JP2011216503A - Soldering method, method for manufacturing mounting substrate and soldering apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a soldering method capable of properly melting solder for connecting an electronic component to a substrate.SOLUTION: Solder balls 101 of a BGA 100 and lands 103 imparted with solder on the substrate 107 are irradiated with a laser beam via a mirror unit 351 between them in a state that the solder balls 101 and the lands 103 are separated. The solder is melted by laser irradiation, then, the mirror unit 351 is pulled out and the BGA 100 is lowered to a position of the substrate 107 by a suction nozzle 353 to solder the BGA 100 to the substrate 107.

Description

  The present invention relates to a soldering method, a mounting board production method, and a soldering apparatus, and more particularly to a soldering method for melting solder for connecting an electronic component and a board, a mounting board production method, and a soldering apparatus. .

  Some electronic components mounted on a printed circuit board have a solder joint at the bottom of the component (back-bonded electronic component). These are BGA (Ball Grid Array), CSP (Chip Size Package), LGA (Land Grid Array), WL-CSP (Wafer Level Chip Size Package), POP (Package on PackageL), LC. Carrier) and the like.

  Conventionally, such back junction electronic components are soldered in the following steps in the same manner as other surface mount components.

  ・ Printing process of solder paste on printed circuit board (or dispensing process)

  ・ Component mounting process on printed circuit board

  ・ Soldering process by reflow furnace

  As described above, the soldering of the electronic components to the printed circuit board is often performed at once in a reflow furnace. In addition, due to environmental concerns, it is now necessary to adopt lead-free solder that does not contain lead as a substitute for lead-containing solder. Since the melting temperature of lead-free solder is higher than the melting temperature of lead-containing solder, the temperature of the reflow furnace must be raised to about 240 ° C. The heat-resistant temperature of many electronic components is 250 ° C., and the temperature setting margin of the reflow furnace is as narrow as about 10 ° C.

  On the other hand, since there is a temperature distribution in the furnace, it is difficult to set the temperature inside the furnace as ideal. For this reason, the number of parts that cannot withstand the temperature and become defective products is increasing.

  For these reasons, recently, there is an increasing expectation for local heating soldering using a laser in which only a joint is heated and soldered without applying a thermal load to an electronic component.

  As a method of joining mounted components by light energy irradiation, there is a technique disclosed in Patent Document 1 below.

Patent Document 1 is an electronic component connection method in which an electronic component having weak heat resistance and an electronic component having heat resistance are electrically connected to a substrate, and only the heat resistant component is mounted on the substrate and heated in a reflow furnace. Thus, a technique for soldering heat-resistant parts on a substrate at once is disclosed. Thereafter, the weak heat-resistant component is mounted on the connection portion of the weak heat-resistant component, and the solder is remelted by performing local heating, and the weak heat-resistant component is soldered.
Japanese Examined Patent Publication No. 7-70824

  However, the technique of Patent Document 1 has a problem in that it is difficult to join a back-joint component or the like in which the joint is almost hidden from the substrate.

  The present invention has been made to solve such problems, and a soldering method capable of appropriately dissolving solder for connecting an electronic component and a substrate, a method for producing a mounting substrate, and solder The object is to provide an attaching device.

  In order to achieve the above object, according to one aspect of the present invention, in a soldering method for connecting an electronic component and a substrate, at least one of a connection location of the electronic component to the substrate and a connection location of the substrate to the electronic component A solder is applied to the surface. In the soldering method, the electronic component and the substrate are separated from each other, the light irradiation process for irradiating light to the connection part of the electronic component to the substrate and the connection part of the substrate to the electronic component, and soldering by the light irradiation process. And the step of soldering the connection portion of the electronic component to the substrate and the connection portion of the substrate to the electronic component with solder by shortening the distance between the electronic component and the substrate.

  According to this invention, in a state where the electronic component and the substrate are separated from each other, light irradiation is performed on the connection portion of the electronic component to the substrate and the connection portion of the substrate to the electronic component. After the solder is melted by light irradiation, the distance between the electronic component and the substrate is shortened, whereby the connection location of the electronic component to the substrate and the connection location of the substrate to the electronic component are soldered. By irradiating light to the connection part of the electronic component to the substrate and the connection part of the substrate to the electronic component, the solder temperature can be set to a desired temperature. Further, by performing light irradiation in a state where the electronic component and the substrate are separated from each other, light can be easily applied to the connection portion of the electronic component to the substrate and the connection portion of the substrate to the electronic component. In the present invention, the term “solder” is mainly used for solders mainly composed of lead and tin (so-called lead-containing solder), silver-containing solder, gold-based solder, tin / silver / copper, tin / bismuth, and the like. Used comprehensively including the concept of lead-free solder as a component. In addition, the term “solder” is used to include the concept of solder that includes additives such as flux to prevent oxidation and facilitate bonding. Furthermore, the term “solder” is used to include the concept of solder paste or solder cream.

  Preferably, the electronic component is a back surface bonded component in which the connection portion to the substrate is substantially hidden when mounted on the substrate.

  The present invention can be satisfactorily applied to such a back-surface bonded component in which the connection portion to the substrate is substantially hidden when mounted on the substrate. That is, since the light irradiation can be performed in a state where the electronic component and the substrate are separated from each other, light can be favorably applied to a connection portion to the substrate that is substantially hidden when mounted on the substrate.

  Preferably, flux is applied to both the connection part of the electronic component to the substrate and the connection part of the substrate to the electronic component.

  Thus, soldering can be performed more favorably by performing soldering using flux and solder.

  Preferably, in the soldering step, the electronic component is positioned above the bonding position of the substrate by the conveying member, the distance between the electronic component and the substrate is set to a predetermined distance, and then the electronic component is separated from the conveying member. Move the conveying member away from the electronic component.

  In this way, after the distance between the electronic component and the substrate is set to a predetermined distance, the electronic component is separated from the conveying member, and then the conveying member is moved away from the electronic component, so that self-alignment of the electronic component is not hindered. Therefore, the electronic component can be positioned satisfactorily.

  Preferably, in the soldering method, the connection position of the electronic component to the substrate and the connection position of the substrate to the electronic component are aligned by a camera coaxial with the light irradiated in the light irradiation step.

