JP2023161655A - Odor sensor module and odor sensor device - Google Patents

Abstract

To provide an odor sensor module and an odor sensor device which are suitable for miniaturization and capable of enhancing efficiency and accuracy of odor substance detection.SOLUTION: A sensor module comprises: a semiconductor integrated circuit with a first circuit at one side among two opposite sides and a second circuit at the other side which is implemented on a print circuit board; a first odor detection element which is implemented on the print circuit board, arranged in the vicinity of one side of the semiconductor integrated circuit, and oscillated by the first circuit; and a second odor detection element which is implemented on the print circuit board, arranged in the vicinity of the other side of the semiconductor integrated circuit, and oscillated by the second circuit. The semiconductor integrated circuit, the first odor detection element, and the second odor detection element are arranged in a flow channel where gas flows and arrayed in a gas flowing direction.SELECTED DRAWING: Figure 1

Description

The present invention relates to an odor sensor module and an odor sensor device for odor measurement.

BACKGROUND ART There are known methods of detecting odorants that utilize resonance frequency fluctuations due to the addition of mass to piezoelectric vibrators such as QCM (Quartz Crystal Microbalance), SAW (Surface Acoustic Wave) resonators, and FBAR (Film Bulk Acoustic Resonators). There are several methods for detecting the resonant frequency: a method of measuring with a measuring device such as a vector network analyzer, a method of measuring with a detection circuit that combines an oscillation circuit and a counter circuit, a method of measuring the resonance frequency by converting the frequency into voltage using a phase shifter and mixer ( For example, Patent Document 1) is known.

Japanese Patent Application Publication No. 2018-115927

In order to modularize a piezoelectric vibrator type odor sensor, it is necessary to measure the frequency on the circuit board, and measurement using an oscillation circuit and a counter circuit is most effective. Since the sensitivity of a piezoelectric vibrator type odor sensor is proportional to the square of the resonance frequency, a piezoelectric vibrator with a high resonance frequency is suitable. The oscillator circuit and counter circuit can be realized using a printed circuit board and discrete components, but since they use multiple components, they tend to be large and require high frequency circuits, so in order to achieve high detection accuracy, it is necessary to change the wiring pattern of the printed circuit board. Consideration must be taken to reduce inductance, and the routing of wiring and thin metal wires is important.
In view of the above circumstances, an object of the present invention is to provide an odor sensor module and an odor sensor device that are suitable for miniaturization and are capable of realizing high efficiency and precision in detecting odor substances. .

The present invention has been made in view of the above-mentioned problems,
Firstly,
A semiconductor integrated circuit mounted on a printed circuit board and having a first circuit formed on one side facing each other and a second circuit formed on the other side side;
a first odor detection element mounted on the printed circuit board, disposed close to one side of the semiconductor integrated circuit, and oscillated by the first circuit;
a second odor detection element mounted on the printed circuit board, disposed close to the other side of the semiconductor integrated circuit, and oscillated by the second circuit;
The semiconductor integrated circuit, the first odor detection element, and the second odor detection element are arranged in a flow path through which gas passes, and lined up along the direction of the gas flow. It is something.
Second,
This problem is solved by making sure that the thicknesses of the semiconductor integrated circuit, the first odor detection element, and the second odor detection element are the same.
Thirdly,
The semiconductor integrated circuit is rectangular in plan view,
The one side and the other side are the short sides of the semiconductor integrated circuit, and the long side of the semiconductor integrated circuit is parallel to the direction of the gas flow.
Fourthly,
The problem is solved by providing the semiconductor integrated circuit with a counter circuit that is provided between the first circuit and the second circuit and counts the frequencies of the first circuit and the second circuit.
Fifth,
a first thin metal wire electrically connecting the semiconductor integrated circuit and the first odor detection element;
a second thin metal wire electrically connecting the semiconductor integrated circuit and the second odor detection element;
This can be solved by having the following.
Sixth,
The problem is solved by providing the first thin metal wire and the second thin metal wire along the direction of the gas flow.
Seventh,
This problem is solved because the mounted components are mounted only in the area outside the long sides on the surface of the printed circuit board.
Eighth,
The odor sensor module is provided in a sensor chamber constituting the flow path, and the flow path is provided with an inlet and an outlet,
The solution is to use an odor sensor device in which a gas transfer device is provided at the inlet or the outlet.
Ninth,
The gas transfer device is a pump, and the sensor chamber is adapted to change to positive or negative pressure.

