JP3484927B2 - Planar heating element - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an electrode such as a planar heating element. More specifically, the present invention relates to a planar heating element having an electrode that has durability even under use conditions with a large temperature difference.

[0002]

2. Description of the Related Art As a prior art relating to the present invention, there are sheet heating elements shown in FIGS. FIG. 9 is a plan view showing the interior of a defogging mirror device in which the sheet heating element 50 is attached to the back surface of the mirror body 60, with the inside cut away.
10 is a sectional view taken along the line AA of FIG.

In FIGS. 9 and 10, the mirror body 60 is shown.
The planar heat generating element 50 via the thermally conductive adhesive 51 on the back of the
The insulating sheet 52 provided in the above is adhered.

The sheet heating element 50 further has a heating element 53 bonded to the surface of the insulating sheet 52. Furthermore, on the surface of the heat generating element 53, a first electrode layer 54A and a second electrode layer 54B of copper foil, which are bonded by thermocompression bonding, are formed.

Further, a film-shaped insulating sheet 55 made of a polyester material is provided on the outer surface of the electrode layer 54 so as to cover each electrode layer 54 and the heating element 53. The above-mentioned insulating sheet 52, the heating element 53 adhered to the insulating sheet 52, the electrode layer 54 integrated with the heating element 53, and the insulating sheet 55 on the outer side constitute the planar heating element 50. .

The sheet heating element 50 is further covered from the outer peripheral surface with a metal sheet 56 of an aluminum foil film, and is sandwiched between the sheet and the mirror body 60.

The sheet heating element 50 is constructed so as to have flexibility as a whole. Further, a first connection terminal 57A and a second connection terminal 57B, which are attached to the outer surface of the metal sheet 56 and are connected to the internal electrode layer 54, are provided. Further, each connection terminal 57A, 57B has a first lead wire 58A and a second lead wire 58 for connecting to a power source.
It is connected to B.

[0008]

The sheet heating element 50 of this conventional example is constructed as described above, is disposed in the mirror body 60, and is installed in a vehicle or the like as a defrosting device for the mirror. The sheet heating element 50 is mounted on a vehicle and is utilized in cold regions, and rapid heat generation and cooling are repeated.

When the heat generation and the cooling are repeated in this manner, the conventional copper foil electrode layer 54 is bonded to the heating element 53 and the insulating sheet 52, and at the same time constitutes the heating element 53 and the insulating sheet 52. Since the linear expansion coefficient is different from that of the resin material, the electrode layer 54 becomes fatigued and cracked. As a result, the electricity supply to the electrode layer 54 becomes poor, which causes a reduction in heat generation of the planar heating element 50.

[0010] In particular, the expansion and contraction are repeated in the electrode layer 54, electrode layer 54, in order to entirely uniform heating, cracks in the corners P of comb shape formed branch electrodes 6 2 base Will occur. The main electrode 61 is a branch electrode 62.
Since the expansion and contraction of the main electrode 61 is restricted by the above, the main electrode 61 is cracked.

The present invention has been made in view of the above-mentioned problems, and its technical problem is to use it as an electrode of a sheet heating element or the like in a cold region or a low temperature device. When it is used for other purposes, cracks are prevented from occurring even if the electrode expands or contracts.

Another object is to improve durability without causing cracks even when the sheet heating element or the printed circuit board is energized intermittently.

[0013]

The present invention has been made to solve the above-mentioned technical problem, and the technical means is configured as follows. That is, the first aspect of the present invention is a planar heating element that is attached to a mounting member and adjusts heat generation, and includes an electrode 5 that is energized, a heating element 13 that is bonded to the electrode 5 and generates heat between the electrodes 5, and a heating element. The insulating sheet 12 is attached to the element 13 or the electrode 5 to insulate it from the outside, and the electrode 5 has an elongation of 6% to 36% .
Yes, the extensibility is almost the same as that of the heating element 13 and the insulating sheet 12.
It is the same.

A second aspect of the present invention is the sheet heating element according to the first aspect, wherein the bonding surface of the electrode 5 is roughened and is made of electrolytic copper foil. Further, claim 3 is the electrode 5
Is planar heating element according to claim 1, connection angle of the comb shape are formed main electrode 6 and the finger electrode 7 by the main electrode 6 and the finger electrode 7 is formed in a circular arc shape.

