WO2020111196A1

WO2020111196A1 - Heater

Info

Publication number: WO2020111196A1
Application number: PCT/JP2019/046642
Authority: WO
Inventors: 達哉谷口
Original assignee: 京セラ株式会社
Priority date: 2018-11-29
Filing date: 2019-11-28
Publication date: 2020-06-04
Also published as: JPWO2020111196A1

Abstract

This heater comprises: an insulating substrate having one end and another end, the insulating substrate being in a rod-form or cylindrical shape; a heat-emitting resistor provided inside the insulating substrate, the heat-emitting resistor being drawn out from a side surface of the insulating substrate; an electroconductive layer provided at the site on the side surface where the heat-emitting resistor is drawn out; and a lead terminal that is electrically connected to the heat-emitting resistor via the electroconductive layer. The lead terminal has a first portion joined to the electroconductive layer, and a second portion positioned closer to the one-end side than the first portion. The second portion is set apart from the electroconductive layer, and a one-end-side end part of the second portion is positioned closer to the other-end side than a one-end-side end part of the electroconductive layer.

Description

heater

The present disclosure relates to, for example, a heater for ignition or flame detection in a combustion type in-vehicle heating device, a heater for ignition of various combustion devices such as an oil fan heater, a heater for a glow plug of a diesel engine, and various sensors such as an oxygen sensor. , A heater for various heat exchange units such as a fluid heating device or a heater used for heating a measuring instrument.

Conventionally, a rod-shaped ceramic base, a heating resistor embedded in the ceramic base, an electrode pad electrically connected to the heating resistor and provided on the outer surface of the ceramic base, and one end portion of which via the electrode pad A heater including a lead terminal connected to a ceramic base is known (for example, see Patent Document 1).

In recent years, the size of heaters has been reduced and the heat generation temperature of heaters has been increased. Along with this, the heat of the heating resistor that rapidly generates heat tends to move to the electrode pads and the lead terminals, and the thermal stress applied to the connecting portion between the ceramic base and the lead terminals tends to increase. In the conventional heater, the entire one end of the lead terminal is connected to the ceramic base through the electrode pad. Therefore, when the thermal stress applied to the connecting portion between the ceramic base and the lead terminal becomes large, the electrode pad of the lead terminal Peeling from the ceramic substrate and cracks in the ceramic substrate are likely to occur.

JP, 2017-107732, A

A heater according to one aspect of the present disclosure is a rod-shaped or tubular-shaped insulating base having one end and the other end, and a heating resistor provided inside the insulating base and extended to a side surface of the insulating base. And a conductive layer provided on a portion of the side surface where the heating resistor is drawn out, and a lead terminal electrically connected to the heating resistor via the conductive layer. The lead terminal has a first portion joined to the conductive layer, and a second portion located closer to the one end side than the first portion, and the second portion is formed from the conductive layer. The end portions on the one end side of the second portion are separated from each other and are located on the other end side with respect to the end portion on the one end side of the conductive layer.

Objects, features, and advantages of the present disclosure will become more apparent from the following detailed description and drawings.
FIG. 3 is a cross-sectional view showing a heater according to an embodiment of the present disclosure. It is a principal part expanded sectional view in the A section of FIG. FIG. 3 is an enlarged side view of a main part of a heater according to an embodiment of the present disclosure. FIG. 6 is a cross-sectional view showing a heater according to another embodiment of the present disclosure.

Hereinafter, embodiments of the heater of the present disclosure will be described in detail with reference to the drawings.

FIG. 1 is a cross-sectional view showing a heater according to an embodiment of the present disclosure, FIG. 2 is an enlarged cross-sectional view of a main part of a portion A in FIG. 1, and FIG. 3 is a cross-sectional view according to an embodiment of the present disclosure. It is a principal part expanded side view of a heater. Note that, in FIG. 3, portions other than the conductive layer and the lead terminals are omitted.

The heater 1 of the present embodiment includes an insulating substrate 10, a heating resistor 20, a conductive layer 30, and a lead terminal 40.

The insulating substrate 10 is a rod-shaped member, and has one end (hereinafter, also referred to as a first end) 11 and the other end (hereinafter, also referred to as a second end) 12 in the longitudinal direction (the left-right direction in FIG. 1). There is. The insulating substrate 10 may have a shape such as a square bar shape or a round bar shape, or may have any other shape. In the present embodiment, the insulating substrate 10 has a round bar shape. Moreover, the insulating base 10 may be configured such that the end portion on the first end 11 side has a hemispherical shape.

