Ceramic sealing component and method for manufacturing same

Abstract

A ceramic sealing component according to an embodiment is obtained by bonding a ceramic component and a nickel-plated metal component to each other by means of a bonding layer containing silver, copper, an active metal, and a low-melting-point metal. A compound of nickel and the active metal is formed in the bonding layer. The distance between the compound and the surface of the bonding layer is 10 μm or greater. A method for manufacturing a ceramic sealing component according to an embodiment comprises: a step for obtaining an active metal paste printed component by printing and drying, on a ceramic component, an active metal paste containing at least copper, an active metal, and a low-melting-point metal; a step for obtaining a brazing material paste printed component by printing and drying a brazing material paste containing at least silver and copper onto the surface of the active metal paste printed component; and a bonding step for installing a metal component on the brazing material paste printed component and subjecting the result to heat treatment.

Description

Ceramic sealing parts and manufacturing method thereof

[0001] The embodiments generally relate to a ceramic sealed component (hereinafter referred to as a ceramic sealed component) in which a ceramic component and a metal component are joined together, such as for use in electric power pipes.

[0002] As ceramic sealing parts for magnetrons, power tubes, and electron tubes, metallized layers mainly composed of high-melting point metals such as molybdenum (Mo) are coated with alumina (aluminum oxide: Al ２ O ３ Ceramic sealed components formed on ceramic components such as ceramics, ceramic alloys, and ceramic alloys are used. Ceramic sealed components bond ceramics to metals, blocking external air and hermetically sealing the interior of the component, thereby protecting the interior from the external environment and providing electrical insulation through the ceramics. The ceramic sealed component has a ring-shaped metallized layer primarily composed of molybdenum formed on two bottom surfaces (first and second bottom surfaces) that form the joining portion of a cylindrical ceramic component made of sintered alumina. A nickel (Ni) layer of a predetermined thickness is formed on the surface of this metallized layer to improve the bonding strength with a cylindrical metal component to be bonded to the ceramic sealed component and to perform sealing. This nickel layer and the cylindrical metal component are bonded using silver solder (e.g., BAg-8).

[0003] As a ceramics-sealed component, an electron tube having a vacuum airtight structure in which a metal surface made of molybdenum is formed at the joining portion of a cylindrical ceramic, and a cylindrical iron metal is joined via a brazing material has been disclosed (Patent Document 1). According to Patent Document 1, by replacing the metal component joined to the ceramic from Kovar with iron, it is possible to manufacture a low-cost electron tube.

[0004] Also, a vacuum switch outer tube has been disclosed in which a nickel-based alloy is bonded to ceramics using an active metal without using a high-melting-point metal such as molybdenum (Patent Document 2). According to Patent Document 2, a vacuum switch outer tube with high bonding strength can be manufactured without forming intermetallic compounds that cause instability in the bonded state. Also, a bonded body using nickel-free stainless steel has been disclosed (Patent Document 3). According to Patent Document 3, airtightness and bonding strength can be maintained because compounds between the active metal and nickel are not formed.

[0005] Japanese Patent Application No. 1-46978 Japanese Patent Application Laid-Open No. 2001-220253 International Publication No. 2023 / 063396

[0006] Metallizing the ceramic surface with a high-melting point metal such as molybdenum requires a furnace to heat the surface to a high temperature of 1400°C or higher, and the high-temperature treatment requires high energy costs. In addition, it is difficult to braze the formed high-melting point metallized layer to a metal part as is, and the surface must be plated with nickel or other metals, making the process complicated.

[0007] In contrast, joining using active metal brazing filler metal has the advantage of being heated at temperatures below 1000°C, which is beneficial in terms of energy costs. However, when nickel is plated on metal parts to improve rust resistance and wettability, the nickel and active metal form compounds that reduce the joining strength and cause leak defects.

[0008] The embodiments solve these problems and relate to a highly productive ceramic sealed component and a method for manufacturing the same, which suppresses poor joining and leaking when joining ceramic components and metal components with an active metal brazing material.

[0009] The ceramic sealed component of the embodiment is a ceramic sealed component in which a ceramic component and a nickel-plated metal component are joined by a joining layer containing silver, copper, an active metal, and a low-melting-point metal, and a compound of nickel and the active metal is formed in the joining layer, and the distance between the compound and the surface of the joining layer is 10 μm or more.

