JPH0334285A - Organic positive property thermistor - Google Patents

Abstract

PURPOSE:To prevent a bending and an increase of resistance value of the whole body by dispersing a conductive threadlike substance to a sheet which consists of a material presenting a positive resistance temperature property made by dispersing conductive particles in an organic high polymer material. CONSTITUTION:In this organic positive property thermistor 11, the sheet 12 consists of a material presenting a positive resistance temperature property made by dispersing conductive particles to an organic high polymer material. At the upper side of the sheet 12, a pair of electrodes 13 and 14 with the form of comb teeth arranged in serting each other are formed. The electrodes 13 and 14 have feeders 13a and 14a along the side ends 12a and 12b of the sheet 12, and plural branch-form electrodes 13b and 14b. In the electrodes 13 and 14, two lines of metal wires 15 am 16 are used to stitch in the sheet 12 to form the one side electrode 13. The other side electrode 14 is also formed in the same manner. By such a composition, a bending or an increase of resistance value of the whole sheet body can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an organic positive temperature coefficient thermistor used, for example, as a planar heating element, and particularly to one having an improved electrode structure.

[Conventional technology]

Carbon black, organic polymer materials such as polyethylene,
A bottom-shaped sheet made by kneading conductive particles such as graphite or metal powder exhibits positive resistance-temperature characteristics. An organic positive temperature sensor using such a sheet has self-temperature control. It is often used as a sheet heating element. An example of the above-mentioned organic positive temperature coefficient thermistor is shown in FIG.

In the organic positive temperature coefficient thermistor 1, a pair of electrodes 3. is formed by printing and curing a conductive paste on one main surface of a sheet 2 made of a polyolefin resin such as polyethylene with conductive particles such as a carbon blank dispersed therein. 4 is formed. The electrodes 3 and 4 include power feeding portions 3a and 4a along the side edges of the sheet 2, and a plurality of branch-like electrodes extending from each power feeding portion toward the opposite power feeding portions 4a and 3a. 3b and 4b.

In the organic positive temperature coefficient thermistor 1, a plurality of branch electrodes 3b are formed by passing a current between the electrodes 3 and 4.

4b, the sheet 2 generates heat.

Although not particularly shown, a structure in which the electrodes 3.4 are made of metal foil is also known. That is, an organic positive temperature coefficient thermistor is also used in which a metal foil is punched out in the shape of the electrodes 3.4 and then attached to the sheet 2 with an adhesive, thermocompression bonding, or the like.

Furthermore, a structure has also been used in which only the power supply section is made of metal foil, and branch-like electrodes are formed by printing and curing conductive paste so as to extend from the metal foil toward the other power supply section. There is.

[Technical problem to be solved by the invention] In the organic positive temperature coefficient thermistor l in which the electrodes 3 and 4 are made of conductive paste, the electrode strength is weak, so if it repeatedly expands and contracts due to heat generation,
There were problems in that the sheet 2 was warped, and the electrodes were peeled off and disconnected. As a result, the resistance value increases,
In some cases, the desired amount of heat generation could not be obtained. In addition, when caulking or the like is performed when pulling out the terminals at the power feeding sections 3a, 4a, there is a problem in that the power feeding sections are likely to be disconnected.

On the other hand, in an example in which the entire electrode 3.4 is made of metal foil, the strength of the electrode itself is increased. Therefore, the terminal can be reliably attached to the power supply section by caulking or the like. Furthermore, since the strength of the branched wires i3b and 4b is sufficient, disconnection and the like are unlikely to occur.

However, since the thermal expansion coefficients of the metal foil and the resin constituting the sheet 2 differ by more than an order of magnitude, the deformation of the metal foil cannot follow the expansion and contraction of the sheet 2.

As a result, as the sheet 2 expands and contracts, the entire organic positive temperature coefficient thermistor l tends to warp, and in extreme cases, the warp may cause the electrodes made of metal foil to
Sometimes it peeled off from the surface.

Furthermore, even in a structure in which only the power supply parts 3a and 4a are made of metal foil and the branch electrodes 3b and 4b are made of conductive paste, due to the difference in thermal expansion between the metal foil and the sheet 2, the organic positive temperature coefficient thermistor l Warpage tends to occur throughout the product,
Similarly, electrode peeling was likely to occur. Not only 8M
Due to the difference in thermal expansion between the metal foil and the sheet, there was also a problem in that disconnection occurred between the electrically conductive paste portion provided on the metal foil and the branch electrode portion formed on the sheet.

