An all-inorganic packaging structure and packaging method for ultraviolet devices

Abstract

This invention relates to the technical field of LED packaging, and discloses an all-inorganic packaging structure and method for ultraviolet (UV) devices. The all-inorganic packaging structure includes a substrate, a dam support, a UV chip, and a light window cover. The top of the dam support has a limiting groove for placing the light window cover. The light window cover is placed in the limiting groove of the dam support, and the light window cover is hermetically welded to the dam support through an alloy layer. The alloy layer is formed by eutectic bonding of a metal layer and a solder layer. The interaction between the metal layer and the solder layer is used to achieve the packaging of the UV device, ensuring that there are no impurities in the packaging cavity, effectively protecting the luminescent performance of the UV chip. Moreover, the UV device has good hermetical tightness, good weather resistance, high reliability, and can reduce costs.

Description

Technical Field

[0001] This invention relates to the technical field of LED packaging, and in particular to an all-inorganic packaging structure and packaging method for ultraviolet devices. Background Technology

[0002] Ultraviolet (UV) devices, especially deep UV devices, have high photon energies, so conventional silicone sealant cannot be used as an encapsulating agent. Therefore, sapphire and quartz glass are commonly used as optical transmission materials in UV device encapsulation. However, quartz and sapphire are high-temperature manufactured materials, so they must be prepared beforehand and then used in the encapsulation process, unlike silicone sealant which can be cured during encapsulation to ensure complete adhesion of the optical transmission material to the chip surface.

[0003] Currently, the encapsulation methods for ultraviolet devices using quartz or sapphire windows as optical transmission materials mainly include the following two types: one is semi-inorganic encapsulation, which involves bonding the quartz or sapphire window to the enclosure using resin adhesive; the other is fully inorganic encapsulation, which involves combining the quartz or sapphire window with a metal frame, and then welding the metal frame to the enclosure using methods such as laser welding. However, both methods have certain drawbacks. In the semi-inorganic encapsulation method, the materials used are resin-based organic materials, and the chemical bonds such as carboxyl groups (-COOH) contained in these materials are prone to photolysis under deep ultraviolet light irradiation. In the application of ultraviolet devices, long-term exposure to ultraviolet light may cause discoloration and aging, thus affecting reliability. On the other hand, the welding method in fully inorganic encapsulation is prone to high costs. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide an all-inorganic packaging structure and packaging method for ultraviolet devices, which have good airtightness, high reliability and reduced cost.

[0005] To address the aforementioned technical problems, the first aspect of this invention provides an all-inorganic packaging structure for ultraviolet devices, comprising:

[0006] substrate;

[0007] A cavity-filled dam support is provided around the substrate;

[0008] At least one ultraviolet chip is disposed on the substrate, and the ultraviolet chip is located within the cavity of the dam support;

[0009] A light window cover plate adapted to the dam support frame;

[0010] The top of the dam support has a limiting groove for placing the light window cover plate. The light window cover plate is placed in the limiting groove of the dam support, and the light window cover plate and the dam support are airtightly welded by an alloy layer. The alloy layer is formed by eutectic bonding of a metal layer and a solder sheet layer.

[0011] The metal layer includes a first metal layer and a second metal layer. The first metal layer is disposed on the side of the light window cover plate near the limiting groove, and the second metal layer is disposed on the side of the limiting groove near the light window cover plate. The solder sheet layer is disposed between the first metal layer and the second metal layer.

[0012] As an improvement to the above solution, at least one allowance portion for placing the light window cover is formed on the limiting groove; a curved structure is formed on the edge of the limiting groove.

[0013] As an improvement to the above solution, the bending structure is a convex structure or a concave structure;

[0014] The maximum bending width of the bending structure is d1, and the distance between the outer edge of the limiting groove and the outer edge of the dam support is d2, where d1 < 0.5d2.

[0015] The maximum bending length of the bending structure is d3, and the outer width of the limiting groove is W1, where d3 < 0.5W1 or 0.7W1 < d3 < W1.

[0016] As an improvement to the above scheme, the thickness ratio of the first metal layer to the solder layer is 1:(2~400).

[0017] As an improvement to the above scheme, the thickness ratio of the first metal layer and the second metal layer is 1:(1~10);

[0018] The thickness of the first metal layer is 0.2 μm to 10 μm;

[0019] The thickness of the solder sheet layer is 20μm to 80μm.

[0020] As an improvement to the above scheme, the first metal layer includes at least an Au layer.

[0021] As an improvement to the above scheme, the first metal layer is one of Au layer, Ti layer / Au layer, or Ti layer / Ni layer / Au layer;

[0022] The solder pad layer is one of Au / Si solder pad layer and Sn / Sb solder pad layer, the eutectic temperature of the solder pad layer is 240℃~340℃, and the solder pad layer is fixed on the groove by flux.

[0023] As an improvement to the above solution, the outer width of the limiting groove is W1, the width of the light window cover is W2, the outer width of the first metal layer is W3, the inner width of the first metal layer is W4, the inner width of the solder sheet layer is W5, and the outer width of the solder sheet layer is W6, satisfying W1-W3>W1-W6≥W1-W2.

[0024] The width (W3-W4) / 2 of the first metal layer is 100μm to 300μm;

[0025] The distance (W2-W3) / 2 between the outer edge of the first metal layer and the edge of the light window cover plate is 10μm to 50μm;

[0026] The distance (W1-W6) / 2 between the outer edge of the solder sheet layer and the outer edge of the limiting groove is 30μm to 50μm;

[0027] The width (W6-W5) / 2 of the solder pad layer is 150μm to 300μm.