[0010] Fig. 1 is a perspective view showing an example of a ceramic seal component according to an embodiment; Fig. 2 is a longitudinal cross-sectional view showing an example of a ceramic seal component according to an embodiment; Fig. 3 is a view showing an example of a cross-section of a joint portion of a ceramic seal component according to an embodiment; Fig. 4 is a view showing an example of an enlarged view of a cross-section of a joint portion of a ceramic seal component according to an embodiment; Fig. 5 is a view showing an example of a mass % of a cross-section of a joint portion of a ceramic seal component according to an embodiment; Fig. 6 is a cross-sectional view showing an example of a manufacturing process of a ceramic seal component according to an embodiment; Fig. 7 is a view showing an example of a heating profile of a ceramic seal component according to an embodiment; Embodiment

[0011] The ceramic sealed component of the embodiment is a ceramic sealed component in which a ceramic component and a nickel-plated metal component are joined by a joining layer containing silver, copper, an active metal, and a low-melting-point metal, and a compound of nickel and the active metal is formed in the joining layer, and the distance between the compound and the surface of the joining layer is 10 μm or more.

[0012] FIG. 1 shows an example of a perspective view of a ceramic sealing component 1 according to an embodiment. Reference numeral 3 denotes a cylindrical ceramic component, and reference numeral 2 denotes a cylindrical metal component. The metal component 2 is joined at two ring-shaped bottom surfaces (first and second bottom surfaces) that form the joining portion of the ceramic component 3. FIG. 1 shows an example in which the metal component 2 is joined to the first bottom surface (e.g., upper end surface) and the second bottom surface (e.g., lower end surface) of the ceramic component 3. The embodiment is not limited to this form, and may include a form in which a metal component is joined to a rectangular cylindrical ceramic component, a form in which a metal component is not present on one bottom surface (e.g., lower bottom surface) but is joined only to the other bottom surface (e.g., upper bottom surface), or a form in which a metal component is joined to a ceramic component having openings in two or more locations on one bottom surface (e.g., upper bottom surface).

[0013] Figure 2 shows an example of a longitudinal cross-sectional view (a cross-section along a central axis perpendicular to the bottom surface) of a ceramic sealed component 1 according to the embodiment. The ceramic sealed component 1 according to the embodiment includes a cylindrical ceramic component 3 made of alumina, for example, and a metal component 2 bonded thereto. The metal component 2 is, for example, a nickel-plated metal component made of iron (Fe) or Kovar (Fe-Ni-Co). A bonding layer 4 (shown in Figure 3) is present between the ceramic component 3 and the metal component 2, maintaining a seal (airtightness) between the interior and exterior of the component.

[0014] The ceramic component 3 is preferably made of one of alumina, aluminum nitride, silicon nitride, and zirconia-doped alumina (alzir). Alumina includes alumina-based ceramics in which other ceramics are added to alumina. For example, zirconia-doped alumina is a sintered body made by mixing alumina and zirconium oxide. A sintering aid other than zirconia may also be added to the alumina. This is because the added sintering aid forms a grain boundary phase consisting of a glass phase, thereby densifying the alumina sintered body. Examples of sintering aids include compounds of manganese (Mn), silicon (Si), magnesium (Mg), calcium (Ca), etc., and it is preferable to add at least one of them in a total amount of 1% by mass to 15% by mass in terms of simple metal elements. Furthermore, the ceramic component 3 is preferably made of alumina, which offers good cost performance as an insulating and sealed component.

[0015] The material of the metal component 2 to be bonded to the ceramic component 3 is preferably iron (Fe) and iron alloys, iron-nickel alloys, copper (Cu) and copper alloys, tungsten (W), or molybdenum (Mo). Examples of iron alloys include carbon steels such as rolled steel, and alloy steels such as chromium steel and stainless steel. Examples of iron-nickel alloys include 42 alloy (42% Ni by mass, 0.8% or less Mn by mass, balance Fe) and Kovar (29% Ni by mass, 17% Co by mass, balance Fe). Iron and iron alloys offer excellent cost performance, while iron-nickel alloys offer excellent physical properties such as thermal expansion coefficients. Furthermore, copper and copper alloys are easily deformed to relieve stress due to differential thermal expansion. Therefore, when the impact of heat is significant, it is preferable to form metal components from copper and copper alloys. Examples of copper alloys include pure copper such as oxygen-free copper, tough pitch copper, and deoxidized copper, as well as high-copper alloys such as beryllium copper and titanium copper. For this reason, depending on the application, iron and iron alloys, iron-nickel alloys, copper and copper alloys are preferably used as the metal component 2. It is also possible to join two or more types of metal components 2 to the ceramic component 3, such as by using Kovar for one metal component 2 and copper for the other. The metal component 2 is manufactured by processing the metal component 2 into a predetermined shape using press working, cutting, bending, and other processes. After processing into the component shape, the metal component 2 is nickel-plated to improve corrosion resistance and wettability. Furthermore, when a metal component 2 made of copper and copper alloys and another nickel-plated metal component 2 are simultaneously joined to the ceramic component 3, the metal component 2 made of copper and copper alloys is easily wetted with brazing filler metal components even without nickel plating, so nickel plating is not necessary.

