LED chip disposition method

Abstract

To provide an LED chip disposition method for efficiently disposing LED chips on a wiring board.SOLUTION: The LED chip disposition method comprises: an epitaxy substrate preparation step for preparing an epitaxy substrate 10 on which a plurality of LED chips 11 are arranged on a surface 10a via a buffer layer BF; a wiring board preparation step for preparing a wiring board 20 on which a plurality of wiring frames 21 larger than the LED chips 11 are disposed on a surface 20a; a positioning step for placing the surface 20a of the wiring board 20 and the surface 10a of the epitaxy substrate 10 face to face, positioning the LED chips 11 corresponding to the wiring frame 21, and crimping these in place via an anisotropic conductive paste 60; and a transfer step for irradiating the LED chips 11 with a laser beam LB to destruct the buffer layer BF and transferring the LED chips 11 from the epitaxy substrate 10 to the wiring frame 21. The positioning step and the transfer step are carried out sequentially to transfer the LED chips from the epitaxy substrate 10 and disposed these on the wiring board 20.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to a method for disposing an LED chip on a wiring board.

Background Art

[0002] A wafer on which a plurality of devices such as ICs, LSIs, and LEDs are partitioned by a dicing line and formed on the surface is diced into individual device chips by a dicing device and used in electrical devices such as mobile phones and personal computers.

[0003] In addition, a technique for improving functions by laminating device chips has also been proposed (see, for example, Patent Document 1). According to this technique, a plurality of device chips, for example, LED chips, are disposed on a temporary substrate via a foaming adhesive layer, the LED chip side of the temporary substrate is positioned facing the wiring board, and light of a specific wavelength is irradiated onto the foaming adhesive layer to generate bubbles, thereby enhancing peelability and peeling off, and it is possible to transfer the LED chip to the wiring board.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, when disposing an LED chip on a wiring board using the above-described conventional technique, the process of disposing the LED chip on a temporary substrate via a foaming adhesive layer once is included, and there is a problem of poor productivity.

[0006] The present invention has been made in view of the above facts, and its main technical problem is to provide an LED chip arranging method for efficiently arranging an LED chip on a wiring board without performing a step of arranging the LED chip on a temporary substrate via a foaming adhesive layer when arranging the LED chip on the wiring board.

Means for Solving the Problems

[0007] In order to solve the above main technical problem, according to the present invention, there is provided an LED chip arranging method for arranging an LED chip on a wiring board, including an epitaxial substrate preparation step of preparing an epitaxial substrate on which a plurality of LED chips are laminated on a surface via a buffer layer, a wiring board preparation step of preparing a wiring board on which a plurality of wiring frames larger than the LED chips are arranged on a surface, an alignment step of facing the surface of the epitaxial substrate to the surface of the wiring board, positioning the LED chips corresponding to the wiring frames, and pressing them with anisotropic conductive paste interposed therebetween, and a transfer step of irradiating a laser beam from the back side of the epitaxial substrate to the LED chips positioned corresponding to the wiring frames to destroy the buffer layer and transfer the LED chips from the epitaxial substrate to the wiring frames. Sequentially, an LED chip arranging method is provided in which the alignment step and the transfer step are performed to transfer and arrange the LED chips from the epitaxial substrate to the wiring board.

[0008] Preferably, an LED chip inspection step of inspecting the quality information obtained by inspecting the good and defective products of the LED chips laminated on the epitaxial substrate and recording the quality information is included, and the alignment step and the transfer step are performed only on the good LED chips based on the quality information. Further, preferably, an elimination step of irradiating a laser beam from the back side of the epitaxial substrate to the defective LED chips to destroy the buffer layer and preliminarily eliminating the defective LED chips from the epitaxial substrate is included before the alignment step.

[0009] After the transfer process, a heating process for solidifying the anisotropic conductive paste may be included. Further, in the transfer process, by transferring the LED chip laminated on the epitaxial substrate to the wiring frame of the wiring substrate, the dropout portion generated on the epitaxial substrate serves as a escape space for the LED chip already transferred to the wiring substrate, and the LED chip corresponding to the wiring frame may be positioned in the positioning process. Before the positioning process, a buffer layer may be destroyed by irradiating a defective LED chip with a laser beam from the back side of the epitaxial substrate, and the defective LED chip may be removed from the epitaxial substrate to form a dropout portion in advance on the epitaxial substrate, and the LED chip corresponding to the wiring frame may be positioned in the positioning process so that the dropout portion serves as a escape space for the LED chip already transferred to the wiring substrate.

