A light emitting device

Abstract

The application provides a light emitting device, belonging to the technical field of semiconductor, comprising a light emitting chip, an expansion pad and a packaging adhesive layer with a multi-layer structure. The light emitting chip comprises an upper surface and a bottom surface, and the bottom surface is provided with a chip electrode. The upper surface of the expansion pad is in contact with the chip electrode and forms an electrical connection. The area of the orthographic projection of the expansion pad on the plane where the bottom surface of the light emitting chip is located is greater than the area of the orthographic projection of the chip electrode on the plane where the bottom surface of the light emitting chip is located. The packaging adhesive layer covers and wraps the light emitting chip, the chip electrode and the expansion pad, and exposes the bottom surface of the expansion pad; the orthographic projection of the expansion pad on the plane where the bottom surface of the light emitting chip is located is within the boundary line of the orthographic projection of the packaging adhesive layer on the plane where the bottom surface of the light emitting chip is located. The technical scheme of the application can effectively reduce the mounting difficulty of the light emitting device, improve the die bonding thrust, enhance the heat dissipation effect, and improve the adhesion between the packaging adhesive layer and the expansion pad.

Description

Technical Field

[0001] This application and the field of semiconductor technology particularly relate to a light-emitting device. Background Technology

[0002] LEDs are small in size, have good luminous efficiency, long lifespan, and excellent driving characteristics. Therefore, in recent years, they have been widely used as backlights and lighting sources for color display devices.

[0003] With the development of LED displays, CSP (Chip Scale Package) products have become a trend. In a conventional CSP packaging structure, such as... Figure 1 The encapsulating adhesive layer 30 wraps the light-emitting chip 10, and the chip electrode 11 of the light-emitting chip 10 is the pad of the entire light-emitting device. The mounting can only rely on the chip electrode 11 of the light-emitting chip 10, which results in insufficient die-bonding force when the light-emitting device is mounted on the substrate, making the mounting difficult.

[0004] In some existing technologies, such as Figure 2 As shown, a metal sheet 100 is added below the original light-emitting device. The upper surface of the metal sheet 100 is connected to the chip electrode 11 of the light-emitting chip 10. The spacing between the metal sheets 100 below the two chip electrodes 11 is increased, which can relatively reduce the difficulty of mounting and die bonding. However, since only a small part of the upper surface of the metal sheet 100 contacts the encapsulating adhesive layer 30 in addition to contacting the chip electrode 10, the contact area is small and the adhesion is poor. This may cause the metal sheet 100 to peel off from the encapsulating adhesive layer 30, further affecting the stability of the metal sheet 100. It may also cause the connection between the metal sheet 100 and the chip electrode 11 to loosen, affecting the mounting and normal function of the light-emitting device, and thus affecting the lifespan of the light-emitting device. Summary of the Invention

[0005] The purpose of this application is to provide a light-emitting device that can effectively reduce the mounting difficulty of the light-emitting device, increase the die-bonding force, improve the heat dissipation effect, and improve the adhesion between the encapsulation adhesive layer and the extended pad.

[0006] A light-emitting device includes a light-emitting chip, extended pads, and an encapsulating adhesive layer. The light-emitting chip includes an upper surface and a bottom surface, with chip electrodes disposed on the bottom surface. The upper surface of the extended pads contacts the chip electrodes and forms an electrical connection. The orthographic projection area of ​​the extended pads onto the plane containing the bottom surface of the light-emitting chip is larger than the orthographic projection area of ​​the chip electrodes onto the plane containing the bottom surface of the light-emitting chip. The encapsulating adhesive layer covers and encapsulates the light-emitting chip, the chip electrodes, and the extended pads, exposing the bottom surface of the extended pads; the orthographic projection of the extended pads onto the plane containing the bottom surface of the light-emitting chip is within the boundary line of the orthographic projection of the encapsulating adhesive layer onto the plane containing the bottom surface of the light-emitting chip.

[0007] In one feasible embodiment, the encapsulating adhesive layer includes a first adhesive layer and a second adhesive layer. The first adhesive layer covers and encapsulates the upper surface and sidewalls of the light-emitting chip, exposing the bottom surface of the chip electrodes to contact the upper surface of the extended pads. The second adhesive layer covers and encapsulates the sidewalls of the extended pads, filling the gaps between the chip electrodes and the extended pads at the bottom of the light-emitting chip, and exposing the bottom surface of the extended pads. The upper surface of the second adhesive layer is bonded to the bottom surface of the first adhesive layer to form a continuous structure. The hardness of the second adhesive layer is greater than that of the first adhesive layer but less than that of the extended pads.

