JPH09161957A - Manufacture of ceramic heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify the processes and suppress the costs by eliminating use of any core material and also provision of through holes. SOLUTION: A ceramic heater concerned 1 is composed of a resistance heating element 5 covered with insulative composition sheets 2a, 2b and an external connection terminal 6 exposed from the heating element, wherein the heater is manufactured by forming the heating element 5 and connection terminal 6 on surface of the first sheet 2a, followed by lamination of the second sheet 2b in such a way as covering the surface of the heating element 5. The resultant is wound into rod shape in such an arrangement that the second sheet 2b is positioned outside and subjected to a baking process, and thus an intended heater 1 is accomplished.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a ceramic heater.

[0002]

2. Description of the Related Art Ceramic heaters having various shapes have been known. 5 and 6 illustrate a ceramic heater 31 having a rod shape or a tubular shape. The ceramic substrate that constitutes the ceramic heater 31 is obtained by winding a ceramic sheet material 33 around a rod-shaped ceramic core material 32 and then firing it.
A resistance heating element 34 that generates heat when energized is formed inside the ceramic substrate. A pair of external connection terminals 35 are formed on the outer peripheral surface of one end of the ceramic base.
Are formed. Each external connection terminal 35 and resistance heating element 3
4 is connected via a through hole 36 penetrating the sheet material 33. A lead wire 37 is joined to each external connection terminal 35. And the lead wire 37
When the resistance heating element 34 is energized via the
Electrical energy is converted to thermal energy by 4,
The temperature of the ceramic substrate increases.

The ceramic heater 31 is
For example, sheet forming of the ceramic sheet material 33, perforation for forming the through holes 36, printing of a metal paste, winding of the sheet material on the ceramic core material 32, firing, plating on the external connection terminals 35, It is manufactured by undergoing a process such as brazing of the lead wire 37.

[0004]

However, the conventional method of manufacturing the ceramic heater 31 has the following problems.

First, in the ceramic heater 31, the resistance heating element 34 is formed on one side surface of the sheet material 33, and the external connection terminal 35 is formed on the opposite side surface thereof. Therefore, in order to connect the resistance heating element 34 and the external connection terminal 35 that do not exist on the same surface, the through hole 36
Must be formed. However, in order to obtain such a structure, it is necessary not only to perform steps such as punching and through-hole filling, but also to perform the metallic paste printing step a plurality of times. Therefore, the number of steps is increased and the configuration is complicated, resulting in high cost.

Secondly, when the ceramic heater 31 is manufactured, it is necessary to separately form the sheet material 33 and the core material 32 by using dedicated apparatuses. Therefore, it is disadvantageous in terms of the number of steps and cost.

In addition to the above-described manufacturing method, for example, after the resistance heating element 34 and the external connection terminal 35 are formed by directly printing a metallic paste on the outer peripheral surface of the core material 32, a ceramic paste or the like is formed. A method of forming an insulating layer by coating is conceivable. According to this method, since the resistance heating element 34 and the external connection terminal 35 are formed on the same surface, the through hole 36 is basically unnecessary.
Moreover, since the core material 32 is sufficient, the sheet material 33 is also unnecessary.

However, since the curved surface is printed by this method, it is difficult to form the resistance heating element 34 with high precision. That is, it becomes difficult to control the resistance value such that the thickness of the resistance heating element 34 varies. In addition, the thickness of the insulating layer tends to be uneven. Therefore, the resistance value of the ceramic heater 31 tends to be unstable.
In addition, a dedicated printing device is required to print on a curved surface, which may increase the cost.

The present invention has been made to solve the above problems. A first object of the present invention is that a core material and a through hole are not required, so that the process can be simplified and the cost can be reduced. Another object of the present invention is to provide a method of manufacturing a ceramic heater that can achieve the above. A second object of the present invention is to provide a method for manufacturing a ceramic heater that can easily and reliably stabilize the resistance value of the ceramic heater.

[0010]

In order to solve the above-mentioned problems, in the invention described in claim 1, the resistance heating element covered with the insulating composition sheet and exposed from the insulating composition sheet. A method of manufacturing a ceramic heater having an external connection terminal, comprising forming a resistance heating element and an external connection terminal on one surface of a first insulating composition sheet, and then forming a surface of the resistance heating element. Second to cover
The method of manufacturing a ceramic heater is characterized in that after laminating the insulating composition sheets described in 1 above, the second insulating composition sheets are rolled so as to be the outside and formed into a rod shape, and firing is performed.