Effect of the Invention

[0010] The method for disposing an LED chip according to the present invention includes an epitaxial substrate preparation step of preparing an epitaxial substrate on which a plurality of LED chips are laminated on the surface via a buffer layer, a wiring substrate preparation step of preparing a wiring substrate on which a plurality of wiring frames larger than the LED chips are disposed on the surface, a positioning step of facing the surface of the epitaxial substrate to the surface of the wiring substrate, positioning the LED chip corresponding to the wiring frame, and pressing with an anisotropic conductive paste interposed therebetween, and a transfer step of irradiating a laser beam from the back side of the epitaxial substrate to the LED chip positioned corresponding to the wiring frame to destroy the buffer layer and transferring the LED chip from the epitaxial substrate to the wiring frame. Sequentially, by performing the positioning step and the transfer step, the LED chip is transferred and disposed from the epitaxial substrate to the wiring substrate. Thus, unlike the prior art, the step of disposing the LED chip on the temporary substrate via the foaming adhesive layer is unnecessary, and the productivity is improved. Further, by destroying the buffer layer corresponding to an arbitrary LED chip from the back side of the epitaxial substrate, the arbitrary LED chip can be transferred to the wiring substrate.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0012] Hereinafter, embodiments of an LED chip arrangement method configured based on the present invention will be described in detail with reference to the accompanying drawings.

[0013] (Epitaxial Substrate Preparation Step, Wiring Substrate Preparation Step) When implementing the method for arranging LED chips according to this embodiment, first, an epitaxial substrate preparation step and a wiring substrate preparation step described below are carried out. The order of carrying out the epitaxial substrate preparation step and the wiring substrate preparation step is not particularly limited, and any of the steps may be carried out before the positioning step described later.

[0014] The epitaxial substrate preparation step is a step of preparing an epitaxial substrate on which a plurality of LED chips are laminated on the surface via a buffer layer. FIG. 1(a) shows the epitaxial substrate 10 prepared in the epitaxial substrate preparation step of this embodiment. FIG. 1(b) shows a cross-sectional view taken along line A-A of FIG. 1(a). As shown in the figure, the epitaxial substrate 10 has a substantially disc shape, and is, for example, configured with a diameter of 4 inches (≈100 mm). The epitaxial substrate 10 is formed, for example, by laminating an LED chip 11, which is a light-emitting device, on a buffer layer BF made of a Ga compound (for example, gallium nitride: GaN) on the upper surface of a sapphire substrate to form a surface 10a. The emission color of the LED chip 11 is, for example, any one of red, green, and blue. The LED chip 11 is, for example, an LED formed with dimensions of 10 μm×10 μm in plan view, and electrodes (not shown) for supplying power to cause the LED chip 11 to emit light are formed on the surface.

[0015] As shown in the figure, a linear portion indicating the crystal orientation, a so-called orientation flat OF, is formed on the outer periphery of the epitaxial substrate 10, and the LED chips 11 formed on the surface 10a of the epitaxial substrate 10 are arranged in a direction along the orientation flat OF and in a direction perpendicular thereto.

[0016] FIG. 2(a) shows a wiring board 20 prepared by the wiring board preparation step of the present embodiment. The wiring board 20 has a substantially disc shape. The wiring board 20 is formed with substantially the same dimensions as the above-described epitaxial substrate 10, that is, a diameter of 4 inches (≈100 mm). The wiring board 20 is, for example, a substrate formed of silicon (Si). As can be understood from FIG. 2(b) showing the B-B cross section of FIG. 2(a) in addition to FIG. 2(a), it is a substrate in which wiring frames 21 having a rectangular shape in plan view are formed in each region of the surface 20a partitioned by the division planned line 22. The wiring frame 21 has a disposition area on the surface 21a where the LED chip 11 is disposed. At the bottom of each disposition area, when the above-described LED chip 11 is disposed, two bumps are formed which are electrically connected to the electrodes (not shown) of the LED chip 11 (the illustration is omitted). In the following description, the case where there is one disposition area formed in the disposition frame 21 will be described, but a plurality (for example, three) may be provided. The wiring frame 21 is formed with dimensions larger than those of the LED chip 11, and is formed, for example, as a rectangle of 80 μm × 40 μm in plan view.

