JP2006261014A - Connecting terminal jointing ceramic heater and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a connecting terminal jointing ceramic heater superior in exothermic performance and temperature control performance, capable of demonstrating a stable performance for a long period, and its manufacturing method. <P>SOLUTION: This is a connecting terminal jointing ceramic heater in which a jointing part jointing an electrode part which is provided on the surface of a ceramic substrate and connected electrically to a heater exothermic portion heated by current flow and a plate-shape part provided at the end part of a connector connected electrically to the outside is coated by a metallic layer. The metallic layer is formed with a thickness of 4 μm or more at the outer circumference edge of a face on the opposite side to the jointing face of the electrode part in the plate-shape part, and its manufacturing method is provided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a connection terminal bonded ceramic heater and a method for manufacturing the same, and more particularly, to prevent corrosion of a bonded portion obtained by bonding an electrode portion of a ceramic heater and a plate-like portion of a connection terminal, to stably generate heat, and to have a long life. The present invention relates to a connection terminal bonded ceramic heater and a method for manufacturing the same.

  Conventionally, a metal used as a ceramic-metal sintered joined body such as a ceramic heater is often a heat-resistant metal such as tungsten or molybdenum. Among these metals, tungsten-based metals are familiar with alumina and have excellent heat resistance, so they are electrically connected to a heater provided inside an alumina ceramic substrate and provided on the surface of the ceramic substrate. Often used as an electrode section. In this case, a lead wire connection terminal or the like that is electrically connected to the outside by brazing or the like is attached to the electrode portion to form a joint portion. As the connection terminal, a highly conductive metal such as nickel is used. At this time, in order to join the connection terminal made of nickel or the like to the tungsten electrode portion provided on the ceramic substrate, the surface of the electrode portion such as tungsten is plated with nickel, and the formed nickel plating film is silver-copper. A method of brazing connection terminals using a brazing material made of an alloy such as copper-gold or copper-silver has been adopted. The reason why the nickel plating film is applied to the electrode portion in advance is to improve the wettability between the tungsten-based electrode portion and the brazing material containing copper, silver and the like. After that, since the brazing material containing copper, silver, etc. is easily corroded, a nickel layer is applied again to the joint after brazing, and a metal layer is formed to prevent corrosion of the brazing material and brazed joint. Yes.

  Conventionally, problems are likely to occur at the joint between the electrode portion of the ceramic heater and the connection terminal, and various improvements have been attempted. Patent Document 1 discloses a ceramic heater in which a sulfur content in a nickel plating film formed on an electrode portion is limited to prevent conduction failure due to peeling of a joint surface between the electrode portion and a connection terminal. Patent Document 2 reports a ceramic-metal bonded body that can be suitably used for a ceramic heater using a copper-gold-nickel brazing material having a specific composition in consideration of the bonding strength and economic efficiency of the bonded portion. Yes.

Japanese Unexamined Patent Publication No. Hei 8-185956 JP 11-292649 A

  However, among such ceramic heaters, many joints are very easily corroded, and many electrode heaters have poor conductivity and are subject to reliability of heat generation control. In recent ceramic heaters for sensors and the like, strict heat generation management is required, and poor conductivity or instability of the electrode part leads to poor heater heat generation performance, and consequently poor temperature control, and can be disabled immediately. An object of the present invention is to provide a connection terminal bonded ceramic heater capable of exhibiting stable performance for a long time without such trouble and a method for manufacturing the same.

The connection terminal bonded ceramic heater described above is a plate-shaped portion having a plate shape in which the end portion of the connection terminal bonded to the electrode portion of the ceramic heater has a substantially square cross section. According to the study by the present inventors, when the metal part such as plating is coated on the joint part obtained by joining the plate part to the electrode part of the ceramic heater, the side opposite to the joint surface with the electrode part of the plate part It has been found that it is difficult to form a metal layer having a sufficient thickness on the outer peripheral edge, which is a corner portion of this surface (hereinafter also referred to as the opposite side surface), compared to other portions such as a flat portion on the opposite side surface. Due to the long-term use of the ceramic heater, the brazing material and the connection terminal near the outer peripheral edge of the opposite side surface where the coated metal layer is not sufficient are exposed. It was found that poor conductivity occurred.

