Heater

Abstract

A heater according to the present disclosure comprises a ceramic substrate, a heating resistor, and a terminal portion. The ceramic substrate has a first surface and a second surface that is positioned on the opposite side from the first surface. The heating resistor is positioned on one end side of the interior of the ceramic substrate. The terminal portion is positioned on the other end side of the ceramic substrate. The first surface is provided with a recess between the heating resistor and the terminal portion.

Description

heater

[0001] The present disclosure relates to a heater.

[0002] 2. Description of the Related Art Conventionally, a ceramic heater having a heat generating portion and a terminal portion inside a ceramic body is known (see Patent Document 1).

[0003] JP 2000-271783 A JP 2000-133419 A

[0004] A heater according to one aspect of the present disclosure includes a ceramic substrate, a heating resistor, and a terminal portion. The ceramic substrate has a first surface and a second surface opposite to the first surface. The heating resistor is located at one end of the interior of the ceramic substrate. The terminal portion is located at the other end of the ceramic substrate. The first surface includes a recess between the heating resistor and the terminal portion.

[0005] FIG. 1 is a perspective view showing an example of a heater according to the first embodiment. FIG. 2 is a plan view showing an example of a heater according to the first embodiment. FIG. 3 is a perspective view showing another example of a heater according to the first embodiment. FIG. 4 is a plan view showing another example of a heater according to the first embodiment. FIG. 5 is a cross-sectional view showing an example of a recess according to the first embodiment. FIG. 6 is a perspective view showing an example of a heater according to a second embodiment. FIG. 7 is a schematic enlarged view of region V shown in FIG. 6. FIG. 8 is a perspective view showing another example of a heater according to the second embodiment. FIG. 9 is a perspective view showing an example of a heater according to the third embodiment. FIG. 10 is a plan cross-sectional view showing an example of a heater according to the fourth embodiment. FIG. 11 is a side cross-sectional view showing an example of a heater according to the fourth embodiment. FIG. 12 is a perspective view showing an example of a heater according to a fifth embodiment. FIG. 13 is a plan view showing an example of a heater according to the fifth embodiment.

[0006] Hereinafter, a heater according to the present disclosure (hereinafter referred to as an "embodiment") will be described in detail with reference to the drawings. Note that the present disclosure is not limited to the embodiment. Furthermore, the embodiments can be appropriately combined within the scope of not causing any contradiction in the processing content. Furthermore, the same components in the following embodiments are given the same reference numerals, and redundant explanations will be omitted.

[0007] Furthermore, in the following embodiments, expressions such as "constant," "orthogonal," "perpendicular," or "parallel" may be used, but these expressions do not necessarily mean "constant," "orthogonal," "perpendicular," or "parallel" in the strict sense. In other words, the above expressions allow for deviations due to, for example, manufacturing precision, installation precision, etc.

[0008] In the drawings referred to below, for ease of understanding, the X-axis, Y-axis, and Z-axis directions are defined as being orthogonal to each other, and an orthogonal coordinate system is shown in which the positive Z-axis direction is the vertically upward direction. The rotation direction around the vertical axis is also referred to as the θ direction.

[0009] In recent years, as devices equipped with heaters have become smaller, there has been a demand for smaller heaters. However, when heaters are made smaller, the distance between the heat-generating part of the heater and the terminal part becomes shorter, which makes it easier for heat to be transferred from the heat-generating part to the terminal part, and there is a risk that the terminal part will be affected by the heat and deteriorate prematurely.

[0010] Therefore, there is a need for a technology that can reduce the deterioration of the terminal portion and improve the durability of the heater.

[0011] First Embodiment First, a heater according to a first embodiment will be described with reference to Fig. 1 and Fig. 2. Fig. 1 is a perspective view showing an example of a heater 1 according to the first embodiment. Fig. 2 is a plan view showing an example of a heater 1 according to the first embodiment.

[0012] As shown in FIGS. 1 and 2, the heater 1 according to the first embodiment includes a ceramic substrate 10, a heating resistor 20, terminal portions 30, conductive portions 40, and lead wires 50.

