JP5061769B2 - Planar heating element - Google Patents

Description

  The present invention relates to a planar heating element, particularly in the vicinity of a terminal.

  In a conventional sheet heating element, the lead wire is bonded to the terminal of the electrode. The entire sheet heating element including the electrode, the resistor, and the terminal formed by previously forming solder on the surface to which the lead wire is connected is used. After covering with an exterior material, there exist some which melt | dissolve an exterior material thermally to form an opening part, and simultaneously join an electrode, a terminal, and a lead wire (for example, refer patent documents 1 and 2).

  FIG. 7 shows a conventional planar heating element described in the publication. As shown in FIG. 7, a pair of electrodes 2 is disposed on a polyethylene terephthalate film 1, and a resistor 3 having a positive resistance temperature characteristic is disposed on the electrode 2. Terminals 4 are formed on the power feeding portions of the electrodes 2, and the entire substrate 1 on which the electrodes 2 and the resistors 4 are formed is covered with an exterior material 6 in which a heat-meltable resin film is laminated on a polyethylene terephthalate film. Has been. The terminal 4 is formed with a heat-melting bonding metal 7 made of solder, the lead wire is formed with a heat-melting bonding metal 8, and the bonding metal 7 and the bonding metal 8 are formed in holes penetrating the exterior material 6. The terminal 4 and the lead wire 9 are electrically and physically connected to each other.

Further, generally, an insulating resin is molded so as to cover a hole penetrating the exterior material 6 to ensure insulation between the terminal 4 and the lead wire 9 and the outside.
JP 2005-149877 A JP-A-2005-302301

  However, since the conventional planar heating element is based on the premise that the terminal is completely bonded to the electrode, high quality control is required. Further, from the viewpoint of long-term reliability, the terminal, electrode, and electrical insulation are required. There has been a concern that the adhesion between the terminal and the electrode may be incomplete due to material deterioration of the coated base material.

  Assuming a state in which the terminal is not completely bonded to the electrode, the bonded portion may slightly contact within a very narrow range, and the contact resistance may become very large. Since a large current flows through the connecting portion between the terminal and the electrode, it is overheated due to an increase in contact resistance. When the electrically insulating substrate is a resin material such as PET, it can be considered that it melts and further carbonizes. At this time, since the temperature of the electrically insulating substrate around the fine contact portion of the terminal also becomes high at the same time, the electrically insulating substrate shrinks, while the contracted electrically insulating substrate carbonizes and forms a new conduction path. Conduction will continue, and the carbonized part will expand. Due to such a series of cycles of contraction of the electrically insulating base material and expansion of carbonization, there has been a problem that the microcontact portion of the terminal is kept overheated and there is a risk of damaging the peripheral members.

  Generally, it is used to surround a place where there is a risk of overheating with a non-combustible material such as metal or mica, but in this case, the carbonized part spreads and the whole must be surrounded with a non-combustible material. was there.

  SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems, and an object of the present invention is to make a conduction disabled state safe even when the contact resistance between a terminal and an electrode increases.

In order to solve the above-described conventional problems, the planar heating element of the present invention includes an electrically insulating substrate made of a resin material such as polyethylene terephthalate , a lead wire for supplying power, and the electrically insulating substrate. A pair of electrodes disposed on the electrode, a terminal for electrically connecting the electrode and the lead wire, and a resistor that generates heat by applying a voltage by the electrode, covering at least the terminal and covering the electric A planar heating element comprising an insulating insulating base material and an electrically insulating covering base material bonded to the insulating base material, wherein the thermal insulating shrinkage suppression means of the electrical insulating base material covering the terminal and the vicinity of the terminal is used as the planar heating element. It is set as the structure with which the said electrically insulating base material side was equipped.

  The contact resistance between the terminal and the electrode is very large by providing the surface of the electrically insulating base material covering the terminal and the vicinity of the terminal and providing the means for suppressing the thermal expansion and contraction of the electrically insulating base material on the surface of the electrically insulating base material. Therefore, when it becomes an overheated state, it will suppress that an electrically insulating base material shrink | contracts, and it becomes impossible for an electrically insulating base material to form a new conduction | electrical_connection path, expanding a carbonization part. Since a new conduction path is not formed by the carbide of the electrically insulating base material, the terminal and the electrode are insulated by fusing the electrically insulating base material, making it impossible to safely conduct without maintaining the overheating state. be able to.

