Atomic clock system and vacuum packaging method

Abstract

This application provides an atomic clock system and a vacuum packaging method. The atomic clock system includes a housing, a connecting component, and an optical path structure. Both the connecting component and the optical path structure are located in a sealed cavity within the housing. The inner wall of the cavity forming the housing has a first stepped portion, and the optical path structure is fixedly connected to the first stepped portion via the connecting component. A gap exists between the optical path structure and the inner wall. The atomic clock system provided in this application reduces the power consumption of the CPT atomic clock.

Description

Technical Field

[0001] This application relates to the field of atomic clock technology, and in particular to an atomic clock system and a vacuum packaging method. Background Technology

[0002] Coherent Population Trapping (CPT) atomic clocks are a new type of atomic clock that utilizes the principle of coherent population trapping of atoms. Since they no longer require microwave resonant cavities, they can be truly miniaturized.

[0003] The CPT atomic clock consists of an optical path structure and a housing. The optical path structure, including a laser tube and atomic gas chambers, is housed within the housing. During startup, the laser tube and atomic gas chambers require heating and maintenance at high operating temperatures. Currently, the optical path structure is typically mounted on the inner surface of the housing. This allows the optical path structure to exchange heat with the external environment through the housing, leading to heat loss and resulting in high power consumption for the CPT atomic clock. Summary of the Invention

[0004] This application provides an atomic clock system and a vacuum packaging method that reduces the power consumption of a CPT atomic clock.

[0005] To achieve the above objectives, embodiments of this application provide an atomic clock system, including a housing, connecting components, and an optical path structure;

[0006] Both the connecting component and the optical path structure are located in a sealed cavity within the housing. The inner wall of the housing forming the cavity is provided with a first step portion, and the optical path structure is fixedly connected to the first step portion through the connecting component.

[0007] There is a gap between the optical path structure and the inner wall.

[0008] Optionally, the housing includes a base, a cap, and a solder ring;

[0009] The base is provided with a first step and a second step, the second step and the cap are connected in a sealed manner by the solder ring to form the cavity, and the inner wall of the cap is coated with a getter.

[0010] The optical path structure has gaps between itself and the inner wall of the base and the inner wall of the cap.

[0011] Optionally, the connection assembly includes a first connector and a second connector that are interconnected.

[0012] The first connector is also connected to the first stepped portion and the optical path structure respectively;

[0013] The second connector is also connected to the optical path structure;

[0014] The optical path structure includes a first surface that contacts the first connector and a second surface that contacts the second connector. The contact area between the first connector and the optical path structure is smaller than the area of ​​the first surface, and the contact area between the second connector and the optical path structure is smaller than the area of ​​the second surface.

[0015] Optionally, the first connector includes a first bracket arranged in a cross shape and a second bracket arranged in a ring shape, and the second connector includes a side plate and a top plate disposed on a first side of the side plate;

[0016] The second bracket is fixedly connected to the first bracket, and the second side of the side plate is fixedly connected to the second bracket to form a space, in which the optical path structure is located;

[0017] The first surface of the optical path structure is fixedly connected to the first bracket, and the second surface of the optical path structure is fixedly connected to the top plate;

[0018] The second bracket is also fixedly connected to the first stepped portion;

[0019] The first side and the second side of the side plate are opposite sides.

[0020] Optionally, the outer surface of the base is provided with lead electrodes for electrical connection with an external circuit, and the first stepped portion is provided with a connecting layer, which is electrically connected to the lead electrodes;

[0021] The optical path structure is electrically connected to the connection layer through the connection component.

[0022] This application provides a vacuum encapsulation method for vacuum encapsulating an atomic clock system as described in the first aspect, the method comprising:

[0023] Assemble the connecting components, optical path structure, and base to obtain the assembly structure;

[0024] The solder ring is heated to the reflow temperature, the cap is heated to the activation temperature, and the solder ring and the cap are both at the reflow temperature at the same target time.

[0025] At the target time, the base and the cap are connected by the solder ring in a vacuum environment;

[0026] Wherein, the reflow temperature is the reflow temperature of the solder ring, and the activation temperature is the activation temperature of the getter on the inner wall of the cap.

[0027] Optionally, heating the solder ring to the reflow temperature, heating the cap to the activation temperature, and ensuring that the solder ring and the cap are both at the same target temperature at the same time includes:

[0028] The assembly structure is placed in the first temperature zone, and the solder ring is placed in the second step of the base;

[0029] Place the cap in the second temperature zone;

[0030] The solder ring is heated to the reflow temperature by heating the first temperature zone, and the cap is heated to the activation temperature by heating the second temperature zone, so that the solder ring and the cap are both at the reflow temperature at the same target time;

[0031] The first temperature zone and the second temperature zone are vacuum zones, representing different temperature control areas.

[0032] Optionally, the control method that ensures the solder ring and the cap are both at the same target temperature at the reflow temperature includes at least one of the following:

[0033] By controlling the timing of temperature changes in the first temperature zone and the second temperature zone, the solder ring and the cap are both at the same target temperature at the reflow temperature.

[0034] By controlling the temperature change rate of the first temperature zone and the temperature change rate of the second temperature zone, the solder ring and the cap are both at the reflow temperature at the same target time.

[0035] The time of temperature change includes at least one of the time of heating up and the time of cooling down;

[0036] The rate of temperature change includes at least one of the heating rate and the cooling rate.

[0037] Optionally, the activation temperature is greater than the reflow temperature, the first cooling duration of the second temperature zone is greater than the first heating duration of the first temperature zone, and the step of heating the solder ring to the reflow temperature by heating the first temperature zone, heating the cap to the activation temperature by heating the second temperature zone, and ensuring that the solder ring and the cap are both at the same target temperature at the same time, includes:

[0038] After heating the cap to the activation temperature to activate the getter, the cap is cooled down.