[0013] The ceramic substrate 10 is, for example, a flat-plate-shaped member having a first surface 10a as one main surface, a second surface 10b located on the opposite side of the first surface 10a, and four side surfaces 10c to 10f connecting the first surface 10a and the second surface 10b. The pair of side surfaces 10c and 10d are side surfaces along the longitudinal direction (X-axis direction) of the ceramic substrate 10. The pair of side surfaces 10c and 10d are examples of third and fourth surfaces that are connected to the first surface 10a and located opposite each other. The pair of side surfaces 10e and 10f are side surfaces that are perpendicular to the longitudinal direction of the ceramic substrate 10, with the side surface 10e located at one end of the ceramic substrate 10 in the longitudinal direction. The side surface 10f is located at the other end of the ceramic substrate 10 in the longitudinal direction.

[0014] The material of the ceramic substrate 10 is, for example, an insulating ceramic. This makes it possible to provide a heater 1 that is highly reliable during rapid temperature rise. The material of the ceramic substrate 10 can be, for example, oxide ceramics, nitride ceramics, or carbide ceramics. Specifically, alumina ceramics, silicon nitride ceramics, aluminum nitride ceramics, silicon carbide ceramics, etc. can be used.

[0015] The ceramic substrate 10 also has a recess 15. The recess 15 is located on the first surface 10a of the ceramic substrate 10. The recess 15 will be described in detail later.

[0016] The heating resistor 20 is located inside the ceramic substrate 10. The heating resistor 20 is located on one end side inside the ceramic substrate 10 and is connected to a first conductive portion 41 and a second conductive portion 42, which will be described later. Note that the one end side here may be, for example, a region including a side surface 10e of two regions obtained by dividing the ceramic substrate 10 into two equal parts in the longitudinal direction of the ceramic substrate 10. The other end side may be, for example, a region including a side surface 10f of two regions obtained by dividing the ceramic substrate 10 into two equal parts in the longitudinal direction of the ceramic substrate 10.

[0017] The heating resistor 20 is a member that generates heat when a current flows through it. The heating resistor 20 may include a high-resistance conductor such as tungsten or molybdenum. When the ceramic substrate 10 is made of silicon nitride ceramic, tungsten carbide is an excellent material for the heating resistor 20 because it has a small difference in thermal expansion coefficient from the ceramic substrate 10 and high heat resistance. The heating resistor 20 is not limited to a shape with folded portions as shown in FIG. 2 and can be modified as appropriate depending on the heating characteristics required of the heater 1, for example.

[0018] The terminal portion 30 is located on the other end side of the ceramic substrate 10. Specifically, the terminal portion 30 is a planar member located on the surface of the other end side of the ceramic substrate 10 and is electrically connected to the heating resistor 20 via the conductive portion 40. The terminal portion 30 is, for example, a metallized layer. The terminal portion 30 as a metallized layer is primarily composed of one or more of gold, nickel, copper, silver, and palladium, and is not subject to deterioration due to oxidation even when used at high temperatures of 400°C or higher. For example, in consideration of preventing migration under conditions involving the passage of a DC power source, the metallized layer is optimally made of a gold-nickel alloy containing 50 to 99% by weight of gold and 1 to 50% by weight of nickel.

[0019] Furthermore, the terminal portion 30 serving as the metallized layer preferably contains, as an active metal, one or more of the elements of Group 4a of the periodic table, namely titanium, vanadium, manganese, cobalt, nickel, and copper, or molybdenum, silicon, zirconium, and hafnium. In particular, from the viewpoints of providing good wettability to the ceramic substrate 10 and not deteriorating the strength of the ceramic substrate 10, it is optimal to contain one or more of vanadium and molybdenum as the active metal, and such active metal may be contained in the form of a nitride, carbide, hydroxide, or the like.

[0020] The terminal portion 30 has a first terminal portion 30a and a second terminal portion 30b. The first terminal portion 30a electrically connects a first conductive portion 41 (described later) to a first lead wire 50a. The second terminal portion 30b electrically connects a second conductive portion 42 (described later) to a second lead wire 50b. The positions of the first terminal portion 30a and the second terminal portion 30b will be described in detail below.

