JP7575333B2 - Sensor Device - Google Patents

Description

The present invention relates to various sensor devices such as diaphragm vacuum gauges.

Patent Document 1 discloses a sensor device that includes a sensor unit (sensor 2 and heater H) that includes a sensor that is heated by a heater, a circuit board (board 31) that is spaced above the sensor unit, wiring (connector 5 or a signal line therein) that connects the sensor unit and the circuit board, and a case (outer case 41) that houses the sensor unit, the circuit board, and the wiring.

JP 2007-155500 A

In the above sensor device, when the heater heats the sensor, the heat moves upward through the gap between the wiring and the insulation material and heats the circuit board.

The present invention was made in consideration of the above points, and aims to prevent the circuit board from being heated by the heat generated when the sensor is heated by the heater.

In order to solve the above problems, the sensor device according to the present invention comprises a sensor unit including a sensor heated by a heater, a circuit board arranged above the sensor unit with a gap therebetween, wiring connecting the sensor unit and the circuit board, and a case accommodating the sensor unit, the circuit board, and the wiring. The case comprises a ceiling plate that divides the space within the case into a first space accommodating the circuit board and a second space below the first space and above the sensor unit, and a cylindrical side wall that constitutes an inner wall surface that divides the second space. The wiring runs vertically from the sensor unit through the second space and reaches the circuit board through a hole formed in the ceiling plate. The side wall is provided with an inlet through which air outside the case flows into the second space, and an outlet located above the inlet through which the air that has flowed into the second space flows out to the outside of the case.

The sensor unit may include the heater and a temperature sensor that measures the temperature of the sensor, and the wiring may connect the sensor, the heater, or the temperature sensor to the circuit board.

The wiring may be arranged so that the air flowing in from the inlet passes through a position where the air crosses the wiring.

The wiring may be arranged so that it passes through a position where the air flowing in from the inlet directly hits the wiring.

The case may be provided with a backflow prevention plate extending downward from the end of the ceiling plate on the inlet side to prevent air that has flowed into the second space from the inlet from flowing back toward the inlet side.

A thermal insulator may be further provided between the second space and the sensor unit.

The present invention prevents the circuit board from being heated by the heat generated when the sensor is heated by the heater.

FIG. 1 is a cross-sectional view of a main part of a sensor device according to an embodiment of the present invention. FIG. 2 is a schematic diagram showing the positional relationship between an inlet and an outlet provided in a side wall. FIG. 3 is a cross-sectional view for explaining the air flow within the sensor device.

The sensor device according to the embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, the sensor device 10 according to this embodiment is connected to a pipe H connected to a vacuum chamber T of a semiconductor control device or the like via a joint (not shown), and is configured as a diaphragm vacuum gauge that measures the air pressure of the process gas introduced from the vacuum chamber T to the pipe H.

The sensor device 10 includes a sensor unit 20, a heat insulating unit 30, a circuit board 40, and a case 50. The sensor device 10 also includes wiring L1 to L3 that connects the sensor unit 20 and the circuit board 40. Note that in FIG. 1, wiring L1 to L3 are depicted as an elevation view rather than a cross-sectional view.

The sensor unit 20 includes a pressure sensor 21, a terminal board 22, a heater 25, a heater support member 26, and a temperature sensor 27.

The pressure sensor 21 includes a vacuum chamber R1 and an inflow chamber R2 into which the process gas in the pipe H flows in, inside the case 21A. The pressure sensor 21 is configured to detect the air pressure of the process gas. Specifically, the pressure sensor 21 includes a sensor element 21B (schematically drawn as a block in FIG. 1 and other figures) disposed at the boundary between the vacuum chamber R1 and the inflow chamber R2, and a conductive pin 21C connected to the sensor element 21B. The sensor element 21B has a diaphragm that deforms in response to the differential pressure between the vacuum chamber R1 and the inflow chamber R2. The sensor element 21B detects the air pressure of the process gas based on the air pressure of the vacuum chamber R1 by outputting an electrical signal indicating a resistance value or electrostatic capacitance value corresponding to the degree of deformation of the diaphragm. The conductive pin 21C penetrates the case 21A and transmits the electrical signal output by the sensor element 21B to the outside of the case 21A.

The conductive pin 21C is electrically connected to the wiring L1, which is a coaxial cable, via a conductive terminal plate 22. The connection between the terminal plate 22 and the conductive pin 21C, and between the terminal plate 22 and the wiring L1 are performed by welding or the like. A cylindrical shield may be provided to surround the conductive pin 21C and connected to the outer conductor of the coaxial cable, so that the signal potential of the conductive pin 21C and the like is not affected by the potential of the metal case 21A of the pressure sensor 21. Although the number of conductive pins 21C and wiring L1 is one in FIG. 1, it may be two or more.

