Vacuum packaging method of electric field sensor and electric field sensor

Abstract

The invention provides a vacuum packaging method of an electric field sensor and the electric field sensor, and the packaging method comprises the steps: arranging a getter on the bottom end surface of a packaging cover plate; in a vacuum heating state, the electric field sensitive chip is fixed in the packaging tube shell; electrically connecting the electric field sensitive chip with a specified welding spot part in the packaging tube shell; and in a vacuum state, activating the getter, buckling the packaging cover plate, and fixing the packaging cover plate on the open end face of the packaging tube shell. According to the invention, the vacuum packaging effect of the electric field sensor can be ensured, the quality factor of the electric field sensitive chip is improved, and meanwhile, the welding void rate of the joint between the packaging cover plate and the packaging tube shell can be reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of vacuum packaging, and in particular to a vacuum packaging method of an electric field sensor and the electric field sensor. Background Art

[0002] Electric field measurement has a wide range of applications in aerospace, meteorology, smart grid, industrial production and other fields. Micro electric field sensors based on micro-electro-mechanical systems (MEMS) technology have become the development trend and research hotspot of electric field sensors due to their outstanding advantages such as small size, low power consumption, low cost, easy mass production and easy integration.

[0003] A paper titled "Chip-Scale Vacuum Packaging and Testing of a Resonant Micro Electric Field Sensor" was published in the September 2015 issue of the Journal of Electronics & Information Technology. The paper states: "To reduce the sensor's driving voltage and improve its quality factor (Q value) and signal-to-noise ratio, this paper combines a gold-tin and gold-silicon alloy solder packaging process with a getter and eutectic bonding technology to achieve chip-scale vacuum packaging of the electric field sensor." Experimental results show that the packaged electric field sensor achieves a quality factor (Q value) of 30,727.4.

[0004] However, with the continuous increase in the application fields of electric field sensors, the electric field sensors with the above-mentioned quality factor (i.e., Q value) can no longer meet the needs in related fields. Therefore, how to ensure the vacuum packaging effect of electric field sensors and improve the quality factor (i.e., Q value) of electric field sensitive chips is a technical problem that needs to be solved urgently. Summary of the Invention

[0005] In order to solve the above-mentioned problems, the present invention provides a vacuum packaging method and an electric field sensor, which ensure the vacuum packaging effect of the electric field sensor and improve the quality factor of the electric field sensitive chip.

[0006] To achieve the above objectives, in a first aspect, the present invention provides a vacuum packaging method for an electric field sensor, comprising the following steps:

[0007] Disposing a getter on the bottom end surface of the packaging cover plate;

[0008] Under vacuum heating conditions, the electric field sensitive chip is fixed in the package tube shell;

[0009] Electrically connecting the electric field sensitive chip to a designated solder joint portion in the package shell;

[0010] Under vacuum conditions, the getter is activated, and the package cover is buckled and fixed on the open end surface of the package shell.

[0011] In one embodiment, the step of fixing the electric field sensitive chip in the package under vacuum heating comprises the following steps:

[0012] Placing the electric field sensitive chip in the soldering area of ​​the package shell;

[0013] The interior of the eutectic furnace is preheated under vacuum for a preset time;

[0014] The internal temperature of the eutectic furnace is continuously controlled at the melting temperature of the soldering medium, and the electric field sensitive chip is fixed in the soldering area by the melted soldering medium.

[0015] In one embodiment, activating the getter under vacuum and fastening and fixing the package cover to the open end surface of the package shell comprises the following steps:

[0016] Placing the packaging cover plate with the getter attached thereto in a lower tooling, and placing the packaging tube shell in an upper tooling;

[0017] Buckling the upper tooling and the lower tooling together so that the package cover is buckled onto the open end surface of the package shell and one end surface of the connecting portion contacts the package shell;

[0018] The interior of the eutectic furnace is preheated under vacuum for a preset time;

[0019] Under vacuum conditions, continuously controlling the internal temperature of the eutectic furnace to a getter activation temperature to activate the getter;

[0020] Under vacuum conditions, the internal temperature of the eutectic furnace is continuously controlled at the melting temperature of the connection portion, and the package cover is buckled and fixed to the open end surface of the package shell through the melted connection portion.

[0021] In one embodiment, activating the getter under vacuum and fastening and fixing the package cover to the open end surface of the package shell comprises the following steps:

[0022] Placing the packaging cover plate with the getter attached thereto in a lower tooling, and placing the packaging tube shell in an upper tooling;

[0023] In a vacuum state, continuously applying current to the getter to activate the getter;

[0024] Buckling the upper tooling and the lower tooling together so that the package cover is buckled onto the open end surface of the package shell and one end surface of the connecting portion contacts the package shell;

[0025] The interior of the eutectic furnace is preheated under vacuum for a preset time;

[0026] Under vacuum conditions, the internal temperature of the eutectic furnace is continuously controlled at the melting temperature of the connection portion, and the package cover is buckled and fixed to the open end surface of the package shell through the melted connection portion.

[0027] In a second aspect, the present invention further provides a vacuum packaging method for an electric field sensor, comprising the following steps:

[0028] Under vacuum conditions, activating the getter on the package cover;

[0029] Under vacuum heating conditions, the electric field sensitive chip is fixed in the package tube shell;

[0030] Electrically connecting the electric field sensitive chip to a designated solder joint portion in the package shell;

[0031] Under vacuum heating, the packaging cover is buckled and fixed on the open end surface of the packaging tube shell.

