WO2023226457A1

WO2023226457A1 - Display panel, and light-emitting element and back plate for use in display panel

Info

Publication number: WO2023226457A1
Application number: PCT/CN2023/072610
Authority: WO
Inventors: 马刚
Original assignee: 厦门市芯颖显示科技有限公司
Priority date: 2022-05-26
Filing date: 2023-01-17
Publication date: 2023-11-30
Also published as: CN218123408U

Abstract

The present application provides a display panel, and a light-emitting element and a back plate for use in the display panel. A first pad and a second pad used as a repair pad are formed on the back plate; the first pad comprises a first adhesive layer and a first bonding layer; the second pad comprises a second adhesive layer and a second bonding layer; the first bonding layer and the second bonding layer are both have a multi-layer structure; the multi-layer structure comprises a plurality of pure metal layers, and the bonding temperature of the first bonding layer is higher than the bonding temperature of the second bonding layer. The plurality of pure metal layers are formed on the first pad and the second pad by means of a vapor deposition method, so that the purity of each pure metal layer is ensured, thus facilitating subsequent formation of alloys having different melting points. When the second pad is heated to solder LED chips for repair, a first alloy on the first pad does not melt, so that the stability of LED chips on the first pad is ensured, and batch deviation of the LED chips is prevented, thereby ensuring the yield of batch transfer of the LED chips.

Description

A display panel and a light-emitting element and a backplane used for the display panel

Technical field

The present application relates to the technical field of semiconductor devices and devices, and in particular to a display panel, a light-emitting element and a backplane used for the display panel.

Background technique

LED has attracted special attention in the lighting and display fields due to its high luminous efficiency, long service life, safety, reliability, environmental protection and energy saving. When LED is used for display, a huge amount of LED chips need to be transferred. The number of transferred LED chips is in the millions or even tens of millions. To achieve a mass production-level transfer and bonding yield of 99.9999%, repairable technology after bonding is one of them. key. The current metal bonding process deposits a low melting point solder alloy and then heats the solder thermally to form a metallurgically bonded connection point after bonding.

In the Micro-LED display backplane, the gap between LED chips is very small, less than 100 μm. After primary bonding, if transfer failure or chip failure is found, secondary repair bonding is required. During the sexual bonding process, the newly transferred LED chip (used for repair) needs to be repaired metal bonded.

In the existing technology, the same solder is deposited on the pads for primary bonding and repair bonding in the backplane, or the same solder is deposited on the LED chips (primary bonding chips and repair chips) used on the same backplane. solder. In this way, during the restorative bonding process, the newly transferred LED chip needs to be bonded. The bonding temperature will cause the bonding points of the once-bonded LED chip to be remelted or partially melted, resulting in the LED chip being damaged. Mass migration or bonding point damage. If effective repair cannot be carried out, it is very difficult to achieve mass production yield (99.9999%).

technical problem

Based on the above defects, it is necessary to provide a repair technology that can ensure the yield of LED chip transfer.

Technical solutions

In view of the shortcomings in the transfer and repair of LED chips in display panels in the prior art, this application provides a display panel, a light-emitting element and a backplane used for the display panel. A first bonding layer and a second bonding layer are respectively formed on the first bonding pad of the backplane and the second bonding pad for repair. The first bonding layer and the second bonding layer include multiple pure metal layers. , and the bonding temperature of the first bonding layer is higher than the bonding temperature of the second bonding layer. This ensures that during the bonding process of the repair LED chips after the primary bonding is completed, heating the second bonding layer will not affect the bonded LEDs, and the LED batch offset will not occur, thus ensuring that the LED Chip transfer yield.

According to an embodiment of the present application, a backplane for bonding light-emitting elements is provided. A first bonding pad and a second bonding pad for bonding light-emitting elements are provided on the surface of the backplate. The second bonding pad is used for bonding light-emitting elements. The pad is used as a repair pad, wherein the first pad includes a first adhesive layer and a first bonding layer, the second pad includes a second adhesive layer and a second bonding layer, and the Both the first bonding layer and the second bonding layer are multi-layer structures, the multi-layer structure includes multiple pure metal layers, and the bonding temperature of the first bonding layer is higher than that of the second bonding layer. The bonding temperature of the layer.

Optionally, the first bonding layer and the second bonding layer have the same number of pure metal layers, or the first bonding layer and the second bonding layer have different numbers of pure metal layers. metal layer.

Optionally, the first bonding layer includes at least two pure metal layers formed of different metals, and the second bonding layer includes at least two pure metal layers formed of different metals.

Optionally, both the first bonding layer and the second bonding layer include alternately stacked multiple pure metal layers formed of a first metal and a second metal, and the melting point of the first metal Higher than the melting point of the second metal.

Optionally, the thickness ratio of the pure metal layer formed by the first metal and the second metal is between 1:10 and 10:1.

Optionally, the pure metal layer formed by the first metal and the second metal has a first thickness ratio in the first bonding layer, and the pure metal layer formed by the first metal and the second metal A layer has a second thickness ratio in the second bonding layer, and the first thickness ratio is greater than the second thickness ratio.

Optionally, the stacking order of the multiple pure metal layers in the first bonding layer and the second bonding layer is different.

Optionally, at least one pure metal layer among the plurality of pure metal layers in the second bonding layer is formed from a material different from any one of the plurality of pure metal layers in the first bonding layer. of forming materials.

Optionally, the orthogonal projected area of the first bonding layer on the surface of the back plate is 1.15 to 2.5 times the orthogonal projected area of the first bonding layer on the surface of the back plate; and/or , the orthogonal projected area of the second bonding layer on the surface of the back plate is 1.15 to 2.5 times the orthogonal projected area of the second bonding layer on the surface of the back plate.

Optionally, the first bonding pad further includes a first connection electrode located on a side of the first adhesive layer facing away from the first bonding layer; the first adhesive layer is on a side of the backplane. The orthographic projection area of the surface is 1.15 to 2.5 times the orthographic projection area of the first connection electrode on the surface of the backplane; and/or, the second pad layer further includes a surface located on the second adhesive layer The second connection electrode on the side facing away from the second bonding layer; the orthogonal projected area of the second adhesive layer on the surface of the back plate is the area of the second connection electrode on the surface of the back plate. 1.15~2.5 times the orthographic projection area.

According to another embodiment of the present application, a display panel is provided, which includes:
A backplane having a first bonding pad and a second bonding pad formed on the backboard, wherein the first bonding pad includes a first adhesive layer and a first alloy, and the second bonding pad includes a second adhesive layer and a second bonding layer, the second bonding layer is a multi-layer structure, the multi-layer structure includes multiple pure metal layers; and a light-emitting element fixed on the backplane, the light-emitting element includes a first A light-emitting element, the first light-emitting element is welded to the first bonding pad through the first alloy, and the temperature at which the first alloy starts to melt is higher than the bonding temperature of the second bonding layer.

Optionally, the light-emitting element further includes a repaired light-emitting element, and the repaired light-emitting element is welded to at least one of the second bonding pads through a second alloy.

Optionally, the light-emitting element includes:
A semiconductor structure, the semiconductor structure including a first semiconductor layer with opposite conductivity types, a second semiconductor layer, and a light-emitting layer located between the first semiconductor layer and the second semiconductor layer;
An electrode structure includes a first electrode and a second electrode, the first electrode is conductively connected to the first semiconductor layer, the second electrode is conductively connected to the second semiconductor layer, and the light-emitting element is connected through the electrode The structure is welded to the backing plate.

Optionally, the orthogonal projected area of the second bonding layer on the surface of the back plate is 1.15 to 2.5 times the orthogonal projected area of the second bonding layer on the surface of the back plate.

