CN115881759A - Method for manufacturing display device - Google Patents

Abstract

The present invention relates to a method for manufacturing a display device. The performance of the display device is improved. The manufacturing method comprises the following steps: (a) Preparing a first substrate on which a plurality of first inorganic light emitting elements are arranged in a matrix and an array substrate on which a plurality of first terminals are formed; (b) Measuring each of the thickness of the first substrate, the thickness of the one or more first inorganic light emitting elements, and the thickness of the array substrate; (c) Pressing each of the plurality of first inorganic light emitting elements against the array substrate in a state where the first substrate held by the first stage and the array substrate held by the second stage are opposed to each other, and electrically connecting the plurality of first terminals of the array substrate and the plurality of first inorganic light emitting elements; (d) And (c) controlling, based on the result measured in the step (b), the press-in amount by which each of the plurality of first inorganic light emitting elements is pressed against the array substrate.

Description

Method for manufacturing display device

Technical Field

The present invention relates to a manufacturing technique of a display device.

Background

As a display device, there is an LED (Light Emitting diode) display device in which inorganic Light Emitting diode elements as self-luminous elements are arranged in a matrix on a substrate (see, for example, patent document 1 (japanese patent laid-open No. 2020-67626)). Further, as a more sophisticated display device, there is a micro LED display device using minute inorganic light emitting diode elements called micro LEDs (for example, see patent document 2 (japanese patent application laid-open No. 2019-36719)).

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2020-67626

Patent document 2: japanese patent laid-open publication No. 2019-36719

Disclosure of Invention

Problems to be solved by the invention

The manufacturing process of the LED display device and the manufacturing process of the micro LED display device include a process of mounting a plurality of LED elements (or micro LED elements) on a substrate. In the step of mounting the plurality of LED elements, the plurality of LED elements are pressed against the substrate. Control of the pressing force (pressing force) of the plurality of LED elements against the substrate at this time is important. For example, if the pressing force is too large, the LED elements and the substrate may be damaged. In addition, if the pressing force is too small, the reliability of electrical connection between the terminals formed on the substrate and the LED element is lowered.

The invention aims to provide a technique for improving the performance of a display device using a plurality of inorganic light emitting diode elements.

Means for solving the problems

A method for manufacturing a display device according to an embodiment of the present invention includes the following steps. (a) Preparing a first substrate on which a plurality of first inorganic light emitting elements are arranged in rows and columns and an array substrate on which a plurality of first terminals are formed. (b) And measuring each of the thickness of the first substrate, the thickness of one or more first inorganic light emitting elements among the plurality of first inorganic light emitting elements, and the thickness of the array substrate. (c) And a step of electrically connecting the plurality of first terminals of the array substrate and the plurality of first inorganic light emitting elements by pressing each of the plurality of first inorganic light emitting elements against the array substrate in a state where the first substrate held on the first stage and the array substrate held on the second stage are opposed to each other. (d) And (c) peeling the first substrate from the plurality of first inorganic light emitting elements after the step (c). In the step (c), the intensity with which each of the plurality of first inorganic light emitting elements is pressed against the array substrate is controlled based on the result measured in the step (b).

Drawings

Fig. 1 is a plan view showing an example of a configuration of a display device according to an embodiment.

Fig. 2 is a circuit diagram showing an example of the configuration of the circuit around the pixel shown in fig. 1.

Fig. 3 is an enlarged cross-sectional view showing an example of a peripheral structure of each of the LED elements arranged in each of the plurality of pixels of the display device shown in fig. 1.

Fig. 4 is an enlarged cross-sectional view showing a modification of the LED element shown in fig. 3.

Fig. 5 is an explanatory diagram illustrating a flow of a manufacturing process of the display device shown in fig. 1.

Fig. 6 is a plan view schematically showing a substrate prepared in the step of preparing the LED holding substrate shown in fig. 5.

Fig. 7 is a cross-sectional view schematically showing the array substrate SUB1 prepared in the step of preparing the array substrate shown in fig. 5.

Fig. 8 is a cross-sectional view schematically showing an example of a measurement site in the step of measuring the thickness shown in fig. 5.

Fig. 9 is an explanatory diagram illustrating an example of a thickness measuring method in the thickness measuring step shown in fig. 5.

Fig. 10 is a cross-sectional view schematically showing a state in which the substrate on which the first inorganic light emitting elements are arranged is pressed against the array substrate in the step of mounting the first LED elements shown in fig. 5.

Fig. 11 is a cross-sectional view schematically showing a state where the holding substrate is peeled off from the plurality of first inorganic light emitting elements in the step of peeling the first holding substrate shown in fig. 5.

Fig. 12 is a cross-sectional view schematically showing a state in which the substrate on which the second inorganic light emitting elements are arranged is pressed against the array substrate in the step of mounting the second LED elements shown in fig. 5.

Fig. 13 is a cross-sectional view schematically showing a state where the holding substrate is peeled from the plurality of second inorganic light emitting elements in the step of peeling the second holding substrate shown in fig. 5.

Fig. 14 is a cross-sectional view schematically showing a state in which the substrate on which the third inorganic light emitting elements are arranged is pressed against the array substrate in the step of mounting the third LED element shown in fig. 5.

Fig. 15 is a cross-sectional view schematically showing a state where the holding substrate is peeled from the plurality of third inorganic light emitting elements in the step of peeling the third holding substrate shown in fig. 5.

Fig. 16 is a cross-sectional view schematically showing a state before mounting on an array substrate using a holding substrate that holds a plurality of types of LED elements simultaneously, according to the modification of fig. 10.

Description of the reference numerals

5. Control circuit

6. Driving circuit

10. SS1, SS2, SS3, SS4 substrates

10b, 10f, 20b, 20f, 51b, 51t plane

11. Inorganic insulating layer

12. Organic insulating layer

13. Organic insulating layer

20. 20M1 LED element (inorganic light emitting element)

20E electrode

20EA anode

20EK cathode

21. First inorganic light emitting element

22. Second inorganic light emitting element

23. Third inorganic light emitting element

30. 30H, 30L, 31, 32, 33 terminal

40. Conductive bonding member

50A, 50B sensor head

51. Workpiece

52. Laser

Distance 53A, 53B

53C separation distance

61. 62 working table

61h, 62h holding surface

BCT output switch

Cad auxiliary capacitor

Cs holding capacitance

DA display area

DRT drive transistor

DSP1 display device

EK cathode

GL, GLA, GLB scanning signal line

GLR reset wiring

Gsb, gsr, gss control signals

IC driver

LED micro-scale

PFA peripheral region

PIX pixel

Potential of PVD, PVS

RST reset wiring switch

Under surfaces of SS1b, SS2b, SS3b, SS4b

Upper surfaces of SS1t, SS2t, SS3t and SS4t

SST pixel switch

SUB1 array substrate

SUBb surface (second surface)

SUBt surface (first surface)

VL image signal line

Vsg image signal

Detailed Description

Embodiments of the present invention will be described below with reference to the drawings. It should be noted that the present disclosure is merely an example, and appropriate modifications that are obvious to those skilled in the art and that have the gist of the invention are naturally included in the scope of the present invention. In addition, although the drawings schematically show the width, thickness, shape, and the like of each part as compared with the actual form in order to make the description clearer, the drawings are merely examples and do not limit the explanation of the present invention. In the present specification and the drawings, the same or corresponding reference numerals are given to the same elements as those described in the previous drawings, and detailed description thereof may be omitted as appropriate.