  In particular, in the present invention, by suppressing the thermal expansion and contraction of the electrically insulating base material and realizing a non-conductive state, the main purpose is to end the overheated state in a very short time. The intended action is significantly different from the configuration of covering the periphery of the part and reducing the influence on the peripheral member.

  According to the planar heating element of the present invention, it is possible to provide a state in which conduction is impossible safely even when the contact resistance between the terminal and the electrode increases.

According to a first aspect of the present invention, there is provided an electrically insulating substrate made of a resin material such as polyethylene terephthalate , a lead wire for supplying power, a pair of electrodes disposed on the electrically insulating substrate, and the electrodes And a terminal for electrical connection of the lead wire, and a resistor that generates heat by applying a voltage by the electrode, and covers at least the terminal and is adhered to the electrically insulating substrate A sheet heating element comprising a substrate, wherein the terminal and the electrically insulating substrate covering the vicinity of the terminal are provided with thermal expansion / shrinkage suppression means on the sheet insulating element side of the sheet heating element. It is. As a result, the contact resistance between the terminal and the electrode becomes very large, and even if it becomes overheated, the electrically insulating base material will not shrink, so it cannot be safely conducted without maintaining the overheated state. It can be in a state.

  The second invention is provided with a means for suppressing thermal expansion / shrinkage of the electrically insulating coating material on the side of the electrically insulating coating material of the planar heating element in addition to the means for suppressing thermal expansion / shrinkage on the side of the electrically insulating substrate. is there. As a result, the contact resistance between the terminal and the electrode becomes very large, and the electrically insulating coating material does not shrink even when overheated, so that the carbide generated from the electrically insulating coating material is reduced. Since the transition to the electrically insulating base material and no formation of a new conduction path is eliminated, it is possible to make the state incapable of conducting safely without maintaining the overheating state. Therefore, it is particularly useful when the electrically insulating coating material is easily carbonized.

  The third invention uses an electrically insulating tape covering the thermal expansion / shrinkage suppression means in addition to the thermal expansion / shrinkage suppression means. In particular, when the thermal expansion / shrinkage suppression means is not electrically insulating, the planar heat generating body is safer in terms of insulation than the second aspect of the present invention by providing electrical insulation with an electrical insulating tape.

The fourth invention uses a thermal expansion / shrinkage suppression tape having rigidity and nonflammability as means for covering the terminals and the vicinity of the terminals and suppressing thermal expansion / contraction of the electrically insulating substrate. In particular, since the object of the present invention can be provided in a tape shape, the thin shape of the terminal portion can be maintained. Since the thin shape can be maintained, the present invention can provide a planar heating element that can be used in a wide range of applications. By using an appropriate tape material and area, when the thermal expansion / shrinkage suppression tape is also applied to the surface of the electrically insulating coating substrate, the lead wire can be fixed simultaneously. In addition, since the object of the present invention can be provided by simply attaching a tape, it can be manufactured at low cost in terms of material cost and man-hour.

  5th invention uses an electrically insulating resin for the means which covers the vicinity of a terminal and a terminal, and suppresses thermal expansion and contraction of an electrically insulating base material. At the same time as achieving the object of the present invention, by using an electrically insulating resin, electrical insulation is also provided at the same time, and a double-coated structure is provided on the surface of the electrically insulating substrate, thereby providing a more electrically safe structure. It becomes. In addition, since an electrically insulating resin is used, a relatively complicated shape can be obtained by using a simple mold. Furthermore, when the electrically insulating resin base material is applied to the surface of the electrically insulating coated base material, the electrically insulating resin is in a molten state until it is cured. It can be easily covered, and at the same time, it can rationally provide electrical insulation in the vicinity of the power feeding part, and by using an appropriate electrical insulating resin, the weather resistance of the power feeding part can be improved and the lead wire can be fixed simultaneously. It is possible and still better.

  In the sixth invention, the thermal expansion / shrinkage suppression tape is made of a tape base material and an adhesive material having high thermal conductivity. By using a metal foil with high thermal conductivity, it is possible to soak and heat diffuse the overheated location, simultaneously providing the effect of suppressing melting and carbonization of the electrically insulating base material or the electrically insulating coated base material it can.

