Soldering device

Abstract

To provide a technology capable of reducing a volume of a void in solder.SOLUTION: A soldering device solders a processing target object provided with solder. The soldering device includes a chamber and a pressure cooling section. The chamber air-tightly seals a periphery of the processing target object in which solder is melted. The pressure cooling section pressurizes the inside of the chamber with a pressure higher than the atmospheric pressure, so that a volume of a void in the solder is reduced and the solder in the chamber is cooled and solidified.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] This disclosure relates to a soldering apparatus.

Background Art

[0002] Conventionally, solder is often used for surface bonding, such as between a chip and a substrate or between a substrate and a base. However, it is known that voids such as bubbles exist in the solder due to gases contained in, for example, flux. If such voids exceed a certain size, there are problems such as the generation of waste loss of the workpiece due to not meeting certain quality requirements or the occurrence of labor for X-ray inspection.

[0003] In response to such problems, Patent Document 1 proposes a technique of expanding voids in solder and discharging them outside the solder by reducing the pressure around the workpiece.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, voids may remain in the solder even with the technique of Patent Document 1. In such a case, when the solder solidifies in a state where the pressure around the workpiece is reduced, there is a problem that the voids remain in the solder in a state of being enlarged by the pressure reduction.

[0006] Therefore, this disclosure has been made in view of the above problems, and an object thereof is to provide a technique capable of reducing the volume of voids in solder.

Means for Solving the Problems

[0007] The soldering apparatus according to this disclosure comprises a chamber that hermetically seals the area around a workpiece on which solder has been molten, and a pressurized cooling unit that pressurizes the inside of the chamber to a pressure higher than atmospheric pressure and cools and solidifies the solder inside the chamber. [Effects of the Invention]

[0008] According to this disclosure, the inside of the chamber is pressurized to a pressure higher than atmospheric pressure, and the solder inside the chamber is cooled and solidified. With this configuration, the volume of voids in the solder can be reduced. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic cross-sectional view showing the configuration of a soldering apparatus according to Embodiment 1. [Figure 2] This is a side view showing an example of a workpiece according to Embodiment 1. [Figure 3] This is a schematic cross-sectional view showing the configuration of a soldering apparatus according to Embodiment 2. [Figure 4] This is a schematic cross-sectional view showing the configuration of a soldering apparatus according to Embodiment 3. [Modes for carrying out the invention]

[0010] The embodiments will be described below with reference to the attached drawings. The features described in each of the embodiments below are illustrative, and not all features are necessarily required. In addition, in the descriptions below, the same or similar reference numerals are used for similar components in multiple embodiments, and the different components are mainly described. Also, in the descriptions below, specific positions and directions such as "top," "bottom," "left," "right," "front," or "back" do not necessarily have to coincide with the positions and directions in actual implementation.

[0011] <Embodiment 1> Figure 1 is a schematic cross-sectional view showing the configuration of a soldering apparatus 51 according to this first embodiment. In the following description, the soldering apparatus 51 will be described as having a tunnel-type reflow oven, but it is not limited to this. The soldering apparatus 51 may be a batch-type or fixed-type apparatus, for example, as long as it can achieve the same functions as described below.

[0012] The soldering apparatus 51 in Figure 1 performs soldering as a processing method for the workpiece 1. The soldering apparatus 51 comprises a belt 3, a tunnel 4, a heat source unit 5, a fan 6, chambers 7a, 7b, 10a, 10b, chamber drive units 7c, 10c, pressure reduction units 8, 12, and gas introduction units 9, 11.

[0013] Figure 2 is a side view showing an example of workpiece 1. Workpiece 1 is a workpiece to be processed on which solder 43 is provided. In the example of Figure 2, workpiece 1 comprises a semiconductor element 41, a part to be joined 42, solder 43, and a heat exchange pin fin 44 having protrusions 44a. Before being fed into the soldering machine 51, the solder 43 does not join the semiconductor element 41 and the part to be joined 42.

[0014] As shown in Figure 1, workpiece 1 is placed on pallet 2, and pallet 2 is placed on belt 3 and transported through tunnel 4. The atmosphere inside tunnel 4 is generally nitrogen.

