JP2011009243A - Method of melting solder, method of manufacturing packaging substrate, and solder melting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of melting solder, appropriately melting solder for connecting electronic components to a substrate.SOLUTION: When n×n solder balls of BGA (Ball Grid Array) are disposed in vertical and horizontal directions, laser beams are applied at an angle ("A" in the figure) inclined by an angle θ to an array direction of the solder balls. The laser beams are applied to all the solder balls by moving irradiation points of the laser beams to a direction ("B" in the figure) crossing the direction "A".

Description

  The present invention relates to a solder melting method, a mounting board production method, and a solder melting apparatus, and more particularly to a solder melting method for melting solder for connecting an electronic component and a board, a mounting board production method, and a solder melting 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 called BGA (Ball Grid Array), CSP (Chip Size Package) and the like in the form of components.

  Soldering of electronic components to a 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 for joining mounted components by light energy irradiation, there are techniques shown in Patent Documents 1 to 3 below.

  Patent Document 1 discloses a processing method for heating cream solder at the lower part of a component without applying thermal stress to the component by irradiating light energy from obliquely above the component by adjusting an optical system.

  Patent Document 2 discloses a device reproduction method in which a mirror is used to irradiate a junction between a semiconductor device and a substrate with a pulse beam shaped linearly with a cylindrical lens.

Patent Document 3 discloses a method of melting a solder by irradiating light from the back surface of a substrate having laser light transparency and joining a mother substrate and an electronic component.
Japanese Patent No. 3622714 JP 2002-280726 A JP 2005-347610 A

  The technique of Patent Document 1 has the following problems. The gap between the component and the printed circuit board is narrow, and the joints are arranged like a grid. For this reason, light does not reach the entire joint by irradiation from obliquely above. Therefore, there is a problem that the solder cannot be melted and joined at all the joining points. Further, when BGA or CSP having a bonding surface on the back surface is irradiated with light energy from the component surface, there is a problem that a thermal load is applied to the IC circuit.

  In the method of Patent Document 2, the laser is irradiated from between the semiconductor device and the substrate toward the bonding portion. However, there is a problem that the bonding portions in the second row and after enter the shadow of the bonding portion in the front row. is there. For this reason, it is impossible to uniformly dissolve the joint.

  The technique of Patent Document 3 has the following problems. Recently, multilayer boards have been used due to demands for higher density, and double-sided mounting is often used as a mounting method. Therefore, there is a problem that it is difficult to perform laser irradiation from the back surface of the substrate because parts and wiring are in the way. Moreover, the technique of patent document 3 cannot be used for a rigid glass epoxy substrate. The transmittance of visible light and near infrared light in a glass epoxy substrate is only about 2% for a 1 mm thick substrate. For this reason, most of the laser light is absorbed by the substrate, and the substrate is thermally damaged before the solder melts.

  The present invention has been made to solve such problems, and a solder melting method, a mounting substrate production method, and a solder capable of appropriately melting solder for connecting an electronic component and a substrate. It aims to provide a melting device.

Means for Solving the Problems and Effects of the Invention

  In order to achieve the above object, according to one aspect of the present invention, in a solder melting method for melting solder for connecting an electronic component and a substrate, a plurality of vertical and horizontal directions are provided between the electronic component and the substrate. Solder bumps are arranged. The solder melting method includes a step of melting a plurality of solder bumps by irradiating laser light from a gap between an electronic component and a substrate. In the melting step, laser light is irradiated from an angle inclined with respect to the solder bump arrangement direction.

  According to the present invention, the laser beam can be irradiated from an angle inclined with respect to the arrangement direction of the solder bumps. Thereby, each of the plurality of solder bumps arranged in the vertical direction and the horizontal direction can be irradiated with laser light, and the plurality of solder bumps arranged in the vertical direction and the horizontal direction can be appropriately dissolved. effective.

  Preferably, the solder melting method sequentially irradiates a plurality of solder bumps with laser light by moving the irradiation point of the laser light.

  In this case, there is an effect that a plurality of solder bumps arranged in the vertical direction and the horizontal direction can be sequentially dissolved.

  Preferably, the solder melting method controls the output of the laser light in accordance with how the laser light strikes each solder bump when moving the laser light irradiation point.

  In this case, there is an effect that a preferable laser beam can be output to each solder bump.

  Preferably, the height of the laser beam is set to a size equal to or smaller than the gap between the electronic component and the substrate.