[0017] On the surface 21a of the above-described wiring frame 21, at a position adjacent to the wiring area, electrodes (not shown) that are conductive with the bumps disposed on the wiring frame 21 are provided, and power is supplied from the electrodes to the LED chip 11 disposed in the wiring area via the bumps. The wiring frame 21 described on the wiring board 20 in FIG. 2 is shown larger than the actual dimensions for convenience of explanation. Actually, it is much smaller than that shown, and more wiring frames 21 are formed on the surface 20a of the wiring board 20.

[0018] In the method for disposing LED chips according to this embodiment, after the wiring board preparation step, in preparation for performing the positioning step and the transfer step described later, as shown in FIG. 3, a frame support step is performed in which the wiring board 20 is supported by an annular frame F via an adhesive tape T. As shown in the figure, an opening Fa capable of accommodating the above wiring board 20 is formed in the annular frame F. The frame support step positions the surface 20a of the wiring board 20 upward and at the center of the opening Fa, and integrates the back surface 20b of the wiring board 20 and the frame F by adhering them with an adhesive tape T having an adhesive layer on the surface.

[0019] (Positioning step) After performing the epitaxial substrate preparation step and the wiring board preparation step, using the laser processing apparatus 40 shown in FIG. 4, the surface 10a of the epitaxial substrate 10 is faced to the surface 20a of the wiring board 20, and the LED chip 11 corresponding to the above wiring frame 21 is positioned. A positioning step of pressing with an anisotropic conductive paste 60 to be described below interposed therebetween, and a transfer step of irradiating a laser beam to the LED chip 11 positioned corresponding to the wiring frame 21 from the back surface 10b side of the epitaxial substrate 10 to break the buffer layer BF and transferring the LED chip 11 from the epitaxial substrate 10 to the wiring frame 21 are performed.

[0020] With reference to FIG. 4, the laser processing apparatus 40 used in the present embodiment will be described. The illustrated laser processing apparatus 40 includes a base 41, holding means 42 for holding the wiring board 20, moving means 43 for moving the holding means 42, laser beam irradiation means 44 for irradiating a laser beam, a vertical wall 45a extending upward from the upper surface of the base 41, and a horizontal portion 45b extending substantially horizontally from the upper end of the vertical wall 45a and housing the optical system of the laser beam irradiation means 44, and a control means (not shown) constituted by a computer. Each operating part of the laser processing apparatus 40 is controlled by the control means. Further, on the lower surface of the tip of the horizontal portion 45b of the frame 45, a condenser 44a including an fθ lens constituting the laser beam irradiation means 44, an epitaxial substrate holding means 50 disposed directly below the condenser 44a, and an imaging means 48 for imaging the wiring board 20 held on the chuck table 42e at a position adjacent to the condenser 44a in the X direction indicated by the arrow X in the figure are disposed.

[0021] The holding means 42 includes a rectangular X-direction movable plate 42a mounted on the base 41 so as to be movable in the X direction, a rectangular Y-direction movable plate 42b mounted on the X-direction movable plate 42a so as to be movable in the Y direction orthogonal to the X direction, a cylindrical support column 42c fixed to the upper surface of the Y-direction movable plate 42b, a rectangular cover plate 42d fixed to the upper end of the support column 42c, and a chuck table 42e extending upward through a long hole formed in the cover plate 42d. On the outer periphery of the chuck table 42e, four clamps 42f for gripping a frame F supporting the wiring board 20 held on the chuck table are arranged at equal intervals. Note that the plane defined by the above-described X direction and Y direction is substantially horizontal.

