Titanium heater

Abstract

Provided is a titanium heater capable of ensuring sufficient adhesion strength between a metallic titanium substrate and an insulating layer. A titanium heater according to the present invention comprises: a metallic titanium substrate (40); a heating resistor layer (10) that generates heat when energized; and an insulating layer (20) that is layered between the metallic titanium substrate (40) and the heating resistor layer (10) and electrically insulates the metallic titanium substrate (40) and the heating resistor layer (10). A buffer layer (30) comprising at least one layer for mitigating the difference between the thermal expansion of the metallic titanium substrate (40) and the thermal expansion of insulating layer (20) is layered between the metallic titanium substrate (40) and the insulating layer (20).

Description

Titanium heater

[0001] This invention relates to a titanium heater. More specifically, it relates to a titanium heater capable of ensuring sufficient adhesion strength between a metallic titanium substrate and an insulating layer.

[0002] Conventionally, heaters incorporating a heat-generating resistor are known. This heater functions by heating a heat-generating resistor wire provided by the heat-generating resistor by passing an electric current through it, and using a substrate to which the heat from the heated heat-generating resistor wire has been conducted. The inventors have disclosed a heater using stainless steel as the substrate (see, for example, Patent Document 1). The heater described in Patent Document 1 comprises a long base portion, a resistance heating wiring portion having a plurality of parallel wires that generate heat when energized and formed on the surface side or inside the base portion in an electrically insulated state relative to the base portion, and at least two power supply terminal portions, and a power supply electrode portion that electrically connects one terminal portion and the other terminal portion via the resistance heating wiring portion in order to supply power to the resistance heating wiring portion. The resistance heating wiring portion contains a material with a resistance temperature coefficient of 500 to 4,400 ppm / °C, and the parallel wires include an inclined rectangular pattern. With this heater, local temperature rise of the resistance heating wiring portion during use is suppressed, and the object to be heat-treated can be subjected to stable heat treatment while suppressing temperature unevenness, regardless of its size.

[0003] International Publication No. 2013 / 073276

[0004] However, recent heater requirements demand substrate materials that are lighter, more corrosion-resistant, and stronger. Therefore, it is believed that using titanium metal for the heater substrate can resolve this issue. In the case of heaters using metal substrates, adhesion between the substrate and the insulating layer is ensured by using an insulating layer with an appropriate coefficient of thermal expansion. However, when creating a heater using a different metal substrate than conventional heaters, the difference in the coefficient of thermal expansion of the insulating layer required for bonding to the metal substrate necessitates a fresh design for the insulating layer for each metal material. If existing insulating layer materials (hereinafter referred to as "existing materials") with mass production experience can be used, quality can be guaranteed, thus reducing development time and costs. However, bonding an insulating layer using existing materials to a titanium metal substrate may not ensure sufficient adhesion due to differences in thermal expansion coefficients. This invention aims to solve the above problem and provide a titanium heater capable of ensuring sufficient adhesion between a titanium metal substrate and an insulating layer.

[0005] The present invention is as follows: 1. A titanium heater comprising: a metallic titanium substrate; a heat-generating resistor layer that generates heat when an electric current is passed through it; an insulating layer laminated between the metallic titanium substrate and the heat-generating resistor layer to electrically insulate the metallic titanium substrate and the heat-generating resistor layer; and a buffer layer consisting of at least one layer laminated between the metallic titanium substrate and the insulating layer to mitigate the difference in thermal expansion between the metallic titanium substrate and the insulating layer. 2. The titanium heater according to 1. above, wherein when the thermal expansion coefficient of the metallic titanium substrate is T, the thermal expansion coefficient of the buffer layer is B, and the thermal expansion coefficient of the insulating layer is I, B < T < I. 3. 5.0 × 10 －６ ( / °C) < B < 9.1 × 10 －６1. or 2. The titanium heater according to 2., wherein the temperature is ( / °C). 4. The titanium heater according to 1. or 2., wherein the buffer layer is formed to cover part or all of the metal titanium substrate. 5. The titanium heater according to 4., wherein a part of the buffer layer is removed, and the metal titanium substrate is exposed for the formation of an electrically conductive electrode. 6. The titanium heater according to 1. or 2., wherein a heat-soothing layer having a higher thermal conductivity than the metal titanium substrate is further laminated between the insulating layer and the buffer layer. 7. The titanium heater according to 1. or 2., further comprising a protective layer covering the heating resistor. 8. The titanium heater according to 1. or 2., wherein the heating resistor layer is formed on the insulating layer and comprises a heating resistance wire.