[0032] In one embodiment, activating the getter on the package cover under a vacuum state includes:

[0033] In a vacuum state, continuously applying current to the getter to activate the getter;

[0034] Alternatively, in a vacuum state, the internal temperature of the eutectic furnace is continuously controlled to be at a getter activation temperature to activate the getter.

[0035] In a third aspect, the present invention also provides an electric field sensor, which is packaged by the vacuum packaging method of an electric field sensor according to any one of claims 1 to 6, and is characterized in that it includes a packaging cover, a packaging tube shell and an electric field sensitive chip, the packaging cover is fastened through a melted connection portion and fixed on the open end surface of the packaging tube shell to form a packaging structure of the electric field sensitive chip and provide space for placing the electric field sensitive chip, the packaging cover includes a cover plate and a getter arranged on the cover body.

[0036] In one embodiment, an inner convex portion is formed on a local area of ​​the bottom end surface of the cover plate, and the getter is provided on the bottom end surface of the inner convex portion, wherein:

[0037] The inner convex portion includes a first side wall surface a and a first side wall surface b. When the packaging cover is buckled and fixed to the open end surface of the packaging tube shell, the first side wall surface a is adjacent to the inner side wall surface of the packaging tube shell, and the first side wall surface b is adjacent to the other inner side wall surface of the packaging tube shell.

[0038] In one embodiment, the bottom end surface of the cover plate further includes a contact area surrounding the outer side of the inner protrusion, and the connecting portion is fixed on the contact area and surrounds the outer side of the inner protrusion.

[0039] In one embodiment, a plurality of solder joints are provided on the bottom plate of the package shell, and the electric field sensitive chip is connected to designated solder joints via connecting leads, wherein:

[0040] After each solder point portion passes through the bottom plate of the package tube shell, the top end surface of each solder point portion extends into the space to form an internal end, and the internal end is electrically connected to the electric field sensitive chip through the connecting lead, and the bottom end surface of each solder point portion is in the same plane as the bottom end surface of the package tube shell;

[0041] Alternatively, after each of the solder joints penetrates the bottom plate of the packaging tube shell, the top end surface of the solder joint and the inner wall surface of the bottom plate of the packaging tube shell are in the same plane to form a built-in end, and the built-in end is electrically connected to the electric field sensitive chip through the connecting lead, and the bottom end surface of each of the solder joints is in the same plane as the bottom end surface of the packaging tube shell.

[0042] In one embodiment, a local area of ​​the inner wall surface of the bottom plate of the package tube shell extends upward to form a frame-shaped boss, wherein:

[0043] The top end surface of the built-in end is located in an area above the top end surface of the frame-shaped boss, or the top end surface of the built-in end is located in the same plane as the top end surface of the frame-shaped boss.

[0044] Compared with the prior art, the present invention has one of the following advantages:

[0045] 1. In the above vacuum packaging method, since the steps of activating the getter, fixing the electric field sensitive chip in the packaging tube shell, and fixing the packaging cover plate to the open end surface of the packaging tube shell are all completed in a vacuum environment, the vacuum packaging effect of the electric field sensor can be ensured, the quality factor of the electric field sensitive chip can be improved, and the solder void rate at the connection between the packaging cover plate and the packaging tube shell can be reduced.

[0046] 2. Using electrical activation to activate the getter can avoid affecting the fixing performance of the electric field sensitive chip. When using heating to activate the getter, since the activation temperature of the getter is lower than the melting temperature of the connection part, the connection part can also be preheated during the activation of the getter to shorten the melting time of the connection part and improve efficiency.

[0047] 3. By adding an inner convex portion to the bottom end surface of the package cover, when the package cover is buckled onto the open end surface of the package tube shell, the inner convex portion and the getter will discharge part of the gas in the space, thereby reducing the gas volume in the space, improving the gas extraction efficiency and the vacuum packaging efficiency of the electric field sensor;

[0048] 4. The inner convex portion is arranged on the bottom end surface of the package cover plate, which will not affect the electrical connection between the electric field sensitive chip, the connecting lead and the solder joint;

[0049] 5. Since both ends of the inner convex portion are adjacent to the inner wall surface of the package shell, it is also convenient to locate the fastening position of the package cover when the package cover is fastened to the open end surface of the package shell;

[0050] 6. Since the bottom end surface of the inner convex portion is located below the bottom end surface of the welding ring, the inner convex portion can also reduce the probability of the welding ring being damaged due to collision. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 This is a first exemplary flow chart of the vacuum packaging method of the present invention;

[0052] Figure 2 is a second exemplary flow chart of the vacuum packaging method of the present invention;

[0053] Figure 3 An exploded view of the processing tooling of the present invention;

[0054] Figure 4 is a cross-sectional view of a first example of an electric field sensor according to the present invention;

[0055] Figure 5 is a cross-sectional view of a second example of the electric field sensor of the present invention;

[0056] Figure 6 is a cross-sectional view of a third example of the electric field sensor of the present invention;

[0057] Figure 7 is a cross-sectional view of a fourth example of the electric field sensor according to the present invention.