The present inventors have found a means for solving the following problems based on the above knowledge.
(1) Joining the electrode part provided on the surface of the ceramic substrate and electrically connected to the heater heating part that generates heat when energized and the plate-like part provided at the end of the connection terminal electrically connected to the outside In the connection terminal bonding ceramic heater in which the bonded portion is covered with a metal layer, the metal layer has a thickness of 4 μm or more on the outer peripheral edge of the surface of the plate-like portion opposite to the bonded surface of the electrode portion. It is a connection terminal joining ceramic heater characterized by being formed.
(2) The connection terminal bonding according to (1), wherein a protrusion having a length of 10 μm or more and a thickness of 300 μm or less and a length / thickness ratio of ½ or more is not formed on the outer peripheral edge of the plate-like portion. Ceramic heater.
(3) The connecting portion is the connecting terminal bonded ceramic heater according to (1) or (2), in which the electrode portion and the plate-like portion of the connecting terminal are bonded with a brazing material.
(4) The connection terminal bonded ceramic heater according to any one of (1) to (3), wherein the metal layer is a metal plating layer containing at least one of nickel, gold, silver, and platinum.
(5) The electrode portion provided on the surface of the ceramic base and electrically connected to the heater heat generating portion that generates heat when energized is joined to the plate-like portion provided at the end of the connection terminal electrically connected to the outside. In the manufacturing method of the connecting terminal bonded ceramic heater in which the bonded portion is coated with a metal layer,
The plate-like portion of the connection terminal is created by punching a plate material, and the surface of the plate-like portion of the connection terminal in the punching direction is joined as a joint surface with the electrode portion to form the joint portion. This is a method of manufacturing a connection terminal bonded ceramic heater in which the surface of the part is covered with the metal layer having a thickness of 4 μm or more.
(6) The electrode portion provided on the surface of the ceramic base and electrically connected to the heater heat generating portion that generates heat when energized is joined to the plate-like portion provided at the end of the connection terminal electrically connected to the outside. In the manufacturing method of the connecting terminal bonded ceramic heater in which the bonded portion is coated with a metal layer,
The outer peripheral edge of the surface of the plate-like part to be joined to the electrode part opposite to the joining surface with the electrode part has a length of 10 μm or more and a thickness of 300 μm or less and a length / thickness ratio of 1/2 or more. After connecting the electrode part and the connection surface of the connection terminal, the connection part is formed, and the surface of the connection part is covered with a metal layer having a thickness of 4 μm or more. It is a manufacturing method of a joining ceramic heater.

  In the connection terminal bonded ceramic heater of the present invention, the metal layer is formed at a thickness of 4 μm or more on the outer peripheral edge of the opposite side surface of the plate-like portion. In this way, by providing a metal layer with a thickness of 4 μm or more on the outer peripheral edge of the opposite side surface of the plate-like portion that is a corner portion, even if the ceramic heater is used for a long period of time, it is suppressed that the joint portion is exposed, It is possible to suppress the corrosion of the joint and the conductive failure of the electrode part. Therefore, it can be set as the ceramic heater which can exhibit the performance stabilized for a long period of time. In addition, when the thickness of a metal layer is less than 4 micrometers, the said effect cannot be acquired.

  In the present invention, “the metal layer is formed at a thickness of 4 μm or more on the outer peripheral edge of the surface of the plate-like portion opposite to the bonding surface of the electrode portion” means the thickness of the plate-like portion. This means that when a cross section in the direction is taken and a virtual line passing through the corner corresponding to the outer peripheral edge of the plate-like part is drawn, the distance of the virtual line corresponding to the metal layer is 4 μm or more.

