JP2008128890A - Gas flowmeter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the manufacture yield and the reliability of a gas flowmeter which keeps a circuit board loaded with a flow sensor mounted in such a way as to cover an opening recession part which forms a part of a channel incorporated in such a way as to be exposed in one surface of the flowmeter main body. <P>SOLUTION: The gas flowmeter has a structure provided with the circuit board to which a flow sensor is mounted in such a way as to cover the opening recession part provided for the one surface of the flowmeter main body. The gas flowmeter is provided with a rib having a prescribed height from the one surface of the flowmeter main body in such a way as to surround a peripheral part of the opening recession part, and a protrusion supporting the circuit board at the same height as the rib is provided for a section of the one surface of the flowmeter separated from the rib. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a small-sized flow meter that is used by being mounted on a manifold body in which, for example, a gas introduction path and a discharge path are formed, and more particularly, a gas flow meter having a simple structure that improves manufacturing yield and reliability. About.

As a technique for confirming the adsorption of a minute part by an adsorption nozzle in a chip mounter, an attempt has been made to detect a change in the minute flow rate in the adsorption nozzle by using a flow rate sensor instead of a conventional pressure sensor. As a small-sized flow meter used for this type of application, a circuit board with a flow sensor mounted thereon is mounted so as to cover an opening recess that forms a part of the flow path provided on one surface of the flow meter body. There has been proposed a substrate whose structure is simplified by using a substrate as one wall surface of the flow path and causing the flow rate sensor to face an opening recess (see, for example, Patent Document 1). It has also been proposed that when the circuit board is bonded and fixed to one surface of the flowmeter main body, ribs are provided on the peripheral edge of the opening recess in order to prevent the adhesive from flowing into the opening recess.
JP 2004-3883 A

  By the way, on the circuit board on which the flow sensor is mounted, a drive circuit composed of a large number of resistor chips, IC chips for measurement and calculation, and connectors for external connection are mounted. For this reason, it cannot be denied that the circuit board is increased in size as compared with the opening recess forming part of the flow path. Therefore, when the circuit board is placed on one surface of the flow meter body where the opening recess is provided, the central portion of the flow meter body is lifted by the rib described above, so the circuit board is inclined with respect to the one surface of the flow meter body. easy. If the circuit board is adhered and fixed to the flowmeter body with the circuit board tilted, the sealing performance against the opening recess (flow path) may be impaired. Moreover, depending on the shape of the rib, it may be difficult to evenly fill the adhesive along the periphery of the rib, and the adhesive may be peeled off over time.

  The present invention has been made in consideration of such circumstances, and an object of the present invention is to provide a gas flow meter having a simple structure that improves the manufacturing yield and reliability.

  In order to achieve the above-described object, a gas flowmeter according to the present invention is provided with an opening recess that forms a measurement channel on one surface and a pair of communication passages that are respectively connected to both ends of the opening recess. The main body and a flow sensor are mounted, and the flow sensor is mounted on one surface of the flow meter main body so as to face the opening concave portion and includes a circuit board that closes the peripheral edge of the opening concave portion. In particular, a rib having a certain height is provided from one surface of the flow meter body so as to surround the peripheral edge of the opening recess, and the circuit board is disposed at a position away from the rib on one surface of the flow meter body. It is characterized in that a protrusion for supporting the height is provided.

  Incidentally, the circuit board is bonded and fixed onto the rib by an adhesive filled along the periphery of the rib. In addition, the flow meter main body includes a fluid introduction port and a fluid discharge port respectively connected to a fluid introduction path and a discharge path provided in a manifold body, for example, on a lower surface, and a concave substrate on which the circuit board is mounted on the upper surface side A mounting portion is provided, and the opening concave portion is provided at a substantially central portion of the substrate mounting portion.

  According to the gas flow meter having the above-described configuration, the circuit board is disposed at a portion away from the rib, with a rib having a certain height from one surface of the flow meter body surrounding the peripheral edge of the opening recess provided on the one surface of the flow meter body. Since the protrusion supporting the same height as the rib is provided, the circuit board can be placed without causing an inclination with respect to one surface of the flowmeter body. Therefore, the circuit board can be brought into close contact with the upper end of the rib surrounding the peripheral edge of the opening recess, and the circuit board can be adhered and fixed to the flowmeter main body in this state, so that the sealing performance can be sufficiently secured. .

