JP2017026415A - Temperature sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a temperature sensor which obtains a joining property of sufficient strength in wiring connection, and can be used for high-temperature purpose.SOLUTION: A temperature sensor is equipped with a flexible wiring board 2 in which pattern wiring 2b is formed on an insulation base film 2a; and a sensor portion 3 connected to the flexible wiring board. The sensor portion is equipped with an insulation film 5 adhered with the flexible wiring board on one side surface; a thin film thermister portion 6 pattern-formed by thermister material on the insulation film; a pair of comb-shaped electrodes 7 pattern-formed on the thin film thermister portion oppositely to each other; and a pair of pattern electrodes 8 connected with the pair of the comb-shaped electrodes and the pair of the pattern wiring and pattern-formed on the one side surface of the insulation film. A through-hole 2c is formed on the pattern wiring of the insulation base film, and the pattern wirings and the pattern electrodes exposed in the through-hole are welded.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a temperature sensor suitable for measuring the temperature of a heating roller such as a copying machine or a printer.

Generally, a heating sensor used in a copying machine or a printer is provided with a temperature sensor in contact with the heating roller in order to measure its temperature. As such a temperature sensor, for example, in Patent Document 1, a pair of lead frames, a thermal element disposed and connected between the lead frames, and a holding portion formed at an end portion of the pair of lead frames. Has been proposed.
In Patent Document 1, a thin film thermistor in which a heat sensitive film is formed on one surface of an insulating substrate such as alumina is employed in addition to a bead thermistor and a chip thermistor as a heat sensitive element.

  In recent years, a temperature sensor in which a thin film thermistor is formed on an insulating film has been developed as a film-type temperature sensor that is excellent in flexibility and can be thinned as a whole. For example, Patent Document 2 discloses a temperature sensor including a pair of lead frames, a sensor unit connected to the pair of lead frames, and an insulating holding unit fixed to the pair of lead frames to hold the lead frame. Has been proposed.

  In this temperature sensor, the sensor unit has an insulating film, a thin film thermistor portion patterned with the thermistor material on the surface of the insulating film, and a plurality of comb portions above and below the thin film thermistor portion. A pair of comb electrodes patterned to face each other, and a pair of pattern electrodes connected to the pair of comb electrodes and patterned on the surface of the insulating film. A thin film thermistor portion is extended and bonded to the surface of the film, and is connected to a pair of pattern electrodes.

JP 2000-74752 A JP 2014-52228 A

The following problems remain in the conventional technology.
That is, in the above conventional technology, the lead frame and the electrode are connected by solder, conductive resin adhesive or welding. However, when used in high temperature applications, the solder and the conductive resin adhesive have stable bondability. Therefore, the connection is made by welding. However, in the case of the flexible thermistor described in Patent Document 2, since the pattern electrode of the metal film connected to the lead frame such as SUS is thin, there is a possibility that the joint strength becomes insufficient when spot welding is performed. . For example, in the case of joining a lead frame having a thickness of about 0.1 mm and a pattern electrode having a thickness of about 5 μm, the difference between the thicknesses is too great to achieve welding with good joint strength.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a temperature sensor that can obtain sufficient strength in wire connection and can be used even in high-temperature applications.

  The present invention employs the following configuration in order to solve the above problems. That is, a temperature sensor according to a first aspect of the present invention includes a flexible wiring board in which a pair of pattern wirings is formed on one surface of an insulating base film, and a sensor unit connected to the flexible wiring board, The sensor unit includes an insulating film having the flexible wiring board bonded to one surface thereof, a thin film thermistor portion patterned with a thermistor material on one surface of the insulating film, and upper and lower portions of the thin film thermistor portion. A pair of comb-shaped electrodes having a plurality of comb portions on at least one of them and patterned to face each other, and one surface of the insulating film connected to the pair of comb-shaped electrodes and the pair of pattern wirings And a pair of pattern electrodes patterned, and a through hole is formed on the pattern wiring of the insulating base film. An exposed portion of the said pattern wiring and said pattern electrode is characterized in that it is welded to the inside.