Therefore, an object of the present invention is to provide an organic positive temperature coefficient thermistor that has high strength, has electrodes that can follow the expansion and contraction of the sheet, and can effectively prevent warping of the entire sheet and increase in resistance value. It is about providing.

(Means for Solving the Technical Problems) In the organic positive temperature sensor of the present invention, a sheet made of a material exhibiting positive resistance temperature characteristics in which conductive particles are dispersed in an organic polymer material, By sewing things together,
At least a pair of electrodes are formed on the sheet and spaced apart from each other by a predetermined distance.

Examples of the organic polymer material that can be used in the present invention include polyolefin resins such as polyethylene, but other organic polymer materials that can serve as a carrier in which the conductive particles described below can be dispersed Any one can be used.

As the conductive particles, particles made of any conductive material such as carbon black, graphite, or metal powder can be used. Normally, a sheet is obtained by kneading conductive particles into an organic polymeric material and forming a bottom shape using an appropriate acid forming method, but it is also possible to laminate a film made of the kneaded material on a plate-shaped insulating member. A sheet may be formed by doing this.

As the conductive filamentous material for forming the electrode, various conductive materials such as single or bundled metal wires, bundles of metal fibers, composites of metal fibers and organic fibers, or carbon fibers can be used. Can be used. In addition, "thread-like material" is a term chosen to express something that can be sewn onto a sheet, and thin tape bodies are also included in the expression "thread-like material" as long as they can be sewn onto a sheet. I would like to point this out.

When sewing the conductive thread-like material into the sheet, a known sewing device such as a sewing machine can be used, but the sewing method itself is arbitrary.

[Operation] Since at least one pair of electrodes is formed by being sewn onto a sheet made of a material exhibiting positive resistance-temperature characteristics, the bonding strength between the sheet and the electrodes is dramatically increased. Therefore, warping is less likely to occur due to expansion and contraction of the sheet, and even if warping occurs, electrode peeling and the like are less likely to occur. Furthermore, since it is a thread-like material and is made of a material that can be sewn onto a sheet, breakage due to bending or the like is unlikely to occur.

[Explanation of Examples]

FIG. 1 is a plan view of a first embodiment of the invention.

In the organic positive temperature coefficient thermistor 11, the sheet 12 is constructed by dispersing carbon blank in polyethylene.

A pair of comb-like electrodes 13 and 14 are formed on the upper surface of the sheet 12 and are interposed with each other. That is, the electrodes 13, 14 are connected to the side edges 1 of the sea
2a, 12b, and a plurality of branch-like electrode parts 13b14b.

A feature of this embodiment is that the electrodes 13 and 14 are constructed by sewing conductive threads onto the sheet 12. That is, as shown in an enlarged sectional view of the main part in FIG. 3, one electrode 13 is formed by sewing two pieces of gold yAvA15.16 into the sheet 12. The other electrode 14 is also formed in the same manner as the electrode 13. The electrodes 13 and 14 are sewn in using a general sewing machine such as a sewing machine, but the method itself is not particularly limited thereto.

In this embodiment, all parts of the pair of electrodes 13 and 14 are constructed by sewing metal wires, so that the electrodes 13 and 14 can be easily and efficiently assembled using a sewing machine such as a sewing machine.
3.14 can be formed. Therefore, as in the conventional example using both conductive paste and metal foil? ! It is believed that the complicated electrode forming process can be greatly simplified.

Furthermore, since the conductive filament can be formed from a relatively inexpensive base metal, the material cost can be reduced compared to the case where an expensive noble metal material such as Ag paste is used. Furthermore, it is also possible to omit complicated steps such as a drying step when applying a conductive paste and an etching step when forming a TL pole made of metal foil. Therefore, the i-electrode formation cost can be effectively improved.

In the organic positive temperature coefficient thermistor 11 of the embodiment shown in FIG.
3.14 is sewn into the sheet 12, and the IT electrode 13
The bonding strength between the sheet 14 and the sheet 12 is higher than that of sewing. Therefore, even if the sheet 12 expands or contracts when it generates heat, the electrodes are unlikely to peel off, and since they are filamentous and movable, they are unlikely to warp.

Moreover, in this embodiment, two metal wires 15 and 16 are used and are sewn from both sides of the sheet 12, so that the force from the electrodes is applied equally to both sides of the sheet 12 when it expands and contracts. It is believed that it is possible to more effectively reduce warpage. Furthermore, since the electrodes are sandwiched between threads from both sides, it is even more difficult for the electrodes to peel off.

