A thermal conductivity type gas sensor package structure

Abstract

The utility model provides a kind of thermal conductivity gas sensor packaging structure, belong to gas sensor technical field.The thermal conductivity gas sensor packaging structure includes: packaging base;Upper cover body, with the packaging base sealing connection and jointly define and hold space;Thermal conductivity gas sensor, for inductive sensor film layer temperature change caused by the concentration of gas to be measured, the thermal conductivity gas sensor is arranged in the holding space and includes tester and compensator;Isolation structure, be arranged in the holding space, the isolation structure is used to isolate the tester and compensator;Wherein, the upper cover body is equipped with with the first through -hole of the isolation space of tester and communication, for into the gas to be measured.The thermal conductivity gas sensor packaging structure of the utility model is simple structure, size is smaller, and sensitivity is improved.

Description

Technical Field

[0001] This application relates to the field of gas sensor technology, and in particular to a thermally conductive gas sensor packaging structure. Background Technology

[0002] Thermal conductivity gas sensors are sensors that detect the concentration of a target gas in a gas mixture based on the difference in thermal conductivity of different gases.

[0003] To provide a reference value for thermally conductive gas sensors, they typically include a detection device and a compensation device. The compensation device has the same structure as the detection device, except that during detection, the detection device is in contact with the gas to be measured, while the compensation device is not in contact with the gas to be measured, thus providing a compensated reference value for the value detected by the detection device.

[0004] For the packaging of this type of thermal conductivity gas sensor, the existing technology usually packages the detection device and the compensation device separately. However, this packaging method requires two sets of packaging shells, which are large in structure and size. Furthermore, the independent packaging results in a certain distance between the two devices. This distance can lead to greater environmental differences between the two devices, which can cause a decrease in sensitivity due to environmental differences. Utility Model Content

[0005] One objective of this invention is to provide a thermally conductive gas sensor packaging structure that simplifies the structure, reduces the size, and improves sensitivity.

[0006] Another objective of this invention is to further improve the sealing effect.

[0007] An embodiment of this utility model provides a thermal conductivity gas sensor packaging structure, including: Packaging substrate; The upper cover is sealed to the encapsulation substrate and together defines the accommodating space; A thermally conductive gas sensor is used to sense changes in the temperature of the sensor membrane caused by the concentration of the gas to be measured. The thermally conductive gas sensor is disposed within the accommodating space and includes a testing device and a compensation device. An isolation structure is disposed within the accommodating space, the isolation structure being used to isolate the test device and the compensation device; The upper cover has at least one first through hole that communicates with the isolation space where the test device is located, for introducing the gas to be tested.

[0008] Optionally, the test device and the compensation device share a PCB board, which serves as the packaging substrate.

[0009] Optionally, the upper cover has a first cavity with a downward opening, and the first cavity is provided with a first partition, which serves as the isolation structure.

[0010] Optionally, the isolation structure includes two separate encapsulation covers, each encapsulation cover forming an encapsulation space with the PCB board to seal the test device and the compensation device respectively, and the test device has a second through hole corresponding to the encapsulation cover; The upper cover is formed by plastic sealing, and the first through hole is connected to the second through hole.

[0011] Optionally, the encapsulation substrate is a ceramic shell, the ceramic shell forming a second cavity with an upward opening, and a second partition is disposed within the second cavity, the second partition serving as the isolation structure.

[0012] Optionally, both the testing device and the compensation device are cantilever devices or membrane devices; The cantilever device includes a first base layer and a cantilever structure. A first groove is provided on the top surface of the first base layer, and the cantilever structure is suspended above the first groove. The suspended membrane device includes a second base layer and a suspended membrane structure. A second groove is provided on the bottom surface of the second base layer, and the suspended membrane structure is disposed on the top surface of the second base layer.

[0013] Optionally, both the suspended beam structure and the suspended membrane structure include a heated detection layer, which generates heat when energized to change the surface temperature of the detection structure and sense temperature changes caused by different concentrations of the gas to be measured; or Both the suspended beam structure and the suspended membrane structure include a heating layer and a detection layer that are isolated from each other. The heating layer is used to generate heat when energized to change the surface temperature of the detection structure. The detection layer is used to sense temperature changes caused by different concentrations of the gas to be tested.

[0014] Optionally, the cantilever structure includes a detection structure and a cantilever structure located around the detection structure, the cantilever structure being used to suspend the detection structure above the first groove; The first base layer is also provided with a pad, and the cantilever structure is also used to realize the electrical connection between the probe structure and the pad.

[0015] Optionally, the detection structure may also include a thermally conductive metal layer at the top.