[0021] The conductive portion 40 is located inside the ceramic substrate 10 and is electrically connected to the heating resistor 20. The conductive portion 40 has a first conductive portion 41 and a second conductive portion 42. The first conductive portion 41 extends from the first terminal 30a toward one end of the ceramic substrate 10 in the longitudinal direction (X-axis direction) of the ceramic substrate 10 and is connected to a first end portion, which is one end of the heating resistor 20. That is, the first conductive portion 41 connects the first terminal 30a to the first end portion. The second conductive portion 42 extends from the second terminal 30b toward one end of the ceramic substrate 10 in the longitudinal direction (X-axis direction) of the ceramic substrate 10 and is connected to a second end portion, which is the other end of the heating resistor 20. That is, the second conductive portion 42 connects the second terminal 30b to the second end portion.

[0022] The conductive portion 40 is formed, for example, using the same material as the heating resistor 20. The conductive portion 40 has a lower resistance value per unit length by making the cross-sectional area larger than that of the heating resistor 20 or by making the content of the material forming the ceramic substrate 10 less than that of the heating resistor 20. Note that the conductive portion 40 may be formed using a material different from that of the heating resistor 20.

[0023] The lead wire 50 is located outside the ceramic substrate 10. One end of the lead wire 50 is connected to an external power supply, and the other end is electrically connected to the conductive portion 40 via the terminal portion 30. Power supplied from the external power supply is supplied to the heating resistor 20 via the lead wire 50, the terminal portion 30, and the conductive portion 40. The lead wire 50 is a wire containing a metal material such as nickel, iron, or a nickel-based heat-resistant alloy. The cross section of the lead wire 50 may be, for example, circular, elliptical, or rectangular. The outer diameter of the lead wire 50 may be, for example, 0.5 to 2.0 mm. The lead wire 50 includes a first lead wire 50a and a second lead wire 50b. One of the first lead wire 50a and the second lead wire 50b is an anode lead wire, and the other is a cathode lead wire. The positions of the first lead wire 50a and the second lead wire 50b will be described in detail below.

[0024] In the heater 1 configured as described above, if the ceramic substrate 10 is miniaturized, heat is more likely to be transferred from the heating resistor 20 to the terminal portions 30, and the terminal portions 30 may be affected by the heat and deteriorate prematurely. In particular, if the heating resistor 20 has a shape with folded portions as shown in Fig. 2, the first surface 10a and the second surface 10b, which are the main surfaces of the ceramic substrate 10, have better heat transfer efficiency than the side surfaces 10c to 10f, and therefore heat is more likely to be transferred from the heating resistor 20 to the terminal portions 30.

[0025] 1 and 2, the first surface 10a of the ceramic substrate 10 in the heater 1 according to the first embodiment is configured to have a recess 15 between the heating resistor 20 and the terminal 30. This increases the surface area of ​​the first surface 10a, thereby lengthening the heat path from the heating resistor 20 to the terminal 30. This reduces the transfer of heat from the heating resistor 20 to the terminal 30, thereby reducing deterioration of the terminal 30. As a result, the durability of the heater 1 can be improved.

[0026] 3 and 4 are also possible examples of the heater 1 according to the first embodiment. FIG. 3 is a perspective view showing another example of the heater 1 according to the first embodiment. FIG. 4 is a plan view showing another example of the heater 1 according to the first embodiment. As shown in FIGS. 3 and 4 , the recess 16 between the heating resistor 20 and the terminal 30 may be partially positioned across the direction (Y-axis direction) perpendicular to the longitudinal direction of the ceramic substrate 10. Even in this case, as described above, the surface area of ​​the first surface 10a can be increased, thereby lengthening the heat path from the heating resistor 20 to the terminal 30. This reduces the transfer of heat from the heating resistor 20 to the terminal 30, thereby reducing deterioration of the terminal 30. As a result, the durability of the heater 1 can be improved.