The insulating base 10 is made of an electrically insulating ceramic material. Examples of the ceramic material used for the insulating substrate 10 include ceramics having electrical insulation such as oxide ceramics, nitride ceramics, carbide ceramics, and silicon nitride ceramics.

The insulating base 10 has, for example, a length in the longitudinal direction of 15 to 50 mm. When the insulating base 10 is in the shape of a round rod, the insulating base 10 has, for example, a diameter of a cross section perpendicular to the longitudinal direction of 1.5 to 10 mm. In the case of a plate shape, for example, one side of the cross section is 0.5 to 3 mm, and the other side is 2 to 10 mm.

The heating resistor 20 is a member that is provided inside the insulating substrate 10 and generates heat when energized. The heating resistor 20 has an embedded portion 21 embedded in the insulating base 10 and an exposed portion 22 extended to the side surface 13 of the insulating base 10.

For example, as shown in FIG. 1, the embedded portion 21 extends in the longitudinal direction of the insulating base 10 and has two parallel portions 21 a facing each other and two parallel portions 21 a located near the first end 11 of the insulating base 10. It has a folded shape including a bent portion 21b that connects the two to each other. The exposed portion 22 is located near the second end 12 of the insulating base 10, as shown in FIG. 1, for example.

The heating resistor 20 can be mainly composed of a carbide such as tungsten (W), molybdenum (Mo) or titanium (Ti), a nitride or a silicide. Further, the heating resistor 20 may contain a material for forming the insulating substrate 10. The parallel portion 21a has, for example, a cross-sectional area of 0.15 to 3 mm ² . The bent portion 21b has, for example, a cross-sectional area of 0.15 to 0.8 mm ² . The exposed portion 22 has, for example, a cross-sectional area of 0.15 to 3 mm ² .

The heat generating resistor 20 may have a heat generating area which is a particularly heat generating area. For example, the bent portion 21b may be the heat generating area. In order to use the bent portion 21b as a heat generation area, the cross-sectional area of the bent portion 21b may be smaller than the cross-sectional area of the parallel portion 21a, and the electric resistance value per unit length of the bent portion 21b may be increased. Alternatively, by setting the content of the forming material of the insulating base 10 of the bent portion 21b larger than the content of the forming material of the insulating base 10 of the parallel portion 21a, the electric resistance per unit length of the bent portion 21b is increased. The value may be increased.

The parallel portion 21a of the heating resistor 20 has a larger cross-sectional area than the bent portion 21b, or the content of the material forming the insulating substrate 10 is smaller than that of the bent portion 21b, so that the electric resistance value per unit length is increased. May be lower than the electric resistance value of the bent portion 21b. The parallel portion 21a may be configured such that tungsten carbide (WC), which is an inorganic conductor, is a main component and silicon nitride (Si ₃ N ₄ ) is a secondary component. The parallel portion 21a may contain 15% by mass or more of silicon nitride. As the content of silicon nitride increases, the coefficient of thermal expansion of the parallel portion 21a can be brought closer to the coefficient of thermal expansion of the silicon nitride forming the insulating substrate 10. Further, when the content of silicon nitride is 40% by mass or less, the resistance value of the parallel portion 21a becomes low and stable, so that the parallel portion 21a contains 15 to 40% by mass of silicon nitride. Good.

1 shows an example in which the heating resistor 20 is a conductor pattern having two parallel portions 21a and one bent portion 21b, the heating resistor 20 may be, for example, four or more parallel portions. 21 a and three or more bent portions 21 b, and may be repeatedly folded between a portion near the first end 11 and a portion near the second end 12. Further, among the three or more bent portions 21b, the bent portion 21b located closer to the first end 11 may be a heat generating region that particularly generates heat.

The conductive layer 30 is a member that electrically connects the heating resistor 20 and an external power supply (not shown). The conductive layer 30 is provided on the side surface 13 of the insulating substrate 10 where the heating resistor 20 is drawn out, and is electrically connected to the heating resistor 20. The conductive layer 30 may cover the exposed portion 22 of the heating resistor 20, as shown in FIGS.

The conductive layer 30 is made of a metal material. Examples of the metal material used for the conductive layer 30 include silver (Ag), copper (Cu), titanium (Ti), and the like. Further, these may be coated with nickel (Ni). The conductive layer 30 may have a surface shape such as a rectangular shape, a circular shape, an elliptical shape, or any other surface shape. In the present embodiment, the conductive layer 30 has a rectangular surface shape as shown in FIG. 3, for example. The conductive layer 30 can be formed by, for example, a screen printing method. The conductive layer 30 has, for example, a length of the insulating substrate 10 in the longitudinal direction of 2 to 10 mm, a length of the insulating substrate 10 in the circumferential direction of 2 to 8 mm, and a thickness of 20 to 200 μm.

