All-inorganic packaging structure and packaging method of ultraviolet device

Abstract

The invention relates to the technical field of LED packaging, and discloses a full-inorganic packaging structure and packaging method of an ultraviolet device, the full-inorganic packaging structure comprises a substrate, a box dam support, an ultraviolet chip and a light window cover plate, a limiting groove used for placing the light window cover plate is formed in the top end of the box dam support, and the ultraviolet chip is arranged in the limiting groove. The light window cover plate is placed in a limiting groove of the box dam support, airtight welding of the light window cover plate and the box dam support is achieved through an alloy layer, the alloy layer is formed by eutectic bonding of a metal layer and a soldering lug layer, and packaging of an ultraviolet device is achieved through interaction between the metal layer and the soldering lug layer. According to the ultraviolet device, the packaging cavity is filled with the ultraviolet chip, impurities do not exist in the packaging cavity, the light-emitting performance of the ultraviolet chip is well protected, the ultraviolet device is good in air tightness, good in weather resistance and high in reliability, and the cost can be reduced.

Description

Technical Field

[0001] The invention relates to the technical field of LED packaging, and in particular to a full inorganic packaging structure and packaging method of an ultraviolet device. Background Art

[0002] UV devices, especially deep UV devices, have high photon energy, so conventional organic silicone materials cannot be used as encapsulation glue during packaging. Therefore, sapphire and quartz glass are often used as optically transparent materials for device packaging in UV device packaging, but quartz and sapphire materials are both high-temperature preparation materials, so they can only be prepared before being used in the packaging process, and cannot be cured during the packaging process like organic silicone materials, so that the optically transparent material is completely attached to the chip surface.

[0003] At present, there are two main methods for packaging ultraviolet devices using quartz windows or sapphire windows as optical transmission materials: one is semi-inorganic packaging, that is, bonding the quartz window or sapphire window to the dam through resin glue; the other is full inorganic packaging, that is, combining the quartz window or sapphire window with a metal frame, and then welding the metal frame and the dam through laser welding or other methods. However, both methods have certain defects. In the semi-inorganic packaging method, since the material used is a resin organic material, and the chemical bonds such as carboxyl (-COOH) contained in the resin organic material are prone to photolysis under deep ultraviolet light irradiation, long-term exposure to ultraviolet light in the application of ultraviolet devices may cause discoloration and aging, thereby affecting reliability, and the welding method in the full inorganic packaging is prone to high costs. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a fully inorganic packaging structure and packaging method for an ultraviolet device, the ultraviolet device has good airtightness, high reliability and reduced cost.

[0005] In order to solve the above technical problems, the first aspect of the present invention provides a fully inorganic packaging structure of an ultraviolet device, comprising:

[0006] substrate;

[0007] A dam support having a cavity and arranged around the substrate;

[0008] at least one ultraviolet chip disposed on the substrate, wherein the ultraviolet chip is located in the cavity of the dam support;

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

[0010] A limiting groove for placing the light window cover plate is formed at the top end of the dam support, 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 through an alloy layer, wherein the alloy layer is formed by eutectic bonding of a metal layer and a welding sheet layer;

[0011] The metal layer includes a first metal layer and a second metal layer, the first metal layer is arranged on the side of the light window cover plate close to the limiting groove, the second metal layer is arranged on the side of the limiting groove close to the light window cover plate, and the welding sheet layer is arranged between the first metal layer and the second metal layer.

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

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

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

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

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

[0017] As an improvement of the above solution, the thickness ratio of the first metal layer to 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 20 μm to 80 μm.

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

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

[0022] The solder sheet layer is one of an Au / Si solder sheet layer and a Sn / Sb solder sheet layer, the eutectic temperature of the solder sheet layer is 240° C. to 340° C., and the solder sheet layer is fixed on the groove by flux.

[0023] As an improvement of 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 of the first metal layer (W3-W4) / 2 is 100 μm to 300 μm;

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

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

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

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

[0029] A UV chip is arranged on the front side of the substrate;

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

[0031] Forming a first metal layer on the light window cover plate, and forming a second metal layer on the limiting groove;

[0032] Placing a solder pad on the first metal layer to form a solder pad layer;

[0033] A light window cover is placed on the soldering sheet layer so that the soldering sheet layer and the second metal layer are arranged opposite to each other, and an alloy layer is formed by eutectic welding. The light window cover and the dam bracket are welded together to obtain a fully inorganic packaging structure of the ultraviolet device.