  For example, FIG. 3 and FIG. 4 show structural examples of the connection terminal bonded ceramic heater of the present invention. FIG. 3 shows an example of a cylindrical connection terminal bonded ceramic heater 1, which can be used in an environment where the temperature condition and the atmospheric gas are poor in a small precision instrument such as a sensor. The connection terminal bonded ceramic heater 1 mainly includes a ceramic heater 100 and a connection terminal 7. The ceramic heater 100 includes a cylindrical ceramic base 2 mainly composed of alumina or the like, and a heater heating portion 6 that generates heat by energization and a heater lead portion 3 (see FIG. 1) connected to the heater heating portion 6 in order from the tip side. It is buried (dotted line part). An electrode portion 4 is provided on the surface on the rear end side of the ceramic substrate 2. The electrode part 4 is connected to the heater lead part 3 through a conduction part 5 (see FIG. 1). The connection terminal 7 is joined to the electrode portion 4. As shown in FIG. 5, the connection terminal 7 is connected to a plate-like portion 8 connected to the electrode portion 4 formed at the front end portion and a lead wire (not shown) formed at the rear end portion. It consists of a caulking portion 15 and a connecting portion 16 that connects the plate-like portion 8 and the caulking portion 15. On the other hand, FIG. 4 shows an example of a flat connection terminal bonded ceramic heater 20 that can be used as a relatively large heater requiring severe temperature control, such as a semiconductor manufacturing apparatus. 4 has the same configuration as the connection terminal bonded ceramic heater 1 of FIG. 3 except that the shape of the ceramic substrate 22 is a flat plate.

  The connecting terminal bonded ceramic heater 1 of the present invention prevents deterioration due to corrosion or the like of the bonded portion where the electrode portion 4 and the plate-like portion 8 of the connecting terminal 7 are bonded, and this bonded portion will be described in detail. FIGS. 1 and 2 show a joint portion of the connection terminal joint ceramic heater of FIG. The electrode part 4 is exposed on the surface of the ceramic substrate 2 and is connected to the heater lead part 3 through the conduction part 5. A bonding surface 12 of the plate-like bonding portion 8 of the connection terminal 7 is bonded to the surface of the electrode portion 4 via a brazing material portion 9. The brazing material portion 9 uses a brazing material such as gold brazing, silver brazing, or copper brazing. For bonding, theoretically, bonding is possible if a brazing material exists only between the electrode portion 4 and the bonding surface 12 of the connection terminal 7. However, in the case of actual brazing, FIG. 1. As shown in FIG. 2, a brazing material portion 9 is formed so as to cover almost the entire plate-like joint portion 8 on the electrode portion 4 and the connection terminal 7. Since the brazing material portion 9 includes a metal that easily corrodes such as copper, the brazing material portion 9 is covered with a metal layer 10 such as nickel together with the electrode portion 4 and the plate-like portion 8 of the connection terminal 7. The metal layer 10 prevents the brazing material portion 9 from being corroded.

  The connecting terminal bonding ceramic heater 1 has a metal layer 10 covering the entire surface of the bonding portion constituted by the electrode portion 4, the connection terminal 7 (plate-like portion 8) and the brazing material portion 9, and the brazing material portion 9 is isolated from the outside. It is a structure. And this metal layer 10 is 4 micrometers or more in thickness t1 in the outer periphery 13 of the opposite side surface 14. FIG. The thickness t1 is preferably 6 μm or more, more preferably 8 μm or more. Thus, by providing the metal layer 10 having a thickness of 4 μm or more on the outer peripheral edge 13 of the opposite side surface 14 of the plate-like portion 8, even if the ceramic heater 1 is used for a long time, it is possible to prevent the joint portion from being exposed. In addition, corrosion of the joint portion and poor conductivity of the electrode portion 4 can be suppressed. Therefore, it can be set as the ceramic heater which can exhibit the performance stabilized for the period.

  By the way, in order to easily and efficiently manufacture the plate-like portion of the connection terminal, for example, it may be made by punching a plate material. At the time of punching, cutting residue, that is, burrs (hereinafter also referred to as protrusions) and scratches occur on the outer peripheral edge of the surface (hereinafter referred to as the surface in the punching direction) in contact with the table on which the plate material is placed. Sometimes. These burrs and scratches vary depending on the punching method and punching device, but it is difficult to eliminate them at all. In particular, burrs and scratches with a size of several μm to several tens of μm are likely to occur. Usually, such a size is difficult to detect with the naked eye. And if such a connection terminal is joined as it is to the electrode part of the ceramic heater to form a joint, a projection or a scratch may be formed on the outer peripheral edge 13 on the opposite side surface of the upper part of the connection terminal. Some brazing materials may not be corrected. Even if the bonding portion is covered with the metal layer as it is, it may be difficult to form a metal layer having a thickness of 4 μm or more on the protrusions and scratches.