As described above, according to the present invention, it is possible to provide an odor sensor module and an odor sensor device that are suitable for downsizing and are capable of realizing high efficiency and high precision of odor substance detection.

FIG. 1 is a perspective view of an odor sensor device according to an embodiment of the present invention. FIG. 2 is a plan view of FIG. 1; It is a figure explaining the thickness of a flow path and a chip. FIG. 2 is a perspective view of the odor sensor device. FIG. 2 is an exploded view of the odor sensor device. FIG. 2 is a diagram illustrating a connection between a semiconductor integrated circuit and an odor detection element. FIG. 3 is a cross-sectional view of the odor sensor device. It is a figure explaining a sensor board.

The present invention is an odor sensor module or an odor sensor device using the same, and its features and schematic structure will be described below with reference to FIGS. 1 to 3, and then one embodiment of the sensor device will be described.
Note that the odor sensor will be omitted hereinafter and will also be referred to as a sensor module. Further, the odor detection element and the odor sensor are equivalent.
Based on their principles, odor sensors that detect odors are of the resistive type, which detects changes in the resistance value of a sensitive film, and the vibrator type, which uses a sensitive film attached to the resonant part of a crystal resonator or piezoelectric element to detect changes in the frequency of vibration. There is.
In particular, in the case of a vibrator type, an oscillation circuit and a frequency counter are generally used to detect changes in the oscillation frequency. The present invention has this oscillation circuit inside an IC, and uses this IC to form an odor sensor module.
There are some improvements to be made in doing so, which I will explain.

[About the odor detection element]
As shown in Figures 1 and 2,
Odor measurement requires a sensitive membrane that adsorbs and desorbs odors, and a first odor detection element 10A having this membrane and a second odor detection element 10B for reference are used. For this reason, it is preferable that the two odor detection elements 10A and 10B have substantially the same shape and the same characteristics. These two odor detection elements 10A and 10B having substantially the same shape and the same characteristics are mass-produced using semiconductor technology.
These odor detection elements are arranged in a matrix on a semiconductor wafer, and finally diced and processed into a dice shape (rectangular parallelepiped shape). The individual odor detection elements mass-produced using this wafer are what is referred to here as "substantially the same shape and the same characteristics." Note that it is preferable that they be adjacent within the wafer.
The second odor detection element 10B may have a sensitive film and may be used for odor detection. When used for odor detection, by using a different sensitive film material from that of the first odor detection element 10A, the odor sensor can easily absorb and desorb different odors. At this time, it is preferable that the two odor detection elements 10A and 10B have substantially the same shape and the same characteristics.
These two odor detection elements 10A and 10B are connected to an oscillation circuit. Note that the odor detection elements 10A and 10B are mounted face-up, and a sensitive film is provided on the resonant portion 11 on the front surface, and a wiring L and a bonding pad E that constitute a vibrator are provided around the sensitive film.

