Packaging method and structure

Abstract

The invention provides a packaging method and structure, and the method comprises the following steps: providing a substrate and a housing, and covering the housing on the substrate to define a hollow cavity; a vacuumizing part is formed at the joint of the shell and the substrate, and the vacuumizing part is coated with a second welding material; gas in the hollow cavity is pumped out through a vacuumizing part; and heating the second welding material to melt the second welding material so as to block the vacuumizing part, wherein a vacuum cavity is defined by the shell and the substrate. The method is simple, the difficulty of the packaging method and the packaging cost are reduced, a packaging structure with low thermal stress, low deformation and high vacuum is conveniently formed through packaging, stable work of the micro-electromechanical sensor is ensured, the performance, the yield and the air tightness of a packaged product are improved, and the packaging cost and difficulty are reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of chip packaging, and in particular to a packaging method and structure. Background Art

[0002] MEMS micro-electromechanical sensors such as accelerometers and gyroscopes are susceptible to external changes such as stress, strain, moisture corrosion and air damping, which seriously affect the performance and function of the device itself. Therefore, in order to solve the above problems, the chips of such devices need to work in a vacuum cavity.

[0003] In the prior art, for chips that are flip-chip soldered on a substrate, a large area of ​​coating resin material is directly covered on the back of the chip to form a packaging structure. Although the formation of the cavity is achieved to a certain extent, the large area of ​​coating resin material directly covers the back of the chip, which will produce great thermal stress on the chip itself. At the same time, because the film is a resin material that is water-absorbent and not completely airtight, the chip cannot work in a vacuum state. Therefore, this structure cannot meet the packaging requirements of micro-electromechanical sensors such as accelerometers and gyroscopes.

[0004] To this end, one solution is to form a packaging cavity on the chip, open a vent hole on the packaging cavity, and use the existing wafer bonding technology for packaging. Then place the bonded assembly in a high temperature and high vacuum environment, and the gas in the microchamber is extracted through the reserved vent hole to make the pressure of the bonding chamber the same as the environment. Finally, other methods (such as hot pressing welding) are used to seal the reserved vent hole, so that the bonding chamber has a very high vacuum degree and good airtightness. For example, Druck uses glass tubes to vacuum package pressure sensors based on this principle. On the one hand, the glass chip bonding temperature is usually 500-620℃. Due to the high melting welding temperature, the chip in the package is baked at high temperature, which can easily cause thermal deformation of the chip and change the performance of the functional material, thereby affecting the mechanical and electrical properties of the device. On the other hand, opening holes in the packaging cavity is prone to problems such as poor sealing and cracks in the packaging cavity, resulting in a decrease in the performance, yield and airtightness of the packaged product, and increasing the packaging cost. Summary of the invention

[0005] In order to solve technical problems such as how to package to form a packaging environment with low thermal stress, low deformation and high vacuum, how to improve the performance, yield rate and air tightness of the packaged products, and how to reduce the packaging cost and simplify the packaging method, the present application provides a packaging method and structure.

[0006] In a first aspect, the present application provides a packaging method, comprising the following steps:

[0007] A substrate and a shell are provided, and the shell is covered on the substrate to define a hollow cavity; a vacuum part is formed at the connection between the shell and the substrate, wherein the vacuum part is coated with a second welding material; the gas in the hollow cavity is evacuated through the vacuum part; the second welding material is heated to melt it to seal the vacuum part, and the shell and the substrate define a vacuum cavity.

[0008] In a specific possible implementation scheme, a vacuum portion is formed at the connection between the outer shell and the substrate, including: setting a first welding material and a second welding material to the bottom of the outer shell, and / or, the top of the substrate, wherein the first welding material and the second welding material are polymerizable, and the melting point of the first welding material is lower than the melting point of the second welding material; heating the first welding material to melt it to form a protruding structure to fix the outer shell to the substrate, and forming a vacuum portion at the position coated with the second welding material.

