Box dam capable of preventing welding flux from overflowing

Abstract

The utility model relates to the technical field of micro electro mechanical systems, in particular to a box dam for preventing solder from overflowing, which comprises a substrate, the periphery of the substrate extends upwards to form an extension part, the extension part is arranged in a surrounding manner, a cavity is formed in the extension part, and a chip is welded in the cavity; the cover plate is welded on the extension part and is of a square structure; the germanium window is welded on the cover plate along the outline of the outer edge of the germanium window; the cover plate body is provided with a box dam, the box dam extends upwards from the surface of the cover plate body, the projection of the inner boundary of the box dam falls outside the outer edge of the germanium window, and a continuously closed blocking surface is formed on the inner wall of the box dam so as to block the overflow of the welding flux. The box dam is arranged on the cover plate, the height of the box dam is higher than that of the cover plate, and the continuously closed blocking surface is formed on the inner wall surface of the box dam; the overflow of the welding flux in the welding process is effectively prevented, and the packaging quality is ensured.

Description

TECHNICAL FIELD

[0001] The utility model relates to micro electro mechanical system technical field, especially relate to a dam that prevents solder overflow. BACKGROUND

[0002] At present, the vacuum degree requirement of MEMS (micro electro mechanical system) devices such as infrared sensor and gyroscope is extremely strict, and these devices need to be packaged by brazing process through vacuum sealing and welding equipment in the manufacturing process. However, in the brazing process, due to technical limitations, the gas rapid cooling method cannot be used, and only natural cooling or water cooling method can be used for cooling. This cooling method is relatively slow, which leads to the combination time of brazing material being too long, and further causes the problem of solder overflow. The overflow of solder not only seriously affects the appearance quality of the device, but also leads to a high scrap rate.

[0003] In view of this problem, the main coping strategy in the industry at present is to optimize the brazing parameters. However, due to the complexity and uncontrollability of the brazing process, the effect of this optimization method is not significant, and it is difficult to completely avoid the phenomenon of solder overflow.

[0004] Therefore, the present application develops a dam that prevents solder overflow to solve the problems existing in the prior art. SUMMARY

[0005] The utility model aims at providing a dam that prevents solder overflow to solve the problem of solder overflow in the packaging process of micro electro mechanical system devices in the prior art.

[0006] The technical scheme of the utility model is: a dam that prevents solder overflow, comprising:

[0007] A substrate, which extends upward around the substrate to form an extension, the extension is arranged around and forms a cavity inside, and a chip is welded in the cavity;

[0008] A cover plate, which is welded on the extension and has a mouth-shaped structure;

[0009] A germanium window, which is welded on the cover plate along the outer edge contour of the germanium window;

[0010] A dam, which extends upward from the surface of the cover plate body, the inner boundary projection of the dam falls outside the outer edge of the germanium window, and the inner wall of the dam forms a continuous closed barrier surface to block the overflow of solder.

[0011] Preferably, the dam is a protrusion arranged on the upper surface of the cover plate, the height of the dam is higher than that of the cover plate, and there is no gap between the root of the dam and the upper surface of the cover plate.

[0012] Preferably, the dam is adjacent to the two side walls of the germanium window with a certain distance.

[0013] Preferably, the upper surface of the cover plate is provided with a mounting groove around the contour thereof, and the dam is arranged in the mounting groove, and the bottom surface of the dam is in contact with the bottom surface of the mounting groove.

[0014] Preferably, the barrier surface is a circular arc surface, or a plane perpendicular to the upper surface of the cover plate, or an inclined plane forming an included angle with the upper surface of the cover plate.

[0015] Preferably, the dam is fixedly connected with the upper surface of the cover plate by sintering or gluing, wherein the sintering is to melt and penetrate the dam material into the surface of the cover plate, and the gluing is to coat a polymer glue layer on the cover plate and solidify and form.

[0016] Compared with the prior art, the utility model has the advantages that:

[0017] (1) The dam is a convex structure arranged on the cover plate, the height of the dam is higher than that of the cover plate, and the inner wall surface of the dam forms a continuous closed barrier surface, which effectively prevents the overflow of the solder during welding and ensures the packaging quality.

[0018] (2) The dam is arranged in the mounting groove, so that the dam can be accurately installed along the contour of the cover plate, and the packaging problem caused by position deviation is avoided, and meanwhile, the bottom surface of the dam is in contact with the bottom surface of the mounting groove, so that the dam is stably supported and deformation or displacement of the dam during packaging is prevented.