[0034] As an improvement of the above solution, the eutectic welding is vacuum eutectic welding, and the vacuum eutectic welding includes: maintaining a high temperature environment of 240° C. to 340° C. for 10 seconds to 30 seconds in a vacuum environment.

[0035] The implementation of the present invention has the following beneficial effects:

[0036] In the present application, the fully inorganic packaging structure of the ultraviolet device includes a substrate, a dam bracket, an ultraviolet chip, and a light window cover. The top end of the dam bracket is formed with a limiting groove for placing the light window cover. The light window cover is placed in the limiting groove of the dam bracket, and the airtight welding of the light window cover and the dam bracket is achieved through an alloy layer, wherein the alloy layer is formed by eutectic bonding of a metal layer and a solder sheet layer. The packaging of the ultraviolet device is achieved by utilizing the interaction between the metal layer and the solder sheet layer, so that there are no impurities in the packaging cavity, thereby well protecting the luminescence performance of the ultraviolet chip, and the ultraviolet device has good airtightness, good weather resistance, high reliability, and can reduce costs. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0038] Figure 2 : Figure 1 Schematic cross-sectional view of ;

[0039] Figure 3 : Figure 2 A partial enlarged view of the middle A;

[0040] Figure 4 : A schematic diagram of the structure of Example 1 of the present invention when the light window cover is not packaged;

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

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

[0043] Figure 7 : A schematic diagram of the structure of Example 2 of the present invention when the light window cover is not packaged;

[0044] Figure 8 : A schematic diagram of the structure of Example 3 of the present invention when the light window cover is not packaged;

[0045] Fig. 9 : A schematic diagram of the structure of the solder sheet layer of Example 3 of the present invention;

[0046] Fig.10 : A schematic diagram of the structure of Example 4 of the present invention when the light window cover is not packaged;

[0047] Fig.11 : A schematic diagram of the structure of the solder sheet layer of Example 4 of the present invention;

[0048] Fig.12 : A schematic diagram of the structure after a soldering flux is arranged in the limiting groove of the dam support in the present invention;

[0049] Fig.13 : A CT scan of the all-inorganic packaging structure of the ultraviolet device provided in Example 1 of the present invention;

[0050] Fig.14 : CT scanning diagram of the all-inorganic packaging structure of the ultraviolet device provided by the control group of the present invention.

[0051] Reference numerals:

[0052] 1-substrate; 2-dam bracket; 3-UV chip; 4-light window cover; 5-limiting groove; 6-first metal layer; 7-solder sheet layer; 8-solder pad; 9-remainder part; 10-bending structure; 11-flux. DETAILED DESCRIPTION

[0053] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail with specific embodiments below.

[0054] In the description of the present application, it is necessary to understand that the orientations or positional relationships indicated by “upper”, “lower”, “top”, “bottom”, “inside”, “outside”, etc. are all based on the orientations or positional relationships shown in the accompanying drawings. The purpose is only to facilitate the description of the present invention and simplify the description. It does not indicate or imply that the referred parts must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0055] The full inorganic packaging of the ultraviolet device mainly welds the light window cover 4 and the dam bracket 2 together to achieve the sealing of the ultraviolet chip. The conventional light window cover 4 adopts a metallized light window cover, and the dam bracket 2 has a metal layer, which can be directly welded and sealed with solder paste. However, through many experiments, it is found that some organic components contained in the solder paste will be sealed in the cavity of the ultraviolet device after sealing, causing the luminous performance of the ultraviolet device to be greatly reduced. Therefore, the welding method using liquid solder paste cannot be widely used.

[0056] In order to solve the above problems, the present invention provides a first aspect of a fully inorganic packaging structure of a UV device, see Figure 1 , comprising: a substrate 1; a dam support 2 with a cavity arranged around the substrate 1; at least one ultraviolet chip 3 arranged on the substrate 1, and the ultraviolet chip 3 is located in the cavity of the dam support 2; and a light window cover 4 adapted to the dam support 2.