[0016] Optionally, the thermally conductive metal layer is provided with a plurality of third through holes for stress relief.

[0017] According to one aspect of this utility model, a packaging structure for a thermally conductive gas sensor including a detection device and a compensation device is provided. An accommodating space is constructed by an upper cover and a packaging substrate. Within the accommodating space, the space for the detection device and the compensation device are isolated by an isolation structure. The upper cover has a first through-hole connecting the space where the detection device is located, allowing the gas to be measured to smoothly reach the detection device. The compensation device is located within a sealed space. This achieves the packaging of a thermally conductive gas sensor including a detection device and a compensation device. This packaging structure is simple in structure, small in size, and has a small distance between the detection device and the compensation device, thus reducing the sensitivity reduction problem caused by environmental differences.

[0018] Furthermore, the test device and compensation device of this application share a PCB board, which is used as the packaging substrate, thus further reducing the number of components and simplifying the structure. The upper cover itself is provided with a first partition, which serves as an isolation structure. Effective isolation between the test device and the compensation device can be achieved simply by sealing the upper cover to the PCB board, further simplifying the structure and installation process, which is beneficial for reducing costs and improving packaging efficiency.

[0019] Furthermore, this application provides another packaging structure in which the test device and the compensation device each have their own packaging cover, thus better isolating the two devices. The upper cover is formed using a molding process, resulting in better sealing and protection for the test device and the compensation device.

[0020] Furthermore, this application employs a cantilevered detection structure and compensation structure, which can effectively increase the contact area between the gas and the membrane region (detection structure), thereby improving the detection sensitivity. The cantilever structure can also reduce heat dissipation from the membrane region to the first substrate layer, increase the proportion of heat conduction of the gas under test in the overall heat dissipation of the device, further improve sensitivity, and also reduce power consumption.

[0021] Furthermore, the detection structure of this application also includes a thermally conductive metal layer at the top. The thermally conductive metal layer has a high thermal conductivity, which can transfer more heat from the gas to be measured to the test layer, thereby giving the sensor better sensitivity. Attached Figure Description

[0022] Figure 1 This is a cross-sectional view of the packaging structure of the thermally conductive gas sensor according to Embodiment 1 of the present invention. Figure 2 This is a top view of the upper cover of the thermal conductivity gas sensor packaging structure according to Embodiment 1 of the present invention; Figure 3 This is a schematic diagram of the thermal conductivity gas sensor packaging structure according to Embodiment 2 of the present invention; Figure 4This is a schematic diagram of the thermal conductivity gas sensor packaging structure according to Embodiment 3 of the present invention; Figure 5 This is a schematic diagram of the thermal conductivity gas sensor packaging structure (top cover hidden) according to Embodiment 3 of this utility model; Figure 6 This is a schematic diagram of the test device based on a thermal conductivity gas sensor packaging structure according to an embodiment of the present invention; Figure 7 According to Figure 6 A cross-sectional view of the test device in the embodiment; Figure 8 This is a schematic diagram of the test device based on the thermal conductivity gas sensor packaging structure according to another embodiment of the present invention; Figure label: The thermally conductive gas sensor encapsulation structure includes: 100, encapsulation substrate 10, upper cover 20, thermally conductive gas sensor 30, test device 31, compensation device 32, isolation structure 40, first through hole 201, PCB board 11, first partition 21, encapsulation cover 41, second through hole 411, ceramic shell 12, second partition 121, first base layer 51, first groove 511, detection structure 52, first support layer 521, heating layer 522, first protective layer 523, test layer 524, second protective layer 525, first cantilever beam 53, second cantilever beam 54, second support layer 501, first conductive layer 502, third protective layer 503, fourth protective layer 504, thermally conductive metal layer 526, third through hole 527, and solder pad 512. Detailed Implementation

[0023] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, it should be noted that, for ease of description, only the parts relevant to this application are shown in the accompanying drawings, not the entire structure. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this application.

[0024] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments.

[0025] Furthermore, to better illustrate this application, numerous specific details are provided in the following detailed description. Those skilled in the art should understand that this application can be implemented without certain specific details. In some instances, methods, means, components, and circuits well known to those skilled in the art have not been described in detail in order to highlight the spirit of this disclosure.

[0026] It should be understood that the term "and / or" in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this article indicates that the preceding and following related objects have an "or" relationship.

[0027] In this application's embodiments, "multiple" refers to two or more. The descriptions of "first," "second," etc., appearing in this application's embodiments are merely illustrative and for distinguishing the described objects; they have no order and do not indicate a specific limitation on the number in this application's embodiments, nor do they constitute any limitation on the embodiments of this application.

