JP2001319760A - Heater substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heater substrate in which an electrode retaining part can be aimed at being thin layered and in which the electrode flaking off by heat can be prevented as well. SOLUTION: This is the heater substrate 8 to be characterized by that after an electrode pattern 1 composed of noble metal is printed and baked on a crystallized glass 7, an electro-conductive heat generating body 2 is printed and baked so as to coat at least a part of it.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

2. Description of the Related Art As a heater substrate, as shown in FIGS. 4 to 6, a conductive heating element 92 is coated on a ceramic heat-resistant insulating substrate 97, and electrode thin plates 93 are provided at both ends of the conductive heating element 92. There is something. As shown in FIGS. 5 and 6, a terminal member 9 is provided between the conductive heating element 92 and the electrode thin plate 93.
4 is attached. In FIG. 6, reference numerals 941 and 94
2 is a connection hole and a wiring mounting hole. Heat resistant insulating substrate 9
7 receives heat from the conductive heating element 92 and emits far-infrared rays to raise the temperature of the surrounding environment.

[0002]

However, in the above-described conventional heater substrate, the electrode thin plate 93 may be distorted by heat. Therefore, it is conceivable to attach a porous foamed metal to the surface of the electrode thin plate 93 to prevent thermal distortion by its own weight (Japanese Utility Model Publication No. 5-18872).

However, the terminal member 94 is connected to the conductive heating element 92.
And the electrode thin plate 93, and further mounting a porous foamed metal thereon, the electrode holding portion becomes considerably thick. In addition, when repeatedly heated, the thin electrode plate 93 is peeled off due to the difference in thermal expansion between the heat-resistant insulating substrate 97 and the conductive heating element 92. This peeling is caused by the electrode thin plate 93.
Is more likely to occur as the thickness increases. The peeling of the electrode plate
If it occurs once in the whole, the energization is stopped as soon as it occurs, but if the film is peeled off little by little by the repetition of the thermal cycle, current concentration occurs. For this reason, a heat spot is generated in the conductive heating element, causing a sudden rise in partial temperature.
Melting or cracking occurs.

The present invention has been made in view of the above-mentioned conventional problems, and has as its object to provide a heater substrate capable of reducing the thickness of an electrode holding portion and preventing the electrode from peeling off due to heat.

[0005]

A first aspect of the present invention is to print and bake an electrode pattern made of a noble metal on crystallized glass, and then print and bake a conductive heating element so as to cover at least a part of the electrode pattern. A heater substrate characterized by the following.

The most characteristic feature of the present invention is that an electrode pattern is formed by printing, a conductive heating element is printed thereon, and these are baked. Since both the electrode pattern and the conductive heating element are formed by printing, the thickness can be made extremely thin as compared with the related art. For this reason, even if heating is repeated, peeling of the electrode pattern due to the difference in thermal expansion between the crystallized glass and the electrode pattern hardly occurs. Also, crystallized glass having high thermal shock strength is used as the far-infrared radiation substrate. Therefore, the heat resistance of the heater substrate is further increased.

The noble metal is used for the electrode pattern.
This is because the conductivity is high and the electrode characteristics are satisfied. As in the invention of claim 2, the noble metal constituting the electrode pattern is
It is preferable to be composed of one or more of silver, palladium and gold. As a result, the electric resistance becomes extremely low, and the heat generation of the electrode pattern can be suppressed, and distortion and peeling due to heat can be prevented.

According to a third aspect of the present invention, the electrode pattern has a terminal portion having the same width as the width of the conductive heating element, and the terminal portion is preferably covered with the conductive heating element. . Since the terminal portion has a lower electrical resistance than the conductive heating element, electricity flows over the entire width of the terminal portion and then flows almost simultaneously into the entire width of the conductive heating element. Thus, the current flows uniformly throughout the conductive heating element. Therefore, a partial heat spot does not occur, and the entire conductive heating element generates heat uniformly. Therefore, heat having a uniform temperature distribution is transmitted to the crystallized glass, and far infrared rays can be uniformly radiated from the whole. Further, since no heat spot is generated, it is possible to prevent a defect such as partial cracking of the conductive heating element.

It is preferable that the terminal portion protrudes from the center of the terminal portion. This allows a current to flow uniformly through the terminal portion to the entire conductive heating element.

The terminal portion is exposed from the conductive heating element. The terminal section is where the wiring is attached. Although only one terminal portion may be provided for one electrode pattern, two or more terminal portions may be provided. With two or more, electricity can be distributed quickly and over a wide area, and heat can be efficiently generated.

The conductive heating element is carbon; SnO ₂ , I
Semiconductor metal oxides, such as _{n-SnO 2; Ag, Cu} ,
A metal resistor such as Ag-Pd can be used. It is preferable that the conductive heating element is made of carbon. This gives
Inexpensive and easy to print and print on a large area.

As the crystallized glass, known ones can be used, but low expansion crystallized glass is preferable. Thereby, the thermal shock resistance is further improved. As the low expansion crystallized glass, for example, Li ₂ O—Al ₂ O
There are ₃ -SiO ₂ based glass. As crystallized glass,
_{MgO-Al 2} O 3 -SiO _{2 system,} Li 2 O-CaO-
An SiO ₂ type or the like can be used.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment A heater substrate according to an embodiment of the present invention will be described with reference to FIGS.
This will be described with reference to FIG. As shown in FIGS. 1 and 2, the heater substrate 8 of the present embodiment prints and prints the electrode pattern 1 made of a noble metal on the crystallized glass 7 and then conducts the conductive heat so as to cover a part of the electrode pattern 1. The body 2 is printed and printed.

