JP5720999B2 - Infrared sensor and circuit board having the same - Google Patents

Description

  The present invention relates to an infrared sensor that detects infrared rays from a measurement object and measures the temperature or the like of the measurement object, and a circuit board including the infrared sensor.

Conventionally, an infrared sensor is used as a temperature sensor that detects the temperature of an object to be measured by detecting infrared rays radiated from the object to be measured in a non-contact manner.
For example, in Patent Document 1, a resin film installed on a holding body, an infrared detection thermal element that is provided on the resin film and detects infrared rays through a light guide portion of the holding body, and a light shielding state is provided on the resin film. An infrared sensor including a temperature-compensating thermosensitive element that detects the temperature of the holder is proposed. In this infrared sensor, an infrared absorption film is formed on the inner side surface of the light guide section, and an infrared absorption material such as carbon black is included in the resin film to enhance infrared absorption.

  Patent Document 2 discloses a thermal sensing element for detecting infrared rays, a thermal sensing element for temperature compensation, a resin film for tightly fixing them, a thermal sensing element for detecting infrared rays on the infrared incident window side, and a shield for shielding infrared rays. And an infrared detector including a case having a frame body in which a temperature-compensating thermosensitive element is disposed on the part side. In this infrared detector, an infrared absorbing material such as carbon black is included in the resin film to enhance infrared absorption, and heat conduction is performed to eliminate the thermal gradient between the infrared detecting thermal element and the temperature compensating thermal element. The frame is made of a good material. In addition, a pine needle type thermistor in which a lead wire is connected to the thermistor is employed in the infrared detecting thermal element and the temperature compensating thermal element.

In these infrared sensors of Patent Documents 1 and 2, a structure in which an infrared absorbing material such as carbon black is contained in a resin film and one heat sensitive element side is shielded for temperature compensation is used. The heat conduction of the resin film is high, and there is a disadvantage that a temperature difference is hardly generated between the thermal sensing elements for infrared detection and temperature compensation. Also, in order to increase the temperature difference between these thermal elements, it is necessary to increase the distance between the thermal elements, which increases the overall shape and makes it difficult to reduce the size. Furthermore, since it is necessary to provide the case itself with a structure that shields the temperature-compensating thermal element, the cost is increased.
Moreover, in patent document 2, since the frame body with favorable heat conductivity is employ | adopted, the heat from an infrared rays absorption film is also thermally radiated and there exists a problem that a sensitivity deteriorates. In addition, because of the pine needle type to which the lead wire is connected, heat conduction occurs between the thermistor and the lead wire.
In addition, the heat-sensitive element has a structure that shields infrared rays with a housing, but the shielding part absorbs infrared rays only by shielding the infrared rays, and the temperature of the shielding part changes. There was an inconvenience of being incomplete as a reference.

  Therefore, as shown in Patent Document 3, the insulating film, the first thermal element and the second thermal element provided on one surface of the insulating film and separated from each other, and one of the insulating films A plurality of pairs of conductive wiring films formed on the surface and separately connected to the first thermal element and the second thermal element, and provided on the other surface of the insulating film facing the first thermal element. An infrared sensor has been developed that includes an infrared absorbing film and an infrared reflecting film provided on the other surface of the insulating film so as to face the second thermosensitive element.

  In this infrared sensor, the first thermal element and the second thermal element are formed on a thin insulating film with low thermal conductivity by partial infrared absorption by the infrared absorption film and partial infrared reflection by the infrared reflection film. A good temperature difference can be obtained. That is, even with a low thermal conductive insulating film that does not contain an infrared absorbing material or the like in the film, the infrared absorbing film can conduct heat due to infrared absorption only to the portion directly above the first thermal element of the insulating film. . In particular, since the heat of the infrared absorption film is conducted across a thin insulating film, the sensitivity is not deteriorated and the response is high. In addition, since the area of the infrared absorption film can be arbitrarily set, the viewing angle of infrared detection matched to the distance to the measurement object can be set by area, and high light receiving efficiency can be obtained. Moreover, the infrared ray can be reflected by the infrared reflection film to prevent the absorption of the infrared ray at the portion directly above the second heat sensitive element of the insulating film. In addition, since the infrared absorption film and the infrared reflection film are formed on the insulating film, the medium that conducts heat between the infrared absorption film and the infrared reflection film is between these films other than air. It becomes only an insulating film and the cross-sectional area to conduct becomes small. Accordingly, it is difficult for heat to be transmitted to the mutual heat sensitive elements, interference is reduced, and detection sensitivity is improved. As described above, the first heat sensitive element and the second heat sensitive element in which the influence of heat is suppressed on the insulating film having low thermal conductivity are respectively insulated from directly below the infrared absorbing film and directly below the infrared reflecting film. It has a structure for measuring the partial temperature of the adhesive film. Therefore, it is possible to obtain a good temperature difference between the first thermosensitive element used for infrared detection and the second thermosensitive element used for temperature compensation, thereby achieving high sensitivity.

