JP5257390B2 - Molten metal discharge device - Google Patents

Description

The present invention relates to a molten metal discharge apparatus that is preferably used when a molten metal such as molten solder is sucked and a predetermined amount of the sucked molten metal is discharged onto an object to be coated.

A brazing material such as solder is used to join a metal and a metal, a semiconductor element and a ceramic substrate, or a ceramic substrate and a base substrate. It is desirable that air does not intervene in the joining portion and that an oxide layer is not generated at the joining interface. In order to obtain good bonding quality, molten metal such as molten solder is often used for bonding.

As a specific example, a solder ball forming device disclosed in Patent Document 1 includes a solder storage unit that stores molten solder, a heater that maintains the temperature of the molten solder in a predetermined range, a communication path for molten solder and compressed non-oxidizing gas, It consists of an orifice that discharges molten solder, a switching valve that controls the supply of compressed non-oxidizing gas to the solder reservoir, an exhaust passage that maintains the pressure of the compressed non-oxidizing gas immediately above the molten solder at a predetermined pressure, and a discharge valve. Yes. The valve body of the switching valve is driven by a piezo actuator. An electromagnetic valve can also be used as the switching valve. When the compressed non-oxidizing gas is supplied to the solder reservoir, the molten solder in the solder reservoir is pushed out.

Other specific examples include a device for discharging molten solder with a syringe-like instrument described in Patent Document 2, and a device for pumping molten solder in a syringe described in Patent Document 3 with a plunger. .

JP 2001-77141 A (first page, FIG. 1) JP 2009-178639 A (first page, FIG. 1) Japanese Patent Laid-Open No. 10-137930 (first page, FIG. 1)

The solder ball forming apparatus disclosed in Patent Document 1 has a large number of parts and various components (various valves / actuators) for discharging a solder reservoir and solder, and is expensive. The solder generates an oxide film even with a small amount of oxygen, causing adhesion of molten solder to each path and deposition on the wall surface. If the oxide film is not periodically cleaned, quality degradation occurs during bonding due to clogging of the oxide film path and mixing of the oxide film into the discharged solder. In order to avoid this, it is necessary to replace or clean the members constituting the path. In the case of replacement, a large amount of money is required, and in the case of cleaning, a large amount of time is required. Further, in manufacturing, the solder application mechanism is moved to a position where application is desired. Since this apparatus is large and not suitable for high-speed movement, production efficiency is not high.

A molten solder discharge device disclosed in Patent Document 2 includes a molten metal holding container having a nozzle that discharges sucked molten metal to a target object, and heating that holds the molten metal contained in the molten metal holding container at a predetermined temperature. The apparatus includes a pressure control component for sucking or discharging molten metal from the nozzle by controlling the pressure in the molten metal holding container, and a heat-resistant seal related to the pressure control component. For this heat-resistant seal, a material mainly composed of a fluororesin such as Teflon (registered trademark) that has both slidability and heat resistance is preferably used. However, since the heat-resistant seal attached to the pressure control component slides inside the molten metal holding container, it wears out even if it is slidable for a long time. As a result, the molten metal holding container cannot maintain airtightness, and the discharge amount of the molten metal varies. Furthermore, when worn out, the molten metal cannot be sucked or discharged. As long as the heat-resistant seal is a material mainly composed of a fluororesin, the heat resistance of about 300 ° C. is the limit, and the heat-resistant seal cannot be used for a high-temperature molten metal.

The solder discharge device of Patent Document 3 includes a syringe in which solder is filled and stored in a molten state, a plunger that pumps molten solder in the syringe, and a device that drives and controls the plunger. In this configuration, when a large amount of solder is applied, the syringe needs to be large. Since a large-sized apparatus is not suitable for high-speed movement, if the syringe is downsized, it is necessary to frequently supply solder into the syringe, resulting in a reduction in production efficiency. Furthermore, regular cleaning also takes time due to the large number of parts. On the other hand, as a material for sealing the plunger and the syringe, graphite or a material obtained by adding boron nitride to graphite is used. The seal has a structure in contact with the solder although it is composed of a component different from the solder component. By repeating the coating operation, the seal component is mixed into the solder, which causes a reduction in the bonding quality.

