JP2022054148A - Electronic component mounting method and manufacturing method for micro-led display - Google Patents

Abstract

To improve the yield when mounting an electronic component.SOLUTION: An electronic component mounting method for mounting an electronic component on a substrate having a circuit mounted thereon includes the steps of: attaching a first transfer member 3 whose adhesion force decreases by irradiation with UV ray to a light-transmitting substrate 2 where a plurality of electronic components 1 are formed in accordance with a predetermined arrangement on one surface; transferring the electronic components 1 to one surface of the first transfer member 3 by laser lift-off for separating the electronic components 1 from the light-transmitting substrate 2; after performing processing for preventing exposure to oxygen on the first transfer member 3, to which the electronic components 1 have been transferred, irradiating the first transfer member 3 with UV rays so as to decrease the adhesive force of the first transfer member 3; by the use of a second transfer member 5 whose adhesive force is higher than that of the first transfer member 3 with the decreased adhesive force, transferring the electronic components 1 from the first transfer member 3 to the second transfer member 5 by using a difference in adhesive force; and mounting the electronic components 1 from the second transfer member 5 to a substrate 6.SELECTED DRAWING: Figure 1

Description

The present invention relates to a technique for mounting an electronic component such as a micro LED (Light Emitting Diode), and in particular, an electronic component mounting method capable of improving the yield at the time of mounting the electronic component and a micro LED display adopting this method. It is related to the manufacturing method.

Conventionally, a mounting method for mounting a semiconductor chip made of micro LEDs on a circuit board has been proposed (see, for example, Patent Document 1). According to the mounting method of Patent Document 1, the first transfer step, the adhesive force reducing step, the second transfer step, and the mounting step are sequentially executed.

Specifically, in the first transfer step, first, a carrier substrate having a plurality of semiconductor chips and a first pressure-sensitive adhesive sheet are prepared. Then, in the first transfer step, the semiconductor chip is irradiated with laser light to peel off the semiconductor chip from the carrier substrate, and the semiconductor chip is transferred to the first pressure-sensitive adhesive sheet.

Next, in the adhesive force reducing step, the adhesive force of the first adhesive sheet is reduced by heating the semiconductor chip and the first adhesive sheet. Further, in the second transfer step, the semiconductor chip is peeled off from the first pressure-sensitive adhesive sheet by transmitting the first pressure-sensitive adhesive sheet and irradiating one surface of the semiconductor chip with a laser beam to peel off the semiconductor chip from the first pressure-sensitive adhesive sheet. Transfer to. Then, in the mounting step, the semiconductor chip transferred to the second adhesive sheet is thermocompression bonded to the circuit board to mount the semiconductor chip on the circuit board.

Here, in the above-mentioned adhesive force reducing step, in detail, a method of reducing the adhesive force of the adhesive film by heating the adhesive film of the first adhesive sheet to a predetermined temperature is adopted. In Patent Document 1, when an adhesive film whose adhesive force changes by irradiation with UV (Ultra Violet) light is used, a method of reducing the adhesive force by irradiating the adhesive film with UV light. It is stated that may be carried out.

Japanese Unexamined Patent Publication No. 2019-114660

However, Patent Document 1 does not disclose specific contents other than the above when an adhesive film whose adhesive strength changes by irradiation with UV light (ultraviolet rays) is used. On the other hand, when we independently conducted an experiment on the transfer of micro LEDs as an electronic component using a transfer member whose adhesive strength is reduced by UV irradiation (for example, tape for UV peeling), the micro LEDs are not transferred normally. Turned out to be possible.

Therefore, the present invention addresses such a problem, and in the case of adopting a transfer member whose adhesive strength is reduced by irradiation with ultraviolet rays, an electronic component mounting method capable of improving the yield at the time of mounting the electronic component and the method thereof. It is an object of the present invention to provide a method of manufacturing a micro LED display to which an electronic component mounting method is applied.

In order to achieve the above object, the first invention is an electronic component mounting method for mounting an electronic component on a substrate on which a circuit is mounted, and a plurality of electronic components are formed on one surface according to a predetermined arrangement. One of the first transfer members by the step of attaching the first transfer member whose adhesive strength is reduced by irradiation with ultraviolet rays to the light transmissive substrate and the laser lift-off for peeling the electronic components from the light transmissive substrate. After the step of transferring the electronic component to the surface and the treatment of preventing the exposure to oxygen to the first transfer member to which the electronic component is transferred, the first transfer member is irradiated with ultraviolet rays. Then, the difference in the adhesive force between the step of reducing the adhesive force of the first transfer member and the second transfer member having a stronger adhesive force than the first transfer member having the reduced adhesive force is used. The present invention includes a step of transferring the electronic component from the first transfer member to the second transfer member, and a step of mounting the electronic component from the second transfer member on the substrate.

In order to achieve the above object, the second invention is a method for manufacturing a micro LED display capable of full-color display, in which a plurality of micro LEDs are formed according to a predetermined arrangement on one surface. By the step of attaching the first transfer member whose adhesive strength is reduced by irradiation with ultraviolet rays to the sex substrate and the laser lift-off for peeling the micro LED from the light transmissive substrate, the transfer member is attached to one surface of the first transfer member. After the step of transferring the micro LED and the treatment of preventing the exposure to oxygen to the first transfer member to which the micro LED is transferred, the first transfer member is irradiated with ultraviolet rays. The difference in the adhesive strength is utilized by using the step of reducing the adhesive strength of the first transfer member and the second transfer member having a stronger adhesive strength than the first transfer member having the reduced adhesive strength. The step of transferring the micro LED from the first transfer member to the second transfer member, the step of mounting the micro LED from the second transfer member on a substrate on which a circuit is mounted, and the micro LED. A step of forming a flat plate-shaped flattening film on a substrate on which the above-mentioned is mounted, and fluorescence having a plurality of phosphor cells whose arrangement is determined according to the arrangement of the microLEDs on the substrate on which the flattening film is formed. Includes a step of forming a body cell array.

According to the electronic component mounting method according to the first invention, in the step of reducing the adhesive force of the first transfer member, after the treatment for preventing exposure to oxygen is performed, the ultraviolet rays are applied to the first transfer member. Since the adhesive strength of the first transfer member is reduced by irradiation, the electronic component is not adversely affected by exposure to oxygen, and the electronic component is easily transferred to the first transfer member, and the electronic component is mounted. It is possible to improve the yield of time.

Further, according to the method for manufacturing a micro LED display according to the second invention, the electronic component mounting method according to the first invention is adopted. Therefore, when the micro LED is adopted as an electronic component, when the micro LED is mounted. It is possible to manufacture a micro LED display with improved yield.

It is a flow chart which shows the whole process of 1st Embodiment of the electronic component mounting method by this invention. It is explanatory drawing which shows the process of the first half of the 1st Embodiment of the electronic component mounting method by this invention. It is explanatory drawing which shows the latter half process of 1st Embodiment of the electronic component mounting method by this invention. It is explanatory drawing which shows the structure of the light transmissive substrate. It is a schematic cross-sectional view which shows the structure of the 1st transfer member. It is a schematic cross-sectional view which shows the structure of the 2nd transfer member. It is a schematic cross-sectional view which shows the structure of a substrate. It is a top view of the board after the electronic component is mounted. It is explanatory drawing which shows an example of the process which prevents the exposure to oxygen. It is explanatory drawing which shows the other example of the treatment which prevents the exposure to oxygen. It is explanatory drawing which shows the process of the 2nd transfer by the 2nd transfer member in 2nd Embodiment of the electronic component mounting method by this invention. It is explanatory drawing which shows the process of mounting an electronic component in 2nd Embodiment of the electronic component mounting method by this invention. It is a flow chart which shows the process of the manufacturing method of the micro LED display by this invention. It is explanatory drawing which shows the process of forming a flattening film. It is explanatory drawing which shows the process of forming a fluorescent substance cell array. It is a top view of a fluorescent substance cell array. It is explanatory drawing which shows the process of forming a micro LED display. It is a top view of the micro LED display.

