Heater

Abstract

The present invention aims to provide a heater with excellent crack resistance. A heater comprising a disc-shaped body and a plurality of wires as heating elements disposed inside the body, wherein the plurality of wires comprises a first wire and a second wire arranged at a distance in a first direction along the thickness of the body, wherein the first wire comprises a first high potential and a first low potential, and the second wire comprises a second high potential and a second low potential, and when viewed toward the first direction, the plurality of wires have an overlapping region in which the first wire and the second wire overlap, wherein the overlapping region comprises a first region and a second region, wherein the first region is an region in which the first high potential and the second high potential overlap, and the second region is an region in which the first low potential and the second low potential overlap, and wherein the average potential difference V between the first wire and the second wire in each of the first region and the second region is smaller than the value obtained by √{(α×ρ×L) / S1}.

Description

Technology Field

[0001] The present disclosure relates to a heater. Background Technology

[0002] Patent Document 1 discloses a heating heater having a placement plate on which a workpiece to be heated is placed. A plurality of heating circuits are embedded within the placement plate. The plurality of heating circuits are arranged in layers with spacing along the thickness of the placement plate. Hereinafter, the placement plate is referred to as the workpiece, and the heating circuits as wiring. Prior art literature

[0003] [Patent Document 1] Japanese Patent Publication No. 2017-174713 The problem to be solved

[0004] When multiple wires are spaced apart along the thickness of the gas, depending on the volume resistivity of the gas and the circuit pattern of the multiple wires, there is a risk that current may leak between adjacent wires in a specific direction, causing the temperature of the gas to rise locally.

[0005] One of the objectives of the present disclosure is to provide a heater with excellent thermal uniformity. means of solving the problem

[0006] The heater of the present disclosure comprises a disc-shaped body and a plurality of wires as heating elements disposed inside the body. The plurality of wires comprises a first wire and a second wire arranged at intervals in a first direction along the thickness of the body. The first wire comprises a first high potential and a first low potential. The second wire comprises a second high potential and a second low potential. The heater of the present disclosure has an overlapping region in which the first wire and the second wire overlap when viewed toward the first direction of the plurality of wires. The overlapping region comprises a first region and a second region. The first region is an area where the first high potential and the second high potential overlap. The second region is an area where the first low potential and the second low potential overlap. The average potential difference V between the first wiring and the second wiring in each of the first region and the second region is smaller than the value calculated by √{(α×ρ×L) / S1}. α is a predetermined allowable heat generation amount, and its unit is W. ρ is the volume resistivity of the gas, and its unit is Ω·m. L is the distance between the first wiring and the second wiring along the first direction, and its unit is mm. S1 is the area of ​​each of the first region and the second region when viewed toward the first direction, and its unit is mm². Effects of the invention

[0007] The heater of the present disclosure has excellent crack resistance. Brief explanation of the drawing

[0008] FIG. 1 is a schematic cross-sectional view showing a heater of embodiment 1. FIG. 2 is a schematic diagram showing an example of a plurality of wires provided in the heater of embodiment 1. Figure 3 is a schematic diagram showing the first wiring illustrated in Figure 2. Figure 4 is a schematic diagram showing the second wiring illustrated in Figure 2. FIG. 5 is a schematic cross-sectional view showing a part of the overlapping area of ​​the first wiring and the second wiring shown in FIG. 2. FIG. 6 is a schematic diagram showing an example of a plurality of wires provided in the heater of embodiment 2. Figure 7 is a schematic diagram showing the second wiring illustrated in Figure 6. Figure 8 is a graph showing the amount of heat generated by the heater and the degree of crack deterioration measured in the test example. Specific details for implementing the invention

[0009] [Description of embodiments of the present disclosure]

[0010] First, embodiments of the present disclosure will be described.

[0011] (1) A heater according to one embodiment of the present disclosure comprises a disc-shaped body and a plurality of wires as heating elements disposed inside the body. The plurality of wires comprises a first wire and a second wire arranged at a distance in a first direction along the thickness of the body. The first wire comprises a first high potential and a first low potential. The second wire comprises a second high potential and a second low potential. The heater has an overlapping area in which the first wire and the second wire overlap when viewed toward the first direction. The overlapping area comprises a first area and a second area. The first area is an area where the first high potential and the second high potential overlap. The second area is an area where the first low potential and the second low potential overlap. The average potential difference V between the first wiring and the second wiring in each of the first region and the second region is smaller than the value calculated by √{(α×ρ×L) / S1}. α is a predetermined allowable heat generation amount, and its unit is W. ρ is the volume resistivity of the gas, and its unit is Ω·m. L is the distance between the first wiring and the second wiring along the first direction, and its unit is mm. S1 is the area of ​​each of the first region and the second region when viewed toward the first direction, and its unit is mm².