[0009] In a specific possible implementation manner, the method further comprises: disposing a metal layer on the top of the substrate and / or the bottom of the housing; and disposing the first welding material and the second welding material on the metal layer.

[0010] In a specific possible implementation manner, the spatial volume of the melted second welding material is not less than the volume of the vacuum part.

[0011] In a specific embodiment, the first welding material and the second welding material include at least one of tin, copper, silver, bismuth, lead and nickel.

[0012] In a specific possible implementation manner, the method further comprises: electrically connecting the chip and / or the component to the pins of the substrate; and the chip and / or the component is disposed in the vacuum chamber.

[0013] The present application provides a packaging structure packaged according to any of the packaging methods described above, comprising: a substrate, on which chips and / or components are arranged; a shell, which is covered on the substrate and defines a hollow cavity with the substrate; a vacuum pumping part, which is located at the connection between the shell and the substrate to remove the gas in the central control cavity so that the shell and the substrate define a vacuum cavity.

[0014] In a specific possible implementation manner, the structure further includes: a welding part, wherein the welding part is arranged at the connection between the substrate and the shell.

[0015] In a specific possible implementation manner, the welding part includes a first welding part and a second welding part; wherein, the first welding part, the shell and the substrate define a vacuum part; and the second welding part is arranged in the vacuum part to seal the vacuum part.

[0016] In summary, the packaging method and structure provided by the present application include the following beneficial technical effects:

[0017] Solder materials with different melting points are coated on the contact surface of the shell and / or substrate. The temperature is first raised to a temperature that melts the first soldering material. The first soldering material melts and fixes the shell to the substrate. A vacuum part is formed at the position coated with the second soldering material. The hollow cavity defined by the shell and the substrate is vacuumed by the vacuum part. After the gas in the hollow cavity is completely evacuated, the temperature is raised to the melting point of the second soldering material. The second soldering material melts and seals the vacuum part to form a vacuum cavity. Based on the above packaging method, it is easy to package a packaging structure with low thermal stress, low deformation and high vacuum, which ensures the stable operation of micro-electromechanical sensors. Moreover, the vacuum part can be formed without opening holes, which avoids the cracks that are easy to occur due to opening holes in the package cavity, improves the yield rate of the packaging structure, and reduces the packaging cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a flow chart of the packaging method provided by the present invention;

[0019] Figure 2 is a front view of the packaging structure provided by the present invention;

[0020] Figure 3 is a top view of the packaging structure provided by the present invention;

[0021] Figure 4 is a side view of the packaging structure provided by the present invention (forming a vacuum pumping portion);

[0022] Figure 5 is a schematic structural diagram of the packaging structure provided by the present invention (the vacuum part is sealed by the second welding material);

[0023] Figure numerals: 1-housing; 2-substrate; 3-vacuum part; 4-welding part; 41-first welding part; 42-second welding part; 5-gold wire; 6-substrate pad; 7-chip; 8-vacuum chamber; 9-first gap; 10-second gap; 11-third gap. DETAILED DESCRIPTION

[0024] In order to make the objectives, technical solutions and advantages of the present application clearer, the implementation methods of the present application will be further described in detail below with reference to the accompanying drawings.

[0025] Embodiment 1

[0026] like Figure 1 As shown, this embodiment provides a packaging method, comprising the following steps:

[0027] Step S1, providing a substrate 2 and a housing 1, and covering the housing 1 on the substrate 2 to define a hollow cavity;

[0028] Step S2, forming a vacuum part 3 at the connection between the housing 1 and the substrate 2, wherein the vacuum part 3 is coated with a second welding material;

[0029] Step S3, removing the gas in the hollow cavity through the vacuum pumping part 3;

[0030] Step S4 , heating the second welding material to melt it to seal the vacuum part 3 , and the housing 1 and the substrate 2 define a vacuum chamber 8 .