The present invention has been made to solve the above-described problems of the prior art. That is, an object of the present invention is to provide a molten metal discharging apparatus that is small in size, simple and capable of high-speed movement, has high production efficiency, has a very low maintenance frequency, is easy to maintain, and can be obtained at low cost.

The molten metal discharging apparatus according to the present application is inserted into the syringe cylinder in which the first opening is provided at the lower end and the second opening is provided above the first opening, and the second opening of the syringe cylinder. A reciprocating piston, a first heating device that raises the temperature of the syringe cylinder in which the piston is inserted, a storage tank that opposes the first opening of the syringe cylinder and that accommodates the joining metal, and a storage tank And a second heating device for heating. A groove portion is provided on the outer periphery of the piston or the inner periphery of the syringe cylinder, and a bonding metal having the same component as the bonding metal housed in the storage tank is disposed on the entire periphery of the groove portion. A groove portion is provided on the outer periphery of the piston or the inner periphery of the syringe cylinder, and a bonding metal having the same component as the bonding metal housed in the storage tank is disposed on the entire periphery of the groove portion.

According to this invention, by using a molten metal holding container in which the inlet and outlet of the molten metal are the same nozzle, the storage tank for storing the molten metal and the portion for discharging the molten metal are separately configured. The discharge mechanism can be made small and simple. Therefore, high-speed movement is easy and production efficiency can be increased. In addition, since it is small and has a simple structure, it is inexpensive and easy to maintain.

As a pressure control component for controlling the pressure in the molten metal holding container, a molten metal seal composed of the same components as the molten metal to be sucked and discharged is used. Since the wear of the seal and the damage due to heat caused by repeating the operation of sucking the molten metal into the molten metal holding container and discharging it to the target object are reduced, maintenance becomes easy, and an inexpensive and high-productivity apparatus can be obtained. Furthermore, by handling high-temperature molten metal, options for bonding materials having different melting points are expanded, and further advanced bonding is possible.

2 is a cross-sectional view schematically showing a main part of the molten metal discharge apparatus according to Embodiment 1. FIG. The figure which concerns on Embodiment 1, the figure (a) which shows the piston in which the groove part which has a 1st form was formed, the figure (b) which shows the state by which the metal seal was wound around the groove part, and a piston is a syringe It is sectional drawing (c) which shows the state inserted in the pipe | tube, and sectional drawing (d) which shows the state in which the metal seal is fuse | melting in a syringe cylinder. It is a figure concerning Embodiment 2, and is sectional drawing (a) which shows the 2nd form of a groove part, and sectional drawing (b) which shows the 3rd form of a groove part. The figure which concerns on Embodiment 3 and is a figure explaining the front-end | tip shape of a syringe cylinder, The figure (a) which shows the 1st form of a nozzle, The figure (b) which shows the 2nd form of a nozzle, and the 3rd of a nozzle It is a figure (c) which shows the form of, and a figure (d) which shows the 4th form of a nozzle. It is a figure concerning Embodiment 4, and is a figure explaining the piston in which the pin is formed in the front-end | tip. It is a figure concerning Embodiment 5, and is a figure explaining the groove part provided in the inner periphery of a syringe cylinder.

Embodiment 1 FIG.
The first embodiment will be described with reference to FIG. FIG. 1 shows a schematic configuration of a molten metal discharging apparatus. The molten metal discharge device 8 includes a storage tank 1, a storage heater 3, an atmosphere furnace 6, a discharge mechanism unit 7, and a moving mechanism unit 14. Hereinafter, the same reference numerals denote the same or corresponding parts throughout the drawings.

The storage tank 1 accommodates a joining metal such as a brazing material in a molten state. A storage heater 3 is installed at the inner bottom portion of the storage tank 1 to hold the contained bonding metal in a molten state. The syringe warming heater 4 includes a cylindrical heater built-in block surrounding the periphery of the syringe 5. The syringe 5 is composed of a piston (pressure control component) 5 a and a syringe cylinder 5 b and is provided separately from the storage tank 1. The cylindrical piston 5a has a groove 5h formed in the middle. A nozzle 5c having a smaller diameter than the main body of the syringe cylinder is formed at the bottom of the syringe cylinder 5b. The nozzle 5 c faces the storage tank 1.