[0006] The titanium heater of the present invention comprises a metallic titanium substrate, a heat-generating resistor layer that generates heat when electricity is applied, and an insulating layer laminated between the metallic titanium substrate and the heat-generating resistor layer to electrically insulate the metallic titanium substrate from the heat-generating resistor layer. A buffer layer consisting of at least one layer is laminated between the metallic titanium substrate and the insulating layer to mitigate the difference in thermal expansion between the metallic titanium substrate and the insulating layer. As a result, the buffer layer absorbs the difference in thermal expansion between the metallic titanium substrate and the insulating layer, mitigating stress concentration and ensuring sufficient adhesion strength between the metallic titanium substrate and the insulating layer. Furthermore, it is possible to prevent the metallic titanium substrate and the insulating layer from delaminating due to stress concentration at the interface caused by differences in dimensional changes between the metallic titanium substrate and the insulating layer due to temperature changes. Furthermore, if the thermal expansion coefficient of the titanium substrate is T, the thermal expansion coefficient of the buffer layer is B, and the thermal expansion coefficient of the insulating layer is I, then when B < T < I, by setting the thermal expansion coefficient of the intermediate buffer layer to be smaller than that of the titanium and insulating layers, the difference in thermal expansion can be absorbed, and the adhesion can be further improved by applying appropriate compression between the titanium and insulating layers. More specifically, 5.0 × 10 －６ ( / °C) < B < 9.1 × 10 －６When the temperature is ( / °C), the adhesion strength between the metallic titanium and the insulating layer can be more effectively increased. Furthermore, if the buffer layer is formed to cover part or all of the metallic titanium substrate, oxidation of the metallic titanium at the covered area can be prevented. In addition, if a portion of the buffer layer is removed, providing an exposed metallic titanium substrate for forming an electrically conductive electrode, the electrode formed on the exposed metallic titanium substrate can be connected to an inspection device to test the insulation between it and the heat-retaining resistor layer. Furthermore, if a heat-soothing layer with a higher thermal conductivity than the metallic titanium substrate is further laminated between the insulating layer and the buffer layer, the heat fluctuations generated in the heat-retaining resistor layer can be smoothed out. In addition, by further providing a protective layer covering the heat-retaining resistor layer, it becomes a practical heater. Furthermore, if the heat-retaining resistor layer is formed on the insulating layer and includes a heat-retaining resistance wire, it can be a heater with excellent accuracy.

[0007] Figure 1 is a schematic cross-sectional view of a titanium heater according to an embodiment. Figure 1 is a schematic plan view of Figure 1. Figure 2 is a schematic cross-sectional view of a titanium heater according to another embodiment. Figure 3 is a schematic cross-sectional view of a titanium heater according to yet another embodiment. Figure 4 is a schematic cross-sectional view of a titanium heater according to yet another embodiment. Figure 5 is a schematic explanatory diagram showing the manufacturing process of a titanium heater, where (a) is the step of preparing a metallic titanium substrate, (b) is the step of covering the metallic titanium substrate with a buffer layer material, (c) is the step of forming an electrode material on the exposed portion of the metallic titanium substrate of the buffer layer, and (d) is the step of forming a buffer layer by firing. Figure 7 is a schematic explanatory diagram showing the step of forming a resistive heating element layer on an insulating layer, (b) is the step of forming a protective layer material, and (c) is the step of forming an insulating layer by firing. Figure 8 is a schematic explanatory diagram showing the step of forming a power supply terminal and a power supply line on an insulating layer, and (b) is the step of forming a heating resistor. Following Figure 9, (a) is a schematic explanatory diagram showing the process of laminating protective layer material layers, and (b) is a schematic explanatory diagram showing the process of forming an insulating layer by firing. In relation to an example, (a) shows a state in which a buffer layer has been formed on a metallic titanium substrate, and (b) is a schematic cross-sectional view. Following Figure 11, (a) shows a state in which an insulating layer has been formed, and (b) is a schematic cross-sectional view. Following Figure 12, (a) shows a state in which a power supply terminal and power supply line have been formed, and (b) is a schematic cross-sectional view. Following Figure 13, (a) shows a state in which a heating resistance wire has been formed, and (b) is a schematic cross-sectional view. Following Figure 14, (a) shows a state in which a protective layer has been formed, and (b) is a schematic cross-sectional view.

[0008] The present invention will be described in detail below with reference to embodiments. The matters described herein are illustrative and intended to illustrate embodiments of the present invention, and are intended to provide what is considered to be the most effective and straightforward explanation of the principles and conceptual features of the present invention. In this regard, it is not intended to show structural details of the present invention beyond what is necessary for a fundamental understanding of the invention, and the description, in conjunction with the drawings, will make it clear to those skilled in the art how some forms of the present invention are actually realized.

[0009] <Titanium Heater> As shown in Figure 1, the titanium heater 1 comprises a metallic titanium substrate 40, a heat-generating resistor layer 10 that generates heat when an electric current is passed through it, and an insulating layer 20 laminated between the metallic titanium substrate 40 and the heat-generating resistor layer 10 to electrically insulate the metallic titanium substrate 40 and the heat-generating resistor layer 10. Furthermore, a buffer layer 30 consisting of at least one layer is laminated between the metallic titanium substrate 40 and the insulating layer 20 to mitigate the difference in thermal expansion between the metallic titanium substrate 40 and the insulating layer 20. In other words, the titanium heater 1 comprises a metallic titanium substrate 40, a buffer layer 30 laminated on the metallic titanium substrate 40, an insulating layer 20 laminated on the buffer layer 30, and a heat-generating resistor layer 10 laminated on the insulating layer 20.