The lead terminal 40 is electrically connected to the heating resistor 20 via the conductive layer 30. The lead terminal 40 is an elongated member, and one end thereof is electrically connected to the exposed portion 22 of the heating resistor 20 via the conductive layer 30. The other end of the lead terminal 40 is electrically connected to the external power supply. Thereby, a voltage can be applied to the heating resistor 20 via the lead terminal 40, and the heating resistor 20 can generate heat. The lead terminal 40 is made of metal such as iron (Fe), chromium (Cr) or Ni.

In the heater 1 of the present embodiment, the lead terminal 40 has the first portion 41 and the second portion 42. The first portion 41 is joined to the conductive layer 30 via a brazing material, for example. As the brazing material, for example, Ag brazing, gold (Au)-Cu brazing, Ag-Cu brazing or the like can be used. The first portion 41 may have, for example, as shown in FIG. 2, a shape in which a joint portion with the conductive layer 30 is rounded. When the first portion 41 has a sharp corner at the joint with the conductive layer 30, it is likely to be a starting point for cracking of the insulating substrate 10 and separation of the lead terminal 40 from the conductive layer 30. By rounding the joining portion of the first portion 41 with the conductive layer 30, peeling of the lead terminal 40 and cracking of the insulating substrate 10 can be suppressed.

The second portion 42 is located closer to the first end 11 side than the first portion 41 and is continuous with the first portion 41. The second portion 42 extends in a direction away from the insulating base 10 and is spaced apart from the conductive layer 30, as shown in FIGS. Since the second portion 42 is not directly bonded to the conductive layer 30 and is separated from the conductive layer 30, the heated second portion 42 thermally expands when the temperature of the heater 1 rises, and its extension. Can be stretched in the direction. As a result, the heater 1 of the present embodiment can suppress the concentration of stress on the joint between the lead terminal 40 and the conductive layer 30. As a result, peeling of the lead terminal 40 from the conductive layer 30 and generation of cracks in the insulating substrate 10 can be suppressed.

Here, when the end portion 42 a of the second portion 42 on the first end 11 side is located closer to the first end 11 side than the end portion 30 a of the conductive layer 30 on the first end 11 side, the second portion 42. Absorbs the heat generated from the heat generating region (bent portion 21b) of the heat generating resistor 20, and the absorbed heat is transmitted to the first portion 41, so that the temperature difference between the first portion 41 and the conductive layer 30 increases. In some cases, thermal stress may occur at the joint between the lead terminal 40 and the conductive layer 30. In the heater 1 of the present embodiment, as shown in, for example, FIGS. 1 and 2, the end portion 42a of the second portion 42 on the first end 11 side is closer than the end portion 30a of the conductive layer 30 on the first end 11 side. It is located on the second end 12 side. This can reduce the absorption of heat generated from the heat generation region by the second portion 42, and thus can suppress the generation of thermal stress at the joint between the lead terminal 40 and the conductive layer 30. As a result, peeling of the lead terminal 40 and cracking of the insulating base 10 can be suppressed. As described above, according to the heater 1 of the present embodiment, it is possible to provide a heater having excellent durability.

It should be noted that the second portion 42 has a sufficient distance from the heat generating area (bent portion 21b) and the absorption of heat generated from the heat generating area by the second portion 42 is suppressed, so that the first end The end portion 42a on the 11th side may be located closer to the first end 11 side than the end portion 30a on the first end side of the conductive layer 30. Further, for example, as shown in FIG. 3, the second portion 42 may be located between the one end 30c and the other end 30d of the conductive layer 30 in the circumferential direction of the insulating base 10. Thereby, in the manufacturing process of the heater 1, it becomes easy to visually confirm the bonding state between the lead terminal 40 and the conductive layer 30. As a result, the reliability of the electrical connection between the lead terminal 40 and the conductive layer 30 can be improved.

The lead terminal 40 is located closer to the second end 12 side than the first portion 41, and further has a third portion 43 continuous with the first portion 41. For example, as shown in FIGS. 1 and 2, the third portion 43 extends in a direction away from the insulating substrate 10 and is separated from the conductive layer 30. Since the third portion 43 is not directly bonded to the conductive layer 30 and is separated from the conductive layer 30, the heated third portion 43 thermally expands when the temperature of the heater 1 rises and its extension. Can be stretched in the direction. As a result, it is possible to suppress the concentration of stress on the joint between the lead terminal 40 and the conductive layer 30. As a result, peeling of the lead terminal 40 and cracking of the insulating base 10 can be suppressed.