[0012] In the heater of (1) above, even if the first wire and the second wire overlap when looking at the plurality of wires in the first direction, the average potential difference V between the first wire and the second wire in the overlapping area is smaller than a specific value. Therefore, in the heater of (1) above, it is difficult for current to leak between the first wire and the second wire. Since it is difficult for current to leak between the first wire and the second wire, it is difficult for the temperature of the gas to rise locally. Therefore, the heater of (1) above has excellent crack resistance.

[0013] (2) In the heater of (1) above, the overlapping area may include two areas: the first area and the second area.

[0014] In the heater of (2) above, when multiple wires are viewed in the first direction and the first wire and the second wire overlap, the high potential parts and the low potential parts overlap. In other words, the high potential parts and the low potential parts do not overlap between the first wire and the second wire. Therefore, it is difficult for current to leak between the first wire and the second wire regardless of the volume resistivity of the gas. With the heater of (2) above, the degree of freedom in selecting the gas material is high.

[0015] (3) In the heater of (1) above, the overlapping region may include at least one of the third region and the fourth region. The third region is the region where the first high potential and the second low potential overlap. The fourth region is the region where the first low potential and the second high potential overlap. The average potential difference V between the first wiring and the second wiring in each of the third region and the fourth region is smaller than the value calculated by √{(α×ρ×L) / S2}. S2 is the area of ​​each of the third region and the fourth region when viewed in the first direction, and the unit is mm².

[0016] In the heater of (3) above, even if a high potential and a low potential overlap between the first wire and the second wire when looking at multiple wires in the first direction, the average potential difference V between the first wire and the second wire in the overlapping area is smaller than a specific value. Therefore, in the heater of (3) above, it is difficult for current to leak even between the high potential and low potential adjacent in the first direction.

[0017] (4) In any one of the heaters (1) to (3) above, the allowable heat output α may be 5 W or less.

[0018] If the allowable heat output is 5 W or less, the degree of deterioration of gas cracks can be reduced to 2°C or less, as shown in the test example described below, for instance.

[0019] (5) In any one of the heaters (1) to (4) above, the first wiring may have a first circuit pattern disposed in an area including the center of the gas. The second wiring may have a second circuit pattern disposed in an annular area surrounding the first circuit pattern, and a first and second outlet disposed from the second circuit pattern toward the center of the gas.

[0020] By arranging the first circuit pattern in an area including the center of the gas and the second circuit pattern in an annular area surrounding the first circuit pattern, the first wiring and the second wiring can be temperature-controlled independently of each other, thereby improving the crack resistance of the heater. By arranging the first and second lead portions from the second circuit pattern toward the center of the gas, the connection points with the terminals of the first and second wiring can be concentrated near the center of the gas.

[0021] (6) In any one of the heaters (1) to (4) above, the first wiring may have a first circuit pattern arranged in an area including the center of the gas. The first circuit pattern may have a plurality of curved sections arranged along different circumferences concentric with the gas, and a plurality of folded sections connecting adjacent curved sections so that the plurality of curved sections are connected in a single line. The plurality of curved sections may have a plurality of first curved sections formed at the first high potential and a plurality of second curved sections formed at the first low potential. A portion of the plurality of first curved sections may have a first section arranged between adjacent second curved sections. A portion of the plurality of second curved sections may have a second section arranged between adjacent first curved sections. The second wiring may have a second circuit pattern arranged in an annular area surrounding the first circuit pattern, a first lead section formed at the second high potential, and a second lead section formed at the second low potential. The first extraction portion may be positioned from the second circuit pattern toward the center of the gas so as not to overlap with the second portion when viewed toward the first direction. The second extraction portion may be positioned from the second circuit pattern toward the center of the gas so as not to overlap with the first portion when viewed toward the first direction.

[0022] In the first circuit pattern, the first curve section is positioned between adjacent second curve sections, and the second curve section is positioned between adjacent first curve sections, thereby improving the cracking ability of the heater. By positioning the first lead section so as not to overlap with the second section when viewed in the first direction, and positioning the second lead section so as not to overlap with the first section, the high potential section and the low potential section do not overlap between the first wiring and the second wiring when viewed in the first direction. Therefore, in the heater of (6) above, it is difficult for current to leak between the first wiring and the second wiring regardless of the volume resistivity of the gas. The heater of (6) above has superior cracking ability because it is difficult for current to leak between the first wiring and the second wiring, and cracking ability can be improved by the first circuit pattern and the second circuit pattern.

[0023] [Details of embodiments of the present disclosure]

[0024] Specific embodiments of the heater of the present disclosure will be described with reference to the drawings. Identical reference numerals in the drawings represent identical or substantial parts. In each drawing, for convenience of explanation, parts of the configuration may be exaggerated or simplified. The dimensional ratios of each part in the drawings may also differ from the actual parts. Furthermore, the present invention is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0025] <Embodiment 1>

[0026] ≪Overview≫

[0027] With reference to FIGS. 1 to 5, a heater (1) of embodiment 1 is described. As shown in FIG. 1, the heater (1) comprises a gas (2) and a plurality of wires (4) as heating elements. The plurality of wires (4) are arranged inside the gas (2). The plurality of wires (4) comprises a first wire (5) and a second wire (6) arranged at intervals in a first direction (D1) along the thickness of the gas (2). As shown in FIGS. 2 and 3, the first wire (5) comprises a first high potential section (5H) and a first low potential section (5L). As shown in FIGS. 2 and 4, the second wire (6) comprises a second high potential section (6H) and a second low potential section (6L).