[0028] A second aspect of the present invention also provides a packaging method for the all-inorganic packaging structure of the ultraviolet device, comprising:

[0029] An ultraviolet chip is placed on the front side of the substrate;

[0030] A dam support with a cavity and a limiting groove is formed on the front side of the substrate, so that the ultraviolet chip is located in the cavity of the dam support;

[0031] A first metal layer is formed on the light window cover plate, and a second metal layer is formed on the limiting groove;

[0032] A solder sheet is placed on the first metal layer to form a solder sheet layer;

[0033] A light window cover is placed on the solder sheet layer, so that the solder sheet layer and the second metal layer are positioned opposite each other. An alloy layer is formed by eutectic welding. The light window cover and the dam support are welded together to obtain the all-inorganic packaging structure of the ultraviolet device.

[0034] As an improvement to the above scheme, the eutectic welding is vacuum eutectic welding, which includes: maintaining a high temperature of 240℃~340℃ for 10s~30s in a vacuum environment.

[0035] Implementing this invention has the following beneficial effects:

[0036] In this application, the all-inorganic packaging structure of the ultraviolet device includes a substrate, a dam support, an ultraviolet chip, and a light window cover. The top of the dam support has a limiting groove for placing the light window cover. The light window cover is placed in the limiting groove of the dam support, and the light window cover and the dam support are hermetically welded through an alloy layer. The alloy layer is formed by eutectic bonding of a metal layer and a solder layer. The interaction between the metal layer and the solder layer is used to encapsulate the ultraviolet device, ensuring that there are no impurities in the packaging cavity, which effectively protects the light-emitting performance of the ultraviolet chip. Moreover, the ultraviolet device has good hermetical tightness, good weather resistance, high reliability, and can reduce costs. Attached Figure Description

[0037] Figure 1 : A schematic diagram of the all-inorganic packaging structure of the ultraviolet device provided in Embodiment 1 of this invention;

[0038] Figure 2 : Figure 1 A cross-sectional schematic diagram;

[0039] Figure 3 : Figure 2 A magnified view of a section at point A in the middle;

[0040] Figure 4 : A schematic diagram of the structure of Embodiment 1 of the present invention without the light window cover plate being sealed;

[0041] Figure 5 : A schematic diagram of the structure of the light window cover plate in this invention;

[0042] Figure 6 : A schematic diagram of the structure of the solder sheet layer in this invention;

[0043] Figure 7 : A schematic diagram of the structure of Embodiment 2 of the present invention without the light window cover being sealed;

[0044] Figure 8 : A schematic diagram of the structure of Embodiment 3 of the present invention without the light window cover being sealed;

[0045] Figure 9 : A schematic diagram of the structure of the solder sheet layer in Embodiment 3 of this invention;

[0046] Figure 10 : A schematic diagram of the structure of Embodiment 4 of the present invention without the light window cover being sealed;

[0047] Figure 11 : A schematic diagram of the structure of the solder sheet layer in Embodiment 4 of this invention;

[0048] Figure 12 : A schematic diagram of the structure after flux is placed in the limiting groove of the dam support in this invention;

[0049] Figure 13 CT scan image of the all-inorganic packaging structure of the ultraviolet device provided in Embodiment 1 of this invention;

[0050] Figure 14 : CT scan of the all-inorganic packaging structure of the ultraviolet device provided in the control group of this invention.

[0051] Figure label:

[0052] 1-Substrate; 2-Dam support; 3-UV chip; 4-Light window cover; 5-Limiting groove; 6-First metal layer; 7-Solder layer; 8-Solder pad; 9-Maintenance portion; 10-Bending structure; 11-Fluoride. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of the present invention clearer, specific embodiments will be described in further detail below.

[0054] In the description of this application, it is necessary to understand that the orientation or positional relationship indicated by terms such as "upper", "lower", "top", "bottom", "inner", and "outer" are based on the orientation or positional relationship shown in the accompanying drawings. They are intended only to facilitate the description of the present invention and to simplify the description, and are not intended to indicate or imply that the components referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0055] The all-inorganic packaging of ultraviolet devices mainly involves welding the light window cover plate 4 and the dam support 2 together to seal the ultraviolet chip. Conventional light window cover plate 4 is a metallized light window cover plate, and the dam support 2 has a metal layer, which can be directly welded and sealed with solder paste. However, through multiple experiments, it was found that some organic components contained in the solder paste will be sealed inside the cavity of the ultraviolet device after sealing, causing a significant reduction in the light emission performance of the ultraviolet device. Therefore, the welding method of using liquid solder paste cannot be widely used.

[0056] To address the aforementioned problems, the first aspect of this invention provides an all-inorganic packaging structure for ultraviolet devices. Please refer to [link to relevant documentation]. Figure 1 The device includes: a substrate 1; a dam support 2 with a cavity surrounding the substrate 1; at least one ultraviolet chip 3 disposed on the substrate 1, the ultraviolet chip 3 being located within the cavity of the dam support 2; and a light window cover plate 4 adapted to the dam support 2.

