JPH0979880A - Flow sensor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To resolve a problem caused by the sealing of a resin by applying a hermetic seal structure to a flow sensor device. SOLUTION: This flow sensor device is provided with a container 3 having a bottom face 2 kept in contact with a measured fluid, a thermal thermistor flow sensor 4 arranged at the bottom section of the container 3, a cover 1 hermetically closing the container 3, a terminal 5 provided on the cover 1 and connecting the inside and outside of the cover 1 for the electrical connection between the flow sensor 4 and the outside, and a connecting means connecting the flow sensor 4 and the terminal 5. No resin is filled in the container 3 on the flow sensor 4. The connecting means is arranged in the container 3, for example, and it is provided with a connector 6 connecting the flow sensor 4 and the terminal 5. When the cover 1 is closed, the terminal 5 is brought into contact with the connector 6, and the electrical connection between the flow sensor 4 and the terminal 5 is established.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow rate sensor device having a thermal type thermistor flow rate sensor arranged at the bottom of a container in contact with a fluid to be measured and for measuring the flow rate of the fluid to be measured flowing through piping or the like.

[0002]

2. Description of the Related Art In a flow sensor device having a thermal type thermistor flow sensor arranged at the bottom of a container in contact with a fluid to be measured, conventionally, the inside of the container above the flow sensor is connected to the flow sensor and the outside. For the purpose of thermal insulation of the flow sensor and protection of the flow sensor, etc., by enclosing a resin layer having a heat insulating property and a resin layer having water resistance, and pulling out the lead wire from the flow sensor through this resin, Has been electrically connected to.

However, according to the above-mentioned technique of encapsulating the resin, it takes time to dry the resin, so that the manufacturing time is long and there are many steps. Further, when the resin is dried, the solvent in the resin is vaporized and becomes a gas, which damages the electrodes and the like of the flow rate sensor. Furthermore, when the resin is filled into the container, air bubbles are mixed into the resin, which affects the heat insulation of the resin and causes variations in the product characteristics, and the product characteristics are controlled uniformly. There is also the problem that it is impossible to do.

On the other hand, conventionally, in order to accommodate an element such as a semiconductor device or an optical sensor, a package in which an extraction electrode is provided on a specific metal or ceramics (hereinafter referred to as a stem)
A technique is known in which an element is fixed / wired to, a cap is placed on the element, and a hermetic seal is provided between the cap and the stem. It is also possible to apply this hermetic seal technology to a thermal type thermistor flow sensor.

However, when the technique of the hermetically sealed structure using the cap and the stem is applied to the thermal type thermistor flow sensor, the flow sensor element is provided on the cap side so that the cap side is brought into contact with the fluid to be measured. There is no choice but to take the structure of thermal contact.
In addition, the thermal contact must use a reproducible method such as soldering. Therefore, as the manufacturing procedure, since the flow sensor is fixed to the cap side and then the stem is fixed by the hermetic seal, unlike the semiconductor device in which the element is attached to the stem side,
Since the element is attached to the cap side, it is necessary to devise a way to draw the wiring from the flow sensor to the outside.

In view of the above problems of the prior art, an object of the present invention is to solve the problem of wiring from the flow rate sensor to the outside when the above hermetic seal structure is applied to the flow rate sensor device. The purpose of the present invention is to make it possible to apply the hermetic seal structure as described above to a flow rate sensor device, thereby solving the problems of the conventional technology due to the encapsulation of resin.

[0007]

In order to achieve this object, according to the present invention, a flow sensor comprising a container having a bottom surface in contact with a fluid to be measured, and a thermal type thermistor flow sensor arranged at the bottom of the container. In the device, a lid for hermetically closing the container, a terminal provided on the lid for connecting the inside and the outside of the lid, and for making an electrical connection between the flow sensor and the outside of the device, and the flow sensor. And a connecting means for connecting the terminal and the terminal. The inside of the container on the flow sensor is not sealed with resin. Both the container and the lid are usually made of metal, and between them,
It is welded by resistance welding or laser welding.

