WO1998030351A1

WO1998030351A1 - Soldering method and soldering iron

Info

Publication number: WO1998030351A1
Application number: PCT/JP1997/001528
Authority: WO
Inventors: Akio Mitumoto; Kensei Matubara
Original assignee: Kabushikigaisha Taiseikaken
Priority date: 1997-01-07
Filing date: 1997-05-06
Publication date: 1998-07-16
Also published as: WO1998030352A1; JP2000000657A

Abstract

When a soldering iron is used to subject a work to soldering while blowing a high temperature gas flow against that portion of the work, which is to be soldered, a tip end of the soldering iron jets a main heating gas flow of a sufficiently high temperature to melt and soften solder, a preheating gas flow of a temperature, which is lower than that of the main heating gas flow but sufficiently high to preheat the solder, is jetted surrounding the main heating gas flow, the preheating gas flow is blown against that portion of the work, which is to be soldered, to preheat the portion, and then the main heating gas flow is blown against that portion of the work, which is to be soldered and has been preheated, to effect soldering in an atmosphere surrounded by the preheating gas flow.

Description

One i one

Akeito IH

Soldering method and soldering iron

Technical field

The present invention relates to a soldering method and a soldering iron, for example, which enable high-quality soldering of electronic components.

Background art

For example, when assembling an electronic device, various electronic components are often soldered to an electronic substrate using a soldering iron.

For this type of soldering iron, a method is widely used in which the tip chip heated by heating or the like is brought into contact with the land of the electronic board to melt the solder, and the tip chip is separated to solidify the solder. .

On the other hand, as shown in Fig. 9, an air passage was formed in the soldering iron 100, a heater 101 was built in, and a stainless steel or brass nozzle 102 was attached to the tip, and the A non-contact type soldering iron which is soldered by blowing air has also been proposed.

In the conventional contact-type soldering method, the tip is brought into contact with the soldering part, so that the tip is subjected to thermal stress due to the heat cycle, and tin diffusion and erosion due to flux occur. As a result, the life of the tip was short, and it was necessary to replace it about 40,000 to 50,000 times in order to secure soldering accuracy. Also, since the advanced chip comes into direct contact with the electronic substrate and electronic components, leakage current, noise, harmonics, static electricity, etc. are transmitted from the advanced chip to the electronic substrate and electronic components, and there is a concern that the electrical characteristics of the product may be degraded. I was

On the other hand, with the conventional non-contact type soldering iron, although the above-mentioned problems do not occur, high-temperature air hits the work and then scatters around, causing spots where heat is needed. It is not practical because it takes 4 to 5 seconds to solder, and it is used for removing (reworking) soldered electronic components. Disclosure of the invention

An object of the present invention is to provide a soldering method that can eliminate the need for replacement of a tip chip and that can perform high-quality soldering of electronic components and the like in view of such problems.

Therefore, the non-contact soldering method according to the present invention uses a soldering iron, and melts and softens the solder from the tip of the soldering iron when soldering the work by blowing a high-temperature gas flow onto the soldering portion of the work. And a high-temperature main heating gas flow that is high enough to blow out the surroundings of the main heating gas flow. The main heating gas flow is blown to the soldering portion of the preheated work while the preheating gas flow is sprayed to the soldering portion of the work to perform soldering in an atmosphere surrounded by the preheating gas flow. It is characterized by doing so.

The gas stream is preferably a high concentration of inert gas. This is because an inert gas such as nitrogen gas is preferable in consideration of the effect of O ₂ in air on soldering quality. The heating element only needs to generate heat, and a nichrome wire heater, a ceramic heater, a high-frequency heater, a medium-frequency heater, a low-frequency heater, an infrared heater, a plasma heating element, an ultrasonic heating element, an elema heating element, or the like can be used. .

