JP3781697B2 - Method and apparatus for soldering electronic parts - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a soldering method and apparatus for surface mounting an electronic component on a printed circuit board.
[0002]
[Prior art]
As surface mount electronic components mounted on a printed circuit board or the like, there are flat package ICs (hereinafter referred to as FPICs) such as a QFP (Quad Flat Package) type and an SOP (Small Outline Package) type.
[0003]
The connection between the lead terminals of these electronic components and the wiring electrodes on the printed circuit board side is performed by a method such as soldering. Usually, as a soldering method, processing by a reflow furnace capable of mass production dominates. In the case of an electronic component that cannot be processed by a reflow furnace, a method using a soldering iron, a light beam, hot air, laser light, or the like is performed in a post-installation process.
[0004]
In addition, as a method for supplying the solder material to the soldering portion, a method in which a solder paste is screen printed in advance on a wiring pattern on a printed circuit board, a method using a dispenser capable of repeating a small amount of application, a solder wire, etc. There is an automatic supply method.
[0005]
Furthermore, flux is used together with the solder material at the time of soldering. The soldering mechanism is such that the flux first dissolves during heating, and the oxide film on the surface of the joint is chemically peeled off. Then, the melted solder spreads on the surface, and the lead terminals of the electronic component and the wiring electrodes of the printed circuit board are joined via the solder material.
[0006]
On the other hand, Japanese Patent Application Laid-Open No. 61-253170 discloses a laser generation source, and a laser irradiation unit for irradiating a bonded portion composed of solder and a workpiece with laser light generated from the generation source, There is disclosed a laser soldering apparatus characterized by further comprising a gas discharge means for removing a light shielding material generated from a bonded portion by irradiation of the laser light. Further, an embodiment is shown in which a gas is introduced into a laser light irradiation nozzle and a laser light emission port and a gas discharge port are shared. In addition, using heated air as a gas to remove the light shield is effective in improving soldering efficiency and solder quality, and using an inert gas results in soldering due to solder oxidation during soldering. It is described that it is effective in preventing deterioration of quality.
[0007]
Japanese Patent Application Laid-Open No. 5-104279 includes a light condensing unit having a light emitting part such as a xenon lamp or a YAG laser oscillator and a light condensing part of the light emitting part, and is located near the light condensing part. A light heating device that irradiates a heated object such as a soldering portion with condensed light to heat and melt the heated object, and the oxygen concentration in the atmosphere around the heated object is 5% or less An optical heating apparatus provided with a shield gas supply means made of an inert gas or a reducing gas is disclosed. Further, an embodiment in which the laser beam condensed by the condensing means is irradiated through the gas nozzle of the shielding gas is shown. Further, it is described that a soldering portion is preheated by using a gas temperature regulator and heating and using a shielding gas.
[0008]
In each of the above-mentioned JP-A-61-253170 and JP-A-5-104279, there is shown a method of performing soldering by using both laser beam irradiation and spraying of a heated inert gas or the like. Has been.
[0009]
Furthermore, in Japanese Patent Laid-Open No. 5-92275, an air blowing port is provided on one side of a main body case as a heating device for obtaining a uniform temperature distribution when preheating a board to be soldered. There is disclosed a heating device in which a heater is provided inside and a hot air blowing plate formed of a porous material for catalyst is provided in the opening on the other side of the main body case. Further, an embodiment using a material having a three-dimensional network skeleton structure based on urethane foam as a porous material for a catalyst is shown.
[0010]
[Problems to be solved by the invention]
In such a method of soldering electronic components, when the flux is melted and evaporated, and when the solder is melted, bubbles (gas) inside the melted solder expand and burst. It is easy to scatter. If the printed circuit board with the solder balls attached is used as it is, the solder balls may drop or move due to some vibration, etc., and enter other connection wiring parts, causing a short circuit and reducing the reliability of the printed circuit board. Become.
[0011]
Moreover, in the case of the process by the conventional reflow furnace, a solder ball, a flux residue, etc. have been removed by the following washing | cleaning process. However, recently, it has been pointed out that cleaning with chlorofluorocarbon or the like causes environmental problems, and the cleaning process is often omitted. For this reason, development of the soldering technique which can suppress generation | occurrence | production of a solder ball effectively was desired.
[0012]
Furthermore, in the soldering of post-installation parts that cannot be processed by a reflow furnace, for example, local heating is performed with a soldering iron, light beam, hot air, laser light, etc., but due to the sudden rise in temperature of the soldering part, etc. In some cases, more solder balls are generated.