According to this, since the labor for drying the resin is eliminated, the manufacturing process is simplified. Further, since the resin is not encapsulated, the problems caused by the solvent in the resin and the mixed air bubbles are solved. Further, since the container is sealed by the lid, the gas sealed in the container ensures sufficient heat insulation and reliability between the fluid sensor and the outside of the device.

More specifically, the connecting means includes a connector arranged in the container for connecting the flow rate sensor and the terminal, and the lid and the connector are formed by closing the lid. A terminal of the lid contacts the connector to establish an electrical connection between the flow sensor and the terminal. Further, in this case, more specifically, the connecting means includes a printed circuit board that connects between the flow rate sensor and the connector, the connector is directly connected and fixed on the printed circuit board, and the flow rate is The sensor and the printed circuit board are connected by wire bonding.

Alternatively, the connecting means is an FPC that directly connects the flow sensor and the terminal of the lid, and each connection end of the FPC on the flow sensor side has the same pitch as each terminal of the flow sensor. However, each connection end on the lid side has the same pitch as the terminals of the lid.

Alternatively, the connecting means includes a printed circuit board which is connected to the flow rate sensor by wire bonding at one end, and an FPC which connects the other end of the printed circuit board and a terminal of the lid.

By using the connector, the FPC and the terminal of the lid as described above, the connection between the flow sensor and the outside of the apparatus can be easily ensured.

It is preferable that the side surface of the container has a shape of a curved surface protruding to the outside, whereby the pressure resistance to the pressure (hydraulic pressure, hydraulic pressure, pneumatic pressure, etc.) of the fluid to be measured is improved.

Further, according to one aspect of the present invention, the temperature measuring thermistor is provided at the bottom of the container for measuring the temperature of the fluid to be measured, and the temperature measuring thermistor is connected to the outside of the apparatus. This is done through the same connection means as the flow sensor. According to this, it is not necessary to attach a temperature measuring thermistor for measuring the temperature of the fluid to be measured separately from the flow rate sensor, so that the device can be easily installed in the pipe or the like.

As the flow rate sensor, a thin film type flow rate sensor having a base material, a heating element thin film provided on the base material, and a thin film thermistor for measuring the temperature is usually used in view of sensitivity and compactness. It is preferably used.

As a preferred form of the container bottom, there is a convex portion or a concave portion conforming to the shape of the flow sensor and the thermistor, and the flow sensor and the thermistor are fixed on the convex portion or the concave portion, The printed circuit board is fixed to a bottom portion of the container other than the convex portion or the concave portion. According to this, the flow sensor or the like is accurately attached to the bottom of the container according to the shape of the convex portion or the concave portion, and the heat insulating state between the flow sensor or thermistor and the printed circuit board is preferably ensured. At the same time, the product-to-product variation in the heat insulation state is prevented.

[0017]

1 is a plan view showing a flow rate sensor device according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along line AA in FIG. However, FIG. 1 shows a state in which the lid 1 is removed. As shown in these figures, this device includes a container 3 having a bottom surface 2 in contact with a fluid to be measured, a thermal type thermistor flow sensor 4 arranged at the bottom of the container, and a lid 1 for hermetically closing the container 3. And a connector provided on the lid 1 for connecting the inside and the outside of the lid 1 for electrically connecting the flow sensor 4 to the outside of the apparatus, and a connector for connecting the flow sensor 4 and the terminal 5. 6 and a container 3 on the flow sensor 4
The inside is not filled with resin.

The connector 6 is arranged in the container 3 and the lid 1
And the connector 6 is provided with the terminal 5 by closing the lid 1.
Contacts the connector 6 to establish an electrical connection between the flow sensor 4 and the terminal 5. A glass 24 seals between the terminal 5 and the lid 1. In the present invention, the lid 1 is made of stainless steel in consideration of reliability. The device also includes a printed circuit board 7 that connects between the flow sensor 4 and the connector 6. The connector 6 is directly connected and fixed on the printed circuit board 7, and each terminal 8 of the connector 6 and the wiring pattern 9 on the printed circuit board 7 are connected by the solder 10. The flow sensor 4 and the printed circuit board 7 are connected by wire bonding 10. The connector 6 also has a function of supporting the space between the lid 1 and the printed circuit board 7 and improving the pressure resistance of the container 3.