[0057] Please see Figure 2The substrate 1 has two sets of pads 8, each set located on the upper and lower sides of the substrate 1. These pads are electrically connected via conductive vias, and a gap exists between them. The ultraviolet chip 3 is placed on both sets of pads 8. Optionally, the ultraviolet chip 3 is fixed to the pads 8 using soldering material. The substrate 1 also has at least one pair of electrodes, each pair including a first electrode and a second electrode. The first and second electrodes are respectively disposed on the two sets of pads 8. The ultraviolet chip 3 is electrically connected to the electrodes to achieve light emission. In some embodiments, the first and second electrodes can be fixed to the corresponding pads 8 using soldering material, including but not limited to gold-tin alloy. Bonding wires are used between the ultraviolet chip 3 and the electrodes to achieve electrical connection. These bonding wires can be one or a mixture of gold wire, copper wire, silver wire, aluminum wire, gold-plated silver wire, and alloy wire.

[0058] Optionally, at least one protective element is further provided on the substrate 1. The protective element is connected in parallel with the ultraviolet chip 3 to provide protection for the ultraviolet chip 3, reduce the risk of damage to the ultraviolet chip 3, and maintain the stability and reliability of the ultraviolet chip 3. Examples of such elements include anti-static protection elements, overvoltage protection elements, and capacitor protection elements.

[0059] Understandably, the substrate 1 can be a ceramic substrate, and the substrate 1 can be square, rectangular, or circular. The dam support 2 can be welded around the substrate 1 to form a cavity structure enclosing the substrate 1, or the dam support 2 can be integrally formed with the substrate 1. The light window cover 4 is made of an optically transparent material with high ultraviolet light transmittance. The light window cover 4 can be quartz, sapphire, or other materials. This invention is not limited to these, and any corresponding material implementation is within the protection scope of this invention.

[0060] Please see Figure 3The top end of the dam support 2 has a limiting groove 5 for placing the light window cover plate 4. The light window cover plate 4 is placed in the limiting groove 5 of the dam support 2, and the light window cover plate 4 and the dam support 2 are hermetically welded through an alloy layer (not shown in the figure). The alloy layer is formed by eutectic bonding of a metal layer and a solder layer 7. The metal layer includes a first metal layer 6 and a second metal layer (not shown in the figure). The first metal layer 6 is disposed on the side of the light window cover plate 4 near the limiting groove 5, and the second metal layer is disposed on the side of the limiting groove 5 near the light window cover plate 4. The solder layer 7 is disposed between the first metal layer 6 and the second metal layer. In this application, the interaction between the metal layer and the solid solder layer 7 realizes the encapsulation of the ultraviolet device, avoids the use of solder paste, and ensures that there are no impurities in the encapsulation cavity, thereby effectively protecting the light-emitting performance of the ultraviolet chip. Moreover, the ultraviolet device has good hermetical tightness, good weather resistance, high reliability, and can reduce costs.

[0061] Preferably, the thickness ratio of the first metal layer 6 to the solder pad layer 7 is 1:(2~400), forming an alloy layer with low void ratio between the first metal layer 6 and the solder pad layer 7, achieving connection between the first metal layer 6 and the solder pad layer 7, and strengthening the bonding force between the first metal layer 6 and the light window cover plate 4, thereby improving the airtightness of the ultraviolet device. In some embodiments, the thickness of the first metal layer 6 is 0.2μm to 10μm, and exemplary values ​​can be 0.2μm, 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, etc., but are not limited thereto. If the thickness of the first metal layer 6 is less than 0.2μm, it is easy for the material of the first metal layer 6 to peel off from the light window cover plate 4 after encapsulation. If the thickness of the first metal layer 6 is greater than 10μm, it is easy for the first metal layer 6 to be uneven after encapsulation, thereby reducing the airtightness. In some embodiments, the thickness of the solder pad layer 7 is 20μm to 80μm. If the thickness of the solder pad layer 7 is less than 20μm, it will easily cause difficulties in picking up and self-supporting during the process. Moreover, insufficient welding material will lead to voids in some welding areas, making it impossible to form a welding layer on the entire welding surface, resulting in a decrease in the hermeticity of the package. However, if the thickness of the solder pad layer 7 is greater than 80μm, it will increase the cost, and some solder pad materials will not be able to form an alloy with the upper and lower welding surfaces, which will also cause a decrease in reliability.

[0062] Please see Figure 4 and Figure 5The outer width of the limiting groove 5 is W1, and the width of the light window cover plate 4 is W2. To facilitate the installation of the light window cover plate 4, W1 is set to be greater than W2, so that there is a certain gap between the light window cover plate 4 and the limiting groove 5. The gap distance is 0.5(W1-W2); more preferably, W1-W2 = 50μm to 100μm, exemplarily 50μm, 55μm, 60μm, 65μm, 70μm, etc., but not limited to these. If the gap between the light window cover plate 4 and the limiting groove 5 is too large, the overall light window cover plate 4 is prone to being offset to one side or one corner of the package body after encapsulation, resulting in insufficient airtightness of the package body. If the gap between the light window cover plate 4 and the limiting groove 5 is too small, the light window cover plate 4 may be unable to be placed in the limiting groove 5 due to the influence of the equipment's positional accuracy and angular accuracy during the process of placement. Optionally, a metal layer (not shown in the figure) can be provided between the gap between the light window cover plate 4 and the limiting groove 5 to increase the sealing between the side wall of the light window cover plate 4 and the dam support 2. The metal layer here includes, but is not limited to, the Au layer.