In the following embodiments, a micro LED display device including a plurality of micro LED elements will be described as an example of a display device using a plurality of inorganic light emitting elements. The micro LED element has an advantage that a high-definition image can be displayed because the size (outer diameter size) of the element is small as compared with a general LED element. However, since the micro LED element has a small size, a margin of a pressing force to be controlled in a light emitting diode element mounting process described later is small.

An Organic Light-Emitting Diode (OLED) is a Light-Emitting Diode (led) as a self-Light-Emitting element. The inorganic light emitting diode element (micro LED element) described in the following embodiments is different from the organic light emitting diode element.

< display device >

First, a configuration example of a micro LED display device as a display device of the present embodiment will be described. Fig. 1 is a plan view showing an example of a configuration of a display device according to an embodiment. In fig. 1, the boundary between the display area DA and the peripheral area PFA, the control circuit 5, the drive circuit 6, and the plurality of pixels PIX are indicated by two-dot chain lines. Fig. 2 is a circuit diagram showing an example of the configuration of a circuit around the pixel shown in fig. 1.

As shown in fig. 1, the display device DSP1 of the present embodiment includes a display area DA, a peripheral area PFA located around the display area DA, and a plurality of pixels PIX arranged in a matrix in the display area DA. The display device DSP1 includes a substrate 10, a control circuit 5 formed on the substrate 10, and a drive circuit 6 formed on the substrate 10.

The control circuit 5 is a control circuit that controls driving of the display function of the display device DSP 1. The control Circuit 5 is, for example, a driver IC (Integrated Circuit) mounted on the substrate 10. In the example shown in fig. 1, the control circuit 5 is disposed along one of the four sides of the substrate 10. In the example of the present embodiment, the control circuit 5 includes a signal line driving circuit that drives the video signal lines VL (see fig. 2) connected to the plurality of pixels PIX. However, the position and configuration example of the control circuit 5 are not limited to the example shown in fig. 1, and there are various modifications. For example, in fig. 1, a circuit board such as a flexible board may be connected to a position shown as the control circuit 5, and the driver IC may be mounted on the circuit board. In addition, for example, a signal line driver circuit for driving the video signal lines VL may be formed separately from the control circuit 5.

The drive circuit 6 is a circuit that drives the scanning signal lines GL in the plurality of pixels PIX. The drive circuit 6 drives the plurality of scanning signal lines GL based on a control signal from the control circuit 5. In the example shown in fig. 1, the drive circuits 6 are arranged along two long sides of the four sides of the substrate 10. However, the position and configuration example of the drive circuit 6 are not limited to the example shown in fig. 1, and there are various modifications. For example, in fig. 1, a circuit board such as a flexible board may be connected to a position shown as the control circuit 5, and the drive circuit 6 may be mounted on the circuit board.

Next, a circuit configuration example of the pixel PIX will be described with reference to fig. 2. Fig. 2 representatively shows one pixel PIX, and each of the plurality of pixels PIX shown in fig. 1 includes the same circuit as the pixel PIX shown in fig. 2. Hereinafter, a circuit including the switch, the capacitor, and the LED element 20 included in the pixel PIX may be referred to as a pixel circuit. The pixel circuit is a voltage signal type circuit for controlling the light emission state of the LED element 20 based on a video signal Vsg supplied from the control circuit 5 (see fig. 1).

As shown in fig. 2, the pixel PIX includes an LED element 20. The LED element 20 is the above-described micro light emitting diode. The LED element 20 includes an anode 20EA (see fig. 3 described later) and a cathode EK (see fig. 3 described later). The anode 20EA and the cathode 20EK of the LED element 20 are electrically connected to the terminal 30 of the pixel PIX, respectively. In the example shown in fig. 2, the cathode 20EK of the LED element 20 is connected to the terminal 30L, and the anode 20EA of the LED element 20 is connected to the terminal 30H. The terminal 30L is supplied with a relatively low fixed potential (low potential) PVS, and the terminal 30H is supplied with a fixed potential (high potential) PVD higher than the potential supplied to the terminal 30L.

The pixel PIX includes an output switch BCT, a driving transistor DRT, and a pixel switch SST. The output switch BCT is a transistor that controls the light emission time of the LED element 20 in response to the control signal Gsb supplied from the drive circuit 6. The driving transistor DRT is a transistor for controlling the amount of the driving current supplied to the anode of the LED element 20 in accordance with the video signal Vsg. The pixel switch SST is a transistor that controls a connection state (on/off state) between the pixel circuit and the video signal line VL in response to the control signal Gss. The drive circuit 6 includes a reset wiring switch RST for controlling input of a reset wiring potential. The output switch BCT, the driving transistor DRT, the pixel switch SST, and the reset wiring switch RST are, for example, thin film transistors. When the pixel switch SST is in the on state, the video signal Vsg is input to the pixel circuit from the video signal line VL.

The drive circuit 6 includes a shift register circuit, an output buffer circuit, and the like, which are not shown. The drive circuit 6 outputs a pulse based on the horizontal scanning start pulse transmitted from the control circuit 5 (see fig. 1), and outputs a control signal Gss, a control signal Gsb, and a control signal Gsr.

The plurality of scanning signal lines GL include scanning signal lines GLA and GLB and a reset line GLR. The plurality of scanning signal lines GL extend in the X direction, respectively. The scanning signal line GLA is connected to the gate of the output switch BCT. When the control signal Gsb is supplied to the scanning signal line GLA, the output switch BCT is turned on. The scanning signal line GLB is connected to a gate of the pixel switch SST. When the control signal Gss is supplied to the scanning signal line GLB, the pixel switch SST is turned on. The reset wiring GLR is connected between the output switch BCT and the drive transistor DRT, and is connected to a drain of the reset wiring switch RST. When a control signal Gsr as a reset wiring signal is supplied to the gate of the reset wiring switch RST, a reset wiring potential is supplied to the reset wiring GLR.

The pixel PIX has a holding capacitance Cs and an auxiliary capacitance Cad. The holding capacitance Cs and the auxiliary capacitance Cad are both capacitors. The holding capacitance Cs is connected between the gate of the drive transistor DRT and the terminal 30H. The auxiliary capacitor Cad is connected between the source of the output switch BCT and the terminal 30H. The auxiliary capacitor Cad is a capacitive element for adjusting the amount of light emission current, and as a modification, the auxiliary capacitor Cad may not be arranged.

< peripheral structure of LED element >

Next, a peripheral structure of the LED element disposed in the pixel PIX shown in fig. 1 will be described. Fig. 3 is an enlarged cross-sectional view showing an example of a peripheral structure of LED elements respectively arranged in a plurality of pixels of the display device shown in fig. 1. Fig. 4 is an enlarged cross-sectional view showing a modification of the LED element shown in fig. 3.