[0057] See also Figure 2, the substrate 1 is provided with pads 8, the number of the pads 8 is two groups, each group of the pads 8 is located on the upper and lower sides of the substrate 1, and can be electrically connected through conductive holes, there is a gap between the two groups of pads 8, the ultraviolet chip 3 is placed on the two groups of pads 8 at the same time, and optionally, the ultraviolet chip 3 is fixed on the pads 8 by welding material. At least one pair of electrodes is also provided on the substrate 1, each pair of electrodes includes a first electrode and a second electrode, the first electrode and the second electrode are respectively provided on the two groups of pads 8, and the ultraviolet chip 3 and the electrodes are electrically connected to realize the light emission of the ultraviolet chip 3. In some embodiments, the first electrode and the second electrode can be fixed on the corresponding pads 8 by welding materials, and the welding materials include but are not limited to gold-tin alloy; bonding wires are provided between the ultraviolet chip 3 and the electrodes to achieve electrical connection, and the bonding wires can be one or a mixture of gold wire, copper wire, silver wire, aluminum wire, gold-clad silver wire, and alloy wire.

[0058] Optionally, at least one protection element is also provided on the substrate 1, and the protection 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. Exemplary protection elements include antistatic protection elements, overvoltage protection elements, capacitor protection elements, etc.

[0059] It can be understood that the substrate 1 can be a ceramic substrate, and the substrate 1 can be square, rectangular or circular. The dam bracket 2 can be arranged around the substrate 1 by a welding process to form a cavity structure that wraps the substrate 1, or the dam bracket 2 is integrally formed with the substrate 1. The light window cover plate 4 is made of an optically transparent material with high ultraviolet light transmittance, and the light window cover plate 4 can be quartz, sapphire, or of course other materials. The present invention is not limited to this, and any corresponding material implementation form is within the protection scope of the present invention.

[0060] See also Figure 3The top end of the dam support 2 is formed with 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 airtight welding of the light window cover plate 4 and the dam support 2 is achieved through an alloy layer (not marked in the figure), wherein the alloy layer is formed by eutectic bonding of a metal layer and a soldering sheet layer 7, the metal layer includes a first metal layer 6 and a second metal layer (not marked in the figure), the first metal layer 6 is arranged on the side of the light window cover plate 4 close to the limiting groove 5, the second metal layer is arranged on the side of the limiting groove 5 close to the light window cover plate 4, and the soldering sheet layer 7 is arranged between the first metal layer 6 and the second metal layer. In the present application, the metal layer and the solid soldering sheet layer 7 interact with each other to achieve the packaging of the ultraviolet device, avoid the use of solder paste, and make the packaging cavity free of impurities, thereby well protecting the luminous performance of the ultraviolet chip, and the ultraviolet device has good airtightness, good weather resistance, high reliability, and can reduce costs.

[0061] Preferably, the thickness ratio of the first metal layer 6 to the solder sheet layer 7 is 1: (2-400), and an alloy layer with a small void rate is formed between the first metal layer 6 and the solder sheet layer 7, so as to realize the connection between the first metal layer 6 and the solder sheet layer 7, and the bonding force between the first metal layer 6 and the light window cover plate 4 is strong, so that the air tightness of the ultraviolet device is improved. In some embodiments, the thickness of the first metal layer 6 is 0.2 μm to 10 μm, and can be 0.2 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, etc., but not limited thereto. If the thickness of the first metal layer 6 is less than 0.2 μm, it is easy to cause the peeling between the first metal layer 6 material and the light window cover plate 4 after packaging. If the thickness of the first metal layer 6 is greater than 10 μm, it is easy to cause the unevenness of the first metal layer 6 after packaging, thereby causing the air tightness to decrease. In some embodiments, the thickness of the solder sheet layer 7 is 20 μm to 80 μm. If the thickness of the solder sheet layer 7 is less than 20 μm, it will easily cause difficulty in picking up and self-supporting during the process, and less welding raw materials will cause voids in some welding areas, and a welding layer cannot be formed on the entire welding surface, resulting in a decrease in the airtightness of the package; but if the thickness of the solder sheet layer 7 is greater than 80 μm, it will cause an increase in cost, and some solder sheet materials cannot form alloys with the upper and lower welding surfaces, which will also cause a decrease in reliability.

[0062] See also Figure 4 and Figure 5, the outer width of the limiting groove 5 is W1, and the width of the light window cover plate 4 is W2. In order to facilitate the installation of the light window cover plate 4, W1>W2 is set so that there is a certain gap between the light window cover plate 4 and the limiting groove 5, and the distance of the gap is 0.5(W1-W2); more preferably, W1-W2=50μm~100μm, exemplarily 50μm, 55μm, 60μm, 65μm, 70μm, etc., but not limited to this. If the gap between the light window cover plate 4 and the limiting groove 5 is too large, the entire light window cover plate 4 is easily offset to one side or one corner of the package body after packaging, 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 affected by the position accuracy and angle accuracy of the equipment during the process of processing and placement, and cannot be placed in the limiting groove 5. Optionally, a metal layer (not shown in the figure) can be provided in the gap between the light window cover plate 4 and the limiting groove 5 to increase the sealing performance between the side wall of the light window cover plate 4 and the dam support 2 , and the metal layer here includes but is not limited to an Au layer.