[0027] 3 and 4 have a rectangular shape in plan view, but this is not limiting. For example, the recess 16 may have a circular or elliptical shape, and the heater 1 may have a plurality of recesses 16 of the above shapes.

[0028] Hereinafter, details of the recess 15 of the ceramic substrate 10 according to the first embodiment will be described with further reference to Fig. 5. Fig. 5 is a cross-sectional view showing an example of the recess 15 according to the first embodiment.

[0029] The recess 15 may overlap at least a portion of the first conductive portion 41 and at least a portion of the second conductive portion 42 in a planar perspective view. Specifically, the recess 15 may overlap a portion of the first conductive portion 41 that is closer to the connection with the first terminal 30a than to the connection with the heating resistor 20. Similarly, the recess 15 may overlap a portion of the second conductive portion 42 that is closer to the connection with the second terminal 30b than to the connection with the heating resistor 20. In this manner, the rate of heat transfer (thermal conduction) within the ceramic substrate 10 from the heating resistor 20 to the terminal 30 along the conductive portion 40 is limited by the abrupt decrease in the cross-sectional area of ​​the ceramic substrate 10 at the position of the recess 15. Furthermore, the short distance to the surface of the first face 10a due to the recess 15 facilitates heat dissipation from the ceramic substrate 10. Furthermore, the abrupt increase in the cross-sectional area of ​​the ceramic substrate 10 on the rear end side, which has a lower temperature than the recess 15, reduces heat transfer to the terminal 30.

[0030] Furthermore, the recess 15 may be located across one of the two side surfaces 10c, 10d along the longitudinal direction (X-axis direction) of the ceramic substrate 10. This allows the surface area of ​​the recess 15 to be larger than when the recess 15 is located partially on the first surface 10a, thereby extending the heat path from the heating resistor 20 to the terminal portion 30. This reduces the transfer of heat to the terminal portion 30, improving the durability of the heater 1. Note that the recess 15 need only be located between the heating resistor 20 and the terminal portion 30, and does not necessarily have to be located across one of the two side surfaces 10c, 10d.

[0031] Alternatively, the recess 15 may extend linearly in a direction (Y-axis direction) perpendicular to the longitudinal direction of the ceramic substrate 10. This reduces the variation in heat transfer from the heating resistor 20 of the heater 1 and reduces stress concentration on the terminal portion 30 due to differences in thermal expansion, compared to when the recess 15 extends in a curved line. As a result, deterioration of the terminal portion 30 when the heater 1 is heated or cooled can be reduced, and the durability of the heater 1 can be improved.

[0032] Furthermore, the depth of the recess 15 may be constant in the extending direction of the recess 15, i.e., in the direction (Y-axis direction) perpendicular to the longitudinal direction of the ceramic substrate 10. This allows the thermal conductivity of the recess 15 of the ceramic substrate 10 to be constant throughout the entire recess 15, thereby reducing stress concentration in a part of the recess 15. For example, when the depth of the recess 15 is Da and the thickness of the ceramic substrate 10 is Db, Da may be smaller than Db / 2. However, the depth of the recess 15 is not limited to this.

[0033] As shown in FIG. 5 , the recess 15 has a bottom surface 15 a and two side surfaces 15 b and 15 c that intersect with the longitudinal direction (X-axis direction) of the ceramic substrate 10. This allows the surface area of ​​the recess 15 to be larger than when the cross-sectional shape of the recess 15 is, for example, V-shaped, thereby extending the heat path from the heating resistor 20 to the terminal 30. This reduces heat transfer to the terminal 30, improving the durability of the heater 1. It also makes it less susceptible to cracks due to mechanical stress. Note that the recess 15 does not necessarily need to have the bottom surface 15 a and two side surfaces 15 b and 15 c. For example, the recess 15 may be V-shaped or U-shaped, with its width narrowing downward (in the Z-axis direction).

[0034] 2, the two side surfaces 10c and 10d may extend parallel to each other, which allows the thermal conductivity of the recess 15 of the ceramic substrate 10 to be constant throughout the entire recess 15, thereby reducing stress concentration in a part of the recess 15.