[0028] In FIG. 2, the first wiring (5) is shown as a solid line and the second wiring (6) is shown as a dashed line. In FIG. 2 and FIG. 3, hatching is applied to the first high potential section (5H). In FIG. 2 and FIG. 4, hatching is applied to the second high potential section (6H).

[0029] As shown in FIG. 2, the heater (1) has a plurality of wires (4) facing toward a first direction (D1), and has an overlapping area (7) in which the first wire (5) and the second wire (6) overlap. The overlapping area (7) has a first area (71) and a second area (72). The overlapping area (7) may further have at least one of a third area (73) and a fourth area (74). The first area (71) and the second area (72) are mandatory areas, and the third area (73) and the fourth area (74) are optional areas. The overlapping area (7) of the present example has a first area (71), a second area (72), a third area (73), and a fourth area (74), as shown in FIG. 2.

[0030] One of the features of the heater (1) of embodiment 1 is that the average potential difference V between the first wiring (5) and the second wiring (6) in each of the first area (71), the second area (72), the third area (73), and the fourth area (74) is smaller than a specific value.

[0031] Gas

[0032] The body (2) is a disc. As shown in FIG. 1, the body (2) has a first surface (21) and a second surface (22). The first surface (21) and the second surface (22) face each other. On the first surface (21), a heating object, not shown, is placed. The heating object is, for example, a wafer such as a semiconductor. A support member (9) is attached to the second surface (22).

[0033] The material of the gas (2) is, for example, ceramics. The ceramics are, for example, aluminum nitride, silicon nitride, silicon carbide, or aluminum oxide. The gas (2) may be formed from a composite material of the ceramics and a metal. The metal is, for example, aluminum, copper, or an alloy thereof.

[0034] ≪Balance≫

[0035] The wiring (4) is a heating element that heats a heating object placed on the first surface (21) of the gas (2). The wiring (4) comprises a first wiring (5) and a second wiring (6). As shown in FIG. 1, the first wiring (5) and the second wiring (6) are spaced apart in the first direction (D1). As shown in FIG. 2, the first wiring (5) and the second wiring (6) are arranged concentrically with the gas (2). Concentricity here means that when the heater (1) is viewed in a plane in the first direction (D1), the envelope of the first wiring (5) and the envelope of the second wiring (6) have a common center, and the diameters of each envelope are different. The center of this envelope coincides with the center (20) of the gas (2). The first wiring (5) and the second wiring (6) are temperature-controlled independently of each other.

[0036] [1st Wiring]

[0037] The first wiring (5) is positioned in a layer closer to the first surface (21) than the second wiring (6), as shown in FIG. 1. The first wiring (5) is positioned in an area including the center (20) of the gas (2), as shown in FIG. 2.

[0038] As shown in FIG. 3, the first wiring (5) has a first high potential section (5H) and a first low potential section (5L). The first high potential section (5H) is a region where the potential is greater than or equal to half of the applied voltage of the first wiring (5). The first low potential section (5L) is a region where the potential is less than or equal to half of the applied voltage of the first wiring (5). The first high potential section (5H) and the first low potential section (5L) are connected in a single line.

[0039] The first wiring (5) has a first circuit pattern (50) disposed in an area including the center (20) (Fig. 2) of the gas (2). In this example, the first circuit pattern (50) is disposed in a circular area including the center (20). The first circuit pattern (50) is configured, for example, by bending a strip-shaped portion formed by the first wiring (5). The bending of the strip-shaped portion includes bending in a spiral or meandering shape. The first circuit pattern (50) is appropriately selected according to the heating temperature and the required temperature distribution.

[0040] The first circuit pattern (50) of the present example comprises a plurality of curved sections (51) and a plurality of folded sections (52). The plurality of curved sections (51) are each arranged along different circumferences of concentric circles with respect to the body (2). The plurality of folded sections (52) connect adjacent curved sections (51) so that the plurality of curved sections (51) are connected in a single line.

[0041] A plurality of curved sections (51) comprises a plurality of first curved sections (51H) and a plurality of second curved sections (51L). Each first curved section (51H) is formed at a first high potential section (5H). A plurality of first curved sections (51H) are arranged in parallel within the envelope of the first wiring (5), extending from the center of the envelope towards the outer edge. Adjacent first curved sections (51H) are connected by a folded section (52) formed at the first high potential section (5H). A second curved section (51L) is formed at a first low potential section (5L). A plurality of second curved sections (51L) are arranged in parallel within the envelope of the first wiring (5), extending from the center of the envelope towards the outer edge. Adjacent second curved sections (51L) are connected by a folded section (52) formed at the first low potential section (5L). In this example, the boundary between the first curved section (51H) and the second curved section (51L) is on the outermost circumference of the different circumferences of the concentric circles with respect to the body (2).