[0063] Please see Figure 5 The first metal layer 6 is disposed on the side of the light window cover plate 4 near the limiting groove. It can be formed by depositing the first metal layer 6 on the light window cover plate 4 to create a metallized light window, and then using it to form an alloy layer through eutectic bonding with the solder pad layer 7 to achieve fully inorganic encapsulation of the ultraviolet device. The shape of the first metal layer 6 is adapted to the limiting groove 5 and can be formed on the light window cover plate 4 through a coating process. The first metal layer 6 can be a single-layer structure or a multi-layer structure, preferably including at least an Au layer, which has better chemical stability and corrosion resistance, and can meet the performance requirements of the ultraviolet device in various applicable environments. More preferably, the first metal layer 6 is a transition metal layer and an Au layer. The transition first metal layer 6 can prevent the first metal layer 6 from peeling off from the light window cover plate 4 due to excessive difference in the coefficient of thermal expansion between the first metal layer 6 and the light window cover plate 4. The transition metal layer includes, but is not limited to, Ti layers, Ni layers, Cr layers, and Zn layers. For example, the first metal layer 6 is a Ti layer / Au layer or a Ti layer / Ni layer / Au layer.

[0064] Furthermore, the first metal layer 6 has an inner edge close to the light-emitting center and an outer edge far from the light-emitting center. The distance between the two inner edges is the inner width of the first metal layer 6, and the distance between the two outer edges is the outer width of the first metal layer 6. The outer width of the first metal layer 6 is W3, and the inner width of the first metal layer 6 is W4. The width of the first metal layer 6 is 100μm to 300μm, i.e., (W3-W4) / 2=100μm to 300μm, which facilitates the formation of a sufficient welding surface with the solder pad layer 7 and does not affect the light efficiency during ultraviolet light. The width of the first metal layer 6 can be, for example, 100μm, 150μm, 200μm, 250μm, 300μm, etc., but is not limited to these. If the width of the first metal layer 6 is less than 100μm, the welding reliability and airtightness will be reduced due to the first metal layer 6 being too narrow. If the width of the first metal layer 6 is greater than 300μm, it will cause the first metal layer 6 to excessively block the central light-transmitting area, thereby reducing the light efficiency of the packaged device. In some specific and preferred embodiments, the distance between the outer edge of the first metal layer 6 and the edge of the light window cover plate 4 is 10μm to 50μm, that is, (W2-W3) = 20μm to 100μm. This not only prevents the first metal layer 6 from being damaged and peeled off when cutting small pieces of metallized light window during the metallization process, but also avoids the metal area being too narrow or too close to the center, reducing the light-transmitting area and causing a decrease in the overall light efficiency of the packaged device. The distance between the outer edge of the first metal layer 6 and the edge of the light window cover plate 4 is exemplarily 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, etc., but is not limited thereto.

[0065] The second metal layer is disposed on the side of the limiting groove 5 near the light window cover plate 4. It can be disposed on the contact surface between the limiting groove 5 and the light window cover plate 4, forming a dam support with a metal layer. Preferably, the second metal layer can be a single-layer structure or a multi-layer structure, and preferably includes at least an Au layer. More preferably, the second metal layer is a transition metal layer and an Au layer. The transition metal layer includes, but is not limited to, a Ti layer, a Ni layer, a Cr layer, and a Zn layer. Exemplarily, the second metal layer is a Ti / Au layer or a Ti / Ni / Au layer. The composition of the first metal layer 6 and the second metal layer can be the same or different. The thickness ratio of the first metal layer to the second metal layer is 1:(1-10). A high-performance alloy layer can be formed between the first metal layer 6 and the second metal layer using a solder layer 7. In some embodiments, the thickness of the second metal layer is 1 μm to 100 μm.

[0066] Understandably, if the materials used in the dam support 2 and / or the light window cover plate 4 contain Au-Sn alloy, the use of the solder sheet layer 7 can be avoided, and the light window cover plate 4 and the dam support 2 can be directly welded together to achieve the sealing of the ultraviolet chip. However, no suitable materials have been found at present, and the application of such materials would result in high costs.

[0067] Please see Figure 6 The solder pad layer 7 is an annular layer structure adapted to the first metal layer 6, having an inner edge near the light-emitting center and an outer edge away from the light-emitting center. The solder pad layer 7 is fixed to the groove by flux 11. The flux 11 can activate the welding surface, improving the welding quality of the metal layer and the solder pad layer 7. The flux 11 can be spot-applied on the limiting groove 5 or uniformly coated on the groove. To reduce production costs, the flux 11 can be spot-applied on the limiting groove 5, and the number of spot applications can be 3 to 6. The eutectic temperature of the solder pad layer 7 is 240℃ to 340℃. If the eutectic temperature of the solder pad layer 7 is higher than 340℃, it is easy to cause secondary melting of the internal chip eutectic layer, resulting in a decrease in reliability. If the eutectic temperature of the solder pad layer 7 is lower than 240℃, it will affect the subsequent application of the package and may result in insufficient welding reliability during operation. For example, the solder layer 7 is one of Au / Si solder layer and Sn / Sb solder layer. Of course, the solder layer 7 can also be a layer structure formed of other materials. The present invention is not limited thereto, and any corresponding material implementation is within the protection scope of the present invention.