[0058] The main reference numerals are as follows:

[0059] 1-package cover; 100-cover; 101-inner core; 102-inner convex portion; 103-getter; 104-welding ring;

[0060] 2-Electric field sensitive chip; 3-Packaging tube shell; 300-First column; 301-Second column; 302-Base plate; 303-Metal area a; 304-Metal area b; 305-Frame-shaped boss; 4-Connecting lead; 5-Soldering point; 6-Upper tooling; 600-Base; 601-First receiving groove; 602-Stud; 603-Positioning groove; 7-Lower tooling; 700-Second receiving groove; 701-Positioning column; 8-Space. DETAILED DESCRIPTION

[0061] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0062] In the description of the present invention, it should be understood that the terms "upper", "lower", "top surface", "bottom surface", "inside", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. It should be noted that when a component is considered to be "connected" to another component, it can be directly connected to the other component or there may be a centrally arranged component at the same time. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0063] Example 1

[0064] like Figure 1 As shown, this embodiment provides a vacuum packaging method for packaging the electric field sensors in the above-mentioned embodiments 1 to 4, comprising the following steps:

[0065] S1. Arrange a getter on the bottom end surface of the package cover.

[0066] Specifically, the getter is disposed on the bottom end surface of the inner convex portion by magnetron sputtering.

[0067] S2. Under vacuum heating conditions, the electric field sensitive chip is fixed in the packaging tube shell.

[0068] Specifically, step S2 includes the following sub-steps:

[0069] The electric field sensitive chip that meets the requirements after screening is placed on the metal area b (i.e., the welding area) in the package tube shell, wherein solder or silver glue (i.e., the welding medium) is provided between the electric field sensitive chip and the metal area b for fixing the two;

[0070] Extract the gas inside the eutectic furnace and the space to ensure that the interior of the eutectic furnace reaches a vacuum state, and continue to preheat the interior of the eutectic furnace for a preset time;

[0071] The melting temperature of the solder or silver paste inside the eutectic furnace is continuously controlled at 200°C to 270°C. After a preset time, the solder or silver paste reaches its melting point, allowing the electric field sensitive chip to be attached to the top end surface of the metal area b through the solder or silver paste, thereby fixing it in the package tube shell.

[0072] S3. Electrically connect the electric field sensitive chip to the designated solder joint portion in the package shell.

[0073] Specifically, in step 3, a plurality of solder joints are fixed on the bottom plate of the package shell, and welding techniques such as gold wire ball welding are used to weld the electric field sensitive chip to the designated solder joints through the connecting leads to achieve electrical connection between the electric field sensitive chip and the package shell.

[0074] Since each soldering point is connected to the external circuit board respectively, the electric field sensitive chip is connected to the external circuit board via the connecting leads and the soldering point, thereby transmitting relevant signals.

[0075] S4. Place the packaging cover plate and the packaging tube shell in a tooling, activate the getter under vacuum, and buckle and fix the packaging cover plate on the open end surface of the packaging tube shell.

[0076] Specifically, step S4 includes the following sub-steps:

[0077] Place the package cover plate with the getter attached in the lower tooling, and place the package tube shell in the upper tooling;

[0078] Buckle the upper tooling and the lower tooling together so that the package cover is buckled onto the open end surface of the package shell, and the solder ring (i.e., the connecting portion) contacts the metal area a located on the top end surface of the package shell;

[0079] Place the device with the package cover plate and the package shell fixed in the eutectic furnace, evacuate the interior of the eutectic furnace, ensure that the interior of the eutectic furnace reaches a vacuum state, and then preheat the interior of the eutectic furnace for a preset time;

[0080] Ensure that the interior and space of the eutectic furnace are in a vacuum state, and continuously control the internal temperature of the eutectic furnace to the getter activation temperature to activate the getter;

[0081] Ensure that the interior and space of the eutectic furnace are in a vacuum state, and adjust the temperature inside the eutectic furnace from the activation temperature of the getter to the melting temperature of the solder ring (i.e., the melting temperature of the connecting portion). After the preset time is reached, the solder ring reaches the melting point, allowing the package cover to be buckled and fixed on the open end surface of the package tube shell.

[0082] In addition, in another embodiment, step S4 includes the following sub-steps:

[0083] Place the package cover plate with the getter attached in the lower tooling, and place the package tube shell in the upper tooling;

[0084] In a vacuum state, continuously applying current to the getter to activate the getter;

[0085] Buckle the upper tooling and the lower tooling together so that the package cover is buckled onto the open end surface of the package shell, and the solder ring (i.e., the connecting portion) contacts the metal area a located on the top end surface of the package shell;

[0086] Extract the gas inside the eutectic furnace and the space to ensure that the interior of the eutectic furnace reaches a vacuum state, preheat the interior of the eutectic furnace, and preheat for a preset time;

[0087] Ensure that the interior and space of the eutectic furnace are in a vacuum state, and continuously control the internal temperature of the eutectic furnace to the getter activation temperature to activate the getter;

[0088] Ensure that the interior and space of the eutectic furnace are in a vacuum state, and adjust the temperature inside the eutectic furnace from the activation temperature of the getter to the melting temperature of the solder ring (i.e., the melting temperature of the connecting portion). After the preset time is reached, the solder ring reaches the melting point, allowing the package cover to be buckled and fixed on the open end surface of the package tube shell.

[0089] For example, the above step S2 includes:

[0090] S201, placing the electric field sensitive chip on the metal area b (i.e., the welding area) in the package shell, and providing solder between the electric field sensitive chip and the metal area b for fixing the two;

[0091] S202, placing the package tube shell with the electric field sensitive chip in it in a eutectic furnace, extracting the gas inside the eutectic furnace and in the space to ensure that the interior of the eutectic furnace reaches a vacuum state, controlling the internal temperature of the eutectic furnace at 120° C., and preheating for 30 minutes;

[0092] S203 , controlling the internal temperature of the eutectic furnace at 270° C. and maintaining it for 30 minutes, so that the solder reaches the melting point, and the electric field sensitive chip is fixed on the top end surface of the metal region b, thereby being fixed in the package tube shell.