According to yet another embodiment of the present application, a light-emitting element for a display panel is provided. The light-emitting element is divided into a first light-emitting element and a first light-emitting element used to replace the first light-emitting element that cannot light up normally in the display panel. Repair a light-emitting element, the light-emitting element includes a semiconductor structure and an electrode structure formed on the surface of the semiconductor structure, the electrode structure of the first light-emitting element includes a first welding layer, the electrode structure of the repair light-emitting element includes a second Welding layer, the first welding layer and the second welding layer are both multi-layer structures, the multi-layer structure includes multiple pure metal layers, and the bonding temperature of the first welding layer is higher than that of the third welding layer. The bonding temperature of the two welding layers.

beneficial effects

As mentioned above, the display panel of the present application, the light-emitting element and the backplane used for the display panel have the following beneficial effects:
A first bonding pad and a second bonding pad used as a repair pad are formed on the backplane of the present application. The first bonding pad includes a first adhesive layer and a first bonding layer, and the second bonding pad includes a second bonding layer. layer and the second bonding layer, the first bonding layer and the second bonding layer are all multi-layer structures. The multi-layer structure includes multiple pure metal layers. By controlling the high melting point metal layer and the low melting point metal layer in the multi-layer pure metal layer The content of the metal layer (for example, the thickness ratio) controls the bonding temperature of the first bonding layer and the second bonding layer, so that the bonding temperature of the first bonding layer is higher than the bonding temperature of the second bonding layer. The above-mentioned multiple pure metal layers are formed on the first and second bonding pads by evaporation, thereby ensuring the purity of each pure metal layer and facilitating the subsequent formation of alloys with different melting points. At the first bonding temperature, the first bonding layer melts to form a first alloy to fix the LED chip to the first pad of the backplane; at the same time, the second bonding layer on the second pad melts to form a second An alloy whose melting temperature of the second alloy is lower than the melting temperature of the first alloy. Therefore, when the second pad is heated to weld the repair LED chip, the first alloy on the first pad will not melt, ensuring the stability of the LED chip on the first pad and preventing batch deviation. This ensures the yield of LED chip batch transfer.

The pure metal layers forming the first bonding layer and the second bonding layer may be alternately stacked pure metal layers formed of the same metals, and the stacking order of pure metals formed of the same metal may be the same or different. ; Or at least one layer of pure metal in the second bonding layer is made of a material different from the material of any pure metal layer in the first bonding layer. This increases the selection range of pure metals for forming the first bonding layer and the second bonding layer, and increases the design flexibility and adaptability of the pads.

The light-emitting element in this application is divided into a first light-emitting element and a second light-emitting element for repair. The electrode structure of the first light-emitting element includes a first welding layer. The electrode structure of the repair light-emitting element includes a second welding layer. The first welding layer and the second soldering layer are all multi-layer structures, and the multi-layer structure has the same structural characteristics as the multi-layer structure of the first pad and the second pad on the backplane. Therefore, when using the light-emitting element of the present application, the same It can ensure that the first light-emitting element does not shift when welding and repairing the light-emitting element, thereby ensuring the transfer yield of the light-emitting element.

The display panel of the present application uses the backplane of the present application, and the light-emitting elements have a good transfer yield. Therefore, the display panel has a high mass production yield.

Description of the drawings

FIG. 1 shows a schematic structural diagram of a backplane for bonding light-emitting elements provided in Embodiment 1 of the present application.

Figure 2 shows a schematic diagram of soldering LED chips on the backplane shown in Figure 1.

Figure 3a shows a schematic structural diagram of a backplane used for bonding light-emitting elements in an optional embodiment of Embodiment 1 of the present application.

Figure 3b shows a schematic structural diagram of a backplane used for bonding light-emitting elements in another optional embodiment of Embodiment 1 of the present application.

Figure 3c shows a schematic structural diagram of a backplane used for bonding light-emitting elements in another optional embodiment of Embodiment 1 of the present application.

Figure 3d shows a schematic structural diagram of a backplane used for bonding light-emitting elements in another optional embodiment of Embodiment 1 of the present application.

Figure 3e shows a schematic structural diagram of a backplane used for bonding light-emitting elements in another optional embodiment of Embodiment 1 of the present application.

Figure 4a shows a schematic structural diagram of a display panel provided for Embodiment 2 of the present application.

Figure 4b shows a schematic structural diagram of a display panel in another optional embodiment of Embodiment 2 of the present application.

FIG. 5 is a schematic structural diagram of the light-emitting element in the display panel shown in FIG. 4a.

FIG. 6a shows a schematic structural diagram of the first light-emitting element of the light-emitting element provided in Embodiment 3 of the present application.

Figure 6b shows a schematic structural diagram of the repaired light-emitting element of the light-emitting element provided in Embodiment 3 of the present application.

FIG. 7 shows a schematic diagram of soldering the light-emitting element provided in Embodiment 3 on a backplane.

FIG. 8 shows a schematic structural diagram of a light-emitting element repaired as an optional embodiment of Embodiment 3 of the present application.

FIG. 9 shows a schematic structural diagram of a light-emitting element repaired as an optional embodiment of Embodiment 3 of the present application.

FIG. 10 shows a schematic structural diagram of a display panel provided in Embodiment 4 of the present application.

Component label description

100	backplane	3011	first light emitting element
101	first pad	3012	Repair light-emitting components
1011	first bonding layer	301-1	substrate
1012	first bonding layer	301-2	first semiconductor layer
1012-1	first pure metal layer	301-3	active layer
1012-2	Second pure metal layer	301-4	second semiconductor layer
102	Second pad	301-5	Insulating protective layer
1021	Second adhesive layer	301-6	Electrode structure
1022	Second bonding layer	301-61	Ohmic contact layer
1022-1	The third pure metal layer	301-62	first welding layer
1022-2	The fourth pure metal layer	301-621	The sixth pure metal layer
1022-3	The fifth pure metal layer	301-622	The seventh pure metal layer
1013	first alloy	3012-62	Second welding layer
1023	Second alloy	3012-621	The eighth pure metal layer
1014	first connection electrode	3012-622	Ninth pure metal layer
1024	second connecting electrode	3012-623	The tenth pure metal layer
200	display panel	301-63	Third alloy
201	backplane	301-64	Fourth alloy
202	Light emitting element	302	backplane
2021	first light emitting element	3021	first pad
2022	Repair light-emitting components	3022	Second pad
202-1	substrate	400	display panel
202-2	first semiconductor layer	401	backplane
202-3	active layer	4011	first pad
202-4	second semiconductor layer	4012	Second pad
202-5	Insulating protective layer	402	Light emitting element
202-6	Electrode structure
202-61	first electrode
202-62	second electrode

Best Mode of Carrying Out the Invention

Type here the paragraph describing the best mode for carrying out the invention.

Embodiments of the invention

The following describes the implementation of the present application through specific examples. Those skilled in the art can easily understand other advantages and effects of the present application from the content disclosed in this specification. This application can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of this application.

Embodiment 1

This embodiment provides a backplane for bonding light-emitting elements. As shown in Figure 1, the surface of the backplane 100 is provided with a first bonding pad 101 and a second bonding pad 102 for bonding light-emitting elements, wherein the first bonding pad 101 is used for welding the first transfer to the backplane. The first light-emitting element 2021 (see Figure 2) on 100 is the main light-emitting element; the second pad 102 is used as a repair pad for welding the repair light-emitting element 2022 (see Figure 2) that replaces the main light-emitting element that cannot work properly. ). Referring also to FIG. 1 , the first bonding pad 101 includes a first adhesive layer 1011 and a first bonding layer 1012 , wherein the first bonding layer 1012 is a multi-layer structure. The second bonding pad 102 includes a second adhesive layer 1021 and a second bonding layer 1022, wherein the second bonding layer 1022 is also a multi-layer structure. In an optional embodiment, the multi-layer structures of the first bonding layer 1012 and the second bonding layer 1022 are both multi-layer pure metal layers. For example, it can be two, three, four or even more pure metal layers. The number of pure metal layers can be flexibly set according to the design requirements of the first bonding pad 101 and the second bonding pad 102, and the first bonding The number of pure metal layers in layer 1012 and second bonding layer 1022 may be the same or different.