  The seventh invention uses a thermoplastic hot melt adhesive for the electrically insulating resin. By using a thermoplastic hot melt adhesive, the time until resin curing can be shortened, and a planar heating element excellent in productivity can be provided.

  In the eighth invention, a two-component curable resin is used as the electrically insulating resin. The two-component curable resin is thermally stable and does not melt even in the case where the vicinity of the terminal is likely to be relatively high in normal use, and can reliably suppress thermal expansion and contraction.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the present embodiment.

(Embodiment 1)
1 to 2 are schematic configuration diagrams of a planar heating element according to Embodiment 1 of the present invention, FIG. 1 is a plan view, and FIG. 2 is an XY sectional view in the vicinity of a terminal portion in FIG.

  In FIG. 1, a planar heating element 1 overlaps a pair of electrodes 3 formed by printing and drying a silver paste on a relatively elastic electrically insulating base material 2 such as polyethylene terephthalate and the like. The resistor 4 is formed by printing and drying the resistor ink. And the terminal 5 is bonded on the pair of electrodes 3 as a power feeding part. Further, a thin-walled electrically insulating overcoat such as polyethylene terephthalate is formed in advance with an adhesive resin layer 9 such as a copolyester adhesive having adhesiveness with the electrode 3, the resistor 4, and the electrically insulating substrate 2. It is formed by laminating an electrically insulating covering base material 8 laminated with a coating material.

  The electrode 3 is provided with wide main electrodes 3a and 3b so as to face each other, and a plurality of comb-shaped branch electrodes 3c and 3d are provided alternately from the main electrodes 3a and 3b, and overlap each other. By supplying power to the resistor 4 arranged in this way from the branch electrodes 3c and 3d, a current flows through the resistor 4 to generate heat.

For example, when a polymer resistor having PTC characteristics is used for the resistor 4, the resistance value of the resistor 4 increases as the temperature rises, and has a self-temperature adjusting function so as to reach a predetermined temperature. It has a function as the planar heating element 1 which does not require control and has high safety. Since the sheet heating element 1 having this kind of PTC characteristic generally requires a large inrush current in order to obtain rapid thermal performance, a large current flows through the terminal 5 which is a power feeding unit.

  A conductive resin material 5b is formed on the surface of the terminal 5 that is in contact with the power feeding portion of the electrode 3, and the conductive resin material 5b is thermally adhesive to the electrode 3 and is thermosetting. A conductive paste prepared by dispersing silver powder as a conductivity-imparting material in polyester and adding an appropriate amount of isocyanate as a curing agent is used. The conductive resin material 5b at this stage retains thermoplasticity because it is dried at a low temperature so as not to cause a curing reaction due to isocyanate. If heated to an isocyanate curing reaction temperature or higher and pressurized, the electrode 3 is thermally fused, and the electrode 3 and the terminal 5 are electrically and physically joined by the conductive resin material 5b. It will be. In this case, in particular, if the electrode 3 is made of the same kind of resin and the same kind of metal powder as the conductive resin material 5b, the heat fusion property is extremely good. If heat welding is performed under appropriate management, sufficient heat fusion is achieved. Strength and low contact resistance can be obtained.

  Furthermore, since the terminal 5 is sandwiched between the electrically insulating base material 2 and the electrode 3 and the electrically insulating covering base material 8 and integrated with the adhesive resin layer 9, the terminal 5 and the electrode 3 It is configured to be mechanically fixed between them, and it is possible to realize a highly safe configuration that complies with the Electrical Appliance and Material Safety Law.

  As a method for thermally welding the terminal 5 together with the thermosetting reaction, there are a method of applying heat from the outside to the entire vicinity of the terminal with a hot plate, a method of heating only a highly conductive terminal by induction heating, high frequency welding or the like.

  In addition, the material of the printable electrode 3 can hardly be connected to the solder 6, but the terminal 5 and the electrode 3 can be surface-bonded via the conductive resin material 5 b, and the solder 6 can be connected to the terminal 5. Is possible. And according to the above-mentioned connection method, since the conductive resin material 5b can be formed into a thin surface, the junction resistance value can be made extremely low, so that a large current can flow, and the surface By joining, sufficient strength can be secured.