[0093] In addition, in step S2, if silver glue is used to fix the electric field sensitive chip on the metal area b of the package shell, the following steps are included:

[0094] S201, placing the electric field sensitive chip on the metal area b (i.e., the welding area) in the package tube shell, and providing silver glue between the electric field sensitive chip and the metal area b for fixing the two;

[0095] S202, placing the package tube shell with the electric field sensitive chip in it in an oven, evacuating the gas inside the oven, and after ensuring that the interior of the oven reaches a vacuum state, controlling the internal temperature of the oven at 140° C. and preheating for 30 minutes;

[0096] S203 , controlling the internal temperature of the eutectic furnace at 200° C. and maintaining it for 60 minutes, so that the silver glue reaches the melting point, and the electric field sensitive chip is fixed on the top end surface of the metal region b, thereby being fixed in the package tube shell.

[0097] Exemplarily, the above step S4 includes:

[0098] S401, placing the package cover plate with the getter attached in the lower tooling, and placing the package tube shell in the upper tooling;

[0099] S402, fastening the upper tooling and the lower tooling, so that the package cover is fastened to the open end surface of the package shell, and the solder ring contacts the metal area a located on the top end surface of the first pillar and the metal area a located on the top end surface of the second pillar respectively;

[0100] S403, placing the fastened upper and lower tooling devices in a eutectic furnace, evacuating the interior of the eutectic furnace to ensure that the interior of the eutectic furnace reaches a vacuum state, controlling the internal temperature of the eutectic furnace at 120° C., and preheating for 30 minutes;

[0101] S404, ensuring that the interior and space of the eutectic furnace are in a vacuum state, controlling the internal temperature of the eutectic furnace at 250° C., and continuously heating for 40 minutes to activate the getter;

[0102] S405. Ensure that the interior and space of the eutectic furnace are in a vacuum state, control the internal temperature of the eutectic furnace at 300° C., and maintain it for 30 minutes until the solder ring reaches the melting point, so that the package cover is buckled and fixed on the open end surface of the package tube shell.

[0103] In another example, in the above step S4, it includes:

[0104] S401, placing the package cover plate with the getter attached in the lower tooling, and placing the package tube shell in the upper tooling;

[0105] S402. Place the upper tooling and the lower tooling in the eutectic furnace, evacuate the interior of the eutectic furnace to ensure that the interior of the eutectic furnace reaches a vacuum state, contact the probe with the getter, and continuously apply a current of 3 to 10 A to the getter through the probe for 10 to 30 minutes to activate the getter.

[0106] Preferably, the probe continuously applies a current of 3 A to the getter for 30 minutes to activate the getter.

[0107] S403, fastening the upper tooling and the lower tooling, so that the package cover is fastened to the open end surface of the package shell, and the solder ring contacts the metal area a located on the top end surface of the first column and the metal area a located on the top end surface of the second column respectively;

[0108] S404, placing the fastened upper and lower tooling devices in the eutectic furnace, extracting the gas inside the eutectic furnace and the space to ensure that the interior of the eutectic furnace reaches a vacuum state, controlling the internal temperature of the eutectic furnace at 120° C., and preheating for 30 minutes;

[0109] S405, ensuring that the interior and space of the eutectic furnace are in a vacuum state, controlling the internal temperature of the eutectic furnace at 250° C., and continuously heating for 40 minutes to activate the getter;

[0110] S406. Ensure that the interior and space of the eutectic furnace are in a vacuum state, control the internal temperature of the eutectic furnace at 300° C., and maintain it for 30 minutes until the solder ring reaches the melting point, so that the package cover is buckled and fixed on the open end surface of the package tube shell.

[0111] Example 2

[0112] like Figure 2 As shown, this embodiment provides a vacuum packaging method for packaging the electric field sensors in the above-mentioned embodiments 1 to 4, comprising the following steps:

[0113] S1`, activating the getter on the package cover under vacuum;

[0114] S2`, in a vacuum heating state, fixing the electric field sensitive chip in the packaging tube shell;

[0115] S3`, electrically connecting the electric field sensitive chip to the designated solder joint portion of the package shell;

[0116] S4', placing the packaging cover plate and the packaging tube shell in a tooling, and buckling and fixing the packaging cover plate on the open end surface of the packaging tube shell under vacuum heating.

[0117] Exemplarily, in the above step S1', it includes:

[0118] S101`, disposing a getter on the bottom end surface of the inner convex portion of the package cover plate by magnetron sputtering;

[0119] S102`, placing the package cover plate with the getter attached in a eutectic furnace, extracting the gas inside the eutectic furnace and the space to ensure that the interior of the eutectic furnace reaches a vacuum state, controlling the internal temperature of the eutectic furnace at 120° C., and preheating for 30 minutes;

[0120] S103`, ensuring that the interior and space of the eutectic furnace are in a vacuum state, controlling the internal temperature of the eutectic furnace at 250° C., and continuously heating for 40 minutes to activate the getter.

[0121] In addition, illustratively, the above step S1′ includes:

[0122] S101`, disposing a getter on the bottom end surface of the inner convex portion of the package cover plate by magnetron sputtering;

[0123] S102`, place the package cover plate with the getter attached in the eutectic furnace, extract the gas inside the eutectic furnace and the space to ensure that the interior of the eutectic furnace reaches a vacuum state, and the probe contacts the getter. The probe continuously applies a current of 3 to 10 A to the getter for 10 to 30 minutes to activate the getter.

[0124] Preferably, the probe continuously applies a current of 3 A to the getter for 30 minutes to activate the getter.