[0013]
On the other hand, in particular, the above-mentioned Japanese Patent Application Laid-Open No. 5-104279 prevents the generation of solder balls by using laser beam irradiation together with spraying of a heated shield gas made of an inert gas or a reducing gas. Although it is shown that the heating gas is simply ejected from the tip of the nozzle, the temperature distribution in the heated range is high in the center, and the temperature gradually decreases as it spreads to the periphery Temperature distribution.
[0014]
As a result, for example, when soldering while moving a large number of lead terminals of the SOP, the temperature distribution at the joint location tends to be non-uniform, and solder balls are partially generated or wettability. There was a problem that there was a shortage.
[0015]
In addition, in the post-installation process of electronic components that cannot be continuously processed by the reflow furnace, the heating gas may be turned ON / OFF. In this case, when the heating gas is turned OFF, the ambient temperature rapidly decreases, and again, Since it takes time to recover the temperature when the heated gas is turned on, there is a problem that the processing time for soldering becomes long.
[0016]
Further, in the prior art disclosed in Japanese Patent Laid-Open No. 5-92275, although the substrate to be soldered can be preheated uniformly, the method of heating the entire substrate in advance in the processing by the reflow furnace, the joint portion is locally heated. Has a problem that it cannot be applied directly.
[0017]
The present invention has been made in view of the above problems, can suppress the generation of solder balls adhering to the periphery of a soldered portion of an electronic component, and can obtain a soldered portion with good wettability, and can be heated. An object of the present invention is to provide an electronic component soldering method and apparatus capable of soldering in a short time even when the gas is turned ON / OFF.
[0018]
[Means for Solving the Problems]
  In order to achieve the above object, the electronic component soldering method of the present invention is such that a lead terminal of an electronic component is placed on a wiring electrode of a printed circuit board, the laser beam is irradiated to the placement portion of the lead terminal, and inactive In a soldering method of an electronic component for performing soldering by blowing a heated shield gas made of a gas or a reducing gas, the optical axis of the laser beam is arranged in the blowout port of the shield gas,An inner nozzle having an opening through which the laser beam passes is disposed in the shielding gas blowing port, and a heater is disposed between the outer circumferential surface of the inner nozzle and the inner circumferential surface of the shielding gas blowing port for heating. Shield gas supply pathA heat storage material through which the shield gas can pass is provided at a position that does not substantially interfere with the traveling path of the laser light in the shield gas outlet.A part of the shield gas is introduced into the inner nozzle, and is caused to flow out of the blowout port through the opening, and the remainder of the shield gas is introduced into the heating shield gas supply path, and is flowed out through the blowout port of the shield gas. MakeIt is characterized by that.
[0019]
According to the soldering method of the present invention, the heated shield gas made of an inert gas or a reducing gas passes through the heat storage material in front of the blowout port, and is kept warm and stored. As a result, the blowing temperature and the gas pressure are made uniform, so that it is possible to uniformly heat the joint portion, thereby suppressing the generation of solder balls and improving the wettability of the solder.
[0020]
  In addition, even when heating gas is turned ON / OFF in the post-installation process of electronic components that cannot be processed continuously by the reflow furnace, the temperature of the ambient gas is reduced when the heating gas is turned off due to the heat retention / heat storage effect of the heat storage material. The soldering process can be performed quickly when the heated gas is turned on again..
[0021]
In the soldering method of the present invention, the heat storage material is preferably a metal porous mesh. According to this, since the metal is excellent in thermal conductivity and a large contact area is ensured by the porous mesh, more excellent heat retention and heat storage can be obtained.
[0022]
  Also,It is preferable that the shape of the shield gas blowout port is a long and narrow slit, and the laser light is condensed so as to be a linear beam while passing through the shield gas blowout port for irradiation. According to this, it is possible to preheat or preheat the shield gas at a time along a plurality of lead terminal rows protruding from the electronic component to form a non-oxidizing atmosphere, and in that state, along the lead terminal rows Since laser light can be irradiated at a time, a plurality of lead terminals can be simultaneously heated and soldered efficiently in a short time, and soldering workability can be further improved.
[0023]
  Further, the shield gas blowing port is rotated in accordance with the arrangement direction of the lead terminals of the electronic components installed on the wiring electrodes of the printed circuit board, and the linear beam of the laser beam is also rotated together with the blowing port. It is preferable to make it. According to this, even when the lead terminal protrudes from both the vertical side and the horizontal side of the chip of the electronic component, without changing the installation direction of the electronic component etc., the shield gas outlet and the laser beam The soldering operation can be performed simply by rotating the linear beam.