[0015]

In the sheet heating element of the present invention, the electrode 5 is the insulating sheet 1.
2 and the heating element 13 are bonded to each other and expand and contract with the insulating sheet 12 and the heating element 13 as the temperature changes. However, since the electrode 5 is made of a material having a high elongation rate, it can expand and contract with the heating element 13 and the insulating sheet 12, and the electrode 5 is prevented from being broken by the heating element 13 and the insulating sheet 12. Therefore, the electrode 5 can be effectively prevented from being damaged or cracked regardless of the tensile strength. Further, even when the sheet heating element 1 expands and contracts with the mounting member (mirror body) 20 to be mounted, the electrode 5 has a large elongation rate, so that the electrode 5 can cope with the expansion with the mounting member 20 and cracks occur. Can also be prevented.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a perspective view of a sheet heating element showing an embodiment according to the present invention. In addition, FIG. 2 shows I-I of FIG.
FIG. Furthermore, FIG. 3 is a perspective view of the insulating sheet 12 in which the electrodes of FIG.

A description will be given below with reference to FIGS. 1, 2 and 3. In FIGS. 1 and 2, reference numeral 1 is a planar heating element. The sheet heating element 1 has therein a heating element 13 made of a conductive polymer material. Then, this heating element 13
Is a pair of first electrodes 5A formed in a comb shape shown in FIG.
A first insulating sheet 12 having an electrode 5 formed on the surface thereof and a second electrode 5B, and a second insulating sheet 15 having a dummy electrode 9 having the same shape as the electrode 5 formed on the surface. It is formed so as to be sandwiched from both sides.

The sheet heating element 1 further includes a pair of first
A first connecting terminal 17A and a second connecting terminal 17B are connected to one ends of the electrode 5A and the second electrode 5B by a first caulking terminal 19A and a second caulking terminal 19B (not shown). The connection terminals 17A and 17B have a first lead wire 18A and a second lead wire 18A.
The lead wire 18B (see FIG. 6) is connected to the electrode 5A,
5B can be energized.

The above-mentioned planar heating element 13 is made of a conductive polymer material by mixing conductive particles and oxide particles with the basic material and kneading them.

As the base material, ethylene vinyl acetate copolymer, ethylene acrylate copolymer, polyolefin, ethylene propylene genter polymer,
A polymer material such as acrylic resin is adopted. The acrylic resin is not particularly limited as long as it is obtained by polymerizing acrylic acid and its derivative. Among them, ethylene acrylic acid copolymer (EAA) is preferred.

As the conductive particles contained in the base material, most of them can be used as long as they have conductivity, but carbon particles such as carbon black, carbon graphite and graphite are preferable. There is. The particle size of the conductive particles is 30 to 300 n.
The range of m is preferable. Further, the volume ratio contained in the base material is preferably in the range of 5 to 50%.

Further, the oxide particles are not particularly limited, but titanium oxide, iron oxide, zinc oxide, silicon oxide and the like are preferably used.

A conductive polymer material liquid obtained by dissolving or decomposing a conductive polymer material having such a composition in an appropriate solvent such as xylene is used as the first insulating sheet 12, the second insulating sheet 15, and each electrode. 5A, 5B on the upper surface, for example, 5
It is formed by coating or printing to a thickness of 0 to 300 μm.

Since the planar heating element 13 made of a conductive polymer material has flexibility, it does not easily crack. If the strength is low, a base cloth such as a specific woven cloth or non-woven cloth can be embedded and reinforced. still,
The inclusion of carbon particles is considered to have a carbon structure and constitute a reinforcing action.

Next, as shown in FIG. 3, the electrode 5 faces the first electrode 5A and the second electrode 5B, which are pattern-formed in a comb shape on the surface of the first insulating sheet 12 made of polyester or the like. Are combined in pairs. Each of these electrodes 5A,
5B is formed of main electrodes 6A and 6B arranged in parallel with each other and branch electrodes 7A and 7B alternately combined. The pattern of each of the electrodes 5A and 5B shows one embodiment, and from the combination of only the main electrodes 6A and 6B substantially in parallel, the pattern of the pattern including the main electrode 6 and the branch electrode 7 shown in FIG. It has been recognized that various patterns can be carried out to exhibit an effective ability up to a complicated one in which each electrode 5 is combined in two rows and three rows. Further, in the present embodiment, GTS-MP Class 3 manufactured by Furukawa Circuit Foil Co., Ltd. is used as the material of each electrode 5A, 5B.