[0016] The thickness of the nickel plating applied to the metal part 2 is 0.5 μm or more and 3.0 μm or less. If the nickel plating thickness is less than 0.5 μm, the wetting with the brazing filler metal will be poor, and there is a possibility that areas that do not wet with the brazing filler metal (brazing filler cracks) will occur, which will cause a decrease in joint strength and leakage defects. If the nickel plating thickness exceeds 3.0 μm, further improvement in wettability will not be obtained. In addition, if the nickel plating is too thick, excess nickel will form a compound with the active metal.

[0017] 3 shows an example of a longitudinal cross section of a joint of a ceramic sealed component 1 according to an embodiment, which is an enlarged view of part A in FIG. Reference numeral 1 denotes a ceramic sealed component, 2 denotes a metal component, 3 denotes a ceramic component, and 4 denotes a joint layer. The joint layer 4 on the ceramic component 3 side is formed from a brazing metal such as copper (Cu) or silver (Ag), an active metal such as titanium (Ti), zirconium (Zr), or hafnium (Hf), and a low-melting-point metal such as indium (In), tin (Sn), bismuth (Bi), antimony (Sb), or zinc (Zn).

[0018] The bonding layer 4 is an active metal brazing layer made of an active metal brazing material, and includes brazing metals (silver and copper), an active metal, and a low-melting-point metal. The copper and silver used as the brazing metals of the bonding layer 4 have relatively low melting points and melt easily at temperatures suitable for brazing. Furthermore, alloying copper and silver further lowers the melting point. The melting point of the alloyed copper and silver is lower than that of the metal components 2 used in brazing, offering the advantage of being able to join the metal components 2 without melting them. Copper and silver also have excellent fluidity and permeability, which are necessary for brazing, and easily penetrate between the components via capillary action. Furthermore, copper and silver contribute to the strength and durability of the brazed joint. Copper and silver are less likely to generate stress between the ceramic component 3 and the metal component 2 when cooling after brazing, making the joint less susceptible to cracking and deformation. They also have excellent thermal and electrical conductivity, which does not significantly affect the functionality of the brazed joint.

[0019] The active metal of the bonding layer 4 reacts with ceramics that have poor wettability with metals, reducing interfacial energy and improving wettability. Improved wettability allows the brazing filler metal to penetrate more easily into gaps between the components, improving bonding strength. The active metal also forms metallic bonds between the atoms of the base metal and brazing filler metal, creating a solid solution at the bonding interface and contributing to the strength and durability of the bonded joint. The active metal readily reacts with nickel to form nickel-active metal compounds. Therefore, the active metal readily reacts with nickel contained in the metal component 2 or the nickel plating formed on the surface of the metal component 2 to form nickel-active metal compounds. These nickel-active metal compounds readily react with external atmospheres, such as hydrogen, and become embrittled, potentially resulting in reduced bonding strength and leak defects.

[0020] The low-melting-point metal in the bonding layer 4 has a lower melting point than the other elements contained in the bonding layer 4. The melting points of low-melting-point metals are indium (157°C), tin (232°C), bismuth (271°C), antimony (630°C), and zinc (419°C). These melting points are lower than the other metals contained in the bonding layer, such as silver (961°C), copper (1085°C), titanium (1666°C), zirconium (1852°C), and hafnium (2233°C). For this reason, low-melting-point metals diffuse faster than other metals when heated. By diffusing faster than nickel and active metals, the added low-melting-point metal reacts with copper or silver to form a bonding layer, preventing nickel-active metal compounds from precipitating on the surface of the bonding layer. Low-melting-point metals are also added to active metal brazing pastes. This is because adding low-melting-point metals to brazing pastes made of silver and copper lowers the melting point of the silver-copper alloy, causing it to melt and solidify first.

[0021] The ratio of the low-melting point metal is 5% by mass or more and 15% by mass or less. If the amount of the low-melting point metal is less than 5% by mass, diffusion into the brazing material layer is insufficient, and the effect of preventing the nickel-active metal compound from precipitating on the outermost surface of the bonding layer cannot be obtained. Conversely, if the ratio of the low-melting point metal is more than 15% by mass, the ratio of silver and copper, which are the main components of the brazing material, decreases, and the mechanical properties and other functions of the bonding layer may be reduced.