  In this temperature sensor, a through hole is formed on the pattern wiring of the insulating base film, and the pattern wiring and the pattern electrode exposed in the through hole are welded. In addition, since both of the patterns formed and welded with the metal foil have the same thickness level, sufficient joint strength can be obtained even with spot welding. In addition, since a flexible flexible wiring board is used as a member for connecting the sensor unit, it is possible to make the whole temperature sensor softer than when using a lead frame, and it is pressed against the object to be measured and brought into contact with it. In this case, it is difficult to damage the measurement object such as a heating roller, and high adhesion to the measurement object can be obtained.

A temperature sensor according to a second invention is the temperature sensor according to the first invention, wherein one end side of the pressing pressure adjusting member is bonded to the other surface of the insulating film, and the pressing pressure adjusting member is along the flexible wiring board. It is characterized by extending.
That is, in this temperature sensor, one end of the pressing pressure adjusting member is bonded to the other surface of the insulating film, and the pressing pressure adjusting member extends along the flexible wiring board. Since the rigidity of the pressing pressure adjusting member is added as compared with the case where only the wiring board is connected and held, it is possible to press the measuring object more strongly.

The temperature sensor according to a third aspect of the present invention is the temperature sensor according to the first or second aspect, wherein at least the welded portion of the pattern wiring is a Cu layer formed on one surface of the insulating base film, and the Cu And a Ni layer formed on the layer.
That is, in this temperature sensor, at least a portion to be welded of the pattern wiring has a Cu layer formed on one surface of the insulating base film and a Ni layer formed on the Cu layer. High weldability of welding can be obtained.

The present invention has the following effects.
That is, according to the temperature sensor according to the present invention, the through hole is formed on the pattern wiring of the insulating base film, and the pattern wiring exposed in the through hole and the pattern electrode are welded. Sufficient joint strength can be obtained even by welding.
Therefore, according to the temperature sensor of the present invention, it can be used even in high temperature applications and is suitable for measuring the temperature of a heating roller of a copying machine, a printer or the like.

It is a top view which shows 1st Embodiment of the temperature sensor which concerns on this invention. It is the sectional view on the AA line of FIG. In 1st Embodiment, it is a top view which shows a sensor part. In 1st Embodiment, it is the top view (a) which shows a thin film thermistor part formation process, the top view (b) which shows an electrode formation process, and a protective film formation process (c). It is sectional drawing which shows 2nd Embodiment of the temperature sensor which concerns on this invention.

  Hereinafter, a temperature sensor according to a first embodiment of the present invention will be described with reference to FIGS. Note that in some of the drawings used for the following description, the scale is appropriately changed as necessary to make each part recognizable or easily recognizable.

  The temperature sensor 1 of the present embodiment is, for example, a temperature detection sensor for a heating roller of a copying machine. As shown in FIGS. 1 to 3, a pair of pattern wirings 2b are provided on one surface of an insulating base film 2a. A pattern-formed flexible wiring board 2 and a sensor unit 3 connected to the flexible wiring board 2 are provided.

The sensor unit 3 includes an insulating film 5 having a flexible wiring board 2 bonded to one surface, a thin film thermistor portion 6 patterned with a thermistor material on one surface of the insulating film 5, and a thin film thermistor portion 6. One of the insulating films 5 connected to a pair of comb-shaped electrodes 7 having a plurality of comb portions 7a thereon and patterned to face each other, a pair of comb-shaped electrodes 7 and a pair of pattern wirings 2b And a pair of pattern electrodes 8 patterned on the surface.
In the present embodiment, the direction in which one surface of the insulating base film 2a faces is referred to as the downward direction, and the direction in which the other surface of the insulating base film 2a faces is referred to as the upward direction. Accordingly, one surface of the insulating base film 2a faces downward, and one surface of the insulating film 5 faces upward and faces each other.