  In this way, the position where the electronic component is connected to the substrate and the position where the electronic component is connected to the electronic component are aligned by the camera coaxial with the light irradiated in the light irradiation step, thereby confirming the light irradiation position. And positioning of the connection points can be performed satisfactorily.

  Preferably, when the light irradiation is performed in the light irradiation step, the electronic component is held horizontally vertically above the bonding position of the substrates.

  In this way, when performing light irradiation in the light irradiation step, the electronic component is held horizontally vertically above the bonding position of the substrate, so that the subsequent electronic component and substrate can be brought close to each other and soldered smoothly. It becomes possible to carry out. Moreover, since it is not necessary to move the electronic component sideways after the solder is melted, the solder is prevented from flowing or dropping.

  Preferably, the light source for light irradiation is a semiconductor laser, a xenon lamp, or an infrared lamp.

  By using such a light source, the solder can be dissolved well.

  Preferably, there are a plurality of locations where the electronic component is connected to the substrate and a location where the substrate is connected to the electronic component, and the solder is provided at a plurality of locations as solder bumps. The light irradiation process is performed by a galvanometer mirror. Irradiate a plurality of connection points of the component and a plurality of connection points of the substrate.

  Thus, by irradiating a plurality of connection parts of the electronic component and a plurality of connection parts of the substrate with the galvanometer mirror, it becomes possible to efficiently dissolve the solder.

  Preferably, in the light irradiation step, irradiation is performed with one or two beams.

  Thus, by performing light irradiation with a single beam or a plurality of beams, it becomes possible to efficiently and accurately melt the solder.

  Preferably, the soldering method further includes a step of measuring a temperature at a position where the light is irradiated in the light irradiation step, and the soldering step has a temperature measured by the step of measuring the temperature being a melting temperature of the solder. After detecting this, soldering is performed.

  By measuring the temperature at the position where light is irradiated in this way, soldering can be performed while keeping the temperature of the solder appropriately.

  Preferably, the soldering method heats at least one of the electronic component and the substrate before soldering.

  As described above, by heating at least one of the electronic component and the substrate before soldering, it is possible to prevent the soldering temperature from being lowered before soldering to cause defective soldering.

  When the other aspect of this invention is followed, the production method of a mounting board will produce the board | substrate with which the electronic component was mounted by the soldering method in any one of said.

  According to this, by performing light irradiation in a state where the electronic component and the substrate are separated from each other, it is possible to easily apply light to the connection portion of the electronic component to the substrate and the connection portion of the substrate to the electronic component. There is an effect that the production of the substrate can be suitably performed.

  According to still another aspect of the present invention, in a soldering apparatus for connecting an electronic component and a substrate, at least one of a connection portion of the electronic component to the substrate and a connection portion of the substrate to the electronic component is soldered. Is granted. The soldering apparatus is a state in which the electronic component and the substrate are separated from each other, the light irradiation mechanism for irradiating light to the connection portion of the electronic component to the substrate and the connection portion of the substrate to the electronic component, and solder by light irradiation. After melting, the distance between the electronic component and the substrate is shortened to provide a mechanism for soldering the connection portion of the electronic component to the substrate and the connection portion of the substrate to the electronic component with solder.

  According to this invention, by performing light irradiation in a state where the electronic component and the substrate are separated from each other, it is possible to easily apply light to the connection portion of the electronic component to the substrate and the connection portion of the substrate to the electronic component. There exists an effect that the apparatus which performs soldering suitably can be provided.

  [First Embodiment]

  FIG. 1 is a plan view showing the configuration of the soldering apparatus according to the first embodiment of the present invention.

  Referring to the figure, the soldering apparatus includes a board transport apparatus 251 that transports the board 107 on which electronic components are placed on the base to a position indicated by a position 107 ', and an XY above the base. And a laser head 200 movable along a plane. In the following, a method for soldering BGA to a substrate will be described.

  The soldering apparatus includes a driving device 271 that moves the laser head 200 in the X direction, the Y direction, and the R (rotation) direction. Further, the soldering apparatus includes a tray 273 for stocking BGA to be mounted on the board 107, a position correcting camera unit 275 for photographing the inclination and position of the BGA sucked by the component sucking nozzle, and a connection position of the BGA to the board. And a flux application unit 277 for applying a flux.

  The laser head 200 includes a laser light source that emits a laser beam, a galvano mirror that reflects the emitted laser beam, and a mirror that guides the laser beam to the bonding surface of the BGA to the substrate and the bonding surface of the substrate to the BGA.

  A solder paste (including flux) is applied to the connection portion of the substrate with the BGA. Flux is applied to the solder balls which are the connection locations of the BGA. Before mounting the BGA on the substrate, both the connection portion on the substrate side and the connection portion on the component side are heated to the solder melting temperature or higher by light irradiation. By shortening the distance between the substrate and the BGA while the solder is above the melting temperature, both can be soldered together.

  FIG. 2 is a side view showing the configuration of the laser head 200 of FIG.

  In the soldering apparatus, the substrate 107 is placed on a stage (base) (not shown) and conveyed from left to right in the drawing.

  As shown in the figure, the laser head 200 includes a semiconductor laser light source 303 that supplies a laser to a laser irradiation device 307 via a flexible optical cable (optical fiber) 305, and a laser beam from the laser irradiation device 307 as a half mirror. (Beam splitter) Galvano mirrors 311 and 313 for allowing the laser beam to be reflected after being transmitted through 309, a telecentric lens 315 for irradiating the laser beam from the galvano mirror directly below, and telecentric Lens drive systems 317a and 317b for focusing the lens, an image pickup apparatus 301 that moves to the upper side of the electronic component before the electronic component is soldered, and picks up an image of the lower side, a half mirror 309, and a lens 321 , Laser irradiation position coaxial with laser beam A coaxial camera 323 that captures the image from the image, an image processing unit 325 that processes a captured image of the coaxial camera 323, and a control that controls on / off of the stage position and angle, the angle of the galvanometer mirror, and the laser output based on the captured image. Unit (controller) 327.