  In this case, the gap between the electronic component and the substrate can be passed through the laser beam, and the effect of the laser on the electronic component and the substrate can be reduced as much as possible.

  Preferably, the laser beam is irradiated so as to be parallel to the main surface having the bonding portion of the substrate.

  In this case, it becomes easy to irradiate the laser only to the solder bump, and there is an effect that the influence of the laser on the electronic component and the substrate can be reduced as much as possible.

  When the other aspect of this invention is followed, the production method of a mounting board | substrate will produce the board | substrate with which the electronic component was mounted using the solder melting method in any one of the above-mentioned.

  According to the present invention, it is possible to satisfactorily produce a substrate on which electronic components are mounted by appropriately dissolving a plurality of solder bumps arranged in the vertical and horizontal directions.

  According to still another aspect of the present invention, in a solder melting apparatus for melting solder for connecting an electronic component and a substrate, a plurality of solder bumps are provided in the vertical and horizontal directions between the electronic component and the substrate. Arranged. The solder melting device irradiates laser light from the gap between the electronic component and the substrate to melt a plurality of solder bumps, and laser light from an angle inclined with respect to the solder bump arrangement direction. And a control device for controlling the irradiation direction of the laser light.

  According to the present invention, there is an effect that it is possible to provide a solder melting apparatus capable of appropriately melting a plurality of solder bumps arranged in the vertical direction and the horizontal direction.

  Preferably, the solder melting device further includes a substrate carrying device for carrying a substrate on which electronic components are placed, and the laser beam irradiation device directs the laser generator and the laser emitted from the laser generator to the solder bumps. A reflecting portion for reflecting.

  In this case, there is an effect that the work can be efficiently performed by transporting the substrate and the laser beam can be easily irradiated.

  Preferably, the reflection part includes a prism, and an acute angle of the prism is directed to the substrate side.

  In this case, the prism can be prevented from coming into contact with other components on the substrate.

  Preferably, the solder melting apparatus further includes: a first imaging device that images the board on which the electronic component is placed; and an identification unit that identifies the position of the electronic component based on the image captured by the first imaging device. Prepare.

  In this case, since the position of the electronic component can be identified, there is an effect that the dissolution control of the solder can be performed more appropriately.

  Preferably, the solder melting apparatus further includes a second imaging device that captures an irradiation position of the laser light, and the laser light irradiation device controls laser irradiation based on an image captured by the second imaging device. .

  In this case, since the laser irradiation can be controlled based on the irradiation position of the laser beam, there is an effect that the melting of the solder can be appropriately controlled.

  Below, the soldering method by laser irradiation from the side surface of BGA and LGA (Land Grid Array) as an example of back junction electronic components in an embodiment of the present invention is explained. In addition, although soldering is mentioned here as an example, the present invention can be used also when extending the lifetime of a junction part by solidifying after the soldering part is melt | dissolved again after soldering of an electronic component. .

  [About soldering method]

  FIG. 1 is a cross-sectional view for explaining an outline of a soldering method according to one embodiment of the present invention.

  Here, a state in which a BGA (or CSP or the like) 100 is electrically bonded to the copper land 105 formed on the glass epoxy substrate 107 using the solder ball 101 and the solder paste 103 is shown. The diameter of the solder ball 101 associated with the BGA is indicated by Φd, and the interval between the solder balls is indicated by the pitch P. Further, the distance between the bottom of the package resin of the BGA 100 and the surface of the substrate 107 is indicated by h1.

  The position of the prism is controlled so that the acute angle portion 201a of the prism 201 having an isosceles triangle shape is located in the vicinity of the BGA 100 on the substrate 107 when viewed from the side. The laser beam L irradiated from above the substrate 107 is reflected by the prism 201 and irradiated onto the solder balls 101 and the solder paste 103. The dimension (thickness) in the height direction of the laser beam L reflected by the prism 201 is adjusted to be h1 or less (or solder ball diameter Φd (bump height) or less). The cross-sectional shape of the laser beam L may be a circle as shown in the cross-section L1, or may be an ellipse as shown in the cross-section L2.

  As shown in the figure, the laser beam L reflected by the prism 201 at an angle of 90 ° proceeds in parallel to the main surface of the substrate 107, enters the gap between the substrate 107 and the bottom of the package resin portion of the BGA 100, The solder balls 101 and the solder paste 103 are irradiated. As a result, the solder balls 101 and the solder paste 103 are dissolved and soldering is performed.