As shown in FIG. 1, the electrode pattern 1 includes a terminal portion 11 having the same width as the conductive heating element 2 and a terminal portion 12 projecting from the center of the terminal portion 11, and has an overall shape. It is T-shaped. As shown in FIG.
The terminal 11 is covered with the conductive heating element 2, while the terminal section 12 is exposed from the conductive heating element 2.
The conductive heating element 2 is made of carbon and has a resistance value of 18.
5Ω, thickness is 200 μm.

The crystallized glass 7 is a low expansion crystallized glass having a plate shape of 300 × 400 × 3 mm, a coefficient of thermal expansion of 8 × 10 ⁻⁷ / ° C., a thermal shock strength of 600 ° C.
The maximum safe operating temperature is 800 ° C for continuous heating, 900 ° C for short-term heating, and the specific heat is 800 J / kg ° C.
The thermal conductivity is 1.7.

As shown in FIG. 2 and FIG.
When the wiring 5 is soldered to the terminal portion 12 and an electric current flows, the conductive heating element 2 generates heat. This heat is transmitted to the crystallized glass 7 and radiates far infrared rays 6. Thereby, the temperature of the surrounding environment of the heater substrate 8 is increased.

Next, a method for manufacturing the heater substrate of the present embodiment will be described. A noble metal paste containing Ag is pattern-printed on both ends of the crystallized glass 7 by a screen printing method. The printing pattern has a T-shape, and includes a terminal portion extending in the width direction of the conductive heating element forming portion, and a terminal portion projecting outward from the terminal portion. The print position is
Both ends of the portion where the conductive heating element is formed are arranged symmetrically with respect to the portion where the conductive heating element is formed. Next, baking is performed at a high temperature in a firing furnace to form a pair of electrode patterns.

Next, a pattern of carbon paste is printed by a screen printing method between the pair of electrode patterns. At this time, the terminal portion of the electrode pattern is covered with the carbon paste. Next, these are baked in a firing furnace to form a conductive heating element 2. As shown in FIG. 3, the wiring 5 is soldered to the terminal portion 12 of the electrode pattern 1.

The heater substrate of this example was subjected to a continuous conduction test (AC 100 V) for 1000 hours. Conductive heating element 2
Was 250 ° C. during energization. Further, a heat cycle test (maximum temperature 250 ° C., minimum temperature 20 ° C.) of the heater substrate of this example was performed for 1000 hours.

In both the continuous conduction test and the heat cycle test, no peeling occurred between the conductive heating element and the electrode pattern, and no partial defect occurred in the conductive heating element. The reason that no peeling occurred between the electrode pattern and the conductive heating element was that the conductive heating element covered the electrode pattern had a thickness of several hundred μm, which was extremely thin, and the heater was not used for a long time. This is considered to be because the use of the substrate is less susceptible to expansion and contraction due to heat.

The reason that the conductive heating element did not have any partial defects is that the terminal portion of the electrode pattern was formed so as to extend over the entire width of the conductive heating element. After reaching the entire width, it flows into the conductive heating element. For this reason, it is considered that the current flows uniformly throughout the conductive heating element.

Comparative Example 1 In this comparative example, an electrode thin plate is used instead of the electrode pattern of the first embodiment (see FIG. 4). The electrode thin plate is made of carbon having a low resistance value and has a thickness of 3 mm.
Other configurations are the same as those of the first embodiment. An energization test was performed on the heater substrate of this comparative example in the same manner as in the first embodiment. As a result, in 950 hours, the electrode thin plate was peeled off, and power could not be supplied. A thermal cycle test was performed in the same manner as in the first embodiment. As a result, after the elapse of 980 hours, current was partially peeled off and current concentration occurred, and the electrode thin plate locally became abnormally high in temperature, glowed red, and cracked and melted. Eventually, power could not be supplied.

[0023]

According to the present invention, it is possible to provide a heater substrate capable of reducing the thickness of the electrode holding portion and preventing the electrode from peeling off due to heat.

[Brief description of the drawings]

FIG. 1 is an explanatory view of an arrangement of electrode patterns in a first embodiment.

FIG. 2 is an explanatory cross-sectional view of a heater substrate according to the first embodiment.

FIG. 3 is a perspective view of a heater substrate according to the first embodiment.

FIG. 4 is a perspective view of a conventional heater substrate.

FIG. 5 is a sectional view of a conventional heater substrate.

FIG. 6 is a perspective view of a connection member in a conventional example.

[Explanation of Codes] . . Electrode pattern, 11. . . Terminal part, 12. . . Terminal part, 2. . . 4. a conductive heating element; . . Wiring, 6. . . 6. far infrared, . . Crystallized glass, 8. . . Heater board,

Continued on the front page F term (reference) 3K034 AA05 AA10 AA34 AA37 BB05 BB14 BC12 BC29 CA02 CA03 CA14 CA15 CA22 CA27 CA32 EA07 FA25 3K092 QA05 QB19 QB31 QB75 QB76 QC02 QC07 QC16 QC25 QC49 RF34 V17 RF22 V0322

Claims (5)

[Claims] 1. A heater characterized in that an electrode pattern made of a noble metal is printed and baked on crystallized glass, and then a conductive heating element is printed and baked so as to cover at least a part of the electrode pattern. substrate. 2. The heater substrate according to claim 1, wherein the noble metal forming the electrode pattern is made of one or more of silver, palladium, and gold. 3. The electrode pattern according to claim 1, wherein the electrode pattern has a terminal portion having the same width as a width of the conductive heating element, and the terminal portion is covered with the conductive heating element. And the heater substrate. 4. The method according to claim 1, wherein:
A heater substrate, wherein a terminal portion protrudes from a center of the terminal portion. 5. The method according to claim 1, wherein:
A heater substrate, wherein the conductive heating element is made of carbon.