[0063] See also Figure 5 , the first metal layer 6 is arranged on the side of the light window cover plate 4 close to the limiting groove. It can be that the first metal layer 6 is arranged on the light window cover plate 4 to form a metallized light window, and then the first metal layer 6 is used to form an alloy layer by eutectic bonding with the solder layer 7 to realize the full inorganic packaging 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 by 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, having better chemical stability and corrosion resistance, and can meet the performance requirements of ultraviolet devices in a variety of applicable environments. Further 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 on the light window cover plate 4 due to the large difference in expansion coefficient between the first metal layer 6 and the light window cover plate 4. 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 first metal layer 6 is a Ti layer / Au layer, a Ti layer / Ni layer / Au layer.

[0064] Furthermore, the first metal layer 6 has an inner edge close to the luminous center and an outer edge away from the luminous center, the distance between the two inner edges is the inner width of the first metal layer 6, 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, the inner width of the first metal layer 6 is W4, the width of the first metal layer 6 is 100μm~300μm, that is, (W3-W4) / 2=100μm~300μm, which is convenient for forming a sufficient welding surface with the welding sheet layer 7 and will not affect the light effect during ultraviolet period. The width of the first metal layer 6 can be 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, etc., but it is not limited thereto. If the width of the first metal layer 6 is less than 100 μm, the welding reliability and air tightness 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 300 μm, the first metal layer 6 will excessively block the area of ​​the central light-transmitting region, thereby causing a reduction in 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 4 is 10 μm to 50 μm, that is, (W2-W3) = 20 μm to 100 μm, which can not only prevent the first metal layer 6 from being damaged and peeled off when cutting a small piece of the metalized light window during the processing of the metalized light window, but also avoid the metal area being too narrow, or the metal area being too close to the center, reducing the light-transmitting area, and causing a reduction in the light efficiency of the overall packaged device. The distance between the outer edge of the first metal layer 6 and the edge of the light window cover 4 is exemplarily 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, etc., but is not limited thereto.

[0065] The second metal layer is arranged on the side of the limiting groove 5 close to the light window cover plate 4, and the second metal layer may be arranged on the contact surface between the limiting groove 5 and the light window cover plate 4 to form a dam bracket with a metal layer. Preferably, the second metal layer may be a single-layer structure or a multi-layer structure, preferably including at least an Au layer. Further preferably, the second metal layer is a transition metal layer and an Au layer, and 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 layer / Au layer, a Ti layer / Ni layer / Au layer, and the composition of the first metal layer 6 and the second metal layer may be the same or different. The thickness ratio of the first metal layer to the second metal layer is 1:(1 to 10), and a good alloy layer can be formed between the first metal layer 6 and the second metal layer using a solder sheet layer 7. In some embodiments, the thickness of the second metal layer is 1 μm to 100 μm.

[0066] It is understandable that if the preparation material of the dam bracket 2 and / or the light window cover 4 includes Au-Sn alloy, the use of the welding layer 7 can be avoided, and the light window cover 4 and the dam bracket 2 can be directly welded together to achieve the sealing of the UV chip. However, no relevant suitable material has been found so far, and the use of this material will make the cost very high.

[0067] See also Figure 6 , the soldering sheet layer 7 is an annular layer structure adapted to the first metal layer 6, having an inner edge close to the luminous center and an outer edge away from the luminous center. The soldering sheet layer 7 is fixed on the groove by the flux 11, and the flux 11 can activate the welding surface to make the welding quality of the metal layer and the soldering sheet layer 7 better. The flux 11 can be dotted on the limiting groove 5, or evenly coated on the groove. In order to reduce the production cost, the flux 11 can be dotted on the limiting groove 5, and the number of dots of the flux 11 can be 3 to 6. The eutectic temperature of the soldering sheet layer 7 is 240℃~340℃. If the eutectic temperature of the soldering sheet layer 7 is higher than 340℃, it is easy to cause the secondary melting of the eutectic layer of the internal chip, resulting in a decrease in reliability. If the eutectic temperature of the soldering sheet layer 7 is lower than 240℃, it will affect the subsequent application of the package and may cause insufficient reliability of welding during the working process. Exemplarily, the solder sheet layer 7 is one of an Au / Si solder sheet layer and a Sn / Sb solder sheet layer. Of course, the solder sheet layer 7 may also be a layer structure formed by other materials. The present invention is not limited to this, and any corresponding material implementation form is within the protection scope of the present invention.

