JP5287906B2 - Infrared temperature sensor, electronic device, and method of manufacturing infrared temperature sensor - Google Patents

Description

  The present invention relates to an infrared temperature sensor that detects the temperature of an object using infrared rays generated by the object.

  In recent electronic devices, the surrounding environment is detected and the detection result is used for operation control. For example, in an air conditioner, operation control is performed in which the presence of a person is detected and temperature control is performed targeting a place where the person exists. In such operation control, a sensor device for detecting the surrounding environment is used, and in the air conditioner as described above, an infrared temperature sensor that detects an object temperature in a non-contact manner by radiant heat from the object is used.

  As a conventional infrared temperature sensor, a configuration in which a sensor element and a circuit unit are mounted on a metal stem is well known (for example, Patent Document 1). The configuration of an infrared temperature sensor using a metal stem is shown in FIG.

  The infrared temperature sensor shown in FIG. 7 includes a sensor element 102 and a circuit unit (not shown) for amplifying and outputting a detection signal of the sensor element 102 on a metal stem 101. Further, the metal stem 101 is provided with an electrode rod 103 penetrating therethrough, and the circuit portion and the mounting substrate are connected via the electrode rod 103. Further, the mounting surface of the sensor element 102 and the circuit unit in the metal stem 101 is covered with a metal cap 104. The metal cap 104 is provided with a window for transmitting infrared rays, and a filter 105 made of glass or transparent resin having high infrared transmittance is attached to the window.

  In the infrared temperature sensor, the greatest reason for using the metal stem 101 is to counter errors due to internal heat. That is, the sensor element 102 receives not only infrared rays that pass through the filter 105 but also infrared rays due to radiant heat inside the sensor. At this time, if the temperature inside the sensor is the same as that of the sensor element 102, the influence of the temperature inside the sensor is canceled and no error occurs. On the other hand, if the temperature inside the sensor is different from the sensor element 102, the temperature inside the sensor will be an error, and the temperature of the measurement object cannot be detected accurately.

  For this reason, the conventional infrared temperature sensor has a package structure using a metal stem and a metal cap having high thermal conductivity so that the temperature inside the sensor is uniform.

  An infrared temperature sensor having a structure that does not use a metal stem is disclosed in Patent Document 2, for example. FIG. 8 shows the configuration of an infrared temperature sensor that does not use a metal stem.

  The infrared temperature sensor shown in FIG. 8 has a configuration in which a sensor chip 202 is directly mounted on a support substrate 201 and the wiring of the support substrate 201 and the sensor chip 202 are connected by wire. Also in the infrared temperature sensor, the sensor chip 202 is covered with a metal cap 203.

JP-A-6-137935 (published on May 20, 1994) Special Table 2007-503586 (published February 22, 2007)

  However, the prior art as described above has the following problems.

  First, in the structure using a metal stem, the member cost of the metal stem itself is high. The metal stem has an electrode bar for taking out a sensor signal to the outside of the package, and this electrode bar is insulated from the main body of the stem using low-melting glass or the like, so that the structure is complicated and the member cost is high. . In addition, the mounting of the metal stem requires a process of inserting the metal rod of the through hole of the mounting board and soldering it manually, which increases the assembly processing cost.

  On the other hand, in a structure that does not use a metal stem, when the base material of the support substrate is a general resin base material, a thermal difference is likely to occur between the sensor chip and the cap because the thermal conductivity is poor. For this reason, when ambient temperature changes etc., the problem that a sensor output fluctuates by the radiant infrared rays inside a package arises.

  Moreover, in the structure which does not use a metal stem, the said problem can be eliminated by making the base material of a support substrate into a ceramic base material with good heat conductivity. However, in this case, the price of the ceramic substrate becomes very high, which is disadvantageous in terms of cost.

  The present invention has been made in view of the above-mentioned problems, and is low in material cost and assembly processing cost, and is resistant to fluctuations in output to environmental temperature changes comparable to the conventional structure using a metal stem. It aims at providing the infrared temperature sensor which has this.

  In order to solve the above problems, an infrared temperature sensor of the present invention includes a mounting substrate, a metal plate mounted on the mounting substrate, a sensor chip that receives and detects infrared rays mounted on the metal plate, A circuit unit that amplifies a detection signal of the sensor chip mounted on the metal plate; and a metal cap that is placed on the metal plate and covers the sensor chip and the circuit unit. Is provided with an opening, and the electrode on the mounting substrate and the circuit portion are wire-connected through the opening.