A through hole 2c penetrating the other surface is formed on the pattern wiring 2b of the insulating base film 2a. The through hole 2c has a long hole shape along the extending direction of the pattern wiring 2b and is formed on each pattern wiring 2b.
The pattern wiring 2b exposed in the through hole 2c and the underlying pattern electrode 8 are spot welded. For example, in this embodiment, two spot welds 2d are formed in each of the pair of through holes 2c.

The flexible wiring board 2 is a so-called copper-clad film (CCL), for example, copper on one surface of an insulating base film 2a formed of polyimide, PEN (polyethylene naphthalate), PET (polyethylene terephthalate), or the like. The pattern wiring 2b of foil is patterned.
The insulating base film 2a is formed in a strip shape, and the pair of pattern wirings 2b extend parallel to each other along the insulating base film 2a.

At least a spot welded portion of the pattern wiring 2b has a Cu layer formed on one surface of the insulating base film 2a and a Ni layer formed on the Cu layer. This Ni layer is formed by Ni plating on the Cu layer.
In the temperature sensor 1 of the present embodiment, an insulating protective film 10 that covers the pattern electrode 8, the thin film thermistor portion 6, and the comb electrode 7 excluding the pad portion 8 a is formed on the insulating film 5.

  The said insulating film 5 is made into the substantially rectangular shape, for example, is formed in strip | belt shape with the polyimide resin sheet of thickness 7.5-125 micrometers. The insulating film 5 can be made of PET: polyethylene terephthalate, PEN: polyethylene naphthalate, or the like, but a polyimide film is desirable for measuring the temperature of the heating roller because the maximum use temperature is as high as 230 ° C.

The thin film thermistor portion 6 is disposed on the base end side of the insulating film 5 and is formed of, for example, a TiAlN thermistor material. In particular, the thin film thermistor section 6 is a metal represented by the general formula: Ti _x Al _y N _z (0.70 ≦ y / (x + y) ≦ 0.95, 0.4 ≦ z ≦ 0.5, x + y + z = 1). It consists of nitride and its crystal structure is a hexagonal wurtzite single phase.

The pattern electrode 8 and the comb-shaped electrode 7 are formed on the thin film thermistor portion 6 with a thickness of 5 to 100 nm of a Cr or NiCr bonding layer and a noble metal such as Au on the bonding layer with a thickness of 50 to 1000 nm. And an electrode layer formed.
In the middle of the pair of pattern electrodes 8, as shown in FIG. 3, a pair of wide pad portions 8a corresponding to the pattern wiring 2b is provided.
The pair of comb-shaped electrodes 7 has a comb-shaped pattern in which the comb portions 7a are alternately arranged so as to face each other.

The comb portion 7 a extends along the extending direction of the insulating film 5. That is, when the back surface side of the insulating film 5 (the other surface side where the thin film thermistor portion 6 is not formed) is pressed against a rotating heating roller to measure the temperature, the extending direction of the insulating film 5 Therefore, the thin film thermistor portion 6 is also bent in the same direction. At this time, since the comb portion 7a extends in the same direction, the thin film thermistor portion 6 is reinforced, and generation of cracks can be suppressed.
The protective film 10 is an insulating resin film or the like, for example, a polyimide film having a thickness of 20 μm is employed.

A method for manufacturing the temperature sensor 1 will be described below with reference to FIGS.
The manufacturing method of the temperature sensor 1 according to this embodiment includes a thin film thermistor portion forming step of patterning the thin film thermistor portion 6 on the surface of the insulating film 5 and a pair of opposed comb electrodes 7 disposed on the thin film thermistor portion 6. Then, an electrode forming step of forming a pair of pattern electrodes 8 on the surface of the insulating film 5, a protective film forming step of forming the protective film 10 on the insulating film 5, and the flexible wiring board 2 on the sensor unit 3. And a wiring board connecting step for connection.