The syringe heat retaining heater 4 controls the syringe 5 within a predetermined temperature range by a temperature control device 12 including a temperature sensor. The syringe heat retaining heater 4 and the temperature control device 12 constitute a first heating device. The storage heater 3 controls the molten metal 2 within a predetermined temperature range by the temperature control device 11. The storage heater 3 and the temperature control device 11 constitute a second heating device. Instead of the syringe heat retaining heater 4, the syringe 5 may be heated by means such as radiation, induction heating, or convective heat transfer. The syringe warming heater 4, the syringe 5, and the actuator 10 constitute a discharge mechanism unit 7.

The piston 5a controls the internal pressure of the syringe 5 in cooperation with the syringe cylinder 5b. The syringe 5 sucks or discharges the molten metal 2 from the nozzle 5c. The molten metal 5d in the syringe is discharged to the target location of the application target. The actuator 10 reciprocates the piston 5a in the direction of the arrow (up and down) independently of the syringe cylinder 5b. The movement mechanism unit 14 arbitrarily controls the movement of the discharge mechanism unit 7 in, for example, three axial directions of X, Y, and Z orthogonal to each other.

The atmosphere furnace 6 surrounds the application target such as the storage tank 1, the discharge mechanism unit 7, the moving mechanism unit 14, and the ceramic substrate. The atmosphere furnace 6 is filled with, for example, an inert gas such as nitrogen or argon, a reducing gas such as hydrogen, or a mixed gas thereof. In the present application, these are referred to as “non-oxidizing gas” for convenience. The atmosphere furnace 6 suppresses the oxidation of the molten metal 2 by setting the storage tank 1 to a low oxygen atmosphere.

The material of the molten metal 2 is not particularly limited. As an example, Sn, Pb, Zn, Ga, In, Bi, Au, Ag, Cu, or a mixture containing these as a main component, or one of these can be preferably used as a brazing material for bonding. Mention may be made of alloys containing more than one type. As the material of the syringe 5, for example, when the molten metal 2 is solder containing Sn or Pb as a main component, glass, stainless steel, ceramics, or the like can be preferably used.

When a combination of these materials is used, it is difficult for solder to adhere to the piston 5a and the syringe cylinder 5b. All the melted solder is applied to the application object without remaining in the nozzle 5c. When a material such as glass that is difficult to transmit heat is used as the syringe 5, for example, the syringe heat retaining heater 4 is directly attached to the syringe 5 and heated to efficiently maintain the molten metal 5d in the syringe in a molten state.

The structure of the syringe 5 will be described more specifically. The syringe cylinder 5b has two openings, a piston is inserted from the upper opening, and molten metal is sucked and discharged from the lower opening (nozzle). Since the outer diameter of the piston 5a is smaller than the inner diameter of the syringe cylinder 5b, there is a gap between them. The size of the gap is set so that the piston 5a can smoothly reciprocate the syringe cylinder 5b. The syringe 5 is kept airtight by a molten metal seal 5e. The molten metal seal 5e is accommodated in a melted state in the groove 5h of the piston 5a, and the molten metal seal 5e moves as the piston 5a moves up and down. The molten metal seal 5e is stored in the molten state in the groove 5h of the piston 5a as described above using the same material as the molten metal 5d in the syringe discharged to the object.

By using the same material for the piston 5a and the syringe cylinder 5b, the gap between the piston 5a and the syringe cylinder 5b can be maintained at the same level even when the syringe 5 is heated. As for this gap, it is desirable to make the diameter of the piston 5a smaller by about 0.05 to 0.1 mm than the inner diameter of the syringe cylinder 5b. By adopting this dimensional relationship, the molten metal seal 5e formed of the molten metal 2 can be stably accommodated in the groove 5h, and the airtightness of the syringe 5 can be stably maintained. Even if a molten metal oxide film enters this gap, the sliding resistance of the piston 5a is not significantly affected because the oxide film is brittle. However, if the gap is smaller than this, the oxide film bites into the gap and the sliding resistance increases.