[0039] From the moment the cap begins to be heated, after a first preset time, the solder ring is heated so that both the solder ring and the cap are at the reflow temperature at the target time;

[0040] Wherein, the first cooling time is the time required for the second temperature zone to drop from the activation temperature to the reflux temperature;

[0041] The first heating time is the time required for the first temperature zone to rise from the degassing temperature to the reflux temperature.

[0042] Optionally, the activation temperature is greater than the reflow temperature, the second cooling time of the second temperature zone is less than the second heating time of the first temperature zone, and the step of heating the solder ring to the reflow temperature by heating the first temperature zone, heating the cap to the activation temperature by heating the second temperature zone, and ensuring that the solder ring and the cap are both at the reflow temperature at the same target time includes:

[0043] The solder ring is heated;

[0044] From the moment the solder ring begins to be heated, after a second preset time, the cap is heated to the activation temperature. After the cap is heated to the activation temperature to activate the getter, the cap is cooled down so that the solder ring and the cap are both at the reflow temperature at the target time.

[0045] Wherein, the second cooling time is the time required for the second temperature zone to drop from the activation temperature to the reflux temperature;

[0046] The second heating time is the time required for the first temperature zone to rise from the degassing temperature to the reflux temperature.

[0047] Optionally, the activation temperature is lower than the reflow temperature, and the step of heating the solder ring to the reflow temperature by heating the first temperature zone, heating the cap to the activation temperature by heating the second temperature zone, and ensuring that the solder ring and the cap are both at the reflow temperature at the same target time includes:

[0048] After activating the getter by heating the cap to the activation temperature, the cap is further heated.

[0049] After a third preset time period following the start of heating the cap, the solder ring is heated so that both the solder ring and the cap are at the reflow temperature at the target time.

[0050] Wherein, the third heating time is the time required for the second temperature zone to rise from the activation temperature to the reflux temperature;

[0051] The fourth heating time is the time required for the first temperature zone to rise from the degassing temperature to the reflux temperature.

[0052] Optionally, the activation temperature is lower than the reflow temperature, the fifth heating time of the second temperature zone is shorter than the sixth heating time of the first temperature zone, and the step of heating the solder ring to the reflow temperature by heating the first temperature zone, heating the cap to the activation temperature by heating the second temperature zone, and ensuring that the solder ring and the cap are both at the reflow temperature at the same target time includes:

[0053] The solder ring is heated;

[0054] After a fourth preset time period following the start of heating of the solder ring, the cap is heated, and after the cap is heated to the activation temperature to activate the getter, the cap is continued to be heated so that the solder ring and the cap are both at the reflow temperature at the target time.

[0055] Wherein, the fifth heating time is the time required for the second temperature zone to rise from the activation temperature to the reflux temperature;

[0056] The sixth heating time is the time required for the first temperature zone to rise from the degassing temperature to the reflux temperature.

[0057] Optionally, the activation temperature is lower than the reflow temperature, and the step of heating the solder ring to the reflow temperature, heating the cap to the activation temperature, and ensuring that both the solder ring and the cap are at the reflow temperature at a target time includes:

[0058] The assembly structure is placed in a first temperature zone, and the assembly structure is heated by heating the first temperature zone to raise the temperature, and the assembly structure is brought to the reflow temperature at the target time.

[0059] The solder ring is placed on the opening of the cap, and the solder ring and the cap are placed in the second temperature zone. The second temperature zone is heated so that the solder ring and the cap are both at the reflow temperature at the target time.

[0060] The first temperature zone and the second temperature zone are vacuum zones, representing different temperature control areas.

[0061] In this embodiment, the atomic clock system includes a housing, a connecting component, and an optical path structure. Both the connecting component and the optical path structure are located within a sealed cavity inside the housing. The optical path structure is fixed to the housing via a first step on the inner wall and the connecting component, creating a gap between the optical path structure and the inner wall. This prevents the optical path structure from being directly attached to the inner wall of the housing, thereby reducing heat exchange between the optical path structure and the housing, and consequently reducing heat loss and power consumption of the atomic clock system (CPT atomic clock).

[0062] Furthermore, in this embodiment, by heating the solder ring to the reflow temperature and the cap to the activation temperature, and ensuring that the solder ring and the cap are both at the same target reflow temperature, the base and the cap are connected by the solder ring in a vacuum environment at the target time, which makes the entire vacuum packaging process simpler and more reliable. Attached Figure Description

[0063] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings are described below. Obviously, the following drawings are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the listed drawings without creative effort.

[0064] Figure 1 This is one of the structural schematic diagrams of the atomic clock system provided in the embodiments of this application;

[0065] Figure 2 This is the second schematic diagram of the atomic clock system provided in the embodiments of this application;

[0066] Figure 3 This is a schematic diagram of the cap structure in the atomic clock system provided in this application embodiment;

[0067] Figure 4 This is a schematic diagram of the optical path structure and the first connector in the atomic clock system provided in this application embodiment;

[0068] Figure 5 This is a schematic diagram of the structure of the first connector, the optical path structure, and the second connector in the atomic clock system provided in the embodiments of this application;

[0069] Figure 6 This is a schematic diagram of the structure of the first connector, optical path structure, second connector, and base in the atomic clock system provided in the embodiments of this application;

[0070] Figure 7 This is a schematic flowchart of the vacuum sealing method provided in the embodiments of this application;

[0071] Figure 8 This is a schematic diagram of the vacuum sealing device provided in the embodiments of this application. Detailed Implementation

[0072] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0073] See Figure 1 and Figure 2 This application provides an atomic clock system, including a housing 10, a connecting component 30, and an optical path structure 20.

[0074] Both the connecting component 30 and the optical path structure 20 are located in a sealed cavity inside the housing 10. The inner wall of the housing 10 forming the cavity is provided with a first step portion 111. The optical path structure 20 is fixedly connected to the first step portion 111 through the connecting component 30.