According to a second aspect of the present invention, in the first aspect, the resistance heating element and the external connection terminal are flattened before the laminating step. According to a third aspect of the present invention, in the first or second aspect, the laminating step is performed after forming an adhesive layer on the surface on which the resistance heating element and the external connection terminal are formed.

Next, the "action" of the present invention will be described. According to the first aspect of the present invention, since the ceramic core material is not used, an apparatus for forming the core material such as an extrusion molding machine becomes unnecessary. Therefore, the equipment cost can be reduced by the amount that such a device is unnecessary.
Of course, steps such as molding, drying, and cutting of the core material are not necessary, so that the process simplification and cost reduction can be achieved accordingly. In addition, since the resistance heating element and the external connection terminal can be formed on the same surface, it is not necessary to perform a process such as drilling or filling a through hole in the sheet material unlike the conventional case. Therefore, the process can be simplified as compared with the conventional one, and the cost of the ceramic heater can be reduced.

Further, according to this manufacturing method, the resistance heating element and the external connection terminal are formed on the first insulating composition sheet which is flat, and after the second insulating composition sheet is laminated thereon. By winding, the whole becomes rod-shaped (or cylindrical). That is, since the surface on which the resistance heating element and the external connection terminal are to be formed is a flat surface, the inconvenience expected when the surface is a curved surface is also eliminated. Therefore,
The resistance heating element can be formed relatively accurately, and the resistance heating element is less likely to have a thickness variation. Therefore, the control of the resistance value is not so difficult, and the stabilization of the resistance value of the ceramic heater is achieved relatively easily. further,
Since no dedicated printing device is required, the facility cost can be reduced accordingly.

Further, according to this manufacturing method, for example, the first and second insulating composition sheets can be cut out from a continuous ceramic sheet material, so that the compositions of both can be made equal. . Therefore,
It is easy to match the firing shrinkage rates of both. Further, from this fact, cracks, warpage, etc. are less likely to occur at the interface between the first and second insulating composition sheets, and the yield is improved. Furthermore, according to the above method, only one ceramic raw material is required, which is convenient for simplifying the process and reducing the cost.

Further, according to this manufacturing method, the second insulating composition sheet laminated on one surface of the first insulating composition sheet becomes, so to speak, an insulating layer, and thereby formed on the same surface. The resistance heating element and the external connection terminal are insulated. The formation of the insulating layer by such a method is less likely to cause variations in the thickness of the insulating layer itself, as compared with the case of forming the insulating layer by coating a ceramic material or the like. Therefore, the outer surface of the ceramic heater is less likely to have irregularities, which leads to an improvement in appearance.

According to the second aspect of the present invention, since the resistance heating element and the external connection terminal are flattened before the laminating step, the lamination is performed after making their thickness uniform. . Therefore, it is possible to further stabilize the resistance value as compared with the case where stacking is performed in a state where the resistance heating elements have thickness variations.

According to the third aspect of the invention, the adhesive layer is formed on the surface on which the resistance heating element and the external connection terminal are formed, and then the lamination is performed. Therefore, the adhesion between the ceramic sheet materials is improved, and peeling hardly occurs at their interface. In addition, the surface of the ceramic heater is smoothed during sintering.

[0018]

DETAILED DESCRIPTION OF THE INVENTION A ceramic heater 1 according to an embodiment of the present invention will be described in detail below with reference to FIGS.

As shown in FIGS. 1 and 2, the ceramic heater 1 is formed by using the laminated sintered body 3 as a base. The laminated sintered body 3 is obtained by laminating a plurality of (three in the present embodiment) ceramic sheet materials 2a and 2b as insulating composition sheets and winding them to form a rod shape or a cylindrical shape. The laminated sintered body 3 obtained by sintering is formed as a base. The laminated sintered body 3 also has a central hole 4 extending in the longitudinal direction. In the laminated sintered body 3, a slit S1 communicating with the central hole 4 is formed between the sheet winding start end and the sheet winding end end. Therefore, the laminated sintered body 3 is not a perfect cylindrical shape but an incomplete cylindrical shape (because the cross section is substantially C-shaped). However, here, regardless of the presence or absence of such a slit S1 or the size thereof, it is understood as "cylindrical" or "rod".