Referring to Figure 1, in an optional embodiment, the first bonding layer 1012 includes a first pure metal layer 1012-1 and a second pure metal layer 1012-2, the first pure metal layer 1012-1 and the second pure metal layer 1012-2 is a pure metal layer formed of different pure metals, and the melting point of the pure metal forming the first pure metal layer 1012-1 is higher than the melting point of the pure metal forming the second pure metal layer 1012-2. For example, the first pure metal layer 1012-1 may be a Sn metal layer, and the second pure metal layer 1012-2 may be an In metal layer. The second bonding layer 1022 and the first bonding layer 1012 include the same number of pure metal layers, that is, they include a third pure metal layer 1022-1 and a fourth pure metal layer 1022-2. In this embodiment, the third pure metal 1022-1 and the first pure metal layer 1012-1, the fourth pure metal layer 1022-2 and the second pure metal layer 1012-2 are respectively formed of the same pure metal. The metal layer, for example, the above-mentioned third pure metal layer 1022-1 is also a Sn metal layer, and the fourth pure metal layer 1022-2 is also an In metal layer. And the stacking sequence of pure metal layers formed of the same pure metal in the first bonding layer 1012 and the second bonding layer 1022 is the same, that is, the second pure metal layer 1012-2 shown in Figure 1 is located in the first pure metal layer 1012 Above -1, the fourth pure metal layer 1022-2 is located above the third pure metal layer 1022-1.

Optionally, the thickness ratio of the high melting point pure metal layer to the low melting point pure metal layer is between 1:10~10:1. In order to obtain different welding temperatures, the high melting point pure metal layer and the low melting point pure metal layer are There are first thickness ratios and second thickness ratios in the first bonding layer 1012 and the second bonding layer 1022 respectively, and the first thickness ratio is greater than the second thickness ratio, that is, the first thickness ratio in the first bonding layer 1012 is The first thickness ratio of a pure metal layer 1012-1 and the second pure metal layer 1012-2 is compared with the second thickness ratio of the third pure metal layer 1022-1 and the fourth pure metal layer 1022-2 in the second bonding layer 1022. The thickness ratios are not the same, and the first thickness ratio of the first pure metal layer 1012-1 and the second pure metal layer 1012-2 is greater than the second thickness ratio of the third pure metal layer 1022-1 and the fourth pure metal layer 1022-2. thickness ratio. For example, optionally, the first thickness ratio is 10:1 and the second thickness ratio is 4:6; or the first thickness ratio is 4:6 and the second thickness ratio is 1:10; or the first thickness ratio is 8:1, and the second thickness ratio is 2:1; or, the first thickness ratio is 5:7, and the second thickness ratio is 3:8. The above-mentioned different thickness ratios also indicate that the contents of different pure metal layers in the first bonding layer 1012 and the second bonding layer 1022 are different. Since different metals have different melting points, by controlling the difference in the thickness ratio and controlling the content of the pure metal layer with a higher melting point in the first bonding layer 1012 to be greater than the content in the second bonding layer 1022, it is possible to The first bonding layer 1012 and the second bonding layer 1022 are controlled to have different bonding temperatures, and the bonding temperature of the second bonding layer 1022 is lower than the bonding temperature of the first bonding layer 1012 .

As mentioned above, the first bonding layer 1012 and the second bonding layer 1022 have the above structural features, which cause the first bonding layer 1012 and the second bonding layer 1022 to have different bonding temperatures, and the second bonding layer 1012 has the above structural features. The bonding temperature of the bonding layer 1022 is lower than the bonding temperature of the first bonding layer 1012 . As shown in FIG. 2 , in the first bonding layer 1012 , the first thickness ratio of the first pure metal layer 1012 - 1 and the second pure metal layer 1012 - 2 is 10:1. In the second bonding layer 1022 , the second thickness ratio of the third pure metal layer 1022-1 and the fourth pure metal layer 1022-2 is 4:6. For example, when welding the light-emitting element on the backplane 100 shown in Figure 1, the first light-emitting element is welded first. Component 2021. At this time, the first bonding layer 1012 on the first pad 101 has a higher melting start temperature - 200°C. In view of this, the first light-emitting component 2021 is transferred to the backplane 100 once and then hot-keyed. Combine and heat to about 260°C to ensure that the first bonding layer 1012 of the first bonding pad 101 is completely melted to form the first alloy 1013, thereby achieving sufficient thermal bonding of the first light-emitting element 2021. The melting temperature of the first alloy 1013 formed by heating the first bonding layer 1012 is approximately 200°C. Since the second bonding layer 1022 of the second bonding pad 102 has a lower starting melting temperature, during this heating process, the second bonding layer 1022 is also completely melted and the second alloy 1023 is formed. In view of the second bonding With the above structural design of the layer 1022 and the first bonding layer 1021, the second alloy 1023 formed by the second bonding layer 1022 has a lower melting temperature than the first alloy 1013. In this embodiment, the second alloy The melting temperature of 1023 is approximately 125°C. Therefore, after the repaired light-emitting element 2022 is transferred to the back plate 100, thermal bonding is performed again. At this time, the back plate 100 is heated to about 150°C and lower than 200°C. At this time, the second alloy 1023 can be guaranteed to be completely melted, and The first alloy 1013 of the first bonding pad 101 will not melt, thereby ensuring that the first light-emitting element 2021 will not be displaced or detached, and at the same time, it can also ensure that the repaired light-emitting element 2022 is fully bonded to the backplane 100 .

In an optional embodiment, after the first light-emitting element 2021 is once transferred to the back plate 100, thermal bonding is performed, and the back plate 100 is heated by local heating, that is, only the first light-emitting element 2021 transferred with the first light-emitting element 2021 is heated. For the bonding pad 101, heat the first bonding pad 101 to about 260°C to ensure that the first bonding layer 1012 of the first bonding pad 101 is completely melted to form the first alloy 1013, thereby achieving sufficient thermal bonding of the first light-emitting element 2021. The melting temperature of the first alloy 1013 formed by heating the first bonding layer 1012 is approximately 200°C. During the process of bonding the first light-emitting element 2021, the second bonding pad 102 is not heated or is heated to a relatively small extent, and the second bonding layer 1022 of the second bonding pad 102 will not melt or soften or will not melt completely. Maintain the multi-layer pure metal layer structure or part of the multi-layer pure metal layer structure. When it is necessary to bond and repair the light-emitting element 2022, after the repaired light-emitting element 2022 is transferred to the backplane 100, thermal bonding is performed again, and local heating is also performed. The second pad 102 with the repaired light-emitting element 2022 is heated and transferred, and the backplane 100 is heated. to about 150°C and lower than 200°C. At this time, the second bonding layer 1022 can be guaranteed to be completely melted, but the first alloy 1013 of the first bonding pad 101 will not melt, thereby ensuring that the first light-emitting element 2021 will not appear. Risks such as displacement or falling off can be avoided, while ensuring that the repaired light-emitting element 2022 is fully bonded to the backplane 100 .

In addition, in this embodiment, a multi-layer pure metal layer of the first bonding layer 1012 and the second bonding layer 1022 is formed using an evaporation method. In this method, pure metal is used as the evaporation metal source. A pure metal layer is obtained above the junction layer 1011 or the second bonding layer 1021). Different pure metal layers can be obtained by selecting different evaporation metal sources and the thickness of each pure metal layer can be precisely controlled, thereby achieving the above structural requirements. of multiple layers of pure metal.