  In addition, the laser head 200 sucks the BGA 100 to suck the component suction nozzle 353 that transports the BGA 100 from the tray 273 to the component mounting position, and the laser beam that vertically descends from the telecentric lens 315 to the component suction nozzle 353. The mirror unit 351 for irradiating the bonded surface of the BGA 100 to the substrate 107, the bonded portion of the substrate 107 to the BGA 100, the exhaust device 357 for exhausting the melted solder paste and flux mist, and the substrate of the BGA 100 A height sensor 361 (such as a laser distance measuring sensor) that measures a position in the height direction from 107.

  The mirror unit 351 includes upper mirrors 351 a and 351 b for irradiating a laser beam vertically descending from the telecentric lens 315 to the bonding surface of the BGA 100 adsorbed by the component adsorption nozzle 353 to the substrate 107, and the telecentric lens 315. Lower mirrors 351c and 351d are provided for irradiating the laser beam that has descended vertically onto the joint portion of the substrate 107 to the BGA 100. The mirror unit 351 can move in the horizontal direction of the drawing, and the mirrors 351a to 351d move with the movement of the mirror unit 351.

  Further, the laser head 200 includes a radiation thermometer 355b that measures the temperature of the joint portion of the BGA 100 to the substrate 107, and a radiation thermometer 355a that measures the temperature of the joint portion of the substrate 107 to the BGA 100. Soldering is performed after detecting that the temperature measured by these thermometers has reached the melting temperature of the solder.

  By the action of the galvanometer mirror, the laser beam from the laser irradiation device 307 is sent in the direction indicated by the solid line arrow, whereby the laser beam can be guided to the plurality of solder balls 101 of the BGA 100. Further, by the action of the galvanometer mirror, the laser beam from the laser irradiation device 307 is sent in the direction indicated by the dotted arrow, thereby guiding the laser beam to a plurality of lands 103 (with solder paste applied) of the substrate 107. Can do.

  The imaging device 301 images a predetermined mark on the substrate 107 and detects the mounting position and direction of the BGA 100.

  The irradiation position of the laser is observed with the coaxial camera 323. Based on this, the control unit 327 adjusts the laser irradiation position so that the laser is irradiated to an appropriate position.

  In order to align the position of the solder ball 101 of the BGA 100 with the position of the land 103 of the substrate 107, the fiducial mark (recognition mark) of the substrate 107 is read by the image pickup device 301, and the solder ball 101 of the BGA 100 is read. A method of reading the position with the camera unit 275 and aligning both can be employed. Alternatively, before or while heating the BGA 100 on the land 103 of the substrate 107 or during heating, the position of the solder ball 101 of the BGA 100 and the position of the land 103 of the substrate 107 by the coaxial camera 323 coaxial with the heating light source. And a method of aligning the two can be employed. Moreover, it is good also as employ | adopting these two methods together.

  Further, when both the solder balls 101 of the BGA 100 and the lands 103 of the substrate 107 are heated to the solder melting temperature or higher by light irradiation, the holding position of the BGA 100 is substantially vertically above the place where the lands 103 of the substrate 107 are located. It is desirable to hold substantially horizontally.

  FIG. 3 is a view of the BGA 100 as viewed from the side where the plurality of solder balls 101 are provided.

  The laser beam irradiation spot 101a moves in the direction indicated by the arrow by the action of the galvanometer mirror. As a result, the laser beam is scanned. By scanning, all the solder balls 101 are sequentially irradiated with a laser beam. Thereby, all the solder balls 101 can be dissolved.

  Similarly, all lands 103 of the substrate 107 located at positions corresponding to the solder balls are also irradiated with a laser beam. Thereby, all the solder paste on the land 103 can also be dissolved.

  Further, in order to make the temperature of the laser irradiation portion uniform, it is desirable that the laser light is irradiated to the BGA solder ball and the land portion of the substrate in a plurality of times at high speed.

  FIG. 4 is a diagram showing a process of performing soldering from a state in which the solder is dissolved by the process of FIG.

  Before mounting the BGA, the distance between the BGA and the substrate is measured by the height sensor 361. The stop position of the component suction nozzle 353 is determined by calculating the clearance (solder ball height + solder paste application thickness) necessary for solder joining.

  When the BGA is mounted, the mirror unit 351 is moved in the “A” direction in FIG. 4 to make a space between the BGA 100 and the substrate 107. The suction nozzle 353 moves the BGA 100 to the determined stop position (lowered in the “B” direction in FIG. 4). Thereafter, the BGA 100 is separated from the suction nozzle 353. Subsequent to the suction nozzle 353 separating the BGA 100, the suction nozzle 353 is moved away from the BGA 100 so as not to interfere with the self-alignment of the BGA 100. The BGA 100 is electrically connected to the substrate 107 as the solder temperature decreases.

  5-7 is a flowchart which shows the operation | movement which a soldering apparatus performs.

  In step S101, a substrate on which a solder paste is applied and a component other than the back joint component such as BGA is mounted is supplied to a soldering place. In step S103, the imaging device 301 reads a fiducial mark (recognition mark) on the substrate 107. In step S105, the board position and the connection position of the back joint component such as BGA are recognized.

  In step S107, the BGA 100 is picked up from the tray 273 by the component suction nozzle 353. In step S109, the position of the solder bump 101 of the BGA 100 picked up by the camera unit 275 is recognized.

  In step S <b> 111, the flux is transferred to the BGA 100 by the flux application unit 277. In step S113, the BGA 100 is carried over the mounting position on the substrate 107, and the deviation is corrected.

  In step S115 (FIG. 6), the mirror unit 351 is inserted between the BGA 100 and the substrate 107.

  In step S117, the solder balls 101 of the BGA 100 and the lands 103 of the substrate are heated with a laser so that the solder melting temperature is equal to or higher than the solder melting temperature (state shown in FIGS. 2 and 3).

  In step S119, when it is confirmed by the radiation thermometers 355a and 355b that the solder ball 101 of the BGA 100 and the land 103 of the substrate are equal to or higher than the target temperature, the laser is stopped in step S121.

  In step S123, the mirror unit 351 between the BGA 100 and the substrate 107 is pulled out. Thereafter, in step S125, the BGA 100 is moved to a mounting position on the substrate 107 (state shown in FIG. 4).