[0042] In this example, a portion of a plurality of first curve sections (51H) comprises a first section (55H) positioned between adjacent second curve sections (51L). In this example, a portion of a plurality of second curve sections (51L) comprises a second section (55L) positioned between adjacent first curve sections (51H). In FIG. 3, the first section (55H) and the second section (55L) are each enclosed by a two-dot dashed line. In the first circuit pattern (50), the crack resistance of the heater (1) can be improved by providing a first curve section (51H) between adjacent second curve sections (51L) and also providing a second curve section (51L) between adjacent first curve sections (51H). The first section (55H) and the second section (55L) are positioned offset in a direction along the circumference of the envelope circle of the first wiring (5), for example.

[0043] A terminal not shown is connected to each of the first end of the first curved section (51H) and the first end of the second curved section (51L). The connection point (59H) with the terminal in the first curved section (51H) and the connection point (59L) with the terminal in the second curved section (51L) are positioned apart from each other at approximately the center of the body (2).

[0044] [2nd Wiring]

[0045] The second wiring (6) is positioned in a layer further from the first surface (21) than the first wiring (5), as shown in FIG. 1. The second wiring (6) is positioned over a wide range extending from the center (20) of the body (2) to the vicinity of the outer edge, as shown in FIG. 2.

[0046] As shown in FIG. 4, the second wiring (6) is provided with a second high potential section (6H) and a second low potential section (6L). The second high potential section (6H) is a region where the potential is greater than or equal to half of the applied voltage of the second wiring (6). The second low potential section (6L) is a region where the potential is less than or equal to half of the applied voltage of the second wiring (6). The second high potential section (6H) and the second low potential section (6L) are connected in a single line.

[0047] The second wiring (6) comprises a second circuit pattern (60) disposed in an annular area surrounding the first circuit pattern (50). In this example, the second circuit pattern (60) is disposed in an annular area surrounding the first circuit pattern (50). The second circuit pattern (60) is configured, for example, by bending a strip-shaped portion formed by the second wiring (6). The bending of the strip-shaped portion includes bending in a spiral or meandering shape. The shape of the second circuit pattern (60) is appropriately selected according to the heating temperature and the required temperature distribution. By having the first circuit pattern (50) disposed in a circular area including the center (20) of the gas (2) and the second circuit pattern (60) disposed in an annular area surrounding the first circuit pattern (50), the first wiring (5) and the second wiring (6) can be temperature-controlled independently of each other, thereby improving the crack resistance of the heater (1).

[0048] The second circuit pattern (60) of the present example comprises a plurality of curved sections (61) and a plurality of folded sections (62). The plurality of curved sections (61) are each arranged along different circumferences of concentric circles with respect to the body (2). The plurality of folded sections (62) connect adjacent curved sections (61) so that the plurality of curved sections (61) are connected in a single line.

[0049] A plurality of curved sections (61) comprises a plurality of third curved sections (61H) and a plurality of fourth curved sections (61L). Each third curved section (61H) is formed in the second high potential section (6H). A plurality of third curved sections (61H) are arranged in parallel within the envelope of the second wiring (6), extending from the center of the envelope towards the outer edge. Adjacent third curved sections (61H) are connected by a folded section (62) formed in the second high potential section (6H). A fourth curved section (61L) is formed in the second low potential section (6L). A plurality of fourth curved sections (61L) are arranged in parallel within the envelope of the second wiring (6), extending from the center of the envelope towards the outer edge. Adjacent fourth curved sections (61L) are connected by a folded section (62) formed in the second low potential section (6L). In this example, the boundary between the third curve section (61H) and the fourth curve section (61L) is on the outermost circumference of the different circumferences of the concentric circles with respect to the body (2).

[0050] In this example, the third curve section (61H) and the fourth curve section (61L) are arranged symmetrically. That is, in this example, when viewed from a second direction orthogonal to the first direction (D1), the fourth curve section (61L) is not placed between adjacent third curve sections (61H), nor is the third curve section (61H) placed between adjacent fourth curve sections (61L). When viewed from a second direction orthogonal to the first direction (D1), the fourth curve section (61L) may be placed between adjacent third curve sections (61H), and the third curve section (61H) may be placed between adjacent fourth curve sections (61L).

[0051] The second wiring (6) is provided with a first output section (65H) and a second output section (65L). The first output section (65H) is formed at the second high potential section (6H). The first output section (65H) is positioned from the second circuit pattern (60) toward the center of the body (2). A terminal not shown is positioned at the center of the body (2). The first output section (65H) connects the terminal to the first end of the third curve section (61H). The second output section (65L) is formed at the second low potential section (6L). The second output section (65L) is positioned from the second circuit pattern (60) toward the center of the body (2). The second output section (65L) connects the terminal to the first end of the fourth curve section (61L). The connection point (69H) with the terminal in the first output section (65H) and the connection point (69L) with the terminal in the second output section (65L) are arranged apart from each other at approximately the center of the body (2). By arranging the first output section (65H) and the second output section (65L) from the second circuit pattern (60) toward the center (20) of the body (2), the connection points (69H, 69L) with the terminals in the first wiring (5) and the second wiring (6) can be concentrated near the center (20) of the body (2).