  Therefore, even if the electrode 3 is formed by printing, which can draw a complicated electrode 3 pattern and is excellent in flexibility, but the solder 6 cannot be connected in many cases, the lead wire is connected by the solder 6 through the terminal 5. 7 is formed, and is extremely excellent in productivity, and at the same time, is an extremely strong joint both electrically and physically, withstands a high current, and has high reliability. Furthermore, it is extremely useful when a large amount of current is required because the power supply voltage is low, or when a heating element having a positive resistance temperature characteristic that requires a large inrush current to obtain rapid thermal performance is used. is there.

  After the electrically insulating covering base material 8 is bonded to the electrically insulating base material 2, the electrically insulating covering base material 8 on the terminal 5 is partially removed by laser heating or the like, and the lead wire 7 is soldered to the terminal 5. Connect by welding.

  A tape 10 having rigidity and incombustibility is pasted as a means for suppressing thermal expansion / shrinkage of the base material on the terminal portion made of the terminal 5, solder 6 and lead wire 7 and at least the surface of the electrically insulating base material 2 in the vicinity thereof. .

Examples of the material of the tape having rigidity and incombustibility include metals such as aluminum and copper. By using a metal foil with high thermal conductivity such as aluminum foil or copper foil, the overheated portion can be soaked and thermally diffused, and the electrically insulating substrate 2 or the electrically insulating coated substrate 9 The effect of suppressing melting and carbonization can be provided at the same time.

  As described in the subject of the present invention, the thermal expansion / shrinkage suppression tape 10 which is a thermal expansion / shrinkage suppression means exhibits an effect when the contact resistance between the terminal 5 and the electrode 3 is greatly increased and is overheated. . That is, when the fine contact portion between the terminal 5 and the electrode 3 is overheated, the electrically insulating base material 2 made of polyethylene terephthalate or the like may be melted and carbonized. At this time, since the temperature of the electrically insulating base material 2 around the fine contact portion of the terminal 5 also becomes high at the same time, the electrically insulating base material 2 contracts, and the contracted electrically insulating base material 2 carbonizes and a new conduction path is formed. The carbonized part expands while forming. Due to a series of cycles of contraction of the electrically insulating base material 2 and expansion of carbonization, there is a problem that the fine contact portion of the terminal 5 continues to be overheated and there is a risk of damaging peripheral members.

  As a result of diligent research, we focused on the mechanism that can suppress the supply of new carbonization material by preventing the shrinkage of the electrically insulating base material 2 by means of thermal expansion and contraction suppression means, and further cut off the carbonized conduction path. It was confirmed that it was possible to use aluminum tape or the like as a means for suppressing thermal expansion and contraction.

  As a result of the experiment, since the electrically insulating base material 2 and the electrically insulating covering base material 8 are carbonized about 1 mm around the terminal 5, the aluminum tape is overheated if pasted so as to cover the shape of the terminal 5 plus 2 mm or more around the periphery. It becomes possible to suppress the persistence of the state.

  Further, as rigidity for suppressing the thermal shrinkage between the electrically insulating base material 2 and the electrically insulating covering base material 8, for example, aluminum tape requires an aluminum thickness of 30 μm or more, and even other materials are rigid. It is necessary to have the same level or higher.

  Furthermore, the thermal expansion / shrinkage suppression tape 10 such as an aluminum tape is similarly applied to the surface of the electrically insulating coated base material 8 to suppress the cycle of melting, shrinking and carbonizing of the electrically insulating coated base material 8 to electrically insulate. It is even better because it can suppress the transfer of carbide to the conductive substrate 2.

  Further, the use of a thin material such as aluminum tape has a feature that the thickness of the terminal portion is substantially the same as that of the conventional planar heating element configuration. This feature is particularly effective when a planar heating element is used in a place where the thickness is limited, such as floor heating, a heater for a vehicle seat, or an electric carpet.

  Furthermore, since the object of the present invention can be provided simply by attaching a tape, it can be manufactured at low cost in terms of material cost and man-hour.

  In the first embodiment, an aluminum tape is assumed as the thermal expansion / shrinkage suppression tape 10. However, the thermal expansion / shrinkage of the electrically insulating base material 2 or the electrically insulating coated base material 8 can be suppressed, and has rigidity and nonflammability. Any substance may be used as long as the object of the present invention is achieved. The same applies to the contents of Embodiments 3 to 5 below.