In the laminated sintered body 3 of the present embodiment, the first ceramic sheet material 2a (hereinafter simply referred to as the first sheet material 2
Call a. ) Is used, and two second ceramic sheet materials 2b (hereinafter, simply referred to as second sheet materials 2b) are used. The former is a sheet material 2a for forming the resistance heating element 5 and the external connection terminal 6 on one side surface,
The latter is, so to speak, an insulating sheet material 2b for protecting the formed resistance heating element 5. The former is located on the inner side of the laminated sintered body 3, that is, on the side of the central hole 4.

In the case of this laminated sintered body 3, the area of the first sheet material 2a is slightly larger than that of the second sheet material 2b. Therefore, a part of the first sheet material 2a is
It projects from the base end side (that is, the right end side in FIG. 1). This protruding portion is the small diameter portion 3b of the laminated sintered body 3, and has a one-layer structure composed of only the first sheet material 2a. On the other hand, the part on the tip side of that is the first
The large-diameter portion 3a has a three-layer structure including the sheet material 2a and the second sheet material 2b.

First sheet material 2a and second sheet material 2b
An adhesive layer 9 is interposed at the interface between the second sheet material 2b and the second sheet material 2b. The ceramic contained in the adhesive used to form the adhesive layer 9 is preferably of the same type as the ceramic material used to form the first and second sheet materials 2a and 2b. The reason is to match the firing shrinkage of each ceramic. Therefore, the first and second
When the sheet materials 2a and 2b of (1) are made of alumina, it is preferable to similarly select an alumina adhesive.

The laminated sintered body 3 includes a resistance heating element 5 having a straight portion 5a and a meandering portion 5b. The two linear portions 5a are formed on the outer surface of the first sheet material 2a and extend along the longitudinal direction of the laminated sintered body 3. Further, most of the straight portion 5a belongs to the large diameter portion 3a, and the remaining portion belongs to the small diameter portion 3b. That is, the straight portion 5a
Is almost hidden under the second sheet material 2b. The meandering portion 5b, which is a substantial heat generating portion, is also formed on the outer surface of the first sheet material 2a, and meanders zigzag along the circumferential direction at the tip of the laminated sintered body 3. Further, the meandering portion 5b is completely hidden under the second sheet material 2b.

A pair of rectangular external connection terminals 6 are formed on the outer surface of the first sheet material 2a exposed in the small diameter portion 3b. The external connection terminals 6 and the exposed portions of the straight portions 5a are connected to each other on the outer surface of the first sheet material 2a. That is, the resistance heating element 5 and both external connection terminals 6 are electrically connected on the same surface. The ends of lead wires 7 made of a metal such as nickel are joined to both external connection terminals 6 by brazing. The base ends of these lead wires 7 project from the base end surface of the laminated sintered body 3.

On the surfaces of the external connection terminals 6 and the brazing material 8,
Electroless nickel plating (not shown) is applied to prevent metal oxidation and corrosion. The ceramic heater 1 does not use a ceramic core material as a base. In addition, the first and second sheet materials 2a,
In 2b, there is no through hole penetrating the front and back.

Electric current is supplied to the resistance heating element 5 from a power source (not shown) through the two lead wires 7 to the ceramic heater 1 thus constructed. Then, when the electric current passes through the resistance heating element 5 (particularly the meandering portion 5b), the electric energy is converted into thermal energy, and the temperature of the tip portion of the laminated sintered body 3 rises.

Next, the procedure for manufacturing the above-mentioned ceramic heater 1 will be described in detail. First, a sheet material 2 is formed using a ceramic material as a starting material and a doctor blade device, and then dried. Examples of the ceramic material for forming the sheet material 2 include alumina, aluminum nitride, mullite, steatite, cordierite and the like. In this embodiment, alumina is selected.