This device further has a temperature measuring thermistor 11 arranged at the bottom of the container 3 for measuring the temperature of the fluid to be measured, and the temperature measuring thermistor 11 and the outside of the device are connected to the flow rate sensor 4. Similarly, it is performed through the printed circuit board 7 and the connector 6 and the terminal 5.

The flow sensor 4 is a thin film type flow sensor having a base material, a heating element thin film provided on the base material, and a thin film thermistor for measuring the temperature thereof.

The bottom of the container 3 has recesses 12 and 13 conforming to the shapes of the flow sensor 4 and the temperature measuring thermistor 11, and the flow sensor 4 and the temperature measuring thermistor 11 are fixed on the recesses 12 and 13, respectively. . The printed circuit board 7 is fixed to the bottom of the container 3 other than the recesses 12 and 13. Further, the side surface of the container 3 has a shape of a curved surface projecting outward, and the pressure resistance against the fluid to be measured is improved.

The container 3 is made of SUS316L, and is made thin within a range that does not hinder the strength. Therefore, the bottom portion of the container 3 does not transfer much heat in its surface direction, but allows good heat transfer in the vertical direction. Further, by making the thickness of the concave portion 12 portion, that is, the portion where the flow rate sensor 4 and the temperature measuring thermistor 11 are in contact with each other thinner than other portions, it is possible to improve the thermal efficiency and the sensitivity, and to improve the pressure resistance of the container 3. Can be made.

To manufacture this device, first, the flow sensor 4 and the temperature measuring thermistor 11 are fixed to the bottom of the container 3. The flow rate sensor 4 is fixed to the recess 12 using a solder material such as SnPb, AgSn, AuSn. This allows
Good thermal conductivity is ensured between the flow rate sensor 4 and the bottom of the container 3, and the solder material 13 is prevented from spreading laterally as shown in FIG. Therefore, the heat of the flow rate sensor 4 is prevented from escaping through the solder portion spread in the lateral direction, and the characteristics are stabilized between products. The temperature measuring thermistor 11 is fixed on the concave portion 13 with an adhesive.

On the other hand, in parallel with this, the connector 6 is fixed on the printed circuit board 7 on which a wiring pattern or the like is previously formed. This fixing is performed by soldering each terminal of the connector 6 to the corresponding terminal on the wiring pattern on the printed board 7.

Next, the printed circuit board 7 is fixed to a portion other than the recessed portions 12 and 13 at the bottom of the container 3. This fixation is
The same solder material as in the case of the flow rate sensor 4 is used. As a result, the printed board 7 having the copper plate on the back surface is
It is fixed to the bottom of the container 3 with high strength. Further, as described above, by disposing the flow rate sensor 4 and the temperature measuring thermistor 11 in the recesses 12 and 13 and disposing the printed circuit board 7 in the parts other than the recesses 12 and 13, they are respectively arranged with high accuracy, Therefore, the gap between the flow rate sensor 4 and the temperature measuring thermistor 11 and the printed circuit board 7 becomes constant.
Therefore, the heat of the flow rate sensor 4 and the temperature measuring thermistor 11 is uniformly prevented from escaping via the printed circuit board 7, the measurement accuracy is improved, and the characteristics of the device are stabilized between products.

Next, the connection terminals of the flow sensor 4 and the temperature measuring thermistor 11 and the corresponding terminals of the wiring pattern of the printed circuit board 7 are connected by wire bonding.

After the completion of the soldering process, elements such as the flow rate sensor 4 are immersed in a flux cleaning tank and ultrasonically cleaned to sufficiently remove the residual flux. At this time, since there is no resin sealing portion on the element, there is no steric hindrance by the resin and absorption of the flux liquid, and the residual flux in the electrode portion can be sufficiently removed.