[0010] [1] Metal Titanium Substrate The metal titanium substrate 40 is a substrate made of metallic titanium. The term "substrate" includes not only plate-shaped bodies but also housings. For example, an electrostatic chuck housing is also included in the "substrate". Furthermore, "metal titanium" may be 100% pure titanium, but may also contain 10% or less of other metals (e.g., aluminum, vanadium, chromium, etc.). The metal titanium substrate 40 is not particularly limited as long as it is plate-shaped, but it is preferably 0.2 to 4 mm thick, and more preferably 0.3 to 3.5 mm thick. Furthermore, if the metal titanium substrate is in the form of a housing, it is preferably 30 to 300 mm thick, and more preferably 50 to 200 mm thick. Here, the coefficient of thermal expansion of the metal titanium substrate 40 is 8.4 × 10⁻⁶ －６ It is ( / ℃).

[0011] [2] Heating resistor layer The heating resistor layer 10 is not particularly limited as long as it is a layer that generates heat upon energization. As shown in FIG. 1, it includes a power supply terminal 11 and a heating resistor wire 12. In FIG. 1, illustration of the power supply wire 90 (see FIG. 2) that connects the power supply terminal 11 and the heating resistor wire 12 is omitted. As shown in FIGS. 1 and 2, the power supply terminal 11, the heating resistor wire 12, and the power supply wire 90 are preferably formed on the insulating layer 20. For the materials of the power supply terminal 11 and the power supply wire 90, for example, silver with high conductivity can be used. The thickness of the power supply terminal 11 and the power supply wire 90 is not particularly limited, but it is preferably 8 to 50 μm, and more preferably 10 to 40 μm. The heating resistor wire 12 can be made into a zigzag shape by combining parallel wiring and folded-back wiring, so that heat can be uniformly generated over the entire surface of the substrate. The thickness of the heating resistor wire 12 is not particularly limited, but it is preferably 8 to 40 μm, and more preferably 10 to 30 μm. The material of the heating resistor wire 12 is not particularly limited, but a conductive material that can generate heat according to the resistance value upon energization can be used. This conductive material is not particularly limited, and for example, silver, copper, platinum, palladium, rhodium, tungsten, molybdenum, rhenium, ruthenium, etc. can be used. These can be used alone or in combination of two or more. When two or more are used in combination, they can be made into an alloy. For example, silver-palladium alloy, silver-platinum alloy, platinum-rhodium alloy, silver-ruthenium alloy, etc. can be used.

[0012] [3] Insulating layer The insulating layer 20 is laminated between the metal titanium substrate 40 and the heating resistor layer 10, and serves to electrically insulate the metal titanium substrate 40 and the heating resistor layer 10. The thermal expansion coefficient of the insulating layer 20 is not particularly limited, but it is preferably 8.8×10 －６ ( / °C) to 9.4×10 －６ ( / °C), and more preferably 9.0×10 －６ ( / °C) to 9.2×10 －６It is even more preferable that the temperature is ( / °C). The material of the insulating layer 20 is not particularly limited, but glass, ceramics, glass-ceramics, etc. are preferred. In particular, glass is preferred from the viewpoint of the thermal expansion balance between the insulating layer 20 and the metallic titanium substrate 40, and crystallized glass and semi-crystallized glass are preferred. Specifically, SiO ２ - Al ２ O ３ - MO-based glass is preferred. Here, MO is an oxide of an alkaline earth metal (MgO, CaO, BaO, SrO, etc.). The thickness of the insulating layer 20 is not particularly limited, but is preferably 80 to 120 μm, and more preferably 90 to 110 μm. The insulating layer 20 may consist of one layer or multiple layers. For example, as in the titanium heater 5 described later, it may consist of three insulating layers 25. To form an insulating layer consisting of multiple layers, for example, the first insulating layer can be formed by screen printing, dried and fired, and then the second and third insulating layers can be laminated on top of the first insulating layer in the same manner.

[0013] [4] Buffer layer The buffer layer 30 is a layer for mitigating the difference in thermal expansion between the titanium metal substrate 40 and the insulating layer 20. The buffer layer 30 is not particularly limited as long as it can mitigate the difference in thermal expansion between the titanium metal substrate 40 and the insulating layer 20, but when the thermal expansion coefficient of the titanium metal substrate 40 is T, the thermal expansion coefficient of the buffer layer 30 is B, and the thermal expansion coefficient of the insulating layer 20 is I, for example, it can be as follows: That is, B < I, and B < T, preferably B < I and T, and more preferably B < T < I. In the above relationship, the thermal expansion coefficient I of the insulating layer 20 is 8.8 × 10 －６ ~9.4 x 10 －６ It can be set to ( / °C). Also, the coefficient of thermal expansion T of the titanium metal substrate 40 is usually 8.4 × 10 －６ ( / °C). Furthermore, the thermal expansion coefficient B of the buffer layer 30 is smaller than the thermal expansion coefficient I of the insulating layer 20 and the thermal expansion coefficient T of the titanium metal substrate 40, for example, 5.0 to 9.1 × 10 －６ It can be expressed as ( / ℃), 5.0 × 10 －６The above and 8.4 × 10 －６ It is preferable that the temperature is less than ( / °C), and 6.0 to 8.0 × 10 －６ It is even more preferable that the temperature is ( / °C). By setting the thermal expansion coefficient B of the buffer layer 30 laminated between the metallic titanium substrate 40 and the insulating layer 20 to be smaller than the thermal expansion coefficient T of the metallic titanium substrate 40 and the thermal expansion coefficient I of the insulating layer 20, it is thought that the adhesion can be further improved by applying appropriate compression between the metallic titanium substrate 40 and the insulating layer 20. In addition, it is possible to prevent the metallic titanium substrate 40 and the insulating layer 20 from delaminating due to differences in dimensional changes between the metallic titanium substrate 40 and the insulating layer 20 caused by temperature changes, which would cause stress to concentrate at the interface.

