Packaging assembly of pressure sensor

Abstract

The invention discloses a packaging assembly of a pressure sensor. The packaging assembly comprises a packaging shell. The packaging shell is provided with at least two cavities which are not communicated with each other, the cavities comprise a first cavity and a second cavity, a pressure chip is fixedly arranged in the first cavity, and a second chip is fixedly arranged in the second cavity; the first cavity is provided with a first mounting port, the pressure chip is accommodated in the first cavity through the first mounting port, the second cavity is provided with a second mounting port, and the second chip is accommodated in the second cavity through the second mounting port; an air hole is formed in the bottom or the side wall of the first cavity and corresponds to a detection opening of the pressure chip. The special packaging structure is adopted, corrosion resistance is achieved, reliability is good, and detection is convenient.

Description

Technical Field

[0001] The present invention relates to the field of pressure sensors, and particularly to a packaging component of a pressure sensor. Background Art

[0002] With the development needs of social intelligence, the application fields of pressure sensors are becoming wider and wider, and the demand is increasing; for existing vehicle pressure sensors, due to the complex pressure environment in automobiles, the measured media often have corrosiveness and conductivity. Corrosive media are likely to invade the inside of the gel, causing damage to the circuit part, especially the IC chip is extremely vulnerable to damage. If multiple chips are packaged, it is impossible to determine which chip has problems, which also greatly reduces the long-term reliability of the pressure sensor.

[0003] Most of the existing pressure sensors on the market are fixed and electrically connected by means of solder paste welding. In this way, the pressure sensor inevitably has to go through high temperatures, which will cause changes in the internal stress of the packaging material, resulting in performance drift of the pressure sensor, especially having a greater impact on the micro-pressure pressure sensor that is more sensitive to packaging.

[0004] At the same time, the existing pressure sensors on the market cannot be compatible with the packaging of differential pressure chips and absolute pressure chips.

[0005] Therefore, in combination with the above existing technical problems, it is necessary to propose a new technical solution. Summary of the Invention

[0006] In order to solve at least one of the technical problems existing in the prior art, the present invention proposes a packaging component of a pressure sensor with corrosion resistance, good reliability performance and convenient detection. The specific technical solutions are as follows:

[0007] The present invention provides a packaging component of a pressure sensor, including a packaging housing;

[0008] At least a first cavity and a second cavity that are not connected to each other are provided on the packaging housing. A pressure chip is fixedly arranged in the first cavity, and a second chip is fixedly arranged in the second cavity;

[0009] The first cavity is provided with a first installation opening, and the pressure chip is placed in the first cavity through the first installation opening. The second cavity is provided with a second installation opening, and the second chip is placed in the second cavity through the second installation opening;

[0010] An air hole is provided at the bottom or side wall of the first cavity, and the air hole corresponds to the detection port of the pressure chip;

[0011] A first pad is provided at the bottom or side wall of the first cavity, and the pressure chip is electrically connected to the first pad by means of flip-chip contact or wire bonding.

[0012] As a preferred embodiment of the present invention, a sealing ring is provided on the surface of the encapsulation housing, and the air hole is located within the sealing ring.

[0013] As a preferred embodiment of the present invention, the second chip is an IC chip;

[0014] The encapsulation housing is provided with application terminal pins, and both the pressure chip and the second chip are electrically connected to the application terminal pins directly or indirectly through the pads within the encapsulation housing.

[0015] As a preferred embodiment of the present invention, a first circuit adapter board is further provided within the first cavity, and first pads are provided at the bottom or sidewall of the first cavity. The first circuit adapter board is electrically connected to the first pads, and the pressure chip is electrically connected to the first circuit adapter board by means of flip-chip contact electrical connection or wire bonding electrical connection.

[0016] As a preferred embodiment of the present invention, a second circuit adapter board is further provided within the second cavity, and second pads are provided at the bottom or sidewall of the second cavity. The second circuit adapter board is electrically connected to the second pads, and the second chip is electrically connected to the second circuit adapter board.