One of the features of the present invention is that a high-temperature internal / external dual gas flow is formed, preheated by an external gas flow, and soldered by an internal gas flow in an atmosphere surrounded by an external gas flow. It is in. As a result, the heat of the gas flow inside does not scatter to the surroundings, soldering can be performed in a short time in a non-contact manner, and the effects of leakage current, noise, and harmonics on products can be eliminated. However, with regard to static electricity, the friction of the gas flow, especially when the gas flow is ejected at high speed, charges the gas flow, and there is still concern about the electrical effects on the product. Therefore, the main ejection pressure of the heating gas flow and the preheating gas stream charged gas flow range such that the extent that no fear of electrical influence, specifically of 0. l~2 kgf / cm ² · G The pressure is preferably set. In order to achieve a dense and well-soldered solder, soldering should be performed in an atmosphere where the adhered molten solder can be slowly cooled with moderate temperature characteristics, and immediately cooled immediately before the start of solidification in an atmosphere below room temperature. Is essential. In the present invention, the gas flow is made into an inner / outer double, preheated by the outer preheating gas flow, soldered by the inner main heating gas flow, and then slowly cooled to just before the start of solidification by the outer preheating gas flow to room temperature. Exposure to the following atmosphere allows rapid cooling. When the present invention is applied to the soldering of electronic components, the temperature of the main heating gas flow is 100 to 100 ° C., preferably 250 to 600 ° C., and the temperature of the preheating gas flow is It is preferable to jet the gas at a lower temperature than the high-temperature gas flow, for example, at a flow rate of 100 to 20 (TC, 0.5 to 2 liters / minute).

Rapid cooling immediately before the start of solidification of the molten solder may be performed by exposing it to the atmosphere.However, the molten solder releases latent heat upon solidification, and simultaneously dissolves 0 ₂ , H ₂ , CO, etc. in the atmosphere. Oxidation of the solder immediately before solidification causes oxidation and porosity, and is the largest factor in the generation of bridges, knuckles, and smears. Therefore, the ambient may be a low-temperature nitrogen gas atmosphere at room temperature or lower. The low-temperature nitrogen gas atmosphere is set to room temperature, specifically, a temperature of 25 ° C. or lower, but it is preferable to secure a quenching effect. For example, it may be set to a temperature of from 120 ° C. to 130 ° C. Also, when the work surface is exposed to a low-temperature nitrogen gas atmosphere, the molten solder is rapidly cooled from the front side. However, when the low-temperature nitrogen gas is blown on the back side of the workpiece and the work is also rapidly cooled from the back side, the rapid cooling effect is promoted. It is preferable because a finer rapidly solidified structure can be obtained.

Further, according to the present invention, it is possible to provide a soldering iron used in the above-mentioned non-contact soldering method.

That is, the non-contact type soldering iron according to the present invention is a non-contact type soldering iron for performing soldering by blowing a high-temperature gas flow to a soldering portion of a work. A first nozzle, and a second nozzle that covers and opens the outside of the first nozzle, while a heating element is built in the iron body, and a periphery of the heating element is provided. Alternatively, a main heating gas flow generation chamber is formed in communication with the first nozzle, and a preheating gas flow generation chamber is formed around the main heating gas flow generation chamber. A chamber is formed in communication with the two nozzles, and the iron body is provided with a gas supply passage for supplying gas to the main heating gas flow generation chamber and the preheating gas flow generation chamber. The heating generates a high-temperature main heating gas flow high enough to melt-soften the solder and is ejected from the first nozzle, and heating by convection heat and / or radiant heat from the main heating gas flow generation chamber or a heating element. As a result, a preheating gas flow having a lower temperature than the main heating gas flow and a temperature sufficient to preheat the solder is generated, and is ejected from the second nozzle around the main heating gas flow. It is characterized by.

The main heating gas flow generation chamber 1 is preferably formed around the heating element from the viewpoint of manufacturing simplicity, but may be formed inside the heating element. The shape of the nozzle is not particularly limited, but it is preferable to use, for example, a diverge nozzle, since it is better to jet the gas stream at a higher speed. The preheating gas flow may be ejected straight around the main heating gas flow, but a spiral fin and a spiral groove are formed on the inner surface of the preheating gas flow generation chamber 1 so that the preheating gas flow is formed in a spiral shape. By turning, the air in the space surrounded by the preheating gas flow is sucked out, and the main heating gas flow is jetted in that state, so that the soldering efficiency of the main heating gas flow can be improved. The positional relationship between the tips of the first and second nozzles may be such that the tip of the second nozzle projects beyond the tip of the first nozzle, or the positional relationship may be reversed. The latter is preferable when the element of the work is small, especially when the element has an ultra fine pitch, for example, when soldering electronic components.

Incidentally, even if the ejection pressure of the main heating gas fluid and the preheating gas fluid is appropriately set as described above, the charging of the gas flow may still remain. Therefore, the main body of the trowel is grounded, and a negative charge is electrostatically induced inside the main heating gas flow generation chamber and the preheating gas flow generation chamber to remove the positive charges of the main heating gas flow and the preheating gas flow. It is better to be able to do it.