[0125] For example, the above step S2′ includes:

[0126] S201′, placing the electric field sensitive chip on the metal area b (i.e., the welding area) in the package shell, and providing solder between the electric field sensitive chip and the metal area b for fixing the two;

[0127] S202`, placing the package tube shell with the electric field sensitive chip in it in a eutectic furnace, extracting the gas inside the eutectic furnace and in the space to ensure that the interior of the eutectic furnace reaches a vacuum state, controlling the internal temperature of the eutectic furnace at 120° C., and preheating for 30 minutes;

[0128] S203 , controlling the internal temperature of the eutectic furnace at 270° C. and maintaining it for 30 minutes, so that the solder reaches the melting point, and the electric field sensitive chip is fixed on the top end surface of the metal region b, thereby being fixed in the package tube shell.

[0129] In addition, in the above step S2', if silver glue is used to fix the electric field sensitive chip in the packaging tube shell, the following steps are included:

[0130] S201′, placing the electric field sensitive chip on the metal area b (i.e., the welding area) in the package tube shell, and providing silver glue between the electric field sensitive chip and the metal area b for fixing the two;

[0131] S202', placing the package tube shell with the electric field sensitive chip in it in an oven, evacuating the gas inside the oven, and after ensuring that the interior of the oven reaches a vacuum state, controlling the internal temperature of the oven at 140° C. and preheating for 30 minutes;

[0132] S203`, control the internal temperature of the oven to 200° C. and maintain it for 60 minutes, so that the silver glue reaches the melting point, and the electric field sensitive chip is fixed on the top end surface of the metal area b, thereby fixing it in the packaging tube shell.

[0133] Illustratively, in the above step S3′, a plurality of solder joints are fixed on the bottom plate of the package shell, and welding techniques such as gold wire ball bonding are used to weld the electric field sensitive chip to the solder joints through the connecting leads, thereby achieving electrical connection between the electric field sensitive chip and the package shell.

[0134] Since each soldering point is connected to the external circuit board respectively, the electric field sensitive chip is connected to the external circuit board via the connecting leads and the soldering point, thereby transmitting relevant signals.

[0135] Exemplarily, in the above step S4', it includes:

[0136] S401', placing the package cover plate with the getter attached in the lower tooling, and placing the package tube shell in the upper tooling;

[0137] S402 , fastening the upper tooling and the lower tooling together so that the package cover is fastened to the open end surface of the package shell, and the solder ring contacts the metal area a located on the top end surface of the first pillar and the metal area a located on the top end surface of the second pillar respectively;

[0138] S403`, placing the fastened upper and lower tooling devices in the eutectic furnace, extracting the gas inside the eutectic furnace and the space to ensure that the interior of the eutectic furnace reaches a vacuum state, controlling the internal temperature of the eutectic furnace at 120° C., and preheating for 30 minutes;

[0139] S404`, ensuring that the interior and space of the eutectic furnace are in a vacuum state, controlling the internal temperature of the eutectic furnace at 300° C. and maintaining it for 30 minutes until the solder ring reaches the melting point, so that the package cover is buckled and fixed on the open end surface of the package tube shell.

[0140] Table 1 is a comparison diagram of electric field sensors packaged using the methods of Example 1 and Example 2 and electric field sensors packaged using other methods.

[0141]

[0142] Based on the above table, it can be seen that, under the condition of the same materials, the vacuum packaging methods described in Example 1 and Example 2 can significantly improve the quality factor of the electric field sensor compared to other existing vacuum packaging methods.

[0143] Specifically, the following method is used to detect the quality factor value of the packaged electric field sensor, including the following steps:

[0144] The electric field sensor is placed in the tooling part, and the electric field sensor processes the sweep frequency signal input by the tooling part and outputs a corresponding frequency signal;

[0145] parsing the received frequency signal according to a preset condition, summarizing the obtained multiple first frequency response values ​​into a first frequency response value set, and drawing a corresponding first waveform image according to the first frequency response value set;

[0146] Analyzing the peak interval frequency signal obtained from the first waveform image according to a preset condition, summarizing the obtained multiple second frequency response values ​​into a second frequency response value set, and drawing a corresponding second waveform image according to the second frequency response value set;

[0147] The resonant frequency value and the passband bandwidth value are determined according to the second waveform image and the second frequency response value set, and the quality factor value of the current electric field sensor is obtained using the following formula:

[0148]

[0149] Example 3

[0150] like Figure 3 As shown, this embodiment provides a processing tool, which is applied to the vacuum packaging method in the above embodiment 1 and the above embodiment 2. The processing tool includes an upper tool 6 for accommodating the package tube shell and a lower tool 7 for accommodating the package cover plate.

[0151] Specifically, the upper tooling 6 includes a base 600 and a fixing member for fixing the package package to the base 600. A first receiving groove 601 for receiving the package package is formed on the bottom end surface of the base 600, and a side through hole is formed on the side wall surface of the base 600, which is connected to the interior of the first receiving groove 601 and is used to receive a portion of the fixing member.

[0152] After the package tube shell is placed inside the first receiving groove 601, the open end surface of the package tube shell is located outside the first receiving groove 601. The position of the fixing member is adjusted so that one end of the fixing member moves into the first receiving groove 601 and abuts against a side wall of the package tube shell. The package tube shell is set inside the first receiving groove 601 under the action of the fixing member, preventing the package tube shell from falling out of the first receiving groove 601 after the upper tooling 6 is flipped longitudinally.

[0153] A second receiving groove 700 for receiving the package cover is formed on the top end surface of the lower tooling 7 , and its position corresponds to that of the first receiving groove 601 .