In an optional embodiment of this embodiment, the first bonding layer 1012 and the second bonding layer 1022 include the same number of pure metal layers formed of the same pure metal, and the pure metal layers formed of the same pure metal are The stacking order in the first bonding layer 1012 and the second bonding layer 1022 is different. As shown in Figure 3a, the third pure metal layer 1022-1 in the second bonding layer 1022 and the first pure metal layer 1012-1 in the first bonding layer 1012, the fourth pure metal layer 1022-1 in the second bonding layer 1022 The pure metal layer 1022-2 and the second pure metal layer 1012-2 in the first bonding layer 1012 are respectively pure metal layers formed of the same pure metal. For example, as mentioned above, the first pure metal layer 1012-1 and The third pure metal layer 1022-1 may be a Sn metal layer, and the second pure metal layer 1012-2 and the fourth pure metal layer 1022-2 may be an In metal layer. However, in this optional embodiment, as shown in FIG. 3a, the third pure metal layer 1022-1 and the fourth pure metal layer 1022-2 in the second bonding layer 1022 are different from the first pure metal layer 1022-2 in the first bonding layer 1012. The stacking order of the metal layer 1012-1 and the second pure metal layer 1012-2 is different, that is, the second pure metal layer 1012-2 shown in Figure 3a is located above the first pure metal layer 1012-1, and the fourth pure metal layer 1022-2 is located below the third pure metal layer 1022-1. The stacking sequence of multiple pure metal layers can also meet the requirements of different bonding temperatures, while increasing the design flexibility of the pad.

As mentioned above, the multi-layer metal layers in the first bonding layer 1012 and the second bonding layer 1022 are respectively pure metal layers formed of the same metal. It can be understood that according to the eutectic theory of metals, the first bonding layer 1012 and the second bonding layer 1022 may include pure metal layers formed of different metals. For example, at least one pure metal layer in the second bonding layer 1022 is formed of a material and any layer of pure metal in the first bonding layer 1012 The layers are all made of different materials. Alternatively, the first bonding layer 1012 includes a Sn layer and a Zn layer, and the second bonding layer 1022 includes a Sn layer and an In layer, or the first bonding layer 1012 includes an Ag layer and a Zn layer, and the second bonding layer 1022 includes an Ag layer and a Zn layer. Layer 1022 includes a Bi layer and a Sn layer. It is only necessary that the bonding temperature of the first bonding layer 1012 is higher than the bonding temperature of the second bonding layer 1022 .

In another optional embodiment of this embodiment, the first bonding layer 1012 and the second bonding layer 1022 have different numbers of pure metal layers, and the first bonding layer 1012 and the second bonding layer 1022 have different numbers of pure metal layers. The pure metal layer may be multiple pure metal layers formed of the same pure metal, or may include multiple pure metal layers formed of different pure metals. As shown in Figure 3b, the first bonding layer 1012 includes a first pure metal layer 1012-1 and a second pure metal layer 1012-2, and the second bonding layer 1022 includes a third pure metal layer 1022-1, a fourth pure metal layer 1022-1, and a fourth pure metal layer 1022-1. Metal layer 1022-2 and fifth pure metal layer 1022-3. In an optional embodiment, the first pure metal layer 1012-1 and the second pure metal layer 1012-2 may be Sn layers and Ag layers respectively, while the third pure metal layer 1022-1 and the fourth pure metal layer 1022- 2 and the fifth pure metal layer 1022-3 are Sn layer, In layer and Bi layer respectively.

In this embodiment, the pure metal layers in the first bonding layer 1012 and the second bonding layer 1022 can be selected from the combinations shown in Table 1 below, and the stacking sequence can be changed according to actual needs.

Table 1 Pure metal layer combinations of the first bonding layer and the second bonding layer

serial number	first bonding layer	Second bonding layer
1	Sn+In	Sn+In
2	Sn+B	Sn+In
3	Sn+B	Sn+Bi+In
4	Sn+Ag	Sn+B
5	Sn+Zn	Sn+Zn+Bi

As shown in Table 1 above, optional pure metal layer combinations of the first bonding layer 1012 and the second bonding layer 1022 are only exemplary. The above combinations are only exemplary, although the first bonding layer 1012 is only In addition to the combination of two pure metal layers, it can be understood that the first bonding layer 1012 can also include three or more pure metal layers. Similarly, the second bonding layer 1022 can also include three or more layers. A pure metal layer, and the multiple pure metal layers of the first bonding layer 1012 and the second bonding layer 1022 can be arbitrarily combined under the condition that the bonding temperature is satisfied.

In an optional embodiment of this embodiment, the orthogonal projected areas of the first adhesive layer 1011 and the first bonding layer 1012 in the first bonding pad 101 on the surface of the backplane 100 are different, and the first adhesive layer 1011 is The orthogonal projected area of the surface of the back plate 100 is denoted as S1, and the orthogonal projected area of the first bonding layer 1012 on the surface of the back plate 100 is denoted as S2. Specifically, S1>S2, more specifically, S1 is 1.15~2.5 times of S2. It is shown in FIG. 3 c that the width of the first adhesive layer 1011 is greater than the width of the first bonding layer 1012 . It can be understood that the orthographic projection of the first bonding layer 1012 on the surface of the back plate 100 falls within the orthographic projection of the first adhesive layer 1011 on the surface of the back plate 100 . In an optional embodiment, the orthogonal projected areas of the second adhesive layer 1021 and the second bonding layer 1022 in the second bonding pad 102 on the surface of the back plate 100 are different, and the second adhesive layer 1021 is on the surface of the back plate 100 The orthographic projection area of the second bonding layer 1022 on the surface of the back plate 100 is designated as S3 . Specifically, S3>S4. More specifically, S3 is 1.15~2.5 times that of S4. It is shown in FIG. 3 c that the width of the second adhesive layer 1021 is greater than the width of the second bonding layer 1022 . It can be understood that the orthographic projection of the second bonding layer 1022 on the surface of the back plate 100 falls within the orthographic projection of the second adhesive layer 1021 on the surface of the back plate 100 . The ratio of S1 to S2 and the ratio of S3 to S4 may be the same or different. For example, S1 is 1.2 times that of S2, and S3 is 2.0 times that of S4, or S1 is 2.2 times that of S2, and S3 is 1.5 times that of S4. The above are only examples and cannot be used as conditions to limit this embodiment. The materials of the first bonding layer 1011 and the second bonding layer 1012 can be Cr, Ni, etc., and the first bonding layer 1011 is set to be larger than the first bonding layer 1012 (the second bonding layer 1021 is set to be larger than The second bonding layer 1022 is larger), which can provide a better welding effect and can reduce the problem of the first bonding layer 1012 (or the second bonding layer 1022) melting and overflowing to the surroundings during the welding process.

In an optional embodiment of this embodiment, referring to Figure 3d, the difference from Figure 3c is that the first adhesive layer 1011 also extends to the first bonding layer 1012 toward the side close to the first bonding layer 1012 side. It can also be understood that a groove structure is formed on the first bonding layer 1011, and the first bonding layer 1012 is disposed in the groove structure. The second adhesive layer 1021 also extends toward the side close to the second bonding layer 1022 to the side surface of the second bonding layer 1022 . It can also be understood that a groove structure is formed on the second adhesive layer 1021, and the second bonding layer 1022 is disposed in the groove structure. The depth of the groove formed by the first bonding layer 1011 may be less than or equal to the thickness of the nearest metal layer in contact with the multi-layer metal of the first bonding layer 1012 . The depth of the groove formed by the second bonding layer 1021 may be less than or equal to the thickness of the nearest metal layer in contact with the multi-layer metal of the second bonding layer 1022 . The depths of the grooves formed by the first adhesive layer 1011 and the second adhesive layer 1021 may be the same or different. Compared with the embodiment shown in FIG. 3c, the embodiment shown in FIG. 3d can further reduce the problem of the first bonding layer 1012 (or the second bonding layer 1022) melting and spilling to the surroundings during the bonding process.

