JP7629991B2 - heater - Google Patents

Description

The present disclosure relates to heaters used as heaters for heating liquids, heaters for heating gases, or heaters for oxygen sensors, etc.

A known example of a heater used in a liquid heating heater is the ceramic heater described in Patent Document 1. The ceramic heater described in Patent Document 1 comprises a core material having a heat generating portion therein, a connection terminal portion provided on the side of the core material and connected to the heat generating portion, and a lead terminal having one end joined to the connection terminal portion by a brazing material and the other end extending along the length of the ceramic heater.

JP 2016-81608 A

The heater of the present disclosure comprises a cylindrical or tubular ceramic body extending from a first end to a second end, a heating resistor located inside the ceramic body, an electrode pad electrically connected to the heating resistor, a lead terminal electrically connected to the electrode pad, and a conductive bonding material that bonds the electrode pad and the lead terminal, and the electrode pad is located from the side to the end face of the ceramic body.

FIG. 1A is a perspective view showing an example of a heater. FIG. 1B is a schematic perspective view showing a part of the heater shown in FIG. 1A. FIG. 2A is an enlarged cross-sectional view of the heater shown in FIG. 1A taken along line A-A'. FIG. 2B is an enlarged cross-sectional view of the heater shown in FIG. 1A taken along line B-B'. FIG. 3 is an enlarged cross-sectional view of the heater shown in FIG. 1A. FIG. 4 is an enlarged cross-sectional view showing another example of the heater. FIG. 5 is an enlarged cross-sectional view showing another example of the heater. FIG. 6 is an enlarged cross-sectional view showing another example of the heater. FIG. 7 is an enlarged cross-sectional view showing another example of the heater. FIG. 8 is an enlarged cross-sectional view showing another example of the heater. FIG. 9 is an enlarged cross-sectional view showing another example of the heater. FIG. 10 is an enlarged cross-sectional view showing another example of the heater. FIG. 11 is a side view showing another example of the heater. FIG. 12 is a plan view showing another example of the heater. FIG. 13 is a plan view showing another example of the heater.

For such ceramic heaters, a terminal connection part is provided on one surface of the core material. This raises the risk that the bonding strength of the terminal connection part may not be maintained when vibration occurs in a direction that separates the core material from the terminal connection part. This raises the risk that the terminal connection part may peel off from the core material after long-term use. As a result, it has been difficult to improve the long-term reliability of the ceramic heater.

In one embodiment of the heater disclosed herein, the electrode pads are located from the side to the end face of the ceramic body. This allows the electrode pads to be provided on multiple faces of the ceramic body. This allows the bonding strength of the electrode pads to be maintained even if vibration occurs in a direction that separates the ceramic body from the electrode pads. This reduces the risk of the electrode pads peeling off from the ceramic body even after long-term use. As a result, the long-term reliability of the heater can be improved.

The heater 100 is described in detail.

Figure 1A is a perspective view showing an example of a heater 100. Figure 1B is a schematic perspective view showing a part of the heater shown in Figure 1A. As shown in Figures 1A and 1B, the heater 100 includes a cylindrical or tubular ceramic body 1 extending from a first end 101 to a second end 102, a heating resistor 2 located inside the ceramic body 1, an electrode pad 3 electrically connected to the heating resistor 2, a lead terminal electrically connected to the electrode pad 3, and a conductive bonding material 5 that bonds the electrode pad 3 and the lead terminal 4, and the electrode pad 3 is located from the side to the end face of the ceramic body 1.

1A and 1B, the lower left of the heater 100 is the first end 101, and the upper right is the second end 102. In FIG. 3, the upper part is the first end 101, and the lower part is the second end 102. In the following description, the terms "first end 101 side" and "second end 102 side" may be used, but the part closer to the first end 101 is the "first end 101 side" and the part closer to the second end 102 is the "second end 102 side" based on the center in the longitudinal direction, which is the direction in which the ceramic body 1 extends. The "first end 101 side" can also be referred to as the vicinity of the first end 101, and the "second end 102 side" can also be referred to as the vicinity of the second end 102.