Note that the odor detection elements 10A and 10B in FIG. 1 are FBARs (Film Bulk Acoustic Resonators), and electrodes sandwiching a piezoelectric material serving as a resonant portion reach a surrounding bonding pad E via a wiring L. The same applies to crystal oscillators. Further, the SAW is provided with a bonding pad E extending from a pair of comb-teeth electrodes. Both the crystal resonator and the FBAR are provided with a sensitive film in the resonant part. Note that the odor detection elements 10A and 10B are mounted on a printed circuit board 30 in the same manner as the semiconductor integrated circuit 20 described later. The bonding pads E provided around the chip or the wiring L can be substituted for the two bonding pads E for taking in the odor detection elements 10A and 10B. This is because the size of the wiring L is larger than that of the pattern of the semiconductor integrated circuit 20.
Preferably, a bonding pad E is arranged on a side opposite to the short side of the semiconductor integrated circuit 20, and this is preferably used as a bonding pad. However, in the embodiment, bonding is performed on the thick portion of the wiring.
The semiconductor integrated circuit 20 and the odor detection elements 10A and 10B are arranged in a flow path through which gas passes. In FIG. 1, the direction of gas flow is indicated by arrows. The semiconductor integrated circuit 20 and the odor detection elements 10A and 10B are arranged along the direction of this gas flow.

[Semiconductor integrated circuit and mutual interference]
Since the two oscillation circuits A and B oscillate by being connected to the odor detection elements 10A and 10B having the same characteristics, their vibration frequency bands are substantially the same. However, when detecting a smell, the two smell detection elements 10A and 10B oscillate at different frequencies. This is because the odor is adsorbed and desorbed by only one of the odor detection elements 10A and 10B, or the odor is adsorbed and desorbed by both, but the adsorption and desorption characteristics thereof are different. Thus, resonant frequency changes occur due to different mass loads. At this time, depending on the arrangement of the two oscillation circuits A and B and the two odor detection elements 10A and 10B, mutual frequency interference may occur in the two oscillation circuits A and B, causing the problem of oscillation at the same frequency. be. Therefore, countermeasures are required for this purpose.
One of the measures is
In addition to incorporating two oscillation circuits A and B into an integrated circuit, the chip was made elongated. In other words, it is a rectangle in plan view. The first oscillation circuit A is mainly formed on one short side 21 (here, the left side) of this rectangle. Further, a second oscillation circuit B is mainly configured on the other short side 22 (right side). Between the oscillation circuit A and the oscillation circuit B, a frequency counter C is mainly provided which is electrically connected to the two oscillation circuits A and B. These three circuits are generally configured as a pattern of circuit blocks. When a circuit is formed in a certain block area, the function/circuit may not be completed, and necessary circuits may exist in other locations. Therefore, in the text, we used "mainly" and "the oscillation circuit is mainly formed on the short side."

As shown in FIG. 1, the semiconductor integrated circuit 20 is mounted on a printed circuit board 30. If the chip is rectangular in plan view, the frequency counter C is placed in the middle, and the oscillation circuits A and B are placed on both sides, the two oscillation circuits A and B can be separated using the area where the counter C is placed. Since the counter C exists between the two oscillation circuits A and B, leakage current flowing from one oscillation circuit to the semiconductor can be suppressed from reaching the other oscillation circuit and causing noise. Furthermore, since the two oscillation circuits A and B can be separated from each other, noise due to mutual interference can be reduced.
The semiconductor integrated circuit 20 is a compound semiconductor or Si chip, and a diffusion region is formed in an active region on the surface, and a conductive pattern formed on the surface of this region is connected to a transistor etc. formed on the surface. The circuit is installed.
Furthermore, bonding pads connected to the conductive patterns are provided near the short sides 21, 22 and long sides 23, 24 of the semiconductor integrated circuit 20. The bonding pads 25 and 26 on the shorter sides are terminals connected to the odor detection element. The bonding pads 27 and 28 on the long sides are portions into which the power supply and GND of the frequency counter C or the control signal of the counter C are input. The bonding pad E of the odor detection element and the bonding pads 25 and 26 on the short side are connected by a thin metal wire W1. The bonding pads 27 and 28 on the long sides 23 and 24 are connected by a thin metal wire W2.