After the sheet drying step, a screen mask is set on the upper surface of the sheet material 2 and the squeegee is driven to screen-print the metallic paste on the portion which will later become the first sheet material 2a. As a result, the resistance heating element 5 including the straight line portion 5a and the meandering portion 5b and the external connection terminal 6 are simultaneously formed on one side surface of the sheet material 2. Here, as the metallic paste, a paste containing a refractory metal such as tungsten, molybdenum, tantalum, niobium, or titanium is used. In this embodiment, a tungsten paste is used.

The resistance heating element 5 and the external connection terminal 6 formed as described above are pressure-bonded by a uniaxial press machine or the like (flattening treatment). As a result of this flattening process, the resistance heating element 5
Also, the thickness of the external connection terminal 6 is made uniform, and the resistance value of the ceramic heater 1 (resistance heating element 5) is stabilized. The flattening method may be pressing with the uniaxial press as described above, or may be, for example, passing between a pair of parallel rollers.

Next, the sheet material 2 is cut into a rectangular shape and the first
Sheet material 2a. The second sheet material 2b is
It is obtained by cutting an area of the sheet material 2 where the metallic paste is not printed. That is, in the present embodiment, since the first sheet material 2a and the second sheet material 2b are cut out from one sheet material 2, both
The ceramic materials of a and 2b are completely the same in composition.

After the cutting step, an adhesive is applied, and first, two second sheet materials 2b are stacked on one first sheet material 2a. At this time, the first sheet material 2a
Of the metallic paste printed above, the external connection terminals 6
Only the second sheet material 2b is exposed, and the other portions are arranged below the second sheet material 2b. Then, the first and second sheet materials 2a and 2b are pressure-bonded to each other. As a result, a plate-shaped laminated sheet material obtained by integrating the above three sheets is obtained. Note that the laminating step may be performed in a heated state depending on the type of binder kneaded with the first and second sheet materials 2a and 2b.

In the molding step performed after the cutting step, the plate-shaped laminated sheet material is rolled to deform it into a tubular shape. In this case, the plate-shaped laminated sheet material is wound such that the external connection terminals 6 are the outer peripheral surface, that is, the first sheet material 2a side is the inner side. As a method of deformation by winding, for example, there is a method of winding the first and second sheet materials 2a and 2b around the core rod. In this case, it is preferable that the core rod is wound and heated to a lamination temperature or higher. With this method, the shape of the laminated sheet material is retained more firmly than in the case where heat is not applied. Here, in order to perform the above thermoforming, it is desirable that the binder is a thermosetting resin.

After that, the laminated sheet material wound in a tubular shape is fired in a non-oxidizing atmosphere to separate the first and second sheet materials 2a and 2b, the resistance heating element 5 and the external connection terminal 6. Unify. Further, after electroless nickel plating is performed as the primary plating on the surface of the external connection terminal 6, heat treatment is performed to improve the adhesion of the plating. Then
The lead wire 7 is brazed to the plated external connection terminal 6. After that, the brazing material 8 is subjected to electroless nickel plating as secondary plating, and then heat treated again. The ceramic heater 1 is obtained through the above procedure.

Hereinafter, the ceramic heater 1 of this embodiment
The characteristic actions and effects relating to the production method of are listed. (A) In the manufacturing method of the present embodiment, since the ceramic core material is not used, an apparatus for forming the core material such as an extrusion molding machine becomes unnecessary. Therefore, the equipment cost can be reduced by the amount that such a device is unnecessary. Of course, steps such as molding, drying, and cutting of the core material are not necessary, so that the process simplification and cost reduction can be achieved accordingly. Further, according to this method, the resistance heating element 5 and the external connection terminal 6 can be formed on the same surface, that is, on the outer surface of the first sheet material 2a. Therefore, unlike the prior art, there is no need to perform a process such as punching holes in the sheet material 2 or filling through holes. Therefore, the process can be simplified as compared with the related art, and the cost of the ceramic heater 1 can be reduced.

(B) In this embodiment, the resistance heating element 5 and the external connection terminal 6 are formed on the first sheet material 2a which is flat, and the second sheet material 2b is laminated on the resistance heating element 5 and the external connection terminal 6 and then wound. It is characterized by forming them into a tubular shape by attaching them. That is, since the surface on which the resistance heating element 5 and the external connection terminal 6 are to be printed is a flat surface, the inconvenience expected when the surface is a curved surface is eliminated. Therefore, since the resistance heating element 5 can be formed with relatively high accuracy, the resistance heating element 5 is less likely to have a thickness variation. Therefore, the control of the resistance value is not so difficult, and the stabilization of the resistance value of the ceramic heater 1 is achieved relatively easily. Further, since a dedicated printing device is unnecessary, the equipment cost can be reduced accordingly.