The ceramic body 1 is a member provided to protect the heating resistor 2. The shape of the ceramic body 1 is a columnar or cylindrical shape having a longitudinal direction. In the heater 100 shown in FIG. 1, the ceramic body 1 is cylindrical.

The ceramic body 1 comprises an insulating ceramic material, such as alumina, silicon nitride, or aluminum nitride. When the ceramic body 1 is cylindrical, the dimensions of the ceramic body 1 can be, for example, a length of 10 to 400 mm and an outer diameter of 5 to 60 mm. When the ceramic body 1 is cylindrical, the dimensions of the ceramic body 1 can be, for example, a length of 10 to 400 mm, an outer diameter of 5 to 60 mm, and an inner diameter of 3 to 50 mm.

Furthermore, as shown in Figures 1A and 1B, the ceramic body 1 may have a slit-shaped recess on its outer surface extending from the first end 101 to the second end 102.

The heating resistor 2 is a member for generating heat by the flow of current. The heating resistor 2 is provided inside the ceramic body 1 as shown in FIG. 1B, FIG. 2A, and FIG. 2B. The heating resistor 2 may be arranged so that it generates the most heat on the second end 102 side of the ceramic body 1. For example, the heating resistor 2 may extend from the first end 101 side of the ceramic body 1 toward the second end 102 side, and when it reaches the second end 102 side, it may extend from the second end 102 side toward the other first end 101 side. In addition, the heating resistor 2 may have a folded portion provided along the circumferential direction while repeatedly folding back in the length direction on the second end 102 side of the ceramic body 1 as shown in FIG. 1B. In addition, the heating resistor 2 may have a pair of straight portions on the second end 102 side of the folded portion. The heating resistor 2 may have a pattern in which the repeatedly folded back fold is not limited to only on the second end 102 side, but may have a pattern in which the folded back fold is repeatedly folded back and forth between the first end 101 side and the second end 102 side.

The heating resistor 2 has a metal material. The metal material has, for example, tungsten, molybdenum, or rhenium. The heating resistor 2 may have an insulating member. This allows the resistance value of the heating resistor 2 to be adjusted. The dimensions of the heating resistor 2 can be set, for example, to a width of 0.2 to 5 mm, a total length of 5 to 1000 mm, and a thickness of 0.05 to 0.5 mm.

The electrode pad 3 is a member for connecting the lead terminal 4 and the heating resistor 2. The electrode pad 3 is provided from the side to the end face of the ceramic body 1. The electrode pad 3 is electrically connected to the heating resistor 2. The electrode pad 3 has a metal material. The metal material includes, for example, tungsten, molybdenum, and rhenium. Furthermore, a layer of metal such as nickel, chromium, or gold may be applied to the surface. The dimensions of the part of the electrode pad 3 provided on the side of the ceramic body 1 can be 0.5 to 15 mm in length, 0.5 to 5 mm in width, and 0.2 to 1.5 mm in thickness. The dimensions of the part of the electrode pad 3 provided on the end face of the ceramic body 1 can be 0.1 to 20 mm in length, 0.1 to 20 mm in width, and 0.2 to 1.5 mm in thickness. As shown in FIG. 1, the electrode pad 3 and the lead terminal 4 may be provided on both ends of the heating resistor 2.

As shown in Fig. 2B, the electrode pad 3 and the heating resistor 2 may be electrically connected, for example, via a through-hole conductor. This allows the lead terminal 4 provided on the outer periphery of the ceramic body 1 to be electrically connected to the heating resistor 2 provided inside the ceramic body 1.