JP 2002-156284 A (paragraph number 0026, FIG. 2) JP-A-7-260579 (Claims, FIG. 2) Japanese Patent Laying-Open No. 2011-13213 (Claims, FIG. 1)

The following problems remain in the conventional technology.
That is, in the infrared sensor of Patent Document 3, a good temperature difference between the first thermal element and the second thermal element can be obtained and high sensitivity can be achieved. In other words, it is susceptible to interference from surroundings and is susceptible to the influence of heat from surrounding devices. Therefore, there has been a demand for an infrared sensor that can suppress these effects and detect the temperature of the measurement object with higher sensitivity and higher accuracy.

  The present invention has been made in view of the above-mentioned problems, and makes it difficult to receive interference of radiant heat from other than the measurement object and to be hardly affected by heat from the peripheral device, thereby improving detection accuracy. An object of the present invention is to provide an infrared sensor that can be used and a circuit board including the same.

  The present invention employs the following configuration in order to solve the above problems. That is, the infrared sensor of the first invention includes an insulating film, a first thermal element and a second thermal element provided on one surface of the insulating film so as to be separated from each other, and the insulating film. A conductive first wiring film formed on one surface and connected to the first thermosensitive element, a conductive second wiring film connected to the second thermosensitive element, and the second thermosensitive element An infrared reflecting film provided on the other surface of the insulating film so as to face the element, and the insulating film is provided with the first thermal element around the first thermal element and the second thermal element. A long hole portion extending so as to avoid the wiring film and the second wiring film is formed.

  In this infrared sensor, since the insulating film is formed with a long hole portion extending around the first and second thermal elements so as to avoid the first and second wiring films. The conduction of heat from the infrared absorption region on the first thermosensitive element to the surroundings is blocked by the long hole portion, and the radiant heat from the measurement object can be thermally isolated and stored efficiently. Further, in order to prevent the temperature distribution from being disturbed by the radiant heat from the measurement object, the influence can be suppressed by blocking the heat conduction from the portion affected by the heat from the peripheral device at the long hole portion.

Moreover, the infrared sensor of 2nd invention is 1st invention. WHEREIN: Between said 1st thermal element and said 2nd thermal element, said 1st thermal element and said 2nd in said insulating film. An intermediate long hole extending in the direction of partitioning the thermal element is formed.
That is, in this infrared sensor, the insulating film has an intermediate length extending in a direction in which the first thermal element and the second thermal element are partitioned between the first thermal element and the second thermal element. Since the hole is formed, heat conduction by the insulating film between the infrared absorption region where the first thermosensitive element is mounted and the infrared reflection region where the second thermosensitive element is mounted is performed in the middle long hole portion. An even greater temperature difference can be obtained by blocking and isolating from each other.

The infrared sensor of the third invention is the infrared sensor of the first or second invention, wherein the first wiring film is arranged to the periphery of the first thermal element and is larger than the second wiring film. It is formed by an area.
That is, in this infrared sensor, since the first wiring film is arranged up to the periphery of the first thermosensitive element and has a larger area than the second wiring film, the infrared ray of the insulating film is absorbed. While improving the heat collection from the part, the heat capacity is close to the part of the insulating film where the infrared reflective film is formed, so that the fluctuation error can be reduced. The area and shape of the first wiring film are preferably set so that the heat capacity is substantially equal to the portion of the insulating film where the infrared reflective film is formed.

According to a fourth aspect of the present invention, there is provided a circuit board comprising: the infrared sensor according to any one of the first to third aspects; and a circuit unit formed on the insulating film.
That is, since this circuit board includes the infrared sensor of the present invention and a circuit unit formed on the insulating film, the circuit unit such as the control circuit and the infrared sensor are integrated on the same film. As a result, the overall size and cost can be reduced. Further, since the heat generated in the circuit unit is blocked by the long hole portion from being transmitted to the first and second thermal elements, the influence of the heat generated in the circuit unit on the temperature detection can also be suppressed. it can.

The present invention has the following effects.
That is, according to the infrared sensor and the circuit board including the infrared sensor according to the present invention, the first wiring film and the second wiring film are formed around the first thermal element and the second thermal element on the insulating film. Since the long hole portion that is avoided is formed, the radiant heat from the measurement object can be thermally isolated and stored efficiently by the long hole portion, and the influence of heat from the peripheral device can be suppressed. it can. Thereby, further higher sensitivity and higher accuracy can be achieved.