[0052] The first outlet (65H) and the second outlet (65L) are formed wide to prevent heat generation. The respective outlines of the first outlet (65H) and the second outlet (65L) correspond, for example, to a semicircle of the envelope of the first wiring (5).

[0053] In this example, the second extraction section (65L) is provided with a notch (68). The notch (68) is opened near the center of the gas (2) in the semicircular contour of the second extraction section (65L) and is formed in a quarter circle. When viewed toward the first direction (D1), a part of the first high potential section (5H) is disposed within the notch (68) (Fig. 2).

[0054] As shown in FIGS. 2 and 5, the heater (1) has an overlapping area (7) in which the first wiring (5) and the second wiring (6) overlap when viewed toward the first direction (D1). The overlapping area (7) of the present example has a first area (71), a second area (72), a third area (73), and a fourth area (74), as shown in FIGS. 2.

[0055] The first region (71) is the region where the first high potential (5H) and the second high potential (6H) overlap. The second region (72) is the region where the first low potential (5L) and the second low potential (6L) overlap. The third region (73) is the region where the first high potential (5H) and the second low potential (6L) overlap. The fourth region (74) is the region where the first low potential (5L) and the second high potential (6H) overlap. In FIG. 5, the first region (71) is shown as a cross-section cut along the first direction (D1). In each of the second region (72), third region (73), and fourth region (74), just like the first region (71) shown in FIG. 5, the first wiring (5) and the second wiring (6) overlap in the cross-section cut along the first direction (D1).

[0056] The overlapping area (7) of the present example is, as shown in FIG. 2, the point where the first outgoing portion (65H) (Fig. 4) and the first high potential portion (5H) overlap when viewed toward the first direction (D1), and the point where the first low potential portion (5L) overlaps with the point other than the notch (68) (Fig. 4) in the second outgoing portion (65L). The overlapping area (7) of the present example is a point corresponding to the strip-shaped portion formed by the first wiring (5).

[0057] The first extraction section (65H) overlaps the first high potential section (5H) and the first low potential section (5L) when viewed toward the first direction (D1). In this example, most of the first extraction section (65H) overlaps the first high potential section (5H). The first region (71) of this example is most of the first high potential section (5H) that overlaps the first extraction section (65H). The first extraction section (65H) of this example overlaps the second section (55L) (Fig. 3), which is part of the first low potential section (5L). The fourth region (74) of this example is a point of the second section (55L) that overlaps the first extraction section (65H).

[0058] Looking toward the first direction (D1), points other than the notch (68) in the second extraction section (65L) overlap with the first low potential section (5L) and the first high potential section (5H). In this example, most of the second extraction section (65L) overlaps with the first low potential section (5L). The second region (72) of this example is most of the first low potential section (5L) that overlaps with the second extraction section (65L). The second extraction section (65L) of this example overlaps with the first section (55H) (Fig. 3), which is part of the first high potential section (5H). The third region (73) of this example is a point of the first section (55H) that overlaps with the second extraction section (65L).

[0059] The average potential difference V between the first wire (5) and the second wire (6) in each of the first region (71), the second region (72), the third region (73), and the fourth region (74) is less than the value calculated by √{(α×ρ×L) / S}. α is a predetermined allowable heat generation amount. The unit of α is W. ρ is the volume resistivity of the gas (2). The unit of ρ is Ω·m. L is the distance between the first wire (5) and the second wire (6) along the first direction (D1). The unit of L is mm. S is the area of ​​each of the first region (71), the second region (72), the third region (73), and the fourth region (74) when viewed toward the first direction (D1). The unit of S is mm².

[0060] In each of the first region (71), second region (72), third region (73), and fourth region (74), if each region (71, 72, 73, 74) is divided into multiple regions by length, the above formula is obtained using the area (S) of each divided region. The number of divided regions in each region (71, 72, 73, 74) depends on the shape of the first circuit pattern (50), the first output section (65H), and the second output section (65L). In this example, the number of divided regions depends on the shape of the first circuit pattern (50). The first region (71) shown in FIG. 2 is divided into five regions. The second region shown in FIG. 2 is also divided into five regions. The third region (73) shown in FIG. 2 is not divided by length and includes a single region. The fourth region (74) shown in Fig. 2 is also not divided by length and includes a single region.

[0061] In each of the first region (71), second region (72), third region (73), and fourth region (74), the average potential difference V between the first wire (5) and the second wire (6) is smaller than the value calculated by √{(α×ρ×L) / S}, so that it is difficult for current to leak between the first wire (5) and the second wire (6). Since it is difficult for current to leak between the first wire (5) and the second wire (6), it is difficult for the temperature of the gas (2) to rise locally.