[0022] The moving means 43 includes an X-direction moving means 43a, a Y-direction moving means 43b, and a rotation driving means (not shown). The X-direction moving means 43a includes a motor 431 and a ball screw 432 rotated by the motor 431. It converts the rotational motion of the motor 431 into a linear motion and transmits it to the X-direction movable plate 42a, and advances and retreats the X-direction movable plate 42a in the X direction along a pair of guide rails 41a, 41a arranged along the X direction on the base 41. The Y-direction moving means 43b includes a motor 433 and a ball screw 434. It converts the rotational motion of the motor 433 into a linear motion, transmits it to the Y-direction movable plate 42b, and advances and retreats the Y-direction movable plate 42b in the Y direction along the guide rail on the X-direction movable plate 42b. Further, the chuck table 42e can be rotated by a rotation driving means (not shown). Note that position detection means (not shown) are respectively arranged in the X-direction moving means 43a, the Y-direction moving means 43b, and the rotation driving means. The position in the X direction, the position in the Y direction, and the rotational position in the circumferential direction of the chuck table 42e are accurately detected, and the X-direction moving means 43a, the Y-direction moving means 43b, and the rotation driving means are driven based on a signal instructed by the control means described later, so that the chuck table 42e can be accurately positioned at an arbitrary position and angle.

[0023] The imaging means 48 includes an optical system constituting a microscope and an imaging element (CCD), and is configured to send the captured image signal to the control means for recording and to display it on a display means (not shown). The control means is constituted by a computer and includes a central processing unit (CPU) that performs arithmetic processing according to a control program, a read-only memory (ROM) that stores the control program and the like, a readable and writable random access memory (RAM) for temporarily storing the detected detection values, arithmetic results, etc., an input interface, and an output interface (illustrations of details are omitted).

[0024] The epitaxial substrate holding means 50 will be described in detail with reference to FIG. 5. As shown in FIG. 5(a), the epitaxial substrate holding means 50 includes a substrate holding ring 52 and a holding arm 54 for supporting the substrate holding ring 52. The holding arm 54 is connected via an opening hole 56a to drive means (not shown) built into a holding base 56 disposed on the lower surface of the tip of the horizontal portion 45b of the above-described frame body 45. The substrate holding ring 52 has an annular opening 58 formed in accordance with the dimensions of the above-described epitaxial substrate 10. Inside, an annular stepped portion 52a on which the epitaxial substrate 10 is placed is disposed along the inside of the substrate holding ring 52. A plurality of suction holes 52b for sucking and holding the placed epitaxial substrate 10 are arranged at predetermined intervals in the circumferential direction on the upper surface of the stepped portion 52a. When holding the epitaxial substrate 10, for example, as shown in FIG. 5(b), the orientation flat OF of the epitaxial substrate 10 is positioned along a straight portion 52c formed in the substrate holding ring 52, and the surface 10a of the epitaxial substrate 10 is placed upward on the stepped portion 52a forming the opening 58. The suction holes 52b are connected to suction means (not shown) via suction passages formed inside the substrate holding ring 52 and the holding arm 54. By operating the suction means, the epitaxial substrate 10 can be sucked and held on the stepped portion 52a of the substrate holding ring 52.

[0025] The holding arm 54 can be rotated in the direction indicated by arrow R1 in FIG. 5(c) by the drive means disposed in the holding base 56, and the substrate holding ring 52 can be rotated by rotating the holding arm 54. Thereby, the surface 10a side of the epitaxial substrate 10 sucked and held by the substrate holding ring 52 can be directed downward, and the back surface 10b can be exposed upward through the opening 58 of the substrate holding ring 52. Further, in accordance with a command from the above-described control means, the drive means is operated so that the holding arm 54 can be moved in the vertical direction indicated by arrow R2 along the opening hole 56a of the holding base 56, and the substrate holding ring 52 can be controlled to a desired height position.

[0026] In addition to the condenser 44a described above, the laser beam irradiation means 44 includes, for example, a laser beam oscillator, a reflection mirror that converts the direction of the laser beam oscillated from the laser beam oscillator, and an optical system such as a galvanometer mirror that adjusts the irradiation direction of the laser beam reflected by the reflection mirror toward a predetermined position of the fθ lens of the condenser 44a (all are not shown in the drawings). By appropriately controlling the direction of the galvanometer mirror, the laser beam LB can be irradiated to a desired position of the epitaxial substrate 10 held by the substrate holding ring 52 positioned directly below the condenser 44a.

[0027] The laser processing apparatus 40 has a configuration generally as described above. In addition to FIGS. 4 and 5, the positioning process using the above-described laser processing apparatus 40 will be described with reference to FIG. 6.