The array substrate SUB1 shown in fig. 3 is a substrate including a substrate 10 and a plurality of insulating layers stacked on the substrate 10. The plurality of insulating layers included in the array substrate SUB1 include an inorganic insulating layer 11, an organic insulating layer 12, and an organic insulating layer 13. The array substrate SUB1 includes various circuits provided in the pixel PIX described with reference to fig. 2. The substrate 10 has a surface 10f and a surface 10b opposite to the surface 10 f. The inorganic insulating layer 11, the organic insulating layer 12, and the organic insulating layer 13 are stacked on the surface 10f of the substrate 10.

In some cases, each of the inorganic insulating layer 11, the organic insulating layer 12, and the organic insulating layer 13 is a laminated film including a plurality of laminated insulating films. For example, semiconductor layers of thin film transistors constituting the output switch BCT, the drive transistor DRT, and the pixel switch SST shown in fig. 2 are formed in the inorganic insulating layer 11. A part of the plurality of inorganic insulating films constituting the inorganic insulating layer 11 functions as a base layer for forming a thin film transistor, and the other part functions as a gate insulating film of the thin film transistor.

As shown in fig. 3, the LED element 20 is mounted on the array substrate SUB1. The LED element 20 includes a surface 20f and a surface 20b opposite to the surface 20 f. The LED element 20 includes a plurality of (two in fig. 3) electrodes 20E arranged on the surface 20b. The plurality of electrodes 20E includes an anode 20EA and a cathode 20EK. Anode 20EA is connected to terminal 30H via conductive bonding material 40. The cathode 20EK is connected to the terminal 30L via the conductive bonding material 40. The conductive bonding material 40 is made of, for example, solder. Fig. 3 illustrates one LED element, but a plurality of LED elements are mounted in a matrix on the array substrate SUB1. The display device DSP1 displays an image by driving the plurality of LED elements 20 mounted on the array substrate SUB1. The light emitted from the LED element 20 is emitted from the surface 20f, for example.

Fig. 3 shows an example in which both the anode 20EA and the cathode 20EK are disposed on the surface 20b as an example of the LED element 20. However, there are many variations of the structure of the LED element 20. For example, in the case of the LED element 20M1 shown in fig. 4, the cathode 20EK is provided on the surface 20f, and the anode 20EA is provided on the surface 20b. When the LED element 20 shown in fig. 3 is replaced with the LED element 20M1 shown in fig. 4, a terminal 30L (see fig. 3) connected to the cathode 20EK is provided on the surface 20f of the LED element 20M 1.

< method for manufacturing LED display device >

Next, a method for manufacturing the display device DSP1 shown in fig. 1 will be described. Fig. 5 is an explanatory diagram illustrating a flow of a manufacturing process of the display device shown in fig. 1. In the flow illustrated in fig. 5, a method of sequentially mounting three types of LED elements for red, green, and blue, for example, on an array substrate will be described as an example. However, as a modification, there is also a method of mounting a plurality of types of LED elements 20 on an array substrate at a time using a holding substrate in which the plurality of types of LED elements are arranged in rows and columns, as described later.

< Process for preparing LED holding substrate and Process for preparing array substrate >

In the step of preparing the LED holding substrate shown in fig. 5, substrates SS1, SS2, and SS3 shown in fig. 6 are prepared. Fig. 6 is a plan view schematically showing a substrate prepared in the step of preparing the LED holding substrate shown in fig. 5. Substrate SS1, substrate SS2, and substrate SS3 each have an upper surface and a lower surface. The substrate SS1, the substrate SS2, and the substrate SS3 have a plurality of LED elements arranged in a matrix on one of the upper surface and the lower surface (the upper surface in the example shown in fig. 6).

Specifically, different types of LED elements are arranged on the substrate SS1, the substrate SS2, and the substrate SS3, respectively. In other words, each of the substrates SS1, SS2, and SS3 is an LED holding substrate that holds a plurality of LED elements. For example, the first inorganic light emitting element 21, which is one of a red LED element, a green LED element, and a blue LED element, is arranged on the upper surface SS1t of the substrate SS1. On the upper surface SS2t of the substrate SS2, the second inorganic light emitting element 22, which is a different LED element from the first inorganic light emitting element 21, is arranged among the red LED element, the green LED element, and the blue LED element. On the upper surface SS3t of the substrate SS3, the third inorganic light emitting element 23, which is an LED element different from the first inorganic light emitting element 21 and the second inorganic light emitting element, is arranged among the red LED element, the green LED element, and the blue LED element.

A plurality of first inorganic light emitting elements 21 are arranged in a matrix on the upper surface SS1t of the substrate SS1. The second and third inorganic light emitting elements 22 and 23 are not disposed on the upper surface SS1t of the substrate SS1. A plurality of second inorganic light emitting elements 22 are arranged in a matrix on upper surface SS2t of substrate SS2. The first and third inorganic light emitting elements 21 and 23 are not disposed on the upper surface SS2t of the substrate SS2. A plurality of third inorganic light emitting elements 23 are arranged in a matrix on the upper surface SS3t of the substrate SS3. The first and second phosphor elements 21 and 22 are not disposed on the upper surface SS3t of the substrate SS3. Each of the substrates SS1, SS2, and SS3 is a sapphire substrate, for example. Each of the first inorganic light emitting element 21, the second inorganic light emitting element 22, and the third inorganic light emitting element 23 is formed by, for example, laminating a metal film, an insulating film, a semiconductor film, and the like on a sapphire substrate.

In fig. 6, the planar shapes of the substrate SS1, the substrate SS2, and the substrate SS3 are illustrated as circles, but the planar shapes of the substrate SS1, the substrate SS2, and the substrate SS3 are not limited to circles, and various modifications such as quadrangles are possible.

In the present embodiment, an embodiment will be described in which all of the substrates SS1, SS2, and SS3 are prepared in advance before the step of mounting the first LED element, and the thicknesses of all types of substrates are measured in advance. In the case of this method, since the thicknesses of the first inorganic light emitting element 21, the second inorganic light emitting element 22, and the third inorganic light emitting element 23 are measured in advance, the mounting on the array substrate SUB1 can be started from the substrate including the LED element (inorganic light emitting element) 20 having the thinnest thickness, which is preferable. However, as a modification, all of the substrates SS1, SS2, and SS3 may not be prepared before the step of mounting the first LED element. For example, the substrate SS2 may be prepared and the thickness may be measured at least before the step of mounting the second LED element. Further, the substrate SS3 may be prepared and the respective thicknesses may be measured at least before the step of mounting the third LED element.

In the step of preparing the array substrate, an array substrate SUB1 shown in fig. 7 is prepared. Fig. 7 is a cross-sectional view schematically showing the array substrate SUB1 prepared in the step of preparing the array substrate shown in fig. 5. As shown in fig. 7, the array substrate SUB1 includes a surface SUBt and a surface SUBb opposite to the surface SUBt. The surface sutt is a mounting surface on which the plurality of LED elements 20 shown in fig. 6 are intended to be mounted.

The array substrate SUB1 has a plurality of terminals 30. The plurality of terminals 30 include a terminal (first terminal) 31 to be electrically connected to the first inorganic light emitting element 21 (see fig. 6). The plurality of terminals 30 include terminals (second terminals) 32 to be electrically connected to the second inorganic light emitting element 22 (see fig. 6). The plurality of terminals 30 includes a terminal (third terminal) 33 to be electrically connected to the third inorganic light emitting element 23 (see fig. 6). The terminals 31, 32, and 33 are arranged in rows and columns corresponding to the positions of the pixels PIX shown in fig. 1.