Note that bonding pads are generally located between the short sides 21, 22 or the long sides 23, 24 of the semiconductor integrated circuit 20 and the circuit block. In another expression, the bonding pads are scattered along the periphery of the semiconductor integrated circuit 20.
As shown in FIG. 2, the semiconductor integrated circuit 20 is arranged so that the long sides 23 and 24 are parallel to the direction of gas flow indicated by the arrows. Odor detection elements 10A and 10B are mounted on the printed circuit board 30 adjacent to one short side 21 and the other short side 22 of the semiconductor integrated circuit 20, and bonding pads 25, 26 are provided.
With this arrangement, since the first oscillation circuit A is located on one short side 21 of the semiconductor integrated circuit 20, the first odor detection element 10A can be placed close to the first oscillation circuit A. Further, the second oscillation circuit B on the other short side 22 side of the semiconductor integrated circuit 20 and the second odor detection element 10B can also be placed close to each other. Therefore, the distance between the four thin metal wires W1 that connect each other can be shortened. Since the thin metal wire W1 is short, the inductance of the thin metal wire can be reduced, and the oscillation circuits A and B can oscillate stably. Furthermore, since the semiconductor integrated circuit 20 incorporating the two oscillation circuits A and B is employed, the mounting size can be reduced when mounted on the printed circuit board 30.

[Printed board]
The printed circuit board 30, which is a mounting board, has a conductive pattern formed on at least its surface and has a mounting area for three semiconductor chips. This conductive pattern includes a pad electrode to which a thin metal wire is connected, an island electrode to be connected to the back surface of a semiconductor chip, and furthermore, a wiring extending integrally with the pad electrode or the island electrode.
The area where the island electrode is located at the center of the printed circuit board 30 is a mounting area for the semiconductor integrated circuit 20, and the semiconductor integrated circuit 20 is soldered thereon. The arrangement portions of the island electrodes provided on the short sides 21 and 22 of the semiconductor integrated circuit 20 are the arrangement regions of the odor detection elements 10A and 10B, and the odor detection elements 10A and 10B are fixed with solder.
A power supply terminal, a ground terminal, a control terminal, etc. are provided on the printed circuit board 30 corresponding to the vicinity of the long side of the semiconductor integrated circuit 20. Mounted components such as a power supply IC and a capacitor to be connected to the semiconductor integrated circuit 20 and wiring for establishing conduction between the mounted components may be provided on the surface of the printed circuit board 30. At this time, if the gas flows in the direction in which the odor detection elements 10A, 10B and the semiconductor integrated circuit 20 are aligned in a straight line, the mounted components are placed on the printed circuit board 30 in an area outside the long side of the semiconductor integrated circuit 20. may only be provided. At this time, the gas flowing toward the odor detection elements 10A and 10B is not obstructed by the mounted components and can be directly applied to the odor detection elements 10A and 10B, thereby preventing deterioration in detection accuracy. Further, by providing wiring only in the region outside the long sides of the semiconductor integrated circuit 20, it is possible to further reduce the amount of gas that gets in the way. The power supply IC connected to the semiconductor integrated circuit 20 is provided on a circuit board separate from the printed circuit board 30 in order to reduce the influence of heat on the odor detection elements 10A and 10B, and the circuit board and the printed circuit board 30 are connected by wiring. The semiconductor integrated circuit 20 may be controlled by making the gate conductive.

As described above, this printed circuit board 30 is provided with the semiconductor integrated circuit 20 and the two odor detection elements 10A and 10B. In this case, the printed circuit board 30 becomes one unit, and gases such as alcohol can be measured. However, since the smell is a mixture of a plurality of components, a plurality of printed circuit boards 30 are arranged. The odor detection elements of each printed circuit board 30 are provided with different sensitive films, and various odors can be determined by examining the frequency changes. (Details are explained in Figure 5.)
This printed circuit board 30 is provided within a sensor chamber 40 that is a flow path. Further, in this embodiment, the surface of the printed circuit board 30 constitutes the inner wall of the sensor chamber 40, and the other side and top surfaces of the internal space are constituted by the inner side walls of the casing 41 or the inner wall of the lid. FIG. 3 shows a solid rectangle 50 including the surface of the printed circuit board 30. As shown in FIG. In other words, this portion is the inner wall of the sensor chamber 40.
In FIG. 7, which will be described later, it can be seen that only the surface of the sensor substrate 102 denoted by reference numeral 102 is exposed to the sensor chamber 40.