[First Embodiment]
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a flow chart showing all the steps of the first embodiment of the electronic component mounting method according to the present invention. FIG. 2 is an explanatory diagram showing a process of the first half of the first embodiment of the electronic component mounting method according to the present invention. FIG. 3 is an explanatory diagram showing a process of the latter half of the first embodiment of the electronic component mounting method according to the present invention. The electronic component to be mounted on the substrate by the electronic component mounting method according to the present invention may be, for example, an electronic component formed on a wafer such as a sapphire substrate in a semiconductor process, and will be described below by taking the micro LED 1 as an example. .. The first half process and the second half process are separated for convenience of explanation, and are not limited thereto.

First, in the pasting of the first transfer member shown in FIG. 1 (step S1), as shown in FIG. 2A, a plurality of plurality of members are attached to one surface (hereinafter, simply referred to as “surface”) according to a predetermined arrangement. A process of attaching the first transfer member 3 whose adhesive strength is reduced by ultraviolet irradiation is executed on the light transmissive substrate 2 on which the micro LED 1 is formed. The light transmissive substrate 2 is a substrate that transmits laser light used for laser lift-off, which will be described later, and is, for example, a sapphire substrate. The first transfer member 3 is, for example, a tape for UV peeling.

FIG. 4 is an explanatory diagram showing the configuration of the light transmissive substrate 2. FIG. 4A is a plan view of the light transmissive substrate 2. However, the light transmissive substrate 2 (hereinafter, simply referred to as “substrate 2”) is a circular wafer obtained by dicing and a part thereof being taken out. FIG. 4B is an enlarged plan view of the micro LED 1. As shown in FIG. 4A, each micro LED 1 is formed in a matrix on the surface of the substrate 2 by a two-dimensional arrangement having a predetermined arrangement pitch. In FIG. 4A, as an example, each micro LED1 is formed in an array of 5 rows and 12 columns. In this case, for example, the spacing of the array pitches in the row direction is P1, and the spacing of the array pitches in the column direction is P2.

Further, as shown in FIG. 4B, the micro LED 1 includes a pair of electrode portions 1a and 1b (hereinafter, the electrode portions 1a and 1b may be collectively referred to as “electrode portion 10”) and an LED main body portion 1c. To prepare for. The pair of electrode portions 1a and 1b are, for example, electrode pads that enable energization from an external circuit to the micro LED 1, in which the electrode portion 1a is an n-side electrode pad (cathode electrode) and the electrode portion 1b is a p-side electrode pad (. Anode electrode).

In the micro LED 1, the LED main body 1c is manufactured using, for example, gallium nitride (GaN) as a main material. Specifically, the micro LED 1 may be an ultraviolet light emitting diode (UV-LED) or an LED that emits blue light. In the present embodiment, for example, in consideration of the conversion efficiency of the RGB phosphor used in the method for manufacturing a micro LED display described later, for example, an ultraviolet light emitting diode (UV-) that emits light corresponding to a peak wavelength of 385 nm. LED) may be selected. In FIG. 4, the micro LED 1 may be selected, for example, with an external size within a range of horizontal (15 to 20 μm) × vertical (30 to 45 μm). Further, the thickness of the micro LED 1 may be selected within the range of, for example, about 10 to 30 μm.

FIG. 5 is a schematic cross-sectional view showing the configuration of the first transfer member 3. The first transfer member 3 is provided in the order of the base film 31 and the pressure-sensitive adhesive layer 32 from the lower layer. Further, a removable protective film 4 that can be repeatedly attached is attached to the upper layer of the first transfer member 3. As the first transfer member 3 and the protective film 4, for example, ELP UB-3103AC (manufactured by Nitto Denko Co., Ltd.) is used. The base film 31 and the protective film 4 are made of polyethylene terephthalate (PET). The thickness of the base film 31 is about 50 μm.

The pressure-sensitive adhesive layer 32 has components such as an acrylic polymer and an oligomer (a polymer in which a relatively small number of monomers are bonded). The thickness of the pressure-sensitive adhesive layer 32 is about 50 μm. The pressure-sensitive adhesive layer 32 also contains a photopolymerization initiator that initiates photopolymerization by irradiation with ultraviolet rays. In the pressure-sensitive adhesive layer 32, the components of the pressure-sensitive adhesive layer 32 cause photopolymerization by irradiation with ultraviolet rays, the flexibility of the pressure-sensitive adhesive layer 32 is lost, and the adhesive strength is lowered.

The protective film 4 is a protective laminated film (also referred to as “separator”) for the pressure-sensitive adhesive layer 32, and is peeled off from the first transfer member 3 during use. The thickness of the protective film 4 is about 40 μm. In the present embodiment, the protective film 4 is reused in the reduction of the adhesive strength of the first transfer member shown in FIG. 1 (step S3) (details will be described later with reference to FIG. 2 (d)). ).

In step S1, for example, a sticking device (not shown) for sticking the tape-shaped first transfer member 3 to the substrate 2 shown in FIG. 2A is used. The affixing device is provided with a mounting table for mounting and holding the first transfer member 3 after the protective film 4 shown in FIG. 5 has been peeled off, and an outer peripheral end portion of the substrate 2 provided above the mounting table. It includes a support for supporting, a drive mechanism for raising and lowering the support, and a pressurizing means for pressurizing from the other surface of the substrate 2 (hereinafter, simply referred to as “back surface”). In this case, the surface of the substrate 2 and the pressure-sensitive adhesive layer 32 of the first transfer member 3 face each other with a certain distance.

In step S1, the sticking apparatus attaches the electrode portion 10 (see FIG. 4B) of the micro LED1 formed on the surface of the substrate 2 by lowering the support, and the adhesive layer of the first transfer member 3. It is brought into contact with 32. Then, the pasting device attaches the first transfer member 3 to the substrate 2 by applying pressure from the back surface of the substrate 2. As the bonding load, for example, it is preferable to apply a force selected in the range of 1 to 100 MPa to one micro LED 1 for a selected time in 10 to 300 seconds. In the present embodiment, the optimum value is obtained in advance by an experiment so that the bonding load becomes the optimum value. The sticking device monitors the detection value of the pressure sensor and adjusts the sticking load to the optimum value.

The fact that the first transfer member 3 is attached to the substrate 2 means that the first transfer member 3 is also attached to the surface of the micro LED 1 on the electrode portion 10 side.

FIG. 2A shows a state in which the first transfer member 3 is attached to the substrate 2 in the step S1. FIG. 2A shows a state in which the micro LED 1 is attached to the first transfer member 3 for convenience of explanation. In the present embodiment, even if there is a portion where the first transfer member 3 is attached to the substrate 2 via the micro LED 1, the first transfer member 3 is attached to the substrate 2 as a whole.