A method for forming the molten metal seal 5e will be described with reference to FIG. Fig.2 (a) has shown the piston 5a of the syringe 5, and the groove part 5h is processed into the piston 5a. FIG.2 (b) has shown the state which wound the wire-shaped metal 9 in the groove part 5h. The wire-like metal 9 is obtained by processing a brazing material (joining metal) for joining made of the same components as the molten metal 2 into a linear shape. FIG. 2C shows a state where the piston 5a is inserted into the syringe cylinder 5b. When the syringe heat retaining heater 4 is heated above the melting point of the wire-like metal 9, a molten metal seal 5e is formed as shown in FIG. Although FIG. 2 shows an example in which the molten metal seal 5e is formed by winding the wire-shaped metal 9 around the piston 5a, the metal 9 may be ribbon-shaped.

Next, the operation of the first embodiment configured as described above will be described. First, the atmosphere furnace 6 and the syringe 5 are filled with a non-oxidizing gas such as nitrogen gas in advance. A molten metal 2 as a brazing material is stored in the storage tank 1, and the molten metal 2 is held at a predetermined temperature by a storage heater 3. The syringe 5 is heated to a temperature equal to or higher than the melting point of the bonding metal by the syringe heat retaining heater 4. Since the temperature of the groove 5h of the piston 5a rises above the melting point of the bonding metal, the bonding metal is stored in a molten state. The piston 5a is pushed into the bottom of the syringe cylinder 5b.

Next, the nozzle 5 c of the syringe 5 is immersed in the molten metal 2 stored in the storage tank 1 by the moving mechanism unit 14. When the piston 5a is raised by the actuator 10, the inside of the syringe 5 is decompressed, and the molten metal 2 is sucked into the syringe 5 through the nozzle 5c. Then, the syringe 5 is raised by the moving mechanism unit 14, and the syringe 5 is moved to the target position of the application target. When the piston 5a is lowered by a predetermined amount by the actuator 10, the molten metal 2 is applied from the nozzle 5c to the target position of the application object.

The amount of the molten metal 2 to be sucked may be sucked by an amount necessary for an object to which the molten metal 2 is applied. The amount of suction can be increased or decreased by the length of the stroke for raising the piston 5 a provided in the syringe 5, and the amount of application can also be increased or decreased by the length of the stroke for lowering the piston 5 a of the syringe 5. In the case of multi-point application, the total amount of molten metal 2 necessary for multi-point application is sucked in advance. The syringe 5 is moved to the start point of the application position, the piston 5a is lowered by a required stroke, and the application is first performed at the start position. Further, the syringe 5 is moved to the next application position, and the piston 5a is moved down by a required stroke for application. Multi-point application can be easily performed by sequentially repeating this operation. It is easy to perform the above series of operations by automatic control.

As described above, according to the first embodiment, the storage tank 1 for the molten metal 2 and the discharge mechanism portion 7 are formed separately, and the suction port for replenishing the molten metal 2 and the discharge port for coating are the same nozzle. 5c. The internal pressure of the syringe 5 is lower than the external pressure by pulling the piston 5a upward. The syringe 5 sucks the molten metal 2 from the nozzle 5c, holds it in the internal space, and discharges the molten metal 5d in the syringe to the application object by increasing the pressure in the internal space. Thus, the molten metal discharging apparatus according to the present application has a simple configuration and can be provided at low cost.

Moreover, since the storage tank 1 of the molten metal 2 is disposed separately from the discharge mechanism section 7, the discharge mechanism section 7 can be configured to be compact and lightweight. Since the discharge mechanism unit 7 moves at high speed, processing with high productivity is possible. Furthermore, since the molten metal 2 can be applied in an arbitrary amount at an arbitrary position in a non-oxidizing atmosphere, high-quality bonding can be obtained.

In addition, if the surface in contact with the piston 5a or the molten metal 2 is made of a material that does not cause a chemical reaction with the molten metal, such as a metal having a non-moving oxide film, ceramics, or glass, it is unnecessary. Since no components are mixed in, it can be applied in the same component state as when sucked, and deterioration in bonding quality can be prevented.