[0035] 2 shows an example in which the two side surfaces 10c, 10d extend linearly in a direction perpendicular to the longitudinal direction of the ceramic substrate 10, but is not limited to this. For example, even if the two side surfaces 10c, 10d extend obliquely with respect to the direction perpendicular to the longitudinal direction of the ceramic substrate 10, it is sufficient that the side surfaces 10c, 10d extend parallel to each other.

[0036] 1 and 2 , the terminals 30 may be located on side surfaces 10c and 10d along the longitudinal direction (X-axis direction) of the ceramic substrate 10. Specifically, the first terminal 30a is located on the side surface 10c on the other end side of the ceramic substrate 10. Similarly, the second terminal 30b is located on the side surface 10d on the other end side of the ceramic substrate 10.

[0037] In this case, the first lead wire 50a is fixed to the side surface 10c on which the first terminal 30a is located. Specifically, the first lead wire 50a is electrically connected to the first terminal 30a and extends from the first terminal 30a outward in the longitudinal direction of the ceramic substrate 10 (positive direction of the X-axis). The second lead wire 50b is fixed to the side surface 10d on which the second terminal 30b is located. Specifically, the second lead wire 50b is electrically connected to the second terminal 30b and extends from the second terminal 30b outward in the longitudinal direction of the ceramic substrate 10 (positive direction of the X-axis). The first lead wire 50a and the second lead wire 50b may be fixed to the side surfaces 10c, 10d of the ceramic substrate 10 using a bonding material (not shown).

[0038] By positioning the terminal portion 30 on the side surfaces 10c and 10d in this manner, heat is less likely to be transferred from the heating resistor 20 to the terminal portion 30 compared to when the terminal portion 30 is positioned on the first surface 10a and the second surface 10b, thereby reducing deterioration of the terminal portion 30.

[0039] As described above, the first surface 10a of the ceramic substrate 10 in the heater 1 according to the first embodiment has a recess 15 between the heating resistor 20 and the terminal 30. This increases the surface area of ​​the first surface 10a, thereby lengthening the heat path from the heating resistor 20 to the terminal 30. This reduces the transfer of heat from the heating resistor 20 to the terminal 30, thereby reducing deterioration of the terminal 30. As a result, the durability of the heater 1 can be improved.

[0040] Although an example in which the recesses 15 are provided on the first surface 10a of the ceramic substrate 10 has been described here, the recesses 15 may also be provided on the second surface 10b.

[0041] Second Embodiment Fig. 6 is a perspective view showing an example of a heater 1 according to a second embodiment. Fig. 7 is a schematic enlarged view of an area V shown in Fig. 6. Fig. 8 is a perspective view showing another example of the heater 1 according to the second embodiment.

[0042] A coating material containing a plurality of boron nitride particles may be applied to at least a portion of a region of first surface 10a of ceramic substrate 10 excluding recesses 15. For example, as shown in Fig. 6 , a coating material containing a plurality of boron nitride particles may be applied to region R1 of first surface 10a excluding recesses 15.

[0043] 7, at least some of the boron nitride particles B contained in the coating material applied to the first surface 10a are located apart from other boron nitride particles B. In other words, the boron nitride particles B are sparsely dispersed in the region R1. That is, the coating material is not applied solidly in the region R1, and the first surface 10a of the ceramic substrate 10 is exposed.

[0044] In this way, the thermal conductivity of first surface 10a can be improved by applying a coating material containing a plurality of boron nitride particles to first surface 10a of ceramic substrate 10. On the other hand, as described above, the coating material containing a plurality of boron nitride particles is not applied to recesses 15, so the thermal conductivity of recesses 15 can be reduced, making it more difficult for heat to be transferred from heating resistor 20 to terminal portion 30, and reducing deterioration of terminal portion 30.

[0045] Furthermore, since heat tends to concentrate on each boron nitride particle B, by positioning the boron nitride particles in a spaced-apart relationship as described above, stress concentration between the boron nitride particles B can be reduced, thereby improving the durability of the heater 1.