In the present invention, since the soldering portion of the work is preheated by the preheating gas flow, even if the tip is brought into contact with the soldering portion, the temperature drop of the tip is small and the tip is preheated. As a result of being heated by the gas flow and quickly raising the temperature, Thermal stress of the chip can be reduced.

That is, according to the present invention, when soldering a soldering portion of a work using a soldering iron, the temperature of the tip of the soldering iron is lower than that of the above-mentioned tip and sufficient for preheating the solder. The preheated gas flow is blown around the above-mentioned tip, and the preheated gas flow is sprayed onto the soldering part of the work to preheat the work. Then, the soldering part of the preheated work is made into the preheated gas flow by the tip. A contact type soldering method characterized in that the soldering is performed in an enclosed atmosphere.

In this case, the preheated gas flow reduces the heat cycle of the tip and quickly returns the temperature-reduced tip to a predetermined temperature. It is preferable to use a high temperature, but there is a concern about the thermal effect on the work and elements (for example, electronic elements) near the soldering site. Therefore, a low-temperature gas flow, which is lower than the preheating gas flow, is sprayed around the preheating gas flow from the tip of the soldering iron. May be protected from the heat of the preheated gas stream with a low temperature gas stream. Further, according to the present invention, it is possible to provide a soldering iron used in the above-mentioned contact-type soldering method.

That is, according to the present invention, in a soldering iron in which the tip can be heated by the heat generated by the heating element built in the iron body, the tip of the tip is placed around the heating element. A preheating gas flow generation chamber is formed to open to the surroundings, and the heat generated by the heating element also generates a preheating gas flow at a low temperature and at a temperature sufficient to preheat the solder. It is possible to provide a contact-type soldering iron characterized in that it is ejected to the surroundings.

In this case, a low-temperature gas flow generation chamber 1 is formed around the preheating gas flow generation chamber and its front end is opened around the front end opening of the preheating gas flow, and the convection heat from the preheating gas flow generation chamber 1 is formed. Alternatively, a structure may be adopted in which a low-temperature gas flow lower than the preheating gas flow is generated by heating with z or radiant heat and is ejected around the preheating gas flow. Also, if the above-mentioned contact-type soldering iron structure is used, when soldering with a soldering robot or an automatic soldering machine, a high-temperature inert gas such as a high-temperature nitrogen gas is blown to the soldering portion, It is possible to provide an inert gas purging device suitable for protecting the soldering portion from the atmosphere and preheating.

That is, the inert gas purging apparatus according to the present invention has a shape of a soldering iron as a whole, has a built-in heating element, and a heating element is attached to a tip portion of the heating element. While the heating element can be heated, a preheating gas flow generation chamber is formed around the heating element by opening its front end side around the front end of the heat holding element, and the preheating gas flow generation chamber is formed. High-temperature gas flow is generated by the radiant heat and is ejected forward.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a sectional view showing a principal part of a first embodiment of a soldering iron according to the present invention. FIG. 2 is a sectional view taken along the line II. FIG. 3 is a view for explaining a soldering method using the above-mentioned soldering iron. FIG. 4 is a sectional view showing a first modified example of the soldering iron. FIG. 5 is a sectional view showing a second modification of the above-mentioned soldering iron. FIG. 6 is a sectional view showing a principal part of a second embodiment of the soldering iron according to the present invention. FIG. 7 is a sectional view showing a principal part of a third embodiment of the soldering iron according to the present invention. FIG. 8 is a perspective view showing the holder 35 in the soldering iron of FIG. FIG. 9 is a configuration diagram showing a conventional non-contact soldering iron. FIG. 10 is a view showing a preferred embodiment of the inert gas purge apparatus according to the present invention.

Description of the preferred embodiment

Hereinafter, the present invention will be described in detail based on specific examples shown in the drawings. 1 and 2 show a preferred embodiment of a non-contact soldering iron according to the present invention. The rear end of the iron body 11 is attached to the tip of the iron base 10 by means of a screw or the like, and the iron body 11 is connected to the inner and outer double stainless steel cylinders 12 and 13. The inner stainless steel tube 13 is supported by a spacer piece (not shown) on the inner surface of the outer stainless steel tube 12 including a central rod-shaped alumina ceramic heater (heating element) 14. The heater 14 is supported on the inner surface of the inner stainless steel tube 13 by a metal cover 15, and a plate-shaped spacer 16 is formed at the rear end of the cover 15. Main heating gas flow generation chamber 17 that generates a main heating gas flow high enough to melt and soften the solder by heating the heater between heater 5 and inner stainless steel cylinder 13, inner and outer stainless steel cylinders 12, 1 Between 3 is a preheating gas flow generation chamber 18 that generates a preheating gas flow at a temperature lower than the main heating gas flow and at a temperature sufficient to preheat the solder by heating by convection heat and / or radiant heat. .