[0031] The above packaging method is simple, and there is no need to place the bonded assembly sheet in a high temperature, high vacuum environment for vacuuming, which reduces the difficulty and cost of the packaging method, facilitates the packaging to form a packaging structure with low thermal stress, low deformation and high vacuum, and ensures the stable operation of the micro-electromechanical sensor. In addition, there is no need to form a vacuum part by opening a hole, which avoids the problem of cracks that are prone to occur when opening a hole in the package cavity, thereby improving the yield rate of the packaging structure.

[0032] In one embodiment, the step S1 further includes the following steps:

[0033] Step S11, electrically connecting the chip 7 and / or the components to the pins of the substrate 2; the chip 7 and / or the components are arranged in the vacuum chamber 8;

[0034] Step S12, providing a metal layer on the top of the substrate 2 and / or the bottom of the housing 1;

[0035] Step S13, placing the first welding material and the second welding material on the metal layer;

[0036] Step S14 : The metal layer disposed on the bottom of the housing 1 is correspondingly bonded to the metal layer disposed on the top of the substrate 2 , so that the housing 1 and the substrate 2 define a hollow cavity.

[0037] It should be understood that the purpose of providing a metal layer on the top of the substrate 2 and / or the bottom of the shell 1 in this embodiment is to ensure that the welding material provided at the connection between the substrate 2 and the shell 1 is melted to form a welding piece 4 that can effectively fix the shell 1 and the substrate 2. In actual application scenarios, when the shell 1 is made of metal material, and further, when the material of the shell 1 can ensure that the welding material forms a welding piece 4 that can achieve a fixed connection between the shell 1 and the substrate 2, it is not necessary to provide a metal layer on the bottom of the shell 1, thereby simplifying the method flow and reducing the production cost.

[0038] In addition, it should be understood that the actual process of the packaging method is not limited in this embodiment; for example, those skilled in the art may first perform the above step S12 and then perform the above step S11 according to actual conditions.

[0039] Step S2, forming a vacuum part 3 at the connection between the housing 1 and the substrate 2, wherein the vacuum part 3 is coated with a second welding material;

[0040] In one embodiment, the step S2 further includes the following steps:

[0041] Step S21, setting a first welding material and a second welding material to the bottom of the housing 1 and / or the top of the substrate 2, wherein the first welding material and the second welding material are polymerizable, and the melting point of the first welding material is lower than the melting point of the second welding material;

[0042] Step S22, heating the first welding material to melt it to form a protruding structure to fix the housing 1 to the substrate 2, and forming a vacuum portion 3 at a position coated with the second welding material.

[0043] Specifically, since the welding materials (i.e., the first welding material and the second welding material) are polymerizable, after the welding materials are melted, their surfaces will bulge under the action of surface tension to form a bulge structure, thereby increasing the distance between the shell 1 and the substrate 2 and firmly welding the shell 1 and the substrate 2 together.

[0044] Specifically, the shell 1 and the substrate 2 coated with the first welding material and the second welding material are placed in a heating device, and the temperature is firstly raised to the melting point temperature of the first welding material to melt the first welding material, and the heating device continues to heat to the melting point temperature of the second welding material to melt the second welding material. The method is simple and easy to operate.

[0045] In one embodiment, the distance between the two intersection points between the second welding material and the first welding material is not less than the first preset value, so as to prevent the first welding material from covering the second welding material with a large area when the first welding material is heated to melt, resulting in failure to form a vacuum portion 3 at the location coated with the second welding material. It should be understood that, because the first welding material and the second welding material themselves have the characteristics of polymerization, when the distance between the two intersection points between the coated first welding material and the second welding material is not less than the first preset value, when the first welding material is heated to melt, the first welding material will polymerize with its homogeneous material due to its polymerization, and will not completely cover the second welding material due to its fluidity, so that the vacuum portion 3 can be formed at the location coated with the second welding material.