  Note that a mirror capable of reflecting the laser beam may be used instead of the prism.

  FIG. 2 is a cross-sectional view for explaining an outline of a soldering method in one embodiment of the present invention.

  Here, a state in which an LGA (or FLGA (Fine-pitch Land Grid Array) 151) 151 is electrically bonded to the copper land 105 formed on the glass epoxy substrate 107 using the solder paste 103 is shown. . The diameter of the copper lands 105 is indicated by Φd, and the interval between the copper lands 105 is indicated by the pitch P. Further, the interval between the bottom of the package resin portion of the LGA 151 and the surface of the substrate 107 is indicated by h2.

  Also in this method, similarly to the case of FIG. 1, the laser beam is irradiated onto the solder paste 103 by reflecting the laser beam irradiated from above the substrate 107 using a prism. The dimension (thickness) in the height direction of the laser beam reflected by the prism is adjusted to be equal to or less than h2. The cross-sectional shape of the laser beam L may be a circle as shown in the cross-section L3 or an ellipse as shown in the cross-section L4.

  The laser beam reflected by the prism enters the gap between the substrate 107 and the bottom of the package resin portion of the LGA 151 and is applied to the solder paste 103. As a result, the solder paste 103 is melted and soldering is performed.

  In FIGS. 1 and 2, when the laser beam is parallel light, the irradiation direction of the laser beam is controlled so that the laser beam travels parallel or substantially parallel to the substrate 107. When the laser beam is not parallel light (when it is convergent light or diffused light), the lower end of the laser beam is parallel to or slightly upward with respect to the main surface having the joint portion of the substrate 107, and The irradiation direction of the laser beam is controlled so that the upper end of the laser beam is parallel to the lower surface of the BGA 100 or slightly downward.

  FIG. 3 is a plan view for explaining an outline of a soldering method in one embodiment of the present invention.

  Here, as an example of the solder bump, a state where n × n BGA solder balls (indicated by hatched circles) are arranged in the vertical and horizontal directions is shown. In FIG. 3, n = 10. For convenience, the position of the lower left solder ball is (X, Y) = (1, 1), and the X axis is set to the right and the Y axis is set to the upper. The position of the upper right solder ball is (X, Y) = (10, 10). The solder ball at the position Y = 1 is the frontmost solder ball as viewed from the laser irradiation direction, and the solder ball at the position Y = 10 is the last solder ball. The interval (pitch) between the solder balls is P, and the diameter of the solder balls is Φd.

  When the laser beam is irradiated in the same direction as the solder ball arrangement direction (Y-axis direction indicated by the alternate long and short dash line), the laser beam is irradiated to the solder ball at Y = 1, but at Y = 2-10. Certain solder balls in the second and subsequent rows from the laser beam irradiation source (solder balls on the back side from the irradiation source) are hidden by the solder balls at the position of Y = 1. Therefore, the solder ball at the position of Y = 2 to 10 is not melted without being irradiated with the laser beam.

  Therefore, in this embodiment, the laser beam is irradiated from an angle inclined by an angle θ with respect to the solder ball arrangement direction as indicated by “A” in the drawing. By moving the laser beam irradiation point in the direction “B” perpendicular to the direction “A” (or the direction intersecting the “A” direction such as the X-axis direction), all the solder balls are irradiated with the laser beam. So that That is, even if the laser beam width W1 (FIG. 1) is much smaller than the BGA width, the BGA width can be covered by the movement of the laser beam irradiation point.

  FIG. 4 is a view in the “A” direction in FIG. 3.

  A part of the nine solder balls on the rear side of the solder ball B2 is observed between the solder balls B1 and B2 in FIG. 3 (this interval is represented by P cos θ). That is, by irradiating the laser beam in the “A” direction of FIG. 3, it is possible to give energy to all the solder balls and dissolve them.

  As shown in FIG. 3, the angle θ is such that the laser beam trajectory connects the right end of the solder ball at the position (X, 1) and the left end of the solder ball at the position (X + 1, 10). By setting in this way, it is possible to irradiate all the solder balls with the laser beam, and to increase the irradiation area of the laser beam onto the solder balls as much as possible.