Also, a first nozzle 19 made of molybdenum is fitted to the tip of the inner stainless steel cylinder 13 with a force, and the first nozzle 19 is protruded from an insertion hole of the tip wall of the outer stainless steel cylinder 12, A second nozzle 20 that covers the entire outer periphery of the first nozzle 19 is externally fitted to the tip of the outer stainless steel cylinder 12.

Further, the iron base 10 has a hollow shape and the inside is a gas supply passage 21. A first gas flow port 22 is provided at the rear end of the iron body 11 with a cover 15. A second gas flow port 23 is formed in the plate-shaped sensor part 16 of the second heat pump, and a third gas flow port 24 is formed at the tip of the cover 15 to form the main heating gas flow generation chamber 1 1. The main heating gas flow generated in 7 is guided toward the first nozzle 19. In addition, the gas supply passage 21 may be constituted by a hose or the like supported outside the iron base 10. Further, a fourth gas flow port 25 is formed in the inner stainless steel cylinder 13 behind the cover 15, and a fifth gas flow port 26 is formed at the tip of the outer stainless steel cylinder 12, and a preheat gas flow is generated. The preheated gas stream generated in the chamber 18 is guided toward the second nozzle 20.

At the end of the heater 14, a sensor 17 for detecting the temperature of the main heating gas flow 30 and performing control is mounted, and although not shown, a stainless steel cylinder 1 2 And 13 are connected to ground.

Next, the soldering method will be described. When soldering is performed in a non-contact manner using the soldering iron of this example, first, the heater 14 is energized, and nitrogen gas is supplied to the gas supply passage 21 in the base 10. This nitrogen gas has a predetermined temperature, for example, 4 It may be preheated to 0-50 ° C. Then, the nitrogen gas is guided to the main heating gas flow generation chamber 17 via the gas flow ports 22 and 23, and is heated to 250 to 600 ° C. by the heating heater 14 to be heated to the main heating gas. A stream 30 is generated, and the main heated gas stream 30 is ejected from the first nozzle 19 via the gas flow port 24. The ejection amount of the main heating gas stream 30 is set to 0.5 to 2.0 liters, and the ejection pressure is set to 0.1 to 2.0 kgf / cm ² · G.

At the same time, a part of the nitrogen gas is respectively guided to the preheating gas flow generation chamber 18 through the gas flow port 25, and the convection of the high-temperature nitrogen gas in the main heating gas flow generation chamber 17 and the heating heater 14 The preheated gas stream 31 is generated by being heated to 100 to 200 ° C by the radiant heat of the second nozzle 20 through the gas flow port 26 and flows around the main heated gas stream 30. Spouted over. The ejection volume of the preheated gas stream 31 is set to 0.5 to 2.0 liters Z, and the ejection pressure is set to 0.1 to 2.0 kgf / cm ² · G.

When the preparation is completed, first, a preheating gas flow 31 is blown onto the soldering portion W of the substrate to preheat the soldering portion W, and then the main heating gas flow 30 is blown. 0 is sprayed onto the soldering site W with its surroundings covered by the preheating gas flow 31 as shown in Fig. 3, and it does not scatter around as it is in the past, so the solder melts immediately . Thereafter, the molten solder is slowly cooled by a preheating gas stream 31 until just before the start of solidification, and then rapidly cooled by being exposed to the atmosphere.

According to the experiments conducted by the inventors of the present invention, it took 4 to 5 seconds for the conventional non-contact soldering iron to complete the soldering, whereas the non-contact soldering iron of the present example required 1 second. It was confirmed that the soldering could be completed in a certain degree. Therefore, the non-contact type soldering of the present embodiment can be practically adopted instead of the conventional soldering port bot / soldering in the automatic soldering machine.