It is the top view and bottom view which show 1st Embodiment of the infrared sensor which concerns on this invention. In 1st Embodiment, it is an enlarged front view of the principal part which shows the part (a) to which the 1st thermosensitive element was adhere | attached, and the part (b) to which the 2nd thermosensitive element was adhere | attached. It is the top view and bottom view which show the circuit board of 2nd Embodiment which concerns on this invention.

  Hereinafter, a first embodiment of an infrared sensor according to the present invention will be described with reference to FIGS. 1 and 2. In each drawing used for the following description, the scale is appropriately changed in order to make each member recognizable or easily recognizable.

  As shown in FIGS. 1 and 2, the infrared sensor 1 of the present embodiment includes an insulating film 2 and a first thermosensitive element provided on one surface (lower surface) of the insulating film 2 so as to be separated from each other. 3A and the second thermal element 3B, and a pair of first wiring film 4A and second thermal element which are conductive metal films formed on one surface of the insulating film 2 and connected to the first thermal element 3A. A pair of second wiring films 4B, which are conductive metal films connected to the element 3B, and an infrared reflecting film 6 provided on the other surface of the insulating film 2 so as to face the second thermal element 3B. I have.

The pair of first wiring films 4 </ b> A has a pair of first adhesive electrodes 5 </ b> A formed on the insulating film 2 at one end thereof, and each on the insulating film 2 at the other end. A pair of formed first terminal electrodes 7A are connected.
The pair of second wiring films 4B is formed in a linear shape, and has a pair of second adhesive electrodes 5B formed on the insulating film 2 at one end thereof, and others. A pair of second terminal electrodes 7B formed on the insulating film 2 are connected to the end portions.

  The pair of first adhesive electrodes 5A are arranged up to the periphery of the first thermosensitive element 3A and are formed with a larger area than the second adhesive electrode 5B. These first adhesive electrodes 5 </ b> A are provided with the first thermosensitive element 3 </ b> A at the center of a pair and are set to have the same area as the infrared reflective film 6. That is, the first adhesive electrode 5A is set so that the heat capacity is substantially equal to the portion of the insulating film 2 where the infrared reflective film 6 is formed.

Note that the terminal electrodes 3a of the first heat sensitive element 3A and the second heat sensitive element 3B are bonded to the first adhesive electrode 5A and the second adhesive electrode 5B, respectively, with a conductive adhesive such as solder.
Further, the first terminal electrode 7A and the second terminal electrode 7B are electrodes for connection with an external circuit.

  The insulating film 2 is formed of a polyimide resin sheet, and the infrared reflection film 6, the first wiring film 4A, and the second wiring film 4B are formed of copper foil. That is, these are both surfaces in which the float electrode of copper foil used as the infrared reflecting film 6, the first wiring film 4A and the second wiring film 4B is patterned on both surfaces of the polyimide substrate used as the insulating film 2. It is made of a flexible substrate.

  The insulating film 2 has a pair of long hole portions 2a extending around the first thermal element 3A and the second thermal element 3B so as to avoid the first wiring film 4A and the second wiring film 4B. Is formed. These long hole portions 2a are grooves that are U-shaped so as to face each other, and the first thermal element 3A and the second thermal element 3B are mounted in a region between the first hole and the first thermal element 3B. The wiring film 4A, the second wiring film 4B, and the infrared reflection film 6 are formed as a central mounting region. A space between the ends of the pair of long hole portions 2a facing each other is a wiring region through which the first wiring film 4A and the second wiring film 4B pass, and also serves as a support portion for the central mounting region.

  Further, the insulating film 2 has an intermediate long hole extending in the direction of partitioning the first thermal element 3A and the second thermal element 3B between the first thermal element 3A and the second thermal element 3B. Part 2b is formed. That is, the first thermal element 3A and the second thermal element are between the first thermal element 3A and the second thermal element 3B and between the first adhesive electrode 5A and the second adhesive electrode 5B. A straight intermediate long hole portion 2b extending in a direction orthogonal to the line connecting the element 3B is formed between the pair of U-shaped long hole portions 2a.

  Further, as shown in FIG. 1A, the infrared reflection film 6 is arranged in a square shape directly on the second heat sensitive element 3B, and a copper foil and a gold plating laminated on the copper foil. It consists of a membrane. In this case, the gold plating film can function as an antioxidant film for the copper foil and improve the reflectance of infrared rays. A polyimide resin cover is provided on the lower surface of the insulating film 2 to cover the entire lower surface including the first wiring film 4A and the second wiring film 4B except for the first terminal electrode 7A and the second terminal electrode 7B. A ray (not shown) is formed.