[0019] (3) The barrier surface of the dam can be a circular arc surface, a vertical plane or an inclined plane, which can be customized according to the packaging requirement and the size of the chip, and different barrier surfaces are helpful to improve the heat dissipation performance of the packaging structure, so that the heat released when the solder is melted can be more effectively transferred to the outside of the packaging structure, and the temperature inside the packaging structure is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0020] The utility model will be further described in connection with the drawings and embodiments:

[0021] Figure 1 It is an explosion schematic view of the dam for preventing solder overflow according to the utility model;

[0022] Figure 2 It is a partial structure schematic view of one embodiment of the utility model;

[0023] Figure 3 It is a structure schematic view of the dam in embodiment one according to the utility model;

[0024] Figure 4 It is a structure schematic view of the dam in embodiment two according to the utility model;

[0025] Figure 5 The structure diagram of the dam in the third embodiment of the utility model is shown.

[0026] 1, base plate; 11, extension; 12, cavity; 2, cover plate; 21, groove; 3, germanium window; 4, dam; 41, blocking surface. DETAILED DESCRIPTION

[0027] The content of the utility model will be further explained in detail in combination with specific embodiments:

[0028] As Figure 1 shown, a dam for preventing solder overflow includes a base plate 1, a cover plate 2, a germanium window 3 and a dam 4 arranged on the cover plate 2. The base plate 1 serves as the basis of packaging, and its four edges extend upward to form an extension 11, which not only enhances the mechanical strength of the base plate 1, but also forms a cavity 12 inside the base plate 1, providing the necessary space for chip welding. The cover plate 2 is in the shape of a mouth, and is welded on the extension 11 of the base plate 1, thereby closing the cavity 12 inside the base plate 1 and ensuring the integrity and sealing of the packaging structure. The germanium window 3 is welded on the cover plate 2 along its contour, and is usually used to provide an optical access to observe or detect the state of the chip inside the package after packaging. The dam 4 extends upward from the surface of the cover plate 2 and makes the inner boundary of the dam 4 project outside the outer edge of the germanium window 3, so that the dam 4 completely surrounds the germanium window 3 and forms an additional barrier around it. The dam 4 is a protrusion arranged on the cover plate 2, and its height is higher than that of the cover plate 2. A continuous closed blocking surface 41 is formed on the inner wall of the dam 4, which effectively blocks the solder overflow during the welding process, thereby protecting the chips and other components inside the package from damage.

[0029] In actual welding process, the solder may flow due to high temperature. If the dam 4 is in close contact with the side wall of the germanium window 3, the solder may overflow and contact the germanium window 3, causing damage to the germanium window 3 or affecting its performance. Maintaining an appropriate distance between the dam 4 and the side wall of the germanium window 3 can make the welding operation more flexible and convenient, more easily control the flow direction and amount of solder, and ensure the quality of the welding joint. In addition, the germanium window 3 is an important component in the packaging structure, and its performance directly affects the overall performance of the packaged device. Maintaining an appropriate distance between the dam 4 and the side wall of the germanium window 3 can ensure that the germanium window 3 is not damaged during packaging, thereby maintaining its original performance.

[0030] Embodiment one:

[0031] As Figure 3As shown, the barrier surface 41 formed by the inner wall of the dam 4 is arc-shaped. During the welding process, the solder melts and flows when subjected to heat. The arc-shaped barrier surface 41 can guide the flow of the solder more smoothly, so that the solder can be distributed more evenly along this curved surface, reducing the risk of solder accumulation or overflow caused by poor flow.

[0032] Example 2:

[0033] like Figure 4 As shown, the barrier surface 41 formed by the inner wall of the dam 4 is a plane perpendicular to the upper surface of the cover plate 2. During the welding process, the plane barrier surface 41 can provide a clear and consistent solder blocking boundary. When the solder is subjected to heat, it will flow along this plane boundary, which is easier to control and guide, helps to reduce solder overflow and irregular flow, and ensures the accuracy and reliability of the encapsulation. At the same time, the design of the plane barrier surface 41 makes the manufacturing process of the dam 4 simpler and more direct, and easier to achieve through standard machining or injection molding processes, thereby reducing manufacturing costs and production cycle.

[0034] Example 3:

[0035] like Figure 5 As shown, the barrier surface 41 formed by the inner wall of the dam 4 is an inclined plane that forms an angle with the upper surface of the cover plate 2. The inclined plane allows the solder to flow along a predetermined path after melting, reducing solder overflow and irregular distribution, thereby improving the accuracy and reliability of the packaging. The adjustable angle of the inclined plane provides more flexibility for the packaging process. By adjusting the angle, it can accommodate chips of different sizes and shapes, as well as different packaging requirements.