Also, when the heat of the molten solder is rapidly absorbed into the surroundings, the molten solder is rapidly cooled as a whole, and fine quenched crystals, fine columnar crystals, and fine free crystals are formed. Grain boundaries containing impurities and gases are likely to be generated parallel to the columns, and free crystals are flux Gas and impurity gas are easy to contain. On the other hand, since the main heating gas flow 30 and the preheating gas flow 31 of appropriate pressure are blown to the molten solder, the solder and flux do not flow out of the soldering portion W, and the molten solder is applied. Pressurizes and releases gas, eliminating bubbles and gas holes. In addition, the dendrite can be filled with the molten solder by the pressurization due to the pressurization, thereby preventing microporosity and macroporosity (porosity), resulting in a dense crystal structure.

Therefore, the whole of the molten solder is rapidly cooled, so that the distance between the liquidus and solidus of the molten solder is substantially reduced, and a pressurizing effect is exerted, and macro-segregation (Pb, Sn, etc.) The dendritic crystals, layered structure, nucleated structure, etc., of the birefringence are reduced, and a solidified solder having a fine crystal structure with few impurities and gas can be obtained.

In addition, since the ejection pressure of the main heating gas flow 30 and the preheating gas flow 31 is set appropriately, charging due to gas friction is unlikely to occur, and since the iron body 11 is grounded, Even if 30 and 31 are positively charged, the main heating gas flow generation chamber — 17 and the preheating gas flow generation chamber-electrostatically induce negative charges inside the chamber 18 to generate the main heating gas flow 30 and preheating gas As a result, the positive charge of the flow 31 can be removed, so that the possibility of electrostatic breakdown at the soldering site W can be reliably eliminated.

FIG. 4 shows a first modification of the above embodiment. In this example, the tip of the second nozzle 20 protrudes forward from the tip of the first nozzle 19, and the inner stainless steel tube 13 is made of beryllium copper, chromium copper, or another alloy having good heat conductivity. The inner alloy tube 13 and the first nozzle 19 are formed integrally with the inner alloy tube 13, and the second nozzle 20 and the outer stainless steel tube 12 are formed integrally. The first nozzle 19 employs a divergent nozzle structure whose inner surface expands in an arc shape in cross section. Dimensionally, the inner diameter of the tip of the first nozzle 19 is set to 0.1 to 0.5 mm, the inner diameter of the second nozzle 20 is set to 0.5 to 4.0 mm, and A flat surface 20a of l to 2 mm is formed on the inner surface of the tip portion of the nozzle 20 to stabilize the preheating gas flow.

In this example, a divergent nozzle is used for the first nozzle 19, so that a high-speed main heating gas flow can be obtained by the structure, and the tip of the second nozzle 20 is Because it is more protruding than that of the first nozzle 19, the preheating gas flow and the high-speed main heating gas flow accelerate each other, and the higher-speed main heating gas flow and the higher-speed preheating gas flow can get. As a result, even after a certain distance between the tip of the first and second nozzles 19 and 20 and the work soldering site, Thermal decay of the main heating gas flow and the preheating gas flow until reaching the work soldering site is small, and the consumption of nitrogen gas (or air) can be suppressed.

FIG. 5 shows a second modification. In this example, a hollow ceramic heater is used as the heater 14, and a main heating gas flow generation chamber 17 is formed inside the heater 14. A coil-shaped material 17a made of a molybdenum-based alloy or a tungsten-based alloy is housed in the heater 14 to impart a swirl to the main heating gas flow to reduce heat unevenness of the main heating gas flow. ing. A spiral fin or a spiral groove is formed on at least one of the second nozzle 20 and / or the outer surface of the outer cylinder 12 and / or the first nozzle 19 and / or the outer surface of the inner cylinder 13 to impart a swirl to the preheating gas flow. You may do so.

FIG. 6 shows a second embodiment of the present invention. In the figure, the soldering iron main body 30 and the grip part (iron base) 31 and the force, and the iron body 30 are heated over night (for example, a round bar-shaped alumina nitride heater). 3 2 is built in, the tip of the heater 3 2 is inserted into the hole of the tip holder 1 3 3, the tip 3 4 is fixed to the tip of the tip holder 3 3, and the heat generated by the heater 3 2 is the tip 3 The tip 4 is transmitted to the tip 4 and is heated.