[0075] In a specific implementation, the sealed cavity inside the housing 10 is in a vacuum state, and the first stepped portion 111 can be as follows: Figure 2 The square ring shape shown can also be other shapes. The connecting component 30 is fixedly connected to the optical path structure 20 and the first step portion 111 respectively, so that there is a gap between the optical path structure 20 and the inner wall of the cavity formed by the housing 10. In this way, the optical path structure 20 is not directly attached to the inner wall of the housing 10, thereby reducing the heat exchange between the optical path structure 20 and the housing 10, that is, reducing the heat exchange between the optical path structure 20 and the outside world, reducing heat loss, and thus reducing the power consumption of the atomic clock system (CPT atomic clock).

[0076] Optionally, see Figure 2 The housing 10 includes a base 11 and a cap 12. The base 11 can be a lead chip carrier (LCC) base 11, and the cap 12 can be made of ceramic. The base 11 has a first step portion 111 and a second step portion 112, which are hermetically connected to the cap 12 to form a cavity. There are gaps between the optical path structure 20 and the inner walls of both the base 11 and the cap 12. In this embodiment, by including the base 11 and the cap 12 in the housing 10, vacuum packaging can be facilitated.

[0077] Alternatively, in order to make the connection between the second step portion 112 and the cap 12 more secure, this application also provides the following three embodiments.

[0078] In Embodiment 1, the surface of the second step portion 112 and the opening surface of the cap 12 are provided with a gold-plated layer, that is, a layer of metal, including but not limited to gold and copper, is plated on the surface of the second step portion 112 and the opening surface of the cap 12. The second step portion 112 is fixedly connected to the cap 12 by the two gold-plated layers.

[0079] In the second embodiment, the housing 10 also includes a solder ring 13, and the second step portion 112 is fixedly connected to the cap 12 via the solder ring 13.

[0080] In embodiment three, the surface of the second step portion 112 and the opening surface of the cap 12 are provided with gold plating layers. The housing 10 also includes a solder ring 13. The material of the gold plating layer and the material of the solder ring 13 are compatible, that is, the material of the gold plating layer and the material of the solder ring 13 have good adhesion. The second step portion 112 is fixedly connected by the two gold plating layers, the solder ring 13 and the cap 12.

[0081] Optionally, see Figure 3 The inner wall of the cap 12 is coated with a getter. In practice, the getter can be a non-evaporable getter. By coating the inner wall of the cap 12 with a getter, residual gases slowly released from inside the atomic clock system after vacuum assembly and gases slowly leaking from the outside can be absorbed, thereby improving the vacuum level of the atomic clock system and extending its service life.

[0082] Optionally, see Figure 2 , Figure 4 and Figure 5 The connecting component 30 includes a first connector 31 and a second connector 32 that are connected to each other. The first connector 31 is also connected to the first step portion 111 and the optical path structure 20, respectively, and the second connector 32 is also connected to the optical path structure 20.

[0083] The optical path structure 20 includes a first surface that contacts the first connector 31 and a second surface that contacts the second connector 32. The contact area between the first connector 31 and the optical path structure 20 is smaller than the area of ​​the first surface, and the contact area between the second connector 32 and the optical path structure 20 is smaller than the area of ​​the second surface.

[0084] In a specific implementation, the shape of the optical path structure 20 can be a cuboid, and both the first connector 31 and the second connector 32 can be hollow structures, so that the contact area between the first connector 31 and the optical path structure 20 is smaller than the area of ​​the first surface, and the contact area between the second connector 32 and the optical path structure 20 is smaller than the area of ​​the second surface.

[0085] In this embodiment of the application, by making the contact area between the first connector 31 and the optical path structure 20 smaller than the area of ​​the first surface, and the contact area between the second connector 32 and the optical path structure 20 smaller than the area of ​​the second surface, the heat exchange between the optical path structure 20 and the housing 10 can be further reduced, that is, the heat exchange between the optical path structure 20 and the outside world is reduced, the heat loss is reduced, and the power consumption of the atomic clock system (CPT atomic clock) is reduced.

[0086] Optionally, see Figure 2 , Figure 4 and Figure 5The first connecting member 31 includes a first bracket arranged in a cross shape and a second bracket arranged in a ring shape. The second connecting member 32 includes a side plate and a top plate disposed on the first side of the side plate. The second bracket is fixedly connected to the first bracket, and the second side of the side plate is fixedly connected to the second bracket to form a space in which the optical path structure 20 is located. The first surface of the optical path structure 20 is fixedly connected to the first bracket, and the second surface of the optical path structure 20 is fixedly connected to the top plate. The second bracket is also fixedly connected to the first step portion 111. The first side and the second side of the side plate are opposite sides.

[0087] In practice, the first support can be made of crystalline silicon or ceramic, while the second support can be made of a material with excellent mechanical and thermal insulation properties, such as polyimide film. The side panels can be made of metal or ceramic, and the top panel can be made of a material with excellent mechanical and thermal insulation properties, such as polyimide film.

[0088] The top plate can also be composed of interconnected cross-shaped supports and ring-shaped supports.

[0089] In an optional embodiment of this application, the first support may also be arranged in a grid or triangular pattern. Similarly, the top plate may also be composed of supports arranged in a grid / triangular pattern or in a ring pattern.

[0090] In this embodiment, the first connector 31 includes a first bracket arranged in a cross shape and a second bracket arranged in a ring shape. The second connector 32 includes a side plate and a top plate disposed on a first side of the side plate. The first surface of the optical path structure 20 is fixedly connected to the first bracket, and the second surface of the optical path structure 20 is fixedly connected to the top plate. This reduces heat loss in the optical path structure 20, achieves vibration isolation, and improves the vibration and shock resistance of the optical path structure 20.

[0091] Optionally, see Figure 2 and Figure 6 The outer surface of the base 11 is provided with lead electrodes 113 for electrical connection with external circuits. The first step portion 111 is provided with a connecting layer 1111. The connecting layer 1111 is electrically connected to the lead electrodes 113. The optical path structure 20 is electrically connected to the connecting layer 1111 through the connecting component 30.