Moreover, the oxidation of the surface of the molten metal 2 can be prevented by making the gas which the molten metal 2 contacts into a non-oxidizing gas. When the surface of the molten metal 2 is oxidized, the oxide film is also discharged from the nozzle 5c, so that it is mixed between the two parts to be joined, and the joining quality deteriorates. On the other hand, in this Embodiment 1, there is no such concern with the above configuration, and high-quality bonding can be obtained. Furthermore, when the piston 5a and the syringe cylinder 5b are made of the same material, even if heated by the syringe heat retaining heater 4, the gap between the piston 5a and the syringe cylinder 5b is maintained, so that airtightness can be ensured. Since there is no change in the ease of movement of the piston 5a, the discharge amount of the molten metal 2 can be controlled with high accuracy.

When the suction and discharge operations are repeated, the molten metal seal 5e slides inside the syringe 5. Since the molten metal seal 5e is a molten metal, there is no deterioration due to wear, and the shape can be freely changed in accordance with the seal surface. The discharge mechanism section 7 can stably discharge molten metal over a long period of time, and can efficiently produce parts without requiring maintenance. Even if a part of the molten metal seal 5e falls and enters the molten metal 2 to be discharged, the joining quality of the components is not adversely affected.

Embodiment 2. FIG.
The second embodiment will be described with reference to FIG. FIG. 3 illustrates two forms of grooves formed in the piston 5a. The shape of the molten metal seal 5e is different with the change of the groove 5h. In FIG. 3A, the length of the molten metal seal 5e is made longer than that in the first embodiment. Thereby, even if the molten metal forming the seal by the molten metal seal 5e is reduced, the sealing property can be maintained for a long time. In FIG. 3B, three groove portions 5h and three molten metal seals 5e are provided. Similarly to FIG. 3 (a), the sealing property can be maintained for a long period of time, and the sealing property is maintained by forming the seal in a plurality of parts.

In short, as long as the airtightness of the syringe 5 is maintained with the same material as that of the molten metal 2, the shape of the molten metal seal 5e may be any shape. Although FIG. 3B shows an example in which three molten metal seals 5e are installed, there is no problem even if the number is increased or decreased. Further, there is no problem even if the molten metal 2 is sucked and the molten metal 2 and the molten metal seal 5e are connected in the syringe cylinder 5b.

Embodiment 3 FIG.
The third embodiment will be described with reference to FIG. A nozzle 5c is provided at the bottom 5i of the syringe cylinder 5b, and molten metal is stored in the syringe. 4A to 4D show four types of shapes in the shape of the nozzle 5c. As shown in FIG. 4A, the accuracy of the coating amount can be improved by making the inner diameter of the nozzle 5c smaller than the inner diameter of the main body of the syringe cylinder 5b. This will be described below.

When the molten metal 2 is discharged onto the object, the molten metal 2 discharged onto the object and the molten metal 5d in the syringe are in a connected state. By raising the actuator 10, the nozzle 5c is also raised, and the discharged molten metal 2 and the molten metal 5d in the syringe are separated. At this time, the mass of the molten metal 2 applied to the object varies depending on the position at which the molten metal 2 is cut. That is, if the cutting position is always cut at a fixed position, the application amount of the molten metal 2 can be managed with high accuracy.

This is realized in the example of FIG. 4A, in which the inner diameter of the nozzle 5c is made smaller than the inner diameter of the syringe cylinder 5b. The molten metal 2 is always cut at the portion where the inner diameter of the nozzle 5c is reduced, and the coating accuracy is improved. In FIG. 4B, the nozzle outlet 5j is narrower than the base of the nozzle (the part where the nozzle starts from the bottom 5i of the syringe cylinder). If the inner diameter of the nozzle 5c is made smaller toward the tip, the position where the molten metal 2 after discharge is cut off is always the tip of the nozzle 5c in FIG. 4B, so that the coating accuracy is further improved.

In FIG.4 (c), the distinction with a nozzle and a syringe cylinder main body is not clear, and the front-end | tip of a syringe cylinder is gradually clogged. In this manner, the application accuracy can be similarly improved by gradually decreasing the inner diameter of the syringe cylinder 5b toward the tip of the nozzle 5c. On the other hand, when the application accuracy of the molten metal 2 is not concerned, the inner diameters of the syringe cylinder 5b and the nozzle 5c may be the same as shown in FIG. It is also conceivable to make the inner diameter of the nozzle 5c larger than the syringe cylinder 5b.