[0024]
  On the other hand, the electronic component soldering apparatus of the present invention is an electronic component soldering apparatus in which a lead terminal of an electronic component is installed on a wiring electrode of a printed circuit board and the installation portion of the lead terminal is heated and soldered. A laser beam irradiating means for condensing the laser beam and irradiating the laser beam at a predetermined location; and a shield gas spraying unit for spraying a heated shield gas made of an inert gas or a reducing gas to the predetermined location. A shaft is disposed in the shield gas outlet,An inner nozzle having an opening through which the laser beam passes is disposed in the shield gas outlet, and a heater is disposed between the outer peripheral surface of the inner nozzle and the inner peripheral surface of the shield gas outlet. A heating shield gas supply path is formed, a part of the shield gas is introduced into the inner nozzle, flows out from the outlet through the opening, and the remainder of the shield gas is introduced into the heating shield gas supply path. , Configured to flow out through the shield gas outlet,A heat storage material through which the shield gas can pass is provided at a position that does not substantially interfere with the traveling path of the laser light in the inert gas outlet.
[0025]
According to the soldering apparatus of the present invention, the heated shield gas made of an inert gas or a reducing gas passes through the heat storage material in front of the blowout port, and thus retains heat and stores heat. As a result, the blowing temperature and the gas pressure are made uniform, so that it is possible to uniformly heat the joint portion, thereby suppressing the generation of solder balls and improving the wettability of the solder.
[0026]
  In addition, even when heating gas is turned ON / OFF in the post-installation process of electronic components that cannot be processed continuously by the reflow furnace, the temperature of the ambient gas is reduced when the heating gas is turned off due to the heat retention / heat storage effect of the heat storage material. The soldering process can be performed quickly when the heated gas is turned on again..
[0027]
In the soldering apparatus of the present invention, the heat storage material is preferably a metal porous mesh. According to this, since the metal is excellent in thermal conductivity and a large contact area is ensured by the porous mesh, more excellent heat retention and heat storage can be obtained.
[0028]
  Also,The blowout port of the shield gas blowing means has an elongated slit shape, and the laser light irradiation means has light collecting means for condensing the laser light so as to be a linear beam, and is formed by this light collecting means. It is preferable that the optical axis of the linear beam is disposed in the outlet of the shield gas blowing means. According to this, it is possible to preheat or preheat the shield gas at a time along a plurality of lead terminal rows protruding from the electronic component to form a non-oxidizing atmosphere, and in that state, along the lead terminal rows Since laser light can be irradiated at a time, a plurality of lead terminals can be simultaneously heated and soldered efficiently in a short time, and soldering workability can be further improved.
[0029]
  Moreover, it is preferable to have a rotating means for rotating together the blowout port of the shield gas blowing unit and the linear beam having an optical axis in the blowout port. According to this, even when the lead terminal protrudes from both the vertical side and the horizontal side of the chip of the electronic component, without changing the installation direction of the electronic component etc., the shield gas outlet and the laser beam The soldering operation can be performed simply by rotating the linear beam.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
  1-3 show the present invention.ofOne embodiment of a soldering apparatus is shown.
[0031]
  FIG. 1 shows the present invention.byFIG. 2 is a schematic configuration diagram showing an embodiment of a soldering apparatus, and FIG.The present inventionFIG. 3 is a partially enlarged sectional view in the vicinity of a gas nozzle in the soldering apparatus according to FIG. 3, and FIG. 3 is a bottom view of FIG.
[0032]
  In FIG. 1, a laser oscillator 1 such as a YAG laser is connected to a condensing unit 3 via an optical fiber 2.In the present inventionThe laser beam irradiation means is constituted. The laser beam 4 output from the laser oscillator 1 is transmitted through the optical fiber 2 and condensed through the condensing unit 3.
[0033]
A gas nozzle 11 is attached to the laser light emitting surface of the light collecting unit 3. In this case, an air gap is provided at the connection boundary portion so that the heat of the heated shield gas is not heated due to conduction to the light collecting unit 3 side, and a heat insulating material such as “Duro Stone” (trade name, Roscheling Group) is installed to insulate the heat.