  The angle θ is preferably about 0 ° <θ <45 °. This is because if θ is 0 °, the solder balls in the second and subsequent rows from the laser beam irradiation source are hidden behind the frontmost solder ball. Further, when θ is 45 °, the solder ball at the position (X + 1, Y + 1) is hidden behind the solder ball at the position (X, Y).

  In FIG. 3, the angle of the laser beam is tilted θ to the right from the direction indicated by the alternate long and short dash line, but it may be tilted θ to the left. In this case, if θ is set so that the trajectory of the laser beam connects the left end of the solder ball at the position (X, 1) and the right end of the solder ball at the position (X-1, 10), all The solder ball can be irradiated with a laser beam, and the area of the solder ball irradiated with the laser beam can be made as large as possible.

  The light used for melting the junction point may be parallel light, convergent light, or diffused light.

  As described above, in the present embodiment, the laser beam is narrowed down to the gap between the component and the substrate, and is irradiated almost parallel to the substrate. Further, the laser beam is irradiated at an angle with respect to the array of joint points arranged like a grid so that the light reaches the deepest joint point. Thereby, the junction of all the lines can be heated and melted.

  [First configuration of soldering apparatus]

  FIG. 5 is a plan view showing a first configuration of a soldering apparatus for performing soldering by executing the above-described soldering method.

  Referring to the figure, the soldering apparatus includes a board transport apparatus 251 that transports the board 107 on which the BGA or the like is placed on the base to a position indicated by a position 107 ', and an XY above the base. And a laser irradiation device (head device) 200 movable along a plane.

  The soldering apparatus includes a driving device 271 that moves the laser irradiation device 200 in the X direction, the Y direction, and the R (rotation) direction.

  The laser irradiation apparatus 200 includes a support that supports a prism that reflects the emitted laser beam, an R-axis drive function that rotates the prism relative to the support, and a Z-axis drive function that moves the prism up and down relative to the support. With.

  The laser irradiation apparatus 200 has a function of moving the incident position of the laser beam on the prism in the XY direction or the horizontal direction.

  6 is a plan view of a part of the laser irradiation apparatus 200 of FIG. 5, and FIG. 7 is a side view of a part thereof.

  As shown in the drawing, the laser irradiation apparatus 200 includes a laser irradiation apparatus 253 provided above, a driving apparatus 255 that moves the laser irradiation position of the laser irradiation apparatus 253 relative to the position of the prism, and the laser irradiation apparatus 253. A prism (light transmitting body) 201 that reflects the emitted laser beam L at an angle of 90 °, and a piezo motor 209 that adjusts the angle in the height direction of the laser by rotating the prism 201 about the axis 209 ′; 6, a driving device 211 that drives the prism in the horizontal direction in FIG. 6, a height sensor 215 that detects the height of the prism from the substrate, a protective glass 203 for preventing the prism from being contaminated by solder flux, A protective cover 205 for preventing the laser beam from leaking from the prism and an exhaust nozzle 207 are provided.

  The laser irradiation apparatus 200 has a structure in which the angle of the reflecting surface of the prism can be finely adjusted, so that the laser light can be delivered deep into the BGA. Further, even if the parallelism of a component such as a BGA varies with respect to the reference plane due to deflection of the printed circuit board, the laser light path can be adjusted.

  If the surface of the prism 201 or the surface of the protective glass 203 becomes dirty due to the scattering of the flux, the laser is absorbed by the dirt. For this reason, in the soldering apparatus, an exhaust nozzle 207 is provided to create an air flow and prevent the scattered matter from adhering. That is, in FIG. 6, air is sucked in the “E” direction. The exhaust nozzle 207 has an effect that the laser irradiation condition is kept constant and the soldering quality is stabilized.

  The laser irradiation device 253 may include a laser irradiation unit and a laser generation device that supplies a laser to the laser irradiation unit via a flexible optical cable.

  As shown in the figure, the lower end of the prism has a reflecting surface that bends the laser light from above so as to pass through a surface parallel to the substrate.

  FIG. 8 is a plan view showing a state where soldering is performed by a soldering apparatus.

  In the BGA 100, a plurality of solder balls 101 indicated by dotted circles are arranged in the vertical and horizontal directions. With the prism 201 lowered to the vicinity of the substrate, the laser beam is irradiated in the “A” direction (the direction of the white arrow) aiming at the gap between the BGA and the substrate. As shown in FIG. 3, this direction is an angle inclined with respect to the solder ball arrangement direction (Y direction).