[0068] Furthermore, the width of the soldering sheet layer 7 is slightly larger than the width of the first metal layer 6 to ensure the formation of the metal soldering layer. Specifically, the distance between the two inner edges of the soldering sheet layer 7 is the inner width of the soldering sheet layer 7, and the distance between the two outer edges is the outer width of the soldering sheet layer 7. The inner width of the soldering sheet layer 7 is W5, and the outer width is W6. The width of the soldering sheet layer 7 is 150 μm to 300 μm, that is, (W6-W5) / 2=150 μm to 300 μm. If the width of the soldering sheet layer 7 is less than 150 μm, it will also cause the welding reliability and air tightness to decrease. However, controlling the width of the soldering sheet layer 7 to be less than 300 μm can avoid the soldering sheet layer 7 from excessively blocking the area of ​​the central light-transmitting area, thereby avoiding the reduction of 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, that is, W1-W6=60μm to 100μm, which not only facilitates the smooth placement of the light window cover 4, but also can accurately control the sealing position of the light window cover 4, so that the light window cover 4 and the dam bracket 2 can be directly welded.

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

[0071] According to another embodiment of the present invention, at least one margin portion 9 for placing the light window cover plate 4 is formed on the limiting groove 5. Figure 7 As shown, the light window cover plate 4 and the solder sheet layer 7 are prevented from being offset during the process and cannot be placed normally in the limiting groove 5. The setting of the margin part 9 can improve the process yield. At the same time, the margin part 9 can also store more flux during the setting process of the flux 11 to prevent the problem of poor eutectic quality caused by insufficient flux in eutectic welding, thereby affecting the air tightness. It can be understood that the margin part 9 can be a rounded groove, and of course it can also be a structure of other shapes. The present invention is not limited to this, and any corresponding structural implementation form is within the protection scope of the present invention.

[0072] Furthermore, the shortest distance from the edge of the margin to the outer edge of the dam bracket is d4, the distance between the outer edge of the limiting groove and the outer edge of the dam bracket is d2, d4<0.5d2, so that the limiting groove 5 maintains a certain thickness, thereby ensuring the reliability of the dam bracket 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 solder flux 11 points, which can increase the thickness of the solder sheet layer 7, improve the welding effect between the first metal layer 6 and the solder sheet layer 7, and prevent the middle part from breaking during the eutectic process between the first metal layer 6 and the solder sheet layer 7, resulting in poor eutectic welding effect in the middle area, thereby avoiding the problem of air tightness and reducing the packaging cost of the ultraviolet device. The curved structure 10 is a convex structure or a concave structure, which can not only maintain the supporting effect of the limiting groove 5 on the light window cover 4, but also increase the thickness of the solder sheet layer 7 as much as possible. In order to avoid reducing the light efficiency of the ultraviolet device due to the setting of the curved structure 10, the distance between the outer edge of the limiting groove 5 and the outer edge of the dam bracket 2 is d2, and d2 is controlled to be less than 0.5W4.

[0074] In some embodiments, a protrusion structure is formed on the outer edge of the limiting groove 5, and the protrusion structure is located between two soldering flux points 11, such as Figure 8 and Fig. 9As shown, the maximum bending width of the bending structure 10 is d1, d1<0.5d2. If the maximum bending width of the bending structure 10 is too large, the reliability of the dam support 2 will be reduced; the maximum bending length of the bending structure 10 is d3, 0.7W1<d3<W1. In other embodiments, a concave structure is formed on the inner edge of the limiting groove 5, and the concave structure is located between the two soldering fluxes 11, such as Fig.10 and Fig.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 bracket 2 is d2, d1<0.5d2, the maximum bending length of the bending structure 10 is d3, d3<0.5W1, and if the maximum bending length d3 of the bending structure 10 is too large, it will affect the light output 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) A UV chip 3 is arranged on the front side of the substrate 1;

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

[0078] (2) forming a dam support 2 having a cavity and a limiting groove 5 on the front side of the substrate 1, so that the UV 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, and the structure formed is as follows: Figure 4 If the limiting groove 5 is formed with a margin portion 9 and / or a bending structure 10, they can also be formed in this step.