[0034]
As shown in FIG. 2, an inner nozzle 101 is provided on the inner diameter side of the gas nozzle 11, and the end surface of the gas nozzle 11 on the light collecting unit 3 side is covered with a transparent panel 19 that transmits laser light. A nozzle tip 16 having a shield gas outlet is attached to the opposite end face.
[0035]
Further, as shown in FIG. 3, a ring-shaped heat storage material 17 is disposed in the nozzle chip 16, and the laser light is centrally located so that the traveling path of the laser light does not substantially interfere with the heat storage material 17. A passage hole 18 is provided. As shown in FIG. 2, the end 101A of the inner nozzle 101 on the nozzle tip 16 side is formed in a conical shape that closes toward the nozzle tip 16, and the laser beam of the heat storage material 17 passes through the tip. An opening having the same inner diameter as that of the hole 18 is provided, and the heat storage material 17 is disposed so that the opening and the end surface of the heat storage material 17 on the light collecting unit 3 side are in contact with each other.
[0036]
An inlet 13 for introducing a shield gas 14 such as nitrogen gas is formed at one location on the peripheral surface of the gas nozzle 11. Further, in the space 111 between the gas nozzle 11 and the inner nozzle 101, an electric heater 12 and a thermocouple (not shown) for detecting and controlling the heating temperature are arranged. The introduced shield gas 14 is heated to form a high-temperature shield gas 15, and the high-temperature shield gas 15 is ejected through a heat storage material 17 disposed in the nozzle chip 16. The laser beam condensed through the condensing unit 3 is output through a laser beam passage hole 18 provided in the heat storage material 17.
[0037]
Further, the end 101B of the inner nozzle 101 on the light collecting unit 3 side is formed in a conical shape that opens toward the light collecting unit 3 side, and its tip is formed in contact with the inner peripheral surface of the gas nozzle 11. However, only the vicinity of the inlet 13 in the end 101B is provided with a notch 102 as shown in FIG. 2, and a part of the shield gas 14 flowing from the inlet 13 has the notch 102. Then, it flows into the space 112 on the inner diameter side of the inner nozzle 101 through the laser beam passage hole 18 and flows out as a shield gas 14A that is not heated. Note that the flow rate of the unheated shield gas 14A flowing out through the laser beam passage hole 18 may be very small, the space 112 through which the laser beam passes becomes slightly positive pressure, and the high temperature shield gas 15 ejected through the heat storage material 17 It suffices if it can be prevented from flowing back into the space 112.
[0038]
The shape of the inner nozzle 101 is not limited to the shape shown in FIG. 2, and a space 111 for housing the electric heater 12 and the thermocouple between the outer peripheral surface and the inner peripheral surface of the nozzle 11. Is formed, and a space 112 for the laser beam to pass through is formed on the inner diameter side thereof, and the shield gas 14 flowing from the introduction port 13 may be divided into the space 111 and the space 112.
[0039]
On the other hand, wiring electrodes 9 are formed on the surface of the printed circuit board 8, and for example, the lead terminals 6 of the electronic component 5 such as an FPIC (flat package IC) are installed so as to contact the corresponding portions of the wiring electrodes 9. Has been. A solder layer 7 formed by screen printing a solder paste is formed in advance on the soldered portion of the wiring electrode 9. And the part where the lead terminal 6, the solder layer 7, and the wiring electrode 9 contact | abutted up and down has comprised the joining location 10 which should be soldered.
[0040]
  next,the aboveUsing a soldering deviceOf the present inventionAn embodiment of a soldering method will be described.
[0041]
A plurality of lead terminals 6 extending from both sides of the electronic component 5 are positioned so as to come into contact with corresponding portions of the wiring electrodes 9 of the printed circuit board 8, and the electronic component 5 is placed on the printed circuit board 8. deep. The solder layer 7 is formed on the wiring electrode 9 to be soldered, and the lead terminal 6 is placed on the wiring electrode 9 through the solder layer 7. Moreover, as a solder material of the solder layer 7, a solder material for electronic parts such as a commonly used eutectic solder (Pb-Sn) or lead-free solder is used.
[0042]
In this state, a shield gas 14 such as nitrogen gas is introduced into the gas nozzle 11 from the introduction port 13. The shield gas 14 is heated to 50 to 300 ° C., more preferably 150 to 250 ° C., by the electric heater 12 disposed in the gas nozzle 11 to become a high temperature shield gas 15, and the high temperature shield gas 15 is converted into the heat storage material 17. And it is sprayed to the joint location 10 through the laser beam passage hole 18. At this time, the ejection pressure of the high-temperature inert gas 15 is preferably 0.01 to 0.5 MPa, and the flow rate is preferably 0.5 to 10 NL (liter) / minute (depending on the size of the workpiece).
