of the metal material in the pressure chamber which concerns on embodiment of this invention Graph showing the relationship between the viscosity of molten metal and temperature Sectional drawing which shows the modification of the piston which concerns on embodiment of this invention Sectional view showing the structure of a conventional nozzle head

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<Configuration>
FIG. 1 is a schematic diagram illustrating a cross-sectional structure of a nozzle head according to an embodiment as viewed from the front. The nozzle head 100 is provided with a supply chamber 102 for storing a metal material as a raw material. A heating mechanism 141 is provided around the supply chamber 102 and heats and melts the metal material to the melting point or higher. The nozzle head 100 also includes a nozzle 103 that discharges molten metal. Further, a pressure chamber 104 that communicates with the nozzle 103 and generates a pressure for discharging the molten metal material is provided. The supply chamber 102 and the pressure chamber 104 are separated by a piston 120. Therefore, the pressure chamber 104 is heated from the outside simultaneously with the supply chamber 102 by the heating mechanism 141. The upper portion of the pressure chamber 104 is sealed with a partition wall 107.

  The piston 120 is connected to a piezoelectric element 130 that generates thrust, and has a function of transmitting the thrust of the piezoelectric element 130 to the pressure chamber 104. The piezoelectric element 130 is fixed by the bracket 105. The piezoelectric element 130 is electrically connected to the external power source 131 and can be driven by the external power source 131. The tip 121 of the piston 120 on the pressure chamber 104 side is processed into a spire shape. Furthermore, the piston 120 is provided with a heating mechanism 142 to heat the piston 120. Thereby, the supply chamber 102 and the pressure chamber 104 can be heated from the inside.

The nozzle head 100 is fixed to a table (not shown) or the like by a fixture 106.
<Supply of metal materials>
Next, a method for supplying a material to the nozzle head 100 will be described. FIG. 2A to FIG. 2D are schematic views showing a cross-sectional structure of the pressure tank 202, that is, the supply chamber 102 and the pressure chamber 104, as viewed from the front, in the nozzle head 100.

  In FIG. 2A, a metal material 151 for discharging with a desired composition is introduced into the pressure chamber 104 and the supply chamber 102. Here, the metal material 151 will be described by taking a solder material as an example, but the same applies to a material such as copper or silicon. The introduced metal material 151 is heated by a heating mechanism 141 provided around the pressure chamber 104 and the supply chamber 102.

  Since the melting point of the solder material having a tin-silver-copper composition used for mounting a general electronic circuit is 221 ° C., it can be melted by heating to a temperature higher than that.

  FIG. 2B shows a state in which the lower part of the pressure chamber 104 and the supply chamber 102 is filled with the molten metal material 152. In addition, although the figure which supplied the metal material 151 processed into the granular form beforehand is shown here, even if it is a ribbon form or an ingot form, it melts into the pressure chamber 104 and the supply chamber 102 by melting sequentially by heating above the melting point. Since the metal material 152 is filled, it can be used without any problem.

  Next, in FIG. 2C, the nozzle head 100 inserts the piston 120 into the pressure chamber 104. Further, FIG. 2D shows a state in which the molten metal material 152 is discharged.

  In this state, the pressure chamber 104 and the supply chamber 102 are separated by the piston 120. Note that the pressure chamber 104 and the supply chamber 102 are not completely independent, and are processed so as to provide a predetermined gap 108 between the pressure chamber 104 and the piston 120 in advance.

  As a result, the decrease due to the discharge of the metal material 152 in the pressure chamber 104 can be supplemented from the supply chamber 102, and a certain amount of the metal material 152 can always be held in the pressure chamber 104.

  In addition, the piston 120 is also provided with a heating mechanism 142, so that the molten metal material 152 is not solidified by the insertion of the piston 120 and the insertion of the piston 120 is not hindered. Preheated.

  The nozzle 103 is circular. The diameter of the nozzle 103 is about 0.5 mm at the maximum, and due to the effect of the high surface tension of the molten metal material 152, the nozzle 103 is not dropped by gravity. The nozzle 103 is not limited to a circular shape, and may be an elliptical shape.