[0014] The material of the buffer layer 30 is not particularly limited, but glass, ceramics, glass-ceramics, etc. are preferred. Glass is particularly preferred from the viewpoint of the thermal expansion balance between the insulating layer 20 and the metallic titanium substrate 40, and crystallized glass and semi-crystallized glass are preferred. Specifically, SiO ２ - Al ２ O ３ - MO-based glass is preferred. Here, MO is an oxide of an alkaline earth metal (MgO, CaO, BaO, SrO, etc.). The thickness of the buffer layer 30 is not particularly limited, but is preferably 8 to 120 μm, and more preferably 10 to 60 μm. The buffer layer 30 consists of at least one layer, and may consist of two or more layers. By providing two or more buffer layers, the difference in thermal expansion can be gradually reduced, thereby mitigating the difference in thermal expansion. To form an insulating layer consisting of multiple layers, for example, the first buffer layer can be formed by screen printing, dried, and fired, and then the second and third buffer layers can be laminated on top of the first buffer layer in the same manner.

[0015] Furthermore, the buffer layer 30 can be formed to cover part or all of the metallic titanium substrate 40. That is, as in the titanium heater 1, the buffer layer 30 can be laminated only on the surface, which is part of the metallic titanium substrate 40, or it can be formed to cover one or more of the surface, back surface, both sides, or all of the metallic titanium substrate 40. The buffer layer 35 of the titanium heater 2 shown in Figure 3 is formed to cover the entire surface of the metallic titanium substrate 40. Metallic titanium is easily oxidized, and oxidation progresses particularly easily at high temperatures. Therefore, by covering the entire surface of the metallic titanium substrate 40 with the buffer layer 30, the surface of the metallic titanium substrate 40 can be protected. However, it is preferable to have a metallic titanium substrate exposed portion 40e for forming an electrically conductive electrode, where a part of the buffer layer 35 has been removed. When a metallic titanium substrate exposed portion 40e is provided, an electrode (not shown) can be provided on the metallic titanium substrate exposed portion 40e, and the insulation between the electrode and the heating resistor layer 10 can be tested by connecting the electrode to a testing device. Furthermore, in addition to forming electrodes separately, it is also possible to remove a portion of the buffer layer 30 formed after the heater is completed for oxidation prevention purposes, partially exposing the metallic titanium substrate 40, and evaluating its conductivity as an electrode. The other components of the titanium heater 2 are the same as those of the titanium heater 1, and their effects are also the same, so their explanation is omitted.

[0016] [5] The uniform heat layer titanium heater can be further laminated between the insulating layer and the buffer layer with a uniform heat layer having a higher thermal conductivity than the metallic titanium substrate. As shown in Figure 4, the titanium heater 3 has a uniform heat layer 50 having a higher thermal conductivity than the metallic titanium substrate 40 further laminated between the insulating layer 20 and the buffer layer 30. The thickness of the uniform heat layer 50 is not particularly limited, but is preferably 1 to 250 μm, and more preferably 3 to 30 μm. This uniform heat layer 50 has the role of leveling out the thermal fluctuations formed in the heat-generating resistor layer 10. That is, if there is a drop in the heating temperature, it can raise the temperature to the same as the surrounding temperature, and if there is a spike in the heating temperature, it can lower the temperature to the same as the surrounding temperature, thereby leveling out the thermal fluctuations. It is particularly suitable when the heat-generating resistor layer 10 is formed using a resistive heating wiring having a predetermined pattern shape, in order to level out the thermal fluctuations caused by this pattern shape. In other words, the pattern shape creates areas where resistive heating wiring exists and areas where it does not, forming thermal fluctuations where the areas with resistive heating wiring have a higher temperature than the areas without it. These thermal fluctuations can be smoothed out by passing the material through the heat-sensing layer 50, thereby reducing the temperature difference.