[0046] The region to which the coating material is applied is not limited to the above example. For example, as shown in Fig. 8, a coating material containing a plurality of boron nitride particles may be applied to a region R2 of the first surface 10a other than the region closer to the side surface 10f than the recess 15. This makes it more difficult for heat to be transferred from the heating resistor 20 to the terminal portion 30, thereby reducing deterioration of the terminal portion 30.

[0047] The second surface 10b of the ceramic substrate 10 may also be coated with a coating material containing a plurality of boron nitride particles.

[0048] 9 is a perspective view showing an example of a heater 1 according to a third embodiment. In the first embodiment, an example in which the recess 15 is provided on only one of the two main surfaces of the ceramic substrate 10 has been described, but the present invention is not limited to this, and the ceramic substrate 10 may have a plurality of recesses.

[0049] For example, as shown in Fig. 9, the ceramic substrate 10 may have a first recess 15d located on the first surface 10a and a second recess 15e located on the second surface 10b. In this case, similar to the recess 15 according to the first embodiment, the first recess 15d and the second recess 15e are located on the first surface 10a and the second surface 10b, respectively, between the heating resistor 20 (see Fig. 2) and the terminal portion 30. The first recess 15d and the second recess 15e may also be located across one of the two side surfaces 10c, 10d along the longitudinal direction (X-axis direction) of the ceramic substrate 10. The first recess 15d and the second recess 15e may each have a bottom surface and two side surfaces perpendicular to the longitudinal direction (X-axis direction) of the ceramic substrate 10.

[0050] In this way, by providing the first recess 15d and the second recess 15e on the first surface 10a and the second surface 10b, which are the two main surfaces of the ceramic substrate 10, respectively, the heat path on the first surface 10a and the second surface 10b can be lengthened, thereby reducing the transfer of heat from the heating resistor 20 to the terminal portion 30 and reducing deterioration of the terminal portion 30. Therefore, the durability of the heater 1 can be improved.

[0051] Although the first recess 15d and the second recess 15e each have a shape including a bottom surface and two side surfaces, this is not a limitation. For example, the first recess 15d and the second recess 15e may have a V-shape or a U-shape that narrows downward (in the Z-axis downward direction). Furthermore, the first recess 15d and the second recess 15e do not necessarily have to have the same shape and may have different shapes.

[0052] Fourth Embodiment Fig. 10 is a plan cross-sectional view showing an example of a heater 1 according to a fourth embodiment. Fig. 11 is a side cross-sectional view showing an example of a heater 1 according to the fourth embodiment.

[0053] The heater 1 may further include a cylindrical member 60 that holds the ceramic substrate 10. The cylindrical member 60 has a cylindrical shape that surrounds the circumferential surface of the ceramic substrate 10. A portion of the ceramic substrate 10 is inserted into the cylindrical member 60. The cylindrical member 60 is positioned apart from the ceramic substrate 10 and is bonded to the ceramic substrate 10 by a bonding material 70.

[0054] For example, a ceramic insulator can be used as the cylindrical member 60. For example, an inorganic adhesive can be used as the bonding material 70.

[0055] In the heater 1 configured as described above, the recess 15 of the ceramic substrate 10 may be located between the heating resistor 20 and the cylindrical member 60. In other words, the recess 15 of the ceramic substrate 10 is located in a portion that is not inserted into the cylindrical member 60. This allows the heat path from the heating resistor 20 to the cylindrical member 60 to be extended, making it difficult for heat to be transmitted to the bonding material 70, and making it difficult for the bonding material 70 to thermally expand. This allows for a reduction in the stress applied to the ceramic substrate 10.

[0056] Fifth Embodiment Fig. 12 is a perspective view showing an example of a heater 1 according to a fifth embodiment. Fig. 13 is a plan view showing an example of a heater 1 according to the fifth embodiment.

[0057] The first surface 10a of the heater 1 may have a protrusion 80 located between the heating resistor 20 and the terminal 30. Similar to the recess 15 of the heater 1 according to the first embodiment, the protrusion 80 may overlap at least a part of the first conductive portion 41 and at least a part of the second conductive portion 42. Specifically, the protrusion 80 may overlap a portion of the first conductive portion 41 that is closer to the connection with the terminal 30 than to the connection with the heating resistor 20.

