Substrateless light emitting device and method of making the same

Abstract

The present disclosure provides a substrate-free light-emitting device and a preparation method thereof, and belongs to the technical field of optoelectronic manufacturing. The light-emitting device comprises a cover layer, a support layer and a plurality of light-emitting structures, the cover layer covers the plurality of light-emitting structures, and the support layer is located in the support layer. By setting the cover layer, the plurality of light-emitting structures are connected into one by covering the plurality of light-emitting structures with the cover layer. By setting the support layer in the cover layer, the relative positions between the plurality of light-emitting structures can be kept unchanged by providing support with the support layer, so that the substrate is not needed to provide support, thereby avoiding the influence of the substrate on the light-emitting angle and being conducive to improving the display effect.

Description

Technical Field

[0001] This disclosure relates to the field of optoelectronic manufacturing technology, and in particular to a substrate-free light-emitting device and its fabrication method. Background Technology

[0002] Light-emitting diodes (LEDs) are highly influential new products in the optoelectronics industry. They are characterized by their small size, long lifespan, rich and colorful colors, and low energy consumption, and are widely used in display devices.

[0003] Miniature LED chips are small in size, and sometimes multiple miniature LED chips are made together during manufacturing. For example, when making display panels, red, green and blue chips can be made together to form a three-color light-emitting device.

[0004] In this type of light-emitting device, multiple miniature light-emitting diode (LED) chips are typically mounted on a substrate, with the light-emitting surface being the surface of the substrate furthest from the LED chips. Because the substrate has a certain thickness and a relatively high refractive index, the light emitted by the LED chips changes its propagation direction after passing through the substrate, resulting in a larger emission angle and ultimately affecting the display effect. Summary of the Invention

[0005] This disclosure provides a substrate-free light-emitting device and its fabrication method, which avoids the problem of increased emission angle caused by the substrate. The technical solution is as follows: In a first aspect, embodiments of this disclosure provide a substrate-free light-emitting device, which includes a cover layer, a support layer, and a plurality of light-emitting structures, wherein the cover layer covers the plurality of light-emitting structures and the support layer is located within the support layer.

[0006] Optionally, the cover layer includes a first cover layer and a second cover layer, wherein the first cover layer covers the plurality of light-emitting structures, the second cover layer is located on the first cover layer, and the support layer is located within the second cover layer.

[0007] Optionally, the light-emitting device further includes a conductive layer located on the surface of the first cover layer near the second cover layer, and one electrode of each of the plurality of light-emitting structures is electrically connected to the conductive layer through a via.

[0008] Optionally, the light-emitting device further includes a carrier layer, on which the plurality of light-emitting structures are located, and the cover layer covers the surface of the carrier layer.

[0009] Optionally, the support layer is a metal layer.

[0010] Optionally, the thickness of the support layer is 5μm to 20μm.

[0011] Secondly, embodiments of this disclosure also provide a method for fabricating the substrate-free light-emitting device described in the preceding aspect, the method comprising: Multiple light-emitting structures are formed on the substrate's bearing surface; A cover layer and a support layer are formed, wherein the cover layer covers the plurality of light-emitting structures and the support layer is located within the support layer; Remove the substrate.

[0012] Thirdly, embodiments of this disclosure also provide another substrate-free light-emitting device, which includes a first cover layer, a second cover layer, and a plurality of light-emitting structures, wherein the first cover layer covers the plurality of light-emitting structures, the second cover layer is located on the first cover layer, and the second cover layer is a rigid insulating layer.

[0013] Optionally, the second capping layer includes at least one of SiO2 or TiO2.

[0014] Fourthly, embodiments of this disclosure also provide a method for fabricating the substrate-free light-emitting device described in the preceding aspect, the method comprising: Multiple light-emitting structures are formed on the substrate's bearing surface; A first covering layer is formed, which covers the plurality of light-emitting structures; A second cover layer is formed, which is located on the first cover layer, and the second cover layer is a rigid insulating layer; Remove the substrate.