  In addition, since the circuit board can be positioned parallel to one surface of the flow meter body, the thickness of the adhesive to be filled along the periphery of the rib can be made uniform, so that the adhesive can be partially removed over time. This does not cause a problem of peeling off. Therefore, the reliability can be sufficiently increased.

Hereinafter, a gas flow meter according to an embodiment of the present invention will be described with reference to the drawings.
This gas flow meter is a small one that is used by being attached to a manifold body made of a thick plate made of aluminum, for example, having a through hole that forms a gas introduction path and a discharge path. It has a substantially rectangular parallelepiped external shape with a size of about 10 mm and a height of about 10 mm. This gas flow meter basically includes a flow meter body in which a flow path connecting an introduction path and a discharge path is formed, and a gas that is incorporated into the flow path of the flow meter body and flows through the manifold body. And a mass flow rate sensor for measuring the flow rate.

  FIG. 1 is an external perspective view showing a schematic configuration of a gas flow meter according to this embodiment, and FIG. 2 is a cross-sectional view showing an internal structure of the gas flow meter and an assembly structure to a manifold body. The flow meter main body 10 is made of a resin mold having a substantially rectangular parallelepiped shape, and includes a fluid inlet 11 and a fluid outlet 12 connected to the inlet path 31 and the outlet path 32 of the manifold body 30 on the lower surface thereof. As will be described later, a flow path connecting the fluid introduction port 11 and the fluid discharge port 12 is formed therein. Further, on the upper surface of the flowmeter main body 10, a concave board mounting portion 13 having a predetermined depth for mounting a rectangular circuit board 20 described later is provided.

  The fluid introduction port 11 and the fluid discharge port 12 described above are provided side by side with a predetermined distance in the longitudinal direction of the flow meter main body 10, and an O-ring is attached to an opening edge portion thereof. Further, in the flow meter main body 10, the fluid introduction port 11 and the fluid discharge port 12 are measured in the direction in which the fluid introduction port 11 and the fluid discharge port 12 are arranged along the circuit board 20 attached to the substrate attachment unit 13. An opening recess 14 that forms the flow path is formed. The opening recess 14 forms a part of the flow path connecting the fluid introduction port 11 and the fluid discharge port 12 by closing the peripheral edge portion of the circuit board 20 mounted on the substrate mounting portion 13. .

  Further, the flow meter body 10 is formed with communication passages 15 and 16 that connect both ends of the opening recess 14 to the fluid inlet port 11 and the fluid outlet port 12, respectively. These communication passages 15 and 16 are connected to each other via the opening recess 14 whose peripheral portion is closed by the circuit board 20 described above, and a gas passage connecting the fluid introduction port 11 and the fluid discharge port 12. A flow path is formed.

  As shown in FIG. 2, these communication passages 15, 16 are displaced from the upper surface side (both ends of the opening recess 14) and the lower surface side of the flow meter body 10 by shifting their axial centers. The channel is composed of two vertical hole portions that are bored in the vertical direction to the midway position and a connecting portion that communicates between the bottoms of these vertical hole portions in the horizontal direction, and forms a channel that is bent in a bowl shape. The communication passages 15 and 16 having such a bent structure exhibit an effect of stabilizing the flow velocity distribution by guiding the gas flowing in from the fluid introduction port 11 while colliding with the wall surface.

  On the other hand, the circuit board 20 to be mounted on the board mounting portion 13 has a mass flow sensor 21 mounted at a substantially central portion on the lower surface side, and a drive circuit 22 for the mass flow sensor 21 and the drive circuit on the upper surface side. 22 external connection parts (connectors) 23 are mounted. Incidentally, the mass flow sensor 21 is not particularly shown, but for example, a heating resistance element is provided on a thin diaphragm formed on a semiconductor chip, and a pair of temperature sensors are provided with the heating resistance element sandwiched in the gas flow direction. Consists of things. The mass flow rate sensor 21 changes the temperature distribution of the ambient gas in the vicinity of the thin diaphragm heated by the heating resistor element according to the flow rate of the gas flowing along the thin diaphragm. By detecting by the sensor, it plays a role of detecting the flow velocity of the gas, and hence its mass flow rate. The drive circuit 22 includes a plurality of resistors and transistors for constructing a resistance bridge circuit and the like for driving the heating resistance element and the temperature sensor described above in the mass flow sensor 21, and a micro that calculates the flow rate from the output of the temperature sensor. It consists of a processor.