[0017] As a preferred embodiment of the present invention, the encapsulation housing is further provided with detection terminal pins. One end of the detection terminal pins extends into the first cavity or extends into the first cavity through a circuit and is electrically connected to the pressure chip, and the other end of the detection terminal pins extends out of the encapsulation housing.

[0018] As a preferred embodiment of the present invention, after at least the pressure chip is installed within the first cavity, according to different application requirements, a first potting structure can be filled in the remaining space within the first cavity, or a first protective cover can be covered on the first mounting opening, or neither potting nor covering the first protective cover is performed. Specifically, after at least the pressure chip is installed within the first cavity, a first potting structure is filled in the remaining space within the first cavity; or after at least the pressure chip is installed within the first cavity, a first protective cover is covered on the first mounting opening of the first cavity; or after the pressure chip is installed within the first cavity, no potting is performed within the first cavity and the first mounting opening is not covered with the first protective cover.

[0019] More preferably, the first potting structure is soft jelly silicone.

[0020] As a preferred embodiment of the present invention, after at least the second chip is installed within the second cavity, a second potting structure is filled in the remaining space within the second cavity; or after at least the second chip is installed within the second cavity, a second protective cover is covered on the second mounting opening; or after at least the second chip is installed within the second cavity, a second potting structure is filled in the remaining space within the second cavity and a second protective cover is covered on the second mounting opening.

[0021] More preferably, the second potting structure is hard epoxy resin or polyurethane resin.

[0022] As a preferred embodiment of the present invention, an annular sealing structure is provided between the first circuit adapter board and the first cavity, and the annular sealing structure is wound around the periphery of the air hole.

[0023] As a preferred embodiment of the present invention, the pressure chip is an absolute pressure chip pressed from the back, and a first protective cover can be covered on the first mounting opening.

[0024] As a preferred embodiment of the present invention, the encapsulation housing is further provided with application end pins, and both the pressure chip and the second chip are electrically connected to the application end pins indirectly or directly.

[0025] As a preferred embodiment of the present invention, a sealing groove is formed on the inner wall of the first cavity, and the air hole is accommodated in the sealing groove.

[0026] As a preferred embodiment of the present invention, a through hole for the measured medium is formed at the bottom of the second cavity, and the back surface of the IC chip is configured to be able to contact the measured medium to sense the temperature of the measured medium.

[0027] Compared with the prior art, the present invention has at least the following beneficial effects:

[0028] This patent uses multiple cavities for separate encapsulation. The pressure chip and the second chip are separately encapsulated in two cavities. The IC cavity is protected by a hard glue with good reliability and a second protective cover.

[0029] The encapsulation structure is flexible and changeable. It can be used for the encapsulation of differential pressure chips and gauge pressure chips, and can also be used for the encapsulation of absolute pressure chips. At the same time, it is compatible with the encapsulation and application of differential pressure, gauge pressure and absolute pressure chips.

[0030] The application end pins of the encapsulation can be connected by laser welding or wire bonding electrical connection, without the thermal process of reflow soldering, which will not affect the performance of the pressure chip, especially the micro differential pressure chip, and increases the reliability of the product.

[0031] A sealing ring is provided for sealing, which facilitates the assembly and sealing of the product and the module housing. It can not only ensure that the pressure of the measured medium will not leak, but also protect the circuit structure in the cavity.

[0032] Detection end pins are provided to directly read the signal of the pressure chip, and the pressure chip can be directly detected and checked, and it can be intuitively detected whether there is a problem with the pressure chip.

[0033] The first potting structure and the second potting structure are provided to effectively protect the circuit structure of the chip.

[0034] The additional aspects and advantages of the present invention will be partially given in the following description, partially become obvious from the following description, or be understood through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] To more clearly illustrate the technical solutions of the present invention, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0036] Figure 1 is a three-dimensional structural schematic diagram of the encapsulation housing described in the present invention;

[0037] Figure 2 is a top-view structural schematic diagram of the encapsulation housing described in the present invention;

[0038] Figure 3 is a bottom-view structural schematic diagram of the encapsulation housing described in the present invention;

[0039] Figure 4 is a three-dimensional sectional structural schematic diagram of the encapsulation housing described in the present invention;

[0040] Figure 5 is a three-dimensional sectional structural schematic diagram of the encapsulation assembly of the pressure sensor described in the present invention.