[0046] In one embodiment, a height difference is set between the first welding material and the second welding material, that is, the coating thickness of the second welding material is greater than the coating thickness of the first welding material; to ensure that when the first welding material is heated to melt, the first welding material is effectively blocked from flowing to the top of the second welding material, so that a vacuum portion 3 is formed where the second welding material is coated. It should be understood that the present application does not limit the size of the height difference set between the first welding material and the second welding material. Those skilled in the art can reasonably set it according to various factors such as the actual packaging scenario and the characteristics of the welding materials. It is only necessary to ensure that the first welding material will not flow to the top of the second welding material when the first welding material is melted.

[0047] In one embodiment, the method also includes: providing a metal shrapnel (not shown in the figure), fixing one end of the metal shrapnel on the top of the substrate 2 and / or the bottom of the shell 1; when the first welding material is not melted, the metal shrapnel is in an initial position; when the first welding material is melted, the metal shrapnel is in a preset position; wherein, the metal shrapnel is in the initial position includes: the metal shrapnel is attached to the shell 1, or, the substrate 2; the metal shrapnel is in the preset position includes: the other end of the metal shrapnel is abutted against the substrate 2, or, the shell 1; when the metal shrapnel is in the preset position, the distance between the substrate 2 and the shell 1 is not greater than the height of the protruding structure formed by the first welding material.

[0048] Specifically, a metal shrapnel is provided, one end of the metal shrapnel is fixed on the substrate 2, and the metal shrapnel is welded by a first welding material to be in an initial state, that is, the metal shrapnel is attached to the top of the substrate 2; the first welding material is heated to melt it to form a convex structure, and the convex structure lifts the metal shrapnel originally attached to the top of the substrate 2 so that the other end of the metal shrapnel abuts against the bottom of the shell 1, and the metal shrapnel acts as a retaining wall to prevent the first welding material from flowing to the area coated with the second welding material due to its fluidity when it melts. Furthermore, the side section of the metal shrapnel is arc-shaped, and when the metal shrapnel is attached to the top of the substrate 2, the curvature of the metal shrapnel bulges toward the shell 1.

[0049] In one embodiment, the difference in melting point between the first welding material and the second welding material is not more than 40° C. This prevents the occurrence of a sudden change in the characteristics of another welding material due to excessive temperature during the heating process of one welding material (the first welding material or the second welding material).

[0050] It should be understood that when the first welding material or the second welding material is an alloy material, the eutectic point of the first welding material or the second welding material (the temperature point at which the first welding material or the second welding material melts) is the melting point described in this application; when the first welding material or the second welding material is a non-alloy material such as tin, nickel, etc., the temperature point at which the first welding material or the second welding material melts is the melting point.

[0051] In one embodiment, the spatial volume of the melted second welding material is not less than the volume of the vacuum part 3, so as to achieve the beneficial effect of completely sealing the vacuum part 3 and ensuring the airtightness of the vacuum chamber 8.

[0052] In one embodiment, the first welding material and the second welding material include at least one of tin, copper, silver, bismuth, lead, and nickel.

[0053] In one embodiment, the method further includes: providing a fixed connection structure on the substrate 2 based on the bottom structural shape of the shell 1 to limit the shell 1. When the top surface of the substrate 2 and the bottom surface of the shell 1 are both horizontal planes, when the welding material coated at the connection between the shell 1 and the substrate 2 is heated, the position of the welding material may shift after polymerization, thereby causing the shell 1 and the substrate 2 to shift relative to each other. Therefore, providing a fixed connection structure at the top of the substrate 2 corresponding to the bottom structural shape of the shell 1 helps to ensure the relative stability of the shell 1 and the substrate 2.