[0043]
  here,In the present invention,Due to the presence of the heat storage material 17, the high temperature shield gas 15 is discharged at a uniform gas flow rate and temperature, so that a uniform pressure and temperature can be obtained at the joint 10. Thereby, since it becomes possible to pre-heat the joining location 10 uniformly, generation | occurrence | production of a solder ball is suppressed and the wettability of solder improves.
[0044]
As the heat storage material 17, a material having a heat storage property, in which the high-temperature shield gas 15 can pass through the heat storage material 17 and has a heat resistant temperature that can withstand high temperatures, can be used. It is preferable that the metal porous mesh is superior in thermal conductivity. As the metal, stainless steel is preferably used from the viewpoint of thermal conductivity, heat resistance, strength, cost, etc., but other special alloys such as Hastelloy and Monel can also be used.
[0045]
As such a heat storage material 17, for example, a stainless plate or the like in which precise holes of μm are uniformly distributed can be used. Such a metal porous mesh has a name of a porous metal plate, and, for example, those commercially available for the purpose of filtration, air flow, foaming, aeration, and silencing from, for example, Global Electronics Co., Ltd. can be suitably used. .
[0046]
Further, the shape of the outlet of the nozzle chip 16 is not necessarily circular as shown in FIG. The size of the blowout port of the nozzle chip 16 may be appropriately selected depending on the size and shape of the electronic component to be soldered. Usually, the inner diameter a in FIG. Is preferred.
[0047]
Further, the laser beam passage hole 18 is preferably as small as possible if the laser beam is opened so that the laser beam is not blocked by the heat storage material 17. For example, the inner diameter b is preferably 3 to 5 mm.
[0048]
As described above, after the joint 10 is uniformly preheated or preheated with the high temperature shield gas 15, laser irradiation from the laser oscillator 1 is performed.
[0049]
That is, the laser beam 4 output from the laser oscillator 1 is introduced into the condensing unit 3 through the optical fiber 2, is collected by a lens disposed in the condensing unit 3, passes through the gas nozzle 11, and passes through the nozzle. The light is emitted from the laser passage hole 18 of the heat storage material 17 at the outlet of the chip 16 and is locally irradiated to the joint portion 10, particularly the lead terminal 6.
[0050]
As a result, the solder layer 7 is melted and spreads around the portion irradiated with the laser beam 4, and the lead terminal 6 and the wiring electrode 9 are soldered. The oxide films on the surfaces of the lead terminals 6 and the wiring electrodes 9 are burned out and removed before soldering by spraying the high temperature shield gas 15, irradiating the laser beam 4, and flux. Further, since the portion irradiated with the laser beam 4 is a region where the high temperature shield gas 15 is sprayed, the heated portion is always shielded by the shield gas, and oxidation or the like is prevented.
[0051]
Furthermore, since the optical axis of the laser beam 4 is arranged in the blowout port of the nozzle tip 16 of the high temperature shield gas 15, the direction of the high temperature shield gas 15 can be visually confirmed by the laser beam 4, and the position adjustment can be performed. It's easy to do. In addition, since the spray direction of the high temperature shield gas 15 and the optical axis of the laser beam 4 are the same, the gas flow of the high temperature shield gas 15 can be sprayed from an angle that is not affected by the electronic component 5, for example, the vertical direction. .
[0052]
In the present invention, since the high temperature shield gas 15 is discharged at a uniform gas flow rate and temperature due to the presence of the heat storage material 17, it is possible to obtain a uniform pressure and temperature at the joint 10. . Thereby, since it becomes possible to pre-heat the joining location 10 uniformly, generation | occurrence | production of a solder ball is suppressed and the wettability of solder improves.
[0053]
Furthermore, even when the heating gas is turned on / off in the post-installation process of the electronic component, which cannot be continuously processed by the reflow furnace due to the heat storage effect of the heat storage material 17, the heating gas is maintained by the heat retention / heat storage effect of the heat storage material 17. Since the temperature of the atmospheric gas decreases little when the heating gas is turned off, and the temperature recovery when the heating gas is turned on again becomes faster, soldering can be performed in a short time.
[0054]
The output of the laser beam 4 is not particularly limited, but usually 1 to 40 W (depending on the type and size of the workpiece) is preferable.