[0041] Wherein, 1 - encapsulation housing, 3 - pressure chip, 4 - second chip, 5 - first circuit transfer board, 6 - second circuit transfer board, 11 - first cavity, 111 - first mounting opening, 112 - air hole, 113 - first pad, 115 - first protective cover, 116 - sealing groove, 12 - second cavity, 121 - second mounting opening, 122 - through hole, 123 - second pad, 125 - second protective cover, 13 - sealing ring, 71 - application end pin, 72 - detection end pin. Specific Embodiments

[0042] The following will describe in detail the embodiments of the present invention, and clarify and completely describe the technical solutions of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0043] Please refer to Figures 1-5 , as Figures 1-5 shown, the present invention provides an encapsulation assembly for a pressure sensor, including an encapsulation housing 1;

[0044] At least non-communicating first cavity 11 and second cavity 12 are opened on the encapsulation housing 1. A pressure chip 3 is fixedly arranged in the first cavity 11, and a second chip 4 is fixedly arranged in the second cavity 12;

[0045] The first cavity 11 is provided with a first mounting opening 111, and the pressure chip 3 is received in the first cavity 11 through the first mounting opening 111. The second cavity 12 is provided with a second mounting opening 121, and the second chip 4 is received in the second cavity 12 through the second mounting opening 121;

[0046] An air hole 112 is provided in the bottom or side wall of the first cavity 11, and the air hole 112 corresponds to the detection port of the pressure chip 3;

[0047] A first pad 113 is provided on the bottom or side wall of the first cavity 11, and the pressure chip 3 is electrically connected to the first pad 113 by means of flip-chip contact or wire bonding.

[0048] This patent uses multiple cavities for separate encapsulation. The pressure chip and the second chip are separately encapsulated in two cavities. The IC cavity is protected by a hard glue with good reliability and a second protective cover.

[0049] In the example, the encapsulation housing 1 is a plastic housing. In the example, the pressure chip 3 is a MEMS pressure sensor chip.

[0050] Preferably, the second chip 4 is an IC chip, but this patent is not limited thereto, and it can also be other types of chips. In the example, the second chip 4 is an IC chip, and a through hole 122 for the measured medium is provided in the bottom or side wall of the second cavity 12, so that the back surface of the IC chip can directly sense the temperature of the measured medium, and the pressure measurement after IC calibration is more accurate. The through hole (122) is provided at an appropriate position on the bottom of the second cavity. Further preferably, the air hole 112 and the through hole 122 are provided on the same surface of the encapsulation housing 1. In the example, a second protective cover 125 is covered on the second mounting opening 121. In the example, the air hole 112 is provided in the bottom of the second cavity (12).

[0051] Preferably, the first mounting opening 111 and the second mounting opening 121 are provided on the same surface of the encapsulation housing 1.

[0052] In a preferred embodiment, a sealing ring 13 is provided on the surface of the encapsulation housing 1, and the air hole 112 is located within the sealing ring 13. In the example, both the air hole 112 and the through hole 122 are located within the sealing ring 13. In the example, the sealing ring 13 is integrally connected to the encapsulation housing 1, but this patent is not limited thereto.

[0053] Sealing is provided by the sealing ring, which facilitates the assembly and sealing of the product with the module housing, can not only ensure that the pressure of the measured medium does not leak, but also protect the circuit structure within the cavity.

[0054] One example is that the pressure chip 3 is an absolute pressure chip, including a back-pressure absolute pressure chip and a front-pressure absolute pressure chip. The pressure-receiving surface of the absolute pressure chip faces the inner wall of one side of the first cavity 11 where air holes are provided. In a specific example, the pressure chip 3 is a back-pressure absolute pressure chip independently developed by our company. For details of the back-pressure absolute pressure chip, refer to the patent ZL202223083619.2.