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

[0081] In this step, a metalized light window is formed after the first metal layer 6 is arranged on the light window cover plate 4, and then the metalized light window is contacted with the solder sheet layer 7 to realize the full inorganic packaging of the ultraviolet device. In the process of forming the metalized light window, the width W2 of the light window cover plate 4 is reasonably controlled to be smaller than the width of the limiting groove 5, so that there is 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~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) / 210μm~50μm. The first metal layer 6 can be formed on the light window cover plate 4 by a coating process.

[0082] The second metal layer is arranged on the side of the limiting groove 5 close to the light window cover 4. The second metal layer can be arranged on the contact surface between the limiting groove 5 and the light window cover 4, so that the second metal layer wraps the contact surface to form a dam bracket with a metal layer.

[0083] (4) placing a solder sheet on the first metal layer to form a solder sheet layer;

[0084] Specifically, a soldering flux 11 is disposed on the first metal layer, and then a solder sheet is placed to form a solder sheet layer 7;

[0085] In this step, the soldering flux 11 can be dotted on the limiting groove 5, or can be evenly coated on the groove. Under the same welding effect, in order to reduce the production cost, the soldering flux 11 can be dotted on the limiting groove 5. Fig.12 As shown; the number of points of the soldering flux 11 can be 3 to 6. Subsequently, the soldering sheet layer 7 is placed in the limiting groove 5, so that the soldering flux 11 is in full contact with the soldering sheet layer 7, and the soldering sheet layer 7 is fixed on the dam bracket 2. During the placement process, the distance between the outer edge of the soldering 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) placing a light window cover plate 4 on the soldering sheet layer 7 so that the soldering sheet layer 7 and the second metal layer are arranged opposite to each other, eutectic welding is performed to form an alloy layer, and the light window cover plate 4 and the dam bracket 2 are welded together to obtain a fully 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 by welding between the metal layer and the welding sheet layer 7, which reduces the welding temperature. In addition, the void rate in the formed alloy layer is low, thereby improving the airtightness of the ultraviolet device.

[0088] Furthermore, the vacuum eutectic welding includes: maintaining a high temperature environment of 240°C to 340°C for 10s to 30s in a vacuum environment to ensure the formation of a high-quality alloy layer, wherein the heating rate and the cooling rate can be reasonably adjusted according to actual conditions. Moreover, the vacuum eutectic welding process can effectively improve the airtightness of the all-inorganic packaging structure, while also avoiding the use of resin-based organic materials, and extending the airtightness and reliability of the ultraviolet device. It can be understood that the reaction conditions of the vacuum eutectic welding can be flexibly adjusted according to the selected materials of the metal layer and the solder layer 7.

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

[0090] Example 1

[0091] This embodiment provides a fully inorganic packaging structure for a UV device. Figure 1 to Figure 6 , comprising: a substrate; a dam support having a cavity arranged around the substrate; at least one ultraviolet chip arranged on the substrate, the ultraviolet chip being located in the cavity of the dam support; and a light window cover plate adapted to the dam support.

[0092] The substrate is provided with pads, and the number of the pads is two groups, each group of pads is located on the upper and lower sides of the substrate, and is electrically connected through conductive holes, and there is a gap between the two groups of pads, and the ultraviolet chip is placed on the two groups of pads at the same time. The substrate is also provided with a pair of electrodes, and the electrodes include a first electrode and a second electrode, and the first electrode and the second electrode are respectively provided on the two groups of pads, and the ultraviolet chip and the electrodes are electrically connected through bonding wires to realize the light emission of the ultraviolet chip. The substrate is also provided with at least one protection element, which is connected in parallel with the ultraviolet chip.

[0093] A limiting groove for placing the light window cover is formed at the top end of the dam bracket, the light window cover is placed in the limiting groove of the dam bracket, and the airtight welding of the light window cover and the dam bracket is achieved through the alloy layer. The contact surface between the dam bracket and the light window cover has a second metal layer, which is a Ti layer / Au layer. The light window cover is a metallized light window provided with a first metal layer, which is a Ti layer / Au layer. The solder sheet layer is fixed to the groove by flux, and the flux points are arranged on the limiting groove. The number of flux points is 4. The solder sheet layer is an Au / Si solder sheet layer, and the eutectic temperature is about 300°C.