  Further, the drive device 255 changes the laser incident position with respect to the position of the prism in the “B” direction (the direction of the black arrow and orthogonal to “A”) so that all the solder balls are irradiated with the laser beam, Further, the prism itself is also moved in the “B” direction by the driving device 211.

  In this way, all the solder balls can be dissolved and soldered to the BGA substrate.

  In FIG. 8, if the area where the solder balls of the BGA 100 are present is covered by the width of the prism, the prism need not be moved. In this case, all the solder balls can be dissolved simply by moving the laser incident position on the prism.

  [Second configuration of soldering apparatus]

  FIG. 9 is a side view showing a second configuration of a soldering apparatus for performing soldering by executing the above-described soldering method, and FIG. 10 is a plan view showing a laser irradiation apparatus (head apparatus) surrounding the BGA. It is.

  In the soldering apparatus, the substrate 107 is placed on a stage (not shown). By soldering the solder balls 101 of the BGA 100 on the substrate 107 from the side, soldering is performed.

  In the present embodiment, laser irradiation apparatuses 200A to 200D corresponding to the four sides of the BGA are provided. Thereby, a laser can be irradiated from 4 directions to BGA. Therefore, in the configuration shown in FIG. 8, it is possible to easily irradiate the laser to the solder balls that are difficult to reach by the laser.

  As shown in FIG. 9, the soldering apparatus includes a laser irradiation unit 307, a laser generator 303 that supplies a laser to the laser irradiation unit 307 via a flexible optical cable 305, and a laser from the laser irradiation unit 307. The galvanometer mirrors 311 and 313 for reflecting the beam after passing through the half mirror 309 and scanning the laser beam, the telecentric lens 315 for irradiating the laser beam from the galvanometer mirror directly downward, 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 , Coaxial camera for photographing laser irradiated position from the same direction as the laser beam 323, an image processing unit 325 that processes a captured image of the coaxial camera 323, and a control unit 327 that controls on / off of the stage position and angle, the prism position and angle, and the laser output based on the captured image. .

  The soldering apparatus includes drive units 261A and 261B that move the laser irradiation devices in the XYR directions, and drive units 263A and 263B that move the laser irradiation devices in the height direction.

  The laser beam is guided to the track LA by the action of the galvanometer mirror and soldered by the laser irradiation device 200A, then the laser beam track is switched, the laser beam is guided to the track LB, and soldering is performed by the laser irradiation device 200B. .

  The imaging device 301 images a predetermined mark or electronic component on the board and detects the position and direction of the electronic component. Based on the detection result, the control unit 327 moves the prism to a predetermined position of XYR with respect to the electronic component.

  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 with respect to the electronic component so that the laser is irradiated to an appropriate position.

  The soldering apparatus in the second configuration can accommodate various sizes of BGA and the like by assembling the four prisms of FIG. 10 into squares so that they can be moved freely. In addition, the size of the prism can be reduced by moving the prism in conjunction with the movement of the laser. Thereby, even if it is a high-density mounting substrate, it can prevent as much as possible that a prism collides with other adjacent components.

  In addition, as shown in FIG. 9, since the acute angle portion of the isosceles triangle of the prism is located on the substrate side, it is possible to prevent the prism from colliding with other adjacent components even in high-density mounting where the distance between the components is narrow. .

  With respect to the laser irradiation apparatus shown in FIG. 10, for example, the laser beam is irradiated onto the prisms of the respective laser irradiation apparatuses in the order of 200A → 200D → 200B → 200C. Thereby, the laser beam is irradiated so as to make a round around the BGA, and soldering is performed.

  FIG. 11 is a diagram for explaining an image of a solder ball photographed by the coaxial camera 323 and control of laser irradiation.

  Here, as in FIG. 4, a state is shown in which the solder balls B <b> 1 and B <b> 2 at the head (first row) with respect to the irradiation position are photographed. In the second configuration of the soldering apparatus, since the laser is irradiated from the four sides of the BGA, it is necessary to irradiate the laser beam to the solder balls in the last row (Y = 10 row) as shown in FIG. Absent. Accordingly, in FIG. 11, the angle θ is made larger than that in FIG. 3, and the three or more solder balls behind the solder ball B2 are hidden behind the solder ball B1. The solder balls hidden behind the shadows of the solder balls B1 are given sufficient energy when irradiated with a laser beam from the opposite direction.