[0055] One example is that the pressure chip 3 is a differential pressure chip.

[0056] In a preferred embodiment, a first pad 113 is provided at the bottom or side wall of the first cavity 11, and the pressure chip 3 is electrically connected to the first pad 113 by flip-chip contact or wire bonding.

[0057] The flip-chip contact or wire bonding of the pressure chip will not affect the performance of the pressure chip and improves the reliability of the product.

[0058] Further preferably, a first circuit adapter board 5 is also provided in the first cavity 11. A first pad 113 is provided at the bottom or side wall of the first cavity 11. The first circuit adapter board 5 is electrically connected to the first pad 113, and the pressure chip 3 is electrically connected to the first circuit adapter board 5 by flip-chip contact or wire bonding. In the example, the first circuit adapter board 5 is a MEMS circuit adapter board. In the example, the first pad 113 is provided at the bottom of the first cavity 11. Of course, this patent is not limited thereto. In the example, the first circuit adapter board 5 is fixedly provided in the first cavity 11.

[0059] Specifically, the first circuit adapter board 5 is glued to the bottom of the first cavity 11. The first circuit adapter board 5 is electrically connected to the first pad 113 in the first cavity 11 by gold wire bonding. The pressure chip 3 is mounted on the first circuit adapter board 5. Of course, the pressure chip 3 can also be glued to the first circuit adapter board 5. Specifically, the pressure chip 3 is electrically connected to the first circuit adapter board 5 by flip-chip contact or wire bonding using gold wire bonding. In the example, the first circuit adapter board 5 and the first pad 113 in the first cavity 11 can be electrically connected by reflow soldering paste welding gold wire bonding, or can also be electrically connected by flip-chip contact or wire bonding.

[0060] Further preferably, the first cavity 11 further includes a first potting structure (not shown in the figure). After at least installing the pressure chip in the first cavity 11, the remaining space in the first cavity is filled with the first potting structure. Or another preferred option is that after at least installing the pressure chip in the first cavity 11, a first protective cover 115 is covered on the first mounting opening 111 of the first cavity 11. Or another preferred option is that after at least installing the pressure chip in the first cavity 11, neither the first cavity is potted nor the first protective cover 115 is covered on the first mounting opening 111. In the example, the first circuit adapter board 5 is fixedly arranged and electrically connected in the first cavity 11, and then after fixedly arranging and electrically connecting the pressure chip 3, the first potting structure is filled in the remaining space of the first cavity 11, and the first protective cover 115 is not covered on the first mounting opening 111. In the example, the first potting structure is soft jelly silicone.

[0061] In one case, if the pressure chip 3 is an absolute pressure chip, after setting the first potting structure, the first protective cover 115 is covered on the first mounting opening 111. In one case, if the pressure chip 3 is a differential pressure chip, after setting the first potting structure, the first protective cover may or may not be covered on the first mounting opening 111. Of course, the first potting structure may not be filled in the first cavity. After the pressure chip is installed, the first protective cover may or may not be covered on the first mounting opening 111. The encapsulation structure is flexible and changeable, and can perform the encapsulation of differential pressure chips and gauge pressure chips, and can also perform the encapsulation of absolute pressure chips. At the same time, it is compatible with the encapsulation and application of differential pressure, gauge pressure and absolute pressure chips.

[0062] In a preferred embodiment, a second pad 123 is provided at the bottom or side wall of the second cavity 12, and the second chip 4 is electrically connected to the second pad 123.

[0063] Further preferably, a second circuit adapter board 6 is further provided in the second cavity 12. A second pad 123 is provided at the bottom or side wall of the second cavity 12. The second circuit adapter board 6 is electrically connected to the second pad 123, and the second chip 4 is electrically connected to the second circuit adapter board 6. In the example, the second pad 123 is provided at the bottom of the second cavity 12. Of course, this patent is not limited to this. In the example, the second circuit adapter board 6 is fixedly arranged in the second cavity 12.