[0036] To further explain, in practical applications, the dam structure 4 of the vertical plane barrier surface 41, the inclined plane barrier surface 41, and the arc-shaped barrier surface 41 can be customized according to packaging requirements and chip size, and all of them help to improve the heat dissipation performance of the packaging structure. During the soldering process, the heat released when the solder melts can be more effectively transferred to the outside of the packaging structure through different barrier surfaces 41, thereby reducing the temperature inside the packaging and improving the reliability and stability of the packaging.

[0037] In other implementations, such as Figure 2As shown, the upper surface of the cover plate 2 has a mounting groove 21 around its contour. A dam 4 is provided in the mounting groove 21, which allows the dam 4 to be precisely installed along the contour of the cover plate 2, avoiding encapsulation problems caused by positional deviation. The bottom surface of the dam 4 is in contact with the bottom surface of the mounting groove 21, providing a stable support for the dam 4 and helping to prevent the dam 4 from deforming or shifting during the encapsulation process, thereby ensuring the stability of the encapsulation. At the same time, it also achieves an effective sealing effect, preventing solder from overflowing from the gap between the dam 4 and the cover plate 2, thereby improving the quality of the encapsulation.

[0038] The dam 4 is fixedly connected to the upper surface of the cover plate 2 by sintering or bonding. The sintering method involves melting and penetrating the dam 4 material into the surface of the cover plate 2, while the bonding method involves coating the cover plate 2 with a polymer adhesive layer and curing it. Regardless of whether the sintering or bonding method is used, the dam 4 is fixedly set on the cover plate 2 without any gaps between it and the upper surface of the cover plate 2, which makes the isolation effect of the dam 4 better and prevents the solder from overflowing from the dam 4.

[0039] The above embodiments are only for illustrating the technical concept and features of this utility model, and are intended to enable those skilled in the art to understand the content of this utility model and implement it accordingly. They should not be construed as limiting the scope of protection of this utility model. It is obvious to those skilled in the art that this utility model is not limited to the details of the above exemplary embodiments, and that it can be implemented in other specific forms without departing from the spirit or basic characteristics of this utility model. Therefore, the embodiments should be considered exemplary and non-limiting in all respects. The scope of this utility model is defined by the appended claims rather than the foregoing description, and therefore, all changes falling within the meaning and scope of the equivalents of the claims are intended to be included within this utility model.

Claims

1. A dam to prevent solder spillage, characterized in that, include: A substrate (1) has an extension portion (11) extending upward around its periphery. The extension portion (11) is arranged around the substrate and forms a cavity (12) inside it. A chip is soldered into the cavity (12). The cover plate (2) is welded to the extension (11) and has a square-shaped structure; Germanium window (3), the germanium window (3) is welded to the cover plate (2) along the outer edge contour of the germanium window (3); The dam (4) extends upward from the surface of the cover plate (2) body, and its inner boundary projection falls outside the outer edge of the germanium window (3). The inner wall of the dam (4) forms a continuous closed barrier surface (41) to prevent the solder from overflowing.

2. A dam for preventing solder overflow according to claim 1, characterized in that: The dam (4) is a protrusion on the upper surface of the cover plate (2), which is higher than the cover plate (2) and has no gap between its root and the upper surface of the cover plate (2).

3. A dam for preventing solder spillage according to claim 1, characterized in that: There is a certain distance between the two side walls adjacent to the dam (4) and the germanium window (3).

4. A dam for preventing solder overflow according to claim 1, characterized in that: The cover plate (2) has an installation groove (21) arranged around its outline on its upper surface. The dam (4) is arranged in the installation groove (21), and the bottom surface of the dam (4) is in contact with the bottom surface of the installation groove (21).

5. A dam for preventing solder overflow according to claim 1, characterized in that: The barrier surface (41) is an arc surface, or a plane perpendicular to the upper surface of the cover plate (2), or an inclined plane forming an angle with the upper surface of the cover plate (2).

6. A dam for preventing solder overflow according to claim 1, characterized in that: The dam (4) is fixedly connected to the upper surface of the cover plate (2) by sintering or bonding. The sintering method involves melting and penetrating the dam (4) material into the surface of the cover plate (2), while the bonding method involves coating the cover plate (2) with a polymer adhesive layer and curing it.

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