[0015] The soldering apparatus 51 in Figure 1 performs step-by-step processing on the workpiece 1. That is, the workpiece 1 is transported a predetermined distance at a time, and predetermined processing is performed on the workpiece 1 in the area where it is transported. The soldering apparatus 51 performs preheating, melting, and cooling processes on the solder 43 of the workpiece 1. For this reason, at least three areas are provided within the tunnel 4.

[0016] In the example of FIG. 1, six regions (first to sixth regions 4a to 4f) are provided in the tunnel 4. In the first to third regions 4a to 4c, preheating is performed, in the fourth region 4d, melting is performed, and in the fifth and sixth regions 4e and 4f, cooling is performed, whereby the work 1 is soldered. Note that the number of regions provided in the tunnel 4 is not limited to six, and at least three regions may be provided. Each region is separated by a partition wall except for the portion through which the work 1 passes. Note that a plurality of works 1 may be sequentially loaded into the soldering apparatus 51 and processed in parallel.

[0017] Next, the first to sixth regions 4a to 4f will be described.

[0018] In each of the first to third regions 4a to 4c, a heat source unit 5 and a fan 6 are provided, and the heat source unit 5 and the fan 6 circulate hot air so that the inside of each region reaches a predetermined temperature. The lower diagram in FIG. 1 shows an example of the temperature change of the work 1. In the first region 4a and the second region 4b, the work 1 is gradually heated to a temperature below the melting point of the solder 43. In the third region 4c, in order to improve the quality of soldering, the temperature of the entire work 1 is made uniform at a temperature below the melting point of the solder 43. The third region 4c can be omitted for the work 1 having a small heat capacity.

[0019] In the fourth region 4d, chambers 7a and 7b, a chamber driving unit 7c, a decompression unit 8, and a gas introduction unit 9 are provided. The chambers 7a and 7b are detachably moved with respect to the pallet 2 by the driving of the chamber driving unit 7c, and sandwich the pallet 2 to hermetically seal the periphery of the work 1. Although not shown, for example, by providing a rubber-like seal portion on the mating surface of the chambers 7a and 7b, the airtightness can be improved.

[0020] In a state where the work 1 is hermetically sealed by the chambers 7a and 7b, the gas introduction unit 9 supplies a gas such as nitrogen, and the decompression unit 8 makes the inside of the chambers 7a and 7b lower than the atmospheric pressure. The temperature of the gas supplied from the gas introduction unit 9 is preferably higher than the melting point of the solder 43, and the lowest temperature thereof is a temperature at which the solder 43 does not solidify due to gas introduction.

[0021] In such a fourth region 4d, with the interiors of the chambers 7a and 7b in a depressurized state, the workpiece 1 is heated to a temperature equal to or higher than the melting point of the solder 43. As a result, the solder 43 provided on the workpiece 1 melts, and voids within the solder 43 expand and are discharged outside the solder 43.

[0022] The fifth region 4e is provided with chambers 10a and 10b, a chamber drive unit 10c, a gas introduction unit 11 such as a gas nozzle, and a decompression unit 12. The chambers 10a and 10b are detachably moved relative to the pallet 2 by the drive of the chamber drive unit 10c and sandwich the pallet 2. Thereby, the chambers 10a and 10b hermetically seal the periphery of the workpiece 1 in which the solder 43 has melted in the fourth region 4d. Although not shown, for example, providing a rubber-like seal portion on the mating surface of the chambers 10a and 10b can enhance the airtightness.

[0023] With the solder 43 melted and the workpiece 1 hermetically sealed by the chambers 10a and 10b, the gas introduction unit 11 pressurizes the interior of the chambers 10a and 10b and introduces a gas such as nitrogen that cools the solder 43 to a temperature lower than the melting point. Thereby, the gas introduction unit 11 pressurizes the interior of the chambers 10a and 10b to a pressure higher than atmospheric pressure and cools and solidifies the solder 43 within the chambers 10a and 10b. Note that the pressurizing gas supplied from the gas introduction unit 11 and the cooling gas supplied from the gas introduction unit 11 may be different from each other. The decompression unit 12 is provided to prevent the pressure inside the chambers 10a and 10b from becoming too high.