  According to said structure, the said sensor chip and the said circuit part are mounted on the said metal plate, and also a metal cap is covered from it. That is, the sensor has a structure in which the sensor chip and the circuit unit are accommodated in a package including the metal plate and the metal cap. Since the metal plate and the metal cap have high thermal conductivity, the package has a function of keeping the temperature inside the sensor uniform, and can have high output fluctuation resistance against environmental temperature changes.

  The metal plate is provided with an opening, and the electrode on the mounting substrate and the circuit part are wire-connected through the opening. For such wire bonding between the mounting substrate and the circuit portion, a normal COB (Chip On Board) mounting technology can be applied. Therefore, the assembly processing cost is significantly higher than the conventional technology for mounting a sensor using a metal stem. Reduction is possible.

  In the infrared temperature sensor, the metal plate may be connected to a GND potential on the mounting substrate, and the metal cap may be electrically connected to the metal plate.

  According to said structure, the shield effect which interrupts | emits radio noise can be given to the package which consists of the said metal plate and the said metal cap.

  In the infrared temperature sensor, the metal plate is mounted on the mounting substrate by soldering, and the soldering lands formed on the mounting substrate have four corners of the metal plate to be mounted or It can be set as the structure provided in the location corresponding to 4 sides, and the location corresponding to the center of a metal plate.

  According to said structure, a metal plate can be firmly mounted without position shift with the soldering land provided in the location corresponding to four corners or four sides of the said metal plate. A land provided at a location corresponding to the center of the metal plate can prevent the metal plate from being bent due to a gap between the metal plate and the mounting substrate.

  In the infrared temperature sensor, the metal plate may be provided with a surface coating for ensuring solderability. Thereby, the reliability of solder mounting can be raised.

  In the infrared temperature sensor, the metal plate may be provided with a cap positioning protrusion for positioning the metal cap. Thereby, when mounting the said metal cap on the said metal plate, it can position easily with sufficient precision.

  In the infrared temperature sensor, a resin inner cap may be provided inside the metal cap.

  According to the above configuration, it is possible to avoid a rapid change in the temperature inside the sensor following the change in the external environment temperature, and it is possible to improve the output fluctuation resistance to the change in the ambient temperature of the sensor.

  In the infrared temperature sensor, a window for taking infrared light into the sensor is provided on the upper surface of the metal cap, and infrared light passing through the window is directly below the window on the sensor chip. A lens for condensing light is disposed on the inner cap, and the inner cap has a recess for fitting the lens.

  According to said structure, the hollow part for fitting the said lens is provided in the said inner cap, The position alignment for adjusting the focus of a lens on a sensor chip becomes easy.

  In the infrared temperature sensor, the periphery of the lens is disposed in contact with or close to the metal cap, and the gap between the lens and the metal cap is filled with an adhesive. it can. Thereby, the thermal conductivity between the metal cap and the lens can be improved, and the temperature in the sensor can be made uniform.

  The method for manufacturing an infrared temperature sensor of the present invention includes a step of mounting a metal plate provided with an opening on a mounting substrate, a sensor chip for receiving and detecting infrared light on the metal plate, and the sensor chip. Mounting a circuit unit for amplifying the detection signal of the sensor, a step of wire-connecting the electrode on the mounting substrate and the circuit unit through an opening of the metal plate, and the sensor chip on the metal plate And packaging with a metal cap covering the circuit portion.

  According to the above configuration, it is possible to manufacture an infrared temperature sensor that is low in member cost and assembly processing cost, and has an output fluctuation resistance to an environmental temperature change comparable to that of a conventional structure using a metal stem.

  The infrared temperature sensor of the present invention has a structure in which the sensor chip and the circuit unit are accommodated in a package including the metal plate and the metal cap. Since the package has high thermal conductivity, it has a function of keeping the temperature inside the sensor uniform. For this reason, the infrared temperature sensor has an effect of having high output fluctuation resistance against environmental temperature changes.