[0022] FIG. 4 shows an example of a longitudinal cross section of a joint portion of a ceramic sealed component 1 according to an embodiment, which is an enlarged view of portion B in FIG. 3 . Reference numeral 5 denotes an active metal layer, primarily composed of an active metal, within the joint layer 4. The active metal layer 5 exists on the surface of the ceramic component 3 and contributes to the joint between the ceramic component 3 and the metal component 2. Reference numeral 6 denotes a brazing layer (hereinafter referred to as the "brazing layer") within the joint layer 4, composed of brazing metals (silver and copper) and a low-melting-point metal. The brazing layer 6 exists between the active metal layer 5 and the metal component 2 near the end face of the metal component 2 and contributes to the joint between the active metal layer 5 and the metal component 2. The brazing layer 6 also forms a meniscus at a location on the side of the metal component 2 to improve the joint strength. Therefore, the brazing layer 6 forming the meniscus forms the outermost surface 61 (hereinafter referred to as the "brazing layer outermost surface") that is in contact with the external atmosphere. The brazing layer outermost surface 61 is composed of the brazing metals (silver and copper) and the low-melting-point metal. This is because, as in the manufacturing method described below, the low-melting-point metal contained in the active metal brazing paste printed on the ceramic component 3 diffuses to the outermost surface 61 of the brazing layer through heat treatment. Reference numeral 7 denotes nickel-active metal compounds (three are illustrated in FIG. 4 ) in the bonding layer 4. As in the manufacturing method described below, the active metal contained in the active metal brazing paste printed on the ceramic component 3 reacts with the nickel plating layer formed on the surface of the metal component 2 to form a nickel-active metal compound (hereinafter referred to as the "nickel-active metal compound") primarily composed of nickel and the active metal. The nickel-active metal compound 7 contains 50% or more by mass of nickel and the active metal. The nickel-active metal compound 7 may also contain brazing metals (silver and copper), low-melting-point metals, etc. As described above, the added low-melting-point metal diffuses quickly and reaches the outermost surface 61 of the brazing layer first, so the nickel-active metal compound 7 exists deeper than the outermost surface 61 of the brazing layer.

[0023] The distance L between the outermost surface 61 of the brazing material layer and the nickel-active metal compound 7 is 10 μm or more. If the distance L is less than 10 μm, the nickel-active metal compound 7 may react with the external atmosphere, such as oxygen or hydrogen, to become embrittled, possibly resulting in a decrease in airtightness and bonding strength.

[0024] The distance L between the outermost surface 61 of the brazing material layer and the nickel-active metal compound 7 is measured by observing the cross section of the joint. A simple method is to determine the distance from the distribution of elements. A cross section of the joint, such as that shown in FIG. 4, is color-mapped for nickel and the active metal using an energy dispersive X-ray fluorescence analyzer (EDX). The overlapping portion of the nickel and the active metal can be considered as the nickel-active metal compound 7, so the distance L between the outermost surface 61 of the brazing material layer and the nickel-active metal compound 7 can be measured.

[0025] If the boundary between the nickel and active metal compounds 7 is unclear, X-ray mass analysis can be performed across the boundary. Figure 5(a) is a schematic diagram showing the mass percentages of the constituent elements when measuring the distance L from direction D1 for part C in Figure 4. The mass percentages are measured for the constituent elements using an energy dispersive X-ray fluorescence analyzer (EDX). The distribution of the mass percentages of the brazing metals (silver and copper), active metals, low-melting-point metals, and nickel constituting the brazing layer 6 is shown from the outside (the portion of the ceramic metal circuit component exposed to the atmosphere, such as air or gas) to the inside (the interior of the bonding layer). The minimum mass percentage (zero) indicates a location where no observed element is present, and the mass percentage increases as the observed element is present. The location where any metal element exceeds 2 mass% is defined as the outermost position L1. Figure 5(b) is an enlarged view of part D in Figure 5(a). Position L2, which is the boundary between the brazing layer 6 and the nickel-active metal compounds 7, is defined as the location where nickel is 20 mass% or more. Therefore, the distance L is the distance between the position L1 and the position L2.

[0026] Figure 6 shows a process diagram of a method for manufacturing a ceramic seal component according to an embodiment. Figure 6(a) is a longitudinal cross-sectional view of a ceramic component 3. In Figure 6(a), chamfers are formed on the outer and inner peripheries of the ceramic component 3. It is possible to obtain a ceramic seal component 1 without forming chamfers, but ceramics are prone to chipping due to external impacts, and chamfering is effective in preventing chipping.