In an optional embodiment of this embodiment, the first bonding pad 101 further includes a first connection electrode 1014 disposed on the side of the first adhesive layer 1011 facing away from the first bonding layer 1012, and the second bonding pad 102 further includes The second connection electrode 1024 is provided on the side of the second adhesive layer 1021 facing away from the second bonding layer 1022. The first connection electrode 1014 and the second connection electrode 1024 are respectively connected to the circuit inside the backplane 100 . The first adhesive layer 1011 can be used to block the first connection electrode 1014 and the first bonding layer 1012, and the second adhesive layer 1021 can be used to block the second connection electrode 1024 and the second bonding layer 1022 to act as a solder resist. Referring to FIG. 3e , the orthogonal projected area of the first adhesive layer 1011 on the surface of the back plate 100 is denoted as S1 , the orthogonal projected area of the first bonding layer 1012 on the surface of the back plate 100 is denoted as S2 , and the second adhesive layer 1021 The orthogonal projected area of the second bonding layer 1022 on the surface of the back plate 100 is denoted as S3 , and the orthogonal projected area of the second bonding layer 1022 on the surface of the back plate 100 is denoted as S4 . The orthographic projection area of the first connection electrode 1014 on the surface of the back plate 100 is denoted as S5, and the orthogonal projection area of the second connection electrode 1024 on the surface of the back plate 100 is denoted as S6. In an optional embodiment, S1>S5, more specifically, S1 is 1.15~2.5 times of S5. In an optional embodiment, S3>S6, more specifically, S3 is 1.15~2.5 times of S6. The ratio of S1 to S5 and the ratio of S3 to S6 may be the same or different. For example, S1 is 1.8 times that of S5, S3 is 2.4 times that of S6, or S1 is 2.2 times that of S5, and S3 is 1.2 times that of S6. The above are only examples and cannot be used as conditions to limit this embodiment. S2 and S5 may be equal or unequal, S2 may be greater than S5, or S2 may be less than S5, which is not limited in this embodiment. S4 and S6 may be equal or unequal, S4 may be greater than S6, or S4 may be less than S6, which is not limited in this embodiment.

Continuing to refer to FIG. 3e , the first adhesive layer 1011 can extend toward the side near the first connection electrode 1014 to the side of the first connection electrode 1014 , and the second adhesive layer 1021 can extend toward the side near the first connection electrode 1024 Extending to the side of the second connection electrode 1024. The first connection electrode 1014 and the second connection electrode 1024 can be better isolated, thereby achieving a better solder resist effect. The height of the first adhesive layer 1011 extending toward the first connection electrode 1014 may be less than the thickness of the first connection electrode 1014 , or may be equal to the thickness of the first connection electrode 1014 . The height of the second adhesive layer 1021 extending toward the second connection electrode 1024 may be less than the thickness of the second connection electrode 1014 or equal to the thickness of the second connection electrode 1024 . This embodiment is not limiting.

Embodiment 2

This embodiment provides a display panel. As shown in FIG. 4a , the display panel 200 of this embodiment includes a backplane 201 and a light-emitting element 202 located above the backplane 201 . As shown in FIG. 4a , the backplane 201 includes a first bonding pad 101 and a second bonding pad 102 . The first bonding pad 101 includes a first adhesive layer 1011 (see FIG. 1 ) and a first alloy 1013 . The light-emitting element 202 includes a first light-emitting element 2021 fixed on the first bonding pad 101, and the first light-emitting element 2021 is welded to the first bonding pad 101 through the first alloy 1013. As described in the first embodiment above, the first alloy 1013 formed by heating the first bonding layer 1012 of the first light-emitting element 2021 at the first bonding temperature is fixed to the first bonding pad 101 . In an optional embodiment, the first bonding layer 1012 includes multiple layers of pure metal layers formed of metals with different melting points. For example, the first bonding layer 1012 has the structure described in Embodiment 1. Structural characteristics of the first bonding layer 1012. When the back plate 201 is heated and the first light-emitting element 2021 is welded, the multiple pure metal layers of the first bonding layer 1012 are melted to form the first alloy 1013, and the first light-emitting element 2021 is fixed to the first pad 101 of the back plate 201. at. In another optional embodiment, a uniform alloy solder is formed above the first adhesive layer 1011. When the back plate 201 is heated to weld the first light-emitting element 2021, the alloy solder melts to form the above-mentioned first alloy 1013, and the first light-emitting element 2021 is heated. The component 2021 is fixed to the first pad 101 of the backplane 201 .

In this embodiment, the second bonding pad 102 includes a second adhesive layer 1021 (see FIG. 1 ) and a second bonding layer 1022 , where the second bonding layer 1022 is a multi-layer structure, and the multi-layer structure is a multi-layer structure. Pure metal layer, for example, 2 layers, 3 layers or even more layers of pure metal. The metal forming the above pure metal layer can be selected from the metals shown in Table 1 in Implementation 1. Moreover, the second bonding layer 1022 formed of multiple pure metal layers has a lower melting temperature than the first alloy 1013.

As shown in FIG. 3 c and FIG. 3 d in the first embodiment above, the orthogonal projected area S3 of the second adhesive layer 1021 on the surface of the back plate 100 and the orthogonal projected area of the second bonding layer 1022 on the surface of the back plate 100 are denoted S4 The relationship can be S3>S4, more specifically, S3 is 1.15~2.5 times of S4. It can provide better welding effect, and can reduce the problem of the second bonding layer 1022 melting and overflowing to the periphery during the process of welding the repaired light-emitting element 2022 to the backplane 100 .

Referring also to FIG. 4a, the light-emitting element 202 of the display panel 200 may also include at least one repair light-emitting element 2022, which is used to replace the first light-emitting element 2021 on the back panel 201 that is damaged or cannot light normally. At least one repaired light emitting element 2022 is soldered to at least one second pad 102 via the second alloy 1023 . As mentioned above, since the second bonding layer 1022 has a lower melting temperature than the first alloy 1013, that is, the second welding temperature of the second bonding layer 1022 is lower than the temperature at which the first alloy 1013 starts to melt, therefore, at least After a repair light-emitting element 2022 is transferred to at least one second bonding pad 102, the at least one second bonding pad 102 is heated at a second bonding temperature until the multi-layer pure metal layer of the second bonding layer 1022 is completely melted. The second bonding layer 1022 forms a second alloy 1023. After stopping heating, the second alloy 1023 fixes the repaired light-emitting element 2022 to the second bonding pad 102. During this process, the second bonding pad 102 where the light-emitting element 2022 has not been transferred still retains the second bonding layer 1022 having a multi-layer structure. Therefore, the second bonding pad 102 on the backplane 201 of the display panel 200 has two forms: in one form, the second bonding pad 102 includes a second adhesive layer 1021 and a second bonding layer 1022 with a multi-layer structure. ; In another form, the second bonding pad 102 includes a second adhesive layer 1021 and a second alloy 1023. During the process of welding and repairing the light-emitting element 2022, the first alloy 1013 will not soften or melt, so the first light-emitting element 2021 on the first pad 101 will not have the risk of shifting or falling off, and will not affect the first light-emitting element. 2021 stability, thereby ensuring the overall yield of the display panel 200.

In an optional embodiment, the second bonding pad 102 includes a second adhesive layer 1021 (see FIG. 1 ) and a second alloy 1023 . The second alloy 1023 is a uniform alloy formed above the second adhesive layer 1021 solder. The uniform alloy solder also has a lower melting temperature than the first alloy 1013. Therefore, when bonding to repair the light-emitting element 2022, the first alloy 1013 will not soften or melt, ensuring that the first alloy solder on the first pad 101 is bonded. The light-emitting element 2021 will not have the risk of shifting or falling off, and will not affect the stability of the first light-emitting element 2021, thereby ensuring the overall yield of the display panel 200.