  The infrared reflecting film 6 is formed of a material having an infrared emissivity higher than that of the insulating film 2 and is formed by applying a gold plating film on the copper foil as described above. In addition to the gold plating film, for example, a mirror-deposited aluminum vapor deposition film or an aluminum foil may be used. The infrared reflecting film 6 is formed to cover the second thermal element 3B with a size larger than that of the second thermal element 3B.

  The first thermal element 3A and the second thermal element 3B are chip thermistors in which terminal electrodes 3a are formed at both ends as shown in FIG. As this thermistor, there are thermistors of NTC type, PTC type, CTR type and the like. In this embodiment, for example, NTC type thermistors are employed as the first thermal element 3A and the second thermal element 3B. This thermistor is formed of a thermistor material such as a Mn—Co—Cu-based material or a Mn—Co—Fe-based material. The first thermal element 3A and the second thermal element 3B are mounted on the insulating film 2 by bonding the terminal electrodes 3a onto the corresponding first adhesive electrode 5A or the second adhesive electrode 5B. Has been.

  In particular, in the present embodiment, the first thermal element 3A and the second thermal element 3B are formed of a ceramic sintered body containing a metal oxide of Mn, Co, and Fe, that is, an Mn—Co—Fe-based material. Thermistor element is used. Furthermore, this ceramic sintered body preferably has a crystal structure having a cubic spinel phase as a main phase. In particular, as a ceramic sintered body, a single-phase crystal structure composed of a cubic spinel phase is most desirable. The reason why a crystal structure having a cubic spinel phase as a main phase is employed in the ceramic sintered body is that there is no anisotropy and no impurity layer, and therefore there is little variation in electrical characteristics in the ceramic sintered body. This is because high-precision measurement is possible with the thermal element 3A and the second thermal element 3B. In addition, since it has a stable crystal structure, it is highly reliable against the environment.

  As described above, in the infrared sensor 1 according to the present embodiment, the insulating film 2 is avoided by avoiding the first wiring film 4A and the second wiring film 4B around the first thermal element 3A and the second thermal element 3B. Since the elongated hole portion 2a is formed, heat conduction from the infrared absorption region on the first heat sensitive element 3A to the surroundings is blocked by the elongated hole portion 2a, and the radiant heat from the measurement object is thermally isolated. Can be stored efficiently. Further, in order to prevent the temperature distribution from being disturbed by the radiant heat from the measurement object, the heat conduction from the portion affected by the heat from the peripheral device can be blocked by the long hole portion 2a to suppress the influence.

  Further, the insulating film 2 has an intermediate length extending in a direction in which the first thermal element 3A and the second thermal element 3B are partitioned between the first thermal element 3A and the second thermal element 3B. Since the hole 2b is formed, heat conduction by the insulating film 2 is intermediate between the infrared absorption region where the first thermal element 3A is mounted and the infrared reflection region where the second thermal element 3B is mounted. A larger temperature difference can be obtained by blocking the long holes 2b and isolating them from each other.

  Further, since the first wiring film 4A is disposed to the periphery of the first thermal element 3A and has a larger area than the second wiring film 4B, the portion of the insulating film 2 that absorbs infrared rays As well as improving heat collection from the heat capacity, the heat capacity approaches the portion of the insulating film 2 where the infrared reflective film 6 is formed, so that the variation error can be reduced.

  Next, an infrared sensor according to the present invention and a second embodiment of a circuit board including the infrared sensor will be described below with reference to FIG. Note that, in the following description of the embodiment, the same components described in the above embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  The difference between the second embodiment and the first embodiment is that in the first embodiment, only the infrared sensor 1 in which the first thermal element 3A and the second thermal element 3B are mounted on the insulating film 2 is provided. On the other hand, in the second embodiment, as shown in FIG. 3, not only the infrared sensor 1 but also a circuit unit which is a sensor control detection circuit connected to the infrared sensor 1 on the insulating film 2. Reference numeral 22 also denotes a circuit board 21 provided integrally.

  That is, the circuit board 21 of the second embodiment includes the infrared sensor 1 and a circuit portion 22 formed on the insulating film 2 and connected to the first wiring film 4A and the second wiring film 4B. Yes. The circuit unit 22 is a temperature detection circuit configured by, for example, an operational amplifier. In the second embodiment, the first terminal electrode 7 </ b> A and the second terminal electrode 7 </ b> B are disposed at the same end of the insulating film 2.