[0027] Figure 6(b) shows the state of an active metal brazing paste-printed part after the active metal brazing paste 8 has been printed and dried on the ceramic part 3. The surface of the active metal brazing paste 8 is approximately flat before joining because the paste is printed on the flat end surface of the ceramic part 3. Also, in Figure 6(b), the active metal brazing paste 8 is printed only on the flat portion of the end, but it is also possible to print the active metal brazing paste 8 on the chamfered portion as well.

[0028] The active metal brazing paste 8 is prepared by adding an organic binder and an organic solvent to a metal powder mixture containing one or more brazing metals (copper and silver), one or more active metals selected from titanium, zirconium, and hafnium, and one or more low-melting-point metals selected from indium, tin, bismuth, antimony, and zinc. The organic binder is not particularly limited as long as it is burned away during the drying and joining processes. A preferred example of the organic binder is ethyl cellulose. The organic solvent is not particularly limited as long as it is burned away during the drying and joining processes. Preferred examples of the organic solvent include terpineol and butyl carbitol. The active metal brazing paste 8 is prepared by mixing the active metal powder and brazing metal powder, and then mixing the mixture with the organic binder and organic solvent. The active metal content of the active metal brazing components is 0.1% by mass to 15% by mass, preferably 0.5% by mass to 10% by mass.

[0029] The printing thickness of the active metal brazing paste 8 is preferably 10 μm or more and 30 μm or less. If the printing thickness is less than 10 μm, the thickness of the active metal brazing layer will vary, reducing the bonding strength. On the other hand, if it exceeds 30 μm, no further effect will be obtained. The paste is printed to a uniform thickness on the end surface of the ceramic component using a method such as screen printing. If the printing thickness is uneven, the active metal brazing material will be excessive in thicker areas, causing brazing material pools and cracks due to thermal stress. Furthermore, in thinner areas, brazing material will run out, resulting in leakage defects. For this reason, it is preferable that the difference in printing thickness between thick and thin areas be 5 μm or less.

[0030] Figure 6(c) shows the state of a brazing paste-printed part obtained by printing and drying brazing paste 9 on the surface of the dried active metal brazing paste 8 in Figure 6(b). The brazing paste 9 is composed of a metal component 2 and a metal with good wettability with the active metal brazing material. Silver brazing filler metal is commonly used to join ceramic components 3 and metal components 2. Silver brazing filler metal is primarily composed of silver and copper, but may also contain other metal components such as zinc and nickel. Silver brazing filler metal (BAg-8), which is 72% silver and 28% copper, is commonly used to join ceramic components 3 and metal components 2. According to "Silver Brazing Filler Metal (JIS Z3261:1998)," BAg-8 contains 71% to 73% silver (Ag), 27% to 29% copper (Cu), and a total of 0.15% or less of other elements. Brazing filler metal paste 9 is a mixture of brazing metal powder, an organic binder, and an organic solvent. The organic binder is not particularly limited as long as it is burned away during the drying and joining processes. A preferred example of the organic binder is ethyl cellulose. The organic solvent is not particularly limited as long as it is burned away during the drying and joining processes. Preferred examples of the organic solvent are terpineol and butyl carbitol. The brazing paste is prepared, for example, by crushing and mixing metal powder, and then mixing it with an organic binder and an organic solvent.

[0031] The printing thickness of the brazing paste 9 is preferably 70 μm or more and 300 μm or less. If the printing thickness is less than 70 μm, the thickness of the brazing paste layer will vary, reducing the bonding strength. On the other hand, if it exceeds 300 μm, no further effect will be obtained. The paste is printed to a uniform thickness on the end surface of the ceramic component using a method such as screen printing. If the printing thickness is uneven, the active metal brazing paste will be excessive in the thicker parts, causing brazing paste pools and cracks due to thermal stress. Furthermore, in the thinner parts, brazing paste will run out, resulting in leakage defects. For this reason, it is preferable that the difference in printing thickness between the thicker and thinner parts be 20 μm or less.

[0032] Because the active metal brazing paste 8 contains an active metal, which reacts with nickel to form a compound that easily embrittles the active metal brazing material, it is preferable for the brazing paste 9 to cover the entire surface of the active metal brazing material after joining. When printing the same print pattern as the active metal brazing paste 8, the viscosity of the brazing paste 9 can be made lower than that of the active metal brazing paste 8 to