  In step S127, the suction of the suction nozzle 353 is stopped, and the BGA 100 is separated from the suction nozzle 353. Thereby, in step S129, the BGA 100 is soldered to the bonding position of the substrate by self-alignment. When soldering a plurality of BGAs, the processes of steps S107 to S129 are repeated.

  In step S131 and thereafter, soldering is performed by laser irradiation of components other than the back-joined components using the laser head 200. In step S131, the laser head 200 is moved to the parts position in the programmed order. In step S133, the target component is irradiated with a laser to solder the component to the substrate. If there is a next part, the laser head 200 is moved to the position of the next sequential part programmed in step S135, and laser irradiation from step S133 is repeated.

  In step S137, when the laser irradiation to all target components on the substrate is completed, the laser head 200 is moved to the original position in step S139. In step S141, the substrate that has completed laser irradiation is discharged.

  In this manner, the BGA can be mounted after the BGA bonding surface and the substrate bonding surface are heated with light before the BGA is mounted and the solder is melted.

  Such solder joining by light energy may be performed as a post-process of soldering in a reflow furnace. That is, after soldering a component that is resistant to temperature in a reflow furnace, local heating soldering that heats the joint with light energy may be performed on an electronic component that does not require a thermal load. Of course, the reflow furnace process may be omitted and all components may be soldered by laser.

  Further, as shown in the flowcharts of FIGS. 5 to 7, for the back-joined electronic component having a solder joint at the bottom of the component, soldering using the mirror unit 351 is performed and placed on the substrate. For electronic components other than back-bonded electronic components that can be soldered by irradiating light, soldering is performed by irradiating light from above with the components mounted on the substrate without using the mirror unit 351. It is good also as performing.

  [Effects of the embodiment]

  According to the embodiment described above, the mounting surface side of the back surface bonding component (BGA, LGA, CSP, WL-CSP, POP, LCC, etc.) and the land portion of the board before mounting are almost completely hidden during mounting. After heating with light energy, soldering can be performed.

  Moreover, soldering can be performed satisfactorily by heating both the mounting surface side of the back junction component and the land portion of the substrate.

  Furthermore, since only the joining portion can be heated, the thermal load on the components can be suppressed. That is, since local heating is performed, there is a low possibility that the temperature is higher than the temperature at which the back-joined parts are damaged (for example, 250 ° C.).

  Furthermore, the self-alignment in the positioning of the components can be performed by releasing the back surface joining component after the back surface joining component is brought close to the substrate by a predetermined distance in a state where the solder is melted.

  Further, in the conventional method using a reflow furnace, there is a problem that stress may concentrate on the four corners of the back-joined part due to thermal expansion of the part and the substrate. In this embodiment mode, since local heating can be performed, such a problem can be solved.

  Furthermore, in the conventional method using a reflow furnace, since the solder is gradually cooled, a thick copper-tin alloy layer can be formed at the interface between the copper electrode and the solder. Since this layer is hard and brittle, there is a problem in that parts fall off due to impact such as dropping. In this embodiment, the solder is rapidly cooled to perform local heating. For this reason, the said alloy layer becomes thin and there exists an effect that impact strength, such as dropping, increases.

  In addition, by holding the BGA horizontally vertically above the bonding position of the board, it is not necessary to move the BGA sideways after melting the solder, preventing the solder from flowing or dropping sideways. Is done.

  Furthermore, in the conventional method using a reflow furnace, there is a problem that voids are generated in the solder balls, and the joint strength of the components may be reduced.

  FIG. 8 is a cross-sectional view showing a problem of the conventional method using a reflow furnace.

  When the electrode 105 of the BGA 100 and the land 103 of the substrate 107 are connected by soldering using a reflow furnace, the BGA 100 becomes a lid and blocks the path through which the gas generated during heating from the solder paste escapes. . Thereby, the void V may generate | occur | produce in the upper part in the solder 101b after soldering.

  FIG. 9 is a diagram for explaining the effect (prevention of void generation) in the present embodiment.

  As shown in FIG. 9A, with the BGA 100 and the substrate 107 separated (before covering (mounting) with the BGA), the solder ball 101 and the solder on the land 103 are irradiated with laser. Thus, it is possible to perform degassing which is a cause of generation of voids.

  As a result, as shown in FIG. 9B, voids are prevented from occurring in the solder 101b after soldering. Thereby, it is possible to provide a solder joint that is void-free and resistant to impact.

  [Second Embodiment]

  FIG. 10 is a side view showing the configuration of the laser head in the second embodiment.

  This laser head can be used in place of the laser head of FIG. In the soldering apparatus, the substrate 107 is placed on a base (stage) 359 and conveyed from left to right in the drawing.

  As shown in the figure, the laser head reflects a laser beam by a semiconductor laser light source 463 that supplies a laser to a laser irradiation device 467 via a flexible optical cable (optical fiber) 465 and a half mirror (beam splitter) 469. A laser irradiation device 467 that outputs the laser beam, a laser beam shaping lens 453 that shapes a laser beam from the laser irradiation device 467, and an imaging device that moves to above the electronic component before the electronic component is soldered and images the lower portion 471, via a half mirror 469, a coaxial camera 423 that captures the laser irradiation position from the direction coaxial with the laser beam, an image processing unit 475 that processes a captured image of the coaxial camera 423, and a stage based on the captured image Control to control position and angle, laser irradiation position, and laser output on / off And a (controller) 477.

  The coaxial camera 423, the laser irradiation device 467, the half mirror (beam splitter) 469, and the imaging device 471 can be moved in the vertical and horizontal height directions by the head transport XYZ robot 461. Thereby, the laser irradiation position is controlled.

  Further, the laser head sucks the BGA 100 to suck the component suction nozzle 353 that transports the BGA 100 from the tray 273 to the component mounting position and the laser beam that has come down vertically from the laser irradiation device 467 to the component suction nozzle 353. The mirror unit 451 for irradiating the bonded surface of the BGA 100 to the substrate 107, the bonded portion of the substrate 107 to the BGA 100, the exhaust device 357 for exhausting the melted solder paste and flux mist, and the BGA 100 substrate A height sensor 361 (such as a laser distance measuring sensor) that measures a position in the height direction from 107.

