JP6708386B2 - heater - Google Patents

Description

The present invention relates to a heater used for a liquid heating heater, a powder heating heater, a gas heating heater, an oxygen sensor heater, and the like.

As a heater used for a heater for liquid heating, a heater for powder heating, a heater for gas heating, a heater for oxygen sensor, etc., for example, a heater device disclosed in Patent Document 1 is known. The heater device disclosed in Patent Document 1 includes a ceramic body in which a heating resistor is embedded, an electrode pad provided on the surface of the ceramic body, and a terminal member joined to the electrode pad.

JP, 2011-60712, A

The heater device disclosed in Patent Document 1 is provided such that the terminal member rises from the ceramic body. The terminal member is joined to the electrode pad by a brazing material. In the heater device having such a configuration, it is difficult to improve the bonding strength between the terminal member and the electrode pad because the area where the end surface of the terminal member and the surface of the electrode pad face each other is small. Further, when the joining with the brazing material is performed, the air located between the terminal member and the electrode pad may remain between them. In such a case, there is a possibility that the brazing material may not easily flow between the terminal member and the electrode pad. When the area where the end surface of the terminal member and the surface of the electrode pad face each other is small, the effect of the remaining air is large, and it is possible to sufficiently bring the brazing material into contact with the end surface of the terminal member and the surface of the electrode pad. There was a case where it could not be done.

A heater according to one aspect of the present invention includes a rod-shaped or cylindrical ceramic body, a heating resistor provided inside the ceramic body, and an electrode provided on the surface of the ceramic body and connected to the heating resistor. A layer and a lead terminal joined to the electrode layer via a joining material, the lead terminal having an end face joined to the electrode layer and having a protrusion on a peripheral portion of the end face. , The tip of the protrusion is in contact with the electrode layer, and when the protrusion is the first protrusion, the bonding material is spread over a part of the end surface and the outer peripheral surface of the lead terminal, and the lead terminal, A second projection is provided on a portion of the outer peripheral surface where the bonding material is spread .

According to the heater of one aspect of the present invention, the bonding material can be easily wet and spread on the end surface of the lead terminal. Thereby, the bonding strength between the lead terminal and the electrode layer can be improved.

It is a longitudinal section showing an example of a heater of this embodiment. It is an enlarged view which shows the junction part of an electrode layer and a lead terminal among the heaters shown in FIG. FIG. 2 is a cross-sectional view showing a joint portion between an electrode layer and a lead terminal in the heater shown in FIG. 1. It is a longitudinal section showing a modification of a heater.

The heater 10 as an example of this embodiment will be described in detail.

FIG. 1 is a vertical cross-sectional view showing an example of an embodiment of the heater 10 of this embodiment. As shown in FIG. 1, the heater 10 includes a rod-shaped or tubular ceramic body 1, a heating resistor 2 provided inside the ceramic body 1, and an electrode layer 3 provided on the surface of the ceramic body 1. , And a lead terminal 4 joined to the electrode layer 3.

The ceramic body 1 is a member provided to protect the heating resistor 2. The shape of the ceramic body 1 is a rod shape or a cylinder shape. Examples of the rod shape include a columnar shape such as a columnar shape or a prismatic shape. The columnar shape here also includes, for example, a plate shape elongated in a specific direction. Examples of the tubular shape include a cylindrical shape and a rectangular tubular shape. In the heater 10 shown in FIG. 1, the ceramic body 1 has a columnar shape.

The ceramic body 1 is made of an insulating ceramic material. Examples of the insulating ceramic material include alumina, silicon nitride, and aluminum nitride. It is preferable to use aluminum nitride from the viewpoint of excellent thermal conductivity. In particular, when aluminum nitride is used, the thermal conductivity of the ceramic body 1 can be increased to 150 W/(m·K), so the heat generated by the heating resistor 2 formed inside the ceramic body 1 is generated by the heater 10. It can be efficiently transmitted to the surface. Therefore, the temperature of the heater 10 can be rapidly raised.

Further, it is preferable to use alumina from the viewpoint of ease of production. When the ceramic body 1 has a cylindrical shape, the dimensions of the ceramic body 1 can be set, for example, to a length of 100 mm and an outer diameter of 20 mm. When the ceramic body 1 is plate-shaped, the dimensions of the ceramic body 1 can be set to, for example, a length of 80 mm, a width of 50 mm, and a thickness of 2 mm. When the ceramic body 1 has a cylindrical shape, the dimensions of the ceramic body 1 can be set to 100 mm in length, 20 mm in outer diameter, and 14 mm in inner diameter, for example.

The heating resistor 2 is a resistor that generates heat when a current flows. The heating resistor 2 is provided inside the ceramic body 1. That is, the heating resistor 2 is embedded in the ceramic body 1. The heating resistor 2 in the heater 10 of this embodiment has a folded shape. Both ends of the heating resistor 2 are connected to the extraction electrodes 21. The extraction electrode 21 is drawn to one end of the ceramic body 1, and is drawn to the outer peripheral surface of the ceramic body 1 at the end.