The step of preparing the array substrate may be performed before the step of measuring the thickness shown in fig. 5, and the order of the step of preparing the holding substrate is not limited. For example, the step of preparing the holding substrate and the step of preparing the array substrate may be performed simultaneously (in parallel).

< procedure for measuring thickness >

Next, a process of measuring the thickness shown in fig. 5 will be described. Fig. 8 is a cross-sectional view schematically showing an example of a measurement site in the step of measuring the thickness shown in fig. 5. Fig. 9 is an explanatory diagram illustrating an example of a thickness measuring method in the thickness measuring step shown in fig. 5.

In this step, data for controlling the press-in amount of pressing the substrate SS1, the substrate SS2, or the substrate SS3 shown in fig. 6 against the array substrate SUB1 shown in fig. 7 in each of the step of mounting the first LED element, the step of mounting the second LED element, and the step of mounting the third LED element, which will be described later, is collected. Therefore, in this step, the thickness is measured at each portion shown in fig. 8. In this step, the thickness TSUB of the array substrate SUB1 is measured. The thickness TSUB is the shortest distance between the surface (first surface) sutt and the surface (second surface) SUBb of the array substrate SUB1. As shown in fig. 7, the surface sutt is an upper surface of the organic insulating layer 13, an upper surface of the terminal 31, an upper surface of the terminal 32, or an upper surface of the terminal 33. As shown in fig. 3, the surface SUBb is the lower surface 10b of the substrate 10.

In this step, the thickness TSS1 of the substrate SS1 is measured. The thickness TSS1 of the substrate SS1 is the shortest distance between the upper surface SS1t and the lower surface SS1b of the substrate SS1. In this step, the thickness T21 of one or more first inorganic light-emitting elements 21 among the plurality of first inorganic light-emitting elements 21 arranged on the substrate SS1 is measured. The thickness T21 of the first inorganic light emitting element 21 is the shortest distance between the surface 20f and the surface 20b or the shortest distance between the surface 20f and the surface of the electrode 20E facing the substrate SUB1 shown in fig. 3. However, the shortest distance between the surface 20b of the first phosphor element 21 or the surface of the electrode 20E facing the substrate SUB1 and the lower surface SS1b of the substrate SS1 may be measured, and the difference between the measurement result and the thickness TSS1 of the substrate SS1 may be regarded as the thickness T21 of the first phosphor element 21.

In this step, the thickness TSS2 of the substrate SS2 is measured. Thickness TSS2 of substrate SS2 is the shortest distance between upper surface SS2t and lower surface SS2b of substrate SS2. In this step, the thickness T22 of one or more second inorganic light emitting elements 22 among the plurality of second inorganic light emitting elements 22 arranged on the substrate SS2 is measured. The thickness T22 of the second phosphor element 22 is the shortest distance between the surface 20f and the surface 20b shown in fig. 3, or the shortest distance between the surface 20f and the surface of the electrode 20E facing the substrate SUB1. However, the shortest distance between the surface 20b of the second inorganic light emitting element 22 or the surface of the electrode 20E facing the substrate SUB1 and the lower surface SS2b of the substrate SS2 may be measured, and the difference between the measurement result and the thickness TSS2 of the substrate SS2 may be regarded as the thickness T22 of the second inorganic light emitting element 22.

In this step, the thickness TSS3 of the substrate SS3 is measured. Thickness TSS3 of substrate SS3 is the shortest distance between upper surface SS3t and lower surface SS3b of substrate SS3. In this step, the thickness T23 of one or more third inorganic light-emitting elements 23 among the plurality of third inorganic light-emitting elements 23 arranged on the substrate SS3 is measured. The thickness T23 of the third phosphor element 23 is the shortest distance between the surface 20f and the surface 20b shown in fig. 3, or the shortest distance between the surface 20f and the surface of the electrode 20E facing the substrate SUB1. However, the shortest distance between the surface 20b of the third inorganic light emitting element 23 or the surface of the electrode 20E facing the substrate SUB1 and the lower surface SS3b of the substrate SS3 may be measured, and the difference between the measurement result and the thickness TSS3 of the substrate SS3 may be regarded as the thickness T23 of the third inorganic light emitting element 23.

In this step, the thickness TSS1, the thickness TSS2, and the thickness TSS3 may be measured at a plurality of positions. In this case, since the reliability of the measurement result is improved, the pressing force can be precisely controlled in each of the step of mounting the first LED element, the step of mounting the second LED element, and the step of mounting the third LED element, which will be described later. However, since the plurality of LED elements 20 formed on one sapphire substrate are formed together at the same timing, the plurality of LED elements 20 formed on the same sapphire substrate are less likely to have different thicknesses. Therefore, in consideration of the work efficiency, it is preferable to measure the thickness of one of the plurality of LED elements 20 (for example, the thickness T21 of one of the plurality of first inorganic light emitting elements 21, the thickness T22 of one of the plurality of second inorganic light emitting elements 22, and the thickness T23 of one of the plurality of third inorganic light emitting elements 23 of the plurality of second inorganic light emitting elements 22).

The method for measuring the thickness in this step is not particularly limited. However, the thickness of the LED element 20 is about 100 μm to 200 μm. Therefore, the thickness in this step needs to be measured with accuracy in the order of μm. This is because, in the step of mounting the first LED element, the step of mounting the second LED element, and the step of mounting the third LED element, which will be described later, when the thickness of each measurement portion shown in fig. 8 varies by about several μm, it is necessary to adjust the pressing force.

As a method capable of measuring a thickness on the order of μm and measuring the thickness efficiently, a method of measuring a workpiece (an object to be measured) in a state of being sandwiched between two sensor heads can be exemplified. In the example shown in fig. 9, the workpiece 51 is disposed between the sensor heads 50A and 50B arranged at positions facing each other. The work 51 corresponds to the array substrate SUB1, the substrate SS2, and the substrate SS3 shown in fig. 8. The workpiece 51 is irradiated with laser light 52 from the sensor heads 50A and 50B, respectively. By detecting the light reflected by the surface 51t of the workpiece 51 by the sensor head 50A and the light reflected by the surface 51B of the workpiece 51 by the sensor head 50B, the distance 53A from the sensor head 50A to the surface 51t of the workpiece 51 and the distance 53B from the sensor head 50B to the surface 51B of the workpiece 51 are measured. Since the separation distance 53C between the sensor head 50A and the sensor head 50B is set in advance, a value obtained by subtracting the values of the distance 53A and the distance 53B from the separation distance 53C can be calculated as the thickness T51 of the workpiece 51.

However, as described above, the thickness measurement method may be a method capable of measuring a thickness on the order of μm, and various modifications other than the method shown in fig. 9 may be applied. For example, when the workpiece 51 is made of a material having a property of transmitting the laser beam 52, there is a method of measuring light reflected by the surface 51t and the surface 51b of the workpiece 51, respectively, and calculating a measured thickness from an interference difference of the reflected light. In addition, for example, in the case of the above method, the laser light 52 needs to be reflected by the surface of the workpiece 51. Therefore, in some cases, it is preferable to adopt another method when the workpiece 51 is a member that is difficult to reflect the laser beam 52. As another method, for example, a measurement method using ultrasonic waves can be exemplified.

