Refuse diffusion prevention component installed in spot solder device

Abstract

To provide a refuse diffusion prevention component installed in a spot solder device, which can prevent a solder refuse, a solder oxide or the like from reaching a substrate, and the spot solder device.SOLUTION: This refuse diffusion prevention component is installed in a spot solder device for soldering a desired place of a substrate discharging a necessary small amount of molten solder from the upper end of a nozzle and bringing it into contact with the substrate, a space around the nozzle being filled with an atmosphere of an inactive gas. The refuse diffusion prevention component comprises: a pedestal provided with a through-hole through which the nozzle is inserted on the center; a cylinder erected on the pedestal so as to surround the outer periphery of the nozzle, the upper end of the cylinder being provided at a position lower than the upper end of the nozzle; and gas distribution means for distributing the inactive gas so as to form an upflow in a space around the cylinder and then a space around the nozzle. The spot solder device comprises this component.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a part for preventing diffusion of residues which is provided in a local soldering apparatus for performing small amounts of soldering on a desired portion of a board over a relatively small area, and to a local soldering apparatus provided with said part. [Background technology]

[0002] Conventional soldering devices have a disadvantage in that the molten solder is easily oxidized by contact with the air because the molten solder is jetted from a nozzle onto the entire back surface of the board. In particular, so-called lead-free solder, which is used instead of conventional lead-containing solder, is easily oxidized by oxygen in the air and is easily formed into solder residue called dross because it is a lead-free composition and used at higher temperatures. Therefore, when soldering is performed using lead-free solder with a conventional soldering device, there is a problem that the defects caused by the oxidation of the solder become significant.

[0003] In response to this, local soldering devices have been proposed that perform soldering by locally contacting a small amount of molten solder with a desired portion of a board. However, conventional local soldering devices do not take into consideration maintaining the temperature of the molten solder over the entire transfer path from when it is stored in the solder bath until it comes into contact with the board.

[0004] In the local soldering device of Patent Document 1, the transport path from the solder bath through the nozzle to contact with the board is substantially sealed except for the nozzle opening, and the sealed internal space, particularly the space outside the nozzle, is filled with high-temperature inert gas, thereby adopting a structure that prevents temperature drop over the entire solder transport path from when the solder is stored in the solder bath to when it comes into contact with the board. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2009-101395 Summary of the Invention [Problem to be solved by the invention]

[0006] In the local soldering device of Patent Document 1, an inert gas is introduced into a heat-retaining chamber to be heated, and then the gas comes into contact with the upper surface (solder surface) of the molten solder in the solder bath, and then rises along the outer periphery of the solder tower and nozzle, until it reaches the upper end of the nozzle. With this structure, it is possible to prevent the nozzle temperature from dropping. However, the local soldering device of Patent Document 1 has a risk of causing the diffusion of solder residue or solder oxides, etc., when the inert gas flowing into the heat-retaining chamber hits the solder surface, and therefore further improvements in the means for suppressing the diffusion of such solder residue or solder oxides, etc. are required. [Means for solving the problem]

[0007] The present invention is characterized in that a component is added to the local soldering device to minimize the blowing of inert gas onto the solder surface when the inert gas is flowing in, and to suppress the generation and diffusion of solder residue or solder oxides, etc. That is, the present invention is [1] The space around the nozzle is filled with an inert gas atmosphere. A small amount of molten solder is discharged from the top of the nozzle and brought into contact with the board. A part for preventing the diffusion of scum that is provided in a local soldering device for soldering a desired portion of a board, comprising: A base having a through hole in the center through which the nozzle passes; a cylinder provided on the base so as to surround an outer periphery of the nozzle, the upper end of the cylinder being located lower than the upper end of the nozzle; and an upward flow forming means for circulating an inert gas so as to form an upward flow that flows into the space around the cylinder and then into the space around the nozzle. [2] A local soldering device equipped with the slag diffusion prevention component according to [1], A solder tank equipped with a heater for storing molten solder; a cover member for covering an upper portion of the solder bath, the cover member having a through hole in the center; a solder tower having a nozzle at an upper portion thereof, a lower portion of the tower being immersed in the molten solder in the solder bath, and the nozzle being erected through the through hole; a heat-retaining chamber having an opening in the center, positioned above the through hole, and covering the outer periphery of the cylinder; A heater member for heating the inside of the heat-retaining chamber; a gas flow means for flowing an inert gas into the heat-retaining chamber, forming an upward flow into the space around the cylinder and then into the space around the nozzle, and then flowing the inert gas out through a gap between the nozzle and the cap; and a solder pressure-feeding means for discharging the molten solder in the solder bath from the upper end of the nozzle through the inside of the solder tower. [3] The local soldering apparatus according to [2], wherein the molten solder is lead-free solder, the inert gas is nitrogen gas, and the heater member is capable of heating the internal atmosphere of the heat-retaining chamber to 250°C to 400°C. Effect of the Invention