[0015] The beneficial effects of the technical solutions provided in this disclosure include at least the following: By setting a cover layer to cover multiple light-emitting structures and connecting them into one unit, and by setting a support layer within the cover layer to provide support, the relative positions between the multiple light-emitting structures can remain unchanged. This eliminates the need for a substrate to provide support, thus avoiding the influence of the substrate on the light emission angle and improving the display effect. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this disclosure, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1This is a schematic diagram of the structure of a light-emitting device provided in an embodiment of this disclosure; Figure 2 yes Figure 1 Top view; Figure 3 This is a schematic diagram of another substrate-free light-emitting device provided in an embodiment of this disclosure; Figure 4 This is a flowchart illustrating a method for fabricating a substrate-free light-emitting device according to an embodiment of this disclosure; Figure 5 This is a flowchart illustrating a method for fabricating a substrate-free light-emitting device according to an embodiment of this disclosure; Figure 6 This is a flowchart of a method for fabricating a substrate-free light-emitting device according to an embodiment of this disclosure. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this disclosure clearer, the embodiments of this disclosure will be described in further detail below with reference to the accompanying drawings.

[0019] Figure 1 This is a schematic diagram of the structure of a light-emitting device provided in an embodiment of this disclosure. Figure 1 As shown, the light-emitting device includes multiple light-emitting structures 20, a cover layer 30, and a support layer 40. The cover layer 30 covers the multiple light-emitting structures 20, and the support layer 40 is located inside the support layer 40.

[0020] By setting a cover layer 30, multiple light-emitting structures 20 are covered by the cover layer 30 and connected into one unit. By setting a support layer 40 inside the cover layer 30, the relative positions between the multiple light-emitting structures 20 can remain unchanged. This eliminates the need for a substrate to provide support, thus avoiding the influence of the substrate on the light emission angle and improving the display effect.

[0021] like Figure 1 As shown in the embodiments of this disclosure, the light-emitting device includes three light-emitting structures 20, which are arranged in a straight line. These three light-emitting structures 20 are a red light-emitting structure emitting red light, a red light-emitting structure emitting green light, and a red light-emitting structure emitting blue light, respectively.

[0022] The light-emitting structure 20 may include a first semiconductor layer, a light-emitting layer, and a second semiconductor layer. One of the first and second semiconductor layers may be an N-type semiconductor layer, and the other may be a P-type semiconductor layer. The light-emitting layer may include a multi-quantum-well layer. For light-emitting structures 20 of different colors, the materials of the first semiconductor layer, the light-emitting layer, and the second semiconductor layer may be different.

[0023] For example, the size of the light-emitting structure 20 can be 2 μm to 10 μm.

[0024] like Figure 1 As shown, the light-emitting device also includes a carrier layer 11, multiple light-emitting structures 20 are located on the carrier layer 11, and a cover layer 30 covers the surface of the carrier layer 11.

[0025] For example, the carrier layer 11 can be formed using an organic material, such as by spin coating. The thickness of the carrier layer 11 can be 3 μm to 30 μm.

[0026] The carrier layer 11 can connect multiple light-emitting structures 20, and since there is no substrate, the carrier layer 11 can also provide a certain degree of protection for the light-emitting structures 20.

[0027] like Figure 1 As shown, the cover layer 30 includes a first cover layer 31 and a second cover layer 32. The first cover layer 31 covers a plurality of light-emitting structures 20, the second cover layer 32 is located on the first cover layer 31, and the support layer 40 is located inside the second cover layer 32.

[0028] By setting the cover layer 30 as two layers, it is convenient to set up the corresponding structure to connect multiple light-emitting structures 20 for power supply. The first cover layer 31 and the second cover layer 32 can be made of different materials. The first cover layer 31 can be made of a material that can better cover the surface of the light-emitting structure 20 and avoid the formation of pores. The second cover layer 32 can be made of a more wear-resistant material to provide protection.

[0029] For example, both the first capping layer 31 and the second capping layer 32 can be formed of organic materials. The thickness of the first capping layer 31 can be 0.5 μm to 10 μm, and the thickness of the second capping layer 32 can be 0.5 μm to 10 μm. The thicknesses of the first capping layer 31 and the second capping layer 32 can be the same or different.