[Relationship between the direction of the thin metal wire and the flow path containing odor]
As described above, the printed circuit board 30 on which the semiconductor integrated circuit 20 and the two odor detection elements 10A and 10B at both ends are mounted is housed in the sensor chamber 40. In other words, the printed circuit board 30 is installed within the flow path. In FIG. 1, there is a rectangular parallelepiped indicated by a solid line, and the outermost rectangular parallelepiped is the sensor chamber 40, which is also the flow path. The outside of this sensor chamber 40 becomes a housing 41.
Although the sensor chamber 40 looks wide in the drawing, the vertical height from the surface of the printed circuit board 30 or the surfaces of the odor detection elements 10A and 10B to the ceiling is several mm, and its cross-sectional area is small. The gas flowing through the pump flows through a narrow space. Therefore, the flow rate of the gas transferred by the pump increases. The diagonally upper right side of FIG. 1 is the introduction port 60, and the diagonally lower left side is the discharge port 61. An inlet 60 is provided on the upstream side of the gas flow, and an outlet 61 is provided on the downstream side. Further, a gas transfer device such as a pump is connected to a flow path that communicates with the inlet 60 or the outlet 61 and the outside.
In the embodiment of FIG. 5, gas is supplied to the sensor chamber 40 using a pump 109. In this case, when the pump 109 suctions from the flow path 151 and exhausts the air from the sensor chamber 40 to the flow path 153, the sensor chamber 40 becomes a positive pressure. On the other hand, when gas is supplied to the sensor chamber 40 by suction through the flow path 153 and exhausted through the flow path 151, the sensor chamber 40 becomes under negative pressure. Either way, pressure fluctuations occur through the pump.

On the other hand, the thin metal wire W1 that electrically connects the semiconductor integrated circuit 20 and the first odor detection element 10A and the thin metal wire W1 that electrically connects the semiconductor integrated circuit 20 and the second odor detection element 10B are used to transmit high-frequency signals. , it is necessary to prevent even the slightest movement of the thin metal wire. Wire variations lead to inductance variations.
A high-frequency signal flows through the wire connected to the FBAR, which is the odor detection element, and when the FBAR is viewed from the semiconductor integrated circuit 20 side, it appears as if an inductance is attached to both ends of the resonator. This inductance changes not only with the length and diameter of the wire but also with the degree of deflection, so it is affected by airflow, which affects the oscillation characteristics and causes noise.
In other words, the thin metal wire W1 is provided along the flow direction (indicated by the arrow) of the flow path in order to avoid the influence of airflow and pressure.
On the other hand, a plurality of bonding pads are provided along the two long sides 23 and 24 of the semiconductor integrated circuit 20. A plurality of bonding pads are also provided on the printed circuit board 30 corresponding to this bonding pad, and a thin metal wire W2 connecting these is provided in a direction intersecting the long side, that is, a direction intersecting the flow direction. . This is a signal and power source for driving the IC, and is not a super high frequency signal handled by the thin metal wire W1, and does not require precision.