[0064] Specifically, the second circuit adapter board 6 is adhesively mounted at the bottom of the second cavity 12. The second circuit adapter board 6 is electrically connected to the second pad 123 in the second cavity 12 by wire bonding with gold wires. The second chip 4 is mounted on the second circuit adapter board 6. In the example, the second circuit adapter board 6 and the second pad 123 in the second cavity 12 can be electrically connected by wire bonding with reflow soldering paste, or can be electrically connected by flip-chip contact or wire bonding. In the example, the second chip 4 and the second circuit adapter board 6 can be electrically connected by wire bonding with reflow soldering paste, or can be electrically connected by flip-chip contact or wire bonding.

[0065] Further preferably, a second potting structure (not shown in the figure) is further included in the second cavity 12. After at least the second chip is installed in the second cavity 12, the remaining space in the second cavity 12 is filled with the second potting structure. Or another preference is that after at least the second chip is installed in the second cavity 12, the second protective cover 125 is covered on the second mounting opening 121. Or another preference is that after at least the second chip is installed in the second cavity 12, the remaining space in the second cavity 12 is filled with the second potting structure, and the second protective cover 125 is covered on the second mounting opening 121. In the example, the second circuit adapter board 6 is fixedly arranged and electrically connected in the second cavity 12, and then the second chip 4 is fixedly arranged and electrically connected. Then, the second potting structure is filled in the second cavity 12, and then the second protective cover 125 is covered on the second mounting opening 121. In the example, the second potting structure is a rigid epoxy resin or polyurethane resin.

[0066] The first potting structure and the second potting structure are provided to effectively protect the circuit structure of the chip.

[0067] In a preferred embodiment, the packaging housing 1 is further provided with application end pins 71. The pressure chip 3 and the second chip 4 are directly or indirectly electrically connected to the application end pins 71. In the example, one end of the application end pin 71 extends into the second cavity 12 or extends into the first cavity 11 through a circuit. The pressure chip 3 and the second chip 4 are electrically connected to one end of the application end pin 71 through a circuit. The other end of the application end pin 71 extends out of the packaging housing 1. The application end pins of the packaging of this patent can be connected by laser welding or wire bonding electrical connection, without the thermal process of reflow soldering, and will not affect the performance of the pressure chip, especially the micro differential pressure chip, increasing the reliability of the product.

[0068] Further preferably, a detection end pin 72 is further included. One end of the detection end pin 72 extends into the first cavity 11 or extends into the first cavity 11 through a circuit and is electrically connected to the first pad 113. The first pad 113 is then electrically connected to the pressure chip 3. The other end of the detection end pin 72 extends out of the packaging housing 1.

[0069] Set a detection terminal pin to directly read the signal of the pressure chip, so as to directly detect and troubleshoot the pressure chip, and can intuitively detect whether there is a problem with the pressure chip.

[0070] In the example, the application terminal pin 71 and the detection terminal pin 72 are symmetrically arranged on both side surfaces of the package housing 1.

[0071] In a preferred embodiment, an annular sealing structure is provided between the first circuit adapter board 5 and the first cavity 11, and the annular sealing structure is wound around the periphery of the air hole. In the example, the annular sealing structure is an annular seal of glue or solder paste between the first circuit adapter board 5 and the bottom of the first cavity 11 to protect the internal circuit structure in the first cavity from being affected by the external environment of the air hole. Further preferably, a sealing groove 116 is provided on the inner wall of the first cavity 11, and the annular sealing structure is accommodated in the sealing groove 116.

[0072] It should be noted that, without conflict, the above-mentioned embodiments or features in the embodiments in this article can be combined with each other arbitrarily.

[0073] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "example", "specific example" or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine the different embodiments or examples described in this specification.

[0074] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention. Any reference signs in the claims should not be regarded as limiting the claims involved.