<Drive>
Next, the drive mechanism of the nozzle head 100 will be described. In FIG. 2D, the rear end portion 122 of the piston 120 is connected to the piezoelectric element 130 by an adhesive or a pressurizing mechanism, and the thrust of the piezoelectric element 130 is transmitted. Here, when the piezoelectric element 130 is driven by the external power source 131, the operation is transmitted to the pressure chamber 104 through the piston 120. The operation of the piston 120 increases the pressure in the pressure chamber 104, and the pressure leads to the discharge of the molten metal material 152 from the nozzle 103 that is the open end. At this time, the pressure chamber 104 and the piston 120 have a gap 108 for supplying the molten metal material 152 to the pressure chamber 104, but the flow path resistance is larger than the flow path resistance of the nozzle 103. The pressure in 104 almost functions as discharge from the nozzle 103.

  The discharged metal material 152 becomes spherical due to its surface tension, and is cooled in the air to form a sphere. At this time, in order to suppress oxidation of the surface, it is desirable to discharge and cool in an inert gas atmosphere such as nitrogen.

<State of metal material>
Next, the state of the molten metal material 152 in the pressure chamber 104 will be described in detail. FIG. 3 is an enlarged cross-sectional view of the pressure chamber 104. Here, the temperature of the metal material 152 in the pressure chamber 104 by the heating mechanism 141 is adjusted to be higher than the temperature of the piston 120 by the heating mechanism 142.

  As an example, the case where it forms from the alloy of tin, silver, and copper as a metal material is shown. For tin, silver and copper alloys, the melting point is 221 ° C. Here, the temperatures of the heating mechanisms 141 and 142 are set to be 245 ° C. and 235 ° C., respectively. In this case, the temperature difference between the heating mechanisms 142 and 141 generates a smooth temperature gradient through the molten metal material 152 in the pressure chamber 104, so that the molten metal itself has a temperature of 5 ° C. from the center to the end. A temperature difference of the order is generated, and a temperature difference of 2 to 3 ° C. or more necessary for effective convection generation can be provided. There should be a temperature difference of at least 2 ° C or more, preferably 3 ° C or more.

  Thereby, the temperature of the molten metal material 152 around the pressure chamber is increased, and an upward flow 161 is generated. The upward flow 161 eventually reaches the tip 121 of the piston. Here, since the temperature of the piston 120 is set lower than the temperature of the pressure chamber 104, the piston 120 is slightly cooled and the upward flow 161 shifts to the downward flow 162. At this time, the tip part 121 of the piston 120 is formed in a spire shape, so that the upward flow 161 from the periphery follows the shape of the spire-like tip part 121 and is guided as a downward flow 162 to the center of the pressure chamber. On the other hand, the transition from the upward flow to the downward flow is performed without stagnation. Thereby, the metal material 152 melted in the pressure chamber 104 can generate stable convection. Therefore, the molten metal material 152 can always maintain a constant temperature distribution in the pressure chamber 104.

  This stable convection generation results in stable stirring and leads to the composition of the molten metal material 152 being always kept constant. In particular, when the metal material is made of a composite material, uneven distribution of various materials resulting from a difference in specific gravity for each component contained can be suppressed. This always leads to the discharge of a homogeneous metal material.

  Furthermore, since the temperature distribution is stably obtained, the viscosity of the molten metal material can be kept constant.

  FIG. 4 is a graph showing the relationship between the melt viscosity and temperature in a solder material made of tin-silver-copper as the metal material 152.

  As shown in the graph of FIG. 4, the metal material 152 melts at a melting point of 220 ° C., and changes its state from a solid to a liquid. As a result, the viscosity of the metal material 152 suddenly decreases. The molten material of the metal material 152 is discharged from the nozzle 103 in a temperature range where the temperature is raised by about 20 ° C. from the melting point of the metal material 152. This is to ensure that a part of a material that does not completely melt and liquefy due to uneven temperature distribution and exists in a solid or solid solution state is surely avoided. Moreover, this part has a drastic change in viscosity. Therefore, it is understood that the temperature needs to be kept constant. If the temperature is higher, there are adverse effects such as material modification and device deterioration.

  Here, in the case of the nozzle head 100 using the piezoelectric element 130 shown above, since the discharge volume changes due to the change in the discharge resistance due to the viscosity, the viscosity is required to secure a stable volume. Stabilization is important.

  Since the melting temperature of the metal material 152 is usually a temperature range higher than room temperature, it is difficult to keep the temperature uniform, and a temperature distribution always occurs. However, in the present embodiment, this inevitable temperature distribution is not lost, but conversely, as shown in FIG. 3, the temperature distribution is always kept constant by positively generating convection. , So as not to change. Accordingly, the temperature of the metal material in the vicinity of the nozzle 103 to be discharged is always kept constant, so that the discharge volume can be stabilized.