[0017] The heat-stable layer 50 can be formed from a material with a higher thermal conductivity than the material constituting the titanium metal substrate 40. Specifically, silver, copper, gold, aluminum, tungsten, nickel, etc., or alloys containing at least one of these metals can be used as the thermally conductive metal. These thermally conductive metals may be used individually or in combination of two or more. Among these, silver, copper, aluminum, and alloys containing at least one of these are preferred. The heat-stable layer 50 can be formed in any way. Specifically, the heat-stable layer 50 can be provided as a plating layer (electroless plating layer, electroplating layer, composite plating layer, etc.). Alternatively, the heat-stable layer 50 can be formed by printing a paste containing a thermally conductive material and then baking the printed coating. For example, a printing paste containing metal particles (metal powder) can be used as the thermally conductive material. In this case, the printing paste may contain not only metal particles but also a vehicle for pasteurization and glass or ceramic components as a co-foundation. The other components of titanium heater 3 are the same as those of titanium heater 1, and their effects are also the same, so their explanation is omitted.

[0018] As shown in Figure 5, the titanium heater 4 further includes a protective layer 60 and electrodes 70 covering the heating resistor 10 in the titanium heater 2. [6] Protective layer The protective layer 60 is a layer that protects the resistive heating wire 12 and electrodes 11 constituting the heating resistor 10 from the outside, and is intended for insulation. The material is preferably glass, ceramics, glass-ceramics, etc., similar to the insulating layer 20. Glass is particularly preferred from the viewpoint of the thermal expansion balance between the insulating layer 20 and the metallic titanium substrate 40, and crystallized glass and semi-crystallized glass are preferred. Specifically, SiO ２ - Al ２ O ３ - MO-based glass is preferred. Here, MO is an oxide of an alkaline earth metal (MgO, CaO, BaO, SrO, etc.). The thickness of the insulating layer 20 is not particularly limited, but is preferably 80 to 120 μm, and more preferably 90 to 110 μm. The protective layer 60 may consist of one layer or multiple layers.

[0019] The titanium heater 4 is further equipped with electrodes 70. The electrodes 70 are formed by printing and firing electrode material onto the exposed portion 40e of the titanium substrate. These electrodes 70 are useful for testing the insulation between them and the heat-generating resistor layer 10. The material of the electrodes 70 can be made mainly of silver, copper, platinum, or gold (i.e., 50% by mass or more, preferably 70% by mass or more, particularly 90% by mass or more, and may even be 100% by mass). The other components of the titanium heater 4 are the same as those of the titanium heater 3, and their effects are also the same, so their explanation is omitted.

[0020] Figure 6 shows a titanium heater 5 implemented in an electrostatic chuck. The titanium heater 5 comprises a metallic titanium substrate 40, a heat-generating resistor layer 15, and an insulating layer 25 consisting of three layers with a total thickness of 100 μm. A buffer layer 35 with a thickness of 15 μm is laminated between the metallic titanium substrate 40 and the insulating layer 25. The buffer layer 35 is formed to cover the entire surface of the metallic titanium substrate 40 with a constant thickness. In addition, a portion of the metallic titanium substrate exposed 40e is formed in the buffer layer 35, and this exposed portion 40e is equipped with an electrode portion 70. Furthermore, a heat-soothing layer 51 with a thickness of 10 μm is provided between the insulating layer 25 and the buffer layer 35. A protective layer 67 with a thickness of 660 μm is laminated on top of the insulating layer 25. The protective layer 67 consists of a first protective layer 65 comprising nine layers with a total thickness of 330 μm, and a second protective layer 66 comprising nine layers with a total thickness of 330 μm, which is laminated on the first protective layer 65.

[0021] The heat-generating resistor layer 15 is formed on the insulating layer 25 and has a heat-generating resistor wire 12 with a thickness of 20 μm, a power supply terminal 11 with a thickness of 15 μm connected to one end 12a and the other end 12b of the heat-generating resistor wire 12, and a power supply line 90. Each power supply terminal 11 is connected to the power supply 80 via power supply lines 97 and 98. The electrostatic chuck circuit 16 is formed on the first protective layer 65 and has a power supply terminal 13 and a power supply line 90. Each power supply terminal 13 is connected to the power supply 81 via power supply lines 95 and 96.

[0022] <Manufacturing Method for Titanium Heaters> The manufacturing method for titanium heaters will be described in detail below with reference to Figures 7 to 10. The manufacturing method shown below is illustrative, and the manufacturing method of the present invention is not limited to the following example. (1) Buffer Layer Formation Process The buffer layer formation process is a process of forming a buffer layer on a metallic titanium substrate 40. As shown in Figure 7(a), a metallic titanium substrate (pure titanium) 40 is prepared. The structure of the metallic titanium substrate 40 is as described above. First, a buffer layer is formed on the metallic titanium substrate 40. In this manufacturing process, as shown in Figure 7(b), the case in which a buffer layer 30 having an exposed metallic titanium substrate portion 40e is formed on the entire surface of the metallic titanium substrate 40 will be explained as an example. Note that as shown in Figure 1, the buffer layer 30 can also be formed only on the surface of the metallic substrate 40. In order to form the buffer layer 35, the thermal expansion coefficient must be 6.0 × 10 －６ ( / °C) ~ 8.0 × 10 －６ The process involves preparing a buffer layer material 35A with a temperature of ( / °C), forming buffer layer material layers 35a, 35b, 35c, and 35d on the surface 40a, back surface 40b, and side surfaces 40c and 40d of the titanium metal substrate 40, respectively, and then drying and firing them. The method for forming the buffer layer material layers 35a, 35b, 35c, and 35d is not particularly limited, and they can be formed, for example, by screen printing. Specifically, the buffer layer material 35A can be laminated onto any surface of the titanium metal substrate 40, for example, the surface 40a, by screen printing and dried, and then similarly, the buffer layer material layers 35b, 35c, and 35d can be sequentially laminated onto the back surface 40b and side surfaces 40c and 40d, and dried. The drying conditions are not particularly limited, but it is preferable to heat at a temperature of 110 to 130°C under atmospheric conditions, and more preferably at a temperature of 115 to 125°C. Furthermore, the heating time is preferably 10 to 30 minutes, and more preferably 15 to 25 minutes.