As a more specific example of the manufacturing method, a reactive sputtering method is performed in a nitrogen-containing atmosphere using a Ti—Al alloy sputtering target on the insulating film 5 (on one surface) of a polyimide film having a thickness of 50 μm. _{Te, Ti x Al y N z (} x = 0.09, y = 0.43, z = 0.48) is formed by a thermistor film thickness 200nm of. The sputtering conditions at that time were an ultimate vacuum of 5 × 10 ⁻⁶ Pa, a sputtering gas pressure of 0.4 Pa, a target input power (output) of 200 W, and a nitrogen gas fraction of 20 in a mixed gas atmosphere of Ar gas + nitrogen gas. %.

A resist solution is applied onto the deposited thermistor film with a bar coater, pre-baked at 110 ° C. for 1 minute and 30 seconds, exposed to light with an exposure device, and unnecessary portions are removed with a developer, and further at 150 ° C. for 5 minutes. Patterning is performed by post-baking. Thereafter, the thermistor film unnecessary Ti _x Al _y N _z by wet etching in a commercial Ti etchant, as shown in FIG. 4 (a), to a thin film thermistor portion 6 of a desired shape on the resist stripping.

Next, a 20-nm-thick Cr film bonding layer is formed on the thin film thermistor portion 6 and the insulating film 5 by sputtering. Further, an Au film electrode layer is formed to a thickness of 200 nm on this bonding layer by sputtering.
Next, after applying a resist solution on the electrode layer formed with a bar coater, pre-baking is performed at 110 ° C. for 1 minute 30 seconds, and after exposure with an exposure apparatus, unnecessary portions are removed with a developing solution, Patterning is performed by post-baking for 5 minutes. Thereafter, unnecessary electrode portions are wet-etched in the order of a commercially available Au etchant and Cr etchant, and as shown in FIG. 4B, desired comb electrodes 7 and pattern electrodes 8 are formed by resist stripping. .

Furthermore, a polyimide varnish is applied to the surface of the insulating film 5 by a printing method and cured at 180 ° C. for 30 minutes. As shown in FIG. 4C, the polyimide protective film 10 having a thickness of 20 μm is obtained. Form.
Next, Ni plating is performed on a wide region to be the pad portion 8a to form the pad portion 8a.
When a plurality of sensor units 3 are manufactured simultaneously, a plurality of thin film thermistor units 6, comb electrodes 7, pattern electrodes 8, protective films 10 and pad units 8a are formed on a large sheet of insulating film 5 as described above. After that, each sensor unit 3 is cut from the large sheet.

Next, as shown in FIGS. 1 and 2, the flexible wiring board 2 is bonded to the pair of pad portions 8a by spot welding.
First, before spot welding, a pair of long hole-like through holes 2c reaching the pair of pattern wirings 2b are formed in the insulating base film 2a of the flexible wiring board 2 in advance by etching or the like. The pattern wiring 2b is composed of a metal film including a Cu layer having a thickness of 18 μm and a Ni layer having a thickness of 5 μm. As the pattern wiring 2b, a Cu layer having a thickness of 5 to 50 μm and a Ni layer having a thickness of 1 to 20 μm can be employed.

  And the pattern wiring 2b exposed in the through-hole 2c and the pad part 8a are spot-welded in a state where the pattern wiring 2b immediately below the through-hole 2c is placed on the pad part 8a. Therefore, the flexible wiring board 2 and the sensor part 3 are connected by the spot weld part 2d, and the temperature sensor 1 shown in FIG.1 and FIG.2 is produced. When spot welding is performed, the flexible wiring board 2 and the sensor unit 3 may be temporarily fixed with an adhesive or the like.

Thus, in the temperature sensor 1 of this embodiment, the through-hole 2c is formed on the pattern wiring 2b of the insulating base film 2a, and the pattern wiring 2b and the pattern electrode 8 exposed in the through-hole 2c are welded. Therefore, both the pattern wiring 2b and the pattern electrode 8 are patterned and welded with metal foil, and both are set to the same thickness level, so that sufficient bonding strength can be obtained even with spot welding. .
Further, the overall thickness can be reduced as compared with the case of connecting the lead frame.