Next, in the first transfer (step S2) by the first transfer member shown in FIG. 1, the first transfer member 3 is subjected to laser lift-off to peel off the micro LED 1 from the substrate 2 in the state shown in FIG. 2 (a). The process of transferring the micro LED 1 to one surface (hereinafter, simply referred to as “first surface”) is executed.

The laser lift-off is a means for irradiating the micro LEDs 1 formed on the surface of the substrate 2 with laser light L by pulse oscillation from the back surface of the substrate 2 and peeling each micro LED 1 from the substrate 2. Specifically, in laser lift-off, when the laser beam L is focused and irradiated on the interface region (for example, the peeling layer) of the portion to be peeled off, for example, the interface is accompanied by the phenomenon (ablation) in which nitrogen of GaN is vaporized. The micro LED 1 is detached from the substrate 2 in the region.

In step S2, specifically, the substrate 2 is formed by adjusting parameters such as laser power, irradiation area of laser light L, and number of irradiations based on pulse irradiation by using a device for performing laser lift-off (not shown). The micro LED 1 is peeled off from. Here, as the parameters, the optimum conditions are selected from a pulse laser of 1 Hz to 100 kHz (pulse width: 1 psec to 10 nsec) and an energy density of about 100 to 1000 mJ / cm ² .

When performing laser lift-off in step S2, for example, a picosecond pulse laser having a wavelength of 266 nm, which is a fourth harmonic generation (FHG), is used by a YAG (Yttrium Aluminum Garnet) laser oscillator in the solid UV region. Is preferable.

FIG. 2B schematically illustrates a laser lift-off state. The laser beam L of the pulse laser irradiates the boundary region between the surface of the substrate 2 and the bottom surface of the micro LED 1.

Next, in step S2, the substrate 2 is peeled off from the first transfer member 3 by lifting the substrate 2 after the laser irradiation. As a result, the micro LED 1 is transferred to the first transfer member 3.

FIG. 2C illustrates a state in which the micro LED 1 is transferred to the first transfer member 3. In this case, since the electrode portion 10 of the micro LED1 (see FIG. 4B) is attached to the first surface of the first transfer member 3, the micro LED1 cannot be transferred to the substrate 6 in this state. This is because the electrode portion 10 is not exposed. Therefore, a second transfer process, which will be described later, is required so that the electrode portion 10 is exposed.

Next, in the reduction of the adhesive strength of the first transfer member (step S3), the first transfer member 3 to which the micro LED 1 is transferred is subjected to a treatment for preventing exposure to oxygen, and then ultraviolet rays are applied to the first transfer member 3. Irradiates the transfer member 3 of the above to reduce the adhesive strength of the first transfer member 3.

Specifically, in step S3, in order to perform a process of preventing exposure to oxygen, a process of attaching the protective film 4 to the first surface of the first transfer member 3 after the micro LED 1 is transferred is executed. ..

FIG. 2D illustrates a state in which the protective film 4 is attached to the first surface of the first transfer member 3. That is, in this embodiment, the protective film 4 is reused. As a result, the production cost can be suppressed. Here, attaching the protective film 4 to the first surface of the first transfer member 3 includes attaching the protective film 4 to the micro LED 1. FIG. 2D shows a state in which the protective film 4 is attached to the micro LED 1 for convenience of explanation. As described above, the thickness of the micro LED 1 is on the order of microns, so that the protective film 4 is also attached to the first transfer member 3 in the whole view.

Next, in step S3, when the first transfer member 3 is irradiated with ultraviolet UV rays in order to reduce the adhesive force of the first transfer member 3, an ultraviolet curing reaction by photopolymerization occurs in the pressure-sensitive adhesive layer 32. In the ultraviolet curing reaction, in the presence of the photopolymerization initiator, the photopolymerization initiator first becomes a radical (a chemical species having an unpaired electron) by irradiation with ultraviolet rays. Subsequently, the radical is activated by reacting with a polymer or oligomer having a polymerizable group as a component of the pressure-sensitive adhesive layer 32. Then, the pressure-sensitive adhesive layer 32 is cured by the chain-bonding of these polymers and oligomers. As a result, the adhesive strength of the first transfer member 3 is reduced.

FIG. 2E illustrates a state in which the first transfer member 3 to which the protective film 4 is attached is irradiated with ultraviolet UV rays. In FIG. 2 (e), the ultraviolet UV is irradiated toward the other surface of the first transfer member 3, but the present invention is not limited to this. That is, since the protective film 4 and the base film 31 (see FIG. 5) are made of PET, both of them can transmit ultraviolet UV rays. Therefore, the ultraviolet UV may be irradiated toward the protective film 4 or may be irradiated from both directions, so that the degree of freedom in device design is improved.

In step S3, for example, an ultraviolet irradiation device (not shown) is used to irradiate the first transfer member 3 with ultraviolet rays having a center wavelength of 365 nm. The optimum UV irradiation conditions differ depending on the type of UV peeling tape and UV lamp used. The UV irradiation amount is a value obtained as the integrated light amount, and is calculated by the integrated light amount (mJ / cm ² ) = illuminance (mW / cm ² ) × irradiation time (sec). Here, as a unit conversion, there is a relationship of 1 (mW · h / cm ² ) = 3600 (mJ / cm ² ). In the present embodiment, the optimum ultraviolet irradiation conditions are obtained from the experiment, and for example, the integrated light amount is 1000 (mJ / cm ² ) and the illuminance is 170 (mW / cm ² ). As an example, in the so-called 180 degree peeling test, the adhesive strength decreased from 9 (N / 25 mm) to 0.2 (N / 25 mm) by ultraviolet irradiation.

Here, when ultraviolet UV is irradiated without attaching the protective film 4 to the first surface of the first transfer member 3, oxygen in the air causes radicals in the pressure-sensitive adhesive layer 32 causing the ultraviolet curing reaction. Since it exerts an inactivating action, photopolymerization is inhibited. When the photopolymerization is inhibited, the decrease in adhesive strength is suppressed. Therefore, in the second transfer (step S4) by the second transfer member described later, for example, all the micro LEDs 1 are not transferred and some micros are not transferred. It happens that the LED 1 remains on the substrate 2. This leads to lower yields. In the present embodiment, as a treatment for preventing exposure to oxygen, the protective film 4 is attached to the first surface of the first transfer member 3 to block the invasion of oxygen into the pressure-sensitive adhesive layer 32, so that photopolymerization occurs. It prevents it from being hindered.

When the ultraviolet UV was irradiated from the protective film 4 side, there was a concern that the micro LED 1 shielded the ultraviolet UV from light and the ultraviolet UV was not irradiated to the adhesive layer 32 and the adhesive strength did not decrease. However, by experiments, it was found that if the outer area of the micro LED 1 is set to 50 μm or less on one side, the above-mentioned ultraviolet curing chemical reaction proceeds by the ultraviolet UV irradiated around the micro LED 1.

Next, in step S3, a process of peeling the protective film 4 from the first transfer member 3 is executed. FIG. 2 (f) illustrates a state in which the protective film 4 is peeled off from the first transfer member 3. Since a material whose adhesive strength of the protective film 4 is lower than that of the first transfer member 3 after irradiation with ultraviolet rays is used, the protective film 4 can be easily peeled off from the first transfer member 3 in step S3. can do. From the above, the first half process shown in FIG. 2 is completed.