[0028] Example 1 Figure 1 This is a cross-sectional view of the packaging structure 100 of the thermally conductive gas sensor 30 according to Embodiment 1 of the present invention. Figure 2 This is a top view of the upper cover 20 of the thermal conductivity gas sensor 30 packaging structure 100 according to Embodiment 1 of this utility model. Figure 1 As shown, the thermal conductivity gas sensor 30 packaging structure 100 in this embodiment includes a packaging substrate 10, a top cover 20, a thermal conductivity gas sensor 30, and an isolation structure 40. The top cover 20 is sealed to the packaging substrate 10 and together defines an accommodating space. The thermal conductivity gas sensor 30 is used to sense the temperature change of the sensor film layer (i.e., the surface of the sensor sensing area) caused by the concentration of the gas to be measured. The thermal conductivity gas sensor 30 is disposed within the accommodating space and includes a test device 31 and a compensation device 32. The isolation structure 40 is disposed within the accommodating space and is used to isolate the test device 31 and the compensation device 32. The top cover 20 has at least a first through hole 201 communicating with the isolation space where the test device 31 is located, for introducing the gas to be measured. In this embodiment, the test device 31 and the compensation device 32 share a PCB board 11, which serves as the packaging substrate 10. Figure 2 As shown, the upper cover 20 has a first cavity with an opening facing downwards, and a first partition 21 is provided in the first cavity. The first partition 21 serves as an isolation structure 40. The material of the upper cover 20 can be plastic or metal. The first partition 21 and the upper cover 20 are an integral structure. In other embodiments, the first partition 21 can also be assembled to the upper cover 20, which is not limited here.

[0029] In this embodiment, the test device 31 and the compensation device 32 have the same structure. The test device 31 is in direct contact with the gas to be tested, while the compensation device 32 is sealed. The value measured by the compensation device 32 can be used as a compensation reference value for the test device 31. Here, the test device 31 and the compensation device 32 are small devices integrated on a PCB board, which can detect the concentration of the gas to be tested in a mixed gas based on the difference in thermal conductivity of different gases.

[0030] This embodiment provides a packaging structure for a thermally conductive gas sensor 30 including a detection device and a compensation device 32. The upper cover 20 and the packaging substrate 10 jointly construct an accommodating space. Within the accommodating space, the space for the detection device and the compensation device 32 is isolated by an isolation structure 40. The upper cover 20 has a first through hole 201 connecting the space where the detection device is located, allowing the gas to be measured to reach the detection device smoothly. The compensation device 32 is located in a sealed space, thus realizing the packaging of the thermally conductive gas sensor 30 including the detection device and the compensation device 32. This packaging structure is simple in structure and small in size, and the distance between the detection device and the compensation device 32 is small, thus reducing the problem of sensitivity reduction caused by environmental differences.

[0031] Furthermore, in this embodiment, the test device 31 and the compensation device 32 share the same PCB board 11, which serves as the packaging substrate 10. This further reduces the number of components and simplifies the structure. The upper cover 20 itself is provided with a first partition 21, which serves as an isolation structure 40. Effective isolation between the test device 31 and the compensation device 32 can be achieved simply by sealing the upper cover 20 to the PCB board 11. This further simplifies the structure and installation process, and helps to reduce costs and improve packaging efficiency.

[0032] Example 2 Figure 3 This is a schematic diagram of the packaging structure 100 of the thermally conductive gas sensor 30 according to Embodiment 2 of this utility model. Figure 3 As shown, this embodiment differs from the upper cover 20 and isolation structure 40 of Embodiment 1. In this embodiment, the isolation structure 40 includes two separate encapsulation covers 41. Each encapsulation cover 41 forms an encapsulation space with the PCB board 11, and is used to seal the test device 31 and the compensation device 32 respectively. The test device 31 has a second through hole 411 corresponding to the encapsulation cover 41. The upper cover 20 is formed by plastic encapsulation, and the first through hole 201 communicates with the second through hole 411.

[0033] This embodiment provides another packaging structure in which the test device 31 and the compensation device 32 each have their own packaging cover 41, thus better isolating the two devices. The upper cover 20 is formed by plastic encapsulation, which provides better sealing and better protection for the test device 31 and the compensation device 32.

[0034] Example 3 Figure 4 This is a schematic diagram of the thermal conductivity gas sensor 30 packaging structure 100 according to Embodiment 3 of this utility model. Figure 5 This is a schematic diagram of the packaging structure 100 (top cover 20 omitted) of the thermally conductive gas sensor 30 according to Embodiment 3 of this utility model. Figure 5 As shown, in this embodiment, the encapsulation substrate 10 is a ceramic shell 12, the ceramic shell 12 forms a second cavity with an upward opening, and a second partition 121 is provided in the second cavity, the second partition 121 is used as an isolation structure 40.