[0058] By providing the protrusions 80 on the first surface 10a of the heater 1 in this manner, the surface area of ​​the first surface 10a can be increased, thereby lengthening the heat path from the heating resistor 20 to the terminal portion 30. As a result, the transfer of heat from the heating resistor 20 to the terminal portion 30 can be reduced, and the durability of the heater 1 can be improved.

[0059] Furthermore, the protrusions 80 may be integral with the ceramic substrate 10. If the protrusions 80 and the ceramic substrate 10 are separate bodies and the protrusions 80 are provided on the ceramic substrate 10 via a bonding material, repeated use of the heater 1 may cause stress to concentrate between the ceramic substrate 10 and the protrusions 80 during thermal expansion, which may cause cracks and lead to separation of the bond. Therefore, by integrating the protrusions 80 with the ceramic substrate 10 as described above, cracks are less likely to occur, and the durability of the heater 1 can be improved.

[0060] Other Embodiments In the above-described embodiment, the lead wires 50 are connected to an external power source and used as a heater that generates heat by passing a current through the heating resistor 20, but this is not limited to this. For example, a resistance meter may be connected to the lead wires 50 to use as a temperature sensor. In this case, as in the case of a heater, by providing the recesses 15 on the first surface 10a, which is the main surface of the ceramic substrate 10, the surface area of ​​the first surface 10a can be increased, thereby extending the heat path and improving the heat resistance of the temperature sensor.

[0061] In one embodiment, (1) a heater (for example, heater 1) includes a ceramic substrate (for example, ceramic substrate 10), a heating resistor (for example, heating resistor 20), and a terminal portion (for example, terminal portion 30). The ceramic substrate has a first surface (for example, first surface 10a) and a second surface (for example, second surface 10b) located on the opposite side of the first surface. The heating resistor is located on one end side inside the ceramic substrate. The terminal portion is located on the other end side of the ceramic substrate. The first surface includes a recess (for example, recess 15) between the heating resistor and the terminal portion.

[0062] (2) In the heater of (1) above, the heating resistor has a first end and a second end, the terminal portion has a first terminal portion (for example, first terminal portion 30a) and a second terminal portion (for example, second terminal portion 30b), a first conductive portion (for example, first conductive portion 41) located inside the ceramic substrate and connecting the first end and the first terminal portion, and a second conductive portion (for example, second conductive portion 42) located inside the ceramic substrate and connecting the second end and the second terminal portion, and the recess may overlap with at least a portion of the first conductive portion and at least a portion of the second conductive portion in a planar perspective view.

[0063] (3) In the heater of (1) or (2) above, the ceramic substrate has a third surface (for example, side surface 10c) and a fourth surface (for example, side surface 10d) that are connected to and positioned opposite the first surface, and the recess may be positioned from the third surface to the fourth surface.

[0064] (4) In the heater according to any one of (1) to (3) above, the recess may extend linearly in a direction perpendicular to the longitudinal direction of the ceramic substrate.

[0065] (5) In the heater of (4) above, the depth of the recess may be constant in the extending direction of the recess.

[0066] (6) In any one of the heaters (1) to (5) above, the recess may have a bottom surface (for example, bottom surface 15a) and two side surfaces (for example, side surfaces 15b and 15c) that intersect with the longitudinal direction of the ceramic substrate.

[0067] (7) In the heater of (6) above, the two side surfaces of the recess may extend parallel to each other.

[0068] (8) In the heater of any one of (1) to (7) above, a coating material containing a plurality of boron nitride particles may be applied to at least a portion of the first surface, excluding the recessed portion.

[0069] (9) In the heater of (8) above, at least some of the boron nitride particles applied to the first surface may be positioned in a state separated from other boron nitride particles.

[0070] (10) In any one of the heaters (1) to (9) above, the ceramic substrate may have a third surface and a fourth surface that are connected to the first surface and positioned opposite each other, and the terminal portions may be positioned on the third surface and the fourth surface.

