JP2011033479A - Temperature sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a temperature sensor capable of precisely measuring temperatures of electronic components, by suppressing the influence of thermal resistance of a substrate or a radiating board, and capable of being electrically insulated from a circuit on the substrate. <P>SOLUTION: The temperature sensor includes a heat-conductive sheet 4, which is sandwiched between an electronic component 2 and a substrate 3 mounted with the electronic component 2, in a close contact state to transfer the heat of the electronic component 2 to the substrate 3 and a heat-sensitive element 5 attached to the heat conductive sheet 4. Thus, the heat conductive sheet 4 in close contact with the electronic component 2 efficiently transfers heat from the electronic component 2, such as, a transistor to the heat-sensitive element 5 without having to go via the substrate 3, so that temperatures of the electronic component 2 can exactly be measured by suppressing the influence of thermal resistance of the substrate 3. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a temperature sensor that can accurately measure the temperature of an electronic component such as a transistor.

  Conventionally, when measuring the temperature of a heat-generating electronic component such as a transistor, for example, by attaching a temperature sensor such as a chip thermistor to a substrate on which the electronic component is mounted or a heat sink attached to the electronic component, Measuring the temperature of electronic components. In other words, in order to protect against damage due to temperature rise in power transistors, power FETs, etc., the junction temperature is measured by an attached temperature sensor, and the temperature is limited or stopped when the temperature exceeds a predetermined temperature. Control is performed accordingly. For this reason, an approximate junction temperature has been estimated by attaching a temperature sensor to the mounting board or the heat sink near the electronic components and measuring the temperature of the board or the heat sink.

  For example, in Patent Document 1, a terminal for an electronic component such as a power transistor or a power FET that generates heat during operation and a temperature detection element such as a thermistor or a temperature detection IC for detecting a temperature change of the electronic component are attached. A printed circuit board on which lands are formed has been proposed. In this technology, the temperature detection element, which is a temperature sensor, is mounted in proximity to an electronic component mounted on a printed circuit board via a shared land, and thereby the temperature of the electronic component is controlled via a heat sink. The temperature is measured with less thermal resistance variation and better thermal conductivity than when measuring.

JP 2006-237144 A (Claims)

The following problems remain in the conventional technology.
That is, in the above-described conventional technology, a temperature sensor is mounted on a substrate on which electronic components are mounted or on a heat sink with electronic components mounted thereon, and the temperature of the substrate and the heat sink is measured with this temperature sensor. The temperature of the component is estimated, but there is a variation in the influence of the thermal resistance of the substrate and the heat sink, and it is difficult to accurately measure the junction temperature and the like. In addition, when temperature sensors are mounted on the same substrate on which electronic components are mounted, the temperature detection circuit is expensive because it electrically insulates the large current circuit and inverter circuit formed on the substrate. There is also the inconvenience of becoming. In particular, in the case of Patent Document 1, since a thermistor is directly mounted on a substrate, a temperature detection circuit is separately required on the substrate, and a common land pattern for connecting a transistor terminal and a thermistor terminal is previously formed on the substrate. There was an inconvenience that it had to be produced in a necessary place.

  The present invention has been made in view of the above-described problems, and can accurately measure the temperature of an electronic component while suppressing the influence of the thermal resistance of the substrate and the heat sink and can be electrically insulated from the circuit on the substrate. An object is to provide a temperature sensor.

  The present invention employs the following configuration in order to solve the above problems. That is, the temperature sensor of the present invention is installed between an electronic component and a substrate or a heat radiating plate on which the electronic component is mounted so as to be in close contact with them, and heat of the electronic component is transferred to the substrate or the heat radiating plate. A heat conductive sheet to be conducted and a heat sensitive element installed on the heat conductive sheet are provided.