  In the first embodiment, the shape of the thermal expansion / shrinkage suppression tape 10 covers about 2 mm around the terminal. However, when the amount of current is low or the voltage is low, the possibility of overheating is low, or the electrical When the insulating substrate 2 or the electrically insulating covering substrate 8 is very thin and has a small thermal expansion / contraction force, the shape may be reduced within a range that achieves the object of the present invention. The same applies to the contents of Embodiments 3 to 5 below.

(Embodiment 2)
3 is an XY cross-sectional view in the vicinity of the terminal portion of FIG. 1 in Embodiment 2 of the present invention.

  In FIG. 3, the second embodiment is different from the first embodiment in the thermal expansion / shrinkage suppression means of the electrically insulating base material 2 and the electrically insulating coated base material 8 that cover the vicinity of the terminals 5 and 5. The same parts are given the same numbers and only different parts will be described.

  That is, the electrically insulating resin 11 is used for the thermal expansion / shrinkage suppression means.

  As a material of the electrically insulating resin 11, for example, a thermoplastic hot melt agent, two-component curable urethane, silicone, or epoxy may be used.

  In particular, thermoplastic hot melt agents are generally faster in shape stabilization after application than urethane, silicone and epoxy, and have high production efficiency.

  Naturally, the thermoplastic hot melt agent melts at high temperatures, but its heat capacity and heat of fusion are large, and since the overheating state is completed in a short time, the thermoplastic hot melt agent does not soften or melt and is electrically insulated. There is no concern that the thermal expansion and contraction of the conductive base material 2 cannot be suppressed.

  On the other hand, two-component curable urethanes, silicones, and epoxies have better heat resistance than thermoplastic hot-melt agents, so even in use conditions where the vicinity of the terminal tends to be soft enough to start softening the hot-melt agent. Very useful for keeping solidified.

  For example, when polyethylene terephthalate is used for the insulating base material 2 or the insulating covering material 8, the resin material containing a copolymerizable polyester material can be used as the material of the electric insulating resin 11. 11 and the insulating base material 2 are in a good adhesion state, and the thermal expansion and contraction of the electrically insulating base material 2 is strongly suppressed.

  As for the shape, it covers the shape of the terminal 5 plus the periphery of 2 mm or more, and the thickness direction is 0.3 mm or more, although it depends on the material, in order to maintain the rigidity for suppressing the thermal expansion and contraction of the electrically insulating base material 2 It is.

  In order to maintain the thickness of the electrically insulating resin 11, it is effective to use a mold in which a necessary shape is hollowed out in advance and press the mold until the resin is cured. As a precaution in manufacturing, it is necessary to perform a mold release process on the embossing jig so that the electrically insulating resin 11 does not adhere. The optimum method differs depending on the material of the electrical insulating resin 11 to be used. For example, in the case of a thermoplastic hot melt adhesive, a metal such as aluminum is used, or a silicone or fluorine-based release agent is applied to the embossing surface in advance. By doing so, it is possible to avoid the electrical insulating resin 11 from adhering to the embossing jig, and it is possible to realize a good adhesive state between the electrical insulating resin 11 and the electrical insulating substrate 2.

  In the present embodiment, the processed shape of the electrical insulating resin 11 is such that the periphery of the terminal 5 is covered by about 2 mm. However, when the amount of current is low or when the voltage is low, the possibility of overheating is low, or the electrical insulation is performed. If the thermal expansion / contraction force is small because the conductive substrate 2 or the electrically insulating covering substrate 8 is very thin, the shape may be small and thin as long as the object of the present invention is achieved. The same applies to the contents of Embodiments 3 to 5 below.

(Embodiment 3)
4 is an XY cross-sectional view of the vicinity of the terminal portion of FIG. 1 according to the third embodiment of the present invention.

In FIG. 4, the third embodiment is that the thermal expansion / shrinkage suppression tape 10 is disposed not only on the surface of the electrically insulating substrate 2 but also on the electrically insulating coated substrate 8. The same parts are denoted by the same reference numerals and only different parts will be described. In FIG. 4 (a), as in the first embodiment, the electrically insulating base material 2 uses the thermal expansion / contraction tape 10 as the thermal expansion / contraction suppression means. In FIG. 4 (b), as in the second embodiment, It is the figure which used the electrically insulating resin 11 for the electrically insulating base material 2 as a thermal expansion shrinkage | contraction suppression means.