  Therefore, the circuit board 21 of the second embodiment includes the infrared sensor 1 and the circuit portion 22 formed on the insulating film 2 and connected to the first wiring film 4A and the second wiring film 4B. Therefore, since the infrared sensor 1 and the circuit unit 22 such as the detection circuit are integrated on the same film, the overall size and cost can be reduced.

In addition, since the long hole 2a blocks the heat generated by the operational amplifier or the like of the circuit unit 22 from being transmitted to the first thermal element 3A and the second thermal element 3B, the temperature of the heat generated in the circuit unit 22 is detected. The influence of can also be suppressed.
The circuit portion 22 formed on the insulating film 2 together with the infrared sensor 1 may be a circuit other than the detection circuit of the infrared sensor 1, and the circuit board 21 is not limited to the infrared sensor dedicated board. A board shared with the circuit board may be used.

  The technical scope of the present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention.

  For example, in each of the above embodiments, the first heat sensitive element detects heat conducted from the insulating film that directly absorbs infrared rays, but the infrared ray is directly on the insulating film and directly above the first heat sensitive element. An absorption film may be formed. In this case, the infrared absorption effect in the first thermal element is further improved, and a better temperature difference between the first thermal element and the second thermal element can be obtained. That is, the infrared absorption film absorbs infrared rays due to radiation from the object to be measured, and the temperature of the first thermosensitive element immediately below is obtained by heat conduction through the insulating film from the infrared absorption film that absorbs infrared rays and generates heat. May be changed.

This infrared absorption film is formed of a material having an infrared absorption rate higher than that of the insulating film. For example, a film containing an infrared absorption material such as carbon black or an infrared absorption glass film (Hockey acid containing 71% silicon dioxide) A material formed of a glass film or the like can be used. In particular, the infrared absorbing film is preferably an antimony-doped tin oxide (ATO) film. This ATO film has better infrared absorption and light resistance than carbon black or the like. In addition, since the ATO film is cured with ultraviolet rays, it has a high adhesive strength and is less likely to be peeled off than carbon black or the like.
In addition, it is preferable to form this infrared rays absorption film so that this may be covered with a larger size than a 1st thermal element.

Moreover, although the 1st thermal element and the 2nd thermal element of a chip | tip thermistor are employ | adopted, you may employ | adopt the 1st thermal element and the 2nd thermal element which were formed with the thin film thermistor.
As the thermal element, a thin film thermistor or a chip thermistor is used as described above, but a pyroelectric element or the like can be used in addition to the thermistor.

  In addition, a housing fixed to one surface of the insulating film and supporting the insulating film is provided, and the first heat sensitive element and the second heat sensitive element are individually housed in the housing, and are insulated. You may provide the 1st accommodating part and the 2nd accommodating part which are covered with the air or foaming resin whose heat conductivity is lower than a film.

  DESCRIPTION OF SYMBOLS 1 ... Infrared sensor, 2 ... Insulating film, 2a ... Long hole part, 2b ... Intermediate | middle long hole part, 3A ... 1st thermal element, 3B ... 2nd thermal element, 4A ... 1st wiring film, 4B ... 2nd wiring film, 6 ... Infrared reflective film, 21 ... Circuit board, 22 ... Circuit part

Claims (4)

An insulating film;
A first thermal element and a second thermal element provided on one surface of the insulating film so as to be spaced apart from each other;
The insulating one is formed on a surface of the first pair of connected conductive thermosensitive element first wiring layer and the pair of second connected conductive to the second heat sensitive element of the film A wiring film;
An infrared reflection film provided on the other surface of the insulating film facing the second thermosensitive element;
The insulating film has a pair of long hole portions extending in a line around the first thermal element and the second thermal element while avoiding the first wiring film and the second wiring film. Formed ,
In the region between the pair of long hole portions, the first thermal element and the second thermal element are mounted, and the first wiring film, the second wiring film, and the infrared reflective film are The central mounting area,
The pair of long hole portions are formed in a U-shape opposed to each other, and between the ends of the pair of long hole portions, a portion of the pair of first wiring films adjacent to each other and a pair of the second holes An infrared sensor characterized in that the wiring film is a wiring region through which a portion of the wiring film close to each other passes and is a support portion of the central mounting region . The infrared sensor according to claim 1,
An intermediate long hole extending in the insulating film between the first heat sensitive element and the second heat sensitive element in a direction separating the first heat sensitive element and the second heat sensitive element. An infrared sensor characterized in that is formed. The infrared sensor according to claim 1 or 2,
An infrared sensor characterized in that the first wiring film is disposed even around the first thermal element and has a larger area than the second wiring film. The infrared sensor according to any one of claims 1 to 3,
A circuit board comprising a circuit portion formed on the insulating film.

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