[0028] First, the chuck table 42e in the laser processing apparatus 40 shown in FIG. 4 is moved to the loading / unloading position on the front side in the figure by the operation of the moving means 43, and the surface 20a of the wiring board 20 supported by the frame F via the adhesive tape T is placed upward on the upper surface (holding surface) of the chuck table 42e. Next, the suction means for generating negative pressure on the holding surface of the chuck table 42e (not shown) is operated, and the frame F is gripped by the clamp 42f to suck and hold the wiring board 20. Once the wiring board 20 is sucked and held by the chuck table 42e, the above-described moving means 43 is operated to move the wiring board 20 directly below the imaging means 48. Then, the surface 20a of the wiring board 20 is imaged by the imaging means 48, and alignment for detecting the position and orientation of a predetermined wiring frame 21 disposed on the surface 20a of the wiring board 20 is executed. By this alignment, the longitudinal direction of the wiring frame 21 is positioned along the X direction, and the substrate holding ring 52 is lowered to a predetermined position according to the command of the above-described control means, so that the epitaxial substrate holding means 50 is in the state shown in FIG. 5(a), and the surface 10a of the epitaxial substrate 10 prepared in the epitaxial substrate preparation step is placed upward on the stepped portion 52a of the substrate holding ring 52. As described above, when placing the epitaxial substrate 10 on the substrate holding ring 52, the epitaxial substrate 10 can be accurately positioned in a desired direction with respect to the substrate holding ring 52 by positioning and placing the orientation flat OF of the epitaxial substrate 10 along the straight portion 52c of the substrate holding ring 52 (see FIG. 5(b)).

[0029] If the epitaxial substrate 10 is placed on the stepped portion 52a, the suction means (not shown) is operated to suck through the suction holes 52b of the stepped portion 52a as shown in FIG. 5(b) and suck and hold the epitaxial substrate 10. Next, the driving means of the holding base 56 is operated to rotate the holding arm 54 of the substrate holding ring 52 by 180° in the direction of arrow R1 in FIG. 5(c), expose the back surface 10b side of the epitaxial substrate 10 upward through the opening 58 of the substrate holding ring 52, and direct the surface 10a side on which the LED chip 11 is laminated downward. If the epitaxial substrate 10 is rotated in this way, based on the position information of a predetermined wiring frame 21 of the wiring substrate 20 obtained by performing the alignment, the moving means 43 is operated to move the wiring substrate 20 in the X direction. As shown in FIG. 6(a), the surface 10a side of the epitaxial substrate 10 is faced to the surface 20a of the wiring substrate 20, and the LED chip 11 corresponding to the predetermined wiring frame 21 (the leftmost wiring frame 21 in the illustrated example) is positioned.

[0030] Here, as shown in FIG. 6(a), in a predetermined wiring frame 21 of the wiring substrate 20, an anisotropic conductive paste 60 is applied to the disposed area where the LED chip 11 positioned corresponding to the wiring frame 21 is pressure-bonded. As the anisotropic conductive paste 60, a well-known anisotropic conductive paste can be adopted. For example, it is a material in which solder particles are dispersed in a thermoplastic resin and solidifies by heating to form a metal bond between the electrodes of the LED chip 11 and the bumps of the wiring frame 21. Note that the anisotropic conductive paste 60 is not limited to being applied to the wiring frame 21 side and may be applied to the LED chip 11 side to be transferred. The timing of applying this anisotropic conductive paste 60 is arbitrary, but it is preferable to apply it to either the wiring frame 21 or the LED chip 11 pressure-bonded to the wiring frame 21 every time a predetermined LED chip 11 is pressure-bonded to a predetermined wiring frame 21.

[0031] As described above, when the surface 10a of the epitaxial substrate 10 is faced to the surface 20a of the wiring substrate 20 and the LED chip 11 corresponding to the predetermined wiring frame 21 coated with the anisotropic conductive paste 60 is positioned, as shown in FIG. 6(b), the substrate holding ring 52 is lowered in the direction indicated by the arrow R3 to bring the epitaxial substrate 10 close to the wiring substrate 20, so that the predetermined LED chip 11 is brought close to the wiring area coated with the anisotropic conductive paste 60 in the wiring frame 21 of the wiring substrate 20, and the LED chip 11 is crimped to the wiring frame 21 with the anisotropic conductive paste 60 interposed therebetween. At this time, strong crimping is not necessary, and it is only necessary that the anisotropic conductive paste 60 is surely interposed between the LED chip 11 and the wiring frame 21 of the wiring substrate 20. This is the positioning step of the present embodiment.