[0068] Furthermore, the width of the solder pad layer 7 is slightly larger than the width of the first metal layer 6 to ensure the formation of the metal solder layer. Specifically, the distance between the two inner edges of the solder pad layer 7 is the inner width of the solder pad layer 7, and the distance between the two outer edges is the outer width of the solder pad layer 7. The inner width of the solder pad layer 7 is W5, and the outer width is W6. The width of the solder pad layer 7 is 150μm to 300μm, i.e., (W6-W5) / 2 = 150μm to 300μm. If the width of the solder pad layer 7 is less than 150μm, it will cause a decrease in soldering reliability and airtightness. Controlling the width of the solder pad layer 7 to be less than 300μm can avoid the solder pad layer 7 excessively blocking the central light-transmitting area and avoid reducing the light efficiency of the packaged device.

[0069] Furthermore, the distance between the outer edge of the welding sheet layer 7 and the outer edge of the limiting groove 5 is 30μm to 50μm, i.e. W1-W6=60μm to 100μm. This not only facilitates the smooth placement of the light window cover plate 4, but also allows for precise control of the sealing position of the light window cover plate 4, enabling direct welding between the light window cover plate 4 and the dam support 2.

[0070] In some preferred and specific embodiments, satisfying W1-W3>W1-W6≥W1-W2 is beneficial to the realization of eutectic welding between the first metal layer 6 and the solder layer 7, thereby improving the hermeticity of the ultraviolet device packaging, and the luminous efficiency can also be maintained within a certain range, extending the reliability and service life of the ultraviolet device.

[0071] According to another embodiment of the present invention, at least one allowance 9 for placing the light window cover plate 4 is formed on the limiting groove 5, such as... Figure 7 As shown, to prevent the light window cover plate 4 and the solder sheet layer 7 from misaligning during the processing and failing to be properly placed into the limiting groove 5, the allowance portion 9 improves the process yield. Simultaneously, the allowance portion 9 can also store more flux during the flux 11 application process, preventing insufficient flux dosage during eutectic welding, which could lead to poor eutectic quality and affect airtightness. It is understood that the allowance portion 9 can be a rounded groove, or other shapes; this invention is not limited to these, and any corresponding structural implementation is within the scope of protection of this invention.

[0072] Furthermore, the shortest distance from the edge of the allowance portion to the outer edge of the dam support is d4, and the distance between the outer edge of the limiting groove and the outer edge of the dam support is d2, where d4 < 0.5d2, so that the limiting groove 5 maintains a certain thickness, thereby ensuring the reliability of the dam support 2.

[0073] According to another embodiment of the present invention, a curved structure 10 is formed on the edge of the limiting groove 5, preferably between two flux points 11. This can increase the thickness of the solder pad layer 7, improve the welding effect between the first metal layer 6 and the solder pad layer 7, prevent the middle part from breaking during the eutectic process between the first metal layer 6 and the solder pad layer 7, thus avoiding poor eutectic welding effect in the middle region and preventing airtightness problems. Furthermore, it reduces the packaging cost of the ultraviolet device. The curved structure 10 is a raised or recessed structure, which not only maintains the supporting function of the limiting groove 5 on the light window cover plate 4, but also maximizes the thickness of the solder pad layer 7. To avoid reducing the luminous efficiency of the ultraviolet device due to the curved structure 10, the distance between the outer edge of the limiting groove 5 and the outer edge of the dam support 2 is d2, and d2 is controlled to be less than 0.5W4.

[0074] In some embodiments, a raised structure is formed on the outer edge of the limiting groove 5, and the raised structure is located between the two flux points 11, such as... Figure 8 and Figure 9As shown, the maximum bending width of the bending structure 10 is d1, where d1 < 0.5d2. If the maximum bending width of the bending structure 10 is too large, it will reduce the reliability of the dam support 2. The maximum bending length of the bending structure 10 is d3, where 0.7W1 < d3 < W1. In some other embodiments, a recessed structure is formed on the inner edge of the limiting groove 5, and this recessed structure is located between two fluxes 11, such as... Figure 10 and Figure 11 As shown, the maximum bending width of the bending structure 10 is d1, the distance between the outer edge of the limiting groove 5 and the outer edge of the dam support 2 is d2, d1 < 0.5d2, the maximum bending length of the bending structure 10 is d3, d3 < 0.5W1. If the maximum bending length d3 of the bending structure 10 is too large, it will affect the light emission path of the ultraviolet chip 3, thereby reducing the light efficiency of the ultraviolet device.

[0075] Accordingly, the present invention also provides a packaging method for the all-inorganic packaging structure of the ultraviolet device, comprising:

[0076] (1) An ultraviolet chip 3 is disposed on the front side of the substrate 1;

[0077] In this step, the substrate 1 is provided with pads 8, and the ultraviolet chip 3 is placed on the pads 8. Optionally, the ultraviolet chip 3 is fixed to the pads 8 by soldering material. The substrate 1 is also provided with at least one pair of electrodes, each pair of electrodes including a first electrode and a second electrode. The first electrode and the second electrode are respectively disposed on the pads 8, and the ultraviolet chip 3 is electrically connected to the electrodes to realize the light emission of the ultraviolet chip 3.

[0078] (2) A dam support 2 with a cavity and a limiting groove 5 is formed on the front side of the substrate 1, so that the ultraviolet chip 3 is located in the cavity of the dam support 2.

[0079] In this step, the limiting groove 5 is used to place the light window cover plate 4, forming a structure as follows: Figure 4 As shown. If the limiting groove 5 has an allowance portion 9 and / or a bent structure 10, it can also be formed in this step.