  Therefore, the connection terminal bonded ceramic heater of the present invention is a protrusion having a length / thickness ratio of 1/2 or more on the outer peripheral edge 13 on the opposite side surface of the plate-like portion of the connection terminal, having a length of 10 μm or more and a thickness of 300 μm or less. It is preferable that there is no. In other words, since there are no protrusions or scratches having a specific range of size on the outer peripheral edge of the opposite side surface of the plate-like portion, a metal layer having a thickness of 4 μm or more can be easily formed on the outer peripheral edge. If the protrusion is small enough not to meet the above-mentioned conditions, it can be easily covered with a metal layer having a thickness of 4 μm or more. Further, even a flat protrusion exceeding the above condition can easily cover a metal layer having a thickness of 4 μm or more. It is preferable that there are no protrusions having a length of 5 μm or more and a thickness of 300 μm or less and a length / thickness ratio of 1/2 or more.

  For example, referring to FIGS. 1 and 2, the connecting terminal bonded ceramic heater 1 is disposed on the outer peripheral edge 13 of the opposite side surface 14 of the plate-like portion 8, such as the corner portion 11 of FIG. 1 or the boundary portion 17 of FIG. 2. This is a connecting terminal-bonded ceramic heater 1 having a length of 10 μm or more and a thickness of 300 μm or less and no protrusion having a length / thickness ratio of 1/2 or more. The connecting terminal bonded ceramic heater 1 having a smooth outer peripheral edge 13 without a protrusion having a specific size on the outer peripheral edge 13 of the opposite side surface 14 of the plate-like portion 8 has a thickness of 4 μm or more. Can be easily formed on the outer peripheral edge 13 of the opposite side surface 14 of the plate-like portion 8, and the metal layer on the protruding portion is worn or damaged during the handling or use of the connection terminal bonding ceramic heater 1. The brazing material will not be exposed. If the outer peripheral edge 13 has a protrusion having a length of 10 μm or more and a thickness of 300 μm or less and a length / thickness ratio of 1/2 or more, that is, a thin and relatively long protrusion, this is easily damaged and the brazing material is damaged. If it is exposed, corrosion starts from this part. However, if the protrusion is small enough not to meet the above-mentioned conditions, it is generally regarded as smooth, and if it is covered with a corrosion-resistant metal layer, it is hardly damaged. On the other hand, a large or nearly flat protrusion exceeding the above conditions is not easily damaged and does not cause a problem.

  The material of the member used for the connection terminal bonded ceramic heater of the present invention will be described. In principle, each member may be made of any material as long as it is selected according to the purpose of use of the ceramic heater. Generally preferable members will be described. As the ceramic substrate for the ceramic heater, alumina, silica, calcia, magnesia, silica alumina, mullite and the like are usually used. In addition, silicon nitride, silicon carbide, zirconia, sialon, boron nitride, calcium silicate, or the like may be used. Since alumina is usually easy to use, alumina is often used. Tungsten, molybdenum, or alloys thereof are used for the heater heating element, the electrode pads, and the conductive portions connecting them. In some cases, an alloy of nickel, platinum, or gold may be used. These parts have appropriate electrical conductivity and are fired integrally with the ceramic substrate, so that heat resistance is also required. Also, a metal that can be easily formed by printing or the like on a ceramic substrate before firing as a thin metal pad or the like is preferable. Tungsten does not have good adhesion to copper, which is a component of the brazing material, so the electrode part that joins the adhesive terminal is treated with nickel plating, gold plating, etc. after firing to improve the adhesion of the brazing material to the adhesive terminal. It is preferable to do. The electrode part and the connection terminal may be bonded by brazing or welding. Usually, brazing with a brazing material that is easy to operate and has sufficient adhesiveness is used. Although welding may be used, in this case, a portion that is melted by welding instead of the brazing material described above and is solid-solved with a welding agent such as a welding rod may be considered as a brazing material. The connection terminal may also be a normal connection terminal material. A metal such as copper, gold, silver, platinum, nickel, and aluminum having good electrical conductivity, heat resistance, corrosion resistance, and adhesiveness to the brazing material may be selected. Nickel is often preferred from the viewpoint of economy and corrosion resistance. The metal layer is often a plated layer. In particular, nickel plating, gold plating and the like are suitable. This layer may have any function as long as it mainly has a function of protecting the internal brazing material or the electrode portion and the connection portion of the connection terminal from corrosion.