[Chip thickness of semiconductor integrated circuit and chip thickness of odor detection element]
Semiconductor chips vary in wafer size and wafer thickness depending on the semiconductor manufacturer's process and manufacturing conditions, and the thickness of completed chips also varies.
The semiconductor integrated circuit 20 and the odor detection elements 10A and 10B can all have the same thickness by cutting the back surface of the chips. As a result, the thin metal wire that connects the two can be made shorter.
FIG. 3 shows the first and second odor detection elements 10A, 10B and the semiconductor integrated circuit 20 having the same chip thickness. Reference numeral 30 is a printed circuit board. For example, if the semiconductor integrated circuit 20 is thin and the odor detection elements 10A and 10B are thick, the thin metal wire W1 will need to fall an extra length, and the length of the thin metal wire W1 will become longer. However, if the three chips have substantially the same thickness, each thin metal wire W1 can be made shorter.
Therefore, by making the thin metal wire W1 short, its inductance can be reduced, and the resistance of the thin metal wire W1 to external forces can also be improved.

[size]
Referring to FIG. 1, the dimensions of this embodiment will be explained, and the size of the present invention will be explained. The size of the internal space of the sensor chamber 40 is selected within the range of about 10 to 15 mm on the short side and about 10 to 20 mm on the long side in plan view.
In FIG. 5, since the printed circuit boards 30 are arranged in two rows, the size of the internal space of the sensor chamber 40 is about twice that of FIG. 1, with the short side being about 35 mm and the long side being about 40 mm.
As shown in FIG. 5, the size changes depending on how many printed circuit boards 30 are used and the number of rows.
The height of the sensor chamber 40 is approximately 2 mm to 4 mm from the surface of the sensor substrate 102 or the odor detection element to the ceiling.
Also, the thickness of both chips: 210 μm, the wire length: about 300 μm, the interval between chips: 200 μm, the planar size of the IC chip: 1000 μm×500 μm, and the planar size of the odor sensor: 800 μm×600 μm.
Furthermore, the pump described below can control the flow rate at 0.3 liter/min to 1 liter/min by applying voltage, and usually 0.5 liter/min to 1 liter/min is adopted.
Hereinafter, a specific example, that is, implementation in a casing, will be described with reference to FIGS. 4 to 8.

[Configuration of odor measuring device]
The sensor device 100 has a housing 101, and an odor sensor module 103 is provided inside the housing 101. The odor sensor module 103 includes a sensor substrate 102, a semiconductor integrated circuit 201 mounted on the sensor substrate 102, two odor detection elements 203, a temperature/humidity sensor 104, and the like.
In FIG. 1, one odor sensor module 103 is shown, but here it is composed of four odor sensor modules 103. This is for the purpose of detecting odors, and four types of sensitive membranes are separately provided. The sensor board 102 includes a board on which a temperature/humidity sensor is mounted, and consists of five boards in total.
Below the sensor board 102 is a mounting board 105 that is a motherboard. A sensor control circuit 106 and a power supply circuit 107 mounted on the mounting board, and lead pins 108 for connecting the sensor board 102 and the mounting board 105 are provided. Furthermore, a first pump 109, a second pump 110, and a pump control circuit 111 located above the housing 101 are provided.

Two flow paths are formed in the casing 101 in order to allow gas to flow in and discharge the gas to the outside after passing through the surface of the odor sensor module 103. The outside of this flow path becomes an inlet and an exhaust port.
As shown in FIG. 5, the casing 101 is composed of a plurality of members, and here it is composed of three parts: a first casing 131, a second casing 132, and a third casing 133. These are joined (fitted) to each other by screws 134.
The first housing 131 is a lid that forms the upper wall of the internal space that is the sensor chamber. The second casing 132 is attached with the sensor board 102 described above, and the sensor board 102 and the inner wall of the first casing 131 form an internal space 141 . Furthermore, the third housing 133 constitutes a storage space for the first pump 109.
An internal space 141 is formed by the first casing 131 and the second casing 132. A packing (not shown) is arranged between each housing.
Note that FIG. 5 shows the second housing 132 viewed from above with the first housing 131 and the third housing 133 removed, and the mounted sensor board 102 is visible.