< Process of mounting first LED element >

Next, a process of mounting the first LED element shown in fig. 5 will be described. Fig. 10 is a cross-sectional view schematically showing a state in which the substrate on which the first inorganic light emitting elements are arranged is pressed against the array substrate in the step of mounting the first LED elements shown in fig. 5.

In the step of mounting the first LED elements, in a state where the substrate SS1 held on the table 61 and the array substrate SUB1 held on the table 62 are opposed to each other, each of the plurality of first inorganic light emitting elements 21 is pressed against the array substrate SUB1, whereby the plurality of terminals 31 (see fig. 7) of the array substrate SUB1 and the plurality of first inorganic light emitting elements 21 are electrically connected.

The table 61 is a member capable of holding the substrate SS1. The lower surface SS1b of the substrate SS1 is held by the holding surface 61h of the table 61. The table 62 is a member capable of holding the array substrate SUB1. The surface SUBb of the array substrate SUB1 is held by the holding surface 62h of the table 62. Examples of a method for holding the substrate SS1 by the table 61 and a method for holding the array substrate SUB1 by the table 62 include a method of suction-holding, a method of fixing the peripheral edge portion of the substrate SS1 or the array substrate SUB1 by a fixing jig not shown, and the like.

The holding surface 61h of the table 61 and the holding surface 62h of the table 62 face each other. Therefore, in a state where the lower surface SS1b of the substrate SS1 is held by the holding surface 61h and the surface SUBb of the array substrate SUB1 is held by the holding surface 62h, the upper surface SS1t of the substrate SS1 and the surface SUBt of the array substrate SUB1 face each other as shown in fig. 10. The table 61 and the table 62 each have a mechanism capable of moving them in the planar direction (X-Y planar direction) independently of each other. In this step, at least one of the stage 61 and the stage 62 is moved in the X-Y plane direction to perform precise alignment so that the electrodes 20E (see fig. 3) provided in the plurality of first inorganic light emitting elements 21 face the terminals 31 (see fig. 3) of the array substrate SUB1, respectively. At this time, the electrode 20E shown in fig. 3 has already been joined to the conductive joining member 40. Therefore, when the positioning is performed in the direction along the X-Y plane, the terminal 31 is in a state of facing the conductive bonding material 40 bonded to the electrode 20E of the first inorganic light emitting element 21.

When the stage 61 and the stage 62 are brought close to each other in the state where the alignment is performed in the direction along the X-Y plane, each of the plurality of first phosphor elements 21 arranged on the upper surface SS1t of the substrate SS1 is brought close to the array substrate SUB1. At this time, each of the plurality of conductive bonding members 40 shown in fig. 3 is in contact with the terminal 31. In this state, since the conductive bonding material 40 is bonded to the terminal 31 by performing, for example, a reflow process (heat treatment), the electrode 20E of the first inorganic light emitting element 21 and the terminal 31 are electrically connected via the conductive bonding material 40.

Here, in order to connect the plurality of conductive bonding materials 40 and the plurality of terminals 31, respectively, it is necessary to perform a reflow soldering process in a state where an appropriate load is applied to the contact surfaces of the conductive bonding materials 40 and the terminals 31. For example, if the pressing force for pressing the first inorganic light emitting element 21 against the array substrate SUB1 is insufficient, the conductive bonding material 40 and the terminal 31 are not well bonded, resulting in a decrease in electrical connection reliability. On the other hand, if the pressing force for pressing the first inorganic light emitting element 21 against the array substrate SUB1 is too large, the first inorganic light emitting element 21 itself or members around the conductive bonding material 40 may be damaged. The LED element 20 shown in fig. 3 is a micro LED element and has a small outer size. Therefore, even when the positional relationship between the conductive bonding material 40 and the terminal 31 is deviated by about several μm in the Z direction shown in fig. 3, the above problem may become significant. In particular, there is a case where an error occurs in the thickness of the LED element due to a difference in the manufacturing conditions of the LED element 20. Therefore, in the case of manufacturing lot change or the like, there is a case where the thickness of the LED element 20 deviates from the design value, for example, in the order of μm.

In the case of the present embodiment, as described with reference to fig. 5 to 9, the step of measuring the thickness is performed before the step of mounting the first LED element, and the thickness TSUB of the array substrate SUB1, the thickness TSS1 of the substrate SS1, and the thickness T21 of the first inorganic light emitting element 21 shown in fig. 8 are measured. In the step of mounting the first LED elements in the present embodiment, the press-in amount by which each of the plurality of first inorganic light emitting elements 21 is pressed against the array substrate SUB1 is controlled based on the result of measurement in the step of measuring the thickness. For example, when the total value of the measurement results of the thickness TSUB of the array substrate SUB1, the thickness TSS1 of the substrate SS1, and the thickness T21 of the first phosphor 21 is smaller than the design value, the final separation distance after the stage 61 and the stage 62 approach each other is controlled to be smaller than a predetermined value. That is, the press-fitting amount of the first inorganic light emitting element 21 against the array substrate SUB1 is reduced. The degree of reduction in the press-in amount is defined based on the difference between the total value of the measurement results of the thickness TSUB of the array substrate SUB1, the thickness TSS1 of the substrate SS1, and the thickness T21 of the first inorganic light-emitting element 21 and the design value. On the other hand, when the total value of the measurement results of the thickness TSUB of the array substrate SUB1, the thickness TSS1 of the substrate SS1, and the thickness T21 of the first inorganic light emitting element 21 is larger than the design value, the final separation distance after the stage 61 and the stage 62 approach each other is controlled to be larger than a preset value. That is, the press-in amount of pressing the first inorganic light emitting element 21 against the array substrate SUB1 is increased. The degree of increasing the press-in amount is determined based on the difference between the total value of the measurement results of the thickness TSUB of the array substrate SUB1, the thickness TSS1 of the substrate SS1, and the thickness T21 of the first inorganic light emitting element 21 and the design value. This allows the reflow soldering process to be performed in a state where an appropriate load is applied to the contact surface between the conductive bonding material 40 and the terminal 31 shown in fig. 3. As a result, the reliability of the electrical connection between the electrode 20E of the first inorganic light emitting element 21 and the terminal 31 via the conductive bonding material 40 can be improved.

However, in the example shown in fig. 10, the embodiment in which the pressing force is applied by pressing the table 61 in the direction of the table 62 is illustrated, but there are various modifications of the method for applying the pressing force. For example, there are a method of pushing the table 62 upward toward the table 61, a method of moving each of the table 61 and the table 62 in the Z direction, and the like.

< Process of peeling off the first holding substrate >

Next, a process of peeling off the first holding substrate shown in fig. 5 will be described. Fig. 11 is a cross-sectional view schematically showing a state where the holding substrate is peeled from the plurality of first inorganic light emitting elements in the step of peeling the first holding substrate shown in fig. 5. In the step of peeling the first holding substrate, as shown in fig. 11, after the step of mounting the first LED elements, the substrate SS1 is peeled from the plurality of first inorganic light emitting elements 21.