[0154] Furthermore, at least two positioning grooves 603 are formed on the bottom end surface of the base 600, and at least two positioning posts 701 are provided on the top end surface of the lower tooling 7. The position of one positioning post 701 corresponds to the position of one positioning groove 603, and the position of the other positioning post 701 corresponds to the position of the other positioning groove 603.

[0155] The two positioning grooves 603 and the two positioning posts 701 facilitate positioning of the first receiving groove 601 and the second receiving groove 700 , and can also prevent the first receiving groove 601 and the second receiving groove 700 from moving after positioning, thereby ensuring the vacuum packaging effect of the packaging cover and the packaging tube shell.

[0156] In this embodiment, preferably, the fixing member can be a stud 602, and the side through hole can be a threaded hole. When the end of the stud 602 moves into the first receiving groove 601 and abuts against a side wall of the package shell, the package shell is fixed inside the first receiving groove 601 under the action of the stud 602.

[0157] The package cover and the package shell are fixed by a processing tool, which is opposite to the fixture in the existing packaging process, making it easier to position the package cover and the package shell, thereby ensuring the relative position of the package cover and the package shell after packaging.

[0158] Example 4

[0159] like Figure 4 As shown, this embodiment provides an electric field sensor, which is encapsulated using the vacuum encapsulation method described in the first or second embodiment. The sensor comprises a package cover 1, a package case 3, and an electric field sensitive chip 2. The package cover 1 and package case 3 are secured together to form a package structure for the electric field sensitive chip 2, providing a space 8 for accommodating the electric field sensitive chip 2. The electric field sensitive chip 2 is secured within the package case 3.

[0160] The package cover 1 is made of a metal material, such as Kovar, and the package shell 3 is made of a non-metal material, such as ceramic, plastic, or other non-metal materials.

[0161] The package cover plate 1 includes a cover plate 100, a getter 103, and an inner core 101 extending through the cover plate 100 and the getter 103. The inner core 101 includes an inner convex end adjacent to the electric field sensitive chip 2 and an upper end coplanar with the top end surface of the cover plate 100. An inner convex portion 102 is formed on the bottom end surface of the cover plate 100, and the getter 103 is disposed on the bottom end surface of the inner convex portion 102.

[0162] Preferably, the getter 103 is zirconium-titanium alloy. The electric field sensitive chip 2 can be an electrostatic field sensitive chip or an AC electric field sensitive chip, including a micro-mechanical structure chip made by micro-nano processing technology, a microelectronic sensitive chip, an optical sensitive chip, or other types of sensitive chips.

[0163] The package tube shell 3 is a concave structure with an open top, including a first column 300, a second column 301 and a bottom plate 302. The first column 300 and the second column 301 are both connected to the bottom plate 302, and the three are an integrated structure.

[0164] In this embodiment, specifically, in the package cover plate 1, the center of the cover plate 100 and the center of the inner protrusion 102 are located on the same longitudinal axis. The bottom end surface of the inner protrusion 102 is a horizontal structure and is located above the electric field sensitive chip 2. The getter 103 is fixed to a local area of ​​the bottom end surface of the inner protrusion 102 by magnetron sputtering, or to the entire bottom end surface of the inner protrusion 102. Since an inner convex portion 102 is added to the bottom end face of the packaging cover plate 1, when the packaging cover plate 1 is buckled and fixed to the open end face of the packaging tube shell 3, the inner convex portion 102 and the getter 103 are both placed in the space 8, and will inevitably occupy a part of the area of ​​the space 8. Compared with the packaging structure without the inner convex portion 102 in the prior art, the inner convex portion 102 and the getter 103 cooperate to discharge part of the gas in the space 8 to reduce the gas capacity in the space 8, thereby improving the extraction efficiency of the gas in the space 8, so that the space 8 can quickly reach a vacuum state, and can also improve the vacuum packaging efficiency of the electric field sensor.

[0165] Furthermore, the inner protrusion 102 includes a first side wall surface a and a first side wall surface b. When the packaging cover 1 is buckled and fixed to the open end surface of the packaging tube shell 3, the first side wall surface a is adjacent to the inner wall surface of the first column 300, and the first side wall surface b is adjacent to the inner wall surface of the second column 301.

[0166] Since both ends of the inner protrusion 102 are respectively adjacent to the inner wall surfaces of the first column 300 and the inner wall surfaces of the second column 301 , it is also convenient to locate the fastening position of the package cover 1 when the package cover 1 is fastened to the open end surface of the package tube shell 3 .

[0167] Furthermore, the bottom end surface of the cover plate 100 further includes a contact area surrounding the outer side of the inner protrusion 102 , and a connecting portion for fixing the cover plate 100 to the open end surface of the package tube shell 3 is provided on the contact area.

[0168] Preferably, the bottom end surface of the connecting portion and the bottom end surface of the inner convex portion 102 are in different planes, wherein the bottom end surface of the inner convex portion 102 is located below the bottom end surface of the connecting portion.

[0169] More preferably, the connecting portion is a solder ring 104 made of a gold-tin alloy, which can easily fix the package cover 1 on the open end surface of the package tube shell 3 and improve the fixing performance between the two.

[0170] In this embodiment, specifically, in the packaging tube shell 3, a metal area a303 is provided on the top end surface of the first column 300 and the top end surface of the second column 301. The position of the metal area a303 corresponds to the position of the welding ring 104. Through the matching welding ring 104 and the metal area a303, the packaging cover plate 1 is buckled and fixed on the open end surface of the packaging tube shell 3.