  The mirror unit 451 has upper mirrors 451a and 451b (the upper mirror 451b is a half mirror) for irradiating the joining surface to the substrate 107 of the BGA 100 adsorbed by the component adsorbing nozzle 353 with the vertically falling laser beam. And lower mirrors 451c and 451d for irradiating the joining portion of the substrate 107 to the BGA 100 with the laser beam that has descended vertically. The mirror unit 451 can move in the horizontal direction of the drawing, and the mirrors 451a to 451d move with the movement of the mirror unit 451.

  Further, the laser head includes a radiation thermometer 355b that measures the temperature of the joint portion of the BGA 100 to the substrate 107, and a radiation thermometer 355a that measures the temperature of the joint portion of the substrate 107 to the BGA 100. Soldering is performed after detecting that the temperature measured by these thermometers has reached the melting temperature of the solder.

  By sending the laser beam from the laser irradiation device 467 in the direction indicated by the solid line arrow, the plurality of solder balls 101 of the BGA 100 and the plurality of lands 103 of the substrate 107 (solder paste is applied) at a time. A laser beam can be irradiated.

  The imaging device 471 images a predetermined mark on the substrate 107 and detects the mounting position and direction of the BGA 100.

  The irradiation position of the laser is observed with a coaxial camera 423. Based on this, the control unit 477 adjusts the laser irradiation position so that the laser is irradiated to an appropriate position.

  In order to match the position of the solder ball 101 of the BGA 100 with the position of the land 103 of the substrate 107, the fiducial mark (recognition mark) of the substrate 107 is read by the imaging device 471, and the solder ball 101 of the BGA 100 is read. A method of reading the position with the camera unit 275 and aligning both can be employed. Alternatively, before or while heating the BGA 100 on the land 103 of the substrate 107 or during heating, the position of the solder ball 101 of the BGA 100 and the position of the land 103 of the substrate 107 with the coaxial camera 423 coaxial with the heating light source. And a method of aligning the two can be employed. Moreover, it is good also as employ | adopting these two methods together.

  Further, when both the solder balls 101 of the BGA 100 and the lands 103 of the substrate 107 are heated to the solder melting temperature or higher by light irradiation, the holding position of the BGA 100 is substantially vertically above the place where the lands 103 of the substrate 107 are located. It is desirable to hold substantially horizontally.

  In the present embodiment, heaters 353a and 359a are provided in a base 359 that conveys the suction nozzle 353 and the substrate 107. The heaters 353a and 359a are for preventing the temperature of solder or a portion to be soldered from decreasing after the heating by the laser is finished and before the soldering is performed. The heaters 353a and 359a are controlled by the controller 477.

  FIG. 11 is a view of the BGA 100 as viewed from the side where the plurality of solder balls 101 are provided.

  The laser irradiation area 101c (shown by hatching) is determined so as to cover all the rectangular areas where the solder balls 101 are present. Thereby, all the solder balls 101 can be dissolved simultaneously.

  Similarly, all lands on the substrate 107 located at positions corresponding to the solder balls are also irradiated with the laser beam. Thereby, all the solder paste on the land can also be dissolved.

  FIG. 12 is a diagram showing a process of performing soldering from the state where the solder is dissolved by the process of FIG.

  Prior to mounting the BGA, the height sensor 361 measures the distance between the BGA and the substrate joint. The stop position of the component suction nozzle 353 is determined by calculating the clearance (solder ball height + solder paste application thickness) necessary for solder joining.

  When the BGA is mounted, the mirror unit 451 is moved in the “A” direction in FIG. 12 to make a space between the BGA 100 and the substrate 107. The suction nozzle 353 carries the BGA 100 to the determined stop position (lowered in the “B” direction in FIG. 12). Thereafter, the BGA 100 is separated from the suction nozzle 353. Subsequent to the suction nozzle 353 separating the BGA 100, the suction nozzle 353 is moved away from the BGA 100 so as not to interfere with the self-alignment of the BGA 100. The BGA 100 is electrically connected to the substrate 107 as the solder temperature decreases.

  FIG. 13 is a flowchart illustrating an operation performed by the soldering apparatus according to the second embodiment.

  In the soldering apparatus according to the second embodiment, after the process shown in FIG. 5 is executed, the process shown in FIG. 13 is executed instead of the process shown in FIG. After the process shown in FIG. 13, the process shown in FIG. 7 is executed.

  In step S215, the mirror unit 451 is inserted between the BGA 100 and the substrate 107. In step S217, the solder balls 101 of the BGA 100 and the lands 103 of the substrate are heated with a laser so that the temperature is equal to or higher than the solder melting temperature. (State shown in FIGS. 10 and 11). At the same time, in step S218, the suction nozzle 353 and the base 359 for transporting the substrate 107 are heated by the heaters 353a and 359a. The temperature of the solder ball 101 and the land 103 is maintained at a temperature equal to or higher than the solder melting point by the processing in steps S217 and S218.

  In step S219, when it is confirmed by the radiation thermometers 355a and 355b that the solder ball 101 of the BGA 100 and the land 103 of the substrate are equal to or higher than the target temperature, the laser is stopped in step S221.

  In step S223, the mirror unit 451 between the BGA 100 and the substrate 107 is pulled out. Thereafter, in step S225, the BGA 100 is moved to the mounting position on the substrate 107 (state shown in FIG. 12).

  In step S227, the suction of the suction nozzle 353 is stopped, and the BGA 100 is separated from the suction nozzle 353. In step S228, heating by the heaters 353a and 359a is stopped. In step S229, the BGA 100 is soldered to the bonding position of the substrate by self-alignment.

  In the present embodiment, the solder ball 101 and the land 103 can be heated at once by a planar laser, and there is an effect that the temperature of the solder before soldering can be prevented from being lowered. Further, by using the heaters 353a and 359a, there is an effect that the temperature of the solder can be further prevented from decreasing. Such a heater may be provided in the apparatus according to the first embodiment.

  [Third Embodiment]

  FIG. 14 is a side view showing the configuration of the laser head in the third embodiment.