[0023] Next, if necessary, electrodes 70 are formed on the exposed portion 40e of the titanium metal substrate. As shown in Figure 7(c), the conductive paste 70a, which is the material for the electrodes 70, is formed on the exposed portion 40e of the titanium metal substrate, for example, by screen printing. An unfired buffer layer 32 is obtained by firing the unfired buffer layer 32. As shown in Figure 7(d), a buffer layer 37 is obtained by firing the unfired buffer layer 32. There are no particular limitations on the heating conditions, but it is preferable to heat under atmospheric conditions, and the heating temperature is preferably 800 to 900°C, and more preferably 830 to 870°C. The heating time is preferably 5 to 15 minutes, and more preferably 8 to 12 minutes. A buffer layer 37 consisting of a buffer layer 35 and electrodes 70 is obtained. As described above, when forming electrodes 70, it is preferable to form the electrode material 70a at the stage of the unfired buffer layer 32 before firing. This is because if the exposed portion 40e of the titanium metal substrate is fired while exposed, there is a risk that the exposed portion will oxidize.

[0024] (2) Insulating layer formation process The insulating layer formation process is a process of forming an insulating layer on the buffer layer 37. As shown in Figure 8(a), a heat-soothing layer 51 can be formed on the surface of the buffer layer 37. The heat-soothing layer 51 may be formed in any way. Specifically, the heat-soothing layer 51 can be provided as a plating layer (electroless plating layer, electroplating layer, composite plating layer thereof, etc.). Alternatively, the heat-soothing layer 51 can be formed by printing a paste containing a thermally conductive material and then baking the printed coating. For example, a printing paste containing metal particles (metal powder) can be used as the thermally conductive material. In this case, the printing paste may contain not only metal particles but also a vehicle for paste formation and glass or ceramic components as a co-material. Note that the formation of the heat-soothing layer 51 is performed as needed, and the insulating layer described later may be provided directly on the buffer layer 37.

[0025] As shown in Figure 1, the insulating layer may be formed from only one layer, but it can also consist of multiple layers. For example, the insulating layer 21 shown in Figure 8(c) is formed from three layers. To form this insulating layer 21, first, an insulating layer material layer 21a is formed as the first layer. The insulating layer material for forming the insulating layer material layer 21a can be the same insulating layer material shown in the titanium heater. As shown in Figure 8(b), the insulating layer material layer 21a can be formed by applying an insulating layer material. This insulating layer material can be prepared by mixing the material with an organic binder or the like to make a paste. The insulating layer material can be applied to one surface by screen printing.

[0026] Next, the formed insulating layer material layer 21a is dried. There are no particular limitations on the drying conditions, but it is preferable to dry under atmospheric conditions, and the drying temperature is preferably 110 to 130°C, and more preferably 115 to 125°C. The drying time is preferably 10 to 30 minutes, and more preferably 15 to 25 minutes. Next, the insulating layer material layer 21a is fired by heating. There are no particular limitations on the heating conditions, but it is preferable to heat under atmospheric conditions, and the heating temperature is preferably 800 to 900°C, and more preferably 830 to 870°C. The heating time is preferably 5 to 15 minutes, and more preferably 8 to 12 minutes. As a result, the first insulating layer 211 is formed. Next, the second insulating layer material layer 21b is formed in the same manner, and then dried and fired to form the second insulating layer 212. Furthermore, the third insulating layer material layer 21c is formed in the same manner, and then dried and fired to form the third insulating layer 213. As a result, an insulating layer 21 consisting of three layers is formed.