[0092] In a specific implementation, the first step portion 111 may be provided with multiple connection layers 1111, and the connection layers 1111 may be gold pads. The connection component 30 may be provided with gold pads 311 and solder corresponding to the connection layers 1111, so that the optical path structure 20 is electrically connected to the connection layer 1111 through the connection component 30, thereby connecting the optical path structure 20 to the external circuit through the lead electrode 113.

[0093] For example, in the case where the connecting component 30 includes a first connector 31 and a second connector 32, the first connector 31 includes a first bracket arranged in a cross shape and a second bracket arranged in a ring shape, and the second connector 32 includes a side plate and a top plate disposed on the first side of the side plate, multiple pairs of gold pads 311 and solder can be fabricated at the orthogonal projection position of the corresponding connecting layer 1111 on the upper and lower surfaces of the second bracket using electron beam evaporation (or sputtering process) and electroplating processes. Each pair of gold pads 311 on the upper and lower surfaces of the second bracket is electrically connected. If the material of the second bracket is a non-insulating material, insulation treatment should be performed between the second bracket and the gold pads 311. The optical path structure 20 is connected to the gold pads 311 on the surface of the second bracket via wires. The wires can be fabricated by means of gold wire bonding or the like.

[0094] In this embodiment of the application, the above-mentioned settings can realize the electrical connection between the external circuit and the optical path structure 20, and there is no need to open holes in the housing 10 to lead out wires, so that the cavity inside the housing 10 can be completely sealed in a vacuum state.

[0095] See Figure 7 This application also provides a vacuum packaging method for vacuum packaging the atomic clock system provided in this application embodiment, the method comprising:

[0096] Step 101: Assemble the connecting components, optical path structure, and base to obtain the assembled structure;

[0097] Step 102: Heat the solder ring to the reflow temperature, heat the cap to the activation temperature, and ensure that the solder ring and the cap are both at the same target temperature at the same time.

[0098] Step 103: At the target time, the second step of the base and the cap are connected by the solder ring in a vacuum environment;

[0099] Wherein, the reflow temperature is the reflow temperature of the solder ring, and the activation temperature is the activation temperature of the getter on the inner wall of the cap.

[0100] It should be understood that at the target time, the second step of the base and the cap are connected by the solder ring to obtain the atomic clock system provided in this application embodiment.

[0101] The inner wall of the cap is coated with a getter. The reflow temperature and activation temperature are determined based on the specific solder ring material and getter material selection. The reflow temperature may be greater than, equal to, or less than the activation temperature.

[0102] It should be noted that the getter needs to be activated at the activation temperature. After activation, the getter can draw gas at low temperatures (below the activation temperature). After the atomic clock system is vacuum-sealed, the getter remains in a gas-drawing state for many years to maintain the vacuum environment inside the atomic clock system.

[0103] In an optional embodiment of this application, heating the solder ring to the reflow temperature and heating the cap to the activation temperature includes: heating the solder ring and the cap in the same temperature zone (the temperature control zone of the vacuum). If the reflow temperature and the activation temperature are different, one of the solder ring and the cap can be heated for a period of time first, and then the other can be moved to the same temperature zone for heating together. Alternatively, if the activation temperature is lower than the reflow temperature, the solder ring and the cap can be placed in the same temperature zone and heated simultaneously. This simplifies the setting of the temperature zone, allowing heating of the solder ring and the cap to be achieved using only one temperature zone, making the entire vacuum packaging process simpler and more reliable.

[0104] In this embodiment, at the target time, the base and the cap are connected by the solder ring in a vacuum environment. Specifically, at the target time, the assembly structure, which has been heated to the reflow temperature, is moved by the device alignment component and the operating component so that the opening surface of the cap is fitted and fixed to the second step of the base.

[0105] In another optional embodiment of this application, heating the solder ring to the reflow temperature and heating the cap to the activation temperature includes: placing the assembly structure in a first temperature zone and placing the solder ring in the second step of the base, heating the first temperature zone to heat the solder ring to the reflow temperature (at which time the assembly structure is also heated to the reflow temperature); placing the cap in a second temperature zone and heating the second temperature zone to heat the cap to the activation temperature.

[0106] The first and second temperature zones are vacuum-controlled areas with different temperature settings. The solder ring and cap are heated in separate zones: the solder ring in zone I and the cap in zone II. This multi-zone temperature control simplifies and improves the reliability of the entire vacuum packaging process.

[0107] In this embodiment, by heating the solder ring to the reflow temperature and the cap to the activation temperature, and ensuring that both the solder ring and the cap are at the same target reflow temperature, the second step of the base and the cap are connected by the solder ring in a vacuum environment at the target time, which makes the entire vacuum packaging process simpler and more reliable.

[0108] In this embodiment, at the target time, the base and the cap are connected by the solder ring in a vacuum environment. Specifically, at the target time, the cap, which is in the second temperature zone, is transferred to the first temperature zone by the equipment alignment component and the operating component, so that the opening surface of the cap is fitted and fixed to the second step of the base. The first temperature zone and the second temperature zone are both in a vacuum environment.

[0109] Optionally, the control method that ensures the solder ring and the cap are both at the same target temperature at the reflow temperature includes at least one of the following:

[0110] By controlling the timing of temperature changes in the first temperature zone and the second temperature zone, the solder ring and the cap are both at the same target temperature at the reflow temperature.

[0111] By controlling the temperature change rate of the first temperature zone and the temperature change rate of the second temperature zone, the solder ring and the cap are both at the reflow temperature at the same target time.

[0112] The time of temperature change includes at least one of the time of heating up and the time of cooling down;

[0113] The rate of temperature change includes at least one of the heating rate and the cooling rate.

[0114] The heating moment should be understood as the moment when the temperature zone begins to heat up, that is, the moment when the solder ring / cap in the temperature zone begins to be heated.

[0115] The cooling moment should be understood as the moment when the temperature zone begins to cool down, that is, the moment when the solder ring / cap in the temperature zone begins to cool down.