[0008] The residue diffusion prevention component of the present invention has the effect of suppressing the generation of solder residue or solder oxides near the solder surface, containing them within the solder bath, and preventing them from reaching the board via the flow of inert gas. The local soldering device equipped with the dregs diffusion prevention component of the present invention has the effect of suppressing the generation of solder dregs or solder oxides near the solder surface, containing them within the solder bath and preventing them from reaching the board via the flow of inert gas. In the present invention, if the molten solder is lead-free solder, the inert gas is nitrogen gas, and the heater member is capable of heating the internal atmosphere of the heat-retaining chamber to 250°C to 400°C, a local soldering device using lead-free solder has the effect of reducing soldering defects. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view of a local soldering apparatus according to the present invention. [Diagram 2] FIG. 2 is a cross-sectional view taken along line AA in FIG. [Diagram 3] FIG. 3 is an exploded view of the local soldering device of the present invention. [Figure 4] FIG. 4 is a bottom view of the gas diffusion prevention part of the present invention. BEST MODE FOR CARRYING OUT THEINVENTION

[0010] When soldering with lead-free solder, it is necessary to keep the following points in mind. First, as mentioned above, lead-free solder is prone to being oxidized by oxygen in the outside air, forming dross that causes soldering defects. Second, because lead-free solder has a relatively high melting point (approximately 220°C), its viscosity easily increases when the temperature drops. The increase in viscosity makes it difficult for the molten solder to be discharged smoothly, causing soldering defects. Third, solder residue and solder particles near the solder surface of the solder bath can easily become oxidized. The aim is to contain the oxides of solder within the solder bath and prevent them from reaching the board. In order to prevent these problems from occurring, the local soldering device of the present invention has a structure in which the solder transfer section from the solder bath to the nozzle opening is entirely sealed, the sealed internal space is filled with high-temperature inert gas, and a residue diffusion prevention component is installed so that part of the inert gas flow path does not pass through the solder surface. The structure of the local soldering device of the present invention equipped with a residue diffusion prevention component will be described in more detail below.

[0011] The local soldering device of the present invention is a soldering device that discharges a required amount of molten solder from the upper end of a nozzle and brings it into contact with the board to solder a desired location on the board, and is particularly suitable for soldering using lead-free solder. This local soldering device is equipped with a solder bath with a heater, a cover member for the upper part of the solder bath, a solder tower, a nozzle, a flow duct, a heat-retaining chamber, a heater member in the heat-retaining chamber, a cover, a cap, a part for preventing the diffusion of residue, a gas distribution means, and a solder pressure-feeding means.

[0012] The solder bath with heater is equipped with a heater on its bottom and / or side to keep the solder in a molten state, and can be heated to about 250°C to about 300°C, which is suitable for soldering using lead-free solder. In addition, the capacity and dimensions of the solder bath in the present invention can be significantly smaller than those of the solder baths of conventional jet soldering devices. This means that the dimensions of the entire device are smaller, the installation area required is smaller, and it is easier to move. The cover member on the top of the solder bath and the base of the scum diffusion prevention part close the top of the heater-equipped solder bath. The shape of the cover member can be flat such as a plate or a shape with curved parts, but unless the closed solder bath is structured to be completely isolated from the atmosphere, it must be structured to prevent the inflow of air.