[0027] (3) Heat-Resisting Layer Formation Process The heat-retaining layer formation process is a process of forming a heat-retaining layer on the insulating layer. First, as shown in Figure 9(a), a power supply terminal 11 and a power supply line 90 are formed on the insulating layer 21. The material of the power supply terminal 11 can be a low-resistance material, for example, silver. The same applies to the material of the power supply line 90. It is preferable to form both the power supply terminal 11 and the power supply line 90 simultaneously by screen printing. After forming the unfired power supply terminal and unfired power supply line by printing, they are dried. There are no particular limitations on the drying conditions, but it is preferable to dry them under atmospheric conditions, and the drying temperature is preferably 110 to 130°C, and more preferably 115 to 125°C. The drying time is preferably 10 to 30 minutes, and more preferably 15 to 25 minutes. Next, they are fired by heating. There are no particular limitations on the heating conditions, but it is preferable to heat under atmospheric conditions, and the heating temperature is preferably 800 to 900°C, and more preferably 830 to 870°C. The heating time is preferably 5 to 15 minutes, and more preferably 8 to 12 minutes. As a result, the power supply terminal 11 and the power supply line 90 are formed on the insulating layer 21.

[0028] Next, as shown in Figure 9(b), the heating resistance wire 12 is formed. The material for the heating resistance wire can be the same as the material for the heating resistance wire shown for the titanium heater. The heating resistance wire 12 is preferably formed by screen printing. After the unfired heating resistance wire is formed by printing, it is dried and then fired by heating. The drying and heating conditions are the same as those for forming the power supply terminal 11 and the power supply wire 90, so their explanation is omitted.

[0029] (4) Protection Layer Formation Step The protection layer formation step is a step of forming a protection layer for coating the heating resistor layer. The method of forming the protection layer is not particularly limited and may be formed from only one layer, but it can be composed of multiple layers. For example, the protection layer 61 shown in Fig. 10(b) is formed from three layers. To form this protection layer 61, first, as the first layer, a protection layer material layer 61a is formed. The protection layer material for forming the protection layer material layer 61a can use the material of the protection layer shown by the titanium heater as it is. As shown in Fig. (a) of the same figure, the protection layer material layer 61a can be formed by applying the protection layer material. This protection layer material can be prepared by mixing an organic binder or the like with the above material to make it into a paste form. For application, it can be applied to one side by screen printing.

[0030] Next, the formed protection layer material layer 61a is dried. The drying conditions are not particularly limited, but it is preferably dried under atmospheric conditions. The drying temperature is preferably 110 - 130°C, and more preferably 115 - 125°C. The drying time is preferably 10 - 30 minutes, and more preferably 15 - 25 minutes. Next, the protection layer material layer 61a is fired by heating. The heating conditions are not particularly limited, but it is preferably heated under atmospheric conditions. The heating temperature is preferably 800 - 900°C, and more preferably 830 - 870°C. The heating time is preferably 5 - 15 minutes, and more preferably 8 - 12 minutes. Thus, the first layer of the protection layer 611 is formed. Next, similarly, the second layer of the protection layer material layer 61b is formed, dried and fired under the same conditions to form the second layer of the protection layer 612. Further, similarly, the third layer of the protection layer material layer 61c is formed, dried and fired under the same conditions to form the third layer of the insulation layer 613. Thus, the protection layer 61 composed of three layers is formed. In this way, the titanium heater 6 is manufactured.

[0031] The present invention will be described in more detail below with reference to examples. [Example 1] (Fabrication of Titanium Heater) The titanium heater according to the example was fabricated by the following procedure. (1) Formation of Buffer Layer A metal titanium substrate (pure titanium) 40 with a length of 40 mm, a width of 30 mm, and a thickness of 3 mm was prepared, and a glass paste (containing Si, Al and alkaline earth metal elements, with a thermal expansion coefficient of 7.7 × 10) was prepared as a buffer layer material to form a buffer layer 36 on its surface. －６ A coating film was formed by screen printing a semi-crystalline glass powder (at a temperature of 1 / °C) using a printing mask with a frame size of 800 mm x 800 mm, mesh #150, and emulsion thickness of 10 μm. The coating was then dried in a drying oven at 120°C for 20 minutes under atmospheric conditions. The same printing and drying process was then performed on the back surface and both sides. After that, the coating was heated in a firing oven at 850°C for 10 minutes. In this way, a buffer layer 36 with a thickness of 15 μm was formed, as shown in Figures 11(a) and (b). The thermal expansion coefficient of this buffer layer is shown in Table 1. The same temperature profile was used for firing the insulating layer 22, circuit patterns (power supply terminals, heating resistance wires, power supply wires), and protective layer described below.

[0032] (2) Formation of insulating layer As shown in Figure 12(b), an insulating layer 22 consisting of three layers (insulating layers 221, 222, and 223) was formed. First, the insulating layer 221 was formed on the surface of the buffer layer 36 under the same conditions as above, using a glass paste (containing Si, Al and alkaline earth metal elements, with a thermal expansion coefficient of 9.1 × 10) which has a different thermal expansion coefficient from the buffer layer material. －６ A coating film was formed by screen printing a semicrystalline glass powder (at 0°C / °F). Next, it was fired under the same conditions as in (1) above and cooled to form an insulating layer 221 with a thickness of 35 μm. On the surface of the insulating layer 221, an insulating layer 222 with a thickness of 35 μm was formed by screen printing, drying, firing, and cooling a glass paste with the same composition as the insulating layer 221. Furthermore, an insulating layer 223 with a thickness of 35 μm was formed by screen printing, drying, firing, and cooling a glass paste with the same composition as the insulating layer 221. As a result, an insulating layer 22 with a thickness of 105 μm was formed, consisting of three layers (insulating layers 221, 222, and 223).