[0116] The duration of temperature change in the first temperature zone can be greater than, equal to, or less than the duration of temperature change in the second temperature zone. Specifically, the duration of temperature rise in the first temperature zone can be greater than, equal to, or less than the duration of temperature rise in the second temperature zone; the duration of temperature drop in the first temperature zone can be greater than, equal to, or less than the duration of temperature drop in the second temperature zone.

[0117] Specifically, for different types of getters and solders, this application provides the following five temperature control schemes. In schemes one through four below, precise temperature control of different temperature zones allows the getter activation process to be completed in one temperature zone, followed by solder reflow soldering in another temperature zone. This multi-temperature zone temperature control vacuum packaging method simplifies and makes the entire vacuum packaging process more reliable. In scheme five below, combining the characteristics of the getter and solder, both are heated simultaneously in the same temperature zone, further simplifying the vacuum packaging process.

[0118] Option 1, wherein the activation temperature is greater than the reflow temperature, the first cooling time of the second temperature zone is greater than the first heating time of the first temperature zone, and the process of heating the solder ring to the reflow temperature by heating the first temperature zone, heating the cap to the activation temperature by heating the second temperature zone, and ensuring that the solder ring and the cap are both at the same target temperature at the same time, includes:

[0119] After heating the cap to the activation temperature to activate the getter, the cap is cooled down.

[0120] From the moment the cap begins to be heated, after a first preset time, the solder ring is heated so that both the solder ring and the cap are at the reflow temperature at the target time;

[0121] Wherein, the first cooling time is the time required for the second temperature zone to drop from the activation temperature to the reflux temperature;

[0122] The first heating time is the time required for the first temperature zone to rise from the degassing temperature to the reflux temperature.

[0123] Option 2, wherein the activation temperature is greater than the reflow temperature, the second cooling time of the second temperature zone is less than the second heating time of the first temperature zone, and the process of heating the solder ring to the reflow temperature by heating the first temperature zone, heating the cap to the activation temperature by heating the second temperature zone, and ensuring that the solder ring and the cap are both at the same target temperature at the same time, includes:

[0124] The solder ring is heated;

[0125] From the moment the solder ring begins to be heated, after a second preset time, the cap is heated to the activation temperature. After the cap is heated to the activation temperature to activate the getter, the cap is cooled down so that the solder ring and the cap are both at the reflow temperature at the target time.

[0126] Wherein, the second cooling time is the time required for the second temperature zone to drop from the activation temperature to the reflux temperature;

[0127] The second heating time is the time required for the first temperature zone to rise from the degassing temperature to the reflux temperature.

[0128] Option 3, wherein the activation temperature is lower than the reflow temperature, the third heating time of the second temperature zone is greater than the fourth heating time of the first temperature zone, and the process of heating the solder ring to the reflow temperature by heating the first temperature zone, heating the cap to the activation temperature by heating the second temperature zone, and ensuring that the solder ring and the cap are both at the same target temperature at the same time, includes:

[0129] After activating the getter by heating the cap to the activation temperature, the cap is further heated.

[0130] After a third preset time period following the start of heating the cap, the solder ring is heated so that both the solder ring and the cap are at the reflow temperature at the target time.

[0131] Wherein, the third heating time is the time required for the second temperature zone to rise from the activation temperature to the reflux temperature;

[0132] The fourth heating time is the time required for the first temperature zone to rise from the degassing temperature to the reflux temperature.

[0133] Option 4, wherein the activation temperature is lower than the reflow temperature, the fifth heating time of the second temperature zone is less than the sixth heating time of the first temperature zone, and the process of heating the solder ring to the reflow temperature by heating the first temperature zone, heating the cap to the activation temperature by heating the second temperature zone, and ensuring that the solder ring and the cap are both at the same target temperature at the same time, includes:

[0134] The solder ring is heated;

[0135] After a fourth preset time period following the start of heating of the solder ring, the cap is heated, and after the cap is heated to the activation temperature to activate the getter, the cap is continued to be heated so that the solder ring and the cap are both at the reflow temperature at the target time.

[0136] Wherein, the fifth heating time is the time required for the second temperature zone to rise from the activation temperature to the reflux temperature;

[0137] The sixth heating time is the time required for the first temperature zone to rise from the degassing temperature to the reflux temperature.

[0138] It should be noted that the degassing temperature in Schemes 1 to 5 refers to the temperature at which the assembly structure and solder ring are heated and degassed in the first temperature zone. Degassing refers to removing air, moisture, and other residual gases adsorbed on the surface of the assembly structure and solder ring. This degassing temperature is lower than the reflow temperature and activation temperature, and is typically greater than 100 degrees Celsius.

[0139] Option 5, wherein the activation temperature is lower than the reflow temperature, and the steps of heating the solder ring to the reflow temperature, heating the cap to the activation temperature, and ensuring that both the solder ring and the cap are at the reflow temperature at the target time, include:

[0140] The assembly structure is placed in a first temperature zone, and the assembly structure is heated by heating the first temperature zone to raise the temperature, and the assembly structure is brought to the reflow temperature at the target time.

[0141] The solder ring is placed on the opening of the cap, and the solder ring and the cap are placed in the second temperature zone. The second temperature zone is heated so that the solder ring and the cap are both at the reflow temperature at the target time.

[0142] The first temperature zone and the second temperature zone are vacuum zones, representing different temperature control areas.

[0143] In Scheme 5, because the activation temperature is lower than the reflow temperature, the solder ring and cap will reach the activation temperature first when heated in the second temperature zone, activating the getter on the inner wall of the cap. After activation, the getter remains activated at high temperatures (temperatures higher than the activation temperature). In this scheme, the heating rates of the first and second temperature zones can be controlled to ensure that both zones reach the reflow temperature at the target time.

[0144] The following is a complete example illustrating the vacuum sealing method provided in the embodiments of this application.

[0145] 1. In one assembly, the first connector, optical path structure, second connector, and base are mounted, and the gold pads of the optical path structure are electrically connected to the gold pads on the surface of the first connector.