[0080] (3) A first metal layer is formed on the light window cover plate, and a second metal layer is formed on the limiting groove;

[0081] In this step, a metallized light window is formed by depositing a first metal layer 6 on the light window cover plate 4. This metallized light window then contacts the solder pad layer 7 to achieve fully inorganic encapsulation of the ultraviolet device. During the formation of the metallized light window, the width W2 of the light window cover plate 4 is controlled to be less than the width of the limiting groove 5, ensuring a certain gap between the light window cover plate 4 and the limiting groove 5. The width of the first metal layer 6 is (W3-W4) / 2 = 100μm to 300μm, and the distance between the outer edge of the first metal layer 6 and the edge of the light window cover plate 4 is (W2-W3) / 2 10μm to 50μm. The first metal layer 6 can be formed on the light window cover plate 4 using a coating process.

[0082] The second metal layer is disposed on the side of the limiting groove 5 near the light window cover plate 4. It can be disposed on the contact surface between the limiting groove 5 and the light window cover plate 4, so that the second metal layer covers the contact surface, forming a dam support with a metal layer.

[0083] (4) Placing solder pads on the first metal layer to form a solder pad layer;

[0084] Specifically, flux 11 is applied to the first metal layer, and then solder pads are placed to form a solder pad layer 7.

[0085] In this step, the flux 11 can be applied in dots on the limiting groove 5 or uniformly coated on the groove. To reduce production costs while maintaining the same welding effect, it is preferable to apply the flux 11 in dots on the limiting groove 5. Figure 12 As shown; the number of flux 11 spots can be 3 to 6. Subsequently, the solder sheet layer 7 is placed in the limiting groove 5, so that the flux 11 is in full contact with the solder sheet layer 7, and the solder sheet layer 7 is fixed on the dam support 2. During the placement process, the distance between the outer edge of the solder sheet layer 7 and the outer edge of the limiting groove 5 is reasonably controlled to be 30μm to 50μm, that is, W1-W6=60μm to 100μm.

[0086] (5) Place the light window cover plate 4 on the solder sheet layer 7, so that the solder sheet layer 7 and the second metal layer are arranged opposite to each other, and form an alloy layer by eutectic welding. Then weld the light window cover plate 4 and the dam support 2 together to obtain the all-inorganic packaging structure of the ultraviolet device.

[0087] Preferably, the eutectic welding is vacuum eutectic welding. Through the vacuum eutectic welding process, an alloy layer is formed between the metal layer and the solder layer 7, which reduces the welding temperature and results in a low void ratio in the alloy layer, thus improving the airtightness of the ultraviolet device.

[0088] Furthermore, the vacuum eutectic welding includes maintaining a high temperature of 240℃ to 340℃ for 10s to 30s in a vacuum environment to ensure the formation of a high-quality alloy layer. The heating and cooling rates can be adjusted appropriately based on actual conditions. Moreover, the vacuum eutectic welding process can effectively improve the hermeticity of the all-inorganic packaging structure while avoiding the use of resin-based organic materials, thus extending the hermeticity and reliability of the ultraviolet device. It is understood that the reaction conditions for the vacuum eutectic welding can be flexibly adjusted based on the materials selected for the metal layer and the solder layer 7.

[0089] The present invention will be further described below with reference to specific embodiments:

[0090] Example 1

[0091] This embodiment provides an all-inorganic packaging structure for an ultraviolet device. Please refer to [link / reference]. Figures 1-6 The device includes: a substrate; a dam support with a cavity disposed around the substrate; at least one ultraviolet chip disposed on the substrate, the ultraviolet chip being located within the cavity of the dam support; and a light window cover adapted to the dam support.

[0092] The substrate has two sets of pads, each set located on the top and bottom sides of the substrate and electrically connected via conductive vias. A gap exists between the two sets of pads. The UV chip is placed on both sets of pads. The substrate also has a pair of electrodes, including a first electrode and a second electrode, respectively disposed on the two sets of pads. The UV chip and the electrodes are electrically connected via bonding wires to enable the UV chip to emit light. At least one protective element is also provided on the substrate, connected in parallel with the UV chip.

[0093] The top of the dam support has a limiting groove for placing the light window cover plate. The light window cover plate is placed in the limiting groove of the dam support, and the light window cover plate and the dam support are hermetically welded through an alloy layer. The contact surface between the dam support and the light window cover plate has a second metal layer, which is a Ti / Au layer. The light window cover plate is a metallized light window with a first metal layer, which is also a Ti / Au layer. The solder sheet layer is fixed to the groove by flux. The flux is applied to the limiting groove in four places. The solder sheet layer is an Au / Si solder sheet layer with a eutectic temperature of about 300°C.

[0094] This embodiment also provides a packaging method for the all-inorganic packaging structure of the ultraviolet device, including:

[0095] (1) An ultraviolet chip is disposed on the front side of the substrate;

[0096] (2) A dam support with a cavity and a limiting groove is formed on the front side of the substrate, so that the ultraviolet chip is located in the cavity of the dam support;

[0097] (3) A second metal layer is formed on the contact surface between the limiting groove and the light window cover.

[0098] (4) Apply flux to the second metal layer and place solder pads to form a solder pad layer;

[0099] (5) A metallized optical window cover plate is placed on the solder sheet layer and vacuum eutectic welding is performed to obtain the all-inorganic packaging structure of the ultraviolet device.

[0100] The vacuum eutectic welding temperature is 300℃ and the time is 20s.