Next, as the latter half of the process, the process of the second transfer (step S4) by the second transfer member shown in FIG. 1 is executed. 3 (a) and 3 (b) are explanatory views schematically showing the second transfer (step S4) by the second transfer member. Specifically, in step S4, as shown in FIGS. 3A and 3B, a second transfer having a surface having a stronger adhesive force than the first transfer member 3 whose adhesive force is reduced by ultraviolet irradiation. Using the member 5, a process of transferring the micro LED 1 from the first transfer member 3 to the second transfer member 5 is executed by utilizing the difference in adhesive strength. In step S4, a flat plate-shaped adhesive sheet 5a is used as the second transfer member 5, the adhesive sheet 5a is attached to the first transfer member 3, and then the micro LED 1 is first attached by utilizing the difference in adhesive strength. Is transferred from the transfer member 3 of the above to the adhesive sheet 5a. Thereby, in the step S4, the micro LED 1 can be easily transferred from the first transfer member 3 to the pressure-sensitive adhesive sheet 5a which is an example of the second transfer member 5.

FIG. 6 is a schematic cross-sectional view of the second transfer member 5. The pressure-sensitive adhesive sheet 5a, which is an example of the second transfer member 5, includes a base material 51a and pressure-sensitive adhesive layers 52a and 53a laminated on both sides of the base material 51a, respectively. Further, in the pressure-sensitive adhesive sheet 5a, a protective film 4a is attached to the pressure-sensitive adhesive layer 52a. Further, a protective film 4b is attached to the pressure-sensitive adhesive layer 53a. As the adhesive sheet 5a and the protective films 4a and 4b, as an example, a highly heat-resistant adhesive sheet (manufactured by Kyosha Co., Ltd.) that can be used repeatedly is adopted. The adhesive strength of the adhesive sheet 5a is, for example, 1N / 25 mm.

As the base material 51a, a sheet material such as a synthetic resin film can be used. As the synthetic resin film, for example, a polyimide film is preferable from the viewpoint of heat resistance. The pressure-sensitive adhesive layers 52a and 53a are made of a silicone-based pressure-sensitive adhesive resin. The protective films 4a and 4b are laminating films for protecting the pressure-sensitive adhesive layer 32, and are peeled off from the pressure-sensitive adhesive layers 52a and 53a during use. Therefore, the adhesive sheet 5a functions as a single-sided adhesive type when any one of the protective films 4a and 4b is peeled off, and functions as a double-sided adhesive type when both the protective films 4a and 4b are peeled off. do. The film thickness of the base material 51a is, for example, 50 μm, the film thickness of the pressure-sensitive adhesive layers 52a and 53a is, for example, 75 μm, and the film thickness of the protective films 4a and 4b is about several μm.

In step S4, for example, the adhesive sheet 5a is attached to the first transfer member 3 as shown in FIG. 3A. Subsequently, in step S4, when the adhesive sheet 5a is lifted, the adhesive force of the adhesive sheet 5a to the micro LED1 is about 5 times stronger than the adhesive force of the first transfer member 3 to the micro LED1. The first transfer member 3 can be peeled off as shown in b).

Next, in the mounting of the electronic component shown in FIG. 1 (step S5), a process of mounting the micro LED 1 on the substrate 6 from the adhesive sheet 5a, which is an example of the second transfer member 5, is executed.

FIG. 7 is a schematic cross-sectional view of the substrate 6. This schematic cross-sectional view shows the configuration before the micro LED 1 is mounted. The substrate 6 is, for example, a flexible printed circuit board (FPC), in order from the lower layer, a polyimide film base substrate 61, a TFT drive circuit 62, and a predetermined pixel pattern of the TFT drive circuit 62. It is provided with a bump electrode (protruding terminal) 63 provided at a position. The bump electrode 63 has a pair of electrode portions (not shown) corresponding to the pair of electrode portions 1a and 1b (electrode portion 10) of the micro LED1 shown in FIG. 4 (b).

In FIG. 7, the bump electrodes 63 are spaced P3 as the pixel pitch (bump electrode pitch) in one direction (column direction shown in FIG. 8). The pixel pitch defined on the substrate 6 is determined by the distance between the bump electrodes 63. When the micro LED 1 is transferred to the substrate 6, each bump electrode 63 and the electrode portion 10 of the micro LED 1 are electrically connected to each other. An adhesive layer 64 (see FIG. 8) made of an anisotropic conductive adhesive is previously formed around the bump electrode 63 in order to bond and fix the micro LED 1.

3 (c) to 3 (e) are explanatory views schematically showing the mounting of electronic components (step S5). In step S5, for example, a substrate bonding device (not shown) is used to align the adhesive sheet 5a and the substrate 6, attach the adhesive sheet 5a to the substrate 6, and bond and fix the micro LED 1 to the substrate 6. After that, the process of peeling the adhesive sheet 5a from the substrate 6 is executed. As a result, the micro LED 1 can be easily mounted. As a result, the substrate 6 becomes a mounting substrate on which the micro LED 1 is mounted.

The board bonding device mounts a chip such as a micro LED on the board. When electrically connecting the chip surface and the substrate, it is suitable for connecting by protruding terminals (bump electrodes) arranged in an array, instead of connecting by wires as in wire bonding.

Specifically, in step S5, by using a mounting device such as a board bonding device, the adhesive sheet 5a and the board 6 are aligned as shown in FIG. 3 (c). Here, since the position of each bump electrode 63 is important for the substrate 6, the illustration of the base substrate 61 and the TFT drive circuit 62 shown in FIG. 7 is omitted (hereinafter, the same applies). In detail, this alignment is provided at a position where the electrode portions 10 of the plurality of micro LEDs 1 attached on one surface of the adhesive sheet 5a and the micro LEDs 1 are mounted on the substrate 6. It means positioning so as to connect each of the bump electrodes 63. This positioning is performed by image analysis of the position of each micro LED 1 and the position of each bump electrode 63 using an image pickup camera for alignment as an example.

Subsequently, in step S5, the adhesive sheet 5a and the substrate 6 are bonded together as shown in FIG. 3D. In step S5, the detection value of the pressure sensor is monitored and adjusted so that the bonding load becomes a predetermined optimum value. Then, in step S5, a solder layer of Sn or In is formed in advance on the surface of the bump electrode 63, and Au, which is a chemically stable metal, is formed on the electrode portion 10 side of the micro LED1. As a result, the electrode portion 10 of the micro LED 1 and the bump electrode 63 of the substrate 6 are electrically connected to each other by soldering in which an alloy of Au and Sn or Au and In is formed at the interface after abutting. Further, the micro LED 1 is mechanically adhered and fixed to the substrate 6 by the action of the anisotropic conductive adhesive by heating.

Further, in step S5, the micro LED 1 is mounted on the substrate 6 by peeling off the adhesive sheet 5a shown in FIG. 3 (d) (see FIG. 3 (e)). From the above, the latter half of the process shown in FIG. 3 is completed.

FIG. 8 is a plan view of the substrate 6 after the micro LED 1 is mounted. In step S5, since the electrode portion 10 of the micro LED1 (see FIG. 4) and the bump electrode 63 of the substrate 6 (see FIG. 7) are connected, in FIG. 8, the light emitting surface of the micro LED1 is exposed. Will be there. Each micro LED 1 is adhesively fixed to the substrate 6 by an adhesive layer 64. In FIG. 8, as an example, each micro LED 1 is formed in an array of 5 rows and 12 columns. Further, although the bump electrodes 63 of the substrate 6 are hidden and invisible, they are formed in an arrangement of 5 rows and 12 columns. In the substrate 6, the pixel pitch interval in the row direction is P4, and the pixel pitch interval in the column direction is P3.