As a method of peeling off the bonding interface between the upper surface SS1t of the substrate SS1 as the holding substrate and the plurality of first inorganic light emitting elements 21, a technique called laser peeling, for example, can be used. In the case of using a technique called laser lift-off, for example, an ultraviolet laser is irradiated from the lower surface SS1b side of the substrate SS1 to the adhesion interface between the upper surface SS1t of the substrate SS1 and the plurality of first phosphor elements 21. A gallium nitride layer is formed on the surface 20b (see fig. 3) of the first inorganic light-emitting element 21. When the surface 20b of the first phosphor element 21 is irradiated with the ultraviolet laser, the surface layer (a part on the surface 20b side) of the gallium nitride layer is modified, and the substrate SS1 and the first phosphor element 21 can be peeled off.

Through this step, a structure in which a plurality of first inorganic light emitting elements 21 are mounted on the array substrate SUB1 is obtained.

< Process of mounting second LED element >

Next, a process of mounting the second LED element shown in fig. 5 will be described. Fig. 12 is a cross-sectional view schematically showing a state in which the substrate on which the second inorganic light emitting elements are arranged is pressed against the array substrate in the step of mounting the second LED elements shown in fig. 5.

In the step of mounting the second LED elements, in a state where the substrate SS2 held on the stage 61 and the array substrate SUB1 held on the stage 62 are opposed to each other, each of the plurality of second inorganic light emitting elements 22 is pressed against the array substrate SUB1, whereby the plurality of terminals 32 (see fig. 7) of the array substrate SUB1 and the plurality of second inorganic light emitting elements 22 are electrically connected.

The lower surface SS2b of the substrate SS2 is held by the holding surface 61h of the table 61. The table 62 is a member capable of holding the array substrate SUB1. The array substrate SUB1 on which the plurality of first inorganic light emitting elements 21 are already mounted holds the surface SUBb side on the holding surface 62h of the table 62. As described above, there are various methods for holding the substrate SS2 by the table 61 and for holding the array substrate SUB1 by the table 62.

The holding surface 61h of the table 61 and the holding surface 62h of the table 62 face each other. Therefore, in a state where the lower surface SS2b of the substrate SS2 is held by the holding surface 61h and the surface SUBb of the array substrate SUB1 is held by the holding surface 62h, the upper surface SS2t of the substrate SS2 and the surface SUBt of the array substrate SUB1 face each other as shown in fig. 12. As described above, each of the tables 61 and 62 includes a mechanism capable of moving the table in the planar direction (X-Y planar direction) independently of the other. In this step, at least one of the stages 61 and 62 is moved in the X-Y plane direction to perform precise alignment so that each of the electrodes 20E (see fig. 3) of the plurality of second inorganic light emitting elements 22 faces the terminal 32 (see fig. 3) of the array substrate SUB1. At this time, the electrode 20E shown in fig. 3 has been joined to the conductive bonding member 40. Therefore, when the positioning is performed in the direction along the X-Y plane, the terminal 32 is in a state of facing the conductive bonding material 40 bonded to the electrode 20E of the second inorganic light emitting element 22.

When the stage 61 and the stage 62 are brought close to each other in the state where the alignment is performed in the direction along the X-Y plane, each of the plurality of second phosphor elements 22 arranged on the upper surface SS2t of the substrate SS2 is brought close to the array substrate SUB1. At this time, each of the plurality of conductive bonding members 40 shown in fig. 3 is in contact with the terminal 32. In this state, for example, reflow (heat treatment) is performed to bond the conductive bonding material 40 to the terminal 32, and thus the electrode 20E of the second inorganic light emitting element 22 and the terminal 32 are electrically connected via the conductive bonding material 40.

In the case of this embodiment, a step of measuring the thickness is performed before the step of mounting the second LED element, and the thickness TSUB of the array substrate SUB1, the thickness TSS2 of the substrate SS2, and the thickness T22 of the second inorganic light emitting element 22 shown in fig. 8 are measured. In the step of mounting the second LED elements in the present embodiment, the press-in amount by which each of the plurality of second inorganic light emitting elements 22 is pressed against the array substrate SUB is controlled based on the result of measurement in the step of measuring the thickness. For example, when the total value of the measurement results of the thickness TSUB of the array substrate SUB1, the thickness TSS2 of the substrate SS2, and the thickness T22 of the second inorganic light emitting element 22 is smaller than the design value, the final separation distance after the stage 61 and the stage 62 are brought close to each other is controlled to be smaller than a preset value. That is, the press-fitting amount by which the second inorganic light emitting element 22 is pressed against the array substrate SUB1 is reduced. The degree of reduction in the press-in amount is defined based on the difference between the total value of the measurement results of the thickness TSUB of the array substrate SUB1, the thickness TSS2 of the substrate SS2, and the thickness T22 of the first inorganic light-emitting element 22 and the design value. On the other hand, when the total value of the measurement results of the thickness TSUB of the array substrate SUB1, the thickness TSS2 of the substrate SS2, and the thickness T22 of the second inorganic light emitting element 22 is larger than the design value, the final separation distance after the stage 61 and the stage 62 are brought close to each other is controlled to be larger than a preset value. That is, the press-in amount of the second inorganic light emitting element 22 against the array substrate SUB1 is increased. The degree of increasing the press-in amount is determined based on the difference between the total value of the measurement results of the thickness TSUB of the array substrate SUB1, the thickness TSS2 of the substrate SS2, and the thickness T22 of the second inorganic light emitting element 22 and the design value. This allows the reflow soldering process to be performed with an appropriate load applied to the contact surface between the conductive bonding material 40 and the terminal 32 as shown in fig. 3. As a result, the reliability of the electrical connection between the electrode 20E of the second inorganic light-emitting element 22 and the terminal 32 via the conductive bonding material 40 can be improved.

Further, the thickness T21 (see fig. 8) of each of the plurality of first inorganic light emitting elements 21 is preferably equal to or less than the thickness T22 (see fig. 8) of each of the plurality of second inorganic light emitting elements 22. The step of mounting the second LED elements is performed in a state where a plurality of first inorganic light emitting elements 21 are already mounted on the array substrate SUB1. Therefore, in this step, it is particularly preferable that the thickness T21 be smaller than the thickness T22 in order to suppress damage to the plurality of first inorganic light emitting elements 21 interposed between the substrate SS2 and the array substrate SUB1.

< Process of peeling off the second holding substrate >

Next, a step of peeling off the second holding substrate shown in fig. 5 will be described. Fig. 13 is a cross-sectional view showing a state where the holding substrate is peeled off from the plurality of second inorganic light emitting elements in the step of peeling off the second holding substrate shown in fig. 5. In the step of peeling the second holding substrate, as shown in fig. 13, after the step of mounting the second LED elements, the substrate SS2 and the plurality of second inorganic light emitting elements 22 are peeled. As a method of peeling the bonding interface between the upper surface SS2t of the substrate SS2 as the holding substrate and the plurality of second inorganic light emitting elements 22, a technique called laser peeling, for example, can be used in the same manner as the step of peeling the first holding substrate. By this step, a structure in which the plurality of first inorganic light emitting elements 21 and the plurality of second inorganic light emitting elements 22 are mounted on the array substrate SUB1 can be obtained.