Embodiment 4 FIG.
The fourth embodiment will be described with reference to FIG. The more the atmosphere furnace 6 is kept at a lower oxygen concentration, the higher the cost. Therefore, the configuration shown in FIG. 5 is one in which the oxygen concentration is slightly increased so that the molten metal 2 can be stably sucked and discharged even if the generation of an oxide film increases. A pin 5g having a smaller diameter than the inner diameter of the nozzle 5c is provided at the tip of the piston 5a. The pin 5g prevents clogging of the nozzle 5c where an oxide film is easily deposited. Although the oxide film is deposited also inside the syringe cylinder 5b, since the molten metal seal 5e is in a molten state, the molten metal seal 5e freely changes its shape to the unevenness of the oxide film so that the sealing performance does not deteriorate. It is possible to maintain the internal airtightness of the syringe cylinder 5b.

Here, it is expensive to maintain the atmosphere furnace 6 at a low oxygen concentration. By providing a pin 5g at the tip of the piston 5a as shown in FIG. 5, the molten metal 2 can be stably sucked and discharged. In the point which can be done, the molten metal seal | sticker 5e also changes to an oxide film gradually by oxidation, and the molten metal seal | sticker 5e decreases. Therefore, the sealability can be maintained for a long time by using the seal shape as shown in FIG. 3 together with the pin 5g of FIG.

Embodiment 5 FIG.
The fifth embodiment will be described with reference to FIG. FIG. 6 shows that the groove 5h is provided on the inner peripheral side of the syringe cylinder 5b, and the molten metal seal 5e is in contact with the outer periphery of the piston 5a at the insertion port of the syringe cylinder 5b. This is suitable when the piston 5a is too thin and it is difficult to form the molten metal seal 5e on the piston 5a.

In the description of each of the above embodiments, the case where the target object is applied as the application object when the molten metal 2 is discharged from the nozzle 5c of the syringe 5 has been described as an example. It is not a thing. For example, it can be dropped or adhered to the target object. The types of the molten metal 2, the shape and material of the syringe 5, and the configuration of the pressure control device (piston) are only examples for carrying out the present invention, and other modifications and changes are possible. Needless to say.

  DESCRIPTION OF SYMBOLS 1 Reservoir, 2 Molten metal, 3 Storage heater, 4 Syringe heat retention heater, 5 Syringe, 5a Piston, 5b Syringe cylinder, 5c Nozzle, 5d Molten metal in syringe, 5e Molten metal seal, 5g pin, 5h Groove, 5i Syringe Tube bottom, 5j Nozzle outlet, 6 Atmosphere furnace, 7 Discharge mechanism, 8 Molten metal discharge device, 9 Wire-shaped metal, 10 Actuator, 14 Moving mechanism

Claims (8)

A syringe cylinder in which a first opening is provided at a lower end and a second opening is provided above the first opening; a piston which is inserted into the second opening of the syringe cylinder and reciprocates; A first heating device that raises the temperature of the syringe cylinder in which the piston is inserted, a storage tank that opposes the first opening of the syringe cylinder and that contains the joining metal, and a second temperature that raises the temperature of the storage tank. In a molten metal discharge device provided with a heating device of
A groove is provided on the outer periphery of the piston or the inner periphery of the syringe cylinder, and a bonding metal having the same component as the bonding metal accommodated in the storage tank is disposed on the entire periphery of the groove. Molten metal discharge device. The molten metal discharging apparatus according to claim 1, wherein the bonding metal disposed on the entire circumference of the groove is melted. The molten metal discharging apparatus according to claim 1, further comprising an atmosphere furnace that surrounds the storage tank, the syringe cylinder, and the piston and is shielded from the surroundings by a non-oxidizing gas. The molten metal discharging apparatus according to claim 1, wherein a plurality of grooves are provided in the piston. The molten metal discharging apparatus according to claim 1, wherein a nozzle having a smaller diameter than a main body of the syringe cylinder is formed at a bottom portion of the syringe cylinder. The molten metal discharging apparatus according to claim 5, wherein an outlet of the nozzle is narrower than a base of the nozzle. The molten metal discharge device according to claim 5, wherein a pin thinner than an inner diameter of the nozzle is provided at a tip of the piston. The molten metal discharging apparatus according to claim 1, wherein the syringe cylinder gradually narrows toward the lower end.

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