[0008] In one feasible embodiment, the sidewalls of the first adhesive layer are flush with those of the second adhesive layer.

[0009] In one feasible embodiment, the first adhesive layer includes an upper adhesive layer and a sidewall adhesive layer. The upper adhesive layer covers the upper surface of the light-emitting chip and is a wavelength conversion layer or a reflective layer. The sidewall adhesive layer wraps around the sidewall of the light-emitting chip and is a wavelength conversion layer, a reflective layer, or a combination of a wavelength conversion layer and a reflective layer.

[0010] In one feasible embodiment, the extended pad includes at least one metal layer; when the extended pad includes one metal layer, the metal layer is formed on the chip electrode and electrically connected to the chip electrode; when the extended pad includes two or more metal layers, one metal layer is formed on the chip electrode and electrically connected to the chip electrode, and the remaining metal layers are sequentially formed on the previous metal layer and electrically connected to it.

[0011] In one feasible embodiment, the extended pad comprises two sequentially stacked metal layers, a first metal layer and a second metal layer. The first metal layer is formed on the chip electrode, contacting and electrically connecting to the chip electrode. The second metal layer is formed on the first metal layer, contacting and electrically connecting to the first metal layer, and the bottom surface of the second metal layer is the bottom surface of the extended pad.

[0012] In one feasible embodiment, the chip electrode includes a first electrode and a second electrode; a first metal layer and a second metal layer are sequentially stacked on the underside of the first electrode; and a first metal layer and a second metal layer are sequentially stacked on the underside of the second electrode.

[0013] In one feasible embodiment, the spacing between the two first metal layers is greater than or equal to the spacing between the first electrode and the second electrode; the spacing between the two second metal layers is greater than the spacing between the two first metal layers.

[0014] In one feasible embodiment, the extended pad comprises at least two sequentially stacked and electrically connected metal layers: the upper surface of the uppermost metal layer forms an electrical connection with the chip electrode; the bottom surface of the lowermost metal layer is the bottom surface of the extended pad; the surface area of ​​the bottom surface of each metal layer increases sequentially in the direction away from the chip electrode; and all metal layers are stacked to form a stepped structure.

[0015] In one feasible embodiment, the chip electrode includes a first electrode and a second electrode; the extended pad includes a first extended pad and a second extended pad; the metal layer includes a first metal extension layer and a second metal extension layer; the step structure includes a first step structure and a second step structure; the first extended pad includes at least two sequentially stacked and electrically connected first metal extension layers, with the outer side of the stacked first metal extension layers forming a first step structure; the second extended pad includes at least two sequentially stacked and electrically connected second metal extension layers, with the outer side of the stacked second metal extension layers forming a second step structure. That is, the first step structure and the second step structure are located on the side of the first extended pad and the second extended pad that are far apart from each other.

[0016] In one feasible embodiment, the spacing between the first metal extension layers increases sequentially in the direction away from the chip electrode.

[0017] In one feasible approach, the distance between the boundary line of the orthographic projection of the extended pad onto the plane containing the bottom surface of the light-emitting chip and the boundary line of the orthographic projection of the encapsulating adhesive layer onto the plane containing the bottom surface of the light-emitting chip is 1–300 μm.

[0018] In one feasible embodiment, the bottom surface of the first adhesive layer is flush with the bottom surface of the chip electrode; the light-emitting device further includes a coupling agent layer, which is disposed between the contact surface of the extended pad and the chip electrode, between the contact surface of the upper surface of the extended pad and the first adhesive layer, between the contact surface of the first adhesive layer and the second adhesive layer, and between the contact surface of the second adhesive layer and the bottom of the light-emitting chip.

[0019] In one feasible embodiment, the bottom surface of the first adhesive layer is higher than the bottom surface of the chip electrode; the light-emitting device also includes a coupling agent layer, which is disposed between the extended pad and the chip electrode, between the first adhesive layer and the second adhesive layer, and between the second adhesive layer and the contact surface of the bottom of the light-emitting chip.

[0020] In one feasible embodiment, each metal layer includes a seed layer and an extended electrode layer formed on the seed layer.

[0021] In one feasible embodiment, at least one of the metal layers further includes a protective layer formed on the extended electrode layer.