  In FIG. 11, the width of the laser beam is indicated by hatching (width L) with reference to the symbol “C”. By moving the laser irradiation width to the right, the solder balls are sequentially irradiated with laser. By simply moving the laser irradiation width, the energy applied to the solder balls B1 and B2 in the first row becomes excessive compared to the solder balls that are shadows of the solder balls B1 and B2 in the first row.

  Therefore, in the present embodiment, when the laser hits the outer solder ball so that the laser irradiation amount is uniform, the laser emission is temporarily stopped during the movement of the laser irradiated position. As a result, the cumulative amount of laser energy received by each solder ball is made close to uniform. The stop timing of laser emission may be set at the time of teaching, or the control unit 327 may recognize the image captured by the coaxial camera and obtain the stop timing.

  In FIG. 11, a laser pause area (hatched portion) having a width of ½ of the radius of the solder ball is assumed in each of the left and right directions from the center of the images B1 and B2 of the frontmost solder balls. When the center “C” of the laser beam is present, the laser emission is stopped. Thereby, the laser irradiation is repeatedly turned on / off as shown in the lower timing chart of FIG. That is, the laser is turned off when the center “C” of the laser beam reaches the portion A of the hatching, and the laser is turned on again when it passes the portion B of the hatching.

  By such control, it is possible to reduce the difference in the amount of laser irradiation between the outer peripheral solder ball that is easily hit by the laser beam and the solder ball that is hard to hit the laser beam inside.

  The soldering apparatus takes in board data (mounting component type, mounting position, mounting direction) and solder bump data, and performs corresponding laser beam irradiation. Prior to actual beam irradiation, positioning of the prism device (X and Y positioning, R positioning by angle selection, Z positioning based on the size of the bump) is performed.

  In addition, in order to deal with the positional deviation at the time of mounting, the positional deviation of the component with reference to the mark on the board is confirmed by the imaging device 301 (or an upstream inspection machine), and the position is corrected with reference to the board mark based on this data To do.

  Alternatively, the position of the electronic component relative to the base may be detected, and the component may be positioned based on this position (direct position is determined instead of correction).

  A soldering apparatus carries in a board | substrate, images the mark of a board | substrate, and performs XYR positioning of a prism. Thereafter, the Z is positioned simultaneously with lowering the prism. When laser irradiation is started, the laser irradiation position is moved with respect to the prism. After a predetermined time has elapsed, laser irradiation is stopped.

  After performing the same routine on a plurality of sides of the BGA, the prism is raised and the prism position of the laser irradiation device is returned. If there is another part to be soldered, the same applies. When soldering is completed, the board is unloaded and a new board is loaded.

  FIGS. 12-14 is a flowchart which shows the operation | movement which the soldering apparatus in a 2nd structure performs.

  In step S101, the board on which the component is mounted is supplied to a soldering place. In step S103, the position of the BGA is confirmed by the imaging device 301 (mounting part imaging camera). In step S105, the BGA position data is corrected.

  In step S107, the laser irradiation device (head device) is moved to the position of the BGA based on the corrected position data. In step S109, the installation position of the prism, the laser irradiation angle to the BGA, and the laser irradiation range (BGA size) are determined based on the separately input component information.

  In step S111, the driving device (XYR stage) moves the prism to a predetermined position. In step S113, the prism is lowered to a position near the substrate. At this time, the prism is stopped at a predetermined position by using the height sensor 215.

  In step S115, the galvanometer mirror is driven without irradiating the laser, and the prism is moved so that the side surface of the BGA can be seen through the prism. Also, by analyzing the image of the coaxial camera, the prism angle is finely adjusted with a piezo motor so that the laser beam strikes the center of the solder ball in the height direction.

  In step S117, the laser optical axis is moved to the laser irradiation start point for the BGA. The four prisms of the four laser irradiation devices are horizontally moved in the laser irradiation start direction on each side of the BGA without changing the height.

  In step S119, the laser is emitted with a predetermined output. The laser is scanned along the BGA at a predetermined speed. The prism is moved horizontally in accordance with the movement of the laser beam.

  In step S121, an image of the solder ball ahead in the direction of laser irradiation is captured by the coaxial camera. The captured image is analyzed, and laser rest areas having a half of the solder ball radius are determined from the center position of the outermost peripheral solder ball to the left and right, respectively. Note that the size of the rest area is determined by the BGA specification.