[0032] As described above, if the positioning step is performed, the laser beam irradiation means 44 is operated to perform the transfer step of transferring the LED chip 11 from the epitaxial substrate 10 to the wiring frame 21. More specifically, the positions of the laser oscillator and the galvano mirror of the laser beam irradiation means 44 are controlled according to the command from the control means to adjust the incident position with respect to the fθ lens accommodated in the condenser 44a. As shown in FIG. 7(a), from the back surface 10b side of the epitaxial substrate 10, the condensing point of the laser beam LB having a wavelength (for example, 266 nm) that is transmissive to the epitaxial substrate 10 and absorptive to the buffer layer BF is positioned corresponding to the target LED chip 11 and irradiated at the position of the buffer layer BF located on the back surface of the LED chip 11. As a result, the buffer layer BF is destroyed, a gas layer is formed at the interface between the epitaxial substrate 10 and the LED chip 11, the LED chip 11 is peeled off from the epitaxial substrate 11, and is transferred to the wiring frame 21 side. At this time, the spot diameter at the condensing point of the laser beam LB positioned at the buffer layer BF is set so that the entire buffer layer BF in the region (10 μm × 10 μm) where the LED chip 11 to be transferred is formed is destroyed.

[0033] In addition, the processing conditions of the laser processing performed in the above-described relocation process are set as follows, for example. Wavelength: 266 nm Repetition frequency: 200 kHz Average output: 0.2 W Spot diameter: φ15 μm

[0034] As described above, if the first LED chip 11 is relocated to a predetermined wiring frame 21, the holding base 56 is operated to raise the substrate holding ring 52 once, and the moving means 43 is operated to move the wiring substrate 20 in the X direction indicated by the arrow X in FIG. 7(a). Then, as shown in FIG. 7(b), the wiring frame 21 of the wiring substrate 20 to which the next LED chip 11 is to be relocated is positioned directly below the LED chip 11 formed adjacent to the first LED chip 11 relocated to the wiring substrate 20 in the X direction. At this time, similar to the relocation of the first LED chip 11 described above, the anisotropic conductive paste 60 is applied to the area where the wiring frame 21 is disposed, and the same procedure as the above-described positioning process is performed. With the anisotropic conductive paste 60 interposed therebetween, the LED chip 11 is crimped to the area where the wiring frame 21 is disposed. Then, based on the processing conditions and procedures of the laser processing similar to the above-described relocation process, the relocation process is performed. As shown in FIG. 7(b), from the back surface 10b side of the epitaxial substrate 10, the condensing point of the laser beam LB having a wavelength that is transmissive to the epitaxial substrate 10 and absorptive to the buffer layer BF is positioned on the buffer layer BF located on the back surface of the target LED chip 11 and irradiated. As a result, the buffer layer BF is destroyed, a gas layer is formed at the interface between the epitaxial substrate 10 and the LED chip 11, and the LED chip 11 is peeled off from the epitaxial substrate 11 and relocated to the wiring frame 21.

[0035] By further performing the above-described positioning step, as shown in FIG. 7(c), an anisotropic conductive paste 60 is interposed between the wiring frame 21 of the wiring substrate 20 and the LED chip 11, and the LED chip 11 formed on the epitaxial substrate 10 is pressure-bonded to the wiring frame 21 of the wiring substrate 20. Then, by performing the same procedure as the above-described transfer step, from the back surface 10b side of the epitaxial substrate 10, the condensing point of the laser beam LB having a wavelength that is transmissive to the epitaxial substrate 10 and absorptive to the buffer layer BF is positioned on the buffer layer BF located on the back surface of the target LED chip 11 and irradiated. As a result, the buffer layer BF is destroyed, a gas layer is formed at the interface between the epitaxial substrate 10 and the LED chip 11, and the target LED chip 11 is peeled off from the epitaxial substrate 11 and transferred to the wiring frame 21 side.