  The circuit board 20 on which such a mass flow sensor 21 and its drive circuit 22 are mounted is mounted on the board mounting portion 13 with its lower surface facing the opening recess 14. As a result, the mass flow sensor 21 mounted on the circuit board 20 is positioned facing the measurement flow path formed by the opening recess 14. At this time, the peripheral edge of the opening recess 14 is closed by the circuit board 20 by bonding the peripheral edge of the opening recess 14 and the lower surface of the circuit board 20 with an adhesive.

  In addition, a pair of flanges 18 are provided below the opposite ends of the flowmeter main body 10 in the longitudinal direction so as to project from the respective ends connected to the lower surface thereof. Specifically, these flanges 18 are located at both ends of the flow meter body 10 in the direction in which the fluid introduction port 11 and the fluid discharge port 12 are arranged, that is, at the middle part of the short side of the flow meter body 10. , And is formed as a protruding edge portion on the lower surface side of the lateral groove 19 provided in the width direction.

  The upper surfaces of the flange portions 18 are pressed by a rod-shaped fixing member 40 that is assembled in parallel to the manifold body 30 so as to be sandwiched between the manifold body 30. It plays the role of mounting firmly. The rod-shaped fixing member 40 is longer than the width of the end portion of the flowmeter body 10 where the flange portion 18 is provided, and is inserted into the manifold through a screw hole 41 provided at the end portion. It is fixed to the manifold body 30 by screws 42 screwed onto the body 30.

  In the case where the fixing member 40 is provided with a step portion 43 that engages with the flange portion 18, the height of the step is set slightly lower than the thickness of the flange portion 18. At this time, if the opening width of the stepped portion 43 in the longitudinal direction of the fixing member 40 is set to be approximately the same as the width of the end surface on the short side of the flowmeter main body 10, the flange portion 18 is fitted into the stepped portion 43. By combining, the lateral displacement of the flow meter main body 10 can be prevented. When the fixing member 40 having such a structure is fixed to the manifold body 30, the flow meter main body 10 is tightly fixed to the upper surface of the manifold body 30 by the fixing member 40.

  Further, the flow meter (flow meter main body 10) is attached to the manifold body 30 by connecting the fluid introduction port 11 and the fluid discharge port 12 provided on the lower surface of the flow meter main body 10 to the introduction path 31 and the discharge path 32 in the manifold body 30. Of course, it is performed in alignment with each opening. When the flow meter (flow meter main body 10) is fixed to the upper surface of the manifold body 30 in this way, the O-rings attached to the respective opening edges of the fluid introduction port 11 and the fluid discharge port 12 as described above are used. The joint between the lower surface of the flow meter main body 10 and the upper surface of the manifold body 30 is hermetically sealed, the fluid inlet 11 and the inlet path 31 are connected without a gap, and the fluid outlet 12 and the outlet path 32 are connected. Connected without gaps.

  Now, the gas flow meter according to the present invention basically comprising the flow meter body 10 and the circuit board 20 having the above-described structure is characterized in that the substrate mounting in the flow meter body 10 described above with reference to FIG. As shown in an enlarged view of the portion 13, along the peripheral edge of the opening recess 14, there is provided a rib 51 having a constant height that surrounds the opening recess 14, and is separated from the rib 51 in the longitudinal direction of the flow meter body 10. This is because a protrusion 52 for supporting the circuit board 20 at the same height as the rib 51 is provided at the site. The ribs 51 and the protrusions 52 have a height from the bottom surface of the substrate mounting portion 13 formed in a concave shape of about 0.1 to 0.2 mm. It plays the role of lifting the substrate 20 and supporting it in parallel without bending. Further, the rib 51 prevents the adhesive filled between the bottom surface of the board mounting portion 13 and the circuit board 20 from flowing into the opening recess 14, and cooperates with the protrusion 52 to prevent the adhesive from flowing. Plays the role of uniform thickness. Particularly in this embodiment, the rib 51 is formed as a quadrangular protrusion that surrounds the opening recess 14 by four sides parallel to the outer peripheral wall of the substrate mounting portion 13.