< Process of mounting third LED element >

Next, a process of mounting the third LED element shown in fig. 5 will be described. Fig. 14 is a cross-sectional view schematically showing a state in which the substrate on which the third inorganic light emitting elements are arranged is pressed against the array substrate in the step of mounting the third LED elements shown in fig. 5.

In the step of mounting the third LED elements, each of the plurality of third inorganic light emitting elements 23 is pressed against the array substrate SUB1 in a state where the substrate SS3 held on the stage 61 and the array substrate SUB1 held on the stage 62 are opposed to each other, whereby the plurality of terminals 33 (see fig. 7) of the array substrate SUB1 and the plurality of third inorganic light emitting elements 23 are electrically connected.

The lower surface SS3b of the substrate SS3 is held by the holding surface 61h of the table 61. The table 62 is a member capable of holding the array substrate SUB1. The array substrate SUB1 on which the plurality of first inorganic light emitting elements 21 and the plurality of second inorganic light emitting elements 22 are already mounted holds the surface SUBb side on the holding surface 62h of the table 62. As described above, there are various methods for holding the substrate SS3 by the table 61 and for holding the array substrate SUB1 by the table 62.

The holding surface 61h of the table 61 and the holding surface 62h of the table 62 face each other. Therefore, in a state where the lower surface SS3b of the substrate SS3 is held by the holding surface 61h and the surface SUBb of the array substrate SUB1 is held by the holding surface 62h, the upper surface SS3t of the substrate SS3 and the surface SUBt of the array substrate SUB1 face each other as shown in fig. 14. As described above, each of the tables 61 and 62 includes a mechanism capable of moving the table independently in the planar direction (X-Y planar direction). In this step, at least one of the stages 61 and 62 is moved in the X-Y plane direction so as to be precisely aligned such that each of the electrodes 20E (see fig. 3) of the plurality of third inorganic light emitting elements 23 faces the terminal 33 (see fig. 3) of the array substrate SUB1. At this time, the electrode 20E shown in fig. 3 has already been joined to the conductive joining member 40. Therefore, when the positioning is performed in the direction along the X-Y plane, the terminal 33 is in a state of facing the conductive bonding material 40 bonded to the electrode 20E of the third inorganic light emitting element 23.

When the stage 61 and the stage 62 are brought close to each other in the state where the alignment is performed in the direction along the X-Y plane, each of the plurality of third phosphor elements 23 arranged on the upper surface SS3t of the substrate SS3 is brought close to the array substrate SUB1. At this time, each of the plurality of conductive bonding members 40 shown in fig. 3 is in contact with the terminal 33. In this state, for example, reflow (heat treatment) is performed to bond the conductive bonding material 40 to the terminal 33, and thus the electrode 20E of the third inorganic light emitting element 23 and the terminal 33 are electrically connected via the conductive bonding material 40.

In the case of this embodiment, a step of measuring the thickness is performed before the step of mounting the third LED element, and the thickness TSUB of the array substrate SUB1, the thickness TSS3 of the substrate SS3, and the thickness T23 of the third inorganic light emitting element 23 shown in fig. 8 are measured. In the step of mounting the third LED elements in the present embodiment, the press-in amount by which each of the plurality of third inorganic light emitting elements 23 is pressed against the array substrate SUB is controlled based on the result of measurement in the step of measuring the thickness. For example, when the total value of the measurement results of the thickness TSUB of the array substrate SUB1, the thickness TSS3 of the substrate SS3, and the thickness T23 of the third inorganic light emitting element 23 is smaller than the design value, the final separation distance after the stage 61 and the stage 62 approach each other is controlled to be smaller than a preset value. That is, the press-fitting amount by which the third inorganic light emitting element 23 is pressed against the array substrate SUB1 is reduced. The degree of reduction in the press-in amount is defined based on the difference between the total value of the measurement results of the thickness TSUB of the array substrate SUB1, the thickness TSS3 of the substrate SS3, and the thickness T23 of the first inorganic light-emitting element 23 and the design value. On the other hand, when the total value of the measurement results of the thickness TSUB of the array substrate SUB1, the thickness TSS3 of the substrate SS3, and the thickness T23 of the third phosphor element 23 is larger than the design value, the final separation distance after the stage 61 and the stage 62 approach each other is controlled to be larger than a predetermined value. That is, the press-in amount of the third inorganic light emitting element 23 pressed against the array substrate SUB1 is increased. The degree of increasing the press-in amount is determined based on the difference between the total value of the measurement results of the thickness TSUB of the array substrate SUB1, the thickness TSS3 of the substrate SS3, and the thickness T23 of the third inorganic light emitting element 23 and the design value. This allows the reflow soldering process to be performed in a state where an appropriate load is applied to the contact surface between the conductive joining material 40 and the terminal 33 as shown in fig. 3. As a result, the reliability of the electrical connection between the electrode 20E of the third inorganic light-emitting element 23 and the terminal 33 via the conductive bonding material 40 can be improved.

Further, the thickness T21 (see fig. 8) of each of the plurality of first inorganic light emitting elements 21 is preferably equal to or less than the thickness T23 (see fig. 8) of each of the plurality of third inorganic light emitting elements 23. Further, the thickness T22 (see fig. 8) of each of the plurality of second inorganic light emitting elements 22 is preferably equal to or less than the thickness T23 of each of the plurality of third inorganic light emitting elements 23. The step of mounting the third LED element is performed in a state where the plurality of first inorganic light emitting elements 21 and the plurality of second inorganic light emitting elements 22 have already been mounted on the array substrate SUB1. Therefore, in this step, from the viewpoint of suppressing damage to the plurality of first inorganic light emitting elements 21 and the plurality of second inorganic light emitting elements 22 sandwiched between the substrate SS3 and the array substrate SUB1, it is particularly preferable that both the thickness T21 and the thickness T22 are smaller than the thickness T23.

< Process of peeling off third holding substrate >

Next, a step of peeling off the third holding substrate shown in fig. 5 will be described. Fig. 15 is a cross-sectional view schematically showing a state where the holding substrate is peeled from the plurality of third inorganic light emitting elements in the step of peeling the third holding substrate shown in fig. 5. In the step of peeling the third holding substrate, as shown in fig. 13, the substrate SS3 is peeled from the plurality of third inorganic light emitting elements 23 after the step of mounting the third LED elements. A method of peeling off the bonding interface between the upper surface SS3t of the substrate SS3 as the holding substrate and the plurality of third inorganic light emitting elements 23 can use a technique called laser peeling, for example, as in the above-described step of peeling off the first holding substrate. Through this step, a structure in which the plurality of first inorganic light emitting elements 21, the plurality of second inorganic light emitting elements 22, and the plurality of third inorganic light emitting elements 23 are mounted on the array substrate SUB1 is obtained. After this step, a protective film or the like for protecting the plurality of LED elements 20 is formed as necessary, thereby obtaining the display device shown in fig. 1.

As described above, according to the present embodiment, the pressing force at the time of mounting can be precisely controlled by measuring the thickness TSUB of the array substrate SUB1, the thicknesses (the thicknesses TSS1, TSS2, and TSS 3) of the holding substrates (the substrates SS1, SS2, and SS 3), and the thicknesses (the thicknesses T21, T22, and T23) of the LED elements 20 shown in fig. 8 before the plurality of LED elements (inorganic light emitting elements) 20 are mounted on the array substrate SUB1. As a result, the reliability of electrical connection between the LED element 20 and the array substrate SUB1 can be improved.