In the third portion 43, for example, as shown in FIGS. 1 and 2, the end portion 43 a on the second end 12 side is located closer to the first end 11 side than the end portion 30 b on the second end 12 side of the conductive layer 30. ing. In other words, the second portion 42 and the third portion 43 are configured to be substantially symmetrical with respect to the first portion 41. The second portion 42 and the third portion 43 cooperate with external stresses to function like springs and can disperse external stresses. Since the second portion 42 and the third portion 43 are configured to be substantially symmetrical with respect to the first portion 41, the bias of stress applied to the insulating base 10 can be reduced. As a result, it is possible to prevent stress from concentrating on a specific portion of the insulating base 10, and thus to suppress cracking of the insulating base 10.

In the heater 1, for example, as shown in FIG. 1, there are two portions where the heating resistor 20 is pulled out to the side surface 13 of the insulating substrate 10, and the conductive layer 30 and the lead terminal 40 having the above-described configuration are provided at each portion. May be provided. With such a configuration, it is possible to prevent stress from concentrating on the joint between the lead terminal 40 and the conductive layer 30 even in a situation where the rush power density at the start of energization is large. Thereby, peeling of the lead terminals 40 and cracks of the insulating substrate 10 can be suppressed.

In this embodiment, as shown in FIGS. 1 and 2, for example, an insulating adhesive material 50 is provided between the second portion 42 of the lead terminal 40 and the conductive layer 30. As the adhesive 50, for example, an adhesive such as silicone or epoxy, or an inorganic adhesive obtained by mixing ceramic powder such as alumina and an inorganic polymer can be used.

By providing the adhesive 50 between the second portion 42 and the conductive layer 30, it is possible to suppress the peeling of the lead terminal 40 from the conductive layer 30. Further, with the configuration in which the adhesive 50 is provided between the second portion 42 and the conductive layer 30, the uneven temperature distribution in the lead terminal 40 and the conductive layer 30 when the heating resistor 20 rapidly generates heat. Can be reduced. As a result, generation of thermal stress at the joint between the lead terminal 40 and the conductive layer 30 can be suppressed. As a result, peeling of the lead terminal 40 and cracking of the insulating base 10 can be suppressed.

The adhesive material 50 may be further provided between the third portion 43 and the conductive layer 30. Since the adhesive 50 is provided between the second portion 42 and the conductive layer 30 and between the third portion 43 and the conductive layer 30, the lead terminal when the heating resistor 20 suddenly generates heat. The unevenness of the temperature distribution in 40 and the conductive layer 30 can be effectively reduced. As a result, it is possible to effectively suppress the generation of thermal stress at the joint between the lead terminal 40 and the conductive layer 30. As a result, peeling of the lead terminal 40 and cracking of the insulating base 10 can be effectively suppressed.

The heater 1 further includes a tubular member 70. For example, as shown in FIG. 1, the tubular member 70 surrounds at least a portion of the insulating base 10 where the conductive layer 30 is provided in the circumferential direction of the insulating base 10. The tubular member 70 may have, for example, a cylindrical shape, for example, a cylindrical shape, a rectangular tubular shape, or the like, or may have another shape. In the heater 1 of the present embodiment, the tubular member 70 has a cylindrical shape.

As shown in FIGS. 1 and 2, for example, a portion of the insulating base 10 near the second end 12 including a portion where the conductive layer 30 is provided is inserted into the tubular member 70. For example, as shown in FIG. 1, the tubular member 70 may have a smaller inner diameter at the end portion into which the insulating base 10 is inserted. This facilitates fixing the insulating base 10 to the tubular member 70.

The inside of the tubular member 70 is filled with an insulating adhesive material 60. Examples of the adhesive 60 include an adhesive such as silicone and epoxy, or an inorganic adhesive obtained by mixing ceramic powder such as alumina and an inorganic polymer. The adhesive 60 filled in the tubular member 70 may be the same adhesive as the adhesive 50 provided between the conductive layer 30 and the second portion of the lead terminal 40, or a different adhesive. May be

The adhesive 60 may cover the joint between the lead terminal 40 and the conductive layer 30, as shown in FIG. 1, for example. Thereby, the peeling of the lead terminal 40 from the conductive layer 30 can be effectively suppressed. Further, since it is possible to suppress uneven temperature distribution in the joint portion between the lead terminal 40 and the conductive layer 30, it is possible to suppress generation of thermal stress in the joint portion between the lead terminal 40 and the conductive layer 30. As a result, peeling of the lead terminal 40 and cracking of the insulating base 10 can be suppressed.