Claims

1. A packaging assembly of a pressure sensor, characterized in that: It comprises a packaging shell (1); The packaging shell (1) is provided with at least a first cavity (11) and a second cavity (12) which are not connected to each other, a pressure chip (3) is fixedly arranged in the first cavity (11), and a second chip (4) is fixedly arranged in the second cavity (12); The first cavity (11) is provided with a first mounting port (111), and the pressure chip (3) is accommodated in the first cavity (11) through the first mounting port (111); the second cavity (12) is provided with a second mounting port (121), and the second chip (4) is accommodated in the second cavity (12) through the second mounting port (121); The bottom or side wall of the first cavity (11) is provided with an air hole (112), and the air hole (112) corresponds to the detection port of the pressure chip (3); A first solder pad (113) is provided at the bottom or side wall of the first cavity (11), and the pressure chip (3) and the first solder pad (113) are electrically connected by flip-chip contact or wire bonding.

2. The packaging assembly of the pressure sensor according to claim 1, characterized in that: A sealing ring (13) is provided on the surface of the packaging shell (1), and the air hole (112) is located inside the sealing ring (13).

3. The packaging assembly of the pressure sensor according to claim 1, characterized in that: The second chip (4) is an IC chip; The packaging shell (1) is provided with an application end pin (71), and the pressure chip (3) and the second chip (4) are both directly or indirectly electrically connected to the application end pin (71) via a solder pad in the packaging shell.

4. The packaging assembly of the pressure sensor according to claim 1, characterized in that: A first circuit adapter board (5) is also provided in the first cavity (11), a first solder pad (113) is provided at the bottom or side wall of the first cavity (11), the first circuit adapter board (5) is electrically connected to the first solder pad (113), and the pressure chip (3) and the first circuit adapter board (5) are electrically connected by flip-chip contact or wire bonding; and / or A second circuit adapter board (6) is also provided in the second cavity (12); a second solder pad (123) is provided at the bottom or side wall of the second cavity (12); the second circuit adapter board (6) is electrically connected to the second solder pad (123); and the second chip (4) is electrically connected to the second circuit adapter board (6).

5. The packaging assembly of the pressure sensor according to claim 1 or 3, characterized in that: The packaging shell (1) is also provided with a detection end pin (72), one end of the detection end pin (72) extends into the first cavity (11) or extends into the first cavity (11) through a circuit and is electrically connected to the pressure chip (3), and the other end of the detection end pin (72) extends out of the packaging shell (1).

6. The packaging assembly of the pressure sensor according to claim 1 or 4, characterized in that: After at least the pressure chip is installed in the first cavity (11), the first glue filling structure is filled in the remaining space in the first cavity; or after at least the pressure chip is installed in the first cavity (11), the first installation opening (111) of the first cavity (11) is covered with a first protective cover (115); or after the pressure chip is installed in the first cavity (11), glue is not filled in the first cavity, and the first installation opening (111) is not covered with the first protective cover (115); and / or After at least the second chip is installed in the second cavity (12), the second glue potting structure is filled in the remaining space in the second cavity (12); or after at least the second chip is installed in the second cavity (12), the second installation opening (121) is covered with a second protective cover (125); or after at least the second chip is installed in the second cavity (12), the second glue potting structure is filled in the remaining space in the second cavity (12), and the second installation opening (121) is covered with a second protective cover (125).

7. The packaging assembly of the pressure sensor according to claim 6, characterized in that: The first glue-filling structure is soft jelly silica gel; and / or The second glue pouring structure is hard epoxy glue or polyurethane glue.

8. The packaging assembly of the pressure sensor according to claim 1, characterized in that: An annular sealing structure is arranged between the first circuit adapter board (5) and the first cavity (11), and the annular sealing structure is arranged around the periphery of the air hole.

9. The packaging assembly of the pressure sensor according to claim 6, characterized in that: The pressure chip (3) is an absolute pressure chip with pressure on the back side, and the first installation opening (111) is covered with a first protective cover (115).

10. The packaging assembly of the pressure sensor according to claim 8, characterized in that: A sealing groove (116) is provided on the inner wall of the first cavity (11), and the annular sealing structure is accommodated in the sealing groove (116).

11. The packaging assembly of the pressure sensor according to claim 3, characterized in that: A through hole (122) for passing the measured medium is provided at the bottom of the second cavity (12), and the back side of the IC chip is configured to be in contact with the measured medium to sense the temperature of the measured medium.

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