JP3328547B2 - Thermal air flow sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal air flow sensor, and more particularly to a thermal air flow sensor suitable for measuring an intake air amount of an internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, as an air flow sensor which is provided in an electronic control fuel injection device of an internal combustion engine of an automobile or the like and measures an intake air amount, a thermal air flow sensor has become mainstream since it can directly detect a mass air amount. I have. Among them, an air flow sensor manufactured by a semiconductor micromachining technology has attracted particular attention because it can reduce cost and can be driven with low power.

The technology of such a conventional thermal air flow sensor using a semiconductor substrate is disclosed in, for example, Japanese Patent Application Laid-Open No. 7-1745.
No. 99 is disclosed. FIG.
FIG. 13 shows a cross section of the conventional thermal air flow sensor shown in FIG.
It was shown to. In FIG. 13, the semiconductor sensor element 2 includes a heating resistor 3 formed on a semiconductor substrate, a temperature measuring resistor 24, and a cavity 5 for forming a diaphragm 6 for thermal insulation. 10c is a lead (output terminal) for connecting to an external circuit, 22 is a semiconductor sensor element 2 and a lead 1
Gold bumps connecting 0c, 7 are molding materials, and 2
Reference numeral 3 denotes a dam resin film for preventing the protrusion of the molding material.

[0004]

However, in the above prior art, an example is described in which leads for connecting a semiconductor sensor element and an external circuit are molded.
The mounting structure of the semiconductor sensor element is not sufficiently considered for the flow of the air flow to be measured, the air flow measurement accuracy of the flow sensor is not sufficient, and the circuit for measuring the air flow is an external circuit. There is a problem that the number of parts is increased and the cost is high because the sensor element is configured differently from the sensor element.

That is, in the conventional example shown in FIG. 13, the air flow to be measured flows parallel to the semiconductor sensor element 2 (in the direction perpendicular to the drawing). Turbulence is generated in the air flow on the lower surface of the device, and signal noise is generated due to temperature fluctuations of the heating resistor 3 on the diaphragm 6. Further, since no consideration is given to radio wave interference, the signal noise also increases from this point. There is a problem. In addition, since the circuit for measuring the air flow rate is an external circuit and is configured separately from the semiconductor sensor element, there is a problem that the number of parts is increased and the cost is high. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a thermal type air flow sensor which can reduce signal noise and reduce cost.

[0006]

A thermal air flow sensor that achieves the above object has a measuring part including a temperature measuring resistor formed on a semiconductor substrate and a heating resistor formed on a cavity provided in the semiconductor substrate. A semiconductor sensor element having a control circuit for executing a control for applying a heating current to the heating resistor so as to increase the temperature of the temperature measuring resistor by a predetermined temperature to obtain an air flow signal representing an air flow rate; A terminal for outputting the air flow signal to the outside, and supporting at least the semiconductor sensor element of the semiconductor sensor element or the control circuit while closing the cavity with a terminal material forming the terminal. is there.

[0007] The terminal material is the same as the terminal material portion corresponding to the measurement site of the semiconductor sensor element and the output terminal site of the terminal.
It is preferable that the semiconductor sensor element and the control circuit are integrally coated with an insulator made of an electrical insulating material. Further, it is preferable that the insulator is a mold material that can be integrally molded.

According to the present invention, the signal noise is reduced by supporting the semiconductor sensor element while closing the cavity with the terminal material forming the terminal, and such a closed body and a support are integrated. As a result, the number of parts is reduced, and the cost is reduced.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a plan view showing a thermal air flow sensor according to a first embodiment of the present invention.
FIG. 2 is a diagram showing a cross section taken along line AA ′ of the thermal air flow sensor of FIG. 1 and 2, a thermal air flow sensor 1
The semiconductor device includes a semiconductor sensor element 2, a molding material 7, a control circuit 11, a lead 10 (also referred to as a lead frame) as a terminal material formed of the same material, and a connection wire 12.