Next, the second insulating sheet 1 made of polyester
The dummy electrodes 9 formed in 5 are also formed in the same shape and thickness as the first electrode 5A and the second electrode 5B, are made of the same material, and are arranged in the same symmetrical position, and warp (bending deformation).
It is used to prevent The dummy electrode 9 does not necessarily need to be energized, but may be energized in order to prevent warping and curling.

Further, the electrodes 5A and 5B have the first and second electrodes, respectively.
Is an electrolytic copper foil whose surface is roughened so that the bonding surface to be bonded to the insulating sheets 12 and 15 and the planar heating element 13 is reduced in surface roughness to increase adhesive strength. The electrolytic copper foil preferably has an elongation rate in the range of 4% to 37% at normal temperature. More preferably, the elongation percentage is 6% to 36%. In addition, each electrode 5A, corresponding to the expansion and contraction of the first and second insulating sheets 12 and 15 and the planar heating element 13,
In order to prevent the crack of 5B, it is preferable that the elongation is adjusted to be substantially the same as the elongation of the polymer material of each of the insulating sheets 12 and 15 and the planar heating element 13. Even if it is not possible to adapt, it is preferable to configure the elongation of each electrode 5A, 5B to be 6% or more. The elongation of the planar heating element 13 is
It is about 4% to 23%, although it varies depending on the blending ratio of the conductive particles and the oxide particles.

As the first electrode 5A and the second electrode 5B, MP grade products manufactured by Furukawa Circuit Foil Co., Ltd. (the surface roughness of the copper foil is reduced to increase the adhesive strength and increase the elongation rate) It was adopted) and good results were obtained. Further, the surface of the roughened electrolytic copper foil may be coated with zinc or nickel. The main electrode 6A is replaced by the branch electrode 7
The corner portion P connected to A has a radius of R = 0.8 mm. If the radius R of this circular arc is in the range of 0.3 mm to 6 mm, cracking from this portion can be prevented.

Although the planar heating element 13 is formed on the surface of each of the insulating sheets 12 and 15 in the above description, the electrodes 5A and 5B may be bonded and formed on both surfaces of the planar heating element 13. .

A method of manufacturing the electrodes 5A and 5B and the heating element 13 will be described below as an example. That is, separately from the kneading step, an electrolytic copper foil whose surface is roughened so that the bonding area is wide is prepared in another step. The electrolytic copper foil is not particularly limited, but an MP grade product having an elongation of 4% or more, for example, manufactured by Furukawa Circuit Foil Co., Ltd. is used. It is preferable to apply zinc coating and nickel coating to the surface of the roughened electrolytic copper foil.

Next, the kneaded material which becomes the planar heating element 13 is dispensed to obtain a sheet-shaped planar heating element material. The sheet thickness is, for example, about 0.3 mm. The roughened electrolytic copper foil is thermocompression bonded to the front and back surfaces of the sheet-shaped heating element material. At that time, the roughened surface of the electrolytic copper foil is pressure-bonded to the heating element material.

This thermocompression bonding step has a function of pressing the electrolytic copper foil and the heating element material so that they do not come off, and heating the material after kneading causes the carbon particles, which are conductive particles, to agglomerate to a predetermined value. It has the function of expressing a resistance value. As the thermocompression bonding conditions, for example, the heating temperature is 170 to 19
The pressure is 0 ° C. and the pressure is about 200 kg / cm ² . By this pressure bonding, the planar heating element 13 having a thickness of 0.3 mm can be obtained.

Warping and curling of the planar heating element do not occur during the heating and pressing step and the subsequent cooling step or etching step because the electrolytic copper foil is heated and pressed on both sides of the heating element. By changing the heating temperature at the time of thermocompression bonding, a planar heating element having an arbitrary resistance value can be obtained. After the thermocompression bonding, the copper foils thermocompression bonded to both surfaces of the planar heating element 13 are etched into a pattern shown in FIG. Even during this etching, the planar heating element 1
It is recognized that no warp or curl is generated in 3.

