JP2008153525A - Temperature sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress variation in detection accuracy caused by a difference in temperature environment between elements, reduce variation in response by preventing the displacement of the element, and suppress the deterioration of the detection accuracy by controlling heat dissipation caused by a lead line in temperature sensor. <P>SOLUTION: A temperature sensor includes a chip-like thermistor element 11, a chip-like resistive element 12 electrically connected with the thermistor element 11, a circuit substrate 14 on the surface wiring pattern 13 of which the thermistor element 11 and the resistive element 12 are mounted, a lead line 15 connected to the wiring pattern 13 of the circuit substrate 14, and a sealing resin portion 16 which seals the thermistor element 11 and the resistive element 12 in such a manner that the entire circuit substrate 14 is sealed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a temperature sensor having a thermistor used for various temperature detections.

  In general, in a temperature sensor using a thermistor element, as a signal processing (temperature conversion) method of the thermistor, a temperature detection circuit of a voltage output combined with a resistor is configured, a resistance change due to the temperature of the thermistor is taken out as a voltage, AD conversion, etc. A method for detecting the temperature is employed. As this temperature detection circuit, as shown in the equivalent circuit of FIG. 7, an input terminal electrode 1, a resistor 2, an output terminal electrode 3, an NTC thermistor (Negative Temperature Coefficient Thermistor) 4, and an earth terminal electrode 5 are connected in series in this order. Is known.

This temperature detection circuit converts the output voltage to temperature by applying a voltage between the input terminal electrode 1 and the ground terminal electrode 5 and measuring the voltage between the output terminal electrode 3 and the ground terminal electrode 5. Thus, a temperature change can be detected.
Conventionally, for example, Patent Document 1 proposes a thick film thermistor in which a thermistor thick film and a resistor thick film are formed on an upper surface (front surface) of an insulating substrate to constitute the temperature detection circuit.

  Although not constituting the temperature detection circuit, Patent Document 2 proposes a temperature sensor in which a single thermistor element and a resistance element connected by lead wires are sealed with resin. In this temperature sensor, a resistance element is connected to adjust the resistance of the thermistor element.

Japanese Patent Laid-Open No. 10-312916 (Claims, FIG. 7) JP-A 63-145930 (Claims, FIG. 1)

The following problems remain in the conventional technology.
That is, in a temperature sensor using a thermistor, the resistance value accuracy of the thermistor and the B constant (resistance temperature coefficient) accuracy are important from the viewpoint of temperature detection accuracy. Resistance value accuracy (temperature characteristics) and resistance value matching between the thermistor and resistance are more important. In Patent Document 1, the temperature detection circuit is configured by forming the thermistor thick film and the resistor thick film on the chip surface. Conventionally, when the temperature detection circuit is configured using a single thermistor element, In addition, a configuration is adopted in which a resistance element is provided in a circuit built in the measurement apparatus main body connected by a lead wire separately from the sensor portion having the thermistor element. However, since the single thermistor element and the resistive element are provided separately and are in different temperature environments, it is difficult to obtain a highly accurate linear temperature detection due to a difference in temperature characteristics due to the temperature difference. there were. For this reason, it is conceivable that the thermistor element and the resistive element are both resin-sealed as in Patent Document 2, and the sensor portion is configured. However, the thermistor element and the resistive element that are only connected by lead wires are sealed with the resin. When stopping, there is an inconvenience that misalignment is likely to occur in the resin and the responsiveness varies. In addition, since a lead wire such as a copper wire having a large diameter is directly attached to and connected to the thermistor element and the resistor element, heat dissipation through the lead wire is large and the accuracy of temperature detection is lowered. It was.

  The present invention has been made in view of the above-described problems, and suppresses variations in detection accuracy due to differences in temperature environment between elements, prevents positional deviation of the elements, reduces variations in responsiveness, and further leads. An object of the present invention is to provide a temperature sensor capable of limiting the heat dissipation due to the above and suppressing the decrease in detection accuracy.

  The present invention employs the following configuration in order to solve the above problems. That is, the temperature sensor of the present invention includes a chip-like thermistor element, a chip-like resistor element electrically connected to the thermistor element, and a circuit board on which the thermistor element and the resistor element are mounted on a wiring pattern on the surface. And a lead wire connected to the wiring pattern of the circuit board, and a sealing resin portion for sealing the thermistor element and the resistance element together with the circuit board.