  Since this temperature sensor includes a heat sensitive element installed on the heat conductive sheet, the heat conductive sheet in close contact with the electronic component efficiently transfers heat from the electronic component such as a transistor to the heat sensitive element without using a substrate or a heat sink. By conducting, it is possible to accurately measure the temperature of the electronic component while suppressing the influence of the thermal resistance of the substrate and the heat sink. Also, since the temperature sensor is installed not between the board and the electronic component and the board or the heat sink, the temperature detection circuit can be electrically insulated from the circuit on the board, and is inexpensive. It can be measured accurately with a temperature detection circuit. Furthermore, it is not necessary to previously form a pattern wiring such as a temperature detection circuit or a sensor land on the substrate or the heat radiating plate, and an existing member can be used as it is, so that an increase in member cost can be suppressed. Moreover, since the heat | fever of an electronic component is conducted to a board | substrate or a heat sink via a heat conductive sheet with high adhesiveness, high heat dissipation can also be obtained.

Moreover, the temperature sensor of the present invention is characterized in that the thermal element is embedded in the thermal conductive sheet.
That is, in this temperature sensor, since the thermal element is embedded in the heat conductive sheet, heat is also transmitted from the outer peripheral surface of the embedded thermal element, and heat can be more efficiently conducted.

Furthermore, the temperature sensor of the present invention is characterized in that the thermal element is installed directly below the electronic component.
That is, in this temperature sensor, since the thermal element is installed directly under the electronic component, the heat of the electronic component is directly underneath and directly transmitted to the thermal element in the proximity state, so that more accurate and high-speed temperature measurement can be performed. It becomes possible.

The present invention has the following effects.
That is, according to the temperature sensor according to the present invention, since the thermosensitive element installed on the heat conductive sheet is provided, it is possible to accurately measure the temperature of the electronic component while suppressing the influence of the thermal resistance of the substrate and the heat sink. It is possible to achieve electrical insulation from the circuit on the substrate.
Therefore, according to the temperature sensor of the present invention, the junction temperature and the like of the transistor can be accurately measured, and the operation control according to the temperature can be more accurately performed.

In 1st Embodiment of the temperature sensor which concerns on this invention, it is a top view which shows the temperature sensor of a mounting state. It is AA arrow sectional drawing of FIG. In 2nd Embodiment of the temperature sensor which concerns on this invention, it is a top view which shows the temperature sensor of the mounting state. FIG. 3 is a cross-sectional view taken along line B-B in FIG. 2.

  Hereinafter, a temperature sensor according to a first embodiment of 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 temperature sensor 1 of the present embodiment is for measuring the temperature of an electronic component 2 that generates heat during operation, for example. The electronic component 2 and the electronic component 2 are mounted on the temperature sensor 1. A heat conductive sheet 4 that is placed in close contact with the substrate 3 and conducts heat of the electronic component 2 to the substrate 3, and a heat sensitive element 5 installed on the heat conductive sheet 4. I have.

The electronic component 2 is a transistor such as a power transistor or a power FET. That is, when the electronic component 2 is a transistor, the temperature sensor 1 of the present embodiment measures the junction temperature for driving control of the transistor.
The substrate 3 is a printed circuit board on which pattern wiring (not shown) of a large current circuit or inverter circuit connected to the electronic component 2 to be mounted is formed, for example, and a lead frame terminal of the electronic component 2 is formed on the pattern wiring. 2a is adhesively fixed.

The heat conductive sheet 4 is preferably an adhesive insulating sheet. For example, a sheet such as acrylic, silicon rubber, elastomeric silicon, glass fiber, dielectric film, or polyester film can be used.
In addition to the substrate 3 on which the electronic component 2 is mounted, the heat conductive sheet 4 is sandwiched between the electronic component 2 and a heat sink (a heat sink) such as aluminum attached in contact with the electronic component 2. You may install in the state.

The thermal element 5 is a thermal resistance element such as a thermistor element, and a pair of electrodes 5a are formed on the surface. Lead electrodes 6 connected to external temperature detection circuits are soldered to the electrodes 5a.
The heat sensitive element 5 is bonded to the position close to the electronic component 2 on the heat conductive sheet 4 with an adhesive 7. The adhesive 7 preferably has the same thermal conductivity as that of the heat conductive sheet 4.