[0054] Preferably, a corresponding groove can be provided on the substrate 2 based on the bottom structure of the shell 1 to ensure the relative stability of the shell 1 and the substrate 2 during the heating of the welding material. It should be understood that the present application does not limit the specific structural form of the fixed structure, and it is only necessary to ensure that the relative position relationship between the shell 1 and the substrate 2 remains unchanged when the welding material is heated. For example, a person skilled in the art can provide a groove at the bottom of the shell 1, and form a convex structure on the substrate 2 that is adapted to connect with the groove, so that the shell 1 and the substrate 2 are fixedly connected.

[0055] Furthermore, when a groove is provided on the substrate 2 corresponding to the bottom structure of the shell 1, the soldering material can be coated only on the concave part of the groove; the beneficial effect is that, without affecting the stability of the connection between the shell 1 and the substrate 2, the actual structure of the groove can also effectively prevent the soldering material from flowing to the chip bonding area due to its fluidity, thereby preventing contamination and damage to the chip.

[0056] Preferably, the height of the fixed connection structure is not lower than the height of the protruding structure formed by melting of the first welding material.

[0057] In one specific embodiment, the second welding material is heated to melt to seal the vacuum part 3, and after the shell 1 and the substrate 2 define a vacuum cavity 8, the method further includes: plastic sealing the shell 1 onto the substrate 2; on the one hand, the secondary sealing of the vacuum part 3 is performed to ensure the airtightness of the vacuum cavity 8, and on the other hand, the stability of the entire packaging structure is improved.

[0058] Embodiment 2

[0059] like Figures 2 to 5 As shown, this embodiment provides a packaging structure obtained by packaging based on the packaging method described in Embodiment 1, and the packaging structure includes:

[0060] A substrate 2, on which a chip 7 and / or components are arranged;

[0061] A housing 1, wherein the housing 1 is disposed on the substrate 2 and defines a hollow cavity with the substrate 2;

[0062] The vacuum pumping part 3 is located at the connection between the outer shell 1 and the substrate 2 and is used to evacuate the gas in the central control cavity so that the outer shell 1 and the substrate 2 define a vacuum cavity 8 .

[0063] The above packaging structure forms a packaging environment with low thermal stress, low deformation and high vacuum, ensuring the high sensitivity, high precision and long-term stable operation of the micro-electromechanical sensor chip, and the packaging difficulty and cost are relatively low.

[0064] In one embodiment, the structure further includes: a welding member 4, which is arranged at the connection between the substrate 2 and the shell 1. The welding member 4 includes a first welding member 41 and a first welding member 42; wherein the first welding member 41, the shell 1 and the substrate 2 define a hollow cavity and a vacuum part 3; the second welding member 42 is arranged in the vacuum part 3 to seal the vacuum part 3. wherein the first welding member 41 is formed by the first welding material being melted and solidified; the second welding material 42 is formed by the second welding material being melted and fixed.

[0065] In one embodiment, a blocking member is disposed between the first welding member 41 and the second welding member 42 to form the vacuum portion 3 .

[0066] Preferably, the blocking member comprises a metal spring, which is in an initial state when the first welding member 41 is not formed; and is in a target state after the first welding member 41 is formed. The initial state of the metal spring is that the metal spring is attached to the top of the substrate 2; the target state of the metal spring is that one end of the metal spring is fixed to the top of the substrate 2, and the other end is abutted against the bottom of the housing 1, and is located at the intersection of the first welding member 41 and the second welding member 42.

[0067] In one embodiment, a metal layer is provided at the bottom of the housing 1 and the top of the substrate 2, and a welding piece is located between the metal layer of the substrate 2 and the metal layer of the housing 1, so as to weld the housing 1 to the top of the substrate 2. It should be understood that when the housing 1 is made of metal material or the housing 1 can be directly fixedly connected to the substrate 2 by a welding piece, it is not necessary to provide a metal layer on the housing 1; the same is true for the substrate 2.

[0068] Preferably, the first welding member 41 is formed by heating and melting the first welding material and then solidifying it.