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

[0095] (1) Arranging a UV chip on the front side of the substrate;

[0096] (2) forming a dam support having a cavity and a limiting groove on the front side of the substrate, so that the UV chip is located in the cavity of the dam support;

[0097] (3) forming a second metal layer on the contact surface between the limiting groove and the light window cover plate,

[0098] (4) applying flux on the second metal layer and placing a solder sheet to form a solder sheet layer;

[0099] (5) placing a metalized light window cover plate on the solder sheet layer and performing vacuum eutectic welding to obtain a fully inorganic packaging structure of the ultraviolet device;

[0100] The vacuum eutectic welding is performed at a temperature of 300° C. and for a time of 20 seconds.

[0101] In this embodiment, vacuum eutectic welding is used, and X-ray tomography is used to perform the tomography. The CT scan is shown in FIG. Fig.13 As shown in the figure, there are almost no white spots at the seal, that is, there are almost no bubbles at the seal, and no leakage channels will be formed, thus ensuring the good airtightness of the UV device. Subsequently, the total amount of leaked gas was measured using a helium mass spectrometer leak detector, and the leakage rate was calculated (the smaller the value, the higher the airtightness), and the leakage rate was only 9.6*10 -7 mbar*L / s.

[0102] Control group

[0103] This control group provides a fully inorganic packaging structure of an ultraviolet device, and its structure is the same as that of Example 1.

[0104] The difference from Example 1 is the preparation method. In step (5), eutectic welding is not performed under a vacuum environment. Specifically,

[0105] (5) placing a metalized light window cover plate on the soldering sheet layer and performing eutectic welding to obtain a fully inorganic packaging structure of the ultraviolet device;

[0106] The eutectic welding temperature is 300° C. and the welding time is 20 seconds.

[0107] No vacuum treatment was performed during eutectic welding. X-ray tomography was used to perform the CT scan. Fig.14 As shown in the figure, some white spots can be seen at the seal, which are bubbles, forming more leakage channels, thereby reducing the airtightness of the UV device. Subsequently, a helium mass spectrometer leak detector was used to measure the total amount of leaked gas and calculate the leakage rate (the smaller the value, the higher the airtightness). The leakage rate reached 1.8*10 -6 mbar*L / s.

[0108] It can be seen that in the present invention, the airtight welding of the light window cover and the dam bracket is achieved through the alloy layer, wherein the alloy layer is formed by eutectic bonding of the metal layer and the welding sheet layer. The ultraviolet device prepared by vacuum eutectic welding not only reduces the cost, but also has airtightness comparable to that of the ultraviolet device prepared by the traditional laser welding process. Moreover, compared with the ultraviolet device prepared by the conventional normal pressure eutectic welding process, vacuum eutectic welding can effectively reduce the leakage rate, reduce the generation of leakage channels, and effectively improve its airtightness and reliability.

[0109] Example 2

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

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

[0112] The air tightness of the UV device obtained in this embodiment is comparable to that in embodiment 1, and almost no bubbles are generated at the sealing part. Subsequently, the total amount of leaked gas is measured using a helium mass spectrometer leak detector, and the leak rate is calculated (the smaller the value, the higher the air tightness). The leak rate is only 1.0*10 -8 mbar*L / s. It can be seen that the margin portion 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 a fully inorganic packaging structure of an ultraviolet device, which is basically the same as that of Embodiment 2, except that:

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

[0116] Correspondingly, in step (2), a dam support having a cavity and a limiting groove is formed on the front side of the substrate so that the UV chip is located in the cavity of the dam support, and then the fiber groove is processed to form a residual portion in the shape of a rounded groove.

[0117] The air tightness of the UV device obtained in this embodiment is comparable to that in embodiment 1, and almost no bubbles are generated at the sealing part. Subsequently, the total amount of leaked gas is measured using a helium mass spectrometer leak detector, and the leak rate is calculated (the smaller the value, the higher the air tightness). The leak rate is only 1.1*10 -8 mbar*L / s. It can be seen that the margin portion 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 a fully inorganic packaging structure of an ultraviolet device, which is basically the same as that of Embodiment 3, except that:

[0120] A curved structure is formed on the edge of the limiting groove. Specifically, a convex structure is formed on the outer edge of the limiting groove, and the convex structure is located between two flux points. Figure 8 and Fig. 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, the outer width of the limiting groove is W1, and d3=0.85W1.