The semiconductor sensor element 2 includes a cavity 5 formed from the lower surface of a semiconductor substrate made of silicon or the like by anisotropic etching to a boundary surface of a diaphragm 6 made of an electric insulating film, and a cavity 5, that is, on the diaphragm 6. A configuration including a heating resistor 4 formed, a temperature measuring resistor 3 formed at the tip of a semiconductor substrate for measuring air temperature, and a wiring connection terminal 9 connecting each resistor to an external circuit or the like. Is done. Further, the control circuit 11 executes a control for supplying a heating current to the heating resistor 4 so as to increase the temperature of the temperature measuring resistor 3 by a predetermined temperature to obtain an air flow signal indicating the air flow. .

On the other hand, the first lead 10f is a lead 10e (at least one end face) for positioning and supporting the semiconductor sensor element 2 while closing the cavity 5 from the lower surface of the semiconductor substrate.
And leads 10d (both sides). That is, the first lead 10f is a closing member and a supporting member of the semiconductor sensor element 2. In addition, the second lead 10a
The third lead 10b relays the circuit connection between the semiconductor sensor element 2 and the control circuit 11 (that is, a connection body).
Are those that support the control circuit 11 (that is, the control circuit 1
1 support). And the fourth lead 10c is
A terminal (that is, a connection body) that outputs an air flow signal from the control circuit 11 to the outside. Further, the connection wire 12a
Is a circuit connection between the semiconductor sensor element 2 and the second lead 10a, a connection wire 12b is a circuit connection between the second lead 10a and the control circuit 11, and a connection wire 12c is a
A circuit connection is made between the first and fourth leads 10c.

A molding material 7 as an insulator is made of an electric insulating material that can be integrally molded such as an epoxy resin, and is used for the semiconductor sensor element 2 including a heating resistor 4 and a temperature measuring resistor 3 that sense an air flow. Excluding the measurement site, the terminal material site facing the measurement site and closing the cavity, and the terminal material site corresponding to the fourth lead 10c as the output terminal site, excluding the measurement site of the semiconductor sensor element 2,
The control circuit 11, the leads 10a, 10b, 10c, 10f and the connecting wires 12a, 12b, 12c are integrally covered by molding.

Here, the semiconductor sensor element 2 is obtained as follows. First, silicon dioxide, silicon nitride, or the like as a diaphragm 6 made of an electrical insulator is thermally oxidized or C-coated on a silicon semiconductor substrate to a thickness of about 0.5 μm.
It is formed by a method such as VD. Furthermore, a metal thin film such as platinum or a semiconductor thin film such as polycrystalline silicon (Si) or polycrystalline silicon carbide (SiC) is sputtered as the heating resistor 4 and the temperature measuring resistor 3 to a thickness of about 0.1 to 1 micron. Alternatively, after forming by a method such as CVD, a resist is formed in a predetermined shape by a known photolithography technique, and then the heating resistor 4 and the temperature measuring resistor 3 are patterned by a method such as reactive ion etching. Next, after the wiring connection terminals 9 are formed of aluminum, gold, or the like, an electric insulator is formed to a thickness of about 0.5 μm in the same manner as described above, using a portion other than the wiring connection terminals 9 as a protective film. Finally, a cavity 5 is formed from the back surface of the silicon semiconductor substrate by anisotropic etching using silicon dioxide or the like as a mask material, and the semiconductor sensor element 2 is obtained by cutting into a chip.

Next, the operation of the embodiment of the present invention will be described with reference to FIG. FIG. 3 is a diagram showing an electric circuit of one embodiment according to the present invention. FIG. 2 is a circuit diagram of the thermal air flow sensor 1 showing each resistor of the semiconductor sensor element 2 and a control circuit 11. In the figure, 16 is a power supply, 15 is a transistor for passing a heating current to the heating resistor 4, 17a, 17b, 17c
Is a resistor, 14 is an input circuit including an A / D converter and the like, and D /
An arithmetic circuit comprising an output circuit including an A converter and the like and a CPU and a memory circuit for performing arithmetic processing and the like;
Consists of a semiconductor integrated circuit in which circuits surrounded by broken lines in the figure are integrated.