[0171] In the package 3 , a metal area b304 (ie, a welding area) is provided on the top end surface of the base plate 302 , and the electric field sensitive chip 2 is fixed on the top end surface of the base plate 302 via the metal area b304 .

[0172] Solder or adhesive is further interposed between the electric field sensitive chip 2 and the metal region b304 . When the solder or adhesive reaches the melting point, the electric field sensitive chip 2 is fixed inside the package 3 .

[0173] Optionally, the adhesive includes but is not limited to silver glue or silicone glue.

[0174] In addition, a plurality of through holes a are opened on the bottom plate 302 and penetrate the inside thereof. The plurality of through holes a surround the outside of the metal area b304 to form a through hole area.

[0175] After each soldering point portion 5 passes through and is fixed in each through hole a, the top end surface of each soldering point portion 5 is in the same plane as the top end surface of the base plate 302. The top end surface of each soldering point portion 5 is electrically connected to the electric field sensitive chip 2 through the connecting lead 4. The bottom end surface of each soldering point portion 5 is in the same plane as the bottom end surface of the base plate 302, facing the outside of the package tube shell 3, and connected to the external circuit board.

[0176] Since the electric field sensitive chip 2 is connected to the external circuit board via the connecting leads 4 and the solder joints 5 , relevant signals (relevant signals include, but are not limited to, control signals and electric field signals) are transmitted.

[0177] Furthermore, since the through holes a are arranged at intervals, the soldering point portions 5 are also arranged at intervals to form soldering point areas.

[0178] Preferably, each soldering point portion 5 is made of gold-plated material, which makes it easy to solder the connecting lead 4 to the soldering point portion 5 .

[0179] In another possible example, after each soldering point portion 5 passes through each through-hole a, the top end surface of each soldering point portion 5 extends into the space 8 to form an internal end. The internal end is electrically connected to the electric field sensitive chip 2 via the connecting lead 4. The bottom end surface of each soldering point portion 5 is coplanar with the bottom end surface of the base plate 302, faces the outside of the package tube case 3, and is connected to the external circuit board.

[0180] Since the top of each welding point portion 5 is placed inside the space 8, each welding point portion 5 can also occupy a part of the area of ​​the space 8. Combined with the inner protrusion 102 and the getter 103, the gas capacity in the space 8 can be further reduced and the gas extraction efficiency in the space 8 can be improved.

[0181] Example 5

[0182] like Figure 5 As shown, this embodiment provides an electric field sensor, which differs from the above-mentioned fourth embodiment in that:

[0183] Specifically, a partial area of ​​the top end surface of the bottom plate 302 extends upward to form a frame-shaped boss 305, which surrounds the outside of the metal region b 304 and forms a placement groove for the electric field sensitive chip 2 between the boss and the top end surface of the bottom plate 302. Once the electric field sensitive chip 2 is placed in the placement groove, it is easy to locate the position of the electric field sensitive chip 2.

[0184] Furthermore, a plurality of through holes b are formed on the frame-shaped boss 305. When the frame-shaped boss 305 is disposed on the top end surface of the bottom plate 302, the through holes a correspond to the through holes b. Therefore, the internal end of the solder joint portion 5 can extend into the interior of the through hole b after passing through the interior of the through hole a.

[0185] Optionally, the top end surface of the built-in end is located in an area above the top end surface of the frame-shaped boss 305 , or the top end surface of the built-in end is located in the same plane as the top end surface of the frame-shaped boss 305 .

[0186] Preferably, the top end surface of each built-in end is located in the upper area of ​​the top end surface of the frame-shaped boss 305 , so as to facilitate welding of each soldering point portion 5 and each connecting lead 4 .

[0187] Preferably, the frame-shaped boss 305 is made of insulating material to prevent two adjacent solder joints 5 from being connected to each other.

[0188] Example 6

[0189] like Figure 6 As shown, this embodiment provides an electric field sensor, which differs from the above-mentioned fourth embodiment in that:

[0190] Specifically, the package cover plate 1 includes a cover plate 100, a getter 103, and an inner core 101 that penetrates the cover plate 100 and the getter 103. The inner core 101 includes an inner convex end extending vertically downward and adjacent to the electric field sensitive chip 2, and an upper end extending vertically upward and located above the cover plate 100.

[0191] Example 7

[0192] like Figure 7 As shown, this embodiment provides an electric field sensor, which differs from the above-mentioned embodiment 2 in that:

[0193] Specifically, the package cover plate 1 includes a cover plate 100, a getter 103, and an inner core 101 that penetrates the cover plate 100 and the getter 103. The inner core 101 includes an inner convex end extending vertically downward and adjacent to the electric field sensitive chip 2, and an upper end extending vertically upward and located above the cover plate 100.

[0194] In the above-mentioned embodiments 3 to 7, by adding an inner protrusion to the bottom end surface of the packaging cover, when the packaging cover is buckled onto the open end surface of the packaging tube shell, the inner protrusion and the getter will discharge part of the gas in the space, thereby reducing the gas capacity in the space, improving the gas extraction efficiency and the vacuum packaging efficiency of the electric field sensor.

[0195] The above description is merely a preferred embodiment of the present invention and is intended to be illustrative rather than restrictive of the present invention. Those skilled in the art will appreciate that many changes, modifications, and even equivalents may be made to the present invention within the spirit and scope of the claims, all of which fall within the scope of protection of the present invention.