  Since the thermal expansion / shrinkage suppressing means is also provided on the electrically insulating covering base material 8, the contact resistance between the terminal and the electrode becomes very large, and the electrically insulating covering material 8 is also in an overheated state. There is no contraction. Carbide generated from the electrically insulating coating material 8 will not move to the electrically insulating base material side and form a new conduction path, so that it will not be able to conduct safely without maintaining an overheated state. Can do. Therefore, it is particularly useful when the electrically insulating coating material 8 is thin or easily carbonized by using a resin that is easily carbonized.

  When the thermal expansion and contraction tape 10 is used on the surface of the electrically insulating base material 8, the shape of the terminal 5 is the same as that of the surface of the electrically insulating base material 2. It becomes possible to suppress the persistence of the state.

  Although the overheated state is caused by an increase in contact resistance between the terminal 5 and the electrode 3, since the terminal 5 is a metal incombustible material, the electrically insulating covering base material 8 substantially above the terminal 5 has a thermal expansion / contraction tape 10. May not be attached. That is, it is not necessary to cause the thermal expansion / contraction tape 10 to follow the unevenness caused by the lead wire 7 or the like completely. The electrically insulating covering base material 8 at the terminal 5 is important, and the thermal expansion and contraction tape 10 needs to be adhered to the vicinity of the terminal 5.

  Since a thin material called the thermal expansion and contraction tape 10 is used, the thickness of the terminal portion is characterized by being almost the same as that of the conventional planar heating element configuration. This feature is particularly effective when a planar heating element is used in a place where the thickness is limited, such as floor heating, a heater for a vehicle seat, or an electric carpet.

  Further, when the thermal expansion / contraction tape 10 is sufficiently large so as to cover the lead wire 7 and the solder 6, it is possible to simultaneously perform mechanical fixing of the joint portion with the thermal expansion / contraction tape 10.

  Furthermore, since the object of the present invention can be provided simply by attaching a tape, it can be manufactured at low cost in terms of material cost and man-hour.

(Embodiment 4)
FIG. 5 is an XY cross-sectional view in the vicinity of the terminal portion of FIG. 1 in Embodiment 4 of the present invention. In FIG. 5, the fourth embodiment is different from the first and second embodiments in that the electric insulating resin 11 is disposed not only on the surface of the electric insulating substrate 2 but also on the electric insulating coating substrate 8. Different parts are given the same reference numerals and only different parts will be described. In FIG. 5 (a), as in the first embodiment, the electrically insulating base material 2 uses the thermal expansion / contraction tape 10 as the thermal expansion / contraction suppression means, and in FIG. 5 (b), as in the second embodiment, It is the figure which used the electrically insulating resin 11 for the electrically insulating base material 2 as a thermal expansion shrinkage | contraction suppression means.

  The electric insulating resin 11 has a function of maintaining the electric insulation of the joint portion of the lead wire 7 and a function of fixing the lead wire 7 at the same time. Therefore, although it depends on the material, it needs a thickness of 0.5 mm or more.

  When the electrically insulating resin 11 is used on the surface of the electrically insulating covering base 8, the electrode 3 and the resistor 4 fed by the electrode 3 from the attachment portion of the lead wire 7 are protected by the electrically insulating resin 11, and the outside air By being cut off, it is configured to prevent problems such as contamination deterioration due to moisture and foreign matter, and short-circuiting due to migration of the electrode 3, and the performance stability and durability can be further improved.

  The electrically insulating resin 11 can follow relatively complicated irregularities such as the lead wire 7 mounting portion in a softened state at the time of manufacture, and can be made a predetermined thickness and shape by a simple embossing jig. It is possible to make the production management simple.

  When the electrical insulating resin 11 is applied, the lead wire 7 is pulled out in a direction different from the direction in which a force may be applied to the product, so that even when a force is applied to the product, the terminal 5 Direct force is not applied, and peeling between the terminal 5 and the electrode 3 can be suppressed.

  In particular, by using the thermal expansion / shrinkage suppression tape 10 on the surface of the electrically insulating substrate 2 as shown in FIG. 5A, the surface of the electrically insulating substrate 2 can be kept almost smooth. A heater without unevenness that is easy to use by arranging a smooth surface (surface of the electrically insulating base material 2) on the surface that the user touches when installing a sheet heating element on a vehicle seat heater, electric carpet, etc. Can be provided. Further, for example, when a planar heating element is installed in floor heating, a planar heating element that fits between flooring materials can be obtained by cutting only a part of one side of the flooring material. As described above, if only one side is smooth, the usage can be expanded.