[0071] (11) The heater according to any one of (1) to (10) above may include a first recess located on the first surface of the ceramic substrate and a second recess located on the second surface.

[0072] (12) Any one of the heaters (1) to (11) above may further include a cylindrical member into which a portion of the ceramic substrate is inserted and which holds the ceramic substrate, and a bonding material which bonds the ceramic substrate to the cylindrical member, and the recess may be located between the heating resistor and the cylindrical member in a planar perspective view.

[0073] (13) The heater includes a ceramic substrate, a heating resistor, and a terminal portion. The ceramic substrate has a first surface and a second surface located opposite the first surface. The heating resistor is located at one end of the interior of the ceramic substrate. The terminal portion is located at the other end of the ceramic substrate. One of the two main surfaces of the ceramic substrate may include a protrusion (e.g., protrusion 80) between the heating resistor and the terminal portion.

[0074] (14) In the heater of (13) above, the protrusions may be integral with the ceramic substrate.

[0075] The disclosed embodiments should be considered in all respects as illustrative and not restrictive. Indeed, the above-described embodiments may be embodied in various forms. Furthermore, the above-described embodiments may be omitted, substituted, or modified in various ways without departing from the scope and spirit of the appended claims.

[0076] REFERENCE SIGNS LIST 1 heater 10 ceramic substrate 15 recess 20 heating resistor 30 terminal portion 41 first conductive portion 42 second conductive portion 50 lead wire

Claims

1. A heater comprising: a ceramic substrate having a first surface and a second surface located opposite the first surface; a heating resistor located at one end inside the ceramic substrate; and a terminal portion located at the other end of the ceramic substrate, wherein the first surface has a recess between the heating resistor and the terminal portion.

2. The heater according to claim 1, wherein the heating resistor has a first end and a second end, the terminal portion has a first terminal portion and a second terminal portion, a first conductive portion located inside the ceramic substrate and connecting the first end and the first terminal portion, and a second conductive portion located inside the ceramic substrate and connecting the second end and the second terminal portion, and the recess overlaps with at least a portion of the first conductive portion and at least a portion of the second conductive portion in a planar perspective view.

3. A heater as described in claim 1 or 2, wherein the ceramic substrate has a third surface and a fourth surface each connected to the first surface and positioned opposite each other, and the recess is positioned from the third surface to the fourth surface.

4. A heater according to any one of claims 1 to 3, wherein the recess extends linearly in a direction perpendicular to the longitudinal direction of the ceramic substrate.

5. The heater according to claim 4, wherein the depth of said recess is constant in the extending direction of said recess.

6. A heater according to any one of claims 1 to 5, wherein the recess has a bottom surface and two side surfaces intersecting with the longitudinal direction of the ceramic substrate.

7. The heater according to claim 6, wherein the two side surfaces of the recess extend parallel to each other.

8. A heater according to any one of claims 1 to 7, wherein a coating material containing a plurality of boron nitride particles is applied to at least a portion of the area of ​​said first surface excluding said recess.

9. The heater of claim 8, wherein at least a portion of said plurality of boron nitride particles applied to said first surface are spaced apart from other said boron nitride particles.

10. A heater as described in any one of claims 1 to 9, wherein the ceramic substrate has a third surface and a fourth surface each connected to the first surface and positioned opposite each other, and the terminal portions are positioned on the third surface and the fourth surface.

11. A heater according to any one of claims 1 to 10, comprising a first recess located in said first surface and a second recess located in said second surface.

12. A heater as described in any one of claims 1 to 11, further comprising: a cylindrical member into which a portion of the ceramic substrate is inserted and which holds the ceramic substrate; and a bonding material which bonds the ceramic substrate to the cylindrical member, wherein the recess is located between the heating resistor and the cylindrical member in a plan view.

13. A heater comprising: a ceramic substrate having a first surface and a second surface located opposite the first surface; a heating resistor located at one end inside the ceramic substrate; and a terminal portion located at the other end of the ceramic substrate, wherein the first surface has a convex portion between the heating resistor and the terminal portion.

14. The heater of claim 13, wherein said protrusions are integral with said ceramic substrate.

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