[0069] Preferably, the first welding member 42 is formed by heating and melting the second welding material and then solidifying it.

[0070] Preferably, the first welding part 41 and the second welding part 42 are arranged at intervals between the substrate 2 and the outer shell 1, and the first welding part 41 is arranged at the contact end of the substrate 2 and the outer shell 1 to form a plurality of vacuum pumping parts 3. The hollow cavity is evacuated by the plurality of vacuum pumping parts 3, which reduces the vacuum pumping time and improves the vacuum pumping efficiency.

[0071] Preferably, a chip 7 is provided in the vacuum chamber 8 , and the chip 7 is connected to the substrate 2 by flip-chip connection or wire bonding, and a first gap 9 is defined between the other end surface of the chip 7 and the housing 1 .

[0072] Preferably, there is a second gap 10 between one side of the chip 7 and the housing 1, and a third gap 11 between the other side of the chip 7 and the housing 1; on the one hand, the flowable soldering material after heating is prevented from contaminating the chip 7 due to its fluidity.

[0073] The material of the substrate 2 is preferably ceramic material, which further reduces the thermal stress on the chip package.

[0074] The material of the housing 1 is preferably metal material, which reduces the cost of packaging and the cost of the packaging structure.

[0075] Preferably, a plurality of substrate pads 6 are provided on the substrate 2 , and the chip 7 is connected to the substrate pads 6 via gold wires 5 .

[0076] Embodiment 3

[0077] Based on the packaging method described in the first embodiment, this embodiment is specifically described, and specifically includes the following steps:

[0078] A metal shell 1 and a substrate 2 are provided, wherein a SnPb alloy material and a Sn-Cu-Ag alloy material are coated at a contact point between the metal shell 1 and the substrate 2, and the SnPb alloy material is coated between every two adjacent Sn-Cu-Ag alloy materials;

[0079] The metal shell 1 coated with SnPb alloy material and Sn-Cu-Ag alloy material and the substrate 2 are placed in a heating device;

[0080] The heating device heats the SnPb alloy material to a melting point temperature of 183° C. The SnPb alloy material is heated and melted so that the metal shell 1 and the ceramic substrate 2 are connected to form a hollow cavity. Since the SnPb alloy material has polymerization after being heated, the distance between the metal shell 1 and the substrate 2 at the position of the SnPb alloy material is increased, so that a gap appears between the metal shell 1 and the substrate 2 at the position of the Sn-Cu-Ag alloy material to form a vacuum portion 3;

[0081] The hollow cavity is evacuated by the evacuation part 3;

[0082] The heating device continues to heat the Sn-Cu-Ag alloy material to a melting point of 211° C., and the Sn-Cu-Ag alloy material is heated and melted. Since the Sn-Cu-Ag alloy material is heated and melted, the metal shell 1 and the ceramic substrate 2 seal the vacuuming part 3 at the position of the Sn-Cu-Ag alloy material.

[0083] The packaging method and structure provided in this embodiment not only form a packaging environment with low thermal stress, low deformation and high vacuum, thereby ensuring the high sensitivity, high precision and long-term stable operation of the micro-electromechanical sensor chip 7, and reducing the packaging difficulty and cost as much as possible, but also improve the performance, yield rate and airtightness of the packaged product.

[0084] Embodiment 4

[0085] Based on the packaging method described in the first embodiment, this embodiment is specifically described, and specifically includes the following steps:

[0086] The contact portion between the shell 1 and the substrate 2 is coated with an In metal material and a Sn35Pb65 alloy material, the In metal material and the Sn35Pb65 alloy material are coated at intervals between the substrate 2 and the shell 1, and the In metal material is coated at the contact end portion between the substrate 2 and the shell 1;

[0087] Place the housing 1 and the substrate 2 coated with the In metal material and the Sn35Pb65 alloy material in a heating device;