  Examples of the thermistor elements that can be employed in the thermal element 5 include a chip thermistor and a thin film thermistor. As these thermistors, there are thermistors of NTC type, PTC type, CTR type and the like. In this embodiment, for example, an NTC type thermistor is adopted as the thermal element 5. This thermistor is formed of a thermistor material such as a Mn—Co—Cu-based material or a Mn—Co—Fe-based material.

  As described above, since the temperature sensor 1 of the present embodiment includes the thermal element 5 installed on the thermal conductive sheet 4, the thermal conductive sheet 4 that has higher thermal conductivity than the substrate 3 and is in close contact with the electronic component 2, By efficiently conducting heat from the electronic component 2 such as a transistor to the thermal element 5 without going through the substrate 3, the influence of the thermal resistance of the substrate 3 can be suppressed and the temperature of the electronic component 2 can be accurately measured. .

  Moreover, since the temperature sensor 1 is installed not between the substrate 3 but between the electronic component 2 and the substrate 3, the temperature detection circuit can be electrically insulated from the circuit on the substrate 3, Accurate measurement is possible with an inexpensive temperature detection circuit. Furthermore, it is not necessary to previously form a pattern wiring such as a temperature detection circuit or a sensor land on the substrate 3, and an existing member can be used as it is, so that an increase in member cost can be suppressed. Moreover, since the heat | fever of the electronic component 2 is conducted to the board | substrate 3 through the heat conductive sheet 4 with high adhesiveness, high heat dissipation can also be obtained.

  Next, a second embodiment of the temperature sensor according to the present invention will be described below with reference to FIGS. 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, the thermal element 5 is fixed to the surface of the heat conductive sheet 4, whereas in the temperature sensor 21 of the second embodiment, As shown in FIGS. 3 and 4, the thermal element 5 is embedded in the heat conductive sheet 24. The heat sensitive element 5 is also different from the first embodiment in that the heat sensitive element 5 is installed so as to be able to be contacted directly below the electronic component 2.

That is, a rectangular hole 24a corresponding to the outer shape of the elongated heat-sensitive element 5 is formed in the center of the region where the electronic component 2 is installed on the surface side of the heat conductive sheet 24, and the hole The thermal element 5 is embedded in 24a, the surface is exposed, and the electronic component 2 can be contacted.
The lead wire 6 connected to the electrode 5 a of the thermal element 5 is drawn out from both sides of the electronic component 2. A groove or a hole may be formed in the heat conductive sheet 24 in order to draw out the lead wire 6 connected to the electrode 5a of the thermal element 5 to the outside.

Therefore, in the temperature sensor 21 of the second embodiment, since the heat sensitive element 5 is embedded in the heat conductive sheet 24, heat is transmitted from the outer peripheral surface of the embedded heat sensitive element 5, and heat conduction is performed more efficiently. be able to.
In addition, since the thermal element 5 is installed directly under the electronic component 2, the heat of the electronic component 2 is directly below and directly transmitted to the thermal element 5 in the close state, thereby enabling more accurate and high-speed temperature measurement. become. In particular, since the thermal element 5 is installed so as to be in contact with the electronic component 2, not only the heat via the heat conductive sheet 24 but also the direct heat from the electronic component 2 can be measured, and more accurate measurement is possible. It is.

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, as the thermal element, a thermistor element such as a chip thermistor is used as described above, but a pyroelectric element or the like can be used in addition to the thermistor.

  DESCRIPTION OF SYMBOLS 1,21 ... Temperature sensor, 2 ... Electronic component, 3 ... Board | substrate, 4,24 ... Thermal conductive sheet, 5 ... Thermal element, 6 ... Lead wire

Claims (3)

Heat that is placed in close contact with an electronic component and a substrate on which the electronic component is mounted or a heat sink attached to the electronic component, and conducts heat of the electronic component to the substrate or the heat sink A conductive sheet;
A temperature sensor comprising: a thermosensitive element installed on the heat conductive sheet. The temperature sensor according to claim 1,
The temperature sensor, wherein the thermosensitive element is embedded in the heat conductive sheet. The temperature sensor according to claim 2,
The temperature sensor, wherein the thermal element is installed directly below the electronic component.

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