  If the flow meter body 10 has such ribs 51 and protrusions 51 on the bottom surface of the board mounting portion 13, the bottom surface of the board mounting portion 13 is shown in FIG. In contrast, the circuit board 20 can be lifted by a certain height and supported in parallel and stably. In addition, even if the circuit board 20 is pressed toward the bottom surface of the board mounting portion 13, the support posture of the circuit board 20 does not change. Therefore, if a predetermined amount of adhesive 53 is filled along the periphery of the rib 51 on the bottom surface of the substrate mounting portion 13, the adhesive 53 is interposed between the bottom surface of the substrate mounting portion 13 and the circuit board 20. The bottom surface of the board mounting portion 13 and the circuit board 20 are bonded and fixed while expanding along the gap in a state where the thickness is regulated. At this time, needless to say, the rib 51 prevents the adhesive 53 from flowing into the opening recess 14. As a result, the circuit board 20 is stably bonded and fixed to the flowmeter main body 10 by the adhesive 53 having a constant thickness.

  As described above, according to the present invention, the substrate mounting portion 13 of the flowmeter main body 10 is provided with the rib 51 having a constant height so as to surround the opening recess 14, and the circuit board together with the rib 51 at a position away from the rib 51. Since the protrusions 52 that support the substrate 20 at a constant height are provided, the circuit board 20 can be stably mounted with a simple configuration. As a result, the peripheral edge of the opening recess 14 can be reliably sealed by the adhesive 53 filled along the ribs 51, and the sealing performance of the flow path portion constituted by the opening recess 14 and the circuit board 20 can be ensured. Can be. Therefore, the production yield can be increased by suppressing the occurrence of defective seals, and the mounting posture can be stabilized constantly only by pressing down the circuit board 20, so that the production efficiency can be improved. Furthermore, since the thickness of the adhesive 53 can be made constant, it is possible to suppress the occurrence of distortion with the passage of time of the solidified adhesive 53 as much as possible, and to effectively prevent the partial peeling thereof. it can. Therefore, such an effect that the operation reliability can be sufficiently secured can be achieved.

  The present invention is not limited to the embodiment described above. For example, the heights of the ribs 51 and the protrusions 52 may be set according to the thickness that can ensure the necessary adhesive strength by the adhesive 53. Further, the protrusions 52 may be provided at the corners of the board mounting part 13 to support the corners of the circuit board 20. In addition, the present invention can be variously modified and implemented without departing from the scope of the invention.

1 is an external perspective view showing a schematic configuration of a gas flow meter according to an embodiment of the present invention. Sectional drawing which shows the assembly structure to the internal structure and manifold body of the gas flowmeter shown in FIG. The perspective view which expands and shows the structure of the board | substrate mounting part in a flowmeter main body. Sectional drawing which shows the support structure of the circuit board by a rib and protrusion.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Flowmeter main body 11 Fluid introduction port 12 Fluid discharge port 13 Board | substrate mounting part 14 Opening recessed part (measurement flow path)
15 and 16 Communication path 20 Circuit board 30 Manifold body 40 and 45 Fixing member 51 Rib 52 Projection

Claims (3)

A flow meter main body provided with an opening recess that forms a measurement flow path on one surface, and a pair of communication passages that are respectively connected to both ends of the opening recess.
A flow rate sensor, and a circuit board that is mounted on one surface of the flow meter body so that the flow rate sensor faces the opening recess and closes the peripheral edge of the opening recess,
A rib having a constant height is provided from one surface of the flow meter body so as to surround the peripheral edge of the opening recess, and the circuit board is placed at the same height as the rib at a position away from the rib on one surface of the flow meter body. A gas flowmeter characterized by providing a supporting protrusion.   The gas flowmeter according to claim 1, wherein the circuit board is bonded and fixed onto the rib with an adhesive filled along the periphery of the rib. The flow meter body has a fluid introduction port and a fluid discharge port connected to a fluid introduction path and a discharge path, respectively, provided in the manifold body on the lower surface, and a concave substrate mounting portion for mounting the circuit board on the upper surface side. Provided,
The gas flow meter according to claim 1, wherein the opening recess is provided at a substantially central portion of the substrate mounting portion.

Images