The rear end of the heater 32 is inserted and held in the center hole of a holder 35 built in the tip of the grip portion 30, and a temperature sensor (not shown) is attached to the heater 32. Have been. An auxiliary heater for adjusting the temperature of the preheating gas flow may be installed. A plurality of nitrogen gas supply holes are formed in an annular shape in the holder 135, and a tip of a nitrogen gas supply pipe 36 passed through the grip portion 30 is connected to the holder 35, and a heater 3 is provided. A power line 32 a extends rearward in the nitrogen gas supply pipe 36 from the rear end of 2. A first protective cover 37 is fixed to the end of the grip portion 30. The first protective cover 37 covers the periphery of the heater 32 and a predetermined space between the chip holder 33 and the heater. A gap, for example, a gap of l mm extends to the distal end side, and the distal end is opened around the distal end tip 34, thus forming a preheating gas flow generation chamber 38. It is preferable that the tip of the first protective cover 37 is extended to as close to the tip chip 34 as possible, so that it does not touch the work at the time of soldering.

Next, the method of use will be described. When soldering using the soldering iron of this example, first, the heater 32 is energized to heat the tip chip 34 to 280 ° C to 380 ° C, while the soldering iron 32 is heated. The nitrogen gas supply pipe 36 is supplied with nitrogen gas having a pressure of 1.0 to 5.0 kg / cm ² , a flow rate of 4 liter / min, and a purity of 99 to 99.9%. The supply of nitrogen gas may be continuous supply or intermittent supply. Then, the nitrogen gas passing through the preheating gas flow generation chamber 1 38 is heated to 200 ° C. to 25.0 ° C. by the radiant heat of the tip 34 due to the heat generated by the heater 32, and the volume increases. And released as it is. The flow rate and pressure of the nitrogen gas can be adjusted by setting the inner diameter and number of the nitrogen gas supply holes of the holder 35. It is also possible with an external pressure regulator or flow regulator.

When the preparation is completed, first, a preheating gas flow is blown to the soldering part of the board for 2 to 5 seconds to preheat the soldering part (preheating), thereby activating a low residue flux at the soldering part. In addition, the tip 34 may be brought into contact with the soldering portion at the same time as the preheating gas flow is sprayed. In the case under 〇 ₂ concentration 5 ppm or less can be fluxless soldering.

Next, in about 0.3 to 0.8 seconds, the tip 34 is brought into contact with the soldering area and heated to supply the low-residue flux-containing threaded solder, and the soldering area is heated in a preheated gas flow atmosphere. To form a pile of molten solder. Next, the tip 34 is separated from the soldering site, and the molten solder is exposed to the atmosphere of the preheated gas flow, while rapidly cooling by blowing nitrogen gas at room temperature from the back surface of the substrate.

Then, the heat of the molten solder is rapidly absorbed by the surroundings, and the molten solder is rapidly cooled as a whole. As a result, fine quenched crystals, fine columnar crystals, and fine free crystals are formed. Columnar crystal grain boundaries is likely to occur including parallel impurities or gases into crystalline pillar, and the pressure 1 of hot nitrogen gas 6 5 to free crystals of the flux gas and impurity gas. 0-5. To O k gZ cm ² Thus, the molten solder is pressurized and gas is released, so that bubbles and gas holes can be eliminated. In addition, the high-temperature nitrogen gas 65 added allows the dendrites to be filled with the molten solder melt, thereby preventing micro-macroporosity (porosity) and achieving a dense crystal structure. Become.

In addition, the solder flux is preheated to activate the flux and to prevent the flux / solder ball from scattering, so that a smooth and good soldering operation can be performed. Preheating the electronic board before contacting the board, mitigating local and rapid temperature rise (heat shock) of the electronic board and preventing thermal destruction of electronic components, as well as flux, electronic board and supplied solder The wire can also be preheated, so that the hot brittleness of the solder layer can be prevented.

Also, since the solder and flux can be preheated with high-temperature nitrogen gas, the amount of heat stored in the tip of the soldering iron is small, and even if the tip of the chip is extremely fine, sufficient amount of heat can be used for soldering, resulting in low-temperature soldering. Can be achieved. Further, since the soldering iron chip is in a non-oxidizing atmosphere, the chip is prevented from being oxidized, the wettability of the molten solder can be improved, and the chip cleaning is almost unnecessary, so that the chip life can be greatly improved.