  The metal plate is provided with an opening, and the electrode on the mounting substrate and the circuit part are wire-connected through the opening. For such wire bonding between the mounting substrate and the circuit unit, a normal COB mounting technique can be applied. For this reason, the infrared temperature sensor has an effect that the cost of assembling can be significantly reduced as compared with the conventional technique in which a sensor using a metal stem is mounted.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view illustrating a configuration of an infrared temperature sensor according to an embodiment of the present invention. It is a perspective view which shows the shape of the metal plate used with the infrared temperature sensor of FIG. It is a perspective view which shows the mounting method of the metal plate in the infrared temperature sensor of FIG. It is sectional drawing which shows the sealing structure of the metal cap and lens in the infrared temperature sensor of FIG. It is a perspective view which shows the mounting method of the metal cap in the infrared temperature sensor of FIG. It is a graph which shows the output fluctuation tolerance to the environmental temperature change in an infrared temperature sensor. It is sectional drawing which shows the structure of the conventional infrared temperature sensor. It is sectional drawing which shows the structure of the conventional infrared temperature sensor.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view showing a configuration of an infrared temperature sensor according to the present embodiment. In FIG. 1, a part of the infrared temperature sensor is shown in cross section so that the internal structure of the infrared temperature sensor can be seen. The infrared temperature sensor according to the present embodiment can be used in an electronic device (such as an air conditioner) that detects the surrounding environment and uses the detection result for operation control.

  The infrared temperature sensor shown in FIG. 1 includes a laminated substrate 1, a metal plate 2, a sensor chip 3, an ASIC (Application Specific Integrated Circuit) 4, a metal cap 5, an inner cap 6, and a lens 7. The multilayer substrate 1 is a mounting substrate for mounting the sensor chip 3 and the ASIC 4, and has a wiring layer patterned in a predetermined shape. The sensor chip 3 is an element that receives and detects infrared rays, and the ASIC 4 is a circuit unit that amplifies and outputs the detection signal of the sensor chip 3.

  A metal plate 2 is attached on the laminated substrate 1, and the sensor chip 3 and the ASIC 4 are mounted on the metal plate 2. The metal plate 2 is provided with an opening 21 for wire connection between the laminated substrate 1 and the ASIC 4. The shape of the metal plate 2 in the present embodiment is shown in FIG.

  A structure composed of a metal cap 5, an inner cap 6 and a lens 7 is placed on the sensor chip 3 and the ASIC 4. The lens 7 is fitted into a recess formed on the upper surface of the inner cap 6, and the metal cap 5 is placed thereon. The metal cap 5 completely accommodates the inner cap 6 and the lens 7 inside thereof, and the lower end thereof is in contact with the metal plate 2. In addition, a window portion for taking in infrared rays into the sensor is provided on the upper surface of the metal cap 5, and the lens 7 is disposed immediately below the window portion.

  The lens 7 collects infrared rays that pass through the window portion of the metal cap 5 on the sensor chip 3. As a result, the infrared temperature sensor can efficiently detect infrared rays.

  The gap between the metal plate 2 and the metal cap 5 and the gap between the lens 7 and the metal cap 5 are sealed with an adhesive so that the inside of the sensor is sealed. Of course, this is because if the inside of the sensor is not sealed, it is difficult to maintain the temperature inside the sensor due to the entry and exit of air. However, the infrared transmitting member attached to the window portion of the metal cap 5 does not necessarily need to be a lens, and may be a glass plate, a transparent resin plate, or the like if the light condensing function is not required.

  In the infrared temperature sensor having the above configuration, a package structure including the metal plate 2 and the metal cap 5 is formed, and the sensor chip 3 and the ASIC 4 are disposed inside the package. For this reason, it becomes possible to keep the temperature in the sensor uniform to the same extent as a sensor having a conventional structure using a metal stem. That is, it is possible to provide an infrared temperature sensor having an output fluctuation resistance to an environmental temperature change comparable to the conventional structure.

  Although the material of the metal plate 2 is not specifically limited, Iron, copper, aluminum, etc. with especially favorable heat conductivity can be used suitably. Further, the metal plate 2 may be subjected to surface coating (for example, nickel plating) in order to prevent rust and ensure solderability described later.

  The inner cap 6 is made of resin. The main purpose of providing the inner cap 6 is to avoid a sudden change in the temperature in the sensor following the change in the external temperature. As described above, since the detection error occurs when the temperature inside the sensor is not uniform, the infrared temperature sensor keeps the temperature inside the sensor uniform by the package structure of the metal plate 2 and the metal cap 5. . However, if only the thermal conductivity in the package is improved, when the external temperature changes rapidly, the temperature in the sensor also changes abruptly. Regarding the temperature in the sensor, it is not preferable that such a rapid temperature occurs. For this reason, in the infrared temperature sensor, an inner cap 6 made of resin is provided to mitigate the change in the external temperature and avoid a sudden change in the sensor internal temperature.