  Next, the manufacturing method of the connection terminal joining ceramic heater of this invention is demonstrated. The manufacturing method of the ceramic heater according to the present invention is such that the plate-like portion of the connection terminal is created by punching a plate material, and the surface in the punching direction of the plate-like portion of the connection terminal is used as a joint surface with the electrode portion of the ceramic heater. And a ceramic heater electrode part are formed, and the surface of the joint part is coated with a metal layer having a thickness of 4 μm or more. The surface in the punching direction of the plate-like portion of the connection terminal is the surface in contact with the base on which the plate material is placed during punching, and refers to the surface where cutting residue, that is, burrs are likely to occur at the cut portion of the connection terminal. . As described above, when the connection terminal is made by punching a plate material, a protrusion or a scratch may occur on the outer peripheral edge of the surface in the punching direction. On the other hand, there are few protrusions or scratches on the surface opposite to the surface in the punching direction. Therefore, by setting the surface in the punching direction as the joint surface with the electrode portion, the outer peripheral edge on the opposite side surface of the plate-like portion is free from protrusions and scratches having a specific range size as described above. A metal layer can be easily formed on the outer periphery thereof.

  For example, a method for manufacturing a ceramic heater having a tungsten alloy heater heating section 6, heater lead section 3, electrode section 4 and conduction section 5 on an alumina substrate having the structure shown in FIG. Mold. A heater heating part 6 and a heater lead part 3 made of tungsten alloy are formed on one side of one alumina plate. Further, a small hole for conduction connected to the heater lead portion 3 is formed in the alumina plate, and the conduction portion 5 is created. And the electrode part 4 is formed in the surface opposite to the heater heat generating part 6 formation surface of an alumina plate. The electrode part 4 and the conduction part 5 are electrically connected. The heater heat generating portion 6 and the heater lead portion 3 are made of a tungsten alloy that has a desired electric resistance, and the conductive portion and the electrode portion are formed in a desired shape by printing or the like using a highly conductive tungsten alloy. On this, another alumina plate prepared separately is laminated so as to sandwich the surface on which the heater heat generating portion 6 and the heater lead portion 3 are formed, and is pressed into one alumina plate. If this unfired alumina plate is dried and then fired at a temperature of about 1200 ° C., a ceramic heater 20 as shown in FIG. 4 is obtained. Further, a ceramic heater 100 as shown in FIG. 3 can be obtained by rolling an unfired alumina plate on an alumina cylinder, forming it, and firing it. After firing, the surface of the electrode part 4 is preferably plated with nickel to facilitate brazing.

  On the other hand, the connection terminal 7 may be made using the conductive material as described above, but is preferably made of nickel, for example. It can be manufactured by punching out from a thin nickel plate with a mold matched to the shape of the connection terminal 7 and molding as shown in FIG. A plate-like portion 8 is formed at the end of one connection terminal 7. On the other hand, a caulking portion 15 is formed at a portion to be connected to the lead wire. For example, a U-shaped cross section as shown in FIGS. 3 and 4 may be used so that the lead wire can be easily connected by crimping. This portion may be a cylinder or a flat plate, and may be appropriately formed according to the purpose of use.

  Then, the plate-like portion 8 of the connection terminal 7 is joined to the electrode portion 4 of the ceramic heater. It should be noted that the bonding surface 12 of the connection terminal 7 with the electrode portion 4 is a surface in the punching direction. As a result, protrusions such as burrs generated on the surface in the punching direction of the connection terminals 7 during punching are buried in the brazing material part 9, and protrusions due to punching burrs appear on the surface opposite to the joint surface 12. Absent. Bonding may be performed by a method having strength and conductivity. Usually, brazing or welding is used, but it is preferable because brazing is simple and reliable. The brazing material described above may be used. For example, a silver-copper alloy silver solder may be used. Usually, the brazing material can be completely joined by welding the brazing material not only to the joint surface but also to the entire joint around the joint surface 12 as shown in FIGS.