In addition, since the flexible flexible wiring board 2 is used as a member for connecting the sensor unit 3, it is possible to make the whole temperature sensor softer than the case where a lead frame is used, and it is pressed against the object to be measured for contact. In this case, it is difficult to damage the measurement object such as a heating roller, and high adhesion to the measurement object can be obtained.
Furthermore, since the part to be welded of the pattern wiring 2b has a Cu layer formed on one surface of the insulating base film 2a and a Ni layer formed on the Cu layer, welding with high welding is performed. Sex can be obtained.

  Next, a second embodiment of the temperature sensor according to the present invention will be described below with reference to FIG. In the following description of each embodiment, the same constituent elements 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 the sensor section 3 is supported only by the flexible wiring board 2 in the first embodiment, whereas the temperature sensor 21 of the second embodiment has a sensor. The point 3 is that not only the flexible wiring board 2 but also a pair of pressing pressure adjusting members 22 are connected to support the sensor unit 3.
That is, in the second embodiment, one end side of the pair of pressing pressure adjusting members 22 is bonded to the other surface of the insulating film 5, and the pair of pressing pressure adjusting members 22 extends along the flexible wiring board 2. doing. In the present embodiment, a pair of pressing pressure adjusting members 22 are provided to face the pair of pattern wirings 2b.

As the pressing pressure adjusting member 22, for example, a SUS rod-like member or a plate-like member can be adopted.
The pressing pressure adjusting member 22 is bonded to the insulating film 5 with an adhesive or the like, and the other end portion is held by the insulating holding portion 24 together with the other end portion of the flexible wiring board 2.
In the first embodiment, the sensor unit 3 can be connected and held only by the flexible wiring board 2, so that the whole can be a softer temperature sensor, but in the second embodiment, the temperature is only obtained by the flexible wiring board 2. This is employed when the rigidity of the entire sensor is insufficient, and the rigidity is improved by reinforcing with the pressing pressure adjusting member 22.

  As described above, in the temperature sensor 21 of the second embodiment, one end side of the pressing pressure adjusting member 22 is bonded to the other surface of the insulating film 5, and the pressing pressure adjusting member 22 extends along the flexible wiring board 2. Since the rigidity of the pressing pressure adjusting member 22 is added compared to the case where the sensor unit 3 is connected and held only by the flexible wiring board 2, the sensor unit 3 may be pressed more strongly against the measurement object. It becomes possible.

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 the second embodiment, the holding portion that holds the flexible wiring board is provided. However, in the first embodiment, the flexible wiring board may be held by the holding portion.

  DESCRIPTION OF SYMBOLS 1,21 ... Temperature sensor, 2 ... Flexible wiring board, 2a ... Insulating base film, 2b ... Pattern wiring, 2c ... Through-hole, 2d ... Spot welding part, 3 ... Sensor part, 5 ... Insulating film, 6 ... Thin film Thermistor part, 7 ... comb electrode, 7a ... comb part, 8 ... pattern electrode, 22 ... pressing pressure adjusting member

Claims (3)

A flexible wiring board in which a pair of pattern wirings is formed on one surface of the insulating base film, and a sensor unit connected to the flexible wiring board,
The sensor part is an insulating film in which the flexible wiring board is bonded to one surface;
A thin film thermistor portion patterned with a thermistor material on one surface of the insulating film;
A pair of comb-shaped electrodes that have a plurality of comb portions on at least one of the upper and lower sides of the thin film thermistor portion and are patterned to face each other;
A pair of pattern electrodes connected to the pair of comb-shaped electrodes and the pair of pattern wirings and patterned on one surface of the insulating film;
A through hole is formed on the pattern wiring of the insulating base film,
The temperature sensor, wherein the pattern wiring exposed in the through hole and the pattern electrode are welded. The temperature sensor according to claim 1,
One end side of the pressing pressure adjusting member is bonded to the other surface of the insulating film,
The temperature sensor, wherein the pressing pressure adjusting member extends along the flexible wiring board. The temperature sensor according to claim 1 or 2,
At least the part to be welded of the pattern wiring has a Cu layer formed on one surface of the insulating base film and a Ni layer formed on the Cu layer. Temperature sensor.

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