[0024] The sixth region 4f is provided with a fan 6 in the same manner as the first region 4a and the like, and the fan 6 adjusts the cooling air so that the interior of the sixth region 4f reaches a relatively low predetermined temperature.

[0025] <Summary of Embodiment 1> According to the soldering apparatus 51 of this embodiment 1 described above, the inside of chambers 10a and 10b is pressurized to a pressure higher than atmospheric pressure, and the solder 43 inside chambers 10a and 10b is cooled and solidified. Since the volume of voids decreases as the pressure increases, with this configuration, the solder 43 can be solidified with a small volume of voids. As a result, the volume of voids in the solder layer formed by the solidification of the solder 43 can be reduced.

[0026] Furthermore, if paste solder is used for solder 43, and the flux contained in the paste is removed after soldering using a cleaning equipment (not shown), a product of good quality can be obtained.

[0027] <Embodiment 2> Figure 3 is a schematic cross-sectional view showing the configuration of chambers 10a and 10b of the soldering apparatus 51 according to this second embodiment. As shown in Figure 3, the soldering apparatus 51 includes a first on-off valve 20, a high-pressure backflow prevention valve 21, a second on-off valve 22, and a normal-pressure backflow prevention valve 23 as a mechanism that can variably change the backflow prevention pressure.

[0028] A high-pressure backflow prevention valve 21, which can be adjusted to a pressure higher than atmospheric pressure, is connected to the inside of chambers 10a and 10b via a first on-off valve 20. A normal-pressure backflow prevention valve 23, which can be adjusted to atmospheric pressure, is connected to the inside of chambers 10a and 10b via a second on-off valve 22. By selectively connecting the high-pressure backflow prevention valve 21 and the normal-pressure backflow prevention valve 23 to chambers 10a and 10b using the first on-off valve 20 and the second on-off valve 22, a mechanism is realized that allows for variable changes in the backflow prevention pressure.

[0029] Generally, if the gas flow rate from the gas inlet 11 is not increased, the solder cannot be cooled rapidly, which can cause shrinkage cavities in the solder layer. Therefore, to increase the gas flow rate, it is effective not only to send gas into the chambers 10a and 10b, but also to discharge the gas that has exchanged heat with the workpiece 1 and successively introduce low-temperature gas. On the other hand, in order to open the chambers 10a and 10b in the fifth region 4e in order to transport the workpiece 1 to the sixth region 4f, it is preferable to make the internal pressure of the chambers 10a and 10b equivalent to atmospheric pressure.

[0030] <Summary of Embodiment 2> Therefore, in this second embodiment, during cooling, the second on-off valve 22 is closed and the first on-off valve 20 is opened to use the high-pressure backflow prevention valve 21. This allows gas to be introduced at high pressure from the gas introduction section 11 while simultaneously being discharged at high pressure, thereby reducing shrinkage cavities in the solder layer. On the other hand, when discharging the workpiece 1 and pallet 2, the first on-off valve 20 is closed and the second on-off valve 22 is opened to use the atmospheric pressure backflow prevention valve 23. This allows the gas inside chambers 10a and 10b to be discharged to return from high pressure to atmospheric pressure, thereby returning the pressure inside chambers 10a and 10b to atmospheric pressure.

[0031] Alternatively, the temperature of the gas discharged to the outside of the high-pressure backflow prevention valve 21 may be lowered using a heat exchange means, and the gas may be sent to the gas inlet 11 for reuse. With such a configuration, the amount of gas used can be reduced. On the other hand, if the gas discharged to the outside of the high-pressure backflow prevention valve 21 is simply released, the entire soldering apparatus 51 can be miniaturized.

[0032] <Embodiment 3> Figure 4 is a schematic cross-sectional view showing the configuration of the soldering apparatus 51 according to this third embodiment. The configuration in Figure 4 is the same as that in Figure 1, except for the fifth region 4e.