[0033] (3) Formation of the heating resistor layer First, a conductive paste containing silver powder was printed on the surface of the insulating layer 22 (223) using a mask, and then fired in the same manner as above to form a power supply terminal 11 and a power supply line 90 with a thickness of 15 μm as shown in FIGS. 13(a) and (b). Next, a resistor paste containing silver and palladium was printed on the surface of the same insulating layer 22 (223) using a mask to form a heating resistor wire 12 with a thickness of 15 μm. As a result, as shown in FIGS. 14(a) and (b), a heating resistor layer 16 composed of the power supply terminal 11, the heating resistor wire 12, and the power supply line 90 was formed.

[0034] (4) Formation of the protective layer As shown in FIG. 15(b), a protective layer 62 composed of two layers (protective layers 621 and 622) was formed. First, a glass paste containing glass powder for the protective layer was screen-printed on the exposed portion of the insulating layer 22 and the surface of the heating resistor layer 15 to form a coating film. Next, it was dried, fired, and cooled under the same conditions as in (2) above to form a first-layer protective layer 621 with a thickness of 35 μm. Furthermore, a glass paste with the same composition was screen-printed, dried, fired, and cooled under the same conditions to form a protective layer 622 with a thickness of 35 μm. As a result, a protective layer 62 with a thickness of 70 μm composed of two layers (protective layers 621 and 622) was formed. Thus, the titanium heater of Example 1 was manufactured.

[0035] [Examples 2 to 5] As shown in Table 1, in Examples 2 to 5, a titanium heater was manufactured using a buffer layer material for forming the buffer layer 36 made of a material having a different coefficient of thermal expansion from that of Example 1. All other conditions were the same as those of Example 1.

[0036]

[0037] <Evaluation of Adhesion> (Test Method) Six test specimens were prepared for each of Examples 1 to 5. For each test specimen, adhesive tape (product name: Sumilon Tape (manufactured by Sumilon Co., Ltd., product number E-212)) was applied to the three insulating layers and two protective layers after each layer was fired, and a light peeling test was performed. (Test Results) Examples 1 to 4: No peeling was observed up to the final layer for all six test specimens. Example 5: No peeling was observed after the first insulating layer was fired for four out of the six test specimens. It is believed that by setting the thermal expansion coefficient of the buffer layer 36 laminated between the titanium metal substrate 40 and the insulating layer 22 to be smaller than the thermal expansion coefficient of titanium metal and the thermal expansion coefficient of the insulating layer 22, adhesion can be improved by applying appropriate compression between the titanium metal substrate 40 and the insulating layer 22.

[0038] The titanium heater of the present invention is industrially applicable in the field of metal heaters. In particular, it is industrially applicable in the field of metal heaters equipped with a substrate that is lightweight, corrosion-resistant, and has excellent strength.

[0039] 1, 2, 3, 4, 5, 6: Titanium heater; 10, 15, 16: Heating resistance layer; 20, 21 (211, 212, 213), 22 (221, 222, 223), 25: Insulating layer; 30, 35, 36: Buffer layer; 40: Metal titanium substrate; 40e: Metal titanium substrate exposed portion; 50, 51: Heating uniformity layer; 60, 61 (611, 612, 613), 62 (621, 622), 67 (65, 66): Protective layer; 70: Electrode.

Claims

1. A titanium heater comprising: a metallic titanium substrate; a heat-generating resistor layer that generates heat when an electric current is passed through it; an insulating layer laminated between the metallic titanium substrate and the heat-generating resistor layer to electrically insulate the metallic titanium substrate and the heat-generating resistor layer; and a buffer layer consisting of at least one layer laminated between the metallic titanium substrate and the insulating layer to mitigate the difference in thermal expansion between the metallic titanium substrate and the insulating layer.

2. The titanium heater according to claim 1, wherein when the thermal expansion coefficient of the metallic titanium substrate is T, the thermal expansion coefficient of the buffer layer is B, and the thermal expansion coefficient of the insulating layer is I, B < T < I.

3. 5.0 x 10 －６ ( / °C) < B < 9.1 × 10 －６ The titanium heater according to claim 2, wherein the temperature is ( / °C).

4. The titanium heater according to claim 1 or 2, wherein the buffer layer is formed to cover a part or the entire surface of the metallic titanium substrate.

5. The titanium heater according to claim 4, comprising a portion of the buffer layer removed, which is an exposed portion of a metallic titanium substrate for forming an electrically conductive electrode.

6. The titanium heater according to claim 1 or 2, wherein a heat-soothing layer having a higher thermal conductivity than the metallic titanium substrate is further laminated between the insulating layer and the buffer layer.

7. The titanium heater according to claim 1 or 2, further comprising a protective layer covering the heat-generating resistor layer.

8. The titanium heater according to claim 1 or 2, wherein the heat-generating resistor layer is formed on the insulating layer and comprises a heat-generating resistor wire.

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