[0022] Compared with the prior art, the beneficial effects of this application include at least the following:

[0023] In the technical solution of this application, the extended pad is equivalent to extending the inherent chip electrodes of the light-emitting chip itself, which increases the mounting area, improves the die bonding force, reduces the mounting difficulty, and also improves the heat dissipation effect.

[0024] Meanwhile, since the encapsulating adhesive layer not only wraps around the light-emitting chip but also around the extended pads, it improves the adhesion between the extended pads and the encapsulating adhesive layer, making it less likely for the extended pads to peel off from the encapsulating adhesive layer. This improves the stability of the extended pads, minimizing the possibility of loosening, and consequently ensuring a more stable connection between the extended pads and the chip electrodes. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic cross-sectional view of a conventional light-emitting device in the prior art;

[0027] Figure 2 A cross-sectional structural diagram of a light-emitting device with an added metal sheet in the prior art;

[0028] Figure 3 This is a schematic cross-sectional view of a light-emitting device according to an embodiment of this application;

[0029] Figure 4 This is a top view schematic diagram of a light-emitting device according to an embodiment of this application;

[0030] Figure 5 This is a schematic cross-sectional view of a light-emitting device having two flush adhesive layers on its sidewalls, according to an embodiment of this application.

[0031] Figure 6 This is a schematic cross-sectional view of a light-emitting device having two uneven adhesive layers on its sidewalls, according to an embodiment of this application.

[0032] Figure 7 This is a schematic cross-sectional view of a light-emitting device with two metal layer extended pads according to an embodiment of this application;

[0033] Figure 8This is a schematic cross-sectional view of another light-emitting device with two metal layer extended pads according to an embodiment of this application;

[0034] Figure 9 This is a schematic cross-sectional view of a light-emitting device with stepped extended pads according to an embodiment of this application.

[0035] Figure 10 This is a schematic cross-sectional view of another light-emitting device with stepped extended pads according to an embodiment of this application;

[0036] Figure 11 This is a schematic cross-sectional view of a light-emitting device with different encapsulating adhesive layer structures according to an embodiment of this application;

[0037] Figure 12 A cross-sectional schematic diagram of the light-emitting device to show the local structure of a single-layer metal layer;

[0038] Figure 13 and Figure 14 A cross-sectional schematic diagram of the light-emitting device to show two different local structures of the double-layer metal layer.

[0039] In the diagram: 10, Light-emitting chip; 11, Chip electrode; 111, First electrode; 112, Second electrode; 20, Extended pad; 201, First extended pad; 202, Second extended pad; 21, First metal layer; 22, Second metal layer; 211, Seed layer; 212, Extended electrode layer; 213, Protective layer; 231, First metal extension layer; 232, Second metal extension layer; 24, Step structure; 241, First step structure; 242, Second step structure; 30, Encapsulating adhesive layer; 31, First adhesive layer; 311, Top adhesive layer; 312, Sidewall adhesive layer; 32, Second adhesive layer; 40, Coupling agent layer; 100, Metal sheet. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0041] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0042] It should be noted that the terms "upper surface" and "bottom surface" in this application are relative to the horizontal placement of the flip-chip, and are expressions based on relative orientation, and do not constitute an absolute limitation.

[0043] It should be further noted that the technical features of all the embodiments described below can be combined with each other without conflict.

[0044] Example 1:

[0045] like Figure 3 and Figure 4 As shown, this embodiment provides a light-emitting device, which includes a flip-chip light-emitting chip 10, an extended pad 20, and an encapsulating adhesive layer 30 with a multilayer structure.

[0046] The light-emitting chip 10 includes an upper surface and a bottom surface. A chip electrode 11 is disposed on the bottom surface; the chip electrode 11 can also be understood as the inherent electrode pads of the light-emitting chip 10 itself. The extended pad 20 includes an upper surface and a bottom surface. The upper surface of the extended pad 20 contacts the chip electrode 11 and forms an electrical connection. The surface area of ​​the bottom surface of the extended pad 20 is larger than the exposed area of ​​the chip electrode 11; that is, the orthographic projection area of ​​the extended pad 20 onto the plane containing the bottom surface of the light-emitting chip 10 is larger than the orthographic projection area of ​​the chip electrode 11 onto the plane containing the bottom surface of the light-emitting chip 10. The encapsulating adhesive layer 30 covers and encapsulates the light-emitting chip 10, the chip electrode 11, and the extended pad 20, exposing the bottom surface of the extended pad 20. The orthographic projection of the extended pad 20 onto the plane containing the bottom surface of the light-emitting chip 10 is within the boundary line of the orthographic projection of the encapsulating adhesive layer 30 onto the plane containing the bottom surface of the light-emitting chip 10.