[0055]
Laser oscillation using a YAG laser or the like is normally performed by continuous oscillation (CW), but the laser output can be pulsed. In this way, when the laser output is pulsed, the laser beam is melted when it is ON, and cooled when it is OFF. In addition, the setting of the pulse repetition frequency (Hz) or the pulse ON time makes it easy to control the melting temperature of the solder, so that a rapid temperature rise can be suppressed and the generation of solder balls can be suppressed. The quality of the attachment part can be improved.
[0056]
The internal shutter for pulsing the laser output includes a mechanical shutter that is turned on and off, and an electrical shutter that is turned on and off.
[0057]
The laser oscillator is not limited to a YAG laser, and other lasers can be used as long as thermal energy processing is possible. In addition, a normal CW • YAG laser may be used, but a commercially available normal pulse YAG laser can also be used when outputting a pulse. The normal pulse YAG laser has never been used for soldering because of its high peak output, but by suppressing the laser output (average output, power density, energy density) extremely low, Diversion is possible.
[0058]
Further, in the embodiment, the optical fiber is used as the laser beam transmission means, but the transmission means is not limited to this, and for example, means such as air transmission (for example, transmission of reflection by a mirror) can be used.
[0059]
Furthermore, the shielding gas may be either an inert gas or a reducing gas. Further, the inert gas used as the shielding gas is not limited to the nitrogen gas described above, but may be helium gas or argon gas which is a non-oxidizing gas. The reducing gas used as the shielding gas may be hydrogen gas, for example, or may be a mixed gas of an inert gas such as nitrogen gas as described above and a reducing gas such as hydrogen gas.
[0060]
Furthermore, the electronic component to be soldered to the printed circuit board is not limited to the FPIC, but can be applied to other ICs, chip resistors, electrolytic capacitors, and the like.
[0061]
In the present invention, the output (thermal energy) of the high temperature shield gas is made larger than the output (thermal energy) of the laser beam, the soldered part is mainly heated by the high temperature shield gas, and the heating by the laser beam irradiation is performed. Soldering may be performed by using auxiliary.
[0062]
That is, for example, in FIG. 1, when soldering the electronic component 5 such as FPIC onto the printed circuit board 8, the high temperature shield gas 15 is directly sprayed on the joint 10, and the temperature is 100 to 10 ° C. lower than the melting temperature of the solder. More preferably, it is heated to a temperature lower by 70 to 20 ° C., and in this state, laser light is supplementarily irradiated to melt the solder and soldering can be performed. When such soldering is performed, the region is heated uniformly by the high-temperature shield gas, and the central portion of the joint is irradiated with laser light to quickly reach a high temperature locally. This makes it possible to use heat energy efficiently without waste. Moreover, it can prevent that the joining location 10 is heated too much, can suppress generation | occurrence | production of a solder ball, and can also improve the wettability of a solder.
[0063]
  4 and 5,The present inventionAnother embodiment of the soldering apparatus is shown. Figure 4Of the present inventionFIG. 5 is a partially enlarged perspective view of the vicinity of a light collecting unit showing another embodiment of the soldering apparatus, and FIG. 5 is a bottom view of the nozzle chip in FIG. 4.
[0064]
This soldering apparatus uses a cylindrical lens 25 as a condensing means. The condensing unit 23 condenses the collimated laser beam 24 with a circular cross section by the cylindrical lens 25, and the laser beam 26 has a linear cross section. I have to.
[0065]
The nozzle chip 28 is configured by a rectangular parallelepiped having a rectangular cross-sectional shape, and a heat storage material 29 is disposed in the nozzle chip 28. Furthermore, as shown in FIG. 5, a slit-like laser beam passage hole 30 is provided in the center of the heat storage material 29 so that the traveling path of the linear laser beam 26 does not substantially interfere with the heat storage material 29. Thus, the high temperature shield gas 31 is blown out from the heat storage material 29 and the laser beam passage hole 30. The linear laser beam 26 is irradiated to the center in the gas spray region 32 of the high temperature shield gas 31 through the center of the laser beam passage hole 30. The condensing means is not limited to the cylindrical lens, and any condensing means may be used as long as it condenses so that the cross section of the laser light is linear.
[0066]
The size of the outlet of the nozzle chip 28 may be appropriately selected depending on the size and shape of the electronic component to be soldered. Usually, the width c (mm) and the length d (mm) of the inner diameter in FIG. ) Is preferably c ≧ C + 2 and d ≧ D + 2 if the size of one side of the FPIC is a width C (mm) and a length D (mm), for example. For example, when the size of one side of a lead of an SOP (Small Outline Package), which is an FPIC to be soldered, is 3 mm wide × 18 mm long, the size of the outlet is 5 mm (mm). ) × length 20 (mm), it is possible to correspond to the width and length of one side of the SOP.