Then, as shown in FIG. 5, each electrode 5A,
The insulating sheets 12 and 15 are bonded to both surfaces of the planar heating element 13 on which 5B is formed via a room temperature pressure-bonding type silicone adhesive. At that time, as shown in FIG. 2, each caulking terminal 19 is penetrated through the planar heating element 13 at the position of the electrode caulking portion 21, and the tip portion of the caulking terminal 19 is a caulking female terminal. It is connected to the connection terminal 17.

The above-mentioned drawings of the sheet heating element 1 are written for the sake of easy understanding of the description, and there are also points that they are enlarged in a model manner. Then, the outer shape of the sheet heating element 1 is used, for example, by forming the outer shape of the sheet heating element 1 in conformity with a mirror for an automobile and adhering it to the back surface. In addition, each insulation sheet 1
What is used as a preferable material of 2, 15 is, for example, a polymer material such as polyester, polyphenylene sulfide or polyimide.

FIG. 4 is a sectional view of the sheet heating element 1 showing a second embodiment of the present invention. Further, FIG. 5 is a perspective view in which the insulating sheet 12 before assembly of the planar heating element of FIG. 4 is developed.

4 and 5, the electrodes 5A and 5B of the sheet heating element 1 are formed only on the surface of the first insulating sheet 12, and the second insulating sheet 15 has dummy electrodes. This is an embodiment in which 9 is not provided.

The electrodes 5A and 5B are the comb-teeth-shaped first electrode 5A and the second electrode 5 formed in substantially the same manner as shown in FIG.
B and B are formed so as to mesh with each other. And the manufacturing method of this electrode 5A, 5B is made as follows.
That is, an electrolytic copper foil having an elongation rate of about 8% for forming an electrode is bonded to the surface of a polyimide film-shaped first insulating sheet 12 having an elongation rate of about 8% at room temperature with an adhesive, and then an etching process or an electrode is performed. It is formed by joining the patterns. This etching process can be performed by screen printing or exposure printing.

Next, by applying the conductive polymer material liquid on the upper surface of the first insulating sheet 12 on which the electrodes 5A and 5B are formed, the characteristic that the temperature coefficient of the electric resistance is positive, that is, the so-called temperature rise is obtained. Accordingly, the heat generating element 13 made of a conductive polymer material having a heat generating function and having a characteristic that the electric resistance increases and the electric resistance decreases as the temperature decreases (PTC characteristic) is formed. The elongation rate of the heating element 13 is also about 8%.

Further, a first connecting terminal 17A and a second connecting terminal 17B are attached to each of the electrodes 5A and 5B. This attachment is performed after inserting the spring pin-shaped first crimping terminal 19A and the second crimping terminal 19B into the through holes of the heating element 13, the electrodes 5A and 5B, and the insulating sheet 12,
The caulked terminals 19A and 19B are caulked at the end portions of the caulked terminals to crimp each member that has been penetrated.

Further, another insulating sheet 15 functioning as an insulating material is bonded to the surface of the planar heating element 13 by silicon adhesive, and the surfaces of the outer peripheral edges of both insulating sheets are bent and bonded. To do.

The sheet heating element 1 manufactured as described above.
Shows a cross section as shown in FIG. The planar heating element 13 exhibits the function of having a PTC characteristic as an effective heating section between the electrodes 5A and 5B. At the same time, since the elongation rates of the electrodes 5A and 5B are substantially the same as the elongation rates of the planar heating element 13 and the insulating sheet 12 on both sides, the electrodes are damaged even when subjected to repeated expansion and contraction. Can be prevented.

FIG. 6 is a partially cutaway plan view showing a third embodiment of the present invention. 7 is a sectional view taken along the line II-II of FIG.

In FIGS. 6 and 7, the sheet heating element 1 using the electrodes 5A and 5B having an elongation of about 12% at room temperature is used.
Is a mirror body (mounting member) 2 of the exterior of an automobile door
It is formed according to 0. The configuration of the sheet heating element 1 is the same as that of the second embodiment except that the electrodes 5A and 5B are attached to the sheet heating element 13. Then, the planar heating element 1 is bonded to the back surface of the mirror body 20 via the heat conductive adhesive layer 11. The outer surface of the door opposite to the mirror body 20 is covered with a metal foil 16 such as an aluminum foil or a stainless steel foil which is adhered to the insulating sheet 15 to cover the entire surface.