[0030] like Figure 1 As shown, the light-emitting device also includes a conductive layer 50. The conductive layer 50 is located on the surface of the first cover layer 31 near the second cover layer 32, and one electrode of each of the plurality of light-emitting structures 20 is electrically connected to the conductive layer 50 through a via.

[0031] The light-emitting structure 20 has two electrodes, such as a P-electrode and an N-electrode. In some examples, the P-electrodes of multiple light-emitting structures 20 can be connected to the conductive layer 50 through vias, thereby achieving a common P-electrode connection; in other examples, the N-electrodes of multiple light-emitting structures 20 can be connected to the conductive layer 50 through vias, thereby achieving a common N-electrode connection. Common polarity connection simplifies the structure of the light-emitting device.

[0032] The shape of the conductive layer 50 can be arbitrarily set, as long as it can connect to one pole of multiple light-emitting structures 20. Here, the shape of the conductive layer 50 refers to the shape of the orthographic projection of the conductive layer 50 on the surface of the first cover layer 31 near the second cover layer 32.

[0033] Optionally, a plurality of transition electrodes may be disposed on the surface of the first cover layer 31 near the second cover layer 32, and the plurality of transition electrodes are respectively connected to the other electrode of the plurality of light-emitting structures 20 through vias. The provision of transition electrodes facilitates the leading out of the other electrode of the plurality of light-emitting structures 20 to the surface of the light-emitting device.

[0034] like Figure 1 As shown, the light-emitting device also includes a plurality of welding electrodes 60. The plurality of welding electrodes 60 are located on the surface of the second cover layer 32 away from the first cover layer 31. Exemplarily, Figure 2 yes Figure 1 Top view, such as Figure 2 As shown, multiple welding electrodes 60 are distributed at the edge of the second cover layer 32.

[0035] The conductive layer 50 is electrically connected to one of the welding electrodes 60 through a via. One electrode of each of the multiple light-emitting structures 20 is electrically connected to the conductive layer 50 through a via, and the other electrode of each of the multiple light-emitting structures 20 is electrically connected to the other welding electrodes 60 among the multiple welding electrodes 60 through a via.

[0036] The welding electrode 60 is located on the surface of the second cover layer 32 away from the first cover layer 31, and is used for welding the light-emitting device. Since the conductive layer 50 is provided with common polarity connection, the total number of welding electrodes 60 only needs to be one more than the total number of light-emitting structures 20 to control the light emission of multiple light-emitting structures 20.

[0037] The distribution of multiple welding electrodes 60 at the edge of the second cover layer 32 can make the overall mass distribution of the light-emitting device more balanced, and make it easier to lift the light-emitting device with the ejector pin when transferring the light-emitting device.

[0038] When the welding electrode 60 is electrically connected to the light-emitting structure 20, it can be connected to the aforementioned transition electrode, making it easier for the welding electrode 60 to be electrically connected to the light-emitting structure 20.

[0039] like Figure 2 As shown, multiple welding electrodes 60 are located at the corners of the surface of the second cover layer 32 away from the first cover layer 31.

[0040] By placing the welding electrode 60 at the corner of the surface of the second cover layer 32 away from the substrate, a larger spacing can be created between the welding electrodes 60, reducing the risk of short circuits between different welding electrodes 60.

[0041] As an example, in this embodiment of the present disclosure, the surface of the second cover layer 32 away from the first cover layer 31 is rectangular, and the four welding electrodes 60 are distributed at the four corners of the rectangle.

[0042] Optionally, the support layer 40 is a metal layer. Metal has high structural strength and a certain rigidity, which can better support the light-emitting device and keep the relative positional relationship between the multiple light-emitting structures 20 unchanged.

[0043] For example, the support layer 40 can be a metal such as gold, silver, copper, or aluminum, or it can be an alloy. The support layer 40 can be a single-layer metal structure or a stacked structure formed by multiple metals.

[0044] Optionally, the thickness of the support layer 40 is 5μm to 20μm.

[0045] The thickness of the support layer 40 affects its rigidity. If the support layer 40 is too thin, its rigidity is low and its support for the light-emitting structure 20 is poor. If the support layer 40 is too thick, it will increase the overall thickness and weight of the light-emitting device and increase the manufacturing cost.

[0046] like Figure 1 As shown, the support layer 40 has multiple clearance holes 40a.