[0033] The soldering apparatus 51 includes a gas circulation mechanism 30 located inside the chambers 10a and 10b in the fifth region 4e of Figure 4. With this configuration, the cooling capacity for the workpiece 1 can be increased by introducing cooling gas during cooling while operating the gas circulation mechanism 30. In the example in Figure 4, the gas circulation mechanism 30 is a fan, but it is not limited to this.

[0034] Generally, when the pressure of gas in a container of a certain volume increases, the temperature inside the container rises. Therefore, even if low-temperature gas is introduced into chambers 10a and 10b from the gas inlet 11, pressurizing chambers 10a and 10b tends to weaken the cooling capacity of the low-temperature gas. Furthermore, as shown in Figure 2, the workpiece 1, which is provided with the protrusion 44a, can hardly come into contact with the pallet 2 and jigs, making it difficult to cool the solder 43.

[0035] <Summary of Embodiment 3> In contrast, in this embodiment 3, the gas circulation mechanism 30 can blow cooling air onto the workpiece 1, so the temperature can be efficiently reduced and shrinkage cavities in the solder layer can be reduced. In particular, in the case of a workpiece 1 provided with protrusions 44a as shown in Figure 2, the area to which the cooling air is applied is large, so the temperature of the solder 43 can be efficiently lowered and shrinkage cavities in the solder layer can be reduced.

[0036] <Variation> In Embodiment 1, the pressurized cooling section, which pressurizes the inside of chambers 10a and 10b to a pressure higher than atmospheric pressure and cools and solidifies the solder 43 inside chambers 10a and 10b, was described as the gas introduction section 11, but it is not limited to this. For example, the pressurized cooling section may be configured to pressurize chambers 10a and 10b by pressing them against the pallet 2 while maintaining the hermetically sealed chambers 10a and 10b, and to cool them with the gas circulation mechanism 30 of Embodiment 3.

[0037] Furthermore, it is possible to freely combine each embodiment and each variation, and to modify or omit each embodiment and each variation as appropriate.

[0038] The various aspects of this disclosure are summarized below as an appendix.

[0039] (Note 1) A chamber that hermetically seals the area around the workpiece into which the solder has been melted, The chamber is pressurized to a pressure higher than atmospheric pressure, and the solder inside the chamber is cooled and solidified in a pressurized cooling unit. A soldering device equipped with [a specific feature].

[0040] (Note 2) The aforementioned pressurized cooling unit is The soldering apparatus according to Appendix 1, further comprising a gas introduction section for pressurizing the inside of the chamber and introducing a gas for cooling the solder.

[0041] (Note 3) A high-pressure backflow prevention valve connected to the interior of the chamber via a first on / off valve, The interior of the chamber and a normal pressure backflow prevention valve connected via a second on / off valve A soldering apparatus as described in Appendix 1 or Appendix 2, further comprising the above.

[0042] (Note 4) The aforementioned pressurized cooling unit is A soldering apparatus according to any one of the appendices 1 to 3, including a gas circulation mechanism provided inside the chamber. [Explanation of Symbols]

[0043] 1 Workpiece, 10a, 10b Chambers, 11 Gas inlet, 20 First on / off valve, 21 High-pressure backflow prevention valve, 22 Second on / off valve, 23 Normal-pressure backflow prevention valve, 30 Gas circulation mechanism, 43 Solder, 51 Soldering device.

Claims

1. a chamber for hermetically sealing the periphery of the workpiece in which the solder is melted; a pressurized cooling unit that pressurizes the inside of the chamber at a pressure higher than atmospheric pressure and cools and solidifies the solder in the chamber; A soldering apparatus comprising:

2. 2. The soldering apparatus according to claim 1, The pressurized cooling section includes: a gas inlet for injecting a gas that pressurizes the interior of the chamber and cools the solder;

3. The soldering apparatus according to claim 1 or 2, a high-pressure check valve connected to the interior of the chamber via a first opening / closing valve; a normal pressure check valve connected to the interior of the chamber via a second opening / closing valve; The soldering apparatus further comprises:

4. The soldering apparatus according to claim 1 or 2, The pressurized cooling section includes: A soldering apparatus including a gas circulation mechanism disposed within the interior of the chamber.

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