[0047] It should be noted that the chip electrode 11 includes a first electrode 111 and a second electrode 112, and the corresponding extended pad 20 includes a first extended pad 201 connected to the first electrode 111 and a second extended pad 202 connected to the second electrode 112. The N electrode (first electrode 111) pad and the P electrode (second electrode 112) pad have the same height and are spaced apart by a predetermined distance. The first extended pad 201 and the second extended pad 202 of the extended pad 20 have the same thickness and are also spaced apart by a predetermined distance, thereby ensuring an insulating gap.

[0048] It should be further explained that the orthographic projection of the extended pad 20 onto the bottom surface of the light-emitting chip 10 refers to the orthographic projection of both parts of the extended pad 20 onto the bottom surface of the light-emitting chip 10. The choice of projecting onto the bottom surface of the light-emitting chip 10 in the above scheme is merely to select the same projection plane for comparison of projected areas. Alternatively, the plane containing the upper surface of the light-emitting chip 10 could be chosen as the projection plane, or any plane parallel to the upper or bottom surface of the light-emitting chip 10 could be chosen as the projection plane.

[0049] In the technical solution of this embodiment, the extended pad 20 is equivalent to extending the inherent chip electrode 11 of the light-emitting chip 10 itself, increasing the area of ​​the mounting surface, improving the die bonding force, reducing the mounting difficulty, and also improving the heat dissipation effect.

[0050] Furthermore, the encapsulating adhesive layer 30 not only wraps around the light-emitting chip 10, but also around the perimeter of the extended pad 20. This improves the adhesion between the extended pad 20 and the encapsulating adhesive layer 30, making it less likely for the extended pad 20 to peel off from the encapsulating adhesive layer 30. This enhances the stability of the extended pad 20, minimizing the possibility of loosening and ensuring a more stable connection between the extended pad 20 and the chip electrode 11.

[0051] Preferably, the distance between the boundary line of the orthographic projection of the extended pad 20 onto the bottom surface of the light-emitting chip 10 and the boundary line of the orthographic projection of the encapsulating adhesive layer 30 onto the bottom surface of the light-emitting chip 10 is 1-300μm, for example, it can be 5μm, 7μm, 8μm, 10μm, 20μm, 50μm, 100μm, 150μm, 200μm, 250μm, etc. To achieve stable adhesion, a smaller value should be selected as much as possible. While the encapsulating adhesive layer 30 can wrap around the extended pad 20, the overall size of the light-emitting device can be controlled as much as possible to prevent it from becoming too large.

[0052] Since different materials have different adhesive properties when in contact, in one embodiment, the encapsulating adhesive layer 30 can have a multi-layer structure. For example, different adhesive materials are used to bond the encapsulating adhesive layer 30 to different positions in contact with the light-emitting chip 10, the chip electrode 11, and the extended pad 20, so as to achieve the treatment of the differences between the materials. This allows the encapsulating adhesive layer 30 to achieve a better adhesion effect to the light-emitting chip 10, the chip electrode 11, and the extended pad 20, so as to extend the time when the contact point can be separated as much as possible, thereby increasing the service life.

[0053] In a more preferred solution, such as Figures 3 to 10 As shown, the encapsulating adhesive layer 30 may include a first adhesive layer 31 and a second adhesive layer 32. The first adhesive layer 31 covers and wraps around the upper surface and sidewalls of the light-emitting chip 10, exposing the bottom surface of the chip electrode 11 of the light-emitting chip 10 to contact the upper surface of the extended pad 20. The second adhesive layer 32 covers and wraps around the extended pad 20, filling the gaps between the lower chip electrodes 11 of the light-emitting chip 10 and between the extended pads 20, exposing the bottom surface of the extended pad 20. At the same time, the upper surface of the second adhesive layer 32 is bonded to the bottom surface of the first adhesive layer 31 to form a continuous structure.

[0054] In one embodiment, the first adhesive layer 31 and the second adhesive layer 32 can be adhesive layers made of the same material, such as wavelength conversion layers, for example, fluorescent adhesive layers.

[0055] However, in the preferred embodiment, the hardness of the second adhesive layer 32 is greater than that of the first adhesive layer 31, but less than that of the extended pad 20. Therefore, the second adhesive layer 32 plays two roles: firstly, it can form a wrap around the extended pad 20, making the extended pad 20 less prone to loosening and more stable; secondly, as a transition layer between the first adhesive layer 31 and the extended pad 20, it reduces the hardness difference between the layers, which helps to improve the adhesion between the layers.