  In this temperature sensor, since the circuit board on which the thermistor element and the resistance element are fixed is sealed in the sealing resin portion, the thermistor element and the resistance element are in the same temperature environment, and the detection accuracy can be stabilized. At the same time, there is no positional deviation of the elements, and variations in responsiveness are reduced. In addition, since the lead wires are connected via the circuit board, it is possible to limit the amount of heat dissipated by the lead wires having high thermal conductivity, thereby improving responsiveness and reducing variations. In particular, it is easy to set a wiring pattern on a circuit board to a narrow line width with high accuracy, and control of heat capacity and heat dissipation is easy. Furthermore, the circuit board size and the wiring pattern on the circuit board can be designed arbitrarily, and the fixing position of the thermistor element and the resistance element and the degree of freedom in wiring design are high.

  The temperature sensor of the present invention is characterized in that a gap is formed between the circuit board, the thermistor element, and the resistance element. That is, in this temperature sensor, since the air gap is formed between the circuit board, the thermistor element, and the resistance element, the static electricity charged in the thermistor element and the resistance element can be discharged into the air gap, and the electrostatic pressure resistance is improved. Can be made.

  In the temperature sensor of the present invention, the circuit board is a glass epoxy board or a polyimide flexible board. That is, in this temperature sensor, since the circuit board is formed of a glass epoxy board or a polyimide flexible board, it can be manufactured at low cost, and a wiring pattern can be easily formed with high accuracy.

The present invention has the following effects.
That is, according to the temperature sensor according to the present invention, since the circuit board to which the thermistor element and the resistance element are fixed is sealed in the sealing resin portion, variation in detection accuracy due to the temperature environment difference between the elements is suppressed. In addition, it is possible to reduce variations in responsiveness with no element displacement, and further, heat dissipation by the lead wire is limited by the circuit board, and a decrease in detection accuracy can be suppressed.

  Hereinafter, an embodiment of a temperature sensor according to the present invention will be described with reference to FIGS.

  As shown in FIGS. 1 and 2, the temperature sensor of the present embodiment includes a chip-like thermistor element 11, a chip-like resistor element 12 electrically connected to the thermistor element 11, the thermistor element 11, and a resistor. A sealing resin that seals the circuit board 14 together with the circuit board 14 on which the element 12 is mounted on the wiring pattern 13 on the surface, the lead wire 15 connected to the wiring pattern 13 on the circuit board 14, the thermistor element 11, and the resistance element 12. A voltage output type temperature sensor provided with a unit 16.

That is, this temperature sensor has a three-wire type voltage output configuration incorporating a temperature detection circuit composed of a thermistor element 11 and a resistance element 12, so that an output sensitivity proportional to the applied voltage is obtained, and a high output sensitivity and a constant temperature range are obtained. This achieves high linearization.
Examples of the thermistor element 11 include NTC type, PTC type, and CTR type thermistors. In this embodiment, an NTC type thermistor is used. The thermistor element 11 has electrode portions formed at both ends of the chip-like thermistor material, and the resistor element 12 also has electrode portions formed at both ends of the chip-like resistor material.

As the circuit board 14, a glass epoxy board, a polyimide flexible board, an alumina board, or the like is used. In particular, in the present embodiment, a glass epoxy board or a polyimide flexible board is used.
The wiring pattern 13 formed on the circuit board 14 is a patterned copper foil or the like. As shown in FIG. 3, the thermistor electrode pattern 17 for fixing the thermistor element 11 and the resistance element 12 are fixed. A resistance electrode pattern 18 and three lead wire electrode patterns 19a, 19b, and 19c for fixing one end of the lead wire 15 are provided. The lead wire electrode patterns 19a, 19b, and 19c serve as an input terminal (Vin), an output terminal (Vout), and a ground terminal (GND), respectively.

The wiring pattern 13 has a line width as narrow as possible in the pattern portions other than the thermistor electrode pattern 17, the resistance electrode pattern 18, and the lead wire electrode patterns 19a, 19b, and 19c.
The lead wire 15 is connected to lead wire electrode patterns 19a, 19b, 19c of an input terminal (Vin), an output terminal (Vout), and a ground terminal (GND), respectively.

  The temperature detection circuit in the temperature sensor of the present embodiment is configured to be an equivalent circuit shown in FIG. Various output characteristics can be realized by adjusting the resistance values of the resistance element 12 and the thermistor element 11, and output characteristics corresponding to the required detection temperature can be obtained. A high temperature accuracy can be obtained by matching and adjusting the resistance values of the thermistor element 11 and the resistance element 12. Further, in this temperature sensor, it is possible to select output of positive characteristics or negative characteristics with respect to voltage-temperature characteristics by a wiring method.