[0035] Figure 6 This is a schematic diagram of the test device 31 of the thermal conductivity gas sensor 30 packaging structure 100 according to an embodiment of the present invention. Figure 7 According to Figure 6 A cross-sectional view of the test device 31 in the embodiment. Since the compensation device 32 has the same structure as the test device 31, therefore... Figure 6 , Figure 7 and Figure 8 This is also a structural schematic diagram of the compensation device 32. Figure 6 A fifth membrane layer is hidden within it. For example... Figure 6As shown, both the test device 31 and the compensation device 32 are cantilever devices. The cantilever device includes a first substrate 51 and a cantilever structure. The first substrate 51 is made of a silicon substrate, and a first groove 511 is provided on the top surface of the first substrate 51. The cantilever structure is suspended above the first groove 511. In this embodiment, the cantilever structure includes a detection structure 52 and a cantilever structure located around the detection structure 52. The cantilever structure is used to suspend the detection structure 52 above the first groove 511. A pad 512 is also provided at the first substrate 51. The cantilever structure is also used to achieve an electrical connection between the detection structure 52 and the pad 512. The detection structure 52 includes a heating layer 522 and a test layer 524 that are isolated from each other. The heating layer 522 is used to generate heat when energized to change the surface temperature of the detection structure 52. The test layer 524 is used to sense temperature changes caused by different concentrations of the test gas. In this embodiment, both the heating layer 522 and the test layer 524 are arranged in a serpentine pattern, and the routing directions are perpendicular to each other. That is to say, the heating layer 522 and the test layer 524 are linear. The routing directions being perpendicular to each other can be understood as follows: assuming that the heating layer 522 winds back and forth in the first horizontal direction, the test layer 524 winds back and forth in the second horizontal direction, which is perpendicular to the first horizontal direction.

[0036] During testing, the heating layer 522 is energized and generates heat. When gases with different thermal conductivity are present at the sensor, the temperature of the surface of the detection structure 52 drops. At this time, the resistance of the test layer 524 decreases accordingly. The corresponding voltage or current change can be obtained through the test circuit connected to the test layer 524 at the back end, thereby realizing the concentration detection of the gas to be tested.

[0037] This embodiment employs a cantilevered detection structure 52 and a compensation structure, which can effectively increase the contact area between the gas and the membrane region (detection structure 52), thereby improving the detection sensitivity. The cantilever structure can also reduce the heat dissipation from the membrane region to the first substrate layer 51, increase the proportion of heat conduction of the gas under test in the overall heat dissipation of the device, further improve the sensitivity, and also reduce power consumption.

[0038] Furthermore, the detection structure 52, from bottom to top, includes a first support layer 521, a heating layer 522, a first protective layer 523, a test layer 524, and a second protective layer 525. The cantilever structure includes two first cantilever beams 53 and two second cantilever beams 54. The two first cantilever beams 53 are connected to both ends of the heating layer 522, and the two second cantilever beams 54 are connected to both ends of the test layer 524. The first cantilever beam 53 includes a second support layer 501, a first conductive layer 502, a third protective layer 503, and a fourth protective layer 504. The second cantilever beam 54 includes a third support layer, a second conductive layer, a fifth protective layer, and a sixth protective layer. The first conductive layer 502 is connected to the heating layer 522, and the second conductive layer is connected to the test layer 524.

[0039] In this embodiment, the first support layer 521, the second support layer 501, and the third support layer are formed by processing a first film layer, the material of which is one or both of silicon oxide and silicon nitride. The heating electrode and the first conductive layer 502 are formed by processing a second film layer, the material of which is platinum or tungsten. The first protective layer 523, the third protective layer 503, and the fifth protective layer are formed by processing a third film layer, the material of which is one or both of silicon oxide and silicon nitride. The test layer 524 and the second conductive layer are formed by processing a fourth film layer, the material of which is platinum or tungsten. The second protective layer 525, the fourth protective layer 504, and the sixth protective layer are formed by processing a fifth film layer, the material of which is one or both of silicon oxide and silicon nitride.

[0040] In another embodiment, the cantilever device may include a heating detection layer, which realizes both the heating function and the sensing output function. That is, the difference between this embodiment and the above embodiment is that the detection layer is no longer provided, and the heating layer in the above embodiment realizes both the heating function and the sensing function. Other structures are the same as those in the above embodiment, and will not be described again here.