The second bonding layer 1022 of the above-mentioned multi-layer structure has a higher melting start temperature than the second alloy 1023 formed of a uniform alloy solder. Therefore, during the soldering process of the first light-emitting element 2021, it has better Thermal stability of the first light-emitting element 2021 will not be softened or melted due to thermal bonding, ensuring the integrity and stability of the second bonding pad 102.

In conjunction with the above embodiment 1, Figure 4b shows that the first bonding pad 101 also includes a first connection electrode 1014 disposed on the side of the first adhesive layer 1011 facing away from the first bonding layer 1012, and the second bonding pad 102 also It includes a second connection electrode 1024 disposed on the side of the second adhesive layer 1021 facing away from the second bonding layer 1022 . The orthographic projection area S1 of the first adhesive layer 1011 on the surface of the back plate 100 is greater than the orthographic projection area S5 of the first connection electrode 1014 on the surface of the back plate 100 , and the orthographic projection area S1 of the second adhesive layer 1021 on the surface of the back plate 100 In an embodiment in which the area S3 is larger than the orthogonal projection area S6 of the second connection electrode 1024 on the surface of the back plate 100, please refer to the description of FIG. 3e in the first embodiment for details.

As shown in Figure 5, in this embodiment, the light-emitting element 202 is an LED chip. The LED chip includes a substrate 202-1, a first semiconductor layer 202-2 formed on the substrate 202-1, and a first semiconductor layer 202-2. The second semiconductor layer 202-4 of the opposite conductivity type of 202-2 and the active layer 202-3 located between the first semiconductor layer 202-2 and the second semiconductor layer 202-4, the active layer 202-3 is The light-emitting layer of the light-emitting element 202 also includes an insulating protective layer 202-5 formed on the surface of the light-emitting element 202. The first semiconductor layer 202-2 may be an N-type semiconductor layer, and the second semiconductor layer 202-4 may be a P-type semiconductor layer. Of course, it is also possible that the first semiconductor layer 202-2 is a P-type semiconductor layer and the second semiconductor layer 202-4 is an N-type semiconductor layer. In an optional embodiment, the first semiconductor layer 202-2 may be an N-type GaN layer, the active layer 202-3 may be a quantum well layer, and the second semiconductor layer 202-4 may be a P-type GaN layer. Alternatively, the first semiconductor layer 202-2 may be an N-type GaN layer, such as a Si-doped GaN layer; the active layer 202-3 may be an InGaN/GaN multiple quantum well, and the second semiconductor layer 202-4 may be a p-type GaN layer. layer, such as a Mg-doped GaN layer.

Referring also to FIG. 5 , the LED chip of this embodiment further includes an electrode structure 202 - 6 , through which the light-emitting element 202 is fixed to the first pad 101 or the second pad 102 of the backplane 201 . The electrode structure 202-6 includes a first electrode 202-61 and a second electrode 202-62. The first electrode 202-61 is connected to the first semiconductor layer 202-2, and the second electrode 202-62 is connected to the second semiconductor layer 202-62. 4 connections. Referring also to FIG. 5 , the first semiconductor layer 202-2 may be formed with a mesa, and metal materials, such as Au, Ag, Al, Cu, Zn, etc., are deposited on the mesa to form the above-mentioned first electrode 202-61. Similarly, Au, Ag, Al, Cu, etc. are deposited on the second semiconductor layer 202-4 to form the second electrode 202-62. It can be understood that structures such as a transparent conductive layer and a current blocking layer may also be formed above the second semiconductor layer 202-4.

Embodiment 3

This embodiment provides a light-emitting element for a display panel. Referring to Figures 6a and 6b, the light-emitting element includes a first light-emitting element 3011 used as a main light-emitting element of the display panel, and is used in repairing replacement display panels. Repair the light-emitting element 3012 of the first light-emitting element 3011 that cannot light up normally.

In this embodiment, the first light-emitting element 3011 and the repair light-emitting element 3012 are both LED chips. 6a and 6b, the LED chip includes a substrate 301-1, a first semiconductor layer 301-2 formed on the substrate 301-1, and a second semiconductor layer 301-2 having an opposite conductivity type. The semiconductor layer 301-4 and the active layer 301-3 located between the first semiconductor layer 301-2 and the second semiconductor layer 301-4. The active layer 301-3 is the light-emitting layer of the LED chip, and also includes forming Insulating protective layer 301-5 on the surface of the LED chip. The first semiconductor layer 301-2 may be an N-type semiconductor layer, and the second semiconductor layer 301-4 may be a P-type semiconductor layer. Of course, it is also possible that the first semiconductor layer 301-2 is a P-type semiconductor layer and the second semiconductor layer 301-4 is an N-type semiconductor layer. In an optional embodiment, the first semiconductor layer 301-2 may be an N-type GaN layer, the active layer 301-3 may be a quantum well layer, and the second semiconductor layer 301-4 may be a P-type GaN layer. Alternatively, the first semiconductor layer 301-2 may be an N-type GaN layer, such as a Si-doped GaN layer; the active layer 301-3 may be an InGaN/GaN multiple quantum well, and the second semiconductor layer 301-4 may be a p-type GaN layer. layer, such as a Mg-doped GaN layer. Referring also to Figures 6a and 6b, the first light-emitting element 3011 and the repaired light-emitting element 3012 of this embodiment also include electrode structures 301-6. The first light-emitting element 3011 and the repaired light-emitting element 3012 are respectively fixed to the back through electrode junctions 301-6. Plate 302 (see Figure 7).

Referring to Figure 6a, the electrode structure 301-6 of the first light-emitting element 3011 includes an ohmic contact layer 301-61 and a first welding layer 301-62. The ohmic contact layer 301-61 is formed on the first semiconductor layer 301-2 and the second welding layer respectively. Above the semiconductor layer 301-4, an ohmic contact is formed. First soldering layers 301-62 are formed above the ohmic contact layers 301-61 on the first semiconductor layer 301-2 and the second semiconductor layer 301-4 respectively, for soldering the LED chip to the backplane 302 (see Figure 7) pads and achieve electrical connection. The first welding layer 301-62 is a multi-layer structure. Preferably, the multi-layer structure is a multi-layer pure metal layer. As illustrated in Figure 6a, the first welding layer 301-62 includes sixth pure metal layer 301-621 and seventh pure metal layer 301-622, sixth pure metal layer 301-621 and seventh pure metal layer 301-622 Pure metal layers formed of different pure metals, and the melting point of the sixth pure metal layer 301-621 is higher than the melting point of the seventh pure metal layer 301-622. For example, the sixth pure metal layer 301-621 may be a Sn metal layer, and the seventh pure metal layer 301-622 may be an In metal layer.

Referring to Figure 6b, the electrode structure 301-6 of the repaired light-emitting element 3012 includes an ohmic contact layer 301-61 and a second solder layer 3012-62. The ohmic contact layer 301-61 is formed on the first semiconductor layer 301-2 and the second semiconductor layer respectively. Above layer 301-4, an ohmic contact is formed. Second soldering layers 3012-62 are respectively formed above the ohmic contact layers 301-61 on the first semiconductor layer 301-2 and the second semiconductor layer 301-4 for soldering the repaired light-emitting element 3012 to the back plate 302 (see FIG. 7) on the repair pad and achieve electrical connection. In this embodiment, the second welding layer 3012-62 is also a multi-layer structure. Preferably, the multi-layer structure is a multi-layer pure metal layer. As shown in Figure 6b, the second welding layer 3012-62 and the first welding layer 301-62 have the same number of pure metal layers. As shown in Figure 6b, the second welding layer 3012-62 includes an eighth pure metal layer. 3012-621 and the ninth pure metal layer 3012-622. In this embodiment, the eighth pure metal 3012-621, the sixth pure metal layer 301-621, the ninth pure metal layer 3012-622, and the seventh pure metal layer 301-622 are respectively made of the same pure metal. For example, in the repaired light-emitting element 3012, the eighth pure metal layers 3012-621 are also Sn metal layers, and the ninth pure metal layers 3012-622 can also be In metal layers. And the stacking order of pure metal layers formed of the same metal in the second welding layer 3012-62 and the first welding layer 301-62 is the same. That is, as shown in Figures 6a and 7b, in the direction gradually away from the ohmic contact layer 301-61, the first soldering layer 301-62 is sequentially stacked with the sixth pure metal layer 301-621 and the seventh pure metal layer 301-622. , the second welding layer 3012-62 sequentially stacks the eighth pure metal layer 3012-621 and the ninth pure metal layer 3012-622.