  Then, the assembly procedure of the said infrared temperature sensor is demonstrated. First, the metal plate 2 is mounted on the multilayer substrate 1 by soldering. In this soldering process, it is possible to use a general soldering method in the mounting technology of electronic components, such as placing the metal plate 2 on the multilayer substrate 1 with cream solder interposed therebetween and heating by reflow. It is.

  Thus, in order to mount the metal plate 2 on the multilayer substrate 1 by soldering, soldering lands are formed in advance on the multilayer substrate 1 (see FIG. 3). The soldering lands are provided in correspondence with at least four positions that extend from the center of the metal plate 2 to the edge of the metal plate 2 at equal positions vertically and horizontally. The soldering lands may be provided at locations corresponding to the four corners or four sides of the metal plate 2 to be mounted. Moreover, it is preferable to form a soldering land at a location corresponding to the substantially center of the metal plate 2. This is to prevent the metal plate 2 from being bent due to a gap between the metal plate 2 and the laminated substrate 1 near the center of the metal plate 2. A land corresponding to the center of the metal plate 2 may be one place or a plurality of places.

  Subsequently, the sensor chip 3 and the ASIC 4 are mounted on the metal plate 2. The sensor chip 3 and the ASIC 4 can be mounted on the metal plate 2 with an adhesive. Thereafter, wiring connection (connection between the sensor chip 3 and the ASIC 4 and connection between the ASIC 4 and the multilayer substrate 1) is performed by wire bonding. As described above, the metal plate 2 is provided with the opening 21 for wire connection between the multilayer substrate 1 and the ASIC 4. That is, in the state where the metal plate 2 is mounted on the multilayer substrate 1, the connection pads (electrodes) on the multilayer substrate 1 side are arranged in the region of the opening 21. Therefore, wire bonding between the laminated substrate 1 and the ASIC 4 can be performed through the opening 21. The wire bonding between the multilayer substrate 1 and the ASIC 4 can be performed by using an ordinary COB (Chip On Board) mounting technique. Therefore, the assembly cost can be greatly reduced as compared with the conventional technique for mounting a sensor using a metal stem. Is possible.

  The metal cap 5, the inner cap 6, and the lens 7 are assembled before mounting on the laminated substrate 1. First, the lens 7 is fitted into a recess formed on the upper surface of the inner cap 6, and the metal cap 5 is placed thereon. The lens 7 needs to be accurately aligned so that its focal point comes on the sensor chip, but this positioning is facilitated by providing the inner cap 6 with a recess for fitting the lens 7.

  The peripheral portion of the lens 7 is disposed in contact with or close to the metal cap 5, and the gap between the metal cap 5 and the lens 7 is sealed with an adhesive. At this time, the adhesive preferably fills substantially the entire gap between the metal cap 5 and the lens 7 (see FIG. 4). This not only enhances the sealing performance, but also improves the thermal conductivity between the metal cap 5 and the lens 7.

  The assembly of the metal cap 5, the inner cap 6 and the lens 7 is placed on the metal plate 2 of the laminated substrate 1 where the mounting of the sensor chip 3 and the ASIC 4 is completed, and the sensor is packaged. At this time, the metal cap 5 and the metal plate 2 are sealed with an adhesive, and the inside of the infrared temperature sensor is sealed. In order to facilitate mounting of the assembly, the metal plate 2 may be provided with cap positioning protrusions 22 (see FIG. 5). The cap positioning protrusions 22 are preferably provided at four corners or four sides of the metal plate 2. Thereby, when mounting the metal cap 5 on the metal plate 2, it can be positioned easily and accurately.

  FIG. 6 shows output fluctuation tolerance to environmental temperature changes in the infrared temperature sensor according to the present embodiment. FIG. 6 is a graph showing the fluctuation of the output temperature when the ambient temperature of the sensor is raised from 25 ° C. to 35 ° C. (the time required for the temperature fluctuation is about 100 s), with the horizontal axis representing time and the vertical axis representing sensor. Output temperature error is shown. FIG. 6 shows the measurement results of the sensors in Comparative Examples 1 and 2 in addition to the sensor of the present embodiment. Here, Comparative Example 1 corresponds to the conventional structure of Patent Document 1, and is a structure in which a sensor chip is mounted on a mounting substrate via a metal stem. In Comparative Example 2, as in the present invention, the sensor chip is mounted on the mounting substrate via the metal plate, but the gap between the lens and the metal cap is not filled with resin. Structure.