  When the connection of the connection terminal 7 is finished, the entire joint is covered with the metal layer 10 having a thickness of 4 μm or more. At this time, protrusions and scratches are less likely to occur on the surface opposite to the surface in the punching direction (joint surface 12). As a result, the outer peripheral edge 13 of the side surface 14 opposite to the joint surface 12 is free from protrusions and scratches having the above-mentioned specific range, so that the metal layer 10 having a thickness of 4 μm or more can be easily formed on the outer peripheral edge 13. it can. As described above, nickel plating or the like can be suitably applied to the metal layer 10.

  As another method for manufacturing the connecting terminal bonded ceramic heater of the present invention, the outer peripheral edge of the surface opposite to the bonding surface with the electrode portion of the plate portion bonded to the electrode portion of the ceramic heater is 10 μm long. After the thickness is 300 μm or less and the protrusion having a length / thickness ratio of ½ or more is not present, the joined portion of the ceramic heater electrode portion and the connecting terminal is joined to form a joined portion. There is a manufacturing method in which the surface of the substrate is coated with a metal layer having a thickness of 4 μm or more. In this way, before the coating with the metal layer, the above-mentioned protrusions are not formed on the outer peripheral edge of the opposite side surface of the plate-like portion, the plating layer is easily formed uniformly, and the coating can be performed with the metal layer having a thickness of 4 μm or more. . Any method may be used to remove the protrusion formed on the outer peripheral edge 13 of the opposite side surface 14 of the plate-like portion, but it can be easily achieved by polishing the connection terminal by brushing, barrel polishing, grinding or the like. Of course, the connection terminals may be made by a manufacturing method that does not allow small projections from the beginning, such as forging.

In the ceramic heater of the present invention, the outer peripheral edge of the surface of the connection terminal opposite to the bonding surface with the electrode portion is coated with a metal layer of 4 μm or more, and there is no protrusion that is easily damaged. Therefore, the bonding material such as the brazing material used at the time of bonding the electrode portion and the connection terminal is not exposed and corroded on the surface. For this reason, there is no poor conduction at the joint, and stable current control can be performed, so that the ceramic heater has a high accuracy and a long life. Further, the fact that there is no protrusion at the joint does not cause the protrusion to damage other heaters or parts even if they are overlapped with other ceramic heaters at the time of manufacture or touch other parts at the time of use. The method for manufacturing a connection terminal bonded ceramic heater according to the present invention is a method for manufacturing a connection terminal bonded ceramic heater having a stable performance and a long life without increasing the manufacturing cost as compared with the conventional manufacturing method.

  The best mode for carrying out the present invention will be described with reference to examples and comparative examples.

Example 1
A raw material powder composed of 93 wt% alumina, magnesia, silica and calcia and 7 wt% sintering aid was made into a slurry in an ethanol solvent, and a flat plate having a thickness of 1.5 mm was made from this slurry by the doctor blade method. From this, a green sheet was prepared by punching into a plate shape having a length of 60 mm and a width of 10 mm. Two small holes on the green sheet were formed, and a heater pattern was printed on one side with a metal paste mainly composed of tungsten with the two small holes as a starting point. In addition, the small holes were filled with a metal paste to ensure conductivity with the heater pattern, and an electrode portion was formed with the metal paste in the small hole portion on the opposite surface of the green sheet. Ethanol is applied to the heater pattern side of the green sheet on which the heater pattern is formed, and a separately prepared cylindrical sintered body having a length of 60 mm, an outer diameter of 10 mm, and an inner diameter of 2 mm with the heater pattern side inward. Wrap around. This was fired at 1200 to 1300 ° C. in a firing furnace to produce a ceramic heater 100. Further, the electrode portion 4 of the ceramic heater 100 was subjected to nickel plating.

  On the other hand, a small piece having a length of 15 mm, a width of 1 mm, and a tip swelled into a substantially T shape was formed by punching from a 0.2 mm nickel plate. A U-shaped crimping portion 15 is formed by bending both side portions of the T-shape of this small piece in the same direction at 90 ° C. and crimping the lead wire, and the other end is joined to the electrode portion 4 of the ceramic heater 1. The connection terminal 7 having the shape shown in FIG. 5 was created as a connecting portion 16 whose middle portion was bent in a substantially staircase shape so as to be 8. At this time, the joint surface 12 of the plate-like portion 8 of the connection terminal 7 is made to be a surface in the punching direction. Then, the plate-like portion 8 of the connection terminal 7 is joined to the electrode portion 4 of the ceramic heater 1 by brazing with silver solder. When the brazing is complete, the metal layer 10 is formed by performing nickel plating, and the connection terminal bonded ceramic heater 1 of the present invention as shown in FIG. 3 is completed.