FIG. 7 shows a third embodiment of the present invention. In this example, a second protective cover 39 is fixed to the end of the grip portion 30 outside the first protective cover 37, and the first protective bar 39 is a first protective cover 37. Around the end of the first protective cover 37 with a predetermined gap, for example, a gap of 2 mm. Opened to the side, a low-temperature gas flow generation chamber 140 is thus configured. As shown in FIG. 8, a nitrogen gas supply hole is formed in the holder 135 in a double annular shape so that nitrogen gas is also supplied to the low-temperature gas flow generation chamber 140. In this example, soldering is performed in substantially the same manner as in the above-described second embodiment. However, during preheating and during soldering, the substrate and electronic components around the soldering site are removed from the low-temperature gas flow generation chamber. Since the substrate is exposed to a low temperature generated at 0, for example, a nitrogen gas atmosphere at room temperature, the surrounding substrates and electronic components can be prevented from being affected by heat.

FIG. 10 shows a preferred embodiment of an inert gas purging apparatus to which the concept of the present invention is applied. The inert gas purging apparatus includes a main body 30 and a grip 31. The main body 30 incorporates a heater (eg, a round bar-shaped alumina nitride heater) 32, and the tip of the heater 32 is Heat retaining member made of copper alloy with good thermal conductivity (heat retaining member) 33 Inserted into the hole of 33, heat generated by heater 32 is transmitted to heat retaining member 33, and heat retaining member 33 is heated. It is supposed to be.

The rear end of the heater 32 is inserted and held in the center hole of a holder 35 built in the tip of the grip portion 30, and a temperature sensor 39 is attached to the heater 32. I have. A plurality of nitrogen gas supply holes are formed in an annular shape in the holder 135, and a tip of a nitrogen gas supply pipe 36 passed through the grip portion 30 is connected to the holder 35, and a heater 3 is provided. A power line 32 a extends rearward in the nitrogen gas supply pipe 36 from the rear end of 2.

A first protective cover 37 is fixed to the tip of the grip portion 30. The first protective cover 37 covers the heater 32 and a space between the first protective cover 37 and the heat retaining member 33. A predetermined gap, for example, a gap of l mm is extended to the front end side, and the front end is opened to surround the front end of the heat retaining member 33, thereby forming a high temperature gas flow generation chamber 38.

The inert gas purging apparatus of this example is used to spray high-temperature inert gas to the soldering area when soldering with a soldering robot or an automatic soldering machine to protect the soldering area from air and preheat it. Optimal. Industrial applicability

According to the present invention, the inner and outer dual gas flows ejected from the tip of the soldering iron are preheated by the outer preheating gas flow, and then the inner preheating gas is surrounded by the outer preheating gas flow. Since the soldering is performed with the main heating gas flow, the heat of the main heating gas flow blown to the work soldering part does not scatter around and is efficiently transmitted to the work soldering part. Soldering can be performed in a short time without contact, that is, without using a tip.

As a result, it is possible to prevent the deterioration of the electrical characteristics of the product due to the contact of the tip, and to set the ejection pressure of the main heating gas flow and the preheating gas flow appropriately, This can reliably prevent electrification of the product, thereby preventing electrostatic breakdown of electronic components and ensuring the electrical characteristics of the product.

In addition, since the soldering can be performed in an atmosphere in which the molten solder is slowly cooled, the molten solder has a substantially hemispherical shape which is a preferable bulging state due to its surface tension. Also, immediately before the start of solidification of the molten solder, it is rapidly cooled in an atmosphere at room temperature or lower, and it is possible to give the molten solder directional solidification in which the distance between its liquidus and solidus is substantially reduced. This allows the solder to have a finely solidified structure.

As a result, there is no solder balls, bridges, or solder splattering, and it is dense, has very few segregation of Pb and Sn, has excellent heat shock resistance, and has high quality, high quality non-oxidizing and non-cleaning. Soldering can be performed.

Further, according to the present invention, a preheating gas flow is injected around the tip tip, a low-temperature gas flow is injected as necessary around the tip, and the soldering portion is preheated with the preheating gas flow. Since the tip is used for soldering, there is little change in temperature of the tip due to contact with the soldering area, and the tip is heated by the preheating gas flow, resulting in almost all thermal stress on the tip Without this, the life of the tip can be greatly improved.

Claims

Scope of word blue

1. When using a soldering iron to blow the high-temperature gas flow to the soldering area of the work and solder the work,

A main heating gas flow at a temperature high enough to melt and soften the solder is ejected from the tip of the soldering iron, and a preheating gas flow at a temperature lower than the main heating gas flow and at a temperature sufficient to preheat the solder. Is blown around the main heating gas flow,

The main heating gas flow is blown to the soldering part of the preheated work while the preheating gas flow is blown to the soldering portion of the pre-heating to perform the soldering in the atmosphere surrounded by the preheating gas flow. A non-contact type soldering method characterized by being performed.