In the example shown in fig. 5, an embodiment in which three types of LED elements are sequentially mounted has been described, but the types of LED elements to be mounted are not limited to three types. For example, when one kind of LED elements is required to be mounted together, the step of mounting the second LED elements to the step of peeling the third holding substrate shown in fig. 5 can be omitted. In addition, for example, in the case of a method for manufacturing a display device of a type in which two types of LED elements are mounted, the step of mounting the third LED element to the step of peeling the third holding substrate shown in fig. 5 can be omitted. In the case of a method for manufacturing a display device of a type in which four or more LED elements are mounted, the method is obtained by repeating an LED element mounting step and a holding substrate peeling step for mounting LED elements different from the first to third LED elements after the third holding substrate peeling step shown in fig. 5.

< modification of holding substrate >

As another modification to fig. 5, a plurality of types (for example, three types) of LED elements may be collectively mounted on the array substrate SUB1. This modification is explained below. Fig. 16 is a cross-sectional view schematically showing a state before mounting on an array substrate using a holding substrate that holds a plurality of types of LED elements simultaneously, according to the modification of fig. 10.

The substrate SS4 shown in fig. 16 has an upper surface SS4t and a lower surface SS4b. The LED elements 20 including the first inorganic light emitting elements 21, the second inorganic light emitting elements 22, and the second inorganic light emitting elements 22 are arranged in a matrix on the upper surface SS4t of the substrate SS 4. The substrate SS4 is only a support substrate and not a substrate for manufacturing the LED element 20, and thus a sapphire substrate is not required. For example, a substrate such as a glass substrate can be used. The plurality of LED elements 20 are adhesively fixed to the upper surface SS4t of the substrate SS4 via an adhesive layer not shown.

As a method of arranging the plurality of LED elements 20 on the upper surface SS4t of the substrate SS4, for example, a method of sequentially mounting the first inorganic light emitting element 21, the second inorganic light emitting element 22, and the third inorganic light emitting element 23 on the array substrate SUB1 shown in fig. 8 can be applied. When LED element 20 is bonded and fixed to substrate SS4, the step of measuring the thickness can be omitted because electrical connection and the like are not necessary. However, a step of measuring the thickness is required before the LED mounting step of pressing the substrate SS4 against the array substrate SUB1.

In the case of the present modification, in the step of measuring the thickness, it is preferable to measure the thickness for the plurality of LED elements 20 so that the LED element 20 having the thinnest thickness and the LED element 20 having the thickest thickness among the plurality of LED elements 20 can be detected. By measuring the LED element 20 with the thinnest thickness and the LED element 20 with the thickest thickness, the margin allowed for the pressing force value can be calculated in the LED element mounting process.

In the case of this modification, since a plurality of types of LED elements 20 are collectively mounted on the array substrate SUB1, the time required for the LED element mounting step can be shortened as compared with the example shown in fig. 5. However, the LED elements 20 of different types may have different thicknesses depending on the type, and the manufacturing method illustrated in fig. 5 is preferable from the viewpoint of improving the electrical connection reliability between the LED elements 20 and the terminals 30 (see fig. 3).

While the embodiments and the representative modifications have been described above, the above-described technology can be applied to various modifications other than the illustrated modifications. For example, the above modifications may be combined with each other.

Those skilled in the art can conceive of various modifications and adaptations within the scope of the idea of the present invention, and it is understood that these modifications and adaptations also fall within the scope of the present invention. For example, a person skilled in the art can add, delete, or change the design of components, or add, omit, or change the conditions of the process as appropriate to each of the above embodiments, and the scope of the present invention is included as long as the gist of the present invention is achieved.

Industrial applicability

The present invention can be applied to a display device and an electronic apparatus incorporating the display device.

Claims (4)

1. A method for manufacturing a display device, comprising the steps of:

(a) Preparing a first substrate on which a plurality of first inorganic light emitting elements are arranged in rows and columns and an array substrate on which a plurality of first terminals are formed;

(b) Measuring each of the thickness of the first substrate, the thickness of one or more first inorganic light emitting elements among the plurality of first inorganic light emitting elements, and the thickness of the array substrate;

(c) A step of electrically connecting the plurality of first terminals of the array substrate and the plurality of first inorganic light emitting elements by pressing each of the plurality of first inorganic light emitting elements against the array substrate in a state where the first substrate held on the first stage and the array substrate held on the second stage are opposed to each other; and

(d) A step of separating the first substrate from the plurality of first inorganic light emitting elements after the step (c),

wherein, in the step (c), the press-in amount by which each of the plurality of first inorganic light emitting elements is pressed against the array substrate is controlled based on the result measured in the step (b).

2. The method for manufacturing a display device according to claim 1,

a plurality of second terminals are further formed on the array substrate prepared in the step (a), and the manufacturing method includes:

(e) Preparing a second substrate on which a plurality of second inorganic light emitting elements are arranged in a matrix;

(f) Measuring each of the thickness of one or more second inorganic light emitting elements among the plurality of second inorganic light emitting elements and the thickness of the second substrate;

(g) After the steps (d), (e) and (f), pressing each of the plurality of second inorganic light emitting elements against the array substrate in a state where the second substrate held on the first stage and the array substrate held on the second stage are opposed to each other, thereby electrically connecting the plurality of second terminals of the array substrate and the plurality of second inorganic light emitting elements; and

(h) A step of peeling the second substrate from the plurality of second inorganic light emitting elements after the step (g),

wherein in the step (g), the press-in amount by which each of the plurality of second inorganic light emitting elements is pressed against the array substrate is controlled based on the results measured in the steps (b) and (f).

3. The method of manufacturing a display device according to claim 2, wherein a plurality of third terminals are further formed on the array substrate prepared in the step (a), the method comprising:

(i) Preparing a third substrate on which a plurality of third inorganic light emitting elements are arranged in a matrix;

(k) Measuring each of a thickness of one or more third inorganic light emitting elements among the plurality of third inorganic light emitting elements and a thickness of the third substrate;

(m) after the step (h), the step (i), and the step (k), pressing each of the plurality of third inorganic light emitting elements against the array substrate in a state where the third substrate held on the first stage and the array substrate held on the second stage are opposed to each other, thereby electrically connecting the plurality of third terminals of the array substrate and the plurality of third inorganic light emitting elements; and

(n) a step of separating the third substrate from the plurality of third inorganic light emitting elements after the step (m),

wherein in the step (m), the press-in amount by which each of the plurality of third inorganic light emitting elements is pressed against the array substrate is controlled based on the results measured in the steps (b) and (k).

4. The method for manufacturing a display device according to claim 3, wherein each of the step (e), the step (f), the step (i), and the step (k) is performed before the step (c),

the thickness of the first inorganic light emitting element measured in the step (b) is thinner than each of the thickness of the second inorganic light emitting element measured in the step (f) and the thickness of the third inorganic light emitting element measured in the step (k),

the thickness of the second inorganic light emitting element measured in the step (f) is thinner than each of the thicknesses of the third inorganic light emitting elements measured in the step (k).

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