[0013] The soldering tower is equipped with a cylindrical nozzle at the top, while the lower part of the soldering tower is installed so that it is immersed in the molten solder in the solder bath. The soldering tower is installed so that the nozzle passes through a through hole in the cover member and the inside of the slag diffusion prevention part. The nozzle is provided at the top of the soldering tower and constitutes a part of the soldering tower, and discharges solder from its upper end to contact the board. The nozzle is shaped like a thin cylinder, so that the discharged molten solder contacts only the desired part of the board, and at the same time, it is more reliable to prevent contact with the surrounding electronic components that do not need to be soldered. In this respect, the shape of the hole at the upper end of the nozzle can be circular, as well as elliptical or polygonal (square, rectangular, hexagonal, etc.). In addition, the nozzle and the soldering tower can be provided with a nozzle groove or the like that smoothly returns the excess solder after discharge to the solder bath.

[0014] The flow duct is a rectangular parallelepiped with an open bottom and a circular opening on the top for connecting the solder tower and the impeller shaft, and is attached to the solder tank. The solder tower and fixture are attached to the flow duct. In addition, a part for preventing the diffusion of scum is installed so as to surround the outer periphery of the solder tower attached to the flow duct. The heat-retaining chamber has an opening in the center, and the upper end of the nozzle protrudes from the opening. The heat-retaining chamber is structured to cover the nozzle above the through hole and the part for preventing diffusion of residue. By flowing an inert gas into the heat-retaining chamber, the heat-retaining chamber is filled with the inert gas, and the inside of the heat-retaining chamber is made into a space that is substantially isolated from the atmosphere. Although the above-mentioned case has been described in which the lid member and the heat-retaining chamber are separate, the lid member and the heat-retaining chamber may be integrated into one structure. In this case, the structure is called a heat-retaining chamber with a lid member or a heat-retaining chamber. The heater member in the heat-retaining chamber heats the inert gas filling the space inside the heat-retaining chamber and reduces the temperature drop of the solder bath. The heater member heats the solder bath to a required temperature that does not cause a temperature drop of the molten solder that has flowed into the nozzle. The heater member is preferably a member that prevents the solder from spreading. The heating coil is wound around the anti-spray component and the nozzle. In this embodiment, the anti-spray component and the outer periphery of the nozzle are heated from all directions, which is particularly convenient for preferentially heating the nozzle. Moreover, since the heating coil in this embodiment does not directly contact the outer periphery of the nozzle, the nozzle is not heated more than necessary. On the other hand, since it is not too far from the outer periphery of the nozzle, the effect of heating the nozzle is not lost. The heater member also heats the transfer path of the molten solder, in which the molten solder is pumped from the sealed solder bath to the nozzle and then discharged from the upper end of the nozzle toward the board, so oxidation and a drop in temperature of the molten solder can be effectively prevented.

[0015] Here, the upper end of the nozzle protruding from the opening of the heat-retaining chamber must be long enough to ensure that the molten solder discharged from the upper end of the nozzle can reliably contact and solder the desired location on the board. However, if the length of the protruding upper end of the nozzle is too long, it will come into direct contact with the low-temperature air, causing a drop in temperature of the molten solder and an increase in viscosity, so the upper end of the nozzle is set to as short a length as possible. The opening of the heat-retaining chamber is set to a size that provides a suitable gap between its inner peripheral wall and the outer surface of the upper end of the nozzle to allow the inert gas inside the heat-retaining chamber to be exhausted. In other words, the gap is adjusted to a size that prevents air from flowing into the heat-retaining chamber, while at the same time not disturbing the molten solder discharged from the upper end of the nozzle.