2. The non-contact type soldering method according to claim 1, wherein the soldering portion soldered by the main heating gas flow is gradually cooled by the preheating gas flow and then rapidly cooled to room temperature or lower.

3. The non-contact soldering method according to claim 1, wherein nitrogen gas or air is used for the main heating gas flow and / or the preheating gas flow.

4. When soldering the soldering area of the work with a soldering iron, apply a preheating gas flow from the tip of the soldering iron at a low temperature and at a temperature sufficient to preheat the solder. Spout around the chip,

After the preheated gas flow is sprayed onto the soldering portion of the peak to preheat, the soldered portion of the preheated peak is soldered by the above-mentioned tip in an atmosphere surrounded by the preheated gas flow. A contact type soldering method, characterized in that:

5. The contact-type soldering method according to claim 4, wherein the soldered portion soldered by the tip chip is gradually cooled by the preheating gas flow and then rapidly cooled to room temperature or lower.

6. A low-temperature gas flow, which is lower in temperature than the preheating gas flow, is injected around the preheating gas flow from the tip of the soldering iron. Protect the device from the heat of the preheated gas stream with a cold gas stream The contact-type soldering method according to claim 4 or 5, wherein

7. The contact-type soldering method according to claim 4, wherein nitrogen gas or air is used for the preheating gas flow and / or the low-temperature gas flow.

8. In a non-contact type soldering iron that performs soldering by blowing a high-temperature gas flow to the soldering part of the work,

The tip of the iron body is provided with a first nozzle at the center and a second nozzle which is open to cover the outside of the first nozzle,

A heating element is built in the iron body, and a main heating gas flow generation chamber is formed around or inside the heating element in communication with the first nozzle. A preheating gas flow generation chamber is formed around the chamber 1 in communication with the nozzle of the above 2;

The iron body has a gas supply passage for supplying gas to the main heating gas flow generation chamber and the preheating gas flow generation chamber.

Due to the heat generated by the heating element, a high-temperature main heating gas flow sufficient to melt and soften the solder is generated and ejected from the first nozzle, and convection from the main heating gas flow generation chamber or the heating element. Heating by heat and / or radiant heat produces a preheating gas flow at a lower temperature than the main heating gas flow and at a temperature sufficient to preheat the solder, and surrounds the main heating gas flow from a second nozzle. A non-contact soldering iron characterized by being blown out.

9. The trowel body is grounded, and a negative charge is electrostatically induced inside the main heating gas flow generation chamber 1 and the preheating gas flow generation chamber 1 to add a positive charge to the main heating gas flow and the preheating gas flow. 9. The non-contact soldering iron according to claim 8, wherein the soldering iron can be removed.

10. In a soldering iron whose tip can be heated by the heat generated by the heating element built in the iron body,

A preheating gas flow generation chamber is formed around the heating element with its distal end open to the periphery of the tip, and the temperature of the heating element is lower than that of the tip due to heat generated by the heating element. A contact-type soldering iron characterized in that a preheating gas flow force s' having a temperature sufficient to preheat the solder is generated and jetted around the tip.

1 1. A low-temperature gas flow generation chamber 1 is formed around the preheating gas flow generation chamber 1 with its front end side opened around the opening end of the preheating gas flow, and the preheating gas flow generation chamber is formed. 10.The contact type of claim 10, wherein a low-temperature gas flow lower in temperature than the preheating gas flow is generated by heating by convection heat and / or radiant heat from the air, and is jetted around the preheating gas flow. Soldering iron.

1 2. The iron body is grounded, and a negative charge is electrostatically induced inside the preheating gas flow generation chamber 1 and / or the low temperature gas flow generation chamber 1 to generate the preheating gas flow and Z or the low temperature gas flow. The contact-type soldering iron according to claim 10 or 11, wherein a positive charge can be removed.

1 3. It has a soldering iron shape as a whole, a heating element is built in the main body, and a heat retaining element is attached to the tip of the heating element, and the heat retaining element can be heated by the heat generated by the heating element. On the other hand, a high-temperature gas flow generation chamber is formed around the heating element with its distal end open around the distal end of the heat retaining element, and the high-temperature gas flow is generated by radiant heat from the heating element and the thermal retaining element. A high-temperature inert gas purging apparatus characterized in that a gas is generated and ejected forward.