[0146] 2. Pretreatment: High-purity nitrogen is used to purge the structure, caps and solder rings assembled in the first stage to remove particulate contaminants that were originally present on the surface of the structure and introduced during the first stage of assembly.

[0147] 3. Secondary assembly: The pre-processed structural components are assembled and placed in a multi-temperature zone controlled packaging device using special fixtures and jigs.

[0148] (1) The assembled structure and solder ring are placed into the workpiece position of the heating zone I (first temperature zone) of the packaging equipment using special fixtures and jigs.

[0149] (2) Using a special fixture and jig, place the cap containing the getter into the workpiece position of the heating zone II (second temperature zone) of the packaging equipment. The gold plating layer on the opening surface of the cap and the gold plating layer on the second step of the base are basically the same in area and shape. After the cap is placed, the gold plating layer on the opening surface of the cap and the gold plating layer on the second step of the base are in a directly opposite position.

[0150] (3) Depending on the temperature control method, the solder ring is placed on the gold-plated surface of the second step of the base or the gold-plated surface of the opening of the tube cap. The thickness of the solder ring can be 20 to 120 micrometers.

[0151] 4. Degassing: Each structural component placed in the vacuum packaging equipment undergoes a heating and degassing process to remove adsorbed air, moisture, and other residual gases from the structural surfaces. The vacuum packaging equipment is evacuated. Once the vacuum level exceeds 5*10⁻³ Pa, the heating functions of heating zone I and heating zone II are activated to heat the workpieces in each zone individually. Based on the thermal damage temperature of the optical path structure, the temperature of heating zone I (first zone) can be set to 100℃~250℃ (250℃ in the example) and below the solder ring reflow temperature. Based on the difference in getter activation temperature, the temperature of heating zone II can be set to 100℃~250℃ (250℃ in the example) and below the getter activation temperature. The degassing time can be set from 2 hours to 10 days (1 day in the example), depending on the selection of the degassing temperature, the required vacuum level of the device, packaging efficiency, and time cost. A longer degassing time, higher degassing temperature, higher degassing rate, and higher vacuum level after packaging are achieved.

[0152] 5. Getter Activation: Set the temperature of heating zone II to heat the getter to activate it. Different getter materials require different activation temperatures; the selectable activation temperature range is 150℃ to 450℃. The temperature set in heating zone II can be 150℃ to 450℃ (350℃ in this example), and the getter activation time varies from 10 minutes to 2 days (1 hour in this example).

[0153] 6. Eutectic welding: Precisely control the temperatures of heating zones I and II to melt the solder ring, completing the reflow welding of the base and cap. Different solder materials require different reflow temperatures; the selectable reflow temperature range is 150℃~350℃ (300℃ in this example). Various temperature control schemes can be selected by combining different reflow temperatures with different getter activation temperatures. The following detailed explanation uses a fixed heating and cooling rate for zones I and II. The heating rate can be selected from 10~90℃ / min, and the cooling rate can be selected from 10~90℃ / min (in this example, the heating rate for zone I is 50℃ / min, and the cooling rate for zone II is 50℃ / min).

[0154] (1) Temperature control scheme one: The solder ring is placed in temperature zone I and the cap is placed in temperature zone II. The activation temperature is greater than the reflow temperature. The cooling time of temperature zone II is greater than the heating time of temperature zone I. After the getter is activated, temperature zone II can be cooled down immediately. After temperature zone II is cooled down for a period of time, temperature zone I can be heated up. By controlling this time point, the temperatures of temperature zone I and temperature zone II can reach the reflow temperature at the same time.

[0155] (2) Temperature Control Scheme Two: The solder ring is placed in temperature zone I, and the cap is placed in temperature zone II. The activation temperature is higher than the reflow temperature, and the cooling time of temperature zone II is shorter than the heating time of temperature zone I. Temperature zone I can be preheated before the getter activation is complete. After the getter activation is complete, temperature zone II is immediately cooled. By controlling the preheating time of temperature zone I, the temperatures of temperature zone I and temperature zone II reach the reflow temperature at the same time. (In the example, the activation temperature of 350℃ is higher than the reflow temperature of 300℃, and the time for temperature zone II to drop from 350℃ to 300℃ is 1 minute, which is shorter than the time for temperature zone I to rise from 150℃ to 300℃ in 3 minutes.)

[0156] (3) Temperature control scheme three: The solder ring is placed in temperature zone I and the cap is placed in temperature zone II. The activation temperature is lower than the reflow temperature. The heating time of temperature zone II is longer than that of temperature zone I. Temperature zone II can be heated immediately before the getter activation is completed. After temperature zone II is heated for a period of time, temperature zone I is heated. By controlling this time point, the temperatures of temperature zone I and temperature zone II reach the reflow temperature T2 at the same time.

[0157] (4) Temperature control scheme four: The solder ring is placed in temperature zone I and the cap is placed in temperature zone II. The activation temperature is lower than the reflow temperature and the heating time of temperature zone II is shorter than that of temperature zone I. Temperature zone I can be heated in advance before the getter activation is completed. After the getter activation is completed, temperature zone II is heated immediately. By controlling the heating time of temperature zone I in advance, the temperatures of temperature zone I and temperature zone II can reach the reflow temperature at the same time.

[0158] (5) Temperature control scheme five: The solder ring is placed in temperature zone II, the cap is placed in temperature zone II, the activation temperature is lower than the reflow temperature, and after activation, temperature zone I and temperature zone II are immediately heated. By controlling the heating rate of temperature zone I and temperature zone II, temperature zone I and temperature zone II reach the reflow temperature at the same time.