Here, the array pitch (spacing P1) of the micro LEDs 1 in the row direction shown in FIG. 4A and the pixel pitch (spacing P4) in the row direction of the bump electrode 63 shown in FIG. 8 coincide with each other. Further, the arrangement pitch (spacing P2) of the micro LEDs 1 in the row direction shown in FIG. 4A coincides with the pixel pitch (spacing P3) in the row direction of the bump electrode 63 shown in FIG. The fact that the array pitch of the micro LED1 and the pixel pitch of the bump electrode 63 match is the position of the pair of electrode portions of the bump electrode 63 corresponding to the pair of electrode portions 1a and 1b of the micro LED1 shown in FIG. 4 (b). Means that they match. That is, in the first embodiment, the arrangement pitch of the micro LEDs 1 and the pixel pitch of the bump electrode 63 have a one-to-one relationship.

From the above, according to the first embodiment of the electronic component mounting method of the present invention, in the step of reducing the adhesive force of the first transfer member 3, after the treatment for preventing exposure to oxygen is performed, the ultraviolet rays are first emitted. Since the transfer member 3 is irradiated to reduce the adhesive strength of the first transfer member 3, it is not adversely affected by exposure to oxygen, and electronic components such as the micro LED 1 can easily be used as the first transfer member. It is transferred to No. 3 and can improve the yield at the time of mounting an electronic component such as a micro LED 1.

Further, according to the first embodiment of the electronic component mounting method of the present invention, as a comparative example, the substrate 2 and the substrate 6 are aligned so as to face each other, then bonded, and the substrate 2 is peeled off by laser lift-off. The following points are superior to the method of mounting the micro LED 1 on the substrate 6.

First, in the method of the comparative example, if the substrate 2 such as the sapphire substrate is warped, the focal position of the laser beam shifts, and the micro LED 1 whose laser lift-off does not work remains on the substrate 2 and is mounted on the substrate 6. It can happen that it is not done. On the other hand, according to the first embodiment, since the adhesive sheet 5a and the substrate 6 are bonded together, the problem of warpage of the substrate 2 can be avoided.

Secondly, in the method of the comparative example, the arrangement pitch of the micro LEDs 1 of the substrate 2 needs to be the same as the pixel pitch defined on the substrate 6. On the other hand, in the case of the first embodiment, when a carrier material such as the first transfer member 3 or the adhesive sheet 5a is used, the arrangement pitch of the micro LEDs 1 to be transferred needs to be the same as the pixel pitch of the bump electrode 63. There is no. That is, in the case of the first embodiment, the arrangement pitch of the micro LEDs 1 on the substrate 2 can be refined by narrowing the interval so as to be an integral multiple of 2 or more than the pixel pitch of the bump electrode 63. can.

For example, when the interval P2 of the array pitch shown in FIG. 4A is narrowed so as to be double the interval P3 of the pixel pitch shown in FIG. 8, if P2 = P3 / 2, then. Since the interval P2 of the arrangement pitch is twice narrower than the interval P3 of the pixel pitch, the interval P2 becomes half of the interval P3 (half pitch), and the degree of integration is increased by that amount.

In FIG. 4A, when the interval P2 is set to half the interval P3 (half pitch) in the drawing, the interval cannot be further narrowed, but in the actual substrate 2, for example, the pixel pitch interval P3 Depending on the value, the spacing P2 of the array pitch can be refined by narrowing the spacing so that it is an integral multiple of 2 or more, such as P3 / 2, P3 / 3, and P3 / 4.

Specifically, the electronic component mounting method includes the steps S1 to S5, and corresponds to a pixel pitch defined on the substrate 6 so that electronic components such as micro LEDs 1 can be mounted on a plurality of substrates 6. Further, it may be characterized in that the substrate 2 having electronic components formed on one surface thereof is formed by narrowing the interval so that the arrangement pitch is an integral multiple of 2 or more than the pixel pitch. In this case, the step S1 may be characterized in that the first transfer member 3 whose adhesive strength is reduced by irradiation with ultraviolet rays is attached to the substrate 2.

When this substrate 2 is used, in step S2, the electronic component to be peeled from the substrate 2 is determined according to the mounting position of the electronic component determined based on the pixel pitch, and the electronic component determined from the substrate 2 is determined. The electronic component may be transferred to one surface of the first transfer member 3 by selective laser lift-off.

As a result, in the above step S2, only the micro LED1 used for mounting as an electronic component can be lifted off, and the surplus micro LED1 can be used for the substrate to be mounted next, which leads to cost reduction. Further, the micro LED 1 formed on the substrate 2 can increase the degree of integration as much as possible.

Further, in the first embodiment, as a process for preventing exposure to oxygen, ultraviolet UV is applied after the removable protective film 4 is attached to the first surface of the first transfer member 3 to which the micro LED 1 is transferred. Although the transfer member 3 of 1 is irradiated, the present invention is not limited to this.

FIG. 9 is an explanatory diagram showing an example of a process for preventing exposure to oxygen. This example is characterized in that the process S3 of the electronic component mounting method shown in FIG. 1 is changed as follows. In this example, the first transfer member 3 is irradiated with ultraviolet UV rays in a vacuum chamber 7 having a preset degree of vacuum. In the vacuum chamber 7 shown in FIG. 9, for example, the oxygen concentration is preferably 5% or less, more preferably 2% or less. If the oxygen concentration is set to this level, the effect of preventing exposure to oxygen can be obtained without using the protective film 4 as shown in FIG. 2 (c).

Therefore, even when an example of the treatment for preventing exposure to oxygen as shown in FIG. 9 is adopted, the micro LED 1 is easily transferred to the first transfer member 3, and when the electronic component such as the micro LED 1 is mounted. Yield can be improved.

However, in this example, in the vacuum chamber 7 having a preset degree of vacuum, after the protective film 4 is attached to the first surface of the first transfer member 3 to which the micro LED 1 is transferred, the ultraviolet UV is applied. The transfer member 3 of 1 may be irradiated. It is possible to prevent air bubbles from being mixed when the protective film 4 is attached, and it is possible to obtain an effect of further preventing exposure to oxygen.

FIG. 10 is an explanatory diagram showing another example of the treatment for preventing exposure to oxygen. Another example is characterized in that the process S3 of the electronic component mounting method shown in FIG. 1 is changed as follows. In another example, the first transfer member 3 is irradiated with ultraviolet UV rays in a nitrogen gas chamber 8 filled with nitrogen. In FIG. 10, each dot shown in the nitrogen gas chamber 8 schematically represents a nitrogen (N ₂ ) gas (nitrogen gas). Since the inside of the nitrogen gas chamber 8 shown in FIG. 10 is filled with nitrogen, for example, it is possible to prevent exposure to oxygen, and it is not necessary to attach the protective film 4 in step S3.

Therefore, even when another example of the treatment for preventing exposure to oxygen is adopted, the micro LED 1 is easily transferred to the first transfer member 3, and the yield at the time of mounting an electronic component such as the micro LED 1 is improved. be able to.