The lead terminal 4 is a member for supplying power to the heating resistor 2. The lead terminal 4 is electrically connected to an external power source. The lead terminal 4 is electrically joined to the electrode pad 3 and extends in the longitudinal direction of the ceramic body 1. The lead terminal 4 is, for example, a wire-shaped, rod-shaped, cylindrical, strip-shaped, or string-shaped member. The cross-sectional shape of the lead terminal 4 may be, for example, a circle, an ellipse, a polygonal shape such as a triangle or a rectangle, or may be hollow in any of these shapes. In the lead terminal 4 shown in FIG. 1, the lead terminal 4 is cylindrical. When the lead terminal 4 is cylindrical, for example, the dimensions of the lead terminal 4 can be a diameter of 0.5 to 5 mm and a length of 10 to 300 mm. The lead terminal 4 can be a wire or plate made of nickel or copper metal.

The bonding material 5 is a member for firmly fixing the lead terminal 4 and the electrode pad 3. The bonding material 5 is located on the electrode pad 3. The bonding material 5 may be a conductive metal material such as silver, copper, or tin.

In the sample holder of this embodiment, as shown in Figures 1A, 1B, 2A and 2B, the heater 100 includes a cylindrical or tubular ceramic body 1 extending from a first end 101 to a second end 102, a heating resistor 2 located inside the ceramic body 1, an electrode pad 3 electrically connected to the heating resistor 2, a lead terminal 4 electrically connected to the electrode pad 3, and a conductive bonding material 5 that bonds the electrode pad 3 and the lead terminal 4, and the electrode pad 3 is located from the side to the end face of the ceramic body 1. This allows the electrode pad 3 to be provided on multiple faces of the ceramic body 1. This allows the bonding strength of the electrode pad 3 to be maintained even if vibration occurs in the direction in which the ceramic body 1 and the electrode pad 3 are separated. This reduces the risk that the electrode pad 3 will peel off from the ceramic body 1 even after long-term use. As a result, the long-term reliability of the heater 100 can be improved.

Also, as shown in FIG. 3, the ceramic body 1 has a first portion 11 including the outer periphery of the ceramic body 1, and a second portion 12 located adjacent to the central axis and following the first portion 11, the first portion 11 having a first side surface 111 including the outer periphery and a first end surface 112 following the first side surface 111, and the second portion 12 may have a second side surface 121 extending toward the second end 102 and following the first end surface 112, and a second end surface 122 following the second side surface 121.

1 includes the first side surface 111 and the second side surface 121, and the "end surface" includes the first end surface 112 and the second end surface 122. At this time, the second part 12 has the second side surface 121 extending from the first end surface 112 toward the second end 102 and the second end surface 122 continuing from the second side surface 121, so that a step can be provided between the second part 12 and the first part 11. This allows a space to be provided between the lead terminal 4, the first end surface 112, and the second side surface 121 to store the bonding material 5. This allows more bonding material 5 to be added. This allows the bonding strength between the lead terminal 4 and the ceramic body 1 to be increased. As a result, the long-term reliability of the heater 100 can be improved.

Also, as shown in FIG. 3, the electrode pad 3 may be located from the first side surface 111 to the first end surface 112. In this case, the second side surface 121 and the second end surface 122 may have a portion where the electrode pad 3 is not provided. Also, the second side surface 121 and the second end surface 122 may have a portion where the bonding material 5 is not provided. By the electrode pad 3 being located from the first side surface 111 to the first end surface 112, the bonding strength of the electrode pad 3 can be maintained even if vibration occurs in the direction in which the ceramic body 1 and the electrode pad 3 move away from each other, compared to the case where the ceramic body 1 has the electrode pad 3 on one surface. This reduces the risk that the electrode pad 3 will peel off from the ceramic body 1 even when used for a long time. As a result, the long-term reliability of the heater 100 can be improved.

Also, as shown in FIG. 4, the electrode pad 3 may be located from the first end face 112 to the second side face 121. In this case, the second end face 122 may have a portion where the electrode pad 3 is not provided. Also, the second end face 122 may have a portion where the bonding material 5 is not provided. By the electrode pad 3 being located from the first end face 112 to the second side face 121, the electrode pad 3 can cover the area between the first end face 112 and the second side face 121, which is the boundary between the first part 11 and the second part 12. Therefore, the risk of cracks occurring between the first end face 112 and the second side face 121 of the ceramic body 1 can be reduced. As a result, the long-term reliability of the heater 100 can be improved. The first part 11 is a part that can be called a surface layer, and the second part 12 is a part that can be called a core.