[0016] The cover covers the heat-retaining chamber, further retains the heat of the heat-retaining chamber, and is fixed to the lid member and also fixes the cap. The cap is a conical tube that narrows the flow path of the inert gas flowing out of the heat-retaining chamber, effectively heating the top of the nozzle protruding from the heat-retaining chamber. The opening at the top of the cap is set to a size that provides a suitable gap between the opening and the outer surface of the upper end of the protruding nozzle to allow the inert gas to be discharged. In other words, the gap is adjusted to a size that prevents air from flowing into the cap, while at the same time not disturbing the molten solder discharged from the upper end of the nozzle. The scum diffusion prevention component is composed of a tube that protrudes the upper end of the nozzle and is arranged around the nozzle without contacting the nozzle, and a base that has a through hole for the nozzle and on which the tube is installed. The inside of the tube can be larger than the through hole provided in the center of the base, but it is preferable to make it the same shape as the through hole. Therefore, the structure is such that the tube is attached to the base in appearance. The scum diffusion prevention component is installed so as to surround the outer periphery of the solder tower. Then, the cover member and the heat retention chamber are attached to the solder bath by passing the tube of the scum diffusion prevention component through the through hole of the cover member. The through hole in the center of the base may be rectangular, but if the outer periphery of the nozzle is circular, it is preferable that it is approximately circular. If the through hole is approximately circular, the tube becomes approximately cylindrical. The scum diffusion prevention component with the tube installed on the base is installed on the top of the solder bath and installed in the heat retention chamber, so as to cover the outer periphery of the nozzle and not to come into contact with the nozzle. In addition, since the part for preventing gas diffusion has the role of transferring the heat of the inert gas flowing in from outside the cylinder to the nozzle inside the cylinder, it is preferable to use a metal material with good thermal conductivity.

[0017] Inert gas flows from an inert gas cylinder or the like through an inert gas inlet pipe into the heat-retaining chamber from the side of the chamber and is heated. The inert gas filling the heat-retaining chamber flows into the side of the waste diffusion prevention component through a side hole at the bottom inside of the heat-retaining chamber, heating the lower part of the nozzle, and rises along the space around the outer periphery (side) of the tube of the waste diffusion prevention component, then flows through the space around the nozzle into the gap between the upper end of the nozzle and the inner wall of the opening of the heat-retaining chamber, and is discharged from the cap opening. The inert gas is discharged from the side hole of the heat-retaining chamber through the opening of the heat-retaining chamber, generating an upward flow of inert gas from the bottom. This makes it possible to more reliably heat the entire waste diffusion prevention component and the nozzle. The upward flow forming means is configured to flow the inert gas from the side hole into the side of the gas diffusion prevention part. This is a means provided in the gas diffusion prevention part that raises the gas diffusion prevention part along the space around the outer periphery (side surface) of the cylinder of the gas diffusion prevention part. The gas flow means, including the above-mentioned upward flow forming means, is a means for causing the inert gas to flow from the inert gas inlet pipe into the heat-retaining chamber and out of the heat-retaining chamber and the cap installed at its upper end, and is a means comprised of the inert gas inlet pipe, the lid member, the heat-retaining chamber, the side hole, the part for preventing diffusion of residue, and the cap. The side holes on the inside lower side of the heat retention chamber are important for bringing the heated inert gas into contact with the residue diffusion prevention component and for maintaining the temperature of the nozzle placed inside the residue diffusion prevention component at a high temperature, and the diameter and number of the side holes are set so that the temperature of the nozzle can be maintained at a high temperature. The number of the side holes is about 4 to 32. The diameters of the side holes may be the same or different. When the nozzle groove is provided, the diameter of some of the side holes can be made larger or smaller than the others, taking into account the flow rate of the inert gas that hits the nozzle groove. The scum diffusion prevention component is a component that is installed to prevent the inert gas from flowing directly into the solder bath and the solder surface, and determines the flow path of the inert gas. The inert gas that flows into the heat-retaining chamber is first heated to a required temperature by a heater member, then passes through a side hole in the heat-retaining chamber, hits the side of the cylinder of the scum diffusion prevention component, rises in the space around the outside (side) of the cylinder of the scum diffusion prevention component, passes through the space around the nozzle, and flows upward toward the top of the opening of the heat-retaining chamber. According to this embodiment, the temperature of the inert gas inside the heat-retaining chamber can be reliably maintained at a required temperature, the temperatures around the scum diffusion prevention component and the nozzle can be reliably maintained, and the temperature of the molten solder until it comes into contact with the board can be more reliably maintained.