[0062] The allowable heat output α is, for example, 5 W or less. If the allowable heat output α is 5 W or less, the degree of deterioration of cracks in the gas (2) can be reduced to 2°C or less, for example, as shown in the test example described later. The smaller the allowable heat output α, the better, and it may be 3 W or less. If the allowable heat output α is 3 W or less, for example, the degree of deterioration of cracks in the gas (2) can be reduced to 1°C or less.

[0063] The gap (L) between the first wiring (5) and the second wiring (6) is, for example, 2 mm or more and 20 mm or less. The gap (L) is the distance between the mutually facing surfaces of the layer where the first wiring (5) is placed and the layer where the second wiring (6) is placed. By having a gap (L) of 2 mm or more, it is easy to electrically insulate between the first wiring (5) and the second wiring (6). By having a gap (L) of 20 mm or less, the body (2) does not become excessively thick. The gap (L) may be 2 mm or more and 10 mm or less, or 2 mm or more and 6 mm or less. The thickness of the body (2) is, for example, 10 mm or more and 50 mm or less.

[0064] The material of the wiring (4) is not particularly limited as long as it is a material capable of heating the object to be heated to a desired temperature. The material of the wiring (4) is a known metal suitable for resistance heating. The metal is, for example, stainless steel, nickel, nickel alloy, silver, silver alloy, tungsten, tungsten alloy, molybdenum, molybdenum alloy, chromium, or chromium alloy.

[0065] The wiring (4) can be manufactured, for example, by combining a screen printing method and a hot press bonding method. In the case of the present example, it can be manufactured by the following procedure. Three ceramic substrates and a screen mask capable of transferring the first wiring (5) and the second wiring (6) are prepared. The screen mask used is one capable of producing the first circuit pattern (50) of the first wiring (5), the second circuit pattern (60) of the second wiring (6), the first lead portion (65H), and the second lead portion (65L). On each of the two ceramic substrates, the screen mask of the first circuit pattern (50), the second circuit pattern (60), the first lead portion (65H), and the second lead portion (65L) to be produced is placed. A paste that becomes the wiring (4) is applied to the ceramic substrate on which the screen mask is placed. The wiring (4) is transferred to the ceramic substrate using a squeegee. After transferring the wiring (4), the screen mask is removed. According to the above, a first substrate with the first wiring (5) transferred thereon and a second substrate with the second wiring (6) transferred thereon are obtained. The first substrate, the second substrate, and a ceramic substrate without the wiring transferred thereon are attached in sequence and bonded by hot pressing. By this bonding, a heater (1) is manufactured in which the first wiring (5) and the second wiring (6) are spaced apart in the first direction (D1) inside the body (2).

[0066] <Embodiment 2>

[0067] Referring to FIGS. 6 and 7, the heater (1) of embodiment 2 is described. The heater (1) of embodiment 2 differs from embodiment 1 in the shape of the first outlet (65H) and the second outlet (65L) in the second wiring (6). The first wiring (5) of embodiment 2 has the same shape as embodiment 1 shown in FIG. 3. The first wiring (5) is disposed in a layer closer to the first surface (21) ( FIG. 1) than the second wiring (6), just like in embodiment 1.

[0068] The first outlet (65H) is positioned so as not to overlap with the second outlet (55L) (Fig. 3) when viewed toward the first direction (D1). The second outlet (65L) is positioned so as not to overlap with the first outlet (55H) (Fig. 3) when viewed toward the first direction (D1). In the heater (1) of embodiment 2, the overlapping area (7) includes only two areas: the first area (71) and the second area (72). In the heater (1) of embodiment 2, the overlapping area (7) does not include the third area (73) and the fourth area (74) shown in Fig. 2.

[0069] The first extraction section (65H) is provided with an arc-shaped notch (66) as shown in FIG. 7. The notch (66) is opened in the middle of the chord forming the semicircular outline of the first extraction section (65H) and is formed in an arc shape extending over a range of 90°. Looking toward the first direction (D1), the second section (55L) is positioned within the notch (66) (Fig. 6). Looking toward the first direction (D1), the first high potential section (5H) overlaps at a point other than the notch (66) in the first extraction section (65H). The first region (71) is the majority of the first high potential section (5H) that overlaps at a point other than the notch (66) in the first extraction section (65H).

[0070] The second outlet (65L) is provided with two notches (67, 68) as shown in FIG. 7. The notch (67) is opened in the middle of the string forming the semicircular outline of the second outlet (65L) and is formed in an arc shape over a range of 90°. The notch (68) is identical to the notch (68) of Embodiment 1. When viewed toward the first direction (D1), the first part (55H) is positioned within the notch (67) (Fig. 2). When viewed toward the first direction (D1), the first low-potential part (5L) overlaps at a point other than the notches (67, 68) in the second outlet (65L). The second region (72) is most of the first low-potential section (5L) that overlaps at points other than the notches (67, 68) in the second extraction section (65L).