The heater 25 heats the pressure sensor 21 to prevent the process gas from precipitating inside the pressure sensor 21. The heater 25 is a cylindrical band heater (the internal structure is omitted in FIG. 1) and is fastened to a cylindrical heater support member 26. This fastening allows the heater support member 26 to support the heater 25. Power is supplied to the heater 25 from the circuit board 40 via the wiring L2. This power supply causes the heater 25 to generate heat. The heater support member 26 has an annular protrusion 26A that protrudes inward. The protrusion 26A engages with a step on the outer periphery of the pressure sensor 21. This engagement allows the heater support member 26 to be supported by the pressure sensor 21 together with the heater 25.

The temperature sensor 27 is in contact with the pressure sensor 21 and detects the temperature of the pressure sensor 21 heated by the heater 25. The internal structure of the temperature sensor 27 is omitted in FIG. 1. The temperature sensor 27 outputs the detected temperature to the circuit board 40 via the wiring L3.

The heat insulating section 30 comprises a cylindrical heat insulating material 31 that surrounds the sensor section 20, and a disk-shaped heat insulating material 32 that is disposed above the sensor section 20. The heat insulating section 30 as a whole covers the sensor section 20 from above, and insulates against heat from the heater 25 or the pressure sensor 21 so that the heat does not adversely affect the circuit board 40, etc. The heat insulating materials 31 and 32 are made of any material (such as synthetic resin) that has a heat insulating effect. The heat insulating material 32 prevents heat from the pressure sensor 21, etc. from moving upward.

The circuit board 40 is constructed by assembling a plurality of boards. Circuits (including microcomputers, etc.) that perform various processes are mounted on the circuit board 40. Wires L1 to L3 are connected to the circuit board 40. For example, when the sensor element 21B is a capacitive type, the circuit board 40 applies an AC voltage to the sensor element 21B through one of the plurality of wires L1. Furthermore, the circuit board 40 acquires a voltage signal that changes according to the capacitance value of the capacitor constituted by the sensor element 21B through one of the plurality of wires L1. As a result, the electrical signal output by the sensor element 21B and taken out by the conductive pin 21C is transmitted by the wire L1 and supplied to the circuit board 40. The circuit board 40 performs processing based on the acquired electrical signal. For example, the circuit board 40 amplifies the electrical signal, converts it from analog to digital, etc., to obtain data in a predetermined format that represents the air pressure of the process gas indicated by the electrical signal. This predetermined format data is, for example, data in a format that can be handled by a higher-level device of the sensor device 10 (for example, a controller of a semiconductor manufacturing device, etc.), and is output to the higher-level device. The circuit board 40 receives the temperature output from the temperature sensor 27 via the wiring L3, and uses the temperature as a feedback value to control the power supplied to the heater 25 via the wiring L2 so that the pressure sensor 21 reaches the desired temperature (e.g., 200°C). As described above, the circuit board 40 controls the sensor unit 20 via the wirings L1 to L3.

The case 50 houses the sensor unit 20, the heat insulating unit 30, the circuit board 40, and the wiring L1 to L3. The case 50 includes a sensor case 51 that houses the sensor unit 20 and the heat insulating unit 30, and a board case 56 that houses the circuit board 40.

The sensor case 51 comprises a cylindrical inner case 52 having a thickness in the radial direction as a whole, and a cup-shaped outer case 53 that covers the inner case 52 from the outside. The inner case 52 is composed of an upper inner case 52A having an annular shape with an inverted U-shaped cross section, and a cup-shaped lower inner case 52B with a through hole in the center. The inner case 52 contains a cylindrical insulating material 31 inside. The disk-shaped insulating material 32 is fitted into the inner wall of the upper inner case 52A. The insulating material 32 is flexible, and presses the wiring L1 to L3 passing through the upper inner case 52A against the inner wall of the upper inner case 52A. The wiring L1 to L3 are sandwiched and held between the insulating material 32 and the inner wall of the upper inner case 52A in a manner that the outer periphery of the insulating material 32 wraps around the periphery. The inner case 52 is made of synthetic resin so as not to impede the insulating effect of the insulating material 31. On the other hand, the outer case 53 is made of metal. The sensor case 51 has an overall cup shape with a through hole in the center of the bottom, and the opening at the top is covered with a heat insulating material 32.

The board case 56 is made of metal or synthetic resin and covers the sensor case 51 from above. The board case 56 defines a first space R11 that houses the circuit board 40, and a second space R12 below the first space and above the insulating material 32. The second space R12 is partitioned by the upper part of the sensor case 51, the board case 56, and the insulating material 32. The insulating material 32 is disposed between the second space R12 and the sensor unit 20, and provides insulation to prevent heat from being transferred to the second space R12 when the heater 25 heats the pressure sensor 21.