  First, in the sensor according to the present embodiment, the error in the output temperature is within about ± 0.5 ° C. despite the sudden change in the ambient temperature, and the error that occurs after the change in the ambient temperature is also returned. fast. On the other hand, in the sensor of Comparative Example 1, the maximum error is close to 0.8 ° C., and an error of 0.5 ° C. or more occurs until a time of about 300 s elapses after the temperature change starts. As a result, the sensor according to the present embodiment has an output fluctuation resistance to environmental temperature changes equivalent to or higher than that of a conventional sensor using a metal stem, regardless of an inexpensive structure that does not use a metal stem. You can see that

  Further, in the sensor of Comparative Example 2, a maximum error close to 2.0 ° C. occurs, and it takes about 700 s until the error converges to about 0.5 ° C. From this, it can be seen that even if the heat dissipation is increased through a metal plate between the mounting substrate and the sensor chip, the sensor does not have the output fluctuation resistance if there is no airtightness in the sensor.

  In the infrared temperature sensor of the present invention, the metal plate 2 is connected to the GND potential on the laminated substrate 1, and the metal plate 2 and the metal cap 5 are electrically connected by a conductive adhesive. Is preferred. The sensor chip 3 and the ASIC 4 are sensitive devices that are easily affected by radio wave noise. However, with the above-described configuration, the package including the metal plate 2 and the metal cap 5 can have a shielding effect for blocking radio wave noise. . Further, the above configuration can be easily realized by connecting at least one of the soldering lands on the multilayer substrate 1 to the GND potential supply wiring.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

  The present invention can be used for an electronic device (such as an air conditioner) that detects the surrounding environment and uses the detection result for operation control.

1 Laminated board (mounting board)
2 Metal plate 3 Sensor chip 4 ASIC (circuit part)
5 Metal cap 6 Inner cap 7 Lens 21 Opening 22 Cap positioning protrusion

Claims (8)

A mounting board;
A metal plate mounted on the mounting substrate;
A sensor chip that receives and detects infrared rays mounted on the metal plate;
A circuit unit for amplifying a detection signal of the sensor chip mounted on the metal plate;
A metal cap that covers the metal plate and covers the sensor chip and the circuit unit;
The metal plate is provided with an opening, and the electrode on the mounting substrate and the circuit part are wire-connected through the opening ,
The metal plate is connected to the GND potential on the mounting substrate,
The metal cap is electrically connected to the metal plate,
The metal plate is mounted on the mounting board by soldering,
The soldering lands formed on the mounting board are provided at locations corresponding to four corners or four sides of the metal plate to be mounted and locations corresponding to the center of the metal plate. Infrared temperature sensor. 2. The infrared temperature sensor according to claim 1 , wherein the metal plate is provided with a surface coating for ensuring solderability. The aforementioned metal plate, infrared temperature sensor according to claim 1 or 2, characterized in that the cap positioning protrusion for positioning the metal cap is provided. The infrared temperature sensor according to any one of claims 1 to 3 , wherein an inner cap made of resin is provided inside the metal cap. On the upper surface of the metal cap, a window portion for taking in infrared rays into the sensor is provided, and a lens for condensing the infrared rays passing through the window portion on the sensor chip is disposed immediately below the window portion. And
The infrared temperature sensor according to claim 4 , wherein the inner cap has a depression for fitting the lens. 6. The infrared temperature according to claim 5 , wherein a peripheral portion of the lens is disposed in contact with or close to the metal cap, and a gap between the lens and the metal cap is filled with an adhesive. Sensor. An electronic apparatus comprising the infrared temperature sensor according to any one of claims 1 to 6 . An infrared temperature sensor manufacturing method for manufacturing the infrared temperature sensor according to any one of claims 1 to 6,
Mounting a metal plate provided with an opening on a mounting substrate;
On the metal plate, a step of mounting a sensor chip that receives and detects infrared rays and a circuit unit that amplifies the detection signal of the sensor chip;
Wire-connecting the electrode on the mounting substrate and the circuit portion through the opening of the metal plate;
And a step of covering the metal plate with a metal cap that covers the sensor chip and the circuit part, and packaging the infrared chip.

Images