[0018] The solder pressure-feeding means discharges the molten solder in the solder bath from the top of the nozzle through the inside of the solder tower. This solder pressure-feeding means usually consists of an impeller, a shaft attached to the impeller, and a power source for rotating the impeller via the shaft. Depending on the length or inner diameter of the nozzle used, the solder pressure-feeding means adjusts the amount of molten solder discharged from the top of the nozzle to the required amount.

[0019] In the present invention, the inert gas is flowed into the chamber from a gas supply source such as a high-pressure cylinder through an inert gas introduction pipe. At this time, the inert gas may be at room temperature or may be preheated to a certain temperature, for example, about 100°C to 200°C. The inert gas flowed into the chamber is finally heated to a temperature in the range of about 250°C to about 400°C by a heater member. If the temperature is within this range, the temperature of the molten solder pressure-fed to the nozzle is sufficiently maintained at a required temperature. On the other hand, it is necessary to avoid the thermal influence on other electronic components on the board during soldering due to overheating of the molten solder. More preferably, the inert gas is heated to about 350°C. Also, the inert gas is flowed into the heat-retaining chamber in a sufficient amount so that the temperature of the molten solder pressure-fed to the nozzle does not decrease. The inflow rate is about 20 liters (L) / min or more, preferably about 20 L / min or more, and more preferably about 50 L / min. In the present invention, the inert gas is a gas that does not oxidize the solder and does not contain oxygen. Examples of the gas include nitrogen gas, helium gas, and argon gas, with nitrogen gas being preferred because it is inexpensive and relatively easy to obtain.

[0020] In a particularly preferred embodiment of the present invention, the molten solder is lead-free solder, the inert gas is nitrogen gas, and the heater member in the heat-retaining chamber is capable of heating the internal atmosphere of the heat-retaining chamber to 250° C. to 400° C. Among these, it is more preferred that the heater member is capable of heating the internal atmosphere of the heat-retaining chamber to approximately 350° C. or higher. EXAMPLES

[0021] The present invention will be described in more detail below with reference to examples. However, the scope of the present invention is not limited to these examples. Non-limiting examples only.

[0022] This embodiment will be described with reference to a local soldering apparatus 1 shown in FIGS. 1 to 3 show a case where the heat-retaining chamber and the lid member are formed of separate members, rather than a heat-retaining chamber with a lid member. The local soldering device 1 is a device that performs soldering on a desired location on a board 13 (indicating a range of positions) using lead-free solder 4. In this local soldering device 1, soldering is performed by discharging molten lead-free solder 4 from the upper end of a nozzle 2 (thin cylinder-shaped; total length approximately 80 cm; outer diameter approximately 3 to 20 mm) and bringing it into contact with a desired location on the board 13. The amount of lead-free solder 4 discharged from the nozzle 2 was adjusted to be sufficient for soldering but not to drip from the nozzle 2. This local soldering device 1 comprises a nozzle 2, a solder tower 3, a solder bath 6, a flow duct 17, a cap 9, a residue diffusion prevention part 21, a cover 12, a heat retention chamber 25, a heater member 26, a gas distribution means 20 and a solder pressure-feeding means 30.

[0023] The solder bath 6 is configured in a box shape with a lid member 15 covering the top and a packing 11. A through hole 16 for passing the nozzle 2 is provided in approximately the center of the lid member 15, but since it is covered by a heat-retaining chamber 25, the lead-free solder 4 in the solder bath 6 is isolated from the atmosphere. A plurality of heaters 7 are provided at the bottom of the solder bath 6, so that the lead-free solder 4 in the solder bath 6 can be maintained at approximately 250°C or higher.