[0047] The purpose of providing clearance holes 40a on the support layer 40 is to form through holes in the clearance holes 40a so that the welding electrode 60 can be electrically connected to the conductive layer 50, etc., and to avoid short circuits caused by the support layer 40.

[0048] Figure 3 This is a schematic diagram of another substrate-free light-emitting device provided in an embodiment of this disclosure. Figure 3 As shown, the light-emitting device includes multiple light-emitting structures 20, a first cover layer 31, and a second cover layer 32. The first cover layer 31 covers the multiple light-emitting structures 20, and the second cover layer 32 is located on the first cover layer 31. The second cover layer 32 is a rigid insulating layer.

[0049] In this example, the second cover layer 32 is a rigid insulating layer with a certain rigidity, which can support the multiple light-emitting structures 20 and keep the relative positions between the multiple light-emitting structures 20 unchanged. This eliminates the need for a substrate to provide support, thus avoiding the influence of the substrate on the light emission angle and improving the display effect.

[0050] Optionally, the second capping layer 32 includes at least one of SiO2 or TiO2.

[0051] For example, the second capping layer 32 may include one or more SiO2 layers; for another example, the second capping layer 32 may include one or more TiO2 layers; for yet another example, the second capping layer 32 may include both SiO2 and TiO2 layers. Both the SiO2 and TiO2 layers may be single or multiple layers. When the second capping layer 32 includes multiple SiO2 and multiple TiO2 layers, the multiple SiO2 and multiple TiO2 layers may overlap, or the multiple SiO2 layers may be located on the surface of the multiple TiO2 layers away from the light-emitting structure 20, or the multiple TiO2 layers may be located on the surface of the multiple SiO2 layers away from the light-emitting structure 20.

[0052] Figure 3 The light-emitting device shown, except for the absence of the support layer 40 and the fact that the second cover layer 32 is a rigid insulating layer, can otherwise be compared with other light-emitting devices. Figure 1 and Figure 2 The light-emitting devices shown are the same.

[0053] Figure 4 This is a flowchart illustrating a method for fabricating a substrate-free light-emitting device according to an embodiment of this disclosure. This method is used to fabricate... Figure 1 or Figure 2 The image shows a substrate-free light-emitting device. (Example) Figure 4 As shown, the preparation method includes: In step S11, a plurality of light-emitting structures 20 are formed on the substrate bearing surface.

[0054] In step S12, a cover layer 30 and a support layer 40 are formed.

[0055] The cover layer 30 covers multiple light-emitting structures 20, and the support layer 40 is located inside the support layer 40.

[0056] In step S13, the substrate is removed.

[0057] By setting a cover layer 30, multiple light-emitting structures 20 are covered and connected into one unit. By setting a support layer 40 inside the cover layer 30, the relative positions between the multiple light-emitting structures 20 can remain unchanged. This eliminates the need for a substrate to provide support, allowing the substrate to be removed during manufacturing. This also avoids the influence of the substrate on the light emission angle, which is beneficial to improving the display effect.

[0058] Figure 5 This is a flowchart illustrating a method for fabricating a substrate-free light-emitting device according to an embodiment of this disclosure. This method is used to fabricate... Figure 1 or Figure 2 The image shows a substrate-free light-emitting device. (Example) Figure 5 As shown, the preparation method includes: In step S21, a substrate is provided.

[0059] For example, the substrate can be a transparent substrate, such as a sapphire substrate, or a Si substrate or a GaAs substrate.

[0060] In step S22, a carrier layer 11 is formed on the substrate.

[0061] For example, the carrier layer 11 can be formed on the carrier surface of the substrate by spin coating. The carrier layer 11 can be formed of an organic material, and the thickness of the carrier layer 11 can be 3 μm to 30 μm.

[0062] In step S23, a plurality of light-emitting structures 20 are formed on the substrate.

[0063] The light-emitting structure 20 can be fabricated via epitaxial growth. After fabrication, it is then transferred onto a substrate. In some examples, the light-emitting structure 20 can also be grown directly on the substrate.