  The photograph which observed the plate-shaped part 8 of the connection terminal 7 of this connection terminal joining ceramic heater 1 with the electron microscope is shown in FIG. The upper diagram is a portion where the end of the plate-like portion 8 of the connection terminal 7 is joined to the electrode portion 4 of the ceramic heater 100. The lower figure is an enlarged view of the vicinity of the corner portion 11 indicated by the circle in the upper figure. As can be seen from the drawing, no protrusions having a height exceeding 5 μm or 10 μm are found on the outer peripheral edge 13 of the opposite side surface 14 of the plate-like portion 8.

  An upper part of FIG. 7 is an electron micrograph obtained by cutting the connection terminal 7 in the thickness direction and further enlarging and processing the reflected electron image by the energy dispersion method. The figure below shows this element mapping. In the vicinity of the outer peripheral edge 13 of the opposite side surface 14 of the plate-like portion 8, nickel of the connection terminal 7 base material, copper of the brazing material portion 9, silver, and nickel of the metal layer 10 are clearly layered in this order. FIG. 8 is a further enlarged element mapping diagram, and it is easier to understand that the outer metal layer 10 forms a layer having a thickness of 5 μm or more.

(Example 2)
When the connection terminal 7 was prepared in Example 1, the plate-like portion 8 of the connection terminal 7 was polished by barrel polishing to remove small protrusions. Using this polished connection terminal 7, the connection terminal bonded ceramic heater 1 of the present invention was produced in the same manner as in Example 1 except that the surface in the punching direction was changed to the side surface 14 opposite to the bonded surface 12. When observed with an electron micrograph in the same manner as in Example 1, the outer peripheral edge of the opposite side surface 14 of the plate-like portion 8 had a length of 10 μm or more and a thickness of 200 μm or less and a length / thickness ratio of 1/2 or more. There was no protrusion. Further, even when observed by element mapping, the metal layer 10 formed a layer having a thickness of 4 μm or more.

(Comparative example)
Instead of using the connection terminal subjected to barrel polishing in Example 2, a connection terminal bonded ceramic heater was prepared in the same manner as in Example 2 except that the connection terminal before barrel polishing was used.

(Evaluation by accelerated test)
The connection terminal bonded ceramic heaters 1 of Example 1, Example 2 and Comparative Example created above were evaluated by the following sulfurous acid gas aeration test. In a container of approximately 1 liter, the connecting terminal bonding ceramic heater for measurement and about 100 mg of sulfur are put apart, and the sulfur is ignited to seal the container and burn the sulfur. After 40 seconds, the connecting terminal bonded ceramic heater 1 is taken out of the container and the bonded portion is observed. The part where there is no nickel plating and the brazing material is exposed turns black. It is thought that silver became silver sulfide and blackened. In addition, when the nickel plating layer which should be clear white is sulfided and the whole is intensely black, the exposure time to sulfurous acid gas is shortened.

  As a result of the sulfurous acid gas aeration test, the connection terminal bonded ceramic heater of the present invention prepared in Example 1 and Example 2 had almost no blackened part including the edge and apex part of the plate-like bonded part of the connection terminal. On the other hand, it was considered that the connecting terminal bonded ceramic heater prepared in the comparative example had blackened portions at the ridges and apex portions of the plate-like bonded portions of the connecting terminals, and the brazing material was exposed. This brazing material contains copper, and if it is exposed to the outside, it is considered that corrosion starts easily from here.

  The connection terminal bonded ceramic heater of the present invention has a wide range of applications as a long-life and highly reliable heater that accurately controls temperature under severe conditions such as high temperatures and corrosive atmospheres, such as heaters for sensors and heaters for semiconductor manufacturing.