[0121] The air tightness of the UV device obtained in this embodiment is comparable to that in embodiment 1, and almost no bubbles are generated at the sealing part. Subsequently, the total amount of leaked gas is measured using a helium mass spectrometer leak detector, and the leak rate is calculated (the smaller the value, the higher the air tightness). The leak rate is only 1.3*10 -7 mbar*L / s. It can be seen that the margin portion 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 a fully inorganic packaging structure of an ultraviolet device, which is basically the same as that of Embodiment 2, except that:

[0124] A curved structure is formed on the edge of the limiting groove. Specifically, a concave structure is formed on the inner edge of the limiting groove, and the concave structure is located between two soldering flux points. Fig.10 and Fig.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, the outer width of the limiting groove is W1, and d3=0.25W1.

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

[0126] The above disclosure is only a preferred embodiment of the present invention, which certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to 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 dam support having a cavity and arranged around the substrate; at least one ultraviolet chip disposed on the substrate, wherein the ultraviolet chip is located in the cavity of the dam support; A light window cover plate adapted to the dam support; A limiting groove for placing the light window cover plate is formed at the top end of the dam support, 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 through an alloy layer, wherein the alloy layer is formed by eutectic bonding of a metal layer and a welding sheet layer; The metal layer includes a first metal layer and a second metal layer, the first metal layer is arranged on the side of the light window cover plate close to the limiting groove, the second metal layer is arranged on the side of the limiting groove close to the light window cover plate, and the welding sheet layer is arranged between the first metal layer and the second metal layer.

2. The all-inorganic packaging structure of the ultraviolet device according to claim 1, characterized in that: At least one margin portion for placing the light window cover is formed on the limiting groove; and a curved structure is formed on the edge of the limiting groove.

3. The all-inorganic packaging structure of the ultraviolet device according to claim 2, characterized in that: The curved structure is a convex structure or a concave structure; The maximum bending width of the bending structure is d1, the distance between the outer edge of the limiting groove and the outer edge of the dam support is d2, d1<0.5d2; The maximum bending length of the bending structure is d3, the outer width of the limiting groove is W1, d3<0.5W1, or 0.7W1<d3<W1.

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

5. The all-inorganic packaging structure of the ultraviolet device according to claim 1 or 4, 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 20 μm to 80 μm.

6. The all-inorganic packaging structure of the ultraviolet device according to claim 1, characterized in that: The metal layer includes at least an Au layer.

7. The all-inorganic packaging structure of the ultraviolet device according to claim 1 or 6, characterized in that: The metal layer is one of Au layer, Ti layer / Au layer, Ti layer / Ni layer / Au layer; The solder sheet layer is one of an Au / Si solder sheet layer and a Sn / Sb solder sheet layer, the eutectic temperature of the solder sheet layer is 240° C. to 340° C., and the solder sheet layer is fixed on the groove by flux.

8. The all-inorganic packaging structure of the ultraviolet device according to claim 2 or 3, 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 of the first metal layer (W3-W4) / 2 is 100 μm to 300 μm; The distance (W2-W3) / 2 between the outer edge of the first metal layer and the edge of the light window cover is 10 μm to 50 μm; The distance (W1-W6) / 2 between the outer edge of the soldering sheet layer and the outer edge of the limiting groove is 30 μm to 50 μm; The width of the solder sheet layer (W6-W5) / 2 is 150 μm to 300 μm.

9. A packaging method for the all-inorganic packaging structure of an ultraviolet device according to any one of claims 1 to 8, characterized in that: include: A UV chip is arranged on the front side of the substrate; A dam support having a cavity and a limiting groove is formed on the front side of the substrate, so that the UV chip is located in the cavity of the dam support; Forming a first metal layer on the light window cover plate, and forming a second metal layer on the limiting groove; Placing a solder pad on the first metal layer to form a solder pad layer; A light window cover is placed on the soldering sheet layer so that the soldering sheet layer and the second metal layer are arranged opposite to each other, and an alloy layer is formed by eutectic welding. The light window cover and the dam bracket are welded together to obtain a fully inorganic packaging structure of the ultraviolet device.

10. The packaging method of the all-inorganic packaging structure of the ultraviolet device according to claim 9, characterized in that: The eutectic welding is vacuum eutectic welding, and the vacuum eutectic welding includes: maintaining a high temperature environment of 240° C. to 340° C. for 10 seconds to 30 seconds in a vacuum environment.

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