[0056] When a very soft material layer is bonded to a relatively hard material layer, the softer layer deforms more easily during deformation due to the significant difference in hardness, while the harder layer deforms less easily. This can lead to a large relative displacement at the contact surface, resulting in reduced adhesion. This application utilizes a second adhesive layer 32 as a transition layer between the first adhesive layer 31 and the extended pad 20. By reducing the hardness difference between the material layers, the relative displacement during deformation is reduced, lowering the risk of detachment and thus improving adhesion.

[0057] To increase the hardness of the second adhesive layer 32, a curing agent can be added to the manufacturing material. Other methods will not be listed here.

[0058] For example, the first adhesive layer 31 can be a wavelength conversion adhesive layer to perform wavelength conversion. The second adhesive layer 32 can be a wavelength conversion layer doped with a curing agent, a reflective layer, or one of a silicone resin layer, a silicone rubber layer, or an epoxy resin layer.

[0059] like Figure 5 As shown, it is preferable that the sidewalls of the first adhesive layer 31 and the second adhesive layer 32 are flush. On the one hand, this can increase the contact area between the first adhesive layer 31 and the second adhesive layer 32, thereby increasing adhesion; on the other hand, it can reduce the exposed area of ​​the second adhesive layer 32, thereby reducing dust accumulation and lowering the failure rate.

[0060] In some implementation schemes, such as Figure 6 As shown, the sidewalls of the first adhesive layer 31 and the second adhesive layer 32 may not be flush.

[0061] Furthermore, such as Figure 11As shown, the first adhesive layer 31 may include an upper adhesive layer 311 and a sidewall adhesive layer 312. The upper adhesive layer 311 covers the upper surface of the light-emitting chip 10 and may be a wavelength conversion adhesive layer or a reflective layer. The sidewall adhesive layer 312 wraps around the sidewalls of the light-emitting chip 10 and may be a wavelength conversion layer, a reflective layer, or a combination of both. When the sidewall adhesive layer 312 is a reflective layer, the upper part of the sidewall adhesive layer 312 may be as follows: Figure 12 The bowl shape shown can also be extended vertically upwards to achieve a better reflective effect.

[0062] In this embodiment, as Figure 3 As shown, each extended pad 20 may include only a first metal layer 21, which is formed on the chip electrode 11 and electrically connected to the chip electrode 11.

[0063] In this embodiment, as Figure 5 As shown, the bottom surface of the first adhesive layer 31 can be flush with the bottom surface of the chip electrode 11; the light-emitting device also includes a coupling agent layer 40, which is disposed between the contact surface of the extended pad 20 and the chip electrode 11, between the contact surface of the upper surface of the extended pad 20 and the first adhesive layer 31, between the contact surface of the first adhesive layer 31 and the second adhesive layer 32, and between the contact surface of the second adhesive layer 32 and the bottom of the light-emitting chip 10. The coupling agent layer 40 serves as an intermediate layer, enhancing the adhesion between the layers.

[0064] In this embodiment, as Figure 3 As shown, the bottom surface of the first adhesive layer 31 is higher than the bottom surface of the chip electrode 11. A coupling agent layer 40 is disposed between the extended pad 20 and the chip electrode 11. A coupling agent layer 40 is disposed between the first adhesive layer 31 and the second adhesive layer 32. A coupling agent layer 40 is disposed between the second adhesive layer 32 and the contact surface at the bottom of the light-emitting chip 10. The coupling agent layer 40 serves as an intermediate layer, enhancing the adhesion between the layers.

[0065] The thickness of the coupling agent layer 40 is preferably less than 1 μm, and the coupling agent layer can be an organic material to enhance the adhesion between the organic material and the inorganic material.

[0066] In this embodiment, as Figure 12 As shown, the first metal layer 21 includes a seed layer 211 and an extended electrode layer 212 formed on the seed layer 211. Since this embodiment only has a first metal layer 21, the bottom surface of which is the mounting surface, the first metal layer 21 may also include a protective layer 213, which is formed on the extended electrode layer 212. The protective layer 213 is typically nickel-gold, forming a protective layer on the bottom surface of the first metal layer 21 to minimize oxidation of the bottom surface.