Claims

1. A vacuum packaging method for an electric field sensor, characterized in that: The following steps are involved: Disposing a getter on the bottom end surface of the packaging cover plate; Under vacuum heating conditions, the electric field sensitive chip is fixed in the package tube shell; Electrically connecting the electric field sensitive chip to a designated solder joint portion in the package shell; Under vacuum conditions, the getter is activated, and the package cover is buckled and fixed on the open end surface of the package shell.

2. The vacuum packaging method of the electric field sensor according to claim 1, characterized in that: In the vacuum heating state, the electric field sensitive chip is fixed in the packaging tube shell, including the following steps: Placing the electric field sensitive chip in the soldering area of ​​the package shell; The interior of the eutectic furnace is preheated under vacuum for a preset time; The internal temperature of the eutectic furnace is continuously controlled at the melting temperature of the soldering medium, and the electric field sensitive chip is fixed in the soldering area by the melted soldering medium.

3. The vacuum packaging method of the electric field sensor according to claim 1, characterized in that: In the vacuum state, activating the getter and fastening and fixing the package cover to the open end surface of the package shell include the following steps: Placing the packaging cover plate with the getter attached thereto in a lower tooling, and placing the packaging tube shell in an upper tooling; Buckling the upper tooling and the lower tooling together so that the package cover is buckled onto the open end surface of the package shell and one end surface of the connecting portion contacts the package shell; The interior of the eutectic furnace is preheated under vacuum for a preset time; Under vacuum conditions, continuously controlling the internal temperature of the eutectic furnace to a getter activation temperature to activate the getter; Under vacuum conditions, the internal temperature of the eutectic furnace is continuously controlled at the melting temperature of the connection portion, and the package cover is buckled and fixed to the open end surface of the package shell through the melted connection portion.

4. The vacuum packaging method of the electric field sensor according to claim 1, characterized in that: In the vacuum state, activating the getter and fastening and fixing the package cover to the open end surface of the package shell include the following steps: Placing the packaging cover plate with the getter attached thereto in a lower tooling, and placing the packaging tube shell in an upper tooling; In a vacuum state, continuously applying current to the getter to activate the getter; Buckling the upper tooling and the lower tooling together so that the package cover is buckled onto the open end surface of the package shell and one end surface of the connecting portion contacts the package shell; The interior of the eutectic furnace is preheated under vacuum for a preset time; Under vacuum conditions, the internal temperature of the eutectic furnace is continuously controlled at the melting temperature of the connection portion, and the package cover is buckled and fixed to the open end surface of the package shell through the melted connection portion.

5. A vacuum packaging method for an electric field sensor, characterized in that: The following steps are involved: Under vacuum conditions, activating the getter on the package cover; Under vacuum heating conditions, the electric field sensitive chip is fixed in the package tube shell; Electrically connecting the electric field sensitive chip to a designated solder joint portion in the package shell; Under vacuum heating, the packaging cover is buckled and fixed on the open end surface of the packaging tube shell.

6. The vacuum packaging method of the electric field sensor according to claim 5, characterized in that: The step of activating the getter on the package cover in a vacuum state includes: In a vacuum state, continuously applying current to the getter to activate the getter; Alternatively, in a vacuum state, the internal temperature of the eutectic furnace is continuously controlled to be at a getter activation temperature to activate the getter.

7. An electric field sensor encapsulated by the vacuum encapsulation method of an electric field sensor according to any one of claims 1 to 6, characterized in that: The package cover comprises a package cover plate, a package shell, and an electric field sensitive chip. The package cover plate is fastened and fixed to the open end surface of the package shell through a melted connection portion to form a package structure for the electric field sensitive chip and provide space for placing the electric field sensitive chip. The package cover plate comprises a cover plate and a getter arranged on the cover body.

8. The electric field sensor according to claim 7, characterized in that An inner convex portion is formed on a local area of ​​the bottom end surface of the cover plate, and the getter is arranged on the bottom end surface of the inner convex portion, wherein: The inner convex portion includes a first side wall surface a and a first side wall surface b. When the packaging cover is buckled and fixed to the open end surface of the packaging tube shell, the first side wall surface a is adjacent to the inner side wall surface of the packaging tube shell, and the first side wall surface b is adjacent to the other inner side wall surface of the packaging tube shell.

9. The electric field sensor according to claim 8, characterized in that The bottom end surface of the cover plate further includes a contact area surrounding the outer side of the inner protrusion. The connecting portion is fixed on the contact area and surrounds the outer side of the inner protrusion.

10. The electric field sensor according to claim 9, characterized in that A plurality of solder joints are provided on the bottom plate of the package shell, and the electric field sensitive chip is connected to the designated solder joints via connecting leads, wherein: After each solder point portion passes through the bottom plate of the package tube shell, the top end surface of each solder point portion extends into the space to form an internal end, and the internal end is electrically connected to the electric field sensitive chip through the connecting lead, and the bottom end surface of each solder point portion is in the same plane as the bottom end surface of the package tube shell; Alternatively, after each of the solder joints penetrates the bottom plate of the packaging tube shell, the top end surface of the solder joint and the inner wall surface of the bottom plate of the packaging tube shell are in the same plane to form a built-in end, and the built-in end is electrically connected to the electric field sensitive chip through the connecting lead, and the bottom end surface of each of the solder joints is in the same plane as the bottom end surface of the packaging tube shell.

11. The electric field sensor according to claim 10, characterized in that A local area of ​​the inner wall surface of the bottom plate of the package tube shell extends upward to form a frame-shaped boss, wherein: The top end surface of the built-in end is located in an area above the top end surface of the frame-shaped boss, or the top end surface of the built-in end is located in the same plane as the top end surface of the frame-shaped boss.

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