  This laser head can be used in place of the laser head of FIG. In the soldering apparatus, the substrate 107 is placed on a base (stage) 359 and conveyed from left to right in the drawing.

  As in the second embodiment, the laser head includes a head transport XYZ robot 461, a semiconductor laser light source 463, an optical cable (optical fiber) 465, a half mirror (beam splitter) 469, a laser irradiation device 467, an imaging device 471, and a coaxial camera 423. , Image processing unit 475, control unit (controller) 477, component suction nozzle 353, exhaust device 357, height sensor 361 (laser distance measuring sensor, etc.), base 359, heaters 353a and 359a, and radiation thermometers 355a and 355b. It has.

  The laser head in the third embodiment is different from that in the second embodiment in that the head conveyance XYZ is performed with the coaxial camera 423, the laser irradiation device 467, and the half mirror (beam splitter) 469 facing obliquely downward. It is attached to the robot 461. Further, a beam splitter 501 is provided instead of the mirror unit 451.

  One laser beam output from the laser irradiation device 467 strikes a beam splitter 501 provided in parallel with the substrate 107 and is divided into a beam traveling in an upward oblique direction and a beam traveling in a downward oblique direction.

  The beam traveling in the upward oblique direction is applied to the bonding surface of the BGA 100 adsorbed by the component adsorption nozzle 353 to the substrate 107. The beam traveling in the diagonally downward direction is applied to the joint portion of the substrate 107 to the BGA 100.

  When both the solder balls 101 of the BGA 100 and the lands 103 of the substrate 107 are irradiated with light, the holding position of the BGA 100 is preferably set substantially vertically above the place where the lands 103 of the substrate 107 are located, and the BGA 100 is preferably held substantially horizontally. .

  FIG. 15 is a diagram showing a process of performing soldering from the state where the solder is dissolved by the process of FIG.

  The BGA 100 is carried to the determined stop position by the suction nozzle 353 (lowered in the “B” direction in FIG. 15). Thereafter, the BGA 100 is separated from the suction nozzle 353. Subsequent to the suction nozzle 353 separating the BGA 100, the suction nozzle 353 is moved away from the BGA 100 so as not to interfere with the self-alignment of the BGA 100. The BGA 100 is electrically connected to the substrate 107 as the solder temperature decreases.

  FIG. 16 is a flowchart illustrating an operation performed by the soldering apparatus according to the third embodiment.

  In the soldering apparatus according to the third embodiment, after the process shown in FIG. 5 is executed, the process shown in FIG. 16 is executed instead of the process shown in FIG. After the process shown in FIG. 16, the process shown in FIG. 7 is executed.

  In step S315, the laser light guide optical system unit (laser irradiation device 467 and beam splitter 501) is disposed beside the BGA 100 and the substrate 107. In step S317, the solder balls 101 of the BGA 100 and the lands 103 of the substrate are heated with a laser so that the solder melting temperature is higher than the solder melting temperature (state of FIG. 14). At the same time, the suction nozzle 353 and the base 359 for transporting the substrate 107 are heated by the heaters 353a and 359a. Thereby, the temperature of the solder ball 101 and the land 103 is kept at a temperature equal to or higher than the solder melting point.

  In step S319, when it is confirmed by the radiation thermometers 355a and 355b that the solder ball 101 of the BGA 100 and the land 103 of the substrate are equal to or higher than the target temperature, the laser is stopped in step S320. Thereafter, in step S321, the BGA 100 is moved to a mounting position on the substrate 107 (state shown in FIG. 15).

  In step S327, the suction of the suction nozzle 353 is stopped, and the BGA 100 is separated from the suction nozzle 353. In step S329, the BGA 100 is soldered to the bonding position of the substrate by self-alignment.

  In the present embodiment, since the laser is irradiated obliquely, the step of moving the mirror unit as in the first and second embodiments can be omitted. For this reason, the time interval of soldering can be shortened. In addition, since it is not necessary to move the mirror unit after the solder is melted, soldering can be performed in a state where the temperature of the solder is high.

  [Fourth Embodiment]

  The laser head in the fourth embodiment is different from that in the third embodiment in that the processes in steps S320 and S321 in FIG. 16 are performed in the reverse order and the BGA is carried to the board mounting position. The point is to stop the laser.

  FIG. 17 is a diagram showing a process of performing soldering from a state where the solder is dissolved by the process of FIG.

  In the present embodiment, laser irradiation is performed while the BGA 100 is moved to the mounting position on the substrate 107 as compared with the third embodiment of FIG. Thereby, the solder ball 101 of the BGA 100 and the land 103 of the substrate can be heated as much as possible, and there is an effect that the soldering can be performed in a state where the solder temperature is high.

  [Fifth Embodiment]

  FIG. 18 is a side view showing the configuration of the laser head in the fifth embodiment.

  This laser head can be used in place of the laser head of FIG. In the soldering apparatus, the substrate 107 is placed on a base (stage) and conveyed from left to right in the drawing.

  In the third and fourth embodiments, one laser beam output from one laser irradiation device 467 is split by a beam splitter 501 to form two beams, and each beam is used as a solder ball of the BGA 100. 101 and the land 103 of the substrate were heated. On the other hand, in the fifth embodiment, two laser beams are output using the two laser irradiation devices 467a and 467b, and the solder balls 101 of the BGA 100 and the land 103 of the substrate are heated by the respective beams. To do.

  Semiconductor laser light sources 463a and 463b are provided as laser light sources of the two laser irradiation devices 467a and 467b. In addition, a mirror 601 is provided that reflects the laser beam from the laser irradiation device 467a to send the laser beam in the direction of the solder ball 101 of the BGA 100. The laser beam from the laser irradiation device 467b directly heats the land 103 of the substrate.

  FIG. 19 is a diagram showing a process of performing soldering from the state where the solder is dissolved by the process of FIG.

  When the solder ball 101 of the BGA 100 and the land 103 of the substrate reach a predetermined temperature, the BGA 100 is moved to the determined stop position by the suction nozzle 353 (lowered in the “B” direction in FIG. 19). At this time, simultaneously with the start of the movement of the BGA 100, the laser beam from the laser irradiation device 467a is turned off. The laser irradiation from the laser irradiation device 467b continues until the BGA 100 stops at the stop position.