[0067] Example 2:

[0068] Figure 1 When the light-emitting device is mounted on the substrate, the chip electrode 11 is the electrode pad of the entire light-emitting device, and heat dissipation can only rely on the chip electrode 11. Since the distance between the first electrode 111 and the second electrode 112 of the chip electrode 11 is small, and the gap between the chip electrode 11 and the substrate is also small, the heat dissipation effect is poor. Figure 2 The metal sheet 100 of the light-emitting device can slightly increase the gap between the light-emitting device and the substrate, but the heat dissipation effect is not obvious.

[0069] Therefore, as Figure 7 and Figure 8 As shown, this embodiment provides a light-emitting device that can improve heat dissipation. The difference between this embodiment 2 and embodiment 1 is that the extended pad 20 of the light-emitting device in this embodiment includes two metal layers stacked in sequence, namely a first metal layer 21 and a second metal layer 22, while the extended pad 20 in embodiment 1 only has a first metal layer 21.

[0070] In this embodiment, as Figure 7 and Figure 8 As shown, a first metal layer 21 is formed on the chip electrode 11 and is electrically connected to the chip electrode 11. A second metal layer 22 is formed on the first metal layer 21 and is electrically connected to the lower surface of the first metal layer 21. The bottom surface of the second metal layer 22 is the bottom surface of the extended pad 20.

[0071] When mounted onto the substrate, the first metal layer 21 and the second metal layer 22 effectively increase the height, thus increasing the height between the light-emitting chip 10 and the substrate, which helps to improve the heat dissipation effect.

[0072] like Figure 8 As shown, the chip electrode 11 includes a first electrode 111 and a second electrode 112; a first metal layer 21 and a second metal layer 22 are sequentially stacked on the underside of the first electrode 111; a first metal layer 21 and a second metal layer 22 are sequentially stacked on the underside of the second electrode 112. The spacing between the two first metal layers 21 is greater than or equal to the spacing between the first electrode 111 and the second electrode 112, and the spacing between the two second metal layers 22 is greater than the spacing between the two first metal layers 21. This is equivalent to increasing the spacing between the electrodes of the light-emitting device. On the one hand, it increases the insulation interval, which can reduce the risk of short circuits, improve circuit safety, and reduce the difficulty of mounting. On the other hand, the increased spacing between the electrodes also helps to improve the heat dissipation effect.

[0073] Preferably, the thickness of the first metal layer 21 is 10μm to 100μm, and the thickness of the second metal layer 22 is 10μm to 100μm. For example, values ​​such as 10μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, and 100μm can be selected.

[0074] The first metal layer 21 is mainly used to appropriately increase the electrode height and improve the heat dissipation effect. Therefore, the thickness of the first metal layer 21 can be selected as large as possible within a reasonable range. At the same time, the surface area of ​​the upper and lower surfaces of the first metal layer 21 can be the same as or different from the surface area of ​​the original chip electrode 11, and no specific requirements are made.

[0075] The second metal layer 22 is mainly used to increase the mounting area, increase the electrode spacing, reduce the mounting difficulty, and improve the die bonding force. Therefore, the area of ​​the bottom surface of the second metal layer 22 should be larger than the surface area of ​​the chip electrode 11. There are no specific requirements for the thickness of the second metal layer 22. However, under the principle of reducing the volume of the entire light-emitting device, the thickness of the second metal layer 22 can be selected as small as possible within a reasonable range.

[0076] In one design, the thickness of the first metal layer 21 is greater than or equal to the thickness of the second metal layer 22. For example, the thickness of the first metal layer 21 can be selected within the range of 40μm to 100μm, and the thickness of the second metal layer 22 can be selected within the range of 10μm to 40μm. Alternatively, the thickness of the first metal layer 21 can be selected within the range of 20μm to 50μm, and the thickness of the second metal layer 22 can be selected within the range of 10μm to 20μm. Furthermore, the thicknesses of the first metal layer 21 and the second metal layer 22 can be the same, for example, both 10μm, 20μm, or 30μm. Increasing the thickness of the second metal layer 22 can also improve the heat dissipation effect to some extent.

[0077] In a preferred embodiment, the total thickness of the first metal layer 21 and the second metal layer 22 does not exceed 200 μm, and preferably does not exceed 80 μm.

[0078] Both the first metal layer 21 and the second metal layer 22 can be material layers composed of one or more metals selected from titanium, chromium, copper, nickel, palladium, and gold.