[0071] If a first part (55H) and a second part (55L) are provided in the first wiring (5), the cracking ability of the heater (1) can be improved, but when viewed toward the first direction (D1), the first high potential part (5H) and the second low potential part (6L) are likely to overlap, and the first low potential part (5L) and the second high potential part (6H) are likely to overlap. By providing a notch (66) in the first outgoing part (65H) and providing notches (67, 68) in the second outgoing part (65L), when viewed toward the first direction (D1), the first high potential part (5H) and the second low potential part (6L) do not overlap, and the first low potential part (5L) and the second high potential part (6H) do not overlap. Therefore, regardless of the volume resistivity of the gas (2), it is difficult for current to leak between the first wiring (5) and the second wiring (6). Because it is difficult for current to leak between the first wiring (5) and the second wiring (6), it is difficult for the temperature of the gas (2) to rise locally.

[0072] [Test Example]

[0073] In the test example, a plurality of heaters were fabricated in which the first wiring and the second wiring were spaced apart in a first direction along the thickness of the gas and placed inside the gas, and the heat output of each heater and the degree of crack deterioration were investigated.

[0074] Seven test specimens, from A to G, were manufactured. Each test specimen is equipped with a first wiring (5) as shown in FIG. 3 and a second wiring (6) as shown in FIG. 4. In each test specimen, when viewed toward the first direction (D1), the first wiring (5) and the second wiring (6) overlap as shown in FIG. 2. The first wiring (5) is equipped with a first high potential section (5H) and a first low potential section (5L). The second wiring (6) is equipped with a second high potential section (6H) and a second low potential section (6L). In each test specimen, when viewed toward the first direction (D1), the first wiring (5) and the second wiring (6) overlap in an overlapping area (7), and the first area (71), the second area (72), the third area (73), and the fourth area (74) are provided.

[0075] Heater's heat output

[0076] For the heater of each test specimen, the amount of heat generated was calculated with an AC power source in phase connected. The amount of heat generated is (V 2 It was calculated as ×S) / (ρ×L). For each test specimen, the points where heat can be generated are the third region (73) and the fourth region (74) among the overlapping regions (7). The first region (71) and the second region (72) are difficult to generate heat because the high potential parts or the low potential parts overlap. The third region (73) and the fourth region (74) are easy to generate heat because the high potential and the low potential parts overlap. The third region (73) and the fourth region (74) have the same current conditions and area. Therefore, in this example, the amount of heat generated in the fourth region (74) was calculated. In the above formula, V is the average potential difference between the first wiring (5) and the second wiring (6) in the fourth region (74). S is the area of ​​the fourth region (74) when viewed toward the first direction. ρ is the volume resistivity of the gas (2). L is the interval along the first direction (D1) of the first wiring (5) and the second wiring (6). The unit of heat generation is W.

[0077] The average potential difference V in the fourth region (74) of test specimens A, B, and C was 205 V. The average potential difference V in the fourth region (74) of test specimens D, E, F, and G was 181 V. The average potential difference V was calculated as follows. In the fourth region (74) of test specimen A, the region of the first low potential section (5L) between 0 V and 10 V overlapped with the region of the second high potential section (6H) between 200 V and 220 V. In the fourth region (74), the average potential of the first low potential section (5L) was 5 V, and the average potential of the second high potential section (6H) was 210 V. Therefore, the average potential difference V in the fourth region (74) of test specimen A is 205 V. The average potential difference V of the fourth region (74) of another test specimen was also calculated in the same way.

[0078] The area S of the fourth region (74) of test specimens A, B, and C was 101.7 mm². The area S of the fourth region (74) of test specimen D was 99.9 mm². The area S of the fourth region (74) of test specimens E, F, and G was 128.6 mm².

[0079] The volume resistivity ρ of the gas (2) of test specimens A and E was 10,000 Ω·cm. The volume resistivity ρ of the gas (2) of test specimens B and F was 50,000 Ω·cm. The volume resistivity ρ of the gas (2) of test specimens C and G was 100,000 Ω·cm. The volume resistivity ρ of the gas (2) of test specimen D was 5,000 Ω·cm.

[0080] In any test specimen, the gap (L) between the first wiring (5) and the second wiring (6) was 4 mm.

[0081] <Degree of Worsening Cracks in the Heater>

[0082] For each test specimen's heater, the degree of crack deterioration was measured using an infrared camera. The degree of crack deterioration is the temperature deviation on the surface of the gas (2) of each test specimen, and is the difference between the lowest temperature and the highest temperature. The unit of the degree of crack deterioration is °C.

[0083] Figure 8 shows the relationship between the amount of heat generated and the degree of crack deterioration for the heater of each test specimen. In the graph of Figure 8, the horizontal axis represents the amount of heat generated, and the vertical axis represents the degree of crack deterioration. From the graph of Figure 8, it can be seen that the degree of crack deterioration and the amount of heat generated satisfy the following relationship. In the following relationship, the degree of crack deterioration is denoted as y, and the amount of heat generated is denoted as x.