  In step S123, the laser is temporarily stopped when the center of the laser beam reaches the laser pause area. In step S125, when the center of the laser beam passes through the laser pause area, the laser is driven and emission is resumed.

  In step S127, an image of the solder ball ahead in the direction of laser irradiation is captured by the coaxial camera. The captured image is analyzed, and when there is no solder ball in the front, the laser is stopped. Thereafter, the laser irradiation start point is moved to that position on the adjacent side.

  In step S129, the prism is horizontally moved to the original position.

  In step S131, when a predetermined number of times of laser irradiation have been completed on each side of the BGA, the laser is stopped and the optical axis is returned to the initial position. In step S133, the prism is moved horizontally to return to the initial position. In step S135, the prism is lifted upward and returned to the initial position.

  In step S137, the laser irradiation apparatus is moved to the next BGA position. In step S139, laser soldering of components other than BGA is performed.

  In step S141, the substrate is ejected when the laser irradiation to all the programmed parts is completed. In step S143, the laser irradiation device and the prism are returned to the initial positions.

  [Laser irradiation angle]

  FIG. 15 is a diagram for explaining a method of setting the angle of the laser beam with respect to the arrangement direction of the solder bumps.

  As described above, when the laser beam is emitted in the same direction “F” (θ = 0 °) as the solder bump arrangement direction, the laser beam does not reach the solder bump of Y ≧ 2 due to the solder bump in the front row. Absent. Further, when a laser beam is emitted in a direction “A” (θ = 45 °) of 45 ° with respect to the solder bump arrangement direction, the coordinates (2) are generated by the solder bump of coordinates (X, Y) = (1, 1). , 2) This is not preferable because the laser beam does not reach the solder bumps.

  When a laser beam is emitted in a direction “B” connecting the solder bump center at coordinates (1, 1) and the solder bump center at coordinates (2, 3), the coordinates (1, 1) The laser beam does not reach the solder bumps 2 and 3). Similarly, for the direction “C” connecting the solder bump center at coordinates (1,1) and the solder bump center at coordinates (2,4), the coordinates (2,4) The laser beam does not reach the solder bumps.

  Therefore, as shown in FIG. 8, if the BGA is irradiated with the laser from only one direction, the solder bump at an angle (position (1, 1)) where the rear solder bump is completely hidden by the front solder bump. It is desirable not to set the center and the solder bump center at the position (m, n) (m and n are each an integer of 2 or more) in the laser irradiation direction.

  Further, when the laser is irradiated from four directions as shown in FIG. 10, it is desirable to determine the laser irradiation direction so that the laser reaches at least a solder bump located at Y ≦ 5. When the number of solder bumps in the Y direction is N, when N is an even number, the laser reaches at least a solder bump at a position of Y ≦ (1/2) N. When N is an odd number, It is desirable to determine the laser irradiation direction so that the laser reaches at least the solder bump at the position of Y ≦ (1/2) N + 1.

  [Modification]

  When the beam central axis is tilted with respect to the solder bump arrangement direction, the prism device itself may be tilted, or the bump arrangement direction may be tilted by tilting the substrate on the base.

  Further, the present invention can be carried out if at least a part of the irradiated beam is inclined with respect to the solder bump arrangement direction. For example, when the beam is diffused light or convergent light, the present invention can be implemented if a part of the laser beam to be irradiated is inclined.

  Furthermore, the scanning speed (moving speed) of the laser beam may be controlled based on the melting point or size of the solder bump. Moreover, it is good also as irradiating a several beam simultaneously (for example, simultaneously irradiating an opposite side).

  In addition, since the size of solder bumps varies depending on the type of BGA and CSP, prism device position control, laser beam size control (objective lens position control), beam intensity control, pulse wave frequency control, etc. are adopted. May be.

  Furthermore, the matrix size of the spherical solder bumps and the bump pitch vary depending on the component type. For this reason, it is desirable to perform irradiation angle control corresponding to the type, laser beam movement distance control, and the like.

  Also, simultaneously with the soldering from the BGA side surface, the soldering processing time can be shortened by irradiating and heating the BGA surface with a weak laser. In addition, the difference in the amount of heat received between the outer and inner solder balls is alleviated.

  [Effects of the embodiment]

  With the above configuration, it is possible to solder all joint points without heating the portion other than the solder joint portion of the BGA or CSP or the substrate. Thus, soldering can be performed without applying a thermal load that would damage the IC circuit and without burning the substrate.