[0159] After temperature zones I and II reach their reflow temperatures simultaneously using the five temperature control methods described above, the tube cap and special fixture in zone II are immediately transferred to zone I via the alignment and operating components of the equipment. The alignment error is required to be less than ±0.1mm. This allows the protruding part of the primary assembly structure to enter the tube cap cavity, and the opening surface of the tube cap to be fully fitted with the second step surface of the base. After holding zone I at this temperature for 0–30 minutes (10 minutes in this example), zone I is cooled down at a rate of 10℃ / min–90℃ / min (50℃ / min in this example). When the temperature is reduced to 50℃–300℃ below the solder reflow temperature (200℃ in this example), the cavity is opened and the encapsulated component is removed. The vacuum encapsulation of the atomic clock system is then complete.

[0160] See Figure 8 This application provides a vacuum sealing device 200, comprising:

[0161] The first assembly module 201 is used to assemble the connecting components, optical path structure and base to obtain the assembly structure;

[0162] Heating module 202 is used to heat the solder ring to the reflow temperature, heat the cap to the activation temperature, and ensure that the solder ring and the cap are both at the reflow temperature at the same target time;

[0163] The second assembly module 203 is used to connect the second step of the base and the cap through the solder ring in a vacuum environment at the target time.

[0164] Wherein, the reflow temperature is the reflow temperature of the solder ring, and the activation temperature is the activation temperature of the getter on the inner wall of the cap.

[0165] Optionally, the heating module 202 includes:

[0166] The first placement unit is used to place the assembly structure in the first temperature zone and place the solder ring in the second step of the base;

[0167] The second placement unit is used to place the cap in the second temperature zone;

[0168] The heating unit heats the solder ring to the reflow temperature by heating the first temperature zone, and heats the cap to the activation temperature by heating the second temperature zone, ensuring that the solder ring and the cap are both at the reflow temperature at the same target time.

[0169] The first temperature zone and the second temperature zone are vacuum zones, representing different temperature control areas.

[0170] Optionally, the control method that ensures the solder ring and the cap are both at the same target temperature at the reflow temperature includes at least one of the following:

[0171] By controlling the timing of temperature changes in the first temperature zone and the second temperature zone, the solder ring and the cap are both at the same target temperature at the reflow temperature.

[0172] By controlling the temperature change rate of the first temperature zone and the temperature change rate of the second temperature zone, the solder ring and the cap are both at the reflow temperature at the same target time.

[0173] The time of temperature change includes at least one of the time of heating up and the time of cooling down;

[0174] The rate of temperature change includes at least one of the heating rate and the cooling rate.

[0175] Optionally, the activation temperature is greater than the reflow temperature, the first cooling time of the second temperature zone is greater than the first heating time of the first temperature zone, and the heating unit includes:

[0176] After heating the cap to the activation temperature to activate the getter, the cap is cooled down.

[0177] From the moment the cap begins to be heated, after a first preset time, the solder ring is heated so that both the solder ring and the cap are at the reflow temperature at the target time;

[0178] Wherein, the first cooling time is the time required for the second temperature zone to drop from the activation temperature to the reflux temperature;

[0179] The first heating time is the time required for the first temperature zone to rise from the degassing temperature to the reflux temperature.

[0180] Optionally, the activation temperature is greater than the reflow temperature, the second cooling time of the second temperature zone is less than the second heating time of the first temperature zone, and the heating unit includes:

[0181] The solder ring is heated;

[0182] From the moment the solder ring begins to be heated, after a second preset time, the cap is heated to the activation temperature. After the cap is heated to the activation temperature to activate the getter, the cap is cooled down so that the solder ring and the cap are both at the reflow temperature at the target time.

[0183] Wherein, the second cooling time is the time required for the second temperature zone to drop from the activation temperature to the reflux temperature;

[0184] The second heating time is the time required for the first temperature zone to rise from the degassing temperature to the reflux temperature.

[0185] Optionally, the activation temperature is lower than the reflux temperature, the third heating time of the second temperature zone is greater than the fourth heating time of the first temperature zone, and the heating unit includes:

[0186] After activating the getter by heating the cap to the activation temperature, the cap is further heated.

[0187] After a third preset time period following the start of heating the cap, the solder ring is heated so that both the solder ring and the cap are at the reflow temperature at the target time.

[0188] Wherein, the third heating time is the time required for the second temperature zone to rise from the activation temperature to the reflux temperature;

[0189] The fourth heating time is the time required for the first temperature zone to rise from the degassing temperature to the reflux temperature.

[0190] Optionally, the activation temperature is lower than the reflux temperature, the fifth heating time of the second temperature zone is shorter than the sixth heating time of the first temperature zone, and the heating unit includes:

[0191] The solder ring is heated;

[0192] After a fourth preset time period following the start of heating of the solder ring, the cap is heated, and after the cap is heated to the activation temperature to activate the getter, the cap is continued to be heated so that the solder ring and the cap are both at the reflow temperature at the target time.

[0193] Wherein, the fifth heating time is the time required for the second temperature zone to rise from the activation temperature to the reflux temperature;

[0194] The sixth heating time is the time required for the first temperature zone to rise from the degassing temperature to the reflux temperature.

[0195] Optionally, the activation temperature is lower than the reflow temperature, and the heating module 202 includes:

[0196] The assembly structure is placed in a first temperature zone, and the assembly structure is heated by heating the first temperature zone to raise the temperature, and the assembly structure is brought to the reflow temperature at the target time.

[0197] The solder ring is placed on the opening of the cap, and the solder ring and the cap are placed in the second temperature zone. The second temperature zone is heated so that the solder ring and the cap are both at the reflow temperature at the target time.

[0198] The first temperature zone and the second temperature zone are vacuum zones, representing different temperature control areas.

[0199] The vacuum sealing apparatus 200 provided in this application embodiment can realize all the processes that can be realized in the vacuum sealing method embodiment of this application, and achieve the same beneficial effects. To avoid repetition, it will not be described again here.