  Furthermore, by using the electrically insulating resin 11 as the means for suppressing thermal expansion / shrinkage on only one surface, the back surface is smooth, so that the embossing performed after the processing of the electrically insulating resin 11 is easy, which can contribute to the improvement of productivity.

  Finally, (Table 1) shows a list of thermal expansion / shrinkage suppression means shown in the first to fourth embodiments so far.

  In any combination included in (Table 1), the contact resistance between the terminal and the electrode, which is the object of the present invention, becomes very large, and the electrical insulating base material is prevented from shrinking when overheated. In addition, it is possible to make it impossible to conduct safely without maintaining the overheating state.

(Embodiment 5)
6 is an XY cross-sectional view in the vicinity of the terminal portion of FIG. 1 according to the fifth embodiment of the present invention.
In FIG. 6, the fifth embodiment is different from the first to fourth embodiments in that in addition to the thermal expansion / shrinkage means, an electrical insulating tape covering the thermal expansion / shrinkage suppression means is provided. Only the different parts will be described.

Any combination shown in Table 1 has an effect and can be applied, but in FIG. 6, the heat insulating shrinkable tape 10 is coated on the surface of the electrically insulating substrate 2 and the electrically insulating tape 12 so as to cover it, which is particularly effective. And an electrically insulating tape 12 is disposed on the surface of the electrically insulating coating material 8 so as to cover the electrically insulating resin 11.

  First, the configuration of the thermal expansion / contraction tape 10 and the electrical insulating tape 12 on the surface of the electrically insulating substrate 2 will be described.

  Generally, as a single material considered as the thermal expansion / shrinkage suppression tape 10 having rigidity and nonflammability, there are many metal materials, and therefore there is no insulation. Originally, the surface of the electrically insulative base material 2 is insulative, but when the electrically insulative base material 2 has voids such as pinholes, or when scratches from the outside are formed, the terminals that are the object of the present invention When there is an overheated state in the vicinity of 5 and the electrically insulating substrate 2 in the vicinity of the terminal portion is melted and carbonized, the insulating property is lost. In this embodiment, the electrical insulating tape 12 has a function of maintaining electrical insulation even in the above case.

  Further, when the combination of the thermal expansion / contraction tape 10 and the electrical insulating tape 12 is used on the surface of the electrical insulating coating material 8, the insulating property is simply given by the electrical insulating tape 12.

  Next, the structure of the electrically insulating resin 11 and the electrically insulating tape 12 on the surface of the electrically insulating coating substrate 8 will be described.

  In order to keep the thickness and shape of the electrically insulating resin 11, it is effective to carry out the embossing until the electrically insulating resin 11 is cured with the embossing tool subjected to the mold release treatment. This has been described in the third embodiment.

  If this embodiment is used, it is possible to finish the embossing when the shape is stabilized to some extent by using the electrically insulating tape 12 between the embossing jig and the electrically insulating resin 11, and the production efficiency is extremely good. Become. In addition, it is not necessary to ensure the mold releasability of the embossing jig, and the manufacturing process and manufacturing management become simple.

  Further, the planar heating element 1 has a thin wall shape, and therefore it is usually overlaid in the manufacturing process. However, since the electrically insulating resin 11 generally has adhesiveness until it is cured, There is a concern that it may adhere to a planar heating element or the like. In the present embodiment, covering the electrical insulating resin 11 with the electrical insulating tape 12 eliminates the concern and extremely improves the production efficiency.

  The effect of covering the electrical insulating resin 11 with these electrical insulating tapes 12 is the same even when used on the surface of the electrical insulating substrate 2.

  In this embodiment, the electrical insulating tape 12 is applied to the thermal expansion / contraction means on both sides of the electrical insulating base material 2 and the electrical insulating coating material 8, but the electrical insulating tape is applied only to one side depending on the use environment and cost. It is also possible to use 12.

  In FIG. 6, the electrical insulating tape 12 is indicated as a separate member by the electrical insulating base material 2 and the electrical insulating coating material 8, but the electrical insulating base material 2 and the electrical insulating coating material are formed by a single member. By covering the thermal expansion / contraction means on both sides of the 8, it is possible to contribute to productivity improvement.