Optionally, the thickness ratio of the high melting point pure metal layer to the low melting point pure metal layer is between 1:10~10:1. In order to obtain different welding temperatures, the high melting point pure metal layer and the low melting point pure metal layer are The first welding layer 301-62 and the second welding layer 3012-62 have a third thickness ratio and a fourth thickness ratio respectively, and the third thickness ratio is greater than the fourth thickness ratio, that is, the first welding layer 301-62 The third thickness ratio of the sixth pure metal layer 301-621 and the seventh pure metal layer 301-622 to the eighth pure metal layer 3012-621 and the ninth pure metal layer 3012-622 in the second welding layer 3012-62 The fourth thickness ratio is not the same, and the third thickness ratio of the sixth pure metal layer 301-621 and the seventh pure metal layer 301-622 is greater than that of the eighth pure metal layer 3012-621 and the ninth pure metal layer 3012-622. Fourth thickness ratio. For example, optionally, the third thickness ratio is 10:1, and the fourth thickness ratio is 4:6; or, the third thickness ratio is 4:6, and the fourth thickness ratio is 1:10; or, the third thickness ratio The thickness ratio is 8:1, and the fourth thickness ratio is 2:1; or the third thickness ratio is 5:7, and the fourth thickness ratio is 3:8. The above-mentioned different thickness ratios also represent different contents of different pure metal layers in the first welding layer 301-62 or the second welding layer 3012-62. Since different metals have different melting points, therefore, by controlling the above-mentioned thickness ratios, Differently, the first soldering layer 301-62 and the second soldering layer 3012-62 can be controlled to have different bonding temperatures, and the bonding temperature of the second soldering layer 301-62 is lower than that of the first soldering layer 301-62. combined temperature.

As mentioned above, the first soldering layer 301-62 of the first light-emitting element 3011 and the second soldering layer 3012-62 of the repaired light-emitting element 3012 have the above structural features, which make the first soldering layer 301-62 and the second soldering layer The layers 3012-62 have different bonding temperatures, and the second solder layer 3012-62 has a lower bonding temperature than the first solder layer 301-62. As shown in FIG. 7 , when welding the light-emitting element on the back plate 302 , the first light-emitting element 3011 is first transferred to the first pad 3021 of the back plate 302 . The first welding layer 301-62 of the first light-emitting element 3011 has a relatively high melting start temperature - 200°C. In view of this, the first light-emitting element 3011 is thermally bonded and heated to about 260°C to ensure that the first light-emitting element 3011 The first welding layer 301-62 of 3011 is completely melted to form the third alloy 301-63, thereby achieving full thermal bonding of the first light-emitting element 3011. The melting temperature of the third alloy 301-63 formed by heating the first welding layer 301-62 is approximately 200°C.

When welding the repaired light-emitting element 3012, the repaired light-emitting element 3012 is first heated. Since the second welding layer 3012-62 has a lower starting melting temperature, during the heating process, the second welding layer 3012-62 is also completely The fourth alloy 301-64 is melted and formed. In view of the above structural design of the second welding layer 3012-62 and the first welding layer 301-62, the fourth alloy 301-64 formed by the second welding layer 3012-62 is compared with The third alloy 301-63 formed in the first welding layer 301-62 has a lower melting temperature. In this embodiment, the melting temperature of the fourth alloy 301-64 is approximately 125°C. After the above-mentioned fourth alloy 301-64 is formed, the repaired light-emitting element 3012 is transferred to the second repair pad 3022 of the backplane 302, and thermal bonding is performed again. At this time, the fourth alloy 301-64 is heated to 150°C. Around 200℃, it can ensure that the fourth alloy 301-64 is completely melted, while the third alloy 301-63 formed by the first welding layer 301-62 will not melt, thereby ensuring that the first light-emitting element 3011 will not There is no risk of displacement or falling off, and at the same time, it can ensure that the repaired light-emitting element 3012 is fully bonded to the backplane 302 .

In addition, in this embodiment, an evaporation method is used to form multiple pure metal layers of the first welding layer 301-62 and the second welding layer 3012-62. This method uses pure metal as the evaporation metal source, and in the ohmic contact layer 301-62 A pure metal layer is obtained above 61. By selecting different evaporated metal sources, different pure metal layers can be obtained and the thickness of each pure metal layer can be precisely controlled, thereby obtaining multi-layer pure metal layers that meet the above structural requirements.

In an optional embodiment of this embodiment, the first welding layer 301-62 and the second welding layer 3012-62 include the same number of pure metal layers formed of the same pure metal, and the pure metal layers formed of the same pure metal The stacking order of the layers in the first solder layer 301-62 and the second solder layer 3012-62 is different. As shown in Figure 8, referring to Figure 6a at the same time, the eighth pure metal layer 3012-621 in the second welding layer 3012-62 and the sixth pure metal layer 301-621 of the first welding layer 301-62, the second welding layer The ninth pure metal layer 3012-622 in 3012-62 and the seventh pure metal layer 301-622 of the first welding layer 301-62 are respectively pure metal layers formed of the same pure metal. For example, as mentioned above, the sixth pure metal layer The pure metal layers 301-621 and the eighth pure metal layer 3012-621 may be Sn metal layers, and the seventh pure metal layer 301-622 and the ninth pure metal layer 3012-622 may be In metal layers. However, in this optional embodiment, as shown in Figure 8, the eighth pure metal layer 3012-621 and the ninth pure metal layer 3012-622 in the second welding layer 3012-62 are different from those in the first welding layer 301-62. The stacking sequence of the sixth pure metal layer 301-621 and the seventh pure metal layer 301-622 is different, that is, as shown in Figures 6a and 9, in the direction gradually away from the ohmic contact layer 301-61, the first welding layer 301 -62 stacks the sixth pure metal layer 301-621 and the seventh pure metal layer 301-622 in sequence, and the second welding layer 3012-62 stacks the ninth pure metal layer 3012-622 and the eighth pure metal layer 3012 in sequence- 621. The stacking sequence of multiple pure metal layers can also meet the requirements of different bonding temperatures, while increasing the design flexibility of the electrode structure 301-6.

As mentioned above, the multi-layer metal layers in the first welding layer 301-62 and the second welding layer 3012-62 are respectively pure metal layers formed of the same metal. It can be understood that according to the eutectic theory of metals, the first welding layer The layers 301-62 and the second welding layer 3012-62 may include pure metal layers formed of different metals. For example, the formation material of at least one pure metal layer in the second welding layer 3012-62 is different from the material in the first welding layer 301-62. The materials forming any pure metal layer are different. For example, the first soldering layer 301-62 includes a Sn layer and a Zn layer, and the second soldering layer 3012-62 includes a Sn layer and an In layer, or the first soldering layer 301- 62 includes an Ag layer and a Zn layer, while the second solder layer 3012-62 includes a Bi layer and a Sn layer. It is only necessary that the bonding temperature of the first soldering layers 301-62 and 301-62 is higher than the bonding temperature of the second soldering layers 3012-62 and 301-62.