Here, the heating resistor 4, the temperature measuring resistor 3,
The voltage of the intermediate terminals B and C of the bridge circuit composed of the resistors 17a and 17b is input to the arithmetic circuit 14, and the temperature of the heating resistor 4 is a certain value higher than the temperature of the temperature measuring resistor 3 corresponding to the air temperature.
(For example, ΔTh = 150 ° C.)
Is set and controlled by the arithmetic circuit 14. If the temperature of the heating resistor 4 is lower than the set value, the arithmetic circuit 1
The transistor 16 is turned on by the output of the heat-generating resistor 4
When the heating current flows and becomes higher than the set temperature, the transistor 16 is turned off so that the transistor 16 is controlled to be constant at the set value. Based on the principle that the heating current increases due to the cooling of the heating resistor 4 as the air flow increases, the air flow rate (Q) is measured from the heating current value (corresponding to the potential C of the resistor 17b) flowing through the heating resistor 4 I do.

In this embodiment, the direct heating system in which only the heating resistor 4 and the temperature measuring resistor 3 are used as the semiconductor sensor element 2 has been described. As a temperature difference detection method with a body placed,
A configuration in which a pair of heating resistors is arranged upstream and downstream to detect the air flow direction and the flow rate may be used, and any configuration having at least the heating resistor 4 and the temperature measuring resistor 3 may be used.
The heating resistor 4 and the temperature measuring resistor 3 are made of polycrystalline silicon.
(Si), when the linearity of the resistance-temperature function is not sufficient like a semiconductor thin film such as polycrystalline silicon carbide (SiC),
If the resistance-temperature function of the semiconductor thin film and the flow rate correction data are stored in advance in the memory of the arithmetic circuit 14, the arithmetic circuit 1
By performing arithmetic processing by the CPU of No. 4, high precision measurement of the air flow rate (Q) becomes possible.

FIG. 4 is a sectional view showing a sensor mounting structure according to an embodiment of the present invention. FIG. 2 is a sectional view showing an embodiment of a thermal air flow sensor on which the thermal air flow sensor 1 of FIG. 1 is mounted. FIG. 1 is a cross-sectional view illustrating an example of a thermal air flow sensor 1 mounted in an intake passage of an internal combustion engine of an automobile or the like. As shown in the figure, the thermal air flow sensor 1 is configured such that the heating resistor 4 and the temperature measuring resistor 3 of the semiconductor sensor element 2 are exposed to the air flow to be measured in the sub-passage 19 inside the intake passage 18. Be placed. The measured air flow signal (Q) is sent from the lead 10c of the thermal air flow sensor 1 to the engine control circuit.

Next, an assembling process of the thermal air flow sensor 1 according to the first embodiment of the present invention shown in FIG. 1 will be described.
FIG. 5 is a diagram showing an assembling process of the thermal air flow sensor according to the first embodiment. In the process shown in FIG. 5A, the lead 10 (10a, 10b,
0c, 10d, 10e, 10f) are formed. The lead 10 includes a first lead 10 f having positioning leads 10 e and 10 d provided for supporting and positioning the semiconductor sensor element 2, and a second lead 10 for relaying a circuit connection between the semiconductor sensor element 2 and the control circuit 11. , A third lead 10b for supporting the control circuit 11, and a fourth lead 10c for outputting the output signal of the control circuit 11 to the outside are integrated with the outer peripheral frame.

The positioning leads 10e and 10d are perpendicular to the drawing so that the leads 10f on a plane are stamped after patterning or die cutting to position one end surface and both side surfaces of the semiconductor sensor element 2. It is formed by bending in the direction. That is, another feature of the thermal air flow sensor according to the present invention is that the first lead 10f for supporting the semiconductor sensor element is provided on at least one end surface or both side surfaces of the semiconductor sensor element for positioning the semiconductor sensor element. Positioning leads 10 arranged facing each other
e, 10d.

FIG. 5A shows one lead 10 of the thermal air flow sensor 1, but if a plurality of leads 10 are repeatedly connected to one material, a plurality of leads 10 may be provided. Batch thermal processing of the individual thermal air flow sensors 1 can be performed, productivity of the assembling process can be further improved, and the cost of the thermal air flow sensor can be reduced.