Then, the lid 1 is attached to the container 3 in an inert gas atmosphere and sealed by a resistance welding machine or a laser welding machine. At this time, each terminal 5 of the container 1 is fitted into the corresponding terminal of the connector 6, and thereby the electrical connection between the terminal 5 and the flow rate sensor 4 and the temperature measuring thermistor 11 is established. Further, the dry inert gas sealed in the container 1 prevents deterioration of each element in the container 1, and
The thermal cutoff between the flow sensor 4 and the temperature measuring thermistor 11 is maintained. Also, when sealing with solder, reliability is low due to adverse effects such as the formation of conductive circuits due to chlorine in the flux, whereas hermetic sealing by this method has a proven track record in high-performance semiconductors and optical functional devices. As described above, with respect to moisture resistance, heat resistance, heat cycle, etc., the element is prevented from aging with high reliability.

As shown in FIG. 4, the flow rate sensor device manufactured in this manner is attached to the pipe 15 through which the fluid 14 to be measured flows through the O (O) ring 16 with the screw 17.

FIG. 8 is a partial pressure measuring circuit diagram at the time of measuring the flow rate by the present flow rate sensor device. As shown in the figure, 5 [V] is applied to the flow rate sensor 4 via the voltage dividing resistor R,
The flow rate is measured by measuring the voltage across the flow rate sensor 4. FIG. 5 is a graph illustrating the relationship between the voltage across the flow sensor 4 and the flow rate at various temperatures of the fluid to be measured in this circuit. Such a relationship is obtained in advance for the present flow rate sensor device, and when measuring the flow rate, the temperature of the fluid to be measured is detected by the temperature measuring thermistor 11, and the voltage across the flow rate sensor 4 is obtained to determine the flow rate. Can be measured.

FIG. 6 is a sectional view of a flow sensor device according to another embodiment of the present invention. This device, as shown in the figure,
Instead of the connector 6 in the apparatus of FIGS. 1 and 2, an FPC 18 for connecting the printed board 7 and the terminal 5 of the lid 1 is provided. As shown in FIG. 7, the FPC 18 is connected after fixing the printed circuit board 7 to the container 3 and before closing the container 3 with the lid 1. This connection can be made by soldering to both the printed circuit board 7 and the terminals 5.

In the case of FIG. 6, the FPC 18
Although the printed circuit board 7 is interposed between the flow sensor 4 and the temperature measuring thermistor 11, the FPC is directly connected to the flow sensor 4 and the temperature measuring thermistor 11 without using the printed circuit board 7. May be. However, in this case, each connection end on the flow sensor side of the FPC has the same pitch as each terminal of the flow sensor, and each connection end on the lid 1 side is the lid 1
It is preferable to have the same pitch as the terminals 5 of.

[0033]

As described above, according to the present invention, the hermetic seal structure can be applied to the flow rate sensor device without the problem of wiring from the flow rate sensor to the outside, and the encapsulation of resin can be eliminated. Therefore, the labor for drying the resin is eliminated, and the manufacturing process can be simplified. Further, since the resin is not enclosed, the problems caused by the solvent in the resin and the mixed air bubbles can be solved. Further, since the container is sealed by the lid, the heat insulation and reliability between the fluid sensor and the outside of the device can be sufficiently ensured by the inert gas sealed in the container. Further, by using the connector, the FPC and the terminal of the lid, it is possible to easily secure the connection between the flow sensor and the outside of the device.

Further, by forming the side surface of the container to have a curved surface protruding outward, the pressure resistance against the pressure (hydraulic pressure, hydraulic pressure, pneumatic pressure, etc.) of the fluid to be measured can be improved.

Further, a temperature measuring thermistor for measuring the temperature of the fluid to be measured is also arranged and connected at the same time as the flow rate sensor at the bottom of the container, so that a temperature measuring thermistor for measuring the temperature of the fluid to be measured can be provided. Since it is not necessary to install the device separately from the flow rate sensor, the device can be easily installed in the pipe or the like.