Also, as shown in FIG. 5, the electrode pad 3 may be located from the second side surface 121 to the second end surface 122. In this case, the first end surface 112 and the second side surface 121 may be provided with the electrode pad 3 and the bonding material 5. By positioning the electrode pad 3 from the second side surface 121 to the second end surface 122, the electrode pad 3 can be provided on more surfaces of the ceramic body 1. This allows the bonding strength of the electrode pad 3 to be maintained even if vibration occurs in the direction in which the ceramic body 1 and the electrode pad 3 move away from each other. This reduces the risk that the electrode pad 3 will peel off from the ceramic body 1 even when used for a long time. As a result, the long-term reliability of the heater 100 can be improved.

6, the heating resistor 2 may be located between the first portion 11 and the second portion 12, with an end protruding from the first end 101 surface 112, and the end joined to the electrode pad 3. This increases the number of paths through which current flows from the lead terminal 4 to the heating resistor 2. This reduces the risk that the lead terminal 4 and the heating resistor 2 will no longer be electrically connected. As a result, the long-term reliability of the heater 100 can be improved.

7, the bonding material 5 may be provided in a meniscus shape from the first end face 112 to the second side face 121. This allows the bonding material 5 to cover the interface between the first end face 112 and the second side face 121, reducing the risk of cracks occurring at the interface between the first end face 112 and the second side face 121 of the ceramic body 1. As a result, the long-term reliability of the heater 100 can be improved.

7, the bonding material 5 is provided in a meniscus shape from the first end surface 112 to the lead terminal 4, and may have a space between the second side surface 121 and the lead terminal 4. This allows the lead terminal 4 and the ceramic body 1 to be firmly fixed by the bonding material, while the space between the second side surface 121 and the lead terminal 4 forms an area in which the bonding material 5 can thermally expand. This reduces the risk of thermal stress occurring between the lead terminal 4 and the bonding material 5 due to thermal expansion of the bonding material 5. This reduces the risk of cracks occurring between the lead terminal 4 and the bonding material 5. As a result, the long-term reliability of the heater 100 can be improved.

8, the bonding material 5 may be positioned between the second side surface 121 and the lead terminal 4. This allows the bonding material 5 to firmly fix the lead terminal 4 and the ceramic body 1. This reduces the risk of the lead terminal 4 and the ceramic body 1 peeling off. As a result, the long-term reliability of the heater 100 can be improved. Here, the space between the second side surface 121 and the lead terminal 4 refers to the area surrounded by the imaginary extension line of the first side surface 111 and the imaginary extension line of the second end 102 surface 122.

Also, as shown in FIG. 9, the lead terminal 4 may be curved. Here, "curved" means that the portion connecting the portion electrically connected to the electrode pad 3 and the portion extending toward the first end 101 is curved, as shown in FIG. 9. This allows the generated vibration to be dispersed. This allows the bonding strength between the lead terminal 4 and the bonding material 5 to be maintained. This reduces the risk of the lead terminal 4 and the bonding material 5 peeling off. As a result, the long-term reliability of the heater 100 can be improved. The closer the angle between the portion electrically connected to the electrode pad 3 and the portion extending toward the first end 101 is to 90 degrees, the greater the effect of the curved connecting portion.

10, the bonding material 5 may extend along the first side surface and across to the second side surface, with a gap between the bonding material 5 and the first end 101 surface 121. This allows the bonding material 5 to thermally expand up to the area where the first portion 11 is exposed. This reduces the risk of thermal stress occurring between the lead terminal 4 and the bonding material 5 due to thermal expansion of the bonding material 5. This reduces the risk of cracks occurring between the lead terminal 4 and the bonding material 5. As a result, the long-term reliability of the heater 100 can be improved.