The sealing resin portion 16 is formed of, for example, an epoxy resin or the like, and a certain gap 20 is formed between the circuit board 14, the thermistor element 11, and the resistance element 12, as shown in FIG.
In other words, the thermistor element 11 and the resistance element 12 are arranged with the electrode portions on the thermistor electrode pattern 17 and the resistance electrode pattern 18, respectively, and are bonded and fixed by the conductive adhesive material 21 such as a solder material. The thermistor electrode pattern 17, the resistance electrode pattern 18 and the conductive adhesive material 21 are used to form a predetermined gap from the surface of the circuit board 14 so that a gap 20 is formed between the circuit board 14 and the thermistor element 11 and the resistance element 12. The thermistor element 11 and the resistance element 12 are fixed with a space therebetween.

The thermistor element 11 is fixed to the thermistor electrode pattern 17 disposed on the tip side of the circuit board 14, and the lead wire 15 is provided with electrode patterns 19 a, 19 b, disposed on the other end side of the circuit board 14. 19c.
The circuit board 14 is preferably a small size such as 0603 size from the viewpoint of good heat capacity and heat dissipation, and is preferably resin-molded as small as possible by the sealing resin portion 16.

In the temperature sensor of this embodiment, the temperature characteristics of the actually measured output voltage and the detection accuracy corresponding to the temperature are shown in FIGS. 5 and 6, respectively. FIG. 5 is a graph showing the output voltage ratio (Vout / Vin) with respect to temperature. FIG. 6 is a graph plotting the measured temperature calculated from the output voltage and showing the variation (accuracy).
As can be seen from FIGS. 5 and 6, a linear temperature characteristic of the output voltage is obtained, and a highly accurate measured value temperature is obtained.

  According to the temperature sensor of the present embodiment, the thermistor element 11 and the resistance element 12 are sealed in the sealing resin portion 16 together with the circuit board 14 to which the thermistor element 11 and the resistance element 12 are fixed. In addition, the detection accuracy can be stabilized, the element is not displaced, and the response variation is reduced. In addition, since the lead wires 15 are connected via the circuit board 14, the amount of heat dissipated by the lead wires 15 having high thermal conductivity can be limited, improving the responsiveness and reducing variations. . In particular, it is easy to set the wiring pattern 13 on the circuit board 14 to a narrow line width with high accuracy, and control of heat capacity and heat dissipation is easy. Furthermore, the circuit board size and the wiring pattern 13 on the circuit board 14 can be designed arbitrarily, and the fixing position of the thermistor element 11 and the resistance element 12 and the degree of freedom in wiring design are high.

Further, since the air gap 20 is formed between the circuit board 14 and the thermistor element 11 and the resistance element 12, static electricity charged in the thermistor element 11 and the resistance element 12 can be discharged into the air gap, and the electrostatic withstand voltage can be improved. Can be improved.
Further, since the circuit board 14 is formed of a glass epoxy board or a polyimide flexible board, the circuit board 14 can be manufactured at low cost, and the wiring pattern 13 can be easily formed with high accuracy.

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

  For example, although the thermistor element 11 and the resistance element 12 are used in the above embodiment, a circuit may be configured by combining a plurality of thermistor elements 11 or the resistance elements 12 and mounted on the same circuit board 14. I do not care. In this case, linearization in a wider temperature range is possible. Further, a circuit may be configured by mounting other electronic components on the circuit board 14.

It is sectional drawing along the circuit board surface which shows the temperature sensor of one Embodiment which concerns on this invention. It is a side view which shows the temperature sensor of this embodiment. In the temperature sensor of this embodiment, it is a top view which shows a circuit board. In the temperature sensor of this embodiment, it is an expanded sectional view in the mounting part of a thermistor element and a resistance element. 5 is a graph showing temperature characteristics of output voltage actually measured in the temperature sensor of the present embodiment. It is a graph which shows the accuracy of detection according to temperature in the temperature sensor of this embodiment. It is an equivalent circuit diagram showing a general temperature detection circuit using a thermistor.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Thermistor element, 12 ... Resistance element, 13 ... Wiring pattern, 14 ... Circuit board, 15 ... Lead wire, 16 ... Sealing resin part, 20 ... Air gap

Claims (3)

A chip-like thermistor element;
A chip-like resistance element electrically connected to the thermistor element;
A circuit board in which the thermistor element and the resistance element are mounted on a wiring pattern on the surface;
A lead wire connected to the wiring pattern of the circuit board;
A temperature sensor comprising: a sealing resin portion that seals the thermistor element and the resistance element together with the circuit board. The temperature sensor according to claim 1,
A temperature sensor, wherein a gap is formed between the circuit board, the thermistor element, and the resistance element. The temperature sensor according to claim 1 or 2,
The temperature sensor, wherein the circuit board is a glass epoxy board or a polyimide flexible board.

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