In the step shown in FIG. 5B, the semiconductor sensor element 2 and the control circuit 11 are arranged at predetermined positions on the first lead 10f and the third lead 10b. A connection wire 12a for connecting the lead 10a to the circuit, a connection wire 12b for connecting the second lead 10a to the control circuit 11, and a connection wire 12c for connecting the control circuit 11 to the fourth lead 10c. Is wire-bonded with a wire such as aluminum or gold.

In FIG. 5 (c), except for the measurement site including the resistors 3 and 4 for sensing the air flow of the semiconductor sensor element 2 and the output terminal site (external connection portion) of the fourth lead 10c, Semiconductor sensor element 2, control circuit 11, leads 10f, 10
The a, 10b, 10c and the connection wires 12a, 12b, 12c are integrally formed and covered with a molding material 7 such as an epoxy resin using a predetermined mold. Finally, in the step of FIG. 5D, the outer peripheral frame portion of the lead 10 is cut off, and the thermal air flow sensor 1 is obtained. Therefore, the molding material 7 that can be integrally molded covers each component part integrally and by a molding process, so that each component part is tightly integrated so as not to be scattered. In other words, it can be said that the terminal material forming the terminal is used for the closing body, the support, and the like, and is integrated by molding, thereby reducing the number of parts and leading to cost reduction.

In the thermal air flow sensor 1 of the present invention having the above-described structure, as shown in FIGS. 1 and 2, the cavity 5 below the diaphragm 6 of the semiconductor sensor element 2 is closed by the lead 10f. Because they are not directly exposed to stream 13
The occurrence of turbulence in the cavity as in the conventional example is prevented, and the thermal fluctuation of the heating resistor 4 is reduced, so that the noise of the output signal is reduced. Further, in the conventional example, the control circuit 11 has a configuration different from that of the thermal air flow sensor 1, but in the present invention, the control circuit 11 is
In addition, since the lead 10 and the molding material 7 are integrally formed, the number of parts can be reduced, and the productivity of the assembling process is improved, so that the cost can be reduced.

FIG. 6 is a sectional view showing a thermal air flow sensor according to a second embodiment of the present invention. 2 shows a cross section of a thermal air flow sensor 1 according to a second embodiment of the present invention. The difference of the second embodiment shown in FIG. 6 from the first embodiment is that the leads 10a to 10f formed of the terminal material are integrated on the insulating substrate 8.
By integrating the leads 10a, 10b, 10c, 10f on the insulating substrate 8, the strength of the leads can be increased. Also,
The lead 10f is bent at the tip of the insulating substrate 8 to form the concave lead 10g (a part of the lead 10f), thereby positioning the semiconductor sensor element 2 on the side surface in four directions (front-rear, left-right directions in the figure). Therefore, the positioning operation can be performed reliably and easily. That is, another feature of the thermal air flow sensor according to the present invention is that the lead 10 (10a, 10b, 10c,
10f) is integrated on the insulating substrate 8.

FIG. 7 is a diagram showing an assembling process of the thermal air flow sensor according to the second embodiment. FIGS. 7A, 7B, and 7C show an assembly process of the thermal air flow sensor 1 according to the second embodiment. In the step shown in FIG. 7A, the first lead 10f (including the leads 10e, 10d, 10g) supporting the semiconductor sensor element 2 while closing the cavity 5, the lead 10a of the connector, the control circuit
10b supporting 11 and fourth lead 1 as terminal
0c is integrated on the insulating substrate 8 as described above.
The insulating substrate 8 is made of a hard material such as alumina or a flexible material such as a resin. The leads 10 on the substrate are patterned into a predetermined shape, and are then formed and integrated. 7B and 7C, as in the first embodiment, after the semiconductor sensor element 2 and the control circuit 11 are arranged at predetermined positions and the connection wires 12a, 12b, and 12c are connected, The molding material 7 is integrally molded using a predetermined mold. The description of the step of removing the outer peripheral frame of the lead 10 is omitted.