As shown in FIG. 5, the housing 101 is provided with a first flow path 151, a second flow path 152, and a third flow path 153.
The first flow path 151 is provided in the first housing 131 and the third housing 133 from top to bottom, and communicates the internal space 141 with the outside. A first pump 109 is arranged in the middle of the first flow path 151.
The second flow path 152 is provided in the first casing 131 and the third casing 133, and communicates the internal space 141 with the outside. The second pump 110 is arranged in the middle of the second flow path 152.
Portions 151 and 152 visible in FIG. 4 are two introduction ports.
The third flow path 153 is provided on the side wall of the first housing 131 and allows the internal space 141 and the outside of the housing 101 to communicate with each other. The outside of the third flow path 153 is a discharge port.

The sensor board 102 is a printed circuit board made of a resin material and has a conductive pattern such as wiring, and has an odor sensor module 103 and a temperature/humidity sensor 104 mounted thereon. Note that the sensor board 102 is a so-called printed circuit board, and may be a ceramic board or the like.

The sensor board 102 is provided on the mounting board 105 by lead pins 108, as shown in FIG. The sensor control circuit 106 processes output signals of the odor sensor module 103 and communicates with the outside. Power supply circuit 107 supplies driving power to first pump 109 and second pump 110.

The lead pins 108 are arranged between the mounting board 105 and the sensor board 102, separating the sensor board 102 and the mounting board 105, and supporting the sensor board 102 with respect to the mounting board 105. When the mounting board 105 is bonded to the second casing 132, the internal space 141 is sealed by the first casing 131, the second casing 132, and the mounting board 105 serving as a lid.
Further, the sensor board 102 is separated from the mounting board 105 by lead pins 108, and the internal space 141 is divided into a flow path space 144 and a non-flow path space 145.

The first pump 109 is arranged in the first flow path 151 and sends the gas to be measured into the flow path space 144 . Further, the first pump 109 may be arranged outside the first flow path 151. Gas flows into the flow path space 144 from the outside through the first flow path 151 and is discharged from the third flow path 153 . Moreover, the gas delivery direction of the first pump 109 may be reversed.

The second pump 110 is disposed in the second flow path 152 and delivers cleaning gas to the flow path space 144 . Further, the second pump 110 may be placed outside the second flow path 152. The cleaning gas flows into the flow path space 144 from the outside through the second flow path 152 and is discharged from the third flow path 153 .

In this way, the odor sensor device 100 has a separate cleaning mechanism, but the second pump 110 and the second flow path 152 are omitted, and the first pump 109 and the first flow path 151 are used for both cleaning and measurement. Good too. That is, after measuring the odor substance, cleaning can be performed by suctioning the cleaning gas with the first pump 109.

The pump control circuit 111 includes a circuit board 191 and a control element 192 mounted on the circuit board 191, and controls the first pump 109 and the second pump 110. The configuration of the pump control circuit 111 is not particularly limited.

[Operation of odor measuring device]
When odor measurement is started, the first pump 109 is driven, and odor substances contained in the gas are supplied to the surface of each odor sensor module 103 and detected in each odor sensor module 103. Before or after this odor measurement, cleaning of the channel space 144 is performed. During cleaning, the second pump 110 is driven, and the cleaning gas flows through the flow path space 144. The cleaning gas not only takes in the odor substances and moisture adsorbed on the adsorption film and releases them to the outside, but also cleans the odor substances adsorbed on the inner wall of the channel space 144.

[Configuration of odor sensor module]
The odor sensor module 103 is as described in FIGS. 1 to 3, and includes a semiconductor integrated circuit 201, a first odor detection element 202, a second odor detection element 203, a first thin metal wire 204, and a second thin metal wire. 205.
As shown in FIG. 6, the semiconductor integrated circuit 201 is rectangular in plan view, and connection pads 215 and 216 with the FBAR are provided on the short sides 211 and 212 thereof. Further, since an oscillation circuit is built in each of the two short sides of the semiconductor integrated circuit 201 and a counter circuit is provided between them, the distance between the oscillation circuits is set to be long. This prevents mutual interference and prevents oscillation from stopping due to noise intrusion. Moreover, the inductance generated by the connection of the FBAR with thin metal wires is also affected.