The folded portion of the heating resistor 2 is provided at the other end of the ceramic body 1. That is, the extraction electrode 21 is provided in the region of the ceramic body 1 opposite to the folded portion of the heating resistor 2. Both ends of the heating resistor 2 are electrically connected to the electrode layers 3 provided on the outer peripheral surface of the ceramic body 1 via the extraction electrodes 21.

The heating resistor 2 is made of a metal material. Examples of the metal material include tungsten, molybdenum, and rhenium. The heating resistor 2 can be set to have a width of 1 mm, a total length of 3000 mm and a thickness of 0.02 mm, for example. The extraction electrode 21 can be formed simultaneously with the heating resistor 2 by using the same metal material as that of the heating resistor 2. The extraction electrode 21 can also be formed separately using a material different from that of the heating resistor 2.

The electrode layer 3 is provided on the surface of the ceramic body 1. The electrode layer 3 is connected to the heating resistor 2 via the extraction electrode 21. The electrode layer 3 is made of a metal material. Examples of the metal material include tungsten, molybdenum, and rhenium. The dimensions of the electrode layer 3 can be set to a length of 9 mm, a width of 5 mm, and a thickness of 0.02 mm, for example. In addition, in the present embodiment, the electrode layer 3 is connected to the heating resistor 2 via the extraction electrode 21, but not limited to this. Specifically, the heater 10 may not have the extraction electrode 21, and the electrode layer 3 and the heating resistor 2 may be directly connected.

The lead terminal 4 is a member for supplying electric power to the heating resistor 2. The lead terminal 4 is used by being connected to an external power source (not shown). As the lead terminal 4, a wire or plate made of nickel or copper metal can be used. The lead terminal 4 can be attached on the surface of the electrode layer 3 by using the bonding material 5. As the joining material 5, for example, a brazing material can be used.

The lead terminal 4 includes a first portion 41 that rises from the electrode layer 3, a second portion 42 that extends from the outer periphery of the ceramic body 1 along the length direction on the outer side, and a first portion 41 via the outer side of the second portion 42. The curved portion 43 that connects the first portion 41 and the second portion 42 is provided. As a result, when vibration occurs in the length direction of the ceramic body 1, the bending portion 43 bends, so that this vibration can be reduced. Therefore, the stress generated at the joint between the first portion 41 and the electrode layer 3 can be reduced. As a result, the strength of the ceramic body 1 against vibration in the longitudinal direction can be improved.

In the present embodiment, the cross section of the lead terminal 4 (cross section of the first portion 41, the second portion 42, and the curved portion 43) is circular. In particular, since the curved portion 43 has a circular cross section, it is possible to reduce the possibility that the curved portion 43 is damaged when the curved portion 43 bends. Examples of other shapes of the cross section of the lead terminal 4 include a rectangular shape, a U-shape, and a hollow shape. In particular, when the curved portion 43 has a U-shaped cross-section, the open side of the U-shaped portion is located on the side opposite to the ceramic body 1 (that is, on the outer peripheral side of the curved portion 43). Preferably. Thereby, the bending portion 43 can be easily bent. The U-shape here includes, for example, a case where the corners are round, such as a so-called C-shape.

Further, in the present embodiment, the shape and size of the cross section of the first portion 41, the second portion 42, and the curved portion 43 of the lead terminal 4 are the same, but the present invention is not limited to this. Specifically, the shape and size may be different in each part. In particular, the curved portion 43 is preferably thinner than the first portion 41 and the second portion 42. As a result, the bending portion 43 can be easily bent while ensuring the strength of the lead terminal 4.

The size of the lead terminal 4 can be set as follows, for example. In the case of the heater 10 shown in FIG. 1, the length of the first portion 41 can be set to 2.3 mm. Regarding the length of the curved portion 43, the length in the direction perpendicular to the length direction of the ceramic body 1 can be set to 1.5 mm, and the length in the direction parallel to the length direction of the ceramic body 1 can be set to 2.5 mm. Further, the length of the second portion 42 can be set to 6.5 mm. Moreover, the cross section of each of the first portion 41, the second portion 42, and the curved portion 43 can be set to a circular shape having a diameter of Φ 0.8 mm.