The substrate case 56 divides the space within the case 50, more specifically the space surrounded by the substrate case 56, into a first space R11 and a second space R12, and includes a ceiling plate 56A that constitutes a ceiling that defines the second space R12. The substrate case 56 further includes a cylindrical side wall 56B that surrounds the second space R12 and constitutes an inner wall surface that defines the second space R12. Here, the side wall 56B has a rectangular tube shape, but it may also have a cylindrical shape, etc.

The ceiling plate 56A has a through hole H1 (including a notch) that penetrates vertically near the right side wall 56B. Wires L1 to L3 pass through the through hole H1. Wire L1 extends from the terminal plate 22 to the left, then passes upward and around the outer periphery of the heat insulating material 32, then extends to the right, then passes upward and through the through hole H1 to reach the circuit board 40. Wires L2 and L3 pass from the sensor unit 20 through the outer periphery of the heat insulating material 32, and run vertically through the second space R12 to reach the circuit board 40. Wire L1 may also run vertically through the second space R12 to reach the circuit board 40, just like wires L2 and L3. In this case, wire L1 extends to the right from the terminal plate 22.

As shown in Figures 1 and 2, the side wall 56B is provided with an inlet 56BA consisting of a through hole and multiple outlets 56BB. The inlet 56BA is provided closer to the wires L2 and L3 than the outlet 56BB. The multiple outlets 56BB face the inlet 56BA at a position on the side wall 56B above the inlet 56BA and in the left-right direction perpendicular to the up-down direction, sandwiching the wires L1 to L3 between them.

Here, the inlet 56BA and the outlet 56BB will be described in more detail with reference to Figure 3. When the pressure sensor 21 is heated by the heater 25, the air around the pressure sensor 21 is also heated. The heated air passes through the gap between the wiring L2 or L3 and the insulating material 32 or the upper inner case 52A and moves upward along the wiring L2 or L3, as indicated by the arrow X1 in Figure 3. If the inlet 56BA and the outlet 56BB are not provided in the side wall 56B, this air passes through the through hole H1 to reach the circuit board 40 and heats the circuit board 40. In this embodiment, the side wall 56B is provided with an inlet 56BA located closer to the wire L2 or L3 than the outlet 56BB, and an outlet 56BB located above the inlet 56BA and facing the inlet 56BA across the wires L2 and L3 in the left-right direction perpendicular to the up-down direction, so that the heating can be suppressed (more specifically, eliminated or reduced). Specifically, when the pressure sensor 21 is heated by the heater 25, the air below in the second space R12 is heated to a certain extent, although there is an insulating effect due to the insulating part 30. As a result, the air moves upward and flows out of the case 50 from the outlet 56BB located above. This causes the air pressure in the upper part of the second space R12 to decrease, and the air outside the case 50 flows into the second space R12 from the inlet 56BA (flowing from right to left). 3, the air that flows in crosses the wires L2 and L3, engulfs the heated air moving upward, and flows diagonally upward due to the heat of the heated air, and finally flows out of the case 50 from the outlet 56BB. This air flow, i.e., natural convection, causes the heated air that flows upward through the gap, i.e., the heat generated when the heater 25 heats the sensor 21, to be discharged from the outlet 56BB to the outside of the case 50, thereby preventing the circuit board 40 from being heated. Furthermore, in this embodiment, the air that flows in from the inlet 56BA crosses the wires L1 to L3 (crosses from right to left), and therefore the air can cool the wires L1 to L3. Therefore, the amount of heat (heat from heater 25, heat from temperature sensor 27, heat from sensor 21, or heat from the surrounding air heated by heater 25) that reaches circuit board 40 through wiring L1-L3 when sensor 21 is heated by heater 25 is also reduced, and heating of circuit board 40 by heat from pressure sensor 21 when it is heated is also suppressed.

The positions of the inlet 56BA and the outlet 56BB are not limited to the positions described above, and may be positions where the air flowing into the second space R12 from the inlet 56BA can flow out from the outlet 56BB across the wiring L2 and L3. This prevents the circuit board 40 from being heated by the heat generated when the pressure sensor 21 is heated by the heater 25. The number of inlets 56BA and the number of outlets 56BB are arbitrary, but if the total opening area of the inlets 56BA is less than the total opening area of the outlets 56BB, the above-mentioned natural convection is likely to occur. The relationship between the opening areas is arbitrary, and the opening area of the inlet 56BA may be larger. It is preferable that the side wall 56B on which the outlet 56BB is provided does not have a through hole at the same height as the inlet 56BA or lower. This makes it easier for the above-mentioned natural convection to occur, and prevents the heated air from being trapped near the ceiling of the second space R12. In addition, to prevent the air that passes through the air inlet 56BA from moving upward, the circuit board case 56 may be provided with a plate material 56C that extends in the left-right direction and serves as a member that constitutes the ceiling of the air inlet 56BA so that the air moves in the left-right direction.