Next, a heater according to another embodiment of the present disclosure will be described.

FIG. 4 is a cross-sectional view showing a heater according to another embodiment of the present disclosure. The cross-sectional view of FIG. 4 corresponds to the cross-sectional view shown in FIG.

The heater 1A of the present embodiment is different from the heater 1 of the above-described embodiment in the shapes of the insulating substrate 10 and the heating resistor 20, and is the same in the other respects. The description is omitted.

The heater 1A includes a cylindrical insulating substrate 10. The insulating base 10 has one end (hereinafter, also referred to as a first end) 11 and the other end (hereinafter, also referred to as a second end) 12 in the longitudinal direction (the horizontal direction in FIG. 4 ). The insulating substrate 10 may have a triangular tubular shape, a rectangular tubular shape, a cylindrical shape, an elliptic tubular shape, or the like, or may have any other shape. In the heater 1A of the present embodiment, the insulating base 10 has a cylindrical shape.

The insulating base 10 is made of an electrically insulating ceramic material. Examples of the ceramic material used for the insulating substrate 10 include ceramics having electrical insulation such as oxide ceramics, nitride ceramics, carbide ceramics, and silicon nitride ceramics. The insulating substrate 10 has, for example, a length in the longitudinal direction of 20 to 40 mm, an outer diameter of 2 to 8 mm, and an inner diameter of 1 to 5 mm.

The heating resistor 20 is provided inside the insulating base 10, and has an embedded portion 21 embedded in the insulating base 10 and an exposed portion 22 extended to the side surface 13 of the insulating base 10. The embedded portion 21 has a conductor pattern which is repeatedly folded along the circumferential direction of the insulating base 10 between a portion near the first end 11 and a portion near the second end 12. The exposed portion 22 is located near the second end 12 of the insulating base 10 as shown in FIG. 4, for example.

According to the heater 1A of the present embodiment, it is possible to reduce the stress concentration on the joint portion between the lead terminal 40 and the conductive layer 30, similarly to the heater 1 of the above embodiment. Further, according to the heater 1</b>A, similarly to the heater 1, it is possible to suppress the concentration of stress on a specific portion of the insulating substrate 10 and reduce the uneven temperature distribution at the joint between the lead terminal 40 and the conductive layer 30. The generation of thermal stress in the joint can be suppressed. Thus, according to the heater 1A of the present embodiment, it is possible to provide a heater having excellent durability.

Although the embodiments of the present disclosure have been described above in detail, the present disclosure is not limited to the above-described embodiments, and various modifications and improvements can be made without departing from the scope of the present disclosure. is there.

1, 1A heater 10 insulating substrate 11 one end (first end)
12 other end (second end)
13 side surface 20 heating resistor 21 embedded portion 21a parallel portion 21b bent portion 22 exposed portion 30

conductive layer

30a, 30b end portion 30c one end 30d other end 40 lead terminal 41 first portion 42 second portion 42a end portion 43 third portion

43a Edge part

50,60 Adhesive material 70 Cylindrical member

Claims

An insulating substrate that is rod-shaped or tubular and has one end and the other end;
A heating resistor provided inside the insulating base and drawn out to a side surface of the insulating base;
A conductive layer provided on a portion of the side surface where the heating resistor is drawn out,
A lead terminal electrically connected to the heating resistor via the conductive layer,
The lead terminal has a first portion joined to the conductive layer, and a second portion located closer to the one end side than the first portion,
The second portion is separated from the conductive layer, and the end portion of the second portion on the one end side is located on the other end side of the end portion of the conductive layer on the one end side. A heater characterized by.
The lead terminal further has a third portion located closer to the other end side than the first portion,
The third portion is separated from the conductive layer, and the end portion of the third portion on the other end side is located closer to the one end side than the end portion of the conductive layer on the other end side. The heater according to claim 1, wherein the heater is provided.
The heater according to claim 1 or 2, wherein an insulating adhesive material is provided between the conductive layer and the second portion.
The insulating base further includes a tubular member that surrounds at least a portion where the conductive layer is provided in a circumferential direction of the insulating base.
The heater according to any one of claims 1 to 3, wherein the inside of the tubular member is filled with an insulating adhesive material.