[0101] In this embodiment, vacuum eutectic welding was employed, and X-ray tomography was used to perform the CT scan. The CT scan image is shown below. Figure 13 As shown, there are almost no white dots at the seal, indicating that almost no air bubbles are generated at the seal, thus preventing the formation of leakage channels and ensuring the good airtightness of the ultraviolet device. Subsequently, a helium mass spectrometer was used to measure the total amount of leaked gas, and the leak rate was calculated (the smaller the value, the higher the airtightness). The leak rate was only 9.6*10. -7 mbar*L / s.

[0102] control group

[0103] This control group provides an all-inorganic packaging structure for an ultraviolet device, which is the same as that in Example 1.

[0104] The difference from Example 1 lies in the preparation method; in step (5), eutectic welding was not performed in a vacuum environment. Specifically,

[0105] (5) Place a metallized optical window cover plate on the solder sheet layer and perform eutectic welding to obtain the all-inorganic packaging structure of the ultraviolet device;

[0106] The eutectic welding temperature is 300℃ and the time is 20s.

[0107] No vacuum treatment was performed during eutectic welding. X-ray tomography was used to analyze the process, and the CT scan image is shown below. Figure 14 As shown, some white dots, which are air bubbles, can be seen at the seal. These bubbles can create numerous leakage channels, thus reducing the airtightness of the UV device. Subsequently, a helium mass spectrometer was used to measure the total amount of leaked gas, and the leak rate was calculated (the smaller the value, the higher the airtightness). The leak rate reached 1.8*10^6. -6 mbar*L / s.

[0108] As can be seen, in this invention, the airtight welding of the light window cover and the dam support is achieved through an alloy layer. The alloy layer is formed by eutectic bonding of a metal layer and a solder sheet layer. Specifically, the ultraviolet device prepared by vacuum eutectic welding not only reduces costs, but also achieves airtightness comparable to that of ultraviolet devices prepared by traditional laser welding processes. Moreover, compared with ultraviolet devices prepared by conventional atmospheric pressure eutectic welding processes, vacuum eutectic welding can effectively reduce leakage rate, reduce the generation of leakage channels, and effectively improve its airtightness and reliability.

[0109] Example 2

[0110] This embodiment provides an all-inorganic packaging structure for an ultraviolet device, which is the same as the structure in Embodiment 1, except that:

[0111] The thickness of the first metal layer is 5 μm, the thickness of the second metal layer is 5 μm, the thickness of the solder pad layer is 50 μm, the outer width of the limiting groove is W1, the width of the light window cover is W2, and W1-W2=75 μm; the outer width of the first metal layer is W3, the inner width of the first metal layer is W4, and (W3-W4) / 2=200 μm; the inner width of the solder pad layer is W5, the outer width is W6, and 0.5(W6-W5)=200 μm; the distance between the outer edge of the solder pad layer and the outer edge of the limiting groove is W1-W6=80 μm.

[0112] The airtightness of the ultraviolet device obtained in this embodiment is comparable to that of Example 1, with almost no bubbles generated at the seal. Subsequently, the total amount of leaked gas was measured using a helium mass spectrometer leak detector, and the leak rate was calculated (the smaller the value, the higher the airtightness). The leak rate was only 1.0*10. -8 mbar*L / s. It is evident that the allowance provided on the limiting groove can further improve the leakage rate of the all-inorganic packaging structure of the ultraviolet device.

[0113] Example 3

[0114] This embodiment provides an all-inorganic packaging structure for an ultraviolet device, which is basically the same as that in Embodiment 2, except that:

[0115] The limiting groove has four allowance portions for placing the light window cover plate, such as... Figure 7 As shown, the allowance portion is a rounded groove, the shortest distance from the edge of the allowance portion to the outer edge of the dam support is d4, and the distance between the outer edge of the limiting groove and the outer edge of the dam support is d2, where d4 = 0.45d2.

[0116] Accordingly, in step (2), a dam support with a cavity and a limiting groove is formed on the front side of the substrate, so that the ultraviolet chip is located in the cavity of the dam support. Then, the fiber groove is processed to form a margin portion with a rounded corner groove shape.

[0117] The airtightness of the ultraviolet device obtained in this embodiment is comparable to that of Example 1, with almost no bubbles generated at the seal. Subsequently, the total amount of leaked gas was measured using a helium mass spectrometer leak detector, and the leak rate was calculated (the smaller the value, the higher the airtightness). The leak rate was only 1.1*10. -8 mbar*L / s. It is evident that the allowance provided on the limiting groove can further improve the leakage rate of the all-inorganic packaging structure of the ultraviolet device.

[0118] Example 4

[0119] This embodiment provides an all-inorganic packaging structure for an ultraviolet device, which is basically the same as that in Embodiment 3, except that:

[0120] A curved structure is formed on the edge of the limiting groove. Specifically, a protruding structure is formed on the outer edge of the limiting groove, and this protruding structure is located between two flux points, such as... Figure 8 and Figure 9 As shown, the maximum bending width of the bending structure is d1 = 0.4d2, the maximum bending length of the bending structure is d3, and the outer width of the limiting groove is W1, d3 = 0.85W1.

[0121] The airtightness of the ultraviolet device obtained in this embodiment is comparable to that of Example 1, with almost no bubbles generated at the seal. Subsequently, a helium mass spectrometer was used to measure the total amount of leaked gas, and the leak rate was calculated (the smaller the value, the higher the airtightness). The leak rate was only 1.3*10. -7 mbar*L / s. It is evident that the allowance provided on the limiting groove can further improve the leakage rate of the all-inorganic packaging structure of the ultraviolet device.