[0079] In this embodiment, as Figure 13As shown, the bottom surface of the first metal layer 21 is in complete contact with the upper surface of the second metal layer 22, so the bottom surface of the first metal layer 21 is not exposed to the outside. Therefore, the first metal layer 21 may only include the seed layer 211 and the extended electrode layer 212 formed on the seed layer 211. The bottom surface of the second metal layer 22 is the bottom surface of the extended pad 20, and therefore is exposed to the outside. Thus, the second metal layer 22 includes not only the seed layer 211 and the extended electrode layer 212 formed on the seed layer 211, but also a protective layer 213 formed on the extended electrode layer 212.

[0080] In this embodiment, as Figure 14 As shown, the bottom surface of the first metal layer 21 is in contact with the upper surface of the second metal layer 22, so the bottom surface of the first metal layer 21 is partially exposed. Therefore, in addition to the seed layer 211 and the extended electrode layer 212 formed on the seed layer 211, the first metal layer 21 preferably also includes a protective layer 213 formed on the extended electrode layer 212, which forms a protective layer on the bottom surface of the first metal layer 21.

[0081] Example 3:

[0082] The technical solution in Example 3 is also intended to further improve the heat dissipation effect.

[0083] Therefore, as Figure 9 As shown, this embodiment also provides a light-emitting device that can improve heat dissipation. The difference between this embodiment 3 and embodiment 1 or embodiment 2 is that the extended pad 20 of the light-emitting device in this embodiment includes at least two layers of metal layers stacked sequentially and electrically connected to each other. The upper surface of the uppermost metal layer is electrically connected to the chip electrode 11, and the bottom surface of the lowermost metal layer is the bottom surface of the extended pad 20. The surface area of ​​the bottom surface of all stacked metal layers increases sequentially in the direction away from the chip electrode 11; after all metal layers are stacked, a stepped structure 24 is formed.

[0084] In this embodiment, the stepped metal layer structure increases the gap height between the chip electrode 11 of the light-emitting device and the substrate, improving heat dissipation. Simultaneously, the stepped structure also increases the contact area between the metal layer and the adhesive layer, improving their adhesion.

[0085] In this embodiment, as Figure 10As shown, the chip electrode 11 includes a first electrode 111 and a second electrode 112; the extended pad 20 includes a first extended pad 201 and a second extended pad 202; the metal layer includes a first metal extended layer 231 and a second metal extended layer 232; and the stepped structure 24 includes a first stepped structure 241 and a second stepped structure 242. The first extended pad 201 includes at least two sequentially stacked and electrically connected first metal extended layers 231, with the outer side of the stacked first metal extended layers 231 forming a first stepped structure 241. The second extended pad 202 includes at least two sequentially stacked and electrically connected second metal extended layers 232, with the outer side of the stacked second metal extended layers 232 forming a second stepped structure 242.

[0086] like Figure 10 As shown, the first step structure 241 and the second step structure 242 are located on the side of the first extended pad 201 and the second extended pad 202 that are far apart from each other. This does not affect the spacing between the electrodes, and the adhesion can be improved by the contact between the basically symmetrical step structure and the encapsulating adhesive layer 30.

[0087] Preferably, such as Figure 10 As shown, in the direction away from the chip electrode 11, the spacing between the first metal extension layer 231 and the second metal extension layer 232 increases sequentially, while the spacing between the first metal extension layer 231 and the second metal extension layer 232, which are closest to the chip electrode 11, is greater than or equal to the spacing between the first electrode 111 and the second electrode 112.

[0088] The spacing between the first metal extension layer 231 and the second metal extension layer 232 increases sequentially, which is equivalent to increasing the spacing between the electrodes of the light-emitting device. On the one hand, the increased insulation spacing can reduce the risk of short circuits, improve circuit safety, and reduce the difficulty of mounting. On the other hand, the increased spacing between the electrodes also helps to improve the heat dissipation effect.

[0089] The metal layers can be two, preferably at least three, and each layer can have the same or different thicknesses. Preferably, the thickness of each metal layer is greater than or equal to 0.5μm to 100μm, and can be selected from 0.5μm, 1μm, 1.5μm, 2μm, 10μm, 20μm, 25μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, etc. The total thickness of all metal extension layers 23 should preferably not exceed 300μm, and preferably not exceed 110μm.