In the case of this door mirror, it is used in a cold region together with an automobile. Therefore, the sheet heating element 1
Will also be exposed to temperatures of -50 ° C. Further, since the electrodes 5A and 5B included in the sheet heating element 1 are different from the expansion rate of the mirror body 20 of the door, only the sheet heating element 1 expands and contracts. The shape is such that the elongation rate on the sheet 12 side has decreased. However, since each of the electrodes 5A and 5B has a large elongation rate with respect to temperature, it is possible to expand and contract in response to this change, so that cracks and damage are prevented.

FIG. 8 shows each electrode 5 formed on the insulating sheet 12 of the sheet heating element 1 according to the fourth embodiment of the present invention.
It is a perspective view which shows A, 5B, 5C, and 5D.

In FIG. 8, each electrode 5A, 5B, 5C, 5
For D, an electrolytic copper foil having a large elongation at room temperature of 23% is used. And each 1st electrode 5A and 2nd electrode 5
B, the third electrode 5C, and the fourth electrode 5D are arranged on the upper surface of the first insulating sheet 12 so that the main electrodes 6A, 6B, 6C, and 6D are parallel to each other. Furthermore, each branch electrode 7A, 7B, 7
C and 7D are also combined so as to form a gap and mesh with each other.

The main electrodes 6A, 6B, 6C, 6D of the respective electrodes 5A, 5B, 5C, 5D and the branch electrodes 7A, 7B, 7C,
The corner portion P intersecting with 7D is preferably formed entirely or at a portion where the temperature is high and low in an arc shape having a radius R of 0.3 mm or more. A preferable example of this radius R is R
= 0.3 mm to 6 mm.

In the sheet heating element 1 of the fourth embodiment, the main electrodes 6A, 6B, 6C and 6D are heated in order to heat the entire surface uniformly.
And a plurality of branch electrodes 7A, 7B, 7C, 7D. Therefore, in a cold region, the temperature change may be large between the inside and the outside of the sheet heating element 1. However, since the electrodes 5A, 5B, 5C, and 5D have a high elongation rate of 23% with respect to high temperature, they can cope with high and low temperatures and can effectively prevent cracks from occurring.

In particular, since the arcuate R surface is attached to the corner P of the root of the branch electrodes 7A, 7B, 7C, 7D with the main electrodes 6A, 6B, 6C, 6D, cracks are generated from this portion. Can also be prevented.

As described above, there are various materials used as the electrodes of the sheet heating element of the present invention. Among them, as electrolytic copper foil, HD-TYPE E (Furukawa Circuit Foil Co., Ltd. product name GTS-MP), which has a high elongation at room temperature classified by IPC standard, and HTE-T, which has a high elongation at high temperature, are also used.
YPE E (Same company's product GTS-MP) and ANN-
TYPE E, which is an annealed foil with high high temperature elongation, has been found to be suitable.

In particular, the IP of the product name GTS-MP foil mentioned above.
Class 1 of C classification has a foil thickness of 35 μ at room temperature, a tensile strength of 29 kg / mm ² , and an elongation of 23%. Even at a high temperature of 180 ° C, the elongation is 13% at a tension of 17 kg / mm ² . Furthermore, in the GTS-MP foil of IPC classification 2 and 3, the tensile strength at room temperature is 28 kg / mm.
^The elongation is 36% at ² , and the elongation is 11% at a tensile strength of 18 kg / mm ² even at a high temperature of 180 ° C. It is recognized that these electrolytic copper foils exhibit excellent durability as electrodes. In particular, it has excellent followability with respect to thermal expansion and contraction of the heating element 13 and the insulating sheet 12.

It is also recognized that the surface treatment roughness of the electrode 5 is proportional to the peeling strength of the electrode 5. Therefore, generation of cracks can be prevented by reducing the surface roughness of the electrode 5.