[Second Embodiment]
Next, a second embodiment of the electronic component mounting method according to the present invention will be described. The same configurations described in the first embodiment of the electronic component mounting method are designated by the same reference numerals, and the description thereof will be omitted or simplified.

In the second embodiment of the electronic component mounting method, the processes of steps S4 to S5 are different from those of the first embodiment in the flow chart (see FIG. 1) shown in the process of the first embodiment. Therefore, the description of the processes of steps S1 to S3 described above will be omitted, and the processes of steps S4 to S5 will be described by diverting the flow chart shown in FIG.

FIG. 11 is an explanatory diagram showing a second transfer process by the second transfer member in the second embodiment of the electronic component mounting method according to the present invention. 11 (a) shows the state before transcription, (b) shows the state immediately after the start of transcription, and (c) shows the state after the end of transcription. After the execution of the above-mentioned steps S1 to S3, in the second transfer by the second transfer member (step S4), the roller-shaped adhesive roller 5b is used as the second transfer member 5, and the adhesive roller 5b is rotated. By causing the micro LED 1 to come into contact with the adhesive roller 5b transferred onto the first transfer member 3, a process of transferring the micro LED 1 from the first transfer member 3 to the adhesive roller 5b is executed. In step S4, the transfer apparatus is used, which is not shown in the overall configuration. This transfer device includes the adhesive roller 5b and the stage 9 having a mechanism for moving the mounted object in the triaxial (XYZ) direction in order to perform not only the above processing but also the processing of the step S5 described later. .. The mounted object is the first transfer member 3 used in the step S4 and the substrate 6 used in the step S5 described later.

Specifically, in FIG. 11, in step S4, the adhesive roller 5b and the first transfer member 3 are relatively moved, and each time the adhesive roller 5b rotates at a predetermined angle, the adhesive roller 5b is placed on the stage 9. It is characterized in that the micro LED 1 is transferred from the placed first transfer member 3 to the adhesive roller 5b.

Here, moving the adhesive roller 5b and the first transfer member 3 relative to each other means, for example, that (1) the first transfer member 3 is made stationary on the stage 9 while rotating the adhesive roller 5b. The adhesive roller 5b is moved in a uniaxial direction (left direction in the figure), and (2) the adhesive roller 5b is driven only by rotation, and the first transfer member 3 mounted on the stage 9 is uniaxially driven. Includes moving in the direction (to the right in the figure). In step S4, the above (1) is adopted. Here, when the above (1) is adopted, a mechanism for moving the adhesive roller 5b in the uniaxial direction is separately incorporated in the transfer device.

In the adhesive roller 5b shown in FIG. 11A, an adhesive sheet 52b is attached to the roller 51b and the peripheral surface of the roller 51b. The adhesive roller 5b rotates around the rotation shaft 53b. The adhesive sheet 52b is the same as the adhesive sheet 5a described above (high heat resistant adhesive sheet (manufactured by Kyosha Co., Ltd.)). In the second embodiment, since the adhesive sheet 52b is used as a double-sided tape, one adhesive layer (not shown) of the adhesive sheet 52b is attached to the roller 51b, and the micro LED1 is attached to the other adhesive layer (not shown). Will be stuck. Therefore, the shape of the adhesive sheet 52b is a roller shape.

In FIG. 11A, in step S4, the micro LED 1 on the first transfer member 3 mounted on the stage 9 and the adhesive roller 5b are aligned with each other. In step S4, the micro LED 1 on the first transfer member 3 is confirmed by an image pickup camera and aligned.

As an example, since each micro LED 1 is transferred to the first transfer member 3 using the substrate 2 shown in FIG. 4, the adhesive rollers are used as one row of micro LEDs 1 in a single transfer. It will be transferred to 5b. This is because, as shown in FIG. 4, the arrangement of the micro LEDs 1 on the substrate 2 is 5 rows and 12 columns, and 5 micro LEDs 1 are formed in one column.

In step S4, in FIG. 11B, the stage 9 is raised vertically upward, and the adhesive sheet 52b provided on the roller surface of the roller-shaped adhesive roller 5b is brought into contact with the micro LED1. Under this state, the adhesive force of the adhesive sheet 52b to the micro LED 1 is about 5 times stronger than the adhesive force to the micro LED 1 attached to the first transfer member 3. Therefore, in step S4, the micro LED1 can be transferred to the adhesive sheet 52b by rotating the adhesive roller 5b and moving the adhesive roller 5b in the uniaxial direction (left direction in the figure).

In this way, in step S4, while rotating the adhesive roller 5b, the adhesive roller 5b is moved in the uniaxial direction (left direction in the figure) as shown in FIG. 11 (b). As shown in, all the micro LEDs 1 can be easily transferred to the adhesive roller 5b via the adhesive sheet 52b. In order to make the explanation easy to understand, the micro LEDs 1 are transferred to the adhesive roller 5b at an angle pitch of 30 degrees for each row. However, in reality, the angular pitch is determined according to the number of micro LEDs 1 to be transferred.

Here, when the step S4 is completed, the transfer device returns the adhesive roller 5b to the set position in the initial state shown in FIG. 11A, lowers the stage 9, and then removes the first transfer member 3. , The substrate 6 used in the next step S5 is placed on the stage 9.

Next, the process of mounting the electronic component (process S5) is executed. FIG. 12 is an explanatory diagram showing a process of mounting electronic components in the second embodiment of the electronic component mounting method according to the present invention. In step S5, the adhesive roller 5b is rotated by a predetermined angle by using the transfer device, and the adhesive roller 5b (second transfer member 5) and the substrate 6 are relatively moved to adhere to each other. Every time the roller 5b rotates at a predetermined angle, a process of transferring the micro LED 1 from the adhesive roller 5b to the substrate 6 is executed. The relative movement of the adhesive roller 5b and the substrate 6 means that (1) the adhesive roller 5b is only rotationally driven and the substrate 6 is moved in the uniaxial direction (right direction in the figure), and (2). This includes resting the substrate 6 on the stage 9, driving the adhesive roller 5b to rotate, and moving the adhesive roller 5b in the uniaxial direction (left direction in the figure). In step S5, the above (1) is adopted.

In step S5, as shown in FIG. 12A, the positions of the one row of micro LEDs transferred to the adhesive sheet 52b and the one row of bump electrodes 63 of the substrate 6 are aligned. Specifically, in step S5, the bump electrode 63 of the substrate 6 and the adhesive sheet 52b to which each micro LED 1 is transferred are confirmed by an image pickup camera and aligned. FIG. 12A shows a state of alignment. That is, the bump electrodes 63 in a row of the substrate 6 and the electrode portions 10 of the micro LEDs 1 in a row facing in the vertical direction are aligned with each other. In FIG. 12, the adhesive layer 64 shown in FIG. 8 is not shown.

Subsequently, in step S5, by raising the stage 9, the electrode portion 10 (see FIG. 4B) of the first row of micro LEDs 1 and the bump electrode 63 of one row are brought into contact with each other. In this case, in the same manner as in the first embodiment, in step S5, a solder layer of Sn or In is formed in advance on the surface of the bump electrode 63, and the electrode portion 10 side of the micro LED 1 is chemically stable. Au, which is a metal, is formed. After that, in step S5, the electrode portion 10 of the micro LED1 and the bump electrode 63 are electrically connected by soldering one row at a time to form an alloy of Au and Sn or Au and In at the interface. do. Further, the adhesive layer 64 (see FIG. 8) surrounds the periphery of the micro LED1 by local heating to be adhered to the periphery of the micro LED 1 in each row, and the micro LED 1 is adhered and fixed. FIG. 12B shows a state in which the first row of micro LEDs 1 are electrically and mechanically connected to the substrate 6.