In another optional embodiment of this embodiment, the first welding layer 301-62 and the second welding layer 3012-62 have different numbers of pure metal layers, and the first welding layer 301-62 and the second welding layer The pure metal layer of 3012-62 can be multiple layers of pure metal layers formed of the same pure metal or multiple layers of pure metal layers formed of different pure golds. As shown in Figure 9, the first welding layer 301-62 includes a sixth pure metal layer 301-621 and a seventh pure metal layer 301-622, and the second welding layer 3012-62 includes an eighth pure metal layer 3012-621, The ninth pure metal layer 3012-622 and the tenth pure metal layer 3012-623. In an optional embodiment, the sixth pure metal layer 301-621 and the seventh pure metal layer 301-622 may be Sn layer and Ag layer respectively, while the eighth pure metal layer 3012-621 and the ninth pure metal layer 3012- 622 and the tenth pure metal layers 3012-623 are Sn layer, In layer and Bi layer respectively.

In this embodiment, the pure metal layers in the first welding layer 301-62 and the second welding layer 3012-62 can also be selected from the combinations shown in Table 1 in Embodiment 1, and the stacking sequence can be changed according to actual needs. Moreover, it can be understood that the first welding layer 301-62 may include three or more pure metal layers, and similarly, the second welding layer 3012-62 may also include three or more pure metal layers, and the first welding layer 301-62 may include three or more pure metal layers. The multiple pure metal layers of the welding layer 301-62 and the second welding layer 3012-62 can be combined arbitrarily under the condition that the bonding temperature is met.

Embodiment 4

This embodiment provides a display panel. As shown in FIG. 10 , the display panel 400 of this embodiment includes a backplane 401 and a light-emitting element 402 located above the backplane 401 . As shown in FIG. 10 , the back plate 401 includes a first bonding pad 4011 and a second bonding pad 4012 formed on the back plate 401 . The light-emitting element 402 is the light-emitting element provided in Embodiment 3, that is, it includes the first light-emitting element 3011 fixed to the first pad 4011. The display panel 400 may further include at least one repair light emitting element 3012 fixed to at least one second pad 4012 . In this embodiment, the first light-emitting element 3011 and the repaired light-emitting element 3012 are welded to the backplane 401 through the welding process described in Embodiment 3 shown in FIG. 7 . The first light-emitting element 3011 is at the first bonding temperature, and the third alloy 301-63 formed after being heated by the first soldering layer 301-62 is fixed to the first bonding pad 4011. The repair light-emitting element 3012 is at the second bonding temperature. , the fourth alloy 301-64 formed after being heated by the second welding layer 3012-62 is fixed to the second bonding pad 4012. As mentioned above, the third alloy 301-63 is formed by heating the first welding layer 301-62, the fourth alloy 301-64 is formed by heating the second welding layer 3012-62, and the first welding layer 301-62 and the second soldering layer 3012-62 has the structural design described in Embodiment 3, therefore, the first bonding temperature is higher than the second bonding temperature. Therefore, the bonding process of repairing the light-emitting element 3012 will not affect the stability of the first light-emitting element 3011, thereby ensuring the overall yield of the display panel 400.

The above embodiments only illustrate the principles and effects of the present application, but are not used to limit the present application. Anyone familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed in this application shall still be covered by the claims of this application.

Industrial applicability

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Sequence Listing Free Content

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Claims

A backplate for bonding light-emitting elements, the surface of the backplate is provided with a first pad and a second pad for bonding light-emitting elements, and the second pad is used as a repair pad, wherein, The first bonding pad includes a first adhesive layer and a first bonding layer, the second bonding pad includes a second adhesive layer and a second bonding layer, the first bonding layer and the second bonding layer The bonding layers are all multi-layer structures, the multi-layer structure includes multiple pure metal layers, and the bonding temperature of the first bonding layer is higher than the bonding temperature of the second bonding layer.
The backplane of claim 1, wherein the first bonding layer and the second bonding layer have the same number of pure metal layers, or the first bonding layer and the second bonding layer have the same number of pure metal layers. Laminations have varying numbers of pure metal layers.
The backplane of claim 1 or 2, wherein the first bonding layer includes at least two layers of pure metal layers formed of different metals, and the second bonding layer includes at least two layers of pure metal layers formed of different metals. Pure metal layer.
The backplane of claim 3, wherein each of the first bonding layer and the second bonding layer includes alternately stacked multiple pure metal layers formed of a first metal and a second metal, and , the melting point of the first metal is higher than the melting point of the second metal.
The backplane of claim 4, wherein a thickness ratio of the pure metal layer formed by the first metal and the second metal is between 1:10 and 10:1.
The backplane of claim 5, wherein the pure metal layer formed by the first metal and the second metal has a first thickness ratio in the first bonding layer, and the first metal and the second metal have a first thickness ratio in the first bonding layer. The pure metal layer formed of the second metal has a second thickness ratio in the second bonding layer, and the first thickness ratio is greater than the second thickness ratio.
The backplane of claim 4, wherein the stacking order of the multiple pure metal layers in the first bonding layer and the second bonding layer is different.
The backplane of claim 3, wherein at least one of the plurality of pure metal layers in the second bonding layer is formed from a material different from the plurality of pure metal layers in the first bonding layer. The material forming any pure metal layer in the layer.
The backplane of claim 1 , wherein the orthogonal projected area of the first bonding layer on the surface of the backplane is 1 1.15~2.5 times; and/or, the orthogonal projected area of the second bonding layer on the surface of the back plate is 1.15~2.5 of the orthogonal projected area of the second bonding layer on the surface of the back plate. times.
The backplane of claim 1, wherein the first bonding pad further includes a first connection electrode located on a side of the first adhesive layer facing away from the first bonding layer; The orthographic projection area of the junction layer on the surface of the backplane is 1.15 to 2.5 times the orthographic projection area of the first connection electrode on the surface of the backplane; and/or the second pad layer further includes A second connection electrode located on the side of the second adhesive layer facing away from the second bonding layer; the orthogonal projected area of the second adhesive layer on the surface of the back plate is the second connection electrode 1.15 to 2.5 times the orthographic projection area on the surface of the back plate.
A display panel including:

A backplane, a first bonding pad and a second bonding pad are formed on the backplane, wherein the first bonding pad includes a first adhesive layer and a first alloy, and the second bonding pad includes a second bonding layer. layer and a second bonding layer, the second bonding layer is a multi-layer structure, the multi-layer structure includes multiple pure metal layers; and

A light-emitting element fixed on the backplane, the light-emitting element includes a first light-emitting element, the first light-emitting element is welded to the first pad through the first alloy, and the first alloy begins to melt The temperature is higher than the bonding temperature of the second bonding layer.
The display panel according to claim 11, wherein the light-emitting element further includes a repaired light-emitting element, and the repaired light-emitting element is welded to at least one of the second pads through a second alloy.
The display panel according to claim 11, wherein the light-emitting element includes:

A semiconductor structure, the semiconductor structure including a first semiconductor layer with opposite conductivity types, a second semiconductor layer, and a light-emitting layer located between the first semiconductor layer and the second semiconductor layer;

An electrode structure includes a first electrode and a second electrode, the first electrode is conductively connected to the first semiconductor layer, the second electrode is conductively connected to the second semiconductor layer, and the light-emitting element is connected through the electrode The structure is welded to the backing plate.
The display panel according to claim 11, wherein the orthogonal projected area of the second bonding layer on the surface of the back plate is 1 1.15~2.5 times.
A light-emitting element for a display panel. The light-emitting element is divided into a first light-emitting element and a repair light-emitting element used to replace the first light-emitting element that cannot light up normally in the display panel. The light-emitting element includes A semiconductor structure and an electrode structure formed on the surface of the semiconductor structure. The electrode structure of the first light-emitting element includes a first welding layer. The electrode structure of the repaired light-emitting element includes a second welding layer. The first welding layer and The second welding layer is a multi-layer structure, the multi-layer structure includes multiple pure metal layers, and the bonding temperature of the first welding layer is higher than the bonding temperature of the second welding layer.