As described above, the oscillation circuit within the semiconductor integrated circuit 201 oscillates, including the FBAR. Therefore, the inductance of the electrically connected thin metal wires 204 and 205 has an influence. Therefore, in order to make the oscillation characteristics of the two oscillation circuits the same and to suppress the stoppage of oscillation, it is preferable that the lengths of the thin metal wires are as short as possible, and furthermore, that they are substantially the same length.
Therefore, it is important to make the chip thickness of the odor detection elements 202 and 203 the same as that of the semiconductor integrated circuit 201. By keeping the thickness the same, the loop length of the thin metal wire can be minimized. Semiconductor chips include ICs, discrete chips, and the like, and the thickness of the chips varies from company to company. Therefore, it is important to grind at least one of the chips to make the thickness of the three chips the same. Furthermore, since this thin metal wire is exposed to the flow path, making it as short as possible has the advantage of increasing its strength and reducing corrosion and mechanical damage.
Furthermore, by extending the thin metal wires 204 and 205 in the direction along the gas flow, the influence of the air flow can be suppressed and measurement accuracy can be improved, similarly to the thin metal wire W1 in FIG.

10A, 10B: Odor detection element 20: Semiconductor integrated circuits 21, 22: Short side 30: Printed circuit board 40: Sensor chamber 60: Inlet 61: Outlet
W1: thin metal wire 100: odor sensor device 101: housing 102: sensor board 103: odor sensor module 104: temperature/humidity sensor 105: mounting board 106: sensor control circuit 107: power supply circuit 108: lead pin 109: first pump 110: Second pump 111: Pump control circuit 201: Semiconductor integrated circuits 202, 203: Odor detection elements 204, 205: Fine metal wire

Claims (9)

A semiconductor integrated circuit mounted on a printed circuit board and having a first circuit formed on one side facing each other and a second circuit formed on the other side side;
a first odor detection element mounted on the printed circuit board, disposed close to one side of the semiconductor integrated circuit, and oscillated by the first circuit;
a second odor detection element mounted on the printed circuit board, disposed close to the other side of the semiconductor integrated circuit, and oscillated by the second circuit;
The semiconductor integrated circuit, the first odor detection element, and the second odor detection element are arranged in a flow path through which gas passes, and are lined up along the flow direction of the gas. The odor sensor module according to claim 1, wherein the semiconductor integrated circuit, the first odor detection element, and the second odor detection element have the same thickness. The semiconductor integrated circuit is rectangular in plan view,
3. The odor sensor module according to claim 1, wherein the one side and the other side are short sides of the semiconductor integrated circuit, and the long side of the semiconductor integrated circuit is parallel to the direction of the gas flow. The odor sensor module according to claim 1 or 2, wherein the semiconductor integrated circuit includes a counter circuit provided between the first circuit and the second circuit and counting frequencies of the first circuit and the second circuit. . a first thin metal wire electrically connecting the semiconductor integrated circuit and the first odor detection element;
a second thin metal wire electrically connecting the semiconductor integrated circuit and the second odor detection element;
The odor sensor module according to claim 1 or 2, comprising: The odor sensor module according to claim 5, wherein the first thin metal wire and the second thin metal wire are provided along the direction of the gas flow. 4. The odor sensor module according to claim 3, wherein the mounted component is mounted only in an area outside the long side on the surface of the printed circuit board. The odor sensor module according to claim 1 is provided in a sensor chamber forming the flow path, and the flow path is provided with an inlet and an outlet,
A gas transfer device is provided at the inlet or the outlet. The odor sensor device. The odor sensor device according to claim 8, wherein the gas transfer device is a pump, and the sensor chamber has a positive pressure or a negative pressure.

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