Next, in step S5, a row of micro LEDs 1 are sequentially mounted on the substrate 6 while synchronizing the moving speed of the stage 9 and the rotation speed of the adhesive roller 5b. Specifically, since the micro LEDs 1 are transferred to the adhesive roller 5b in each row at an angle pitch of 30 degrees in the above-mentioned step S4, the rotation speed of rotating the adhesive roller 5b counterclockwise by 30 degrees , Synchronize with the movement speed of stage 9 (pointing to the right in the figure). Here, every time the adhesive roller 5b is rotated counterclockwise by 30 degrees, the arrangement pitch of the micro LEDs 1 moves by the distance of the interval P2, so that the stage 9 has the interval P3 as the pixel pitch of the bump electrode 63 of the substrate 6. Move only the distance. As a result, the arrangement pitch of the micro LED 1 and the pixel pitch of the bump electrode 63 can be matched.

In this case, when the moving speed of the stage 9 and the rotation speed of the adhesive roller 5b are synchronized, the adhesive force of the substrate 6 is stronger than the adhesive force of the adhesive roller 5b with respect to the first row of micro LEDs 1. , These micro LEDs 1 are transferred from the adhesive roller 5b to the substrate 6 and mounted.

Then, when the adhesive roller 5b is rotated by 30 degrees, the next row of micro LEDs 1 comes into contact with each other, and the electrode portion 10 of the micro LEDs 1 and the bump electrode 63 on the substrate 6 are positioned. Then, in step S5, as described above, the electrode portion 10 of the next row of micro LEDs 1 and the bump electrode 63 of the next row are electrically and mechanically connected to the substrate 6. FIG. 12 (c) shows a state in which the next row of micro LEDs 1 are electrically and mechanically connected to the substrate 6 by adhesive fixing.

After that, by repeating the same process, all the micro LEDs 1 can be mounted on the substrate 6. FIG. 12D shows a state in which all the micro LEDs 1 are mounted on the substrate 6. Note that FIG. 12 (d) shows a state in which the stage 9 has completed the movement in the uniaxial direction (right direction in the figure) for convenience of explanation, and the positions of the adhesive rollers 5b are shown in FIGS. 12 (a) to 12 (c). ) Means that it is in the same position.

Here, in the first embodiment, the pressure-sensitive adhesive sheet 5a and the substrate 6 are surface-adhered and bonded to each other, and then the micro LED 1 is transferred and bonded and fixed to the substrate 6. On the other hand, in the second embodiment, the micro LEDs 1 in a row of the adhesive rollers 5b are linearly adhered and fixed to the substrate 6, so that the adhesive sheet 5a is surface-based on the substrate 6 as in the first embodiment. It is not necessary to make them adhere to each other, and it is not necessary to remove the adhesive sheet 5a from the substrate 6 as in the first embodiment.

From the above, according to the second embodiment of the electronic component mounting method of the present invention, as in the first embodiment, in the step of reducing the adhesive strength of the first transfer member 3, a treatment for preventing exposure to oxygen was performed. Later, the first transfer member 3 is irradiated with ultraviolet rays to reduce the adhesive strength of the first transfer member 3, so that the first transfer member 3 is not adversely affected by exposure to oxygen, and electronic components such as the micro LED 1 are easy to use. It is transferred to the first transfer member 3 and can improve the yield at the time of mounting an electronic component such as a micro LED 1.

[Manufacturing method of micro LED display]
Next, a method of manufacturing a micro LED display will be described. FIG. 13 is a flow chart showing a process of a method for manufacturing a micro LED display according to the present invention. The method for manufacturing a micro LED display is characterized in that the above-mentioned electronic component mounting method is adopted. That is, in the present manufacturing method, after executing the above-mentioned electronic component mounting method described above, power is supplied from the outside by forming a phosphor cell array 12 in which the phosphor cells 12a are arranged in a matrix on the upper layer of the substrate 6. To manufacture a micro LED display (see FIG. 18) capable of full-color display.

In this embodiment, for example, a method of realizing full-color display by combining an LED that emits light having a short wavelength such as an ultraviolet light emitting diode (UV-LED) and an RGB phosphor is adopted. In this case, on the light emitting surface side of the micro LED 1, a phosphor cell 12a having an RGB phosphor that converts light in the ultraviolet or blue wavelength band into a predetermined corresponding color is provided (see FIG. 17).

Specifically, in the mounting of the micro LED (step S11), each step of the electronic component mounting method described with reference to FIG. 1 is executed. As a result, the micro LED 1 is mounted on the substrate 6 (see FIG. 8).

Next, the formation of the flattening film (step S12) will be described. In step S12, a flat plate-shaped flattening film 11 for adhering and supporting a fluorescent material cell array 12 (see FIG. 16), which will be described later, is formed on the substrate 6. The flat plate-shaped flattening film 11 has a function as a photosensitive thermosetting adhesive layer.

FIG. 14 is an explanatory diagram showing a process of forming a flattening film. (A) is a plan view of the substrate 6 in which the flattening film 11 is further laminated. (B) is a cross-sectional view taken along the line AA of the three micro LEDs 1 in the region R1 surrounded by the broken line in (a). In step S12, for example, a microdispenser is used to apply the photosensitive thermosetting adhesive onto the substrate 6 while controlling the height direction to be constant.

Subsequently, in step S12, the photosensitive thermosetting adhesive is exposed by photolithography to form a flattening film 11. In FIG. 14B, the bump electrode 63 and the electrode portion 10 of the micro LED 1 are connected to the substrate 6, and the adhesive layer 64 adheres and fixes the micro LED 1 around the bump electrode 63. Further, the flattening film 11 flattens the substrate 6. At this time, it is preferable that the photosensitive thermosetting adhesive is not formed on the light emitting surface 1d of the micro LED1 shown in FIG. 14 (b).

Next, the formation of the fluorophore cell array (step S13) will be described. In step S13, a phosphor cell array 12 having a plurality of phosphor cells 12a whose arrangement is determined according to the arrangement of the micro LEDs 1 is formed on the sapphire substrate 2a.

FIG. 15 is an explanatory diagram showing a process of forming a fluorescent substance cell. Step S13 comprises forming a rib structure and filling with a fluorescent material. As shown in FIG. 15, the formation of the rib structure includes the formation of the partition wall 14, the formation of the metal film 13, and the laser processing of the metal film 13. Specifically, in step S13, a fluorescent resist is applied to the entire surface of the sapphire substrate 2a, and a pattern of the partition wall 14 is formed by photolithography.

Subsequently, in step S13, in order to prevent color mixing, the inside of the partition wall 14 is metal-coated with a metal film 13, and only the bottom surface is irradiated with a pulse laser to peel off the metal film 13 by ablation. Further, in step S13, a fluorescent material layer 12R filled with a red fluorescent dye, a fluorescent material layer 12G filled with a green fluorescent dye, and a fluorescent material layer 12B filled with a blue fluorescent dye are formed. As a result, the phosphor cell 12a is formed. In this way, a fluorescent material cell array 12 having a plurality of fluorescent material cells 12a in a matrix is formed on the sapphire substrate 2a.