[0088] The heating device heats the I n metal material to a melting point temperature of 156.61° C., and after the I n metal material is heated and melted, the shell 1 and the substrate 2 are connected to form a hollow cavity. Due to the polymerization of the I n metal material after being heated, the distance between the shell 1 and the substrate 2 at the position of the I n metal material is increased, so that a gap appears between the shell 1 and the substrate 2 at the position of the Sn35Pb65 alloy material to form a plurality of vacuum parts 3;

[0089] The hollow cavity is evacuated by using a plurality of evacuation parts 3;

[0090] The heating device continues to heat up to the melting point of the Sn35Pb65 alloy material, 198° C., and the second welding material melts. After the second welding material melts, its surface will bulge under the action of surface tension to form a blocking structure, thereby sealing the vacuum part 3.

[0091] The packaging method and structure provided in this embodiment not only form a packaging environment with low thermal stress, low deformation and high vacuum, thereby ensuring the high sensitivity, high precision and long-term stable operation of the micro-electromechanical sensor chip, and reducing the packaging difficulty and cost as much as possible, but also improve the performance, yield rate and air tightness of the packaged product.

[0092] The above is a detailed introduction to a packaging method and structure provided by the present application. The principles and implementation methods of the present application are described in detail using specific examples. The description of the above embodiments is only used to help understand the method and core ideas of the present application. At the same time, for those skilled in the art, according to the ideas of the present application, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as limiting the present application.

Claims

1. A packaging method, It is characterized in that The following steps are involved: Providing a substrate and a housing, and covering the housing on the substrate to define a hollow cavity; forming a vacuum part at the connection between the housing and the substrate, wherein the vacuum part is coated with a second welding material; Extracting gas from the hollow cavity through a vacuum extraction part; The second welding material is heated to melt the second welding material so as to seal the vacuum part. The housing and the substrate define a vacuum cavity.

2. The packaging method according to claim 1, It is characterized in that A vacuum pumping portion is formed at the connection between the housing and the substrate, comprising: Disposing a first welding material and a second welding material to the bottom of the housing and / or the top of the substrate, wherein the first welding material and the second welding material are polymerizable, and the melting point of the first welding material is lower than the melting point of the second welding material; The first welding material is heated to melt and form a protruding structure to fix the housing to the substrate, and a vacuum portion is formed at a location coated with the second welding material.

3. The packaging method according to claim 2, It is characterized in that The difference in melting point between the first welding material and the second welding material does not exceed 40°C.

4. The packaging method according to claim 3, It is characterized in that The method further comprises: Disposing a metal layer on the top of the substrate and / or the bottom of the housing; The first welding material and the second welding material are disposed on the metal layer.

5. The packaging method according to claim 2, It is characterized in that The spatial volume of the melted second welding material is not less than the volume of the vacuum part.

6. The packaging method according to any one of claims 1 to 5, It is characterized in that The first welding material and the second welding material include at least one of tin, copper, silver, bismuth, lead and nickel.

7. The packaging method according to claim 6, It is characterized in that The method further includes: electrically connecting the chip and / or the component to the pins of the substrate; and the chip and / or the component is arranged in the vacuum chamber.

8. A packaging structure, It is characterized in that The packaging structure is obtained by packaging according to the packaging method according to any one of claims 1 to 7, and comprises: A substrate, on which chips and / or components are arranged; A housing, the housing is disposed on the substrate and defines a hollow cavity with the substrate; A vacuum pumping part is located at the connection between the shell and the substrate, and is used to pump out the gas in the central control cavity so that the shell and the substrate define a vacuum cavity.

9. The packaging structure according to claim 8, It is characterized in that The structure also includes: A welding piece is arranged at the connection between the substrate and the shell.

10. The packaging structure according to claim 9, It is characterized in that The welding part includes a first welding part and a second welding part; wherein the first welding part, the shell and the substrate form the vacuum pumping part; and the second welding part is arranged in the vacuum pumping part to seal the vacuum pumping part.

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