Here, as shown in FIGS. 2 and 3, in the present embodiment, the lead terminal 4 has an end face joined to the electrode layer 3 and a projection 6 at the peripheral edge portion of the end face. In FIG. 2, the bonding material 5 is omitted in order to clarify the relationship between the lead terminal 4 and the electrode layer 3. Thereby, the bonding material 5 can be easily wet and spread on the end surface of the lead terminal 4. Therefore, the bonding strength between the lead terminal 4 and the electrode layer 3 can be improved. The reason why the bonding material 5 easily wets and spreads on the end surface of the lead terminal 4 is considered as follows. That is, when joining the lead terminal 4 and the electrode layer 3, the joining material 5 contacting the side surface of the lead terminal 4 propagates along the protrusion 6 and spreads wet on the end surface of the lead terminal 4. At this time, since the interval between the lead terminal 4 and the electrode layer 3 is partially narrowed due to the provision of the protrusion 6, the air located in the vicinity is pushed out by the bonding material that spreads the protrusion 6 wet. be able to. Then, the bonding material 5 transmitted through the protrusions 6 spreads over the entire surface of the end surface of the lead terminal 4, so that air can be pushed out from the place where the protrusions 6 are not provided. As a result, it is possible to reduce the large bubbles remaining between the lead terminal 4 and the electrode layer 3, so that the bonding strength between the lead terminal 4 and the electrode layer 3 can be improved. Moreover, since the contact area between the lead terminal 4 and the bonding material 5 can be increased by providing the protrusion 6, the bonding strength between the lead terminal 4 and the electrode layer 3 can be improved. The protrusion 6 has a pointed tip, for example, a conical shape. The dimensions of the protrusions 6 can be set such that the width of the largest portion is 50 μm to 500 μm and the height is 20 to 300 μm.

Furthermore, the end surface of the lead terminal 4 may have a plurality of protrusions 6 on the peripheral edge. In this case, the contact area between the end surface of the lead terminal 4 including the protrusion 6 and the bonding material 5 can be increased. Thereby, the bonding strength between the lead terminal 4 and the electrode layer 3 can be improved.

Furthermore, the tips of the protrusions 6 may be in contact with the electrode layer 3. Since the tips of the protrusions 6 are in contact with the electrode layer 3, the lead terminals 4 can be easily positioned. Thereby, the distance between the lead terminal 4 and the electrode layer 3 can be made constant, so that the amount of the bonding material 5 can be easily adjusted. This can reduce the possibility that the bonding material 5 is too much or too little, so that the bonding strength between the lead terminal 4 and the electrode layer 3 can be stabilized.

As shown in FIG. 4, when the protrusion 6 is the first protrusion 6, the bonding material 5 spreads over a part of the end surface and the outer peripheral surface of the lead terminal 4, and the lead terminal 4 is bonded to the outer peripheral surface of the bonding material 5. You may have the 2nd protrusion 7 in the spreading part. As a result, the second protrusion 7 is caught by the bonding material 5 when an external force in the bending direction is applied to the portion (first portion 41) where the lead terminal 4 rises vertically from the electrode layer 3. As a result, it is possible to reduce the risk that the lead terminal 4 will come off from the bonding material 7.

The second protrusion 7 may protrude along the length direction of the second portion 42. The external force applied to the joint portion between the lead terminal 4 and the electrode layer 3 tends to have a large force particularly in the length direction of the second portion 42. Therefore, by projecting the second protrusion 7 along the second portion 42, when a large force is applied in the length direction of the second portion 42 and the lead terminal 4 is about to come off from the bonding material 5, The second portion 42 can be scratched on the bonding material 5. Therefore, it is possible to further reduce the risk of the lead terminal 4 coming off the bonding material 5. The dimensions of the second protrusion 7 can be set such that the width of the largest portion is 50 μm to 500 μm and the height is 10 to 300 μm.

Further, at least two second protrusions 7 may be provided, and the two second protrusions 7 may be positioned so as to face each other on the outer peripheral surface of the lead terminal 4. It should be noted that the term “opposed” here means that at least a part of the second protrusions 7 oppose each other when viewed in a cross section as shown in FIG. 3. Since the second protrusions 7 are positioned so as to face each other, the width of the lead terminal 4 is partially increased, so that the lead terminal 4 can be more difficult to come out of the bonding material 5.

1: ceramic body 2: heat generating resistor 21: extraction electrode 3: electrode layer 4: lead terminal 41: first portion 42: second portion 43: curved portion 5: bonding material 6: protrusion (first protrusion)
7: Second protrusion 10: Heater

Claims (2)

A rod-shaped or cylindrical ceramic body, a heating resistor provided inside the ceramic body, an electrode layer provided on the surface of the ceramic body and connected to the heating resistor, and a bonding material for the electrode layer. And a lead terminal joined via the electrode layer, the lead terminal having an end face joined to the electrode layer, and a protrusion at a peripheral portion of the end face, the tip of the protrusion being the electrode layer. And the bonding material spreads over a part of the end surface and the outer peripheral surface of the lead terminal when the projection is the first projection, and the lead terminal spreads the bonding material on the outer peripheral surface. A heater characterized by having a second protrusion in the portion . The heater according to claim 1, wherein the lead terminal has a plurality of protrusions on the peripheral portion of the end surface.

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