FIG. 8 is a sectional view showing a thermal air flow sensor according to a third embodiment of the present invention. FIG.
It is a figure showing an assembly process of a thermal type air flow sensor of a 3rd example. FIG. 8 shows a cross section of the thermal air flow sensor 1 according to the third embodiment of the present invention, and FIGS. 9 (a), 9 (b) and 9 (c) show an assembling process. The difference between the third embodiment and the first embodiment shown in FIGS. 1 and 2 is that the control circuit 11 is a semiconductor chip composed of a semiconductor integrated circuit in the first embodiment. In the third embodiment, the insulating substrate 20 and the electrical components 11a and 11 such as a thick film wiring and a resistor pattern disposed on the substrate, a semiconductor chip composed of a semiconductor integrated circuit, and a chip capacitor are provided.
b, 11c, and the first lead 10f (including the lead 10e, 10d, 10g) and the fourth lead 10c of the lead 10 are integrated on the insulating substrate 8, Between the first lead 10f and the fourth lead 10c,
That is, the control circuit 11 is fixed.

In the step shown in FIG. 9A, the first leads 10f (including the leads 10e, 10d, 10g) supporting the semiconductor sensor element 2 while closing the cavity 5 and formed as a terminal are formed from the terminal material. The fourth lead 10c is connected to the insulating substrate 8
Integrated above. 9 (b) and 9 (c), the insulating substrate 20 and the thick film wiring, the resistance pattern, and the like disposed between the lead 10f and the lead 10c on the insulating substrate 8 are arranged.
After the control circuit including the electric components 11a, 11b, 11c, etc., such as a semiconductor chip and a chip capacitor, which are composed of a semiconductor integrated circuit, are arranged, the connection wires 12a, 12b are connected. Molded. The description of the step of removing the outer peripheral frame of the lead 10 is omitted.

In the thermal air flow sensor 1 according to the third embodiment, which is configured as described above, the control circuit includes the thick film wiring, the resistance pattern, and the electric components 11a, 11b, and 11c on the insulating substrate 20. , Electric parts 1
1a, 11b, and 11c can be replaced as appropriate for each application, increasing flexibility and having the advantage that circuit adjustment by resistance trimming can be performed more precisely by using a resistor pattern as an adjustment resistor. is there. That is, another characteristic of the thermal air flow sensor according to the present invention is that the control circuit 11 is configured such that the insulating substrate and the semiconductor chip including the thick film wiring, the resistor pattern and the semiconductor integrated circuit arranged on the substrate, the semiconductor chip and the chip capacitor, etc. And electrical components.

FIG. 10 is a view showing a process of assembling a thermal air flow sensor according to a fourth embodiment of the present invention. FIG.
(a), (b), (c) and (d) show an assembly process of a thermal air flow sensor 1 according to a fourth embodiment of the present invention. The fourth embodiment has the same configuration as the lead 10 (that is, the lead frame) of the second embodiment shown in FIGS. 6 and 7, and the semiconductor sensor element 2 and the control circuit 11 And the connection wires 12a, 12b, 12c are connected. In FIG. 10C, a sub-passage member 19a having a predetermined shape is formed to form a sub-passage 19 for introducing the air flow to be measured into each of the resistors 3 and 4 for sensing the air flow of the semiconductor sensor element 2. In FIG. 10 (d), the semiconductor sensor element 2, the control circuit 11, and the lead 10 are integrally formed with the molding material 7 including the sub-passage constituting member 19 a.

The thermal air flow sensor 1 constructed as described above
Then, the semiconductor sensor element 2, the control circuit 11, and the lead 10 are molded by the molding material 7 including the sub-passage constituting member 19a.
Is integrally molded, the number of parts can be reduced, and the productivity of the assembling process can be improved, so that the cost can be reduced. Here, the auxiliary passage component member 19a has a rectangular cross section in FIG. 10 (c), but any shape can be used, such as a circular cross section, a structure for converging the air flow, or a U-shaped folded structure. It is. That is, another feature of the thermal air flow sensor according to the present invention is that the sub-passage constituting member 19a for exposing to the air flow to be measured is provided with each of the resistors 3 and 4 for sensing the air flow of the semiconductor sensor element 2 and its associated components. First Lead 1
0f together with the molding material 7 during molding.