  Moreover, since optimal irradiation can be performed for each part, the defect rate can be reduced.

  [Others]

  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 sectional drawing for demonstrating the outline of the soldering method in one of the embodiment of this invention. It is sectional drawing for demonstrating the outline of the soldering method in one of the embodiment of this invention. It is a top view for demonstrating the outline of the soldering method in one of the embodiment of this invention. FIG. 4 is a view in the “A” direction in FIG. 3. It is a top view which shows the 1st structure of the soldering apparatus which performs the soldering method and performs soldering. FIG. 6 is a plan view of a part of the laser irradiation apparatus 200 of FIG. 5. FIG. 6 is a side view of a part of the laser irradiation apparatus 200 of FIG. 5. It is a top view which shows the state in which soldering is performed by the soldering apparatus. It is a side view which shows the 2nd structure of a soldering apparatus. It is a top view which shows the laser irradiation apparatus (head apparatus) surrounding BGA. It is a figure for demonstrating the image of the solder ball which the coaxial camera 323 image | photographs, and control of laser irradiation. It is a flowchart which shows the operation | movement which the soldering apparatus in a 2nd structure performs. It is a flowchart following FIG. It is a flowchart following FIG. It is a figure for demonstrating the setting method of the angle of the laser beam with respect to the arrangement direction of a solder bump.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 BGA package 101 Solder ball 103 Solder paste 105 Copper land 107 Glass epoxy board | substrate 151 LGA package 200,200A-200D Laser irradiation apparatus 201 Prism 203 Protective glass 205 Protective cover 207 Exhaust nozzle 209 Piezo motor 211 Drive apparatus 215 Height sensor 251 Board conveyance Device 253 Laser irradiation device 255 Driving device 301 Imaging device 303 Laser generator 305 Optical cable 307 Laser irradiation unit 309 Half mirror 311, 313 Galvano mirror 315 Telecentric lens 317a, 317b Lens drive system 323 Coaxial camera 325 Image processing unit 327 Control unit B1, B2 Solder ball L Laser beam P Solder bump pitch θ Laser irradiation angle

Claims (11)

A solder melting method for melting solder for connecting an electronic component and a substrate,
Between the electronic component and the substrate, a plurality of solder bumps are arranged in the vertical direction and the horizontal direction,
Irradiating a laser beam from a gap between the electronic component and the substrate to dissolve the plurality of solder bumps;
In the melting step, a solder melting method in which laser light is irradiated from an angle inclined with respect to the arrangement direction of the solder bumps.   The solder melting method according to claim 1, wherein the laser beam is sequentially irradiated to the plurality of solder bumps by moving the irradiation point of the laser beam.   The solder melting method according to claim 2, wherein the laser light output is controlled according to how the laser light strikes each solder bump when moving the laser light irradiation point.   The solder melting method according to claim 1, wherein a height of the laser beam is set to a size equal to or smaller than a gap between the electronic component and the substrate.   5. The solder melting method according to claim 1, wherein the laser light is irradiated so as to be parallel to a main surface having a joint portion of the substrate.   A method for producing a mounting board, wherein a board on which electronic components are mounted is produced by the solder melting method according to claim 1. A solder melting apparatus for melting solder for connecting an electronic component and a board,
Between the electronic component and the substrate, a plurality of solder bumps are arranged in the vertical direction and the horizontal direction,
A laser beam irradiation device for melting the plurality of solder bumps by irradiating a laser beam from a gap between the electronic component and the substrate;
A solder melting apparatus comprising: a control device that controls an irradiation direction of the laser beam so that the laser beam is irradiated from an angle inclined with respect to the arrangement direction of the solder bumps. A substrate carrying device for carrying the substrate on which the electronic component is placed;
The laser beam irradiation device is
A laser generator;
The solder melting apparatus according to claim 7, further comprising: a reflection unit that reflects the laser emitted from the laser generation unit toward the solder bump. The reflection part includes a prism,
The solder melting apparatus according to claim 8, wherein an acute angle of the prism is directed to the substrate side. A first imaging device for photographing a substrate on which the electronic component is placed;
The solder melting apparatus according to claim 7, further comprising an identification unit that identifies a position of the electronic component based on an image captured by the first imaging device. A second imaging device that images the irradiated position of the laser beam;
The solder melting apparatus according to claim 7, wherein the laser light irradiation device controls laser irradiation based on an image taken by the second imaging device.

Images