[0024] The nozzle 2 is placed on the upper part of the soldering tower 3, and the upper end of the nozzle 2 protrudes from the heat-retaining chamber 25, the residue diffusion prevention part 21, and further from the cap 9. The soldering tower 3 is attached to a flow duct 17 and has a nozzle 2 thereon. The soldering tower 3 is installed so that the lower part of the tower is immersed in the lead-free solder 4 in the solder bath 6, and the nozzle 2 passes through the through hole 16 of the cover member 15 and the through hole 24 of the base 23 of the residue diffusion prevention part 21 to stand upright. The through hole 16 and the through hole 24 are sized to have a gap between them and the outer periphery of the nozzle 2 so that they do not come into contact with each other. This soldering tower 3 has a structure that tapers from the bottom to the top, so that when the lead-free solder 4 is pumped into the soldering tower 3, the flow pressure increases toward the top, ensuring that the lead-free solder 4 is pumped to the top end of the nozzle 2. A solder tower 3 and a fixture 8 are attached to the flow duct 17. The flow duct 17 is then attached to the solder bath 6 by the fixture 8.

[0025] The heat-retaining chamber 25 is attached to the upper surface of the lid member 15. A substantially circular opening is formed in the center of the heat-retaining chamber 25, and the upper end of the nozzle 2 protrudes from the opening. The heat-retaining chamber 25 covers the nozzle 2 and the residue diffusion prevention part 21 above the lid member 15. The length of the upper end of the nozzle 2 is adjusted to a length that corresponds to the structure of the soldering portion of the board 13, and to a length that maintains the lead-free solder 4 at a temperature (approximately 250°C or higher) that can prevent a significant increase in viscosity when the lead-free solder 4 is pressure-fed to the upper end of the nozzle 2. In addition, the heat-retaining chamber 25 is entirely covered with a cover 12, which further improves the heat-retaining effect of the heat-retaining chamber 25. In this embodiment, in order to further increase the airtightness of the heat-retaining chamber 25, the cover 12 and the cap 9 are used together and attached to cover the periphery of the nozzle 2 (space 14 around the nozzle). The gap between the upper end of the nozzle 2 and the inner peripheral wall of the opening of the heat-retaining chamber 25 and the gap between the upper end of the nozzle 2 and the cap 9 are adjusted to be large so that the discharge of the lead-free solder 4 from the upper end of the nozzle 2 is not disturbed by pressure when the inert gas (nitrogen gas) is discharged, but small so that air can be prevented from flowing into the heat-retaining chamber 25 and the cap 9.

[0026] In this embodiment, a heater member 26 is installed to heat the atmosphere inside the heat-retaining chamber 25. The heater member 26 is provided so as to wrap around the residue diffusion prevention part 21 and the nozzle 2, and is capable of radiating heat from all directions around the nozzle 2, including its outer periphery (space 14 around the nozzle). The heater member 26 is covered above and on the left and right sides by the heat-retaining chamber 25, and its lower part is covered by the lid member 15, so that it is separated from the rest of the inside of the heat-retaining chamber 25. Inert gas (nitrogen gas) flows from a high-pressure cylinder (gas supply means) through an inert gas introduction pipe 10 into the heat-retaining chamber 25 from the side of the heat-retaining chamber 25. The inert gas (nitrogen gas) is first heated to approximately 250 to 400°C by a heater member 26, passes through a side hole 27 of the heat-retaining chamber 25 and hits the side of the tube 22 of the heat-retaining chamber 25, then rises up the side of the tube 22 of the heat-retaining chamber 25 toward the top of the opening of the heat-retaining chamber 25, passes through the space 14 around the nozzle, and flows through the gap in the cap 9 toward the upper end of the nozzle 2 (see the arrow in FIG. 1). When the inert gas (nitrogen gas) rises up the side of the heat-retaining chamber 25, the nozzle 2 inside the heat-retaining chamber 25 can be more reliably heated. The upward flow (upward flow forming means) 28 is a means provided in the gas diffusion prevention part 21 for causing the inert gas to flow from the lateral hole 27 into the side of the gas diffusion prevention part 21 and then causing the gas to rise along the space around the outer periphery (side surface) of the tube 22 of the gas diffusion prevention part 21. The gas flow means 20, including the above-mentioned upward flow forming means 28, is a means for causing the inert gas to flow from the inert gas inlet pipe 10 into the heat-retaining chamber 25 and out of the heat-retaining chamber 25 and the cap 9 installed at its upper end, and is a means constituted by the inert gas inlet pipe 10, the cover member 15, the heat-retaining chamber 25, the side hole 27, the gas diffusion prevention part 21 and the cap 9.