FIG. 11 is a sectional view showing a thermal air flow sensor according to a fifth embodiment of the present invention. FIG. 12 is a sectional view showing a thermal air flow sensor according to a sixth embodiment of the present invention. The cross sections of the thermal air flow sensor 1 according to the fifth and sixth embodiments of the present invention are respectively shown. The thermal air flow sensor 1 according to the fifth and sixth embodiments further reduces electromagnetic noise such as radio wave interference and improves the signal-to-noise ratio. The molding material 7 such as an epoxy resin alone is an insulating material, and it is difficult to sufficiently shield it from external electromagnetic noise. This is a problem particularly in a severe environment such as when applied to an air flow sensor such as an automobile. Therefore, the shield body is integrally formed with the molding material 7 and held.
Since integral molding is possible, it is effective in terms of workability and strength. That is, another feature of the thermal air flow sensor according to the present invention is that the molding material 7 as an insulator includes the conductor lead 10h or the conductor 21 as a shield for electromagnetically shielding the control circuit 11. It is in.

In the fifth embodiment shown in FIG.
The semiconductor sensor element 2, the control circuit 11, and a conductor lead 10h are arranged below the wiring connection part as an electromagnetic shield for preventing electric wave interference of the wiring connection part, and are integrally formed at the time of molding. Conductor lead 10h
Is disposed as a lower layer of the insulating substrate 8 so as to sufficiently cover the control circuit 11 and the wiring connection portion, is finally grounded via a terminal not shown, and serves as a support for the semiconductor sensor element 2. Is also working. With such a configuration, the semiconductor sensor element 2, the control circuit 11, and the wiring connection portion are covered with the conductor lead 10h at the lower portion thereof, and are electromagnetically shielded from the outside.
The signal to noise ratio is improved.

In the sixth embodiment shown in FIG. 12, a conductor 21 is disposed above the control circuit 11 and the wiring connection portion as an electromagnetic shield, and is integrally formed at the time of molding. In such a configuration, similarly to the fifth embodiment in FIG.
Since the upper part of the control circuit 11 and the wiring connection part are closely covered by the conductor 21, they are electromagnetically shielded from the outside and the signal-to-noise ratio is improved.

In the fifth and sixth embodiments, the control circuit 1
1 and the wiring connection portion are defined by the conductor lead 10h and the conductor 21.
The electromagnetic shielding is performed at the upper part and the lower part. However, the electromagnetic shielding of both the upper and lower parts naturally has the same effect. Further, if a filter circuit for reducing electromagnetic noise is incorporated in the control circuit 11 with respect to the electromagnetic shield such as the conductor lead 10h and the conductor 21, the signal-to-noise ratio is further improved. improves.

[0035]

According to the present invention, (1) at least the heating resistor 4 and the temperature measuring resistor 3 are provided on the semiconductor substrate with the electric insulating film interposed therebetween.
Sensor element 2 having wiring connection terminals 9 formed thereon
And a control circuit 1 for measuring the air flow rate by supplying a heating current to the heating resistor 4 at a predetermined temperature higher than the temperature of the temperature measuring resistor 3.
1 and a lead 10 for outputting a measured air flow signal to the outside. At least, except for the resistor parts 3 and 4 for sensing the air flow of the semiconductor sensor element 2 and the external connection part of the lead 10, Semiconductor sensor element 2, control circuit 11
And the leads 10 are covered by molding. (2) Also, the leads 10 are arranged so as to face at least one end face and both side faces of the semiconductor sensor element in order to support and position at least the semiconductor sensor element. The control circuit 11 comprises a first lead 10f on which positioning leads 10e and 10d are arranged and a fourth lead 10c for outputting an output signal to the outside. A substrate and a thick film wiring and a resistance pattern arranged on the substrate, a semiconductor chip composed of a semiconductor integrated circuit, an electric component such as a chip capacitor, and (3) a sub-passage 19a for guiding an air flow to be measured; To prevent electromagnetic interference in the electromagnetic shielding conductors 10h, 21 disposed in the upper or lower part of the control circuit or in the control circuit. By incorporating a filter circuit and integrally molding at the time of the molding, the cavity 5 which is a problem in the conventional example is covered with the first lead 10f, so that the air flow is not disturbed and the electromagnetic shields 10h and 21 are added. As a result, a thermal air flow sensor with reduced signal noise and a reduced number of components due to the integrated control circuit can be provided.