(C) In this manufacturing method, since the resistance heating element 5 and the external connection terminal 6 are flattened before the laminating step, the lamination is performed after making their thickness uniform. . Therefore, it is possible to further stabilize the resistance value as compared with the case where the resistance heating elements 5 are laminated in a state where the thickness varies.

(D) According to this manufacturing method, the sheet material 2
Since the first sheet material 2a and the second sheet material 2b are respectively cut out from the above, the compositions of both 2a and 2b are completely the same. Therefore, the firing shrinkage is matched as compared with the case of using ones having different compositions (such as ones containing different ceramic materials). For this reason, there is an advantage that cracks and warpage are less likely to occur at the interface between the two 2a and 2b, and the yield is improved. In addition, the fact that only one type of ceramic raw material is required also has a positive effect on process simplification and cost reduction.

(E) According to the manufacturing method of the present embodiment, the second sheet material 2b laminated on one side surface of the first sheet material 2a becomes, so to speak, an insulating layer, so that resistance heating formed on the same surface. The body 5 and the external connection terminal 6 are insulated. The formation of the insulating layer by laminating the second sheet material 2b is as follows.
For example, the degree of occurrence of thickness variation of the insulating layer itself is smaller than that of forming the insulating layer by applying a ceramic material or the like. Therefore, the outer surface of the ceramic heater 1 is unlikely to have irregularities, which leads to an improvement in appearance.

(F) According to this manufacturing method, the sheet material 2
Since the laminating step is performed after forming the adhesive layer 9 on a and 2b, each layer is firmly adhered via the adhesive layer 9. Therefore, due to the improved adhesion, peeling is less likely to occur at those interfaces, and as a result, the strength of the ceramic heater 1 is improved. Further, since the surface of the ceramic heater 1 is smoothed after sintering, its appearance can be improved.

The present invention can be modified as follows, for example. (1) The resistance heating element 5 and the external connection terminal 6 may be formed by thick film printing or the like using a metal mask. Of course, they may be formed using other film forming methods such as plating.

(2) The ceramic heater 21 according to another example 1 shown in FIGS. 3A and 3B may be manufactured by the following method. First, the steps up to the metallic paste printing step are performed according to the procedure of the above embodiment, and the sheet material 2
In step 1, the resistance heating element 5 and the external connection terminal 6 are formed in the portion that will later become the first sheet material 2a. In the subsequent cutting step, one sheet of the first sheet material 2a is cut out, and
Two second sheet materials 2b having substantially the same shape are cut out. At this time, slit-shaped notches 22 are formed at two positions on one end side of the second sheet material 2a, that is, on the side that will later become the base end portion of the laminated sintered body 3. Notch 22
Must be formed at a position just above the external connection terminal 6 when laminated. Further, three sheet materials 2a and 2b are laminated in the laminating step. Then
Only a part of the external connection terminal 6 is exposed from each cutout portion 22, and the other metallic paste printed portions are all hidden under the second sheet material 2b. After that, the ceramic heater 21 of FIG. 3 is obtained by performing the steps after firing according to the procedure of the above-described embodiment. In addition,
Since the ceramic heater 21 has a substantially equal cross-sectional shape, it has a characteristic that there is no portion to be called the large diameter portion 3b or the small diameter portion 3c. With this configuration, the notch 22
May be slightly difficult to manufacture because it is required to be provided at an accurate position. In this respect, the manufacturing method of the above embodiment is superior. However, in this ceramic heater 21, since the lead wire 7 is just inserted into the cutout portion 22, the lead wire 7 can be securely fixed to the same portion. Moreover, since the position where the lead wire 7 should be fixed can be easily grasped, the brazing work of the lead wire 7 becomes easier.