[0200] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. A vacuum packaging method for packaging an atomic clock system, characterized in that, The atomic clock system includes: a housing, connecting components, and an optical path structure; Both the connecting component and the optical path structure are located in a sealed cavity within the housing. The inner wall of the housing forming the cavity is provided with a first step. The optical path structure is fixedly connected to the first step through the connecting component. There is a gap between the optical path structure and the inner wall. The housing includes a base, a cap, and a solder ring. The base has a first step and a second step. The second step and the cap are connected in a sealed manner by the solder ring to form the cavity. The inner wall of the cap is coated with a getter. There are gaps between the optical path structure and the inner wall of the base and the inner wall of the cap. The method includes: Assemble the connecting component, the optical path structure, and the base to obtain the assembly structure; The solder ring is heated to the reflow temperature, the cap is heated to the activation temperature, and the solder ring and the cap are both at the reflow temperature at the same target time. At the target time, the second step of the base and the cap are connected by the solder ring in a vacuum environment; Wherein, the reflow temperature is the reflow temperature of the solder ring, and the activation temperature is the activation temperature of the getter on the inner wall of the cap.

2. The method according to claim 1, characterized in that, The step of heating the solder ring to the reflow temperature, heating the cap to the activation temperature, and ensuring that the solder ring and the cap are both at the same target temperature at the same time includes: The assembly structure is placed in the first temperature zone, and the solder ring is placed in the second step of the base; Place the cap in the second temperature zone; The solder ring is heated to the reflow temperature by heating the first temperature zone, and the cap is heated to the activation temperature by heating the second temperature zone, so that the solder ring and the cap are both at the reflow temperature at the same target time; The first temperature zone and the second temperature zone are vacuum zones, representing different temperature control areas.

3. The method according to claim 2, characterized in that, The control method that ensures that the solder ring and the cap are both at the same target temperature at the same reflow temperature includes at least one of the following: By controlling the timing of temperature changes in the first temperature zone and the second temperature zone, the solder ring and the cap are both at the same target temperature at the reflow temperature. By controlling the temperature change rate of the first temperature zone and the temperature change rate of the second temperature zone, the solder ring and the cap are both at the reflow temperature at the same target time. The time of temperature change includes at least one of the time of heating up and the time of cooling down; The rate of temperature change includes at least one of the heating rate and the cooling rate.

4. The method according to claim 2, characterized in that, The activation temperature is greater than the reflow temperature, the first cooling time of the second temperature zone is greater than the first heating time of the first temperature zone, and the step of heating the solder ring to the reflow temperature by heating the first temperature zone, heating the cap to the activation temperature by heating the second temperature zone, and ensuring that the solder ring and the cap are both at the same target temperature at the same time includes: After heating the cap to the activation temperature to activate the getter, the cap is cooled down. From the moment the cap begins to be heated, after a first preset time, the solder ring is heated so that both the solder ring and the cap are at the reflow temperature at the target time; Wherein, the first cooling time is the time required for the second temperature zone to drop from the activation temperature to the reflux temperature; The first heating time is the time required for the first temperature zone to rise from the degassing temperature to the reflux temperature.

5. The method according to claim 2, characterized in that, The activation temperature is greater than the reflow temperature, the second cooling time of the second temperature zone is less than the second heating time of the first temperature zone, and the step of heating the solder ring to the reflow temperature by heating the first temperature zone, heating the cap to the activation temperature by heating the second temperature zone, and ensuring that the solder ring and the cap are both at the same target temperature at the same time includes: The solder ring is heated; From the moment the solder ring begins to be heated, after a second preset time, the cap is heated to the activation temperature. After the cap is heated to the activation temperature to activate the getter, the cap is cooled down so that the solder ring and the cap are both at the reflow temperature at the target time. Wherein, the second cooling time is the time required for the second temperature zone to drop from the activation temperature to the reflux temperature; The second heating time is the time required for the first temperature zone to rise from the degassing temperature to the reflux temperature.

6. The method according to claim 2, characterized in that, The activation temperature is lower than the reflow temperature, the third heating time of the second temperature zone is greater than the fourth heating time of the first temperature zone, and the step of heating the solder ring to the reflow temperature by heating the first temperature zone, heating the cap to the activation temperature by heating the second temperature zone, and ensuring that the solder ring and the cap are both at the same target temperature at the same time includes: After activating the getter by heating the cap to the activation temperature, the cap is further heated. After a third preset time period following the start of heating the cap, the solder ring is heated so that both the solder ring and the cap are at the reflow temperature at the target time. Wherein, the third heating time is the time required for the second temperature zone to rise from the activation temperature to the reflux temperature; The fourth heating time is the time required for the first temperature zone to rise from the degassing temperature to the reflux temperature.

7. The method according to claim 2, characterized in that, The activation temperature is lower than the reflow temperature, the fifth heating time of the second temperature zone is less than the sixth heating time of the first temperature zone, and the step of heating the solder ring to the reflow temperature by heating the first temperature zone, heating the cap to the activation temperature by heating the second temperature zone, and ensuring that the solder ring and the cap are both at the same target temperature at the same time includes: The solder ring is heated; After a fourth preset time period following the start of heating of the solder ring, the cap is heated, and after the cap is heated to the activation temperature to activate the getter, the cap is continued to be heated so that the solder ring and the cap are both at the reflow temperature at the target time. Wherein, the fifth heating time is the time required for the second temperature zone to rise from the activation temperature to the reflux temperature; The sixth heating time is the time required for the first temperature zone to rise from the degassing temperature to the reflux temperature.

8. The method according to claim 1, characterized in that, The activation temperature is lower than the reflow temperature. Heating the solder ring to the reflow temperature, heating the cap to the activation temperature, and ensuring that both the solder ring and the cap are at the reflow temperature at the target time includes: The assembly structure is placed in a first temperature zone, and the assembly structure is heated by heating the first temperature zone to raise the temperature, and the assembly structure is brought to the reflow temperature at the target time. The solder ring is placed on the opening of the cap, and the solder ring and the cap are placed in the second temperature zone. The second temperature zone is heated so that the solder ring and the cap are both at the reflow temperature at the target time. The first temperature zone and the second temperature zone are vacuum zones, representing different temperature control areas.

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