[0064] The multiple light-emitting structures 20 may include light-emitting structures 20 with different light-emitting colors. For example, there may be three light-emitting structures 20 arranged in a straight line. These three light-emitting structures 20 are a red light-emitting structure emitting red light, a red light-emitting structure emitting green light, and a red light-emitting structure emitting blue light, respectively.

[0065] The carrier layer 11 can then be etched. For light-emitting devices with a substrate, dicing and splitting are required in the later stages of fabrication to form individual light-emitting devices. In this example, the substrate will be removed later. To facilitate the formation of individual light-emitting devices, the carrier layer 11 can be etched first, so that after the substrate is removed, it will be split into individual light-emitting devices.

[0066] In step S24, a first covering layer 31 is formed.

[0067] like Figure 1 As shown, the first capping layer 31 covers multiple light-emitting structures 20. The first capping layer 31 can be formed using organic materials. For example, the first capping layer 31 can be formed by spin coating. The thickness of the first capping layer 31 is greater than the thickness of the light-emitting structures 20, so that the light-emitting structures 20 are completely covered.

[0068] For example, the thickness of the first cover layer 31 can be 0.5 μm to 10 μm.

[0069] In step S25, a conductive layer 50 is formed on the surface of the first cover layer 31 away from the substrate.

[0070] like Figure 1As shown, the conductive layer 50 can be electrically connected to multiple light-emitting structures 20 through vias. Each light-emitting structure 20 has two electrodes, such as a P-electrode and an N-electrode. The conductive layer 50 can be connected to either the P-electrode or the N-electrode of the light-emitting structure 20 through vias, thereby achieving a common polarity connection. This common polarity connection simplifies the structure of the light-emitting device.

[0071] For example, the conductive layer 50 can be formed by a vapor deposition process and a patterning process.

[0072] In step S26, a portion of the second cover layer 32 is formed on the surface of the first cover layer 31 away from the substrate.

[0073] The second capping layer 32 can be formed using an organic material. For example, the second capping layer 32 can be formed by spin coating. The thickness of the second capping layer 32 is greater than the thickness of the conductive layer 50, so that the conductive layer 50 is completely covered.

[0074] For example, the thickness of the second cover layer 32 can be 0.5 μm to 10 μm.

[0075] In this method, the second cover layer 32 is fabricated in two steps. The portion of the second cover layer 32 referred to here refers to the portion of the thickness of the second cover layer 32 formed. For example, if the total thickness of the second cover layer 32 is 10 μm, then in step S26, a 5 μm thick portion can be formed first, and the remaining 5 μm thick portion can be formed in subsequent steps, thereby obtaining a second cover layer 32 with a total thickness of 10 μm.

[0076] In step S27, a support layer 40 is formed.

[0077] For example, the support layer 40 is a metal layer, which can be formed by vapor deposition, patterning, electroplating, chemical plating, etc. For example, the support layer 40 can be a metal such as gold, silver, copper, or aluminum, or it can be an alloy. The support layer 40 can be a single-layer metal structure or a multi-layer metal stacked structure.

[0078] For example, the thickness of the support layer 40 is 5μm to 20μm.

[0079] In step S28, the remaining portion of the second covering layer 32 is formed.

[0080] In step S29, a welding electrode 60 is formed on the surface of the second cover layer 32 away from the substrate.

[0081] For example, the welding electrode 60 is disposed at a corner of the surface of the second cover layer 32 away from the substrate.

[0082] One of the multiple welding electrodes 60 is electrically connected to the conductive layer 50 through a via. One electrode of each of the multiple light-emitting structures 20 is electrically connected to the conductive layer 50 through a via, and the other electrode of each of the multiple light-emitting structures 20 is electrically connected to the other welding electrodes 60 of the multiple welding electrodes 60 through a via.

[0083] In step S30, the substrate is removed.

[0084] For example, the substrate can be removed by chemical etching. GaAs substrates, for instance, can be etched using chemicals. Alternatively, the substrate can be removed by stripping. Substrates that are difficult to etch, such as sapphire and glass substrates, can be removed by stripping. This process then yields multiple light-emitting devices.