As shown in Figs. 1 and 3, the inlet 56BA is preferably positioned at a position where the air that has passed through the inlet 56BA hits the wires L2 and L3 directly. "Directly hitting" means that the air hits the wires L2 and L3 before the air changes direction after passing through the inlet 56BA. This allows the heated air moving upward through the gap to be more effectively moved toward the outlet 56BB. Furthermore, as shown in Figs. 1 and 3, by being positioned at a position where the air that has passed through the inlet 56BA hits the wires L1 to L3 directly, the wires L1 to L3 can be effectively cooled, the heat transmitted through the wires L1 to L3 can be effectively reduced, and heating of the circuit board 40 can be effectively suppressed.

As shown in FIG. 2, the circuit board case 56 may be provided with a backflow prevention plate 56D extending downward from the end of the ceiling plate 56A on the inlet 56BA side to prevent air that has flowed into the flow path from the inlet 56BA from flowing back toward the inlet 56BA side. This prevents heated air from flowing toward the circuit board 40 side.

Various modifications are possible to the above embodiment. For example, the shape of each component described above is arbitrary. The cylinder, disk, etc. described above can be changed to a polygonal tube, polygonal plate, etc., respectively. The present invention is also applicable to sensor devices other than diaphragm vacuum gauges. The sensor device to which the present invention is applied may be a device that measures a physical quantity other than pressure. The heater 25 may be provided separately from the sensor device 10 and attached from the outside of the sensor device 10 to heat the pressure sensor 21. The wiring L1 to L3 may pass through the outer periphery (peripheral part) of the insulating material 32 as described above, or may pass through any part of the insulating material 32. The connection destination of the wiring connecting the sensor unit 20 and the circuit board 40 on the sensor unit 20 side can be changed depending on what parts the sensor unit 20 has, and is not limited to the above embodiment. The insulating material 32, etc. may be omitted. Even in such a case, the heat (e.g., air heated by heat) that moves upward from the sensor unit 20 when the heater 25 heats the sensor 21 can be discharged to the outside of the case 50 by the air flowing from the inlet 56BA to the outlet 56BB, suppressing heating of the circuit board 40.

Although the present invention has been described above with reference to the embodiments and modifications, the present invention is not limited to the above-mentioned embodiments and modifications. For example, the present invention includes various modifications to the above-mentioned embodiments and modifications that can be understood by a person skilled in the art within the scope of the technical concept of the present invention. The configurations listed in the above-mentioned embodiments and modifications can be combined as appropriate within a range that does not cause inconsistencies.

10...sensor device, 20...sensor section, 21...pressure sensor, 21A...case, 21B...sensor element, 21C...conductive pin, 22...terminal board, 25...heater, 27...temperature sensor, 30...insulating section, 31...insulating material, 32...insulating material, 40...circuit board, 50...case, 51...sensor case, 52...inner case, 52A...upper inner case, 52B...lower inner case, 53...outer case, 56...board case, 56A...ceiling plate, 56B...side wall, 56BA...inlet, 56BB...outlet, 56C...plate, 56D...backflow prevention plate, H1...through hole, L1-L3...wiring, R1...vacuum chamber, R2...inlet chamber, R11...first space, R12...second space.

Claims (6)

a sensor unit including a sensor heated by a heater;
a circuit board disposed above the sensor unit with a gap therebetween;
A wiring that connects the sensor unit and the circuit board;
a case that houses the sensor unit, the circuit board, and the wiring;
the case includes a ceiling plate that divides a space within the case into a first space that accommodates the circuit board and a second space below the first space and above the sensor unit, and a cylindrical side wall that constitutes an inner wall surface that divides the second space,
the wiring extends vertically from the sensor unit through the second space and through a hole formed in the ceiling plate to the circuit board,
The side wall is provided with an inlet through which air outside the case flows into the second space, and an outlet arranged at a position above the inlet through which the air that has flowed into the second space flows out to the outside of the case.
Sensor device. the sensor unit includes the heater and a temperature sensor that measures a temperature of the sensor,
The wiring connects the sensor, the heater, or the temperature sensor to the circuit board.
The sensor device according to claim 1 . The wiring passes through a position where the air flowing in from the inlet crosses the wiring.
The sensor device according to claim 1 or 2. The wiring passes through a position where the air flowing in from the inlet directly hits the wiring.
The sensor device according to claim 3 . The case includes a backflow prevention plate extending downward from an end of the ceiling plate on the inlet side to prevent the air that has flowed into the second space from the inlet from flowing back toward the inlet side.
The sensor device according to any one of claims 1 to 4. A heat insulating material is further provided between the second space and the sensor unit.
The sensor device according to any one of claims 1 to 5.

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