[0067]
Thus, when soldering using this soldering apparatus, the high temperature shield gas 31 blown out from the nozzle tip 28 forms an elongated gas blowing region 32 and gas shields one side of the lead terminal of the SOP. be able to. By sequentially irradiating the lead terminals while moving the linear laser beam 26 in this state, for example, one side of a large number of lead terminals of the FPIC can be soldered at a time. In addition, since the laser beam 26 is irradiated into the gas blowing region 32 of the high temperature shield gas 30, high-quality, high-quality soldering is performed in a non-oxidizing atmosphere and in a preheated or preheated state. Is possible.
[0068]
In addition, since the gas spraying region 32 also moves as the linear laser beam 26 is moved, the gas spraying region 32 does not always shield all of the lead terminals on one side, but in practice this is the case. It is enough. Note that the length of the gas outlet may be made longer so that complete gas shielding can always be performed against the movement of the linear laser beam 26.
[0069]
  FIG. 6 shows a soldering apparatus according to the present invention.Yet anotherAn embodiment is shown. As shown in the figure, this soldering apparatus is composed of a cylindrical lens 25, a gas nozzle 27, and a nozzle chip 28 in the configuration of the soldering apparatus shown in FIG. The lens / gas nozzle unit 33 is configured to be rotatable about the laser optical axis 34 by a driving mechanism (not shown).
[0070]
That is, the cylindrical lens 25 can rotate in any direction around the optical axis 34, and at that time, the gas nozzle 27 and the nozzle tip 28 also rotate together in the same direction. In addition, the circular laser beam 24 is condensed by the cylindrical lens 25 to become a linear laser beam 26 and finally irradiated as a linear beam 35. The linear beam 35 is also emitted from the cylindrical lens 25. By rotation, it rotates in the same direction.
[0071]
Therefore, even when a lead wire comes out from each side of an electronic component, for example, FPIC, by rotating the lens gas nozzle unit 33 in accordance with the direction of each side, an elongated rectangular gas outlet and linear shape The beam 35 can be made to coincide with the arrangement direction of the lead wires on each side.
[0072]
As a result, after soldering along the arrangement direction of a plurality of lead wires protruding from one side of the FPIC, along the arrangement direction of a plurality of lead wires protruding from the other side perpendicular thereto The lens gas nozzle unit 33 can be rotated and soldered. By repeating this operation, all the lead wires can be efficiently soldered without changing the arrangement of the FPIC.
[0073]
【Example】
  Using the soldering apparatus shown in FIG. 1, the lead terminals 6 of the electronic component 5 made of FPIC placed on the wiring electrodes 9 of the printed circuit board 8 are passed through the solder layer 7 formed in advance on the wiring electrodes 9. And soldered. In this embodiment, the solder material of the solder layer 7 is Sn—Ag—Cu based lead-free solder among the solder materials for electronic components. The melting temperature of this solder material is about 220 to 221 ° C.
[0074]
Nitrogen gas was used as the shielding gas 14, and this nitrogen gas was heated to 250 ° C. by the electric heater 12 and sprayed from the outlet of the nozzle chip 16 under conditions of a pressure of 0.2 MPa and a flow rate of 1.5 NL / min.
[0075]
Further, in the nozzle chip 16, as a heat storage material 17, a stainless steel material with a porosity of 30%, a thickness of 5 mm, a diameter of 10 mm and a ring-shaped metal porous hole provided with a 3 mmφ laser light passage hole 18 in the center. A quality mesh was placed.
[0076]
On the other hand, as the laser oscillator 1, a YAG laser was used, and laser light with an output of 10 W was irradiated for 0.3 seconds (per lead terminal).
[0077]
At the time of soldering, first, the shielding gas 14 is blown to heat the portion to be soldered to a temperature 30 ° C. lower than the melting temperature of the solder layer 7, and the portion to be soldered with the laser light in that state The solder was melted by spot-irradiating the center of the solder to perform soldering.
[0078]
As a result, the soldering speed could be 0.3 seconds per lead terminal, and there were no solder balls on the soldered printed circuit board 8.
[0079]
In addition, since the spraying direction of the shield gas 14 and the optical axis of the laser beam 4 coincide, it is easy to position the heating spot.