[0122] Example 5

[0123] This embodiment provides an all-inorganic packaging structure for an ultraviolet device, which is basically the same as that in Embodiment 2, except that:

[0124] A curved structure is formed on the edge of the limiting groove. Specifically, a recessed structure is formed on the inner edge of the limiting groove, and this recessed structure is located between two flux points, such as... Figure 10 and Figure 11 As shown, the maximum bending width of the bending structure is d1 = 0.4d2, the maximum bending length of the bending structure is d3, and the outer width of the limiting groove is W1, d3 = 0.25W1.

[0125] The airtightness of the ultraviolet device obtained in this embodiment is comparable to that of Example 1, with almost no bubbles generated at the seal. Subsequently, the total amount of leaked gas was measured using a helium mass spectrometer leak detector, and the leak rate was calculated (the smaller the value, the higher the airtightness). The leak rate was only 1.1*10. -8 mbar*L / s. It is evident that the allowance provided on the limiting groove can further improve the leakage rate of the all-inorganic packaging structure of the ultraviolet device.

[0126] The above description is merely a preferred embodiment of the present invention and should not be construed as limiting the scope of the invention. Therefore, any equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. A fully inorganic packaging structure for an ultraviolet device, characterized in that, include: substrate; A cavity-filled dam support is provided around the substrate; At least one ultraviolet chip is disposed on the substrate, and the ultraviolet chip is located within the cavity of the dam support; A light window cover plate adapted to the dam support frame; The top of the dam support has a limiting groove for placing the light window cover plate. The light window cover plate is placed in the limiting groove of the dam support, and the light window cover plate and the dam support are airtightly welded by an alloy layer. The alloy layer is formed by eutectic bonding of a metal layer and a solder sheet layer. The metal layer includes a first metal layer and a second metal layer. The first metal layer is disposed on the side of the light window cover plate near the limiting groove, and the second metal layer is disposed on the side of the limiting groove near the light window cover plate. The solder sheet layer is disposed between the first metal layer and the second metal layer. At least one allowance portion for placing the light window cover is formed on the limiting groove; a curved structure is formed on the edge of the limiting groove; The curved structure is either a raised structure or a recessed structure; The maximum bending width of the bending structure is d1, and the distance between the outer edge of the limiting groove and the outer edge of the dam support is d2, where d1 < 0.5d2. The maximum bending length of the bending structure is d3, and the outer width of the limiting groove is W1, where d3 < 0.5W1 or 0.7W1 < d3 < W1.

2. The all-inorganic packaging structure of the ultraviolet device as described in claim 1, characterized in that, The thickness ratio of the first metal layer to the solder layer is 1:(2~400).

3. The all-inorganic packaging structure of the ultraviolet device as described in claim 1 or 2, characterized in that, The thickness ratio of the first metal layer to the second metal layer is 1:(1~10). The thickness of the first metal layer is 0.2 μm to 10 μm; The thickness of the solder sheet layer is 20μm to 80μm.

4. The all-inorganic packaging structure of the ultraviolet device as described in claim 1, characterized in that, The metal layer includes at least an Au layer.

5. The all-inorganic packaging structure of the ultraviolet device as described in claim 1 or 4, characterized in that, The metal layer is one of Au layer, Ti layer / Au layer, and Ti layer / Ni layer / Au layer; The solder pad layer is one of Au / Si solder pad layer and Sn / Sb solder pad layer, the eutectic temperature of the solder pad layer is 240℃~340℃, and the solder pad layer is fixed on the groove by flux.

6. The all-inorganic packaging structure of the ultraviolet device as described in claim 1, characterized in that, The outer width of the limiting groove is W1, the width of the light window cover is W2, the outer width of the first metal layer is W3, the inner width of the first metal layer is W4, the inner width of the solder sheet layer is W5, and the outer width of the solder sheet layer is W6, satisfying W1-W3>W1-W6≥W1-W2; The width (W3-W4) / 2 of the first metal layer is 100μm to 300μm; The distance (W2-W3) / 2 between the outer edge of the first metal layer and the edge of the light window cover plate is 10μm to 50μm; The distance (W1-W6) / 2 between the outer edge of the solder sheet layer and the outer edge of the limiting groove is 30μm to 50μm; The width (W6-W5) / 2 of the solder pad layer is 150μm to 300μm.

7. A packaging method for an all-inorganic packaging structure of an ultraviolet device as described in any one of claims 1-6, characterized in that, include: An ultraviolet chip is placed on the front side of the substrate; A dam support with a cavity and a limiting groove is formed on the front side of the substrate, so that the ultraviolet chip is located in the cavity of the dam support, and a margin and a bending structure are formed on the limiting groove. A first metal layer is formed on the light window cover plate, and a second metal layer is formed on the limiting groove; A solder sheet is placed on the first metal layer to form a solder sheet layer; A light window cover is placed on the solder sheet layer, so that the solder sheet layer and the second metal layer are positioned opposite each other. An alloy layer is formed by eutectic welding. The light window cover and the dam support are welded together to obtain the all-inorganic packaging structure of the ultraviolet device.

8. The packaging method for the all-inorganic packaging structure of ultraviolet devices as described in claim 7, characterized in that, The eutectic welding is vacuum eutectic welding, which includes: maintaining a high temperature of 240℃~340℃ for 10s~30s in a vacuum environment.

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