FIG. 16 is a plan view of the fluorescent material cell array 12. The phosphor cell array 12 is a matrix of fluorescent cell 12a having a fluorescent light emitting layer composed of a fluorescent material layer 12R, a fluorescent material layer 12G, and a fluorescent material layer 12B arranged on a sapphire substrate 2a.

Next, the formation of the micro LED display (step S14) will be described. FIG. 17 is an explanatory diagram showing a process of forming a micro LED display. In step S14, by using a mounting device such as the substrate bonding device, first, the substrate 6 on which the micro LED 1 is mounted and the substrate 2a having the phosphor cell array 12 are bonded.

FIG. 17A shows a state in which the substrate 6 on which the micro LED 1 is mounted and the substrate 2a having the phosphor cell array 12 are bonded together. However, in FIG. 17, for the sake of clarity, the fluorescent cell 12a, which is a constituent unit of the fluorescent cell array 12, is focused on, and the fluorescent cell 12a and one of the cross-sectional views taken along the line BB shown in FIG. A substrate 6 including three micro LEDs 1 located below the micro LED 1 is drawn. In this case, the three micro LEDs 1 of the substrate 6 and the fluorescent material layers 12R, 12G, and 12B of one fluorescent cell 12a are connected to each other. The reference numerals shown in FIG. 17 have already been described with reference to FIGS. 14 (b) and 15.

In step S14, the flattening film 11 is heat-cured and the phosphor cell array 12 is fixed to the substrate 6. Subsequently, in step S14, the phosphor cell array 12 is laser lifted off from the sapphire substrate 2a. FIG. 17B schematically shows the laser lift-off by the step S14. As a result, the micro LED display 100 is formed.

FIG. 18 is a plan view of the micro LED display 100. In the micro LED display 100, a phosphor cell array 12 having a plurality of phosphor cells 12a is formed on a substrate 2 on which a micro LED 1 is mounted.

Based on the above, in the present embodiment, the yield at the time of mounting electronic components such as the micro LED 1 is improved by applying the manufacturing method of the micro LED display that employs the electronic component mounting method of mounting the plurality of micro LEDs 1 on the substrate 6. It is possible to manufacture a micro LED display.

Thereby, the micro LED display manufactured by the method for manufacturing the micro LED display of the present invention can be distributed as a display panel. Further, for example, when a micro LED display manufactured by the method for manufacturing a micro LED display of the present invention is incorporated as a display unit at the manufacturing stage of an electronic device having a display unit (for example, a smartphone), the micro LED display is used. By receiving the power supply, the image can be displayed in full color.

The above-described embodiments are shown to the extent that the present invention can be understood and implemented, and the present invention is not limited thereto. The present invention can be variously modified and modified as long as it does not deviate from the scope of the technical idea shown in the claims.

1 ... Micro LED (electronic component)
2 ... Light-transmitting substrate 3 ... First transfer member 4 ... Protective film 5 ... Second transfer member 5a ... Adhesive sheet 5b ... Adhesive roller 6 ... Substrate 7 ... Vacuum chamber 8 ... Nitrogen gas chamber 11 ... Flattening film 12 ... Fluorescent cell array 12a ... Fluorescent cell 100 ... Micro LED display

Claims (9)

It is an electronic component mounting method that mounts electronic components on a board on which a circuit is mounted.
A step of attaching a first transfer member whose adhesive strength is reduced by ultraviolet irradiation to a light-transmitting substrate in which a plurality of electronic components are formed according to a predetermined arrangement on one surface.
A step of transferring the electronic component to one surface of the first transfer member by a laser lift-off that separates the electronic component from the light transmissive substrate.
The first transfer member to which the electronic component is transferred is subjected to a treatment for preventing exposure to oxygen, and then the first transfer member is irradiated with ultraviolet rays to obtain an adhesive force of the first transfer member. And the process of reducing
Using a second transfer member having a stronger adhesive force than the first transfer member having a reduced adhesive force, the electronic component can be moved from the first transfer member to the second transfer member by utilizing the difference in the adhesive force. The process of transferring to the transfer member of
The step of mounting the electronic component on the substrate from the second transfer member, and
An electronic component mounting method characterized by including. In the step of reducing the adhesive strength of the first transfer member, after a protective film is attached to one surface of the first transfer member to which the electronic component is transferred, ultraviolet rays are applied to the first transfer member. The electronic component mounting method according to claim 1, wherein the irradiation is performed. The electronic component according to claim 1, wherein in the step of reducing the adhesive force of the first transfer member, ultraviolet rays are irradiated to the first transfer member in a vacuum chamber having a preset vacuum degree. Implementation method. The electronic component mounting according to claim 1, wherein in the step of reducing the adhesive strength of the first transfer member, ultraviolet rays are irradiated to the first transfer member in a nitrogen gas chamber filled with nitrogen. Method. In the step of transferring to the second transfer member, a flat plate-shaped pressure-sensitive adhesive sheet is used as the second transfer member, the pressure-sensitive adhesive sheet is attached to the first transfer member, and the first transfer member is attached. The method for mounting an electronic component according to claim 1, wherein the electronic component is transferred from the first transfer member to the pressure-sensitive adhesive sheet by peeling off the electronic component. In the step of mounting the electronic component on the substrate, the adhesive sheet and the substrate are aligned, the adhesive sheet is attached to the substrate, the electronic component is bonded and fixed to the substrate, and then the adhesive is attached. The electronic component mounting method according to claim 5, wherein the sheet is peeled off from the substrate. In the step of transferring to the second transfer member, a roller-shaped adhesive roller is used as the second transfer member, and the adhesive roller is rotated to obtain the electronic component on the first transfer member and the electronic component. The component mounting method according to claim 1, wherein the electronic component is transferred from the first transfer member to the adhesive roller by contacting the adhesive roller. In the step of mounting the electronic component on the substrate, the adhesive roller is rotated by a predetermined angle, and the adhesive roller and the substrate are relatively moved so that the adhesive roller rotates at a predetermined angle. The component mounting method according to claim 7, wherein the electronic component is adhesively fixed on the substrate each time. It is a manufacturing method of a micro LED display capable of full-color display.
A step of attaching a first transfer member whose adhesive strength is reduced by ultraviolet irradiation to a light transmissive substrate in which a plurality of micro LEDs are formed according to a predetermined arrangement on one surface.
A step of transferring the micro LED to one surface of the first transfer member by a laser lift-off that separates the micro LED from the light transmissive substrate.
After the first transfer member to which the micro LED is transferred is subjected to a treatment for preventing exposure to oxygen, the first transfer member is irradiated with ultraviolet rays, and the adhesive force of the first transfer member is obtained. And the process of reducing
Using a second transfer member having a stronger adhesive force than the first transfer member having a reduced adhesive force, the micro LED can be transferred from the first transfer member to the second transfer member by utilizing the difference in the adhesive force. The process of transferring to the transfer member of
The process of mounting the micro LED from the second transfer member on the substrate on which the circuit is mounted, and
The process of forming a flat plate-shaped flattening film on the substrate on which the micro LED is mounted, and
A step of forming a phosphor cell array having a plurality of phosphor cells whose arrangement is determined according to the arrangement of the micro LEDs on the substrate on which the flattening film is formed.
A method for manufacturing a micro LED display, which comprises.

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