[Brief description of the drawings]

FIG. 1 is a plan view showing a thermal air flow sensor according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a cross section taken along the line AA ′ of the thermal air flow sensor of FIG. 1;

FIG. 3 is a diagram showing an electric circuit of one embodiment according to the present invention.

FIG. 4 is a sectional view showing a sensor mounting structure according to an embodiment of the present invention.

FIG. 5 is a diagram showing an assembly process of the thermal air flow sensor according to the first embodiment.

FIG. 6 is a sectional view showing a thermal air flow sensor according to a second embodiment of the present invention.

FIG. 7 is a diagram showing an assembling process of the thermal air flow sensor according to the second embodiment.

FIG. 8 is a sectional view showing a thermal air flow sensor according to a third embodiment of the present invention.

FIG. 9 is a diagram showing an assembling process of the thermal air flow sensor according to the third embodiment.

FIG. 10 is a view showing an assembling process of a thermal air flow sensor according to a fourth embodiment of the present invention.

FIG. 11 is a sectional view showing a thermal air flow sensor according to a fifth embodiment of the present invention.

FIG. 12 is a sectional view showing a thermal air flow sensor according to a sixth embodiment of the present invention.

FIG. 13 is a sectional view showing a conventional thermal air flow sensor.

[Explanation of symbols]

1. Thermal air flow sensor 2: Semiconductor sensor element 3,
Reference numeral 24: resistance temperature detector, 4: heating resistor, 5: cavity, 6: diaphragm, 7: molding material, 8, 20: insulating substrate, 9
... Wiring connection terminals, 10, 10a, 10b, 10c, 10d, 10e, 10f, 10g ... Leads, 10h ... Conductor leads, 11 ... Control circuits, 11a, 11b, 11c
... Electrical parts, 12,12a, 12b, 12c ... Connection wires, 13 ... Air flow, 14 ... Operation circuit, 15 ... Transistor, 16 ... Power supply, 17a, 17b, 17c ... Resistance, 18 ... Intake passage, 19 ... Sub passage , 19a: Sub-passage constituent member, 21: Conductor, 22: Gold bump, 23: Dam resin film.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-9-26343 (JP, A) JP-A 8-292224 (JP, A) JP-A 7-263888 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) G01F 1/68-1/699

Claims (2)

(57) [Claims] A heating resistor on a semiconductor substrate having a cavity and a temperature measuring resistor for measuring a temperature of air for measuring a flow rate;
A control circuit for supplying a heating current to the heating resistor to obtain an air flow signal so as to be higher by a predetermined temperature than the temperature of the temperature measuring resistor; A heating resistor formed in the hollow portion of the semiconductor substrate via an electric insulating film, a temperature measuring resistor formed in a portion of the semiconductor substrate outside the hollow portion, and a heating resistor arranged so as to cover the hollow portion. An obstruction support lead having one end face and both side faces for positioning a sensor section comprising the temperature measuring resistor and the heating resistor, a connector for outputting an air flow signal obtained by the control circuit, A connection unit connected from the sensor unit to the control circuit, a portion including the control circuit between the end of the connection unit that outputs the air flow signal obtained in the control circuit and the end of the sensor unit and Integrally molded Thermal air flow sensor according to claim and. 2. A heating resistor and a temperature measuring resistor for measuring a temperature of air for measuring a flow rate on a semiconductor substrate having a cavity;
A control circuit that supplies a heating current to the heating resistor to obtain an air flow signal so as to be higher by a predetermined temperature than the temperature of the temperature measuring resistor. A sensor section comprising a heating resistor formed on the cavity through an electrical insulating film, a temperature measuring resistor formed on a portion of the semiconductor substrate outside the cavity, and closing the cavity. And a closed support lead having one end surface and both side surfaces for positioning a sensor portion comprising the temperature measuring resistor and the heating resistor, and the positioning member including the heating resistor and the temperature measuring resistor. A connection unit for arranging the sensor unit in the sub-passage provided in the intake passage and outputting an air flow signal obtained by the control circuit; and a connection unit for connecting the sensor unit and the control circuit. And obtained by the control circuit. Thermal type air flow sensor being characterized in that integrally molded include matching and the control circuit between the ends of said connecting member end the sensor unit which outputs an air flow rate signal.