Further, a convex portion or a concave portion conforming to the shapes of the flow sensor and the temperature measuring thermistor is provided on the bottom of the container, and the flow sensor and the thermistor are fixed on the convex portion or the concave portion. By fixing it to the bottom of the container other than the above, it is possible to mount the flow sensor etc. accurately according to the shape of the convex portion or the concave portion, and ensure the heat insulation state between the flow sensor and the temperature measuring thermistor and the printed circuit board preferably. In addition, it is possible to prevent the product-to-product variation in the heat insulation state.

[Brief description of drawings]

FIG. 1 is a plan view of a flow rate sensor device according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is a cross-sectional view showing how the flow rate sensor is fixed to the recess of the container by soldering.

FIG. 4 is a cross-sectional view showing how the flow rate sensor device of FIG. 1 is attached to a pipe.

5 is a graph illustrating a relationship between an output voltage and a flow rate by the flow rate sensor device of FIG.

FIG. 6 is a sectional view showing a flow rate sensor device according to another embodiment of the present invention.

FIG. 7 is a schematic diagram of a flow sensor device of FIG.
It is a top view which shows a mode that C is connected.

8 is a diagram showing a partial pressure measuring circuit when measuring a flow rate by the flow rate sensor device of FIG.

[Explanation of symbols]

1: Lid, 2: Bottom, 3: Container, 4: Flow rate sensor, 5: Lid terminal, 6: Connector, 7: Printed circuit board, 8: Connector terminal, 11: Thermistor, 12: Recessed part, 13: Recessed part, 14: fluid to be measured, 15: piping, 16: O-ring,
17: Screw, 18: FPC, 24: Glass.

Claims (10)

[Claims] 1. A flow sensor device comprising: a container having a bottom surface in contact with a fluid to be measured; and a thermal type thermistor flow sensor arranged at the bottom of the container. A lid for sealing and closing the container; And a terminal for connecting the inside and the outside of the lid, for making an electrical connection between the flow sensor and the outside of the apparatus, and a connecting means for connecting the flow sensor and the terminal, A flow sensor device in which the container inside the sensor is not sealed with resin. 2. The container and the lid are both made of metal,
The flow rate sensor device according to claim 1, wherein the portions are welded by a resistance welding method or a laser welding method. 3. The connecting means comprises a connector arranged in the container and connecting between the flow rate sensor and the terminal, and the lid and the connector are provided with a terminal of the lid by closing the lid. The flow sensor according to claim 1 or 2, wherein the flow sensor contacts the connector to establish an electrical connection between the flow sensor and the terminal. 4. The connecting means comprises a printed circuit board connecting between the flow rate sensor and the connector, and the connector is directly connected and fixed on the printed circuit board,
The flow rate sensor device according to claim 1, wherein the flow rate sensor and the printed circuit board are connected by wire bonding. 5. The connection means is an FPC that directly connects the flow rate sensor and a terminal of the lid.
3. The connection ends on the flow sensor side of C have the same pitch as the terminals of the flow sensor, and the connection ends on the lid side have the same pitch as the terminals of the lid.
The flow sensor device according to claim 1. 6. The connection means comprises a printed circuit board connected to the flow rate sensor by wire bonding at one end, and an FPC connecting the other end of the printed circuit board and a terminal of the lid. The flow rate sensor device according to claim 1 or 2. 7. The flow rate sensor device according to claim 1, wherein the container has a curved surface shape with a side surface protruding outward. 8. A temperature measuring thermistor arranged at the bottom of the container for measuring the temperature of a fluid to be measured, and the thermistor and the outside of the device are also connected via a connecting means similar to the flow sensor. The flow rate sensor device according to any one of claims 1 to 7, wherein 9. The flow rate sensor is a thin film type flow rate sensor having a base material, a heating element thin film provided on the base material, and a thin film thermistor for measuring the temperature thereof. The flow sensor device according to any one of 1 to 8. 10. The bottom of the container has a convex portion or a concave portion conforming to the shapes of the flow sensor and the temperature measuring thermistor, and the flow sensor and the temperature measuring thermistor are fixed on the convex portion or the concave portion. 9. The flow rate sensor device according to claim 8, wherein