[0080]
【The invention's effect】
  As described above, according to the present invention, when soldering an electronic component, a laser beam and a high-temperature shield gas are used in combination, and the optical axis of the laser beam is disposed in the gas nozzle outlet of the high-temperature shield gas.As well asBy providing a heat storage material through which the shield gas can pass in a position that does not substantially interfere with the laser beam traveling path in the shield gas blowout port, the soldering portion that suppresses the generation of solder balls and has good wettability Can get theMoreover,Even when the heating gas is turned ON / OFF, soldering can be performed in a short time.
[Brief description of the drawings]
[Figure 1]The present inventionIt is a schematic block diagram which shows one Embodiment of the soldering apparatus by.
FIG. 2 is a partially enlarged sectional view in the vicinity of a gas nozzle in the soldering apparatus.
FIG. 3 is a bottom view of FIG. 2;
[Fig. 4]The present inventionIt is a partial expansion perspective view of the condensing unit vicinity which shows other embodiment of the soldering apparatus by A.
FIG. 5 is a bottom view of the nozzle tip in FIG. 4;
FIG. 6 shows a soldering apparatus according to the present invention.Yet anotherIt is a partial expansion perspective view of the condensing unit vicinity which shows embodiment.

Claims (8)

A lead terminal of an electronic component is installed on the wiring electrode of the printed circuit board, and a laser beam is irradiated to the installation portion of the lead terminal, and a heated shield gas made of an inert gas or a reducing gas is sprayed and soldered. In the method of soldering electronic components to be performed,
The optical axis of the laser beam is arranged in the shield gas outlet,
An inner nozzle having an opening through which the laser beam passes is disposed in the shield gas outlet,
Between the outer peripheral surface of the inner nozzle and the inner peripheral surface of the shield gas outlet, a heater is disposed to form a heating shield gas supply path,
A heat storage material through which the shield gas can pass is provided at a position that does not substantially interfere with the traveling path of the laser light in the outlet of the shield gas ,
Introducing a portion of the shielding gas into the inner nozzle, allowing it to flow out of the outlet through the opening,
A method of soldering an electronic component, wherein the remaining part of the shield gas is introduced into the heating shield gas supply path and flows out through the outlet of the shield gas .   The method of soldering an electronic component according to claim 1, wherein the heat storage material is a metal porous mesh. 3. The shield gas blow-out port is formed in an elongated slit shape, and the laser light is condensed so as to be a linear beam and irradiated through the shield gas blow-out port. Soldering method for electronic parts. The shield gas blowout port is rotated in accordance with the arrangement direction of the lead terminals of the electronic components installed on the wiring electrodes of the printed circuit board, and the linear beam of the laser beam is also rotated together with the blowout port. Item 4. A method for soldering an electronic component according to Item 3. In an electronic component soldering apparatus for installing a lead terminal of an electronic component on a wiring electrode of a printed circuit board and heating and soldering the installation portion of the lead terminal,
A laser beam irradiation means for condensing the laser beam and irradiating a predetermined location;
A shield gas spraying means for spraying a heated shield gas made of an inert gas or a reducing gas to a predetermined location;
The optical axis of the laser beam is disposed in the shield gas outlet,
An inner nozzle having an opening through which the laser beam passes is disposed in the shield gas outlet, and a heater is disposed between the outer peripheral surface of the inner nozzle and the inner peripheral surface of the shield gas outlet. A heating shield gas supply path is formed, a part of the shield gas is introduced into the inner nozzle, flows out from the outlet through the opening, and the remainder of the shield gas is introduced into the heating shield gas supply path. , Configured to flow out through the shield gas outlet,
An electronic component soldering apparatus, wherein a heat storage material through which the shield gas can pass is provided at a position that does not substantially interfere with the traveling path of the laser beam in the blowout port of the inert gas.   The electronic component soldering apparatus according to claim 5, wherein the heat storage material is a metal porous mesh. The outlet of the shield gas blowing means has an elongated slit shape, and the laser light irradiation means has a light collecting means for condensing the laser light so as to be a linear beam, and is formed by this light collecting means. The electronic component soldering apparatus according to claim 5 or 6, wherein an optical axis of the linear beam is disposed in an outlet of the shield gas blowing means. The electronic component soldering apparatus according to claim 7, further comprising a rotating unit that rotates together the blowout port of the shield gas spraying unit and the linear beam having an optical axis in the blowout port.

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