  In the first to fifth embodiments, the bonding between the terminal 5 and the electrode is assumed to be a conductive resin material of a thermosetting resin. However, if the terminal 5 is used and the object of the present invention is achieved, its configuration Any material may be used. For example, a method such as caulking or spot welding may be used for joining the terminal 5 and the electrode 3, or an ultraviolet effect resin, a two-liquid effect resin, a moisture curable resin, or the like may be used as the conductive resin material. good.

  In the first to fifth embodiments, polyethylene terephthalate is assumed for the insulating base material 2 and the insulating covering material 8, but the range in which the object of the present invention is achieved with a substance that shrinks, melts and carbonizes by overheating. Any other material may be used.

  As described above, in the planar heating element according to the present invention, the adhesion state between the electrode and the terminal cannot be ensured by long-term use, and it is simple and low-cost to be in a non-conductive state safely even when the contact resistance increases. For example, it is useful as a heating element installed in a facility heating product that is installed in a house such as floor heating or wall heating and used for a long time.

Schematic diagram of planar heating element in Embodiments 1 to 5 XY cross-sectional schematic diagram of the terminal part vicinity of FIG. 1 in Embodiment 1. FIG. XY cross-sectional schematic diagram of the terminal part vicinity of FIG. 1 in Embodiment 2. FIG. (A) XY cross-sectional schematic diagram in the vicinity of the terminal portion in FIG. 1 when the thermal expansion and contraction tape is used on the surface of the electrically insulating substrate in the third embodiment (b) The electrically insulating substrate in the third embodiment XY cross-sectional schematic diagram of the vicinity of the terminal portion of FIG. 1 when an electrically insulating resin is used for the surface (A) XY cross-sectional schematic diagram in the vicinity of the terminal portion of FIG. 1 when the thermal expansion and contraction tape is used on the surface of the electrically insulating substrate in the fourth embodiment (b) The electrically insulating substrate in the fourth embodiment XY cross-sectional schematic diagram of the vicinity of the terminal portion of FIG. 1 when an electrically insulating resin is used for the surface XY cross-sectional schematic diagram of the terminal part vicinity of FIG. 1 in Embodiment 5. FIG. (A) Plan view showing the configuration of a conventional heating element (b) Cross-sectional view of the heating element terminal portion

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Planar heating element 2 Insulating base material 3 Electrode 4 Resistor 5 Terminal 6 Solder 7 Lead wire 8 Electrically insulating covering base material 9 Adhesive resin layer 10 Thermal expansion shrinkage suppression tape 11 Electrical insulating resin 12 Electrical insulating tape

Claims (8)

An electrically insulating base material made of a resin material such as polyethylene terephthalate; a lead wire for supplying power; a pair of electrodes disposed on the electrically insulating base material; and an electrical connection between the electrode and the lead wire. A surface comprising a terminal for performing mechanical bonding, and a resistor that generates heat by applying a voltage by the electrode, and includes an electrically insulating covering base material that covers at least the terminal and is bonded to the electrically insulating base material In the sheet heating element, a sheet heating element provided with thermal expansion / shrinkage suppression means on the side of the sheet heating element on the side of the sheet insulating element covering the terminal and the vicinity of the terminal. The surface according to claim 1, further comprising means for suppressing thermal expansion and contraction of the electrically insulating coating material on the side of the electrically insulating coating material of the planar heating element in addition to the means for suppressing thermal expansion and contraction on the side of the electrically insulating substrate. Heating element. The planar heating element according to claim 1 or 2, further comprising an electrically insulating tape that covers the thermal expansion / shrinkage suppression means in at least one thermal expansion / shrinkage suppression means. The sheet heating element according to any one of claims 1 to 3, wherein the thermal expansion / shrinkage suppression means is a thermal expansion / shrinkage suppression tape having rigidity and incombustibility. The sheet heating element according to any one of claims 1 to 3, wherein the thermal expansion / shrinkage suppression means is formed of an electrically insulating resin. The sheet heating element according to claim 4, wherein the thermal expansion / shrinkage suppression tape comprises a tape base material having a high thermal conductivity and an adhesive material. The sheet heating element according to claim 5, wherein the electrically insulating resin is a thermoplastic hot melt adhesive. The planar heating element according to claim 5, wherein the electrically insulating resin is a two-component curable resin.