[0084] y=0.01194x 2 +0.3245x

[0085] In the graph of Fig. 8, the above relationship is represented by a solid line. In the above relationship, as for the performance of the heater, for example, if the heat output is 5 W or less, the degree of crack deterioration can be reduced to 2°C or less. Also, if the heat output is 3 W or less, the degree of crack deterioration can be reduced to 1°C or less.

[0086] As shown in FIG. 8, test specimens B, C, F, and G satisfy the condition that the heat generation is 5 W or less and the degree of crack deterioration is 2° or less. All test specimens satisfying the condition that the heat generation is 5 W or less and the degree of crack deterioration is 2° or less have an average potential difference V between the first wiring and the second wiring in the overlapping region that is smaller than the value calculated by √{(5×ρ×L) / S}. In other words, by having an average potential difference (V) between the first wiring and the second wiring in the overlapping region that is smaller than the value calculated by √{(5×ρ×L) / S}, the condition that the heat generation is 5 W or less and the degree of crack deterioration is 2° or less can be satisfied. Explanation of the symbols

[0087] 1: Heater 2: Aircraft 20: Center 21: Page 1 22: Page 2 4: Wiring 5: First wiring 5H: First high potential section 5L: 1st low potential section 50: First circuit pattern 51: Curved section 51H: 1st curve section 51L: 2nd curve section 52: Fold 55H: Part 1 55L: Part 2 59H, 59L: Connection points 6: Second wiring 6H: Second high potential 6L: Second low-potential section 60: Second circuit pattern 61: Curved section 61H: Third curve section 61L: 4th curve section 62: Fold 65H: 1st Outlet 65L: Second outlet 66, 67, 68: Notch 69H, 69L: Connection points 7: Overlapping area 71: First Zone 72: Second Zone 73: The Third Zone 74: The Fourth Zone 9: Lack of support L: Interval S: Area D1: First direction

Claims

Claim 1 A heater comprises a disc-shaped body and a plurality of wires as heating elements disposed inside the body, wherein the plurality of wires comprises a first wire and a second wire arranged at a distance in a first direction along the thickness of the body, wherein the first wire comprises a first high potential and a first low potential, and the second wire comprises a second high potential and a second low potential, wherein, when viewed toward the first direction, the plurality of wires have an overlapping region in which the first wire and the second wire overlap, wherein the overlapping region comprises a first region and a second region, wherein the first region is an region in which the first high potential and the second high potential overlap, and the second region is an region in which the first low potential and the second low potential overlap, and wherein the average potential difference V between the first wire and the second wire in each of the first region and the second region is smaller than the value obtained by √{(α×ρ×L) / S1}. [α is pre- It is a defined allowable heat output, and the unit is W. ρ is the volume resistivity of the gas, and the unit is Ω·m. L is the distance between the first wiring and the second wiring along the first direction, and the unit is mm. S1 is the respective area of ​​the first region and the second region when viewed toward the first direction, and the unit is mm². Claim 2 A heater according to claim 1, wherein the overlapping region comprises two regions, the first region and the second region. Claim 3 A heater according to claim 1, wherein the overlapping region comprises at least one of a third region and a fourth region, wherein the third region is an area where the first high potential part and the second low potential part overlap, and the fourth region is an area where the first low potential part and the second high potential part overlap, and wherein the average potential difference V between the first wiring and the second wiring in each of the third region and the fourth region is smaller than the value obtained by √{(α×ρ×L) / S2}. [S2 is the area of ​​each of the third region and the fourth region when viewed toward the first direction, and the unit is mm².] Claim 4 A heater according to claim 1 or 3, wherein the allowable heat output α is 5 W or less. Claim 5 A heater according to claim 2 or 3, wherein the first wiring comprises a first circuit pattern disposed in an area including the center of the gas, and the second wiring comprises a second circuit pattern disposed in an annular area surrounding the first circuit pattern, and a first and second outlet disposed from the second circuit pattern toward the center of the gas. Claim 6 In claim 2 or 3, the first wiring comprises a first circuit pattern disposed in an area including the center of the body, and the first circuit pattern comprises a plurality of curved sections each disposed along different circumferences concentric with the body, and a plurality of folded sections connecting adjacent curved sections so that the plurality of curved sections are connected in a single line, wherein the plurality of curved sections comprises a plurality of first curved sections formed at the first high potential section and a plurality of second curved sections formed at the first low potential section, wherein a part of the plurality of first curved sections comprises a first section disposed between adjacent second curved sections, and a part of the plurality of second curved sections comprises a second section disposed between adjacent first curved sections, and wherein the second wiring comprises a second circuit pattern disposed in an annular area surrounding the first circuit pattern, a first lead section formed at the second high potential section, and a second lead section formed at the second low potential section, wherein the first lead section is such that it does not overlap with the second section when viewed toward the first direction A heater arranged toward the center of the gas from the second circuit pattern, wherein the second lead portion is arranged toward the center of the gas from the second circuit pattern so as not to overlap with the first portion when viewed toward the first direction.

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