  When the BGA 100 stops at the stop position, the BGA 100 is separated from the suction nozzle 353. Subsequent to the suction nozzle 353 separating the BGA 100, the suction nozzle 353 is moved away from the BGA 100 so as not to interfere with the self-alignment of the BGA 100. The BGA 100 is electrically connected to the substrate 107 as the solder temperature decreases.

  FIG. 20 is a flowchart showing the heat treatment in the two laser irradiation devices 467a and 467b in the fifth embodiment.

  In step S401, the laser irradiation devices 467a and 467b and the mirror 601 are aligned so that the laser strikes the solder ball 101 of the BGA 100 and the land 103 of the substrate. In step S403, laser irradiation is started, and heating of the solder balls 101 of the BGA 100 and the lands 103 of the substrate is started.

  In step S405, the radiation thermometers 355a and 355b measure the temperature of the solder ball 101 of the BGA 100 and the temperature of the land 103 of the substrate. In step S407, it is determined whether both the temperature of the solder ball 101 of the BGA 100 and the temperature of the land 103 of the substrate are equal to or higher than the temperature of (melting point of solder + α).

  If “YES” in the step S407, the laser irradiation of the laser irradiation device 467a is stopped in a step S409.

  In step S411, the BGA 100 is carried to the determined stop position by the suction nozzle 353 (set to a predetermined height from the substrate). Further, the laser irradiation of the laser irradiation device 467b is also stopped (Note that the laser irradiation of the laser irradiation device 467b may be stopped in step S409). In step S413, the BGA 100 is separated from the suction nozzle 353, and the suction nozzle 353 is moved away from the BGA 100 so as not to hinder the self-alignment of the BGA 100.

  On the other hand, if NO in step S407, that is, if either or both of the temperature of the solder ball 101 of the BGA 100 and the temperature of the land 103 of the substrate are lower than the temperature of (melting point of solder + α), the process proceeds to step S421. To do.

  In step S421, it is determined whether both the temperature of the solder ball 101 of the BGA 100 and the temperature of the land 103 of the board are equal to or lower than the heat resistance guarantee temperature of the component. If YES, heating by the laser is continued in step S423, and the process returns to step S405.

  If NO in step S421 (one of the temperature of solder ball 101 of BGA 100 and the temperature of land 103 of the substrate exceeds the heat resistance guarantee temperature of the component), the heat resistance guarantee temperature is exceeded in step S425. Stop the laser heating side. Thereafter, the process returns to step S405.

  Such a process has an effect that the temperature of the solder ball 101 of the BGA 100 and the temperature of the land 103 of the substrate are made higher than the melting point of the solder, but these temperatures do not exceed the heat resistance temperature of the component.

  [Control of temperature during soldering]

  FIG. 21 is a diagram for explaining temperature control in soldering.

  FIG. 21A is a graph showing the temperature change of the solder and the like in the case where laser irradiation is continued while the BGA 100 is lowered to the joining position by the suction nozzle 353 (FIGS. 17 and 19). FIG. 16 is a graph showing a change in solder temperature when laser irradiation is stopped before the BGA 100 is lowered to the bonding position by the suction nozzle 353 (FIGS. 4, 12, and 15).

  The horizontal axis of the graph shows time, time T1 is the time when laser irradiation is started, time T2 is the time when BGA 100 starts to be lowered to the bonding position, and time T3 is the distance between the BGA and the substrate is almost zero. Is shown.

  Also, (1) is the on / off of the laser output, (2) is the temperature of the solder ball 101 of the BGA 100, (3) is the temperature of the land 103 of the substrate (temperature of the solder paste on the land), and (4) is The distance between the BGA and the substrate is shown.

  In FIG. 21A, laser irradiation is continued after time T1 until time T4 when a predetermined time elapses after the distance between the BGA and the substrate becomes zero. Until the time T2 when the BGA 100 starts to be lowered to the joining position, the laser hits the solder ball 101 of the BGA 100, so the temperature of the solder ball 101 continues to rise until the time T2.

  After time T2, since the laser does not hit the solder ball 101 of the BGA 100, the temperature of the solder ball 101 decreases.

  On the other hand, until the time T3 when the distance between the BGA and the substrate becomes almost 0, the laser is applied to the land 103 of the substrate, so the temperature of the land 103 of the substrate (the temperature of the solder paste on the land) is until the time T3. Continue to rise. After time T3, since the laser does not hit the land 103 of the substrate, the temperature of the land 103 of the substrate decreases.

  On the other hand, in FIG. 21B, laser irradiation is continued from time T1 to time T2 at which the BGA 100 starts to be lowered to the bonding position.

  Until the time T2 when the BGA 100 starts to be lowered to the joining position, the laser hits the solder ball 101 of the BGA 100, so the temperature of the solder ball 101 continues to rise until the time T2. After time T2, since the laser does not hit the solder ball 101 of the BGA 100, the temperature of the solder ball 101 decreases.

  Similarly, until the time T2 when the BGA 100 starts to be lowered to the bonding position, the laser hits the land 103 of the substrate, so the temperature of the land 103 of the substrate (the temperature of the solder paste on the land) continues to rise until the time T2. After time T2, since the laser does not hit the land 103 of the substrate, the temperature of the land 103 of the substrate decreases.

  As described above, when the process of FIG. 21A is performed, the laser irradiation time to the land 103 of the substrate can be made longer than that of the process of FIG. There is an effect that can be.

  [Modification]

  In the above-described embodiment, the BGA is lowered to the board mounting position by the suction nozzle 353. However, after the solder is melted, the suction of the suction nozzle 353 is stopped and the BGA is dropped to the board mounting position. It is good also as soldering.

  Furthermore, the scanning speed (moving speed) and power of the laser beam may be controlled based on the melting point and size of the solder ball, the melting point and land size of the solder paste, and the like. Moreover, it is good also as irradiating a some beam simultaneously.

  In addition, since the size of the solder bump varies depending on the type such as BGA or CSP, laser beam size control (objective lens position control), beam intensity control, pulse wave frequency control, etc. may be executed.