Furthermore, since the electrodes 13 and 14 are made of conductive filaments, they are less likely to break due to bending, etc., compared to electrodes made of conductive paste, and even if one metal wire breaks, two metal wires Electrical continuity is maintained by one remaining metal wire, lines 15,16. Therefore, reliability against electrode disconnection is also improved.

FIG. 4 is a plan view of an organic positive temperature coefficient thermistor according to a second embodiment of the present invention. In the organic positive temperature coefficient thermistor 21, power supply electrodes 22 and 23 made of metal foil are formed along each side Oiu12a and 12b of the sheet 12. After forming the power supply electrodes 22.23, electrodes 13.14 made of conductive threads are then sewn into the sheet 12. Therefore, the power supply section is connected to the power supply! An electrode 22.23 and a conductive filament which is sewn onto the power supply electrode 22.23.
3a and 14a. The rest of the structure is the same as the embodiment shown in FIG.

In this embodiment, since the power feeding part is composed of both the conductive thread-like material and the power feeding electrodes 22 and 23 made of metal foil, the current capacity is increased, and the terminal for connection with the outside can be caulked. Attachment is said to be easy.

Moreover, the power supply electrodes 22 and 23 made of metal foil are
Since the power supply electrodes 22 and 23 are sewn together with the conductive thread-like material, peeling of the power supply electrodes 22 and 23 made of metal foil is also less likely to occur compared to the case of conventional electrodes made of metal foil.

Note that the material constituting the power supply electrodes 22 and 23 is not limited to metal foil, but any conductive tape-like material can be used.

In the embodiments of FIGS. 1 and 4, a pair of comb-shaped electrodes were formed on the sheet, but the electrode shape of the organic positive temperature coefficient thermistor to which the present invention is applied is the pair of comb-shaped electrodes as described above. It is not limited to those with electrodes formed thereon. That is, the present invention can also be applied to electrodes having various planar shapes shown by two-dot chain lines in the schematic plan views shown in FIGS. 5(a) to 5(c).

In FIG. 5(a), a pair of electrodes 13, 14 are connected to the sheet 12.
They are arranged in a spiral shape. In FIG. 5(b), the pair of electrodes 13, 14 are configured to have spiral electrode portions 13c, 14c that are inserted into each other. Furthermore, in FIG. 5(C), a plurality of pairs of comb-like electrode-shaped branch electrode parts 13d and 14d are formed between the power supply parts 13a and 143.

〔Effect of the invention〕

According to the present invention, since the electrodes are formed by sewing conductive threads into the sheet, it is possible to obtain an organic positive temperature coefficient thermistor in which the bonding strength between the sheet and the electrodes is dramatically increased. Therefore, the sheet is less likely to warp when heat is generated, and electrode peeling and t-pole disconnection are less likely to occur.
The reliability of organic positive temperature coefficient thermistors can be effectively increased.

Moreover, since the i-pole can be constructed simply by sewing thread-like material,
This can also contribute to simplifying the electrode forming process and reducing costs.

Note that if a conductive filament having a relatively high resistance value is used, it is possible to utilize the heat generated by the electrode itself, and therefore the heat generating area can be expanded.

[Brief explanation of drawings]

FIG. 1 is a plan view of an organic positive temperature coefficient thermistor according to an embodiment of the present invention, and FIG. 2 is a plan view of a conventional organic positive temperature coefficient thermistor.
FIG. 3 is a sectional view showing an enlarged main part of an organic positive temperature coefficient thermistor, FIG. 4 is a plan view of an organic positive temperature coefficient thermistor according to a second embodiment of the present invention, and FIGS. 5(a) to (c). 2A and 2B are schematic plan views for explaining modified examples of electrode shapes. In the figure, 11 is an organic positive temperature coefficient thermistor, 12 is a sheet, 13.14 is an electrode, 13a, 14a are a power supply part, 13
Reference numerals b and 14b indicate branched 'f' electrodes, and reference numerals 15 and 16 indicate metal wires for forming the electrodes. Figure 3 Figure 2 Figure 4 3 0 Figure 3 (b) 1.C 3 3c 3d Discharge

Claims (1)

[Scope of Claims] A sheet made of a material exhibiting positive resistance-temperature characteristics in which conductive particles are dispersed in an organic polymer material, and a conductive thread-like material is sewn onto the sheet, and the An organic positive temperature coefficient thermistor comprising at least a pair of electrodes arranged on a sheet at a predetermined distance apart.