[0041] Figure 8 This is a schematic diagram of the test device 31 of the thermal conductivity gas sensor 30 packaging structure 100 according to another embodiment of the present invention. In another embodiment, as... Figure 8 As shown, the detection structure 52 also includes a thermally conductive metal layer 526 at the top. The thermally conductive metal layer 526 has several third through holes 527 for stress relief. In this embodiment, the cantilever device includes a heated detection layer, so there are only two pads 512 on the first base layer 51. Of course, for the above embodiment including a heating layer 522 and a test layer 524, a thermally conductive metal layer 526 can also be provided at the top.

[0042] The thermally conductive metal layer 526 here is made of one or more of platinum, tungsten, chromium, and gold. The thermally conductive metal layer 526 has a high thermal conductivity, enabling it to transfer more heat from the gas being measured to the test layer 524, thus improving the sensor's sensitivity. Furthermore, the presence of several third through-holes 527 prevents the thermally conductive metal layer 526 from warping due to stress.

[0043] In one embodiment not shown, the suspended membrane device includes a second base layer and a suspended membrane structure. A second groove is provided at the bottom surface of the second base layer, and the suspended membrane structure is disposed at the top surface of the second base layer. The structure of the suspended membrane structure is similar to that of the suspended beam structure, and will not be described in detail here.

[0044] The embodiments described above are merely illustrative of several implementations of this utility model, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.

Claims

1. A thermal conductivity gas sensor packaging structure, characterized in that, include: Packaging substrate; The upper cover is sealed to the encapsulation substrate and together defines the accommodating space; A thermally conductive gas sensor is used to sense changes in the temperature of the sensor membrane caused by the concentration of the gas to be measured. The thermally conductive gas sensor is disposed within the accommodating space and includes a testing device and a compensation device. An isolation structure is disposed within the accommodating space, the isolation structure being used to isolate the test device and the compensation device; The upper cover has at least one first through hole that communicates with the isolation space where the test device is located, for introducing the gas to be tested.

2. The thermal conductivity gas sensor packaging structure according to claim 1, characterized in that, The test device and the compensation device share a PCB board, which serves as the packaging substrate.

3. The thermal conductivity gas sensor packaging structure according to claim 2, characterized in that, The upper cover has a first cavity with an opening facing downwards, and a first partition is provided in the first cavity, which serves as the isolation structure.

4. The thermal conductivity gas sensor packaging structure according to claim 2, characterized in that, The isolation structure includes two separate encapsulation covers, each encapsulation cover forming an encapsulation space with the PCB board to seal the test device and the compensation device respectively. The test device has a second through hole corresponding to the encapsulation cover. The upper cover is formed by plastic sealing, and the first through hole is connected to the second through hole.

5. The thermal conductivity gas sensor packaging structure according to claim 1, characterized in that, The encapsulation substrate is a ceramic shell, which forms a second cavity with an upward opening. A second partition is disposed within the second cavity, and the second partition serves as the isolation structure.

6. The thermal conductivity gas sensor packaging structure according to any one of claims 1-5, characterized in that, Both the testing device and the compensation device are cantilever devices or membrane devices; The cantilever device includes a first base layer and a cantilever structure. A first groove is provided on the top surface of the first base layer, and the cantilever structure is suspended above the first groove. The suspended membrane device includes a second base layer and a suspended membrane structure. A second groove is provided on the bottom surface of the second base layer, and the suspended membrane structure is disposed on the top surface of the second base layer.

7. The thermal conductivity gas sensor packaging structure according to claim 6, characterized in that, Both the suspended beam structure and the suspended membrane structure include a heated detection layer. The suspended beam structure includes a detection structure. The heated detection layer generates heat when energized to change the surface temperature of the detection structure and senses temperature changes caused by different concentrations of the gas to be measured; or Both the suspended beam structure and the suspended membrane structure include a heating layer and a test layer that are isolated from each other. The heating layer is used to generate heat when energized to change the surface temperature of the detection structure. The test layer is used to sense temperature changes caused by different concentrations of the gas to be tested.

8. The thermal conductivity gas sensor packaging structure according to claim 6, characterized in that, The cantilever structure includes a detection structure and a cantilever structure located around the detection structure, the cantilever structure being used to suspend the detection structure above the first groove; The first base layer is also provided with a pad, and the cantilever structure is also used to realize the electrical connection between the probe structure and the pad.

9. The thermal conductivity gas sensor packaging structure according to claim 8, characterized in that, The detection structure also includes a thermally conductive metal layer at the top.

10. The thermal conductivity gas sensor packaging structure according to claim 9, characterized in that, The thermally conductive metal layer is provided with several third through holes for stress relief.

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