(3) In the step of cutting out the sheet materials 2a and 2b, without forming the cutout portion 22, only the ceramic material of the portion which will be the outer layer of the external connection terminal 6 is ground, and the external connection terminal 6 is cut therefrom. A method of exposing it is also possible. However, in view of the fact that a grinding step is newly required, it is considered that the manufacturing method of the embodiment that does not require such a step is somewhat advantageous. That is,
Compared with the above method in which the notch 22 is not formed,
In the above embodiment, the manufacturing cost of the ceramic heater 1 can be reduced and the manufacturing thereof can be facilitated more reliably.

(4) It is also possible to manufacture the ceramic heater 26 as in another example 2 shown in FIG. 4 by carrying out the laminating step without forming the adhesive layer 9 on the sheet materials 2a and 2b. .

(5) When the adhesive is used in the above embodiment, the adhesive layer 9 may be formed by printing, for example, an alumina paste instead of the alumina adhesive. In this case, an organic adhesive may be applied to the surface of the alumina paste.

(6) Ceramic heaters 1 and 2 of the present invention
The members 1 and 26 do not necessarily have to be wound in a cylindrical shape, and may be wound in an elliptic cylinder shape or a polygonal cylinder shape, for example.

Here, in addition to the technical ideas described in the claims, the technical ideas grasped by the above-described embodiments are listed below together with their effects. (1) The method for manufacturing a ceramic heater according to any one of claims 1 to 3, wherein the binder in the insulating composition sheet is a thermosetting resin. According to this method, for example, when the winding deformation work is performed in which the first and second insulating composition sheets are wound around the core rod and heated above the stacking temperature, the binder does not heat. Curing ensures that the deformed sheet shape is retained. Therefore, it is possible to further facilitate the production of the ceramic heater as compared with the case where the thermosetting resin is not used.

The technical terms used in this specification are defined as follows. "Metallic paste: A paste containing one or more refractory metals such as tungsten, molybdenum, tantalum, niobium, and titanium."

[0048]

As described above in detail, according to the inventions described in claims 1 to 3, since the core material and the through holes are not required, the process can be simplified and the cost can be reduced. A method of manufacturing a ceramic heater that can be achieved can be provided. Also, according to these methods,
Since the resistance value can be easily controlled and the resistance heating element and the like can be made uniform, the resistance value of the ceramic heater can be easily and reliably stabilized.

According to the second aspect of the present invention, since the resistance heating element and the external connection terminal are made uniform in thickness, it is possible to further stabilize the resistance value. Claim 3
According to the invention described in (1), peeling is less likely to occur due to improved adhesion at the interface of the insulating composition sheet, and as a result, the strength of the ceramic heater is improved. Also, the appearance of the ceramic heater can be improved.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a ceramic heater of the present embodiment.

2A is a sectional view taken along line AA of the ceramic heater shown in FIG. 1, and FIG. 2B is a sectional view taken along line BB.

FIG. 3A is a perspective view showing a ceramic heater of another example 1, and FIG. 3B is a sectional view taken along line CC of FIG.

FIG. 4 is a sectional view of a large-diameter portion of a ceramic heater according to a second example.

FIG. 5 is a perspective view showing a conventional ceramic heater.

6 is a cross-sectional view of the ceramic heater of FIG. 5 taken along the line D-D.

[Explanation of symbols]

1, 2, 26 ... Ceramic heater, 2a ... First ceramic sheet material as first insulating composition sheet, 2b ... Second ceramic sheet material as second insulating composition sheet, 5 ... Resistance heating element, 6 ... External connection terminal, 27 ... Adhesive layer.

Claims (3)

[Claims] 1. A method for producing a ceramic heater having a resistance heating element covered with an insulating composition sheet and an external connection terminal exposed from the insulating composition sheet, the method comprising a first insulating property. A resistance heating element and an external connection terminal are formed on one surface of the composition sheet, and then a second insulating composition sheet is laminated so as to cover the surface of the resistance heating element. A method for producing a ceramic heater, which comprises winding the composition sheet so that the sheet is on the outside, forming a rod shape, and firing. 2. The resistance heating element and the external connection terminal,
The method of manufacturing a ceramic heater according to claim 1, wherein the ceramic heater is flattened before the laminating step. 3. The method of manufacturing a ceramic heater according to claim 1, wherein an adhesive layer is formed on a surface on which the resistance heating element and the external connection terminal are formed, and then the laminating step is performed.