[0036] By further performing the same procedure as the above-described positioning step and transfer step, as shown in FIG. 7(d), it is possible to transfer the LED chip 11 to the wiring frame 21 of the wiring substrate 20 adjacent in the X direction. By repeating the above-described positioning step and transfer step, in the wiring substrate 20, the LED chip 11 can be transferred to all the wiring frames 21 positioned along the X direction. Here, according to the above-described procedure, when the LED chip 11 formed in the X direction on the epitaxial substrate 10 sucked and held by the substrate holding ring 52 is transferred to the wiring frame 21, a dropout portion P from which the LED chip 11 is removed is formed on the epitaxial substrate 10 side. By sequentially transferring the LED chips 11 arranged in the X direction to a plurality of wiring frames 21 positioned along the X direction as in the above-described procedure, as shown in FIG. 7(d), since the dropout portion P functions as a clearance for the LED chips 11 already transferred to the wiring substrate 20 side, the LED chips 11 can be efficiently transferred to the wiring frames 21.

[0037] As described above, if the positioning process and the transfer process are carried out and the LED chips 11 are transferred to all the wiring frames 21 arranged in the X direction, the wiring substrate 20 is fed in the Y direction by an amount corresponding to the interval at which the wiring frames 21 are arranged, and the columns of the wiring frames 21 that are adjacent in the Y direction to the wiring frames 21 to which the LED chips 11 have been transferred and to which the LED chips 11 have not yet been transferred are positioned with the LED chips 11 on the epitaxial substrate 10. Then, the same procedure as the above-described positioning process and transfer process is carried out to transfer the LED chips 11 to the wiring frames 21. By repeatedly carrying out the above-described positioning process, transfer process, and indexing feed, the LED chips 11 can be transferred to all the wiring frames 21 arranged on the wiring substrate 20, and the method for arranging LED chips according to the present embodiment is completed.

[0038] According to the method for arranging LED chips of the present embodiment described above, the step of arranging the LED chips on the temporary substrate via the foaming adhesive layer as in the prior art becomes unnecessary, and the productivity is improved. Further, by destroying the buffer layer BF corresponding to an arbitrary LED chip 11 from the back surface 10b of the epitaxial substrate 10, the arbitrary LED chip 11 can be transferred to the wiring substrate 20.

[0039] (Heating process) After carrying out the above-described transfer process and transferring the LED chips 11 to all the wiring frames 21 of the wiring substrate 20, it is preferable to carry out a heating process of heating the anisotropic conductive paste 60. The heating process is a process for more surely solidifying the anisotropic conductive paste 60 after the transfer process. For example, a heating heater is embedded in the chuck table 42e that holds the wiring substrate 20 to heat the wiring substrate 20. Thereby, the solidification of the anisotropic conductive paste 60 is promoted, and the electrodes of the LED chips 11 and the bumps of the wiring frames 21 are surely metallically bonded. Note that if the anisotropic conductive paste 60 is sufficiently heated by laser processing being performed on the buffer layer BF in the above-described transfer process, the heating process may be omitted.

[0040] (LED chip inspection process) In the present invention, before performing the above-described transfer process, an LED chip inspection process may be included in which the LED chips 11 laminated on the epitaxial substrate 10 are inspected and quality information is recorded. In the LED chip inspection process, power is supplied to the electrodes of the LED chips 11 laminated on the buffer layer BF on the surface 10a of the epitaxial substrate 10, and it is inspected whether the LED chips 11 operate normally, that is, whether they are non-defective or defective. The quality information including the position information of the defective LED chips 11 in the epitaxial substrate 10 obtained by this inspection is transmitted to and recorded by the control means of the laser processing apparatus 40.

[0041] As described above, when the LED chip inspection process is performed and the non-defective and defective products of the LED chips 11 laminated on the epitaxial substrate 10 are distinguished, the above-described positioning process and transfer process are performed only on the LED chips 11 determined to be non-defective. Thereby, it is avoided that the defective LED chips 11 are transferred to the wiring frame 21 of the wiring substrate 20.

[0042] (Exclusion process) Furthermore, before performing the above-described transfer process, if the above-described LED chip inspection process has been performed and the good LED chips 11 and the defective LED chips 11 have been distinguished, it is preferable to perform the exclusion process described below before performing the transfer process. In this exclusion process, the epitaxial substrate 10 is held against the substrate holding ring 52 of the epitaxial substrate holding means 50, and as shown in FIG. 5(c), the back surface 10b of the epitaxial substrate 10 is oriented upward. Then, based on the position information of the defective LED chips 11 obtained by the above-described LED chip inspection process, the laser beam irradiation means 44 is operated, and from the back surface 10b side of the epitaxial substrate 10, the condensing point of the above-described laser beam LB is positioned on the buffer layer BF on which the LED chips 11 determined to be defective are stacked and irradiated. The processing conditions for the laser processing at this time may be the same as the processing conditions for the laser processing in the above-described transfer process. Thereby, the buffer layer BF on which the defective LED chips 11 are stacked is destroyed, and before the transfer process is performed, the defective LED chips 11 are preliminarily excluded from the epitaxial substrate 10, and an exclusion process for forming a dropped portion from which the LED chips 11 have been removed on the epitaxial substrate 10 is completed.