Also, as shown in FIG. 11, the electrode pad 3 may be thinner on the first end 101 side than on the second end 102 side of the ceramic body 1. Here, "thin" means that the length of the electrode pad 3 on the first end 101 side of the ceramic body 1 is shorter than the second end 102 side in the circumferential direction of the ceramic body 1. This allows the distance between the two electrode pads 3 to be increased when there are two lead terminals 4 at the first end 101 of the ceramic body 1 and corresponding electrode pads 3. This reduces the risk of the two electrode pads 3 being connected, and reduces the risk of a short circuit. As a result, the long-term reliability of the heater 100 can be improved. The electrode pad 3 may be stepped so that the first end 101 side of the ceramic body 1 is thinner than the second end 102 side, but if the first end 101 side of the ceramic body 1 is tapered, stress can be reduced more than if it is stepped.

12, the electrode pad 3 may be tapered toward the center of the second portion 12 when viewed from the first end 101 side of the ceramic body 1. This allows the two electrode pads 3 provided on the end faces of the ceramic body 1 to be spaced apart. This reduces the risk of a short circuit occurring at the end faces of the ceramic body 1. As a result, the long-term reliability of the heater 100 can be improved.

13, when viewed from the first end 101 side of the ceramic body 1, the outer periphery lengths of the two electrode pads 3 may be different. This makes it possible to distinguish the anode and the cathode when joining the heater 100 to another component. This makes it possible to accurately connect the heater 100 to another member.

13, when viewed from the first end 101 side of the ceramic body 1, the inner periphery lengths of the two electrode pads 3 may be different. This makes it possible to distinguish the anode and the cathode when joining the heater 100 to another component. This makes it possible to accurately connect the heater 100 to another member.

In particular, by making the outer circumference of the cathode electrode pad 3 longer than that of the anode, and by lengthening the inner circumference, the diameter and number of the lead terminals 4 attached to the cathode electrode pad 3 can be made larger for the cathode than for the anode, so that the cathode lead terminals 4 can be grounded and used to fix the heater 100.

1: Ceramic body 101: First end 102: Second end 11: First portion 111: First side surface 112: First end surface 12: Second portion 121: Second side surface 122: Second end surface 2: Heating resistor 3: Electrode pad 4: Lead terminal 5: Bonding material 100: Heater

Claims (10)

a cylindrical or tubular ceramic body extending from a first end to a second end;
a heating resistor located inside the ceramic body;
an electrode pad electrically connected to the heating resistor;
a lead terminal electrically connected to the electrode pad;
a conductive bonding material that bonds the electrode pad and the lead terminal,
The electrode pad is located from a side surface to an end surface of the ceramic body ,
the ceramic body has a first portion including an outer periphery of the ceramic body and a second portion adjacent to the first portion and located near a central axis;
The first portion has a first side surface including the outer periphery and a first end surface continuing from the first side surface,
The second portion has a second side surface extending from the first end surface toward the second end, and a second end surface continuing from the second side surface . The heater according to claim 1 , wherein the electrode pad is located from the first side surface to the first end surface. The heater according to claim 2 , wherein the electrode pad is located from the first end surface to the second side surface. The heater according to claim 3 , wherein the electrode pad is located from the first side surface to the second end surface. the heating resistor is located between the first portion and the second portion, and an end portion of the heating resistor protrudes from the first end surface,
The heater according to claim 1 , wherein the end and the electrode pad are joined. The heater according to claim 1 , wherein the bonding material is positioned in a meniscus shape from the first end surface to the second side surface. The heater according to claim 1 , wherein the bonding material is positioned in a meniscus shape from the first end surface to the lead terminal, and a space is defined between the second side surface and the lead terminal. The heater according to claim 1 , wherein the bonding material is located so as to fill a space between the second side surface and the lead terminal. The heater according to claim 1, wherein the lead terminal is curved at a portion connecting the portion electrically connected to the electrode pad and the portion extending in the longitudinal direction of the ceramic body. the bonding material extends along the first side surface and across the second side surface,
The heater according to claim 1 , further comprising a gap between the bonding material and the first end surface.

Images