[0090] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A light-emitting device, characterized in that, include: A light-emitting chip has an upper surface and a bottom surface, wherein chip electrodes are disposed on the bottom surface; An extended pad has its upper surface in contact with the chip electrode to form an electrical connection; the projected area of ​​the extended pad on the plane where the bottom surface of the light-emitting chip is located is larger than the projected area of ​​the chip electrode on the plane where the bottom surface of the light-emitting chip is located. A multi-layer encapsulating adhesive layer covers and encapsulates the light-emitting chip, the chip electrode, and the extended pad, exposing the bottom surface of the extended pad; the orthographic projection of the extended pad onto the plane containing the bottom surface of the light-emitting chip is within the boundary line of the orthographic projection of the encapsulating adhesive layer onto the plane containing the bottom surface of the light-emitting chip; The chip electrode includes a first electrode and a second electrode; The extended pads include a first extended pad disposed below the first electrode and a second extended pad disposed below the second electrode; both the first and second extended pads include at least two metal layers; The first extended pad includes at least two first metal extended layers that are stacked sequentially and electrically connected to each other; The second extended pad includes at least two second metal extension layers that are stacked sequentially and electrically connected to each other; In the direction away from the chip electrode, the spacing between the first metal extension layer and the second metal extension layer at the same height increases sequentially; The spacing between the first metal extension layer and the second metal extension layer, which are closest to the chip electrode, is greater than or equal to the spacing between the first electrode and the second electrode. Furthermore, the outer side of all the first metal extension layers stacked together has a first step structure; The outer side of all the second metal extension layers stacked together has a second step structure; The encapsulating adhesive layer includes: The first adhesive layer covers and wraps the upper surface and sidewalls of the light-emitting chip, and exposes the bottom surface of the chip electrode of the light-emitting chip to contact the upper surface of the extended pad. The second adhesive layer covers and wraps the sidewalls of the extended pads, fills the gaps between the chip electrodes and the extended pads at the bottom of the light-emitting chip, and exposes the bottom surface of the extended pads. The upper surface of the second adhesive layer is bonded to the bottom surface of the first adhesive layer to form a continuous structure. The hardness of the second adhesive layer is greater than that of the first adhesive layer, but less than that of the extended pad.

2. The light-emitting device according to claim 1, characterized in that, The sidewalls of the first adhesive layer and the second adhesive layer are flush.

3. The light-emitting device according to claim 1, characterized in that, The first adhesive layer includes: An adhesive layer covers the upper surface of the light-emitting chip; the adhesive layer is a wavelength conversion layer or a reflective layer. A sidewall adhesive layer that wraps around the sidewall of the light-emitting chip, wherein the sidewall adhesive layer is a wavelength conversion layer, a reflective layer, or a combination of a wavelength conversion layer and a reflective layer.

4. The light-emitting device according to claim 1, characterized in that, The extended pad includes two metal layers stacked sequentially, namely a first metal layer and a second metal layer; the thickness of the first metal layer is greater than the thickness of the second metal layer.

5. The light-emitting device according to claim 1, characterized in that, In the direction away from the chip electrode, the surface area of ​​the bottom surface of each metal layer increases sequentially.

6. The light-emitting device according to any one of claims 1-5, characterized in that, The distance between the boundary line of the orthographic projection of the extended pad onto the plane containing the bottom surface of the light-emitting chip and the boundary line of the orthographic projection of the encapsulating adhesive layer onto the plane containing the bottom surface of the light-emitting chip is 1 to 300 μm.

7. The light-emitting device according to any one of claims 1-5, characterized in that, The bottom surface of the first adhesive layer is flush with the bottom surface of the chip electrode; The light-emitting device further includes a coupling agent layer, which is disposed between the contact surfaces of the extended pad and the chip electrode, between the contact surfaces of the upper surface of the extended pad and the first adhesive layer, between the contact surfaces of the first adhesive layer and the second adhesive layer, and between the contact surfaces of the second adhesive layer and the bottom of the light-emitting chip.

8. The light-emitting device according to any one of claims 1-5, characterized in that, The bottom surface of the first adhesive layer is higher than the bottom surface of the chip electrode; The light-emitting device further includes a coupling agent layer, which is disposed between the extended pad and the chip electrode, between the first adhesive layer and the second adhesive layer, and between the second adhesive layer and the contact surface of the bottom of the light-emitting chip.

9. The light-emitting device according to any one of claims 1-5, characterized in that, Each of the metal layers includes a seed layer and an extended electrode layer formed on the seed layer.

10. The light-emitting device according to claim 9, characterized in that, Of all the metal layers, at least one of the metal layers further includes a protective layer formed on the extended electrode layer.

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