[0055]

EFFECTS OF THE INVENTION The sheet heating element of the present invention is used in cold regions and the like because the electrode is made of a material having a large elongation at room temperature and high temperature. ,
Even if a tensile force is applied from the insulating sheet due to an external force, the tensile force corresponds to this external force, so that damage can be prevented.

Further, a large number of branch electrodes are formed in order to make the temperature distribution of the heating elements of the planar heating element uniform, but the more branches, the more complicated tension acts on the electrodes. But,
Since the electrode is composed of a material with a high elongation rate,
It is possible to extend corresponding to this tension, and it is possible to effectively prevent damage from occurring due to the tension. Therefore, it is possible to design an electrode having a complicated branch electrode, and it is possible to make the temperature distribution over the entire surface of the planar heating element uniform.

Furthermore, by forming the corners of the electrodes, where the main electrodes and the branch electrodes are connected, in an arc shape, the damage such as cracks occurs near the corners in cooperation with the expansion rate of the electrodes. Can be expected to be effectively prevented. Further, since the surface roughness of the bonding surface of the electrode is made small, it is recognized that the bonding strength between the insulating sheet and the heating element is improved by 25% as compared with the conventional one, and the effect of preventing electrode damage is recognized. .

[Brief description of drawings]

FIG. 1 is a perspective view of a sheet heating element showing an embodiment according to the present invention.

2 is a cross-sectional view taken along the line II of FIG.

3 is a perspective view showing a state in which the insulating sheet having the electrodes of FIG. 2 attached thereto is spread on a plane. FIG.

FIG. 4 is a sectional view of a sheet heating element showing a second embodiment according to the present invention.

FIG. 5 is a perspective view showing a state where the insulating sheet having the electrodes of FIG. 4 attached thereto is spread on a plane.

FIG. 6 is a plan view in which a portion showing a third embodiment according to the present invention is broken away.

7 is a cross-sectional view taken along the line II-II of the sheet heating element of FIG.

FIG. 8 is a perspective view of an insulating sheet to which an electrode is bonded according to a fourth embodiment of the present invention.

FIG. 9 is a plan view in which a portion of a conventional sheet heating element is broken away.

10 is a cross-sectional view taken along the line AA of FIG.

[Explanation of symbols]

1 ... Sheet heating element 5 electrode 5A 1st electrode 5B 2nd electrode 5C 3rd electrode 5D 4th electrode 6A ... First main electrode 6B ... Second main electrode 6C 3rd main electrode 6D 4th main electrode 7A ... First branch electrode 7B ... Second branch electrode 7C ... 3rd branch electrode 7D: Fourth branch electrode 9 ... Dummy electrode 11 ... Adhesive 12: First insulating sheet 13 Heating element 15 Second insulation sheet 16 ... Metal foil 17A ... First connection terminal 17B ... Second connection terminal 18A ... 1st lead wire 18B ... Second lead wire 19A ... 1st crimp terminal 19B: Second crimp terminal 20: Mirror body 21 ... Electrode caulking part 50: Sheet heating element 51 ... Adhesive 52 ... Insulation sheet 53 ... Heating element 54A ... first electrode layer 54B ... Second electrode layer 55 ... Insulation sheet 56 ... Metal sheet 57A ... First connection terminal 57B ... Second connection terminal 58A First lead wire 58B ... Second lead wire 60: Mirror body 61 ... Main electrode 62 ... Branch electrode P ... Corner

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Claims (3)

(57) [Claims] 1. A planar heating element mounted on a mounting member for adjusting heat generation, wherein heat is generated between an electrode (5) to be energized and the electrode (5) by being bonded to the electrode (5). It has an element (13) and an insulating sheet (12) that is adhered to the heating element (13) or the electrode (5) and insulates it from the outside, and the electrode (5) has an elongation of 6% to 36%. % And before
Along with the heating element (13) and the insulating sheet (12)
A sheet heating element having substantially the same rate . 2. The electrode (5) is the heating element (13).
Or said insulating sheet (12) and the planar heating element according to 請 Motomeko first joint surface has been configured by electrolytic copper foil with is roughened. 3. The electrode (5) is formed in a comb shape by a main electrode (6) and a branch electrode (7), and a connection angle between the main electrode (6) and the branch electrode (7). sheet heating element according to 請 Motomeko 1 or 2 parts (P) are formed in an arc shape.