[0027] The local soldering device 1 also includes a solder pressure-feeding means 30 consisting of an impeller 34 provided in the solder bath 6, a shaft 32 attached to the impeller 34, and a power transmission means 31 for transmitting the driving force of a motor 33 to the shaft 32. The lead-free solder 4 in the solder bath 6 passes through the inside of the solder tower 3 and is discharged from the upper end of the nozzle 2 by the solder pressure-feeding means 30.

[0028] This soldering apparatus 1 can prevent the lead-free solder 4 in the solder bath 6 from coming into contact with oxygen in the air and prevent the formation of dross during local soldering using the lead-free solder 4. Also, the soldering apparatus 1 heats the lead-free solder 4 throughout the entire transfer path from inside the solder bath 6 through the nozzle 2, where it is discharged from the upper end, until it is soldered to the board 13, and can therefore prevent a drop in the temperature of the lead-free solder 4 and an increase in its viscosity. Furthermore, the soldering apparatus 1 does not diffuse solder residue or solder oxides generated in the vicinity of the solder surface 5 of the solder bath 6, so as to allow them to reach the surface of the board 13, effectively preventing soldering defects. [Explanation of symbols]

[0029] 1: Local soldering device 2: Nozzle 3: Solder tower 4: Lead-free solder 5: Solder surface 6: Solder bath 7: Heater 8: Fixture 9: Cap 10: Inert gas inlet pipe 11: Packing 12: Cover 13: Board (position) 14: Space around the nozzle 15: Lid member 16: Through hole 17: Flow duct 20: Gas distribution means 21: Gas diffusion prevention part 22: Cylinder 23: Base 24: Through hole 25: Heat-retaining chamber 26: Heater member 27: Horizontal hole 28: Upward flow (upward flow forming means) 30: Solder pressure-feeding means 31: Power transmission means 32: Shaft 33: Motor 34: Impeller

Claims

1. The space around the nozzle is filled with an inert gas atmosphere. A slag diffusion prevention component that is equipped in a local soldering device for soldering a desired portion of a board by discharging a required amount of molten solder from an upper end of the nozzle and bringing it into contact with the board, A base having a through hole in the center through which the nozzle passes; a cylinder provided on the base so as to surround an outer periphery of the nozzle, the upper end of the cylinder being located lower than the upper end of the nozzle; and an upward flow forming means for circulating an inert gas so as to form an upward flow that flows into the space around the cylinder and then into the space around the nozzle.

2. A local soldering device comprising the scum diffusion prevention component according to claim 1, A solder tank equipped with a heater for storing molten solder; a cover member for covering an upper portion of the solder bath, the cover member having a through hole in the center; a solder tower having a nozzle at an upper portion thereof, a lower portion of the tower being immersed in the molten solder in the solder bath, and the nozzle being erected through the through hole; a heat-retaining chamber having an opening in the center, positioned above the through hole, and covering the outer periphery of the cylinder; A heater member for heating the inside of the heat-retaining chamber; a gas flow means for flowing an inert gas into the heat-retaining chamber, forming an upward flow into the space around the cylinder and then into the space around the nozzle, and then flowing the inert gas out through a gap between the nozzle and the cap; a solder pressure-feeding means for discharging the molten solder in the solder bath from the upper end of the nozzle through the inside of the solder tower.

3. 3. The local soldering apparatus according to claim 2, wherein the molten solder is lead-free solder, the inert gas is nitrogen gas, and the heater member is capable of heating the internal atmosphere of the heat-retaining chamber to 250°C to 400°C.

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