[0085] Figure 6 This is a flowchart illustrating a method for fabricating a substrate-free light-emitting device according to an embodiment of this disclosure. This method is used to fabricate... Figure 3 The image shows a substrate-free light-emitting device. (Example) Figure 6 As shown, the preparation method includes: In step S31, a plurality of light-emitting structures 20 are formed on the substrate bearing surface.

[0086] In step S32, a first covering layer 31 is formed.

[0087] The first covering layer 31 covers multiple light-emitting structures 20.

[0088] In step S33, a second covering layer 32 is formed.

[0089] The second cover layer 32 is located on the first cover layer 31, and the second cover layer 32 is a rigid insulating layer.

[0090] In step S34, the substrate is removed.

[0091] Figure 6 The fabrication method of the light-emitting device shown is similar to Figure 5 The fabrication method of the light-emitting device shown differs only in the fabrication of the second capping layer 32; the fabrication of other structures can be referred to the same method. Figure 5 The preparation method shown.

[0092] In this example, the second cover layer 32 is a rigid insulating layer with a certain rigidity, which can support multiple light-emitting structures 20 and keep the relative positions between the multiple light-emitting structures 20 unchanged. This eliminates the need for a substrate to provide support, allowing the substrate to be removed during manufacturing. This avoids the influence of the substrate on the light emission angle and helps improve the display effect.

[0093] Unless otherwise defined, the technical or scientific terms used herein shall have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms “first,” “second,” “third,” and similar terms used in this patent application specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms “an” or “a” and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms “comprising” or “including” and similar terms mean that the element or object preceding “comprising” or “including” encompasses the element or object listed following “comprising” or “including” and its equivalents, and do not exclude other elements or objects. The terms “connected” or “linked” and similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. The terms “upper,” “lower,” “left,” “right,” etc., are used only to indicate relative positional relationships, and these relative positional relationships may change accordingly when the absolute position of the described object changes.

[0094] The above description is merely an optional embodiment of this disclosure and is not intended to limit this disclosure. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the protection scope of this disclosure.

Claims

1. A substrate-free light-emitting device, characterized in that, The device includes a cover layer (30), a support layer (40), multiple light-emitting structures (20), a conductive layer (50), and multiple welding electrodes (60). The cover layer (30) includes a first cover layer (31) and a second cover layer (32). The first cover layer (31) covers the multiple light-emitting structures (20), and the second cover layer (32) is located on the first cover layer (31). The support layer (40) is located inside the second cover layer (32). The support layer (40) has a clearance hole (40a), and a first through hole is formed in the clearance hole (40a) to electrically connect the welding electrodes (60) with the conductive layer (50). The conductive layer (50) is located on the surface of the first cover layer (31) near the second cover layer (32), and one pole of each of the plurality of light-emitting structures (20) is electrically connected to the conductive layer (50) through a second via. The plurality of welding electrodes (60) are located on the surface of the second cover layer (32) away from the first cover layer (31).

2. The light-emitting device according to claim 1, characterized in that, It also includes a carrier layer (11), on which the plurality of light-emitting structures (20) are located, and the cover layer (30) covers the surface of the carrier layer (11).

3. The light-emitting device according to claim 1, characterized in that, The support layer (40) is a metal layer.

4. The light-emitting device according to claim 3, characterized in that, The thickness of the support layer (40) is 5μm~20μm.

5. A method for fabricating a substrate-free light-emitting device, characterized in that, include: Multiple light-emitting structures are formed on the substrate bearing surface (20). A cover layer (30), a conductive layer (50), a support layer (40), and a plurality of welding electrodes (60) are formed. The cover layer (30) includes a first cover layer (31) and a second cover layer (32). The first cover layer (31) covers the plurality of light-emitting structures (20). The second cover layer (32) is located on the first cover layer (31). The support layer (40) is located inside the second cover layer (32). The support layer (40) has a clearance hole (40a). A first through hole is formed in the clearance hole (40a) to make the welding electrodes (60) electrically connected to the conductive layer (50). The conductive layer (50) is located on the surface of the first cover layer (31) near the second cover layer (32), and one pole of each of the plurality of light-emitting structures (20) is electrically connected to the conductive layer (50) through a second via. The plurality of welding electrodes (60) are located on the surface of the second cover layer (32) away from the first cover layer (31); Remove the substrate.

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