  Here, as shown in FIG. 2D, the replenishment of the metal material 152 in the pressure chamber, which has been reduced by the discharge, is performed from the supply chamber 102 through the gap 108 between the pressure chamber 104 and the piston 120. There is a concern about the temperature change. However, the volume of the material ejected by the generated pressure in the nozzle jet is about 100 picoliters to about 1 microliter at the maximum. This is sufficiently small compared with the pressure chamber volume of 1 to 10 ml, and the temperature change due to the replenishment of the metal material is not a problem.

  At this time, in FIG. 2D, the piston 120 has a diameter of 8 mm, and the pressure chamber is formed so that the gap 108 is about 50 μm to 100 μm. The replenishment of the metal material 152 is performed when the piston 120 moves forward and discharges the metal material 152 and then moves back to the initial position, and the metal material 152 corresponding to the discharged volume flows into the pressure chamber through the gap 108. To be replenished.

  The opening area of the gap 108 is preferably larger than the opening area of the nozzle 103. This reason is for ensuring the stability of the volume of the molten metal discharged. The diameter of the nozzle 103 is preferably larger than the minimum gap distance of the opening portion of the gap 108.

<Modification>
In FIG. 1, a conical shape is shown as the shape of the tip 121 of the piston 120, but the tip 123 may be hemispherical as shown in FIG. The same effect can be obtained if the object is a target to be rotated with the center line as the base line, such as an oval, spindle, or truncated cone.

Further, the lower portion of the pressure chamber 104 has a structure that narrows as it reaches the nozzle 103, which is designed so that the pressure generated by the thrust of the piston 120 is concentrated on the nozzle 103. . In FIG. 1, the lower portion of the pressure chamber 104 has a similar shape to the piston 120, but is not limited thereto.
When the lower portion of the pressure chamber 104 is a cone, the apex angle is suitably about 30 to 150 degrees, preferably about 90 degrees ± 10 degrees.

  In the nozzle head of the present invention, when the metal material is melted and discharged, the composition thereof is homogenized, and a stable volume can always be discharged. In particular, when forming a sphere with molten metal, it can be manufactured with high diameter accuracy.

DESCRIPTION OF SYMBOLS 100 Nozzle head 102 Supply chamber 103 Nozzle 104 Pressure chamber 105 Bracket 106 Fixture 107 Bulkhead 108 Gap 120 Piston 121 Front end 122 Rear end 123 Front end 130 Piezoelectric element 131 External power supply 141 Heating mechanism 142 Heating mechanism 151 Metal material 152 Metal material 161 Upflow 162 Downflow 202 Pressure tank 300 Nozzle head 303 Nozzle 320 Piston 330 Piezoelectric element 352 Metal material

Claims (9)

A nozzle for discharging molten metal;
A pressure chamber that generates pressure for discharging the molten metal through the nozzle;
A supply chamber that supplies the molten metal to the pressure chamber, a piston that is located across the pressure chamber and the supply chamber, and that transmits pressure;
A pressurizing unit for moving the piston;
A nozzle head comprising:
A first heating mechanism for heating the pressure chamber and the supply chamber;
A second heating mechanism for heating the piston ,
The nozzle head in which the temperature of the pressure chamber and the supply chamber by the first heating mechanism is higher by 2 ° C. than the heating temperature of the piston by the second heating mechanism . The nozzle head according to claim 1 , wherein a shape of a tip portion of the piston is a spire shape. The nozzle head according to claim 2 , wherein the angle of the tip of the spire is 30 degrees to 150 degrees. It said piston and nozzle head according to any one of claims 1 to 3, there is a gap between the pressure chamber. The nozzle head according to claim 4 , wherein an opening area of the gap is larger than an opening area of the nozzle. Minimum distance, the nozzle head having a diameter smaller claim 4 or 5, wherein the nozzle opening portion of the gap. The gap, a nozzle head according to any one of claims 4-6 is 100μm from 50 [mu] m. The metal particle manufacturing apparatus using the nozzle head of any one of Claim 1 to 7 . A first heating step of heating a supply chamber for supplying metal and a pressure chamber for pressurizing the metal, and melting the metal;
A second heating step of heating a piston located across the pressure chamber and the supply chamber; and a pressurizing step of pressurizing the molten metal with the piston;
From a nozzle of said pressure chamber, it viewed including the discharge process, a for discharging the molten metal,
The metal particle manufacturing method which made temperature of the said pressure chamber and the said supply chamber in the said 1st heating process 2 degreeC or more higher than the heating temperature of the said piston in the said 2nd heating process .

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