  As the light source, a semiconductor laser, a xenon lamp, an infrared lamp, a carbon dioxide laser, a solid laser, or the like can be used.

  Moreover, although the example which heats an adsorption nozzle or a stage with a heater was shown, it is good also as preventing the temperature fall of the solder ball 101 of BGA100, or the land 103 of a board | substrate by sending a hot air around BGA or a board | substrate.

  Further, the laser beam may not be applied to a portion other than the solder joint portion of the BGA or CSP, or the laser beam may not be applied to a place other than the land on the substrate. If it does in this way, it will become possible to solder all the joining points, without heating an unnecessary part. Thus, soldering can be performed without applying a thermal load that would damage the IC circuit and without burning the substrate.

  In addition, it should be thought that the said embodiment is an illustration and restrictive at no points. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a top view which shows the structure of the soldering apparatus in the 1st Embodiment of this invention. It is a side view which shows the structure of the laser head 200 of FIG. It is the figure which looked at BGA100 from the side in which the some solder ball 101 was provided. It is a figure which shows the process which solders from the state which the solder melt | dissolved by the process of FIG. It is a flowchart which shows the operation | movement which a soldering apparatus performs. It is a flowchart following FIG. It is a flowchart following FIG. It is sectional drawing which shows the problem of the conventional construction method using a reflow furnace. It is a figure for demonstrating the effect (prevention of void generation | occurrence | production) in embodiment. It is a side view which shows the structure of the laser head in 2nd Embodiment. It is the figure which looked at BGA100 from the side in which the some solder ball 101 was provided. It is a figure which shows the process which solders from the state which the solder melt | dissolved by the process of FIG. It is a flowchart which shows the operation | movement which the soldering apparatus in 2nd Embodiment performs. It is a side view which shows the structure of the laser head in 3rd Embodiment. It is a figure which shows the process which solders from the state which the solder melt | dissolved by the process of FIG. It is a flowchart which shows the operation | movement which the soldering apparatus in 3rd Embodiment performs. It is a figure which shows the process which solders from the state which the solder melt | dissolved by the process of FIG. It is a side view which shows the structure of the laser head in 5th Embodiment. It is a figure which shows the process which solders from the state which the solder melt | dissolved by the process of FIG. It is a flowchart which shows the heat processing in the two laser irradiation apparatuses 467a and 467b in 5th Embodiment. It is a figure for demonstrating control of the temperature in soldering.

Explanation of symbols

100 BGA package 101 Solder ball 103 Land (after applying solder paste)
DESCRIPTION OF SYMBOLS 107 Substrate 200 Laser head 251 Substrate transport device 301 Imaging device 303 Semiconductor laser light source 307 Laser irradiation device 309 Half mirror 311, 313 Galvano mirror 315 Telecentric lens 323 Coaxial camera 325 Image processing unit 327 Control unit 351 Mirror unit 351a-351d Mirror 353 Parts Adsorption nozzle 355a, 355b Radiation thermometer 359a, 359b Heater

Claims (13)

A soldering method for connecting an electronic component and a board,
Solder is applied to at least one of the connection part of the electronic component to the substrate and the connection part of the substrate to the electronic component,
In a state where the electronic component and the substrate are separated from each other, a light irradiation step of irradiating light to a connection portion of the electronic component to the substrate and a connection portion of the substrate to the electronic component;
After the solder is melted by the light irradiation step, the distance between the electronic component and the substrate is shortened, thereby connecting the electronic component to the substrate, and the substrate to the electronic component. A soldering method comprising: soldering a connection portion with the solder.   The soldering method according to claim 1, wherein when the electronic component is mounted on the substrate, the connection portion to the substrate is substantially hidden.   3. The soldering method according to claim 1, wherein a flux is applied to both a connection portion of the electronic component to the substrate and a connection portion of the substrate to the electronic component.   In the soldering step, the electronic component is positioned on the bonding position of the substrate by a conveying member, and a distance between the electronic component and the substrate is set to a predetermined distance, and then the electronic component is transferred from the conveying member to the electronic component. The soldering method according to any one of claims 1 to 3, wherein a component is separated, and then the conveying member is moved away from the electronic component.   The position of the connection part of the said electronic component to the said board | substrate and the connection part of the said board | substrate to the said electronic component is aligned by the camera coaxial with the light irradiated at the said light irradiation process. The soldering method of crab.   The soldering method according to claim 1, wherein when performing light irradiation in the light irradiation step, the electronic component is held horizontally vertically above a bonding position of the substrate.   The soldering method according to claim 1, wherein the light source for light irradiation is a semiconductor laser, a xenon lamp, or an infrared lamp. There are a plurality of connection points to the substrate of the electronic component and connection points to the electronic component of the substrate, respectively.
The solder is provided at a plurality of locations as solder bumps,
The soldering method according to claim 1, wherein the light irradiation step irradiates a plurality of connection locations of the electronic component and a plurality of connection locations of the substrate with a galvanometer mirror.   The soldering method according to claim 1, wherein the light irradiation step performs irradiation with one or two beams. In the light irradiation step, further comprising a step of measuring the temperature of the position where the light is irradiated,
The soldering method according to any one of claims 1 to 9, wherein the soldering step performs soldering after detecting that the temperature measured in the step of measuring the temperature becomes a melting temperature of the solder.   The soldering method according to claim 1, wherein at least one of the electronic component and the substrate is heated before the soldering.   A method for producing a mounting board, wherein a board on which electronic components are mounted is produced by the soldering method according to claim 1. A soldering device for connecting an electronic component and a board,
Solder is applied to at least one of the connection part of the electronic component to the substrate and the connection part of the substrate to the electronic component,
In a state where the electronic component and the substrate are separated from each other, a light irradiation mechanism for irradiating light to a connection portion of the electronic component to the substrate and a connection portion of the substrate to the electronic component,
After melting the solder by the light irradiation, by shortening the distance between the electronic component and the substrate, the connection location of the electronic component to the substrate, and the connection of the substrate to the electronic component A soldering apparatus comprising: a mechanism for soldering a portion with the solder.

Images