[0043] By performing the above-described exclusion process, defective LED chips 11 that should not be transferred to the wiring frame 21 of the wiring substrate 20 are preliminarily excluded, so that it is avoided that they are erroneously transferred to the wiring frame 21 of the wiring substrate 20, and in the transfer process, it is possible to avoid a collision between the LED chips 11 already disposed on the wiring substrate 20 and the LED chips 11 remaining on the epitaxial substrate 10 as defective products.

Description of Reference Numerals

[0044] 10: Epitaxial substrate 10a: Front surface 10b: Back surface 11: LED chip 20: Wiring substrate 20a: Front surface 20b: Back surface 21: Wiring frame 21a: Front surface 22: Scheduled cutting line 40: Laser processing device 41: Base 42: Holding means 42a: X-direction movable plate 42b: Y-direction movable plate 42c: Support pillar 42d: Cover plate 42e: Chuck table 43: Moving means 43a: X-direction moving means 431: Motor 432: Ball screw 43b: Y-direction moving means 433: Motor 434: Ball screw 44: Laser beam irradiation means 44a: Condenser 50: Epitaxial substrate holding means 52: Substrate holding ring 52a: Step portion 52b: Suction hole 52c: Straight portion 54: Holding arm 56: Holding base 56a: Opening hole 58: Opening F: Frame Fa: Opening BF: Buffer layer OF: Orientation flat

Claims

1. An LED chip arranging method for arranging LED chips on a wiring board, comprising: an epitaxial substrate preparation step of preparing an epitaxial substrate on which a plurality of LED chips are laminated on a surface via a buffer layer; a wiring board preparation step of preparing a wiring board on which a plurality of wiring frames larger than the LED chips are arranged on a surface; an alignment step of facing the surface of the epitaxial substrate to the surface of the wiring board, positioning an LED chip corresponding to the wiring frame, and pressing with an anisotropic conductive paste interposed therebetween; a transfer step of irradiating a laser beam from the back side of the epitaxial substrate to the LED chip positioned corresponding to the wiring frame to destroy the buffer layer and transfer the LED chip from the epitaxial substrate to the wiring frame; an LED chip arranging method of sequentially performing the alignment step and the transfer step to transfer and arrange the LED chips from the epitaxial substrate to the wiring board.

2. including an LED chip inspection step of inspecting the quality information obtained by inspecting the good and defective products of the LED chips laminated on the epitaxial substrate and recording the quality information; The LED chip arranging method according to claim 1, wherein the alignment step and the transfer step are performed only on the good LED chips based on the quality information.

3. The LED chip arranging method according to claim 2, including an elimination step of irradiating a laser beam from the back side of the epitaxial substrate to the defective LED chips to destroy the buffer layer and preliminarily eliminating the defective LED chips from the epitaxial substrate before the alignment step.

4. The LED chip arranging method according to claim 1, including a heating step of solidifying the anisotropic conductive paste after the transfer step.

5. In the transfer step, when transferring the LED chips laminated on the epitaxial substrate to the wiring frames of the wiring board, the LED chips corresponding to the wiring frames are positioned in the alignment step so that the dropout portions generated on the epitaxial substrate serve as escape spaces for the LED chips already transferred to the wiring board. The LED chip arranging method according to claim 1.

6. Before the positioning step, a laser beam is irradiated from the back side of the epitaxial substrate onto the defective LED chip to destroy the buffer layer, the defective LED chip is removed from the epitaxial substrate to form a pre-dropped portion on the epitaxial substrate, and in the positioning step, the LED chip corresponding to the wiring frame is positioned so that the dropped portion serves as a escape space for the LED chip already transferred to the wiring substrate. The method for arranging an LED chip according to claim 2.

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