FIG. 1 is a structural diagram of a joint portion between a ceramic heater and a connection terminal in the connection terminal joint ceramic heater of the present invention. The upper circle is an enlarged view of the corner. FIG. 2 is a structural diagram of the cylindrical connecting terminal bonded ceramic heater of the present invention in a state where the cylinder of the connecting portion between the ceramic heater and the connecting terminal is cut into a ring. FIG. 3 is a view showing an example of the connecting terminal bonding ceramic heater of the present invention having a cylindrical shape. FIG. 4 is an exemplary view of a plate-like connecting terminal bonding ceramic heater according to the present invention. FIG. 5 is an exemplary view of connection terminals for the connection terminal bonded ceramic heater of the present invention. FIG. 6 is an electron micrograph of a part of the joint between the ceramic heater and the connection terminal of the connection terminal bonding ceramic heater of the present invention. The lower figure is an enlarged photograph of the apex portion of the plate-like joint part circled in the upper figure. FIG. 7 is an electron micrograph of a vertical cut surface at the ridge portion on the side surface opposite to the bonding surface of the connection terminal of the connection terminal bonding ceramic heater of the present invention. This corresponds to the corner portion 11 of the connection terminal in FIG. The upper figure is an electron micrograph obtained by processing a reflected electron image by the energy dispersion method, and the lower figure is a diagram obtained by element mapping. FIG. 8 is an enlarged view of the element mapping diagram of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,20: Connection terminal joining ceramic heater t1: Thickness of the metal layer formed in the corner part 2, 22: Ceramic base | substrate 3: Heater lead part 4: Electrode part 5: Conduction part 6: Heater heat generating part 7: Connection terminal 8: Plate-shaped part 9: Brazing material part 10: Metal layer 11: Corner part 12: Joining surface 13: Outer peripheral edge 14 of opposite side surface 15: Reverse side surface 15: Caulking part 16: Connection part 17: Boundary part 100: Ceramic heater

Claims (6)

  A joint provided on the surface of the ceramic base and joining the electrode part electrically connected to the heater heating part that generates heat when energized and the plate-like part provided at the end of the connection terminal electrically connected to the outside In the connecting terminal bonding ceramic heater coated with a metal layer, the metal layer is formed with a thickness of 4 μm or more on the outer peripheral edge of the surface of the plate-like portion opposite to the bonding surface of the electrode portion. A connecting terminal bonded ceramic heater.   2. The connection terminal bonded ceramic heater according to claim 1, wherein a protrusion having a length of 10 μm or more and a thickness of 300 μm or less and a length / thickness ratio of 1/2 or more is not formed on the outer peripheral edge of the plate-like portion.   The connection terminal bonded ceramic heater according to claim 1, wherein the bonding portion is formed by bonding the electrode portion and the plate-shaped portion of the connection terminal with a brazing material.   The connection terminal bonded ceramic heater according to claim 1, wherein the metal layer is a metal plating layer containing at least one of nickel, gold, silver, and platinum. There is a joined portion obtained by joining an electrode portion that is provided on the surface of the ceramic substrate and is electrically connected to a heater heat generating portion that generates heat when energized and a plate-like portion provided at an end portion of a connection terminal that is electrically connected to the outside. In the method of manufacturing a connection terminal bonded ceramic heater coated with a metal layer,
The plate-like portion of the connection terminal is created by punching a plate material, and the surface of the plate-like portion of the connection terminal in the punching direction is joined as a joint surface with the electrode portion to form the joint portion. A method of manufacturing a connection terminal bonded ceramic heater in which the surface of the portion is covered with the metal layer having a thickness of 4 μm or more. There is a joined portion obtained by joining an electrode portion that is provided on the surface of the ceramic substrate and is electrically connected to a heater heat generating portion that generates heat when energized and a plate-like portion provided at an end portion of a connection terminal that is electrically connected to the outside. In the method of manufacturing a connection terminal bonded ceramic heater coated with a metal layer,
The outer peripheral edge of the surface of the plate-like part to be joined to the electrode part opposite to the joining surface with the electrode part has a length of 10 μm or more and a thickness of 300 μm or less and a length / thickness ratio of 1/2 or more. After connecting the electrode part and the connection surface of the connection terminal, the connection part is formed, and the surface of the connection part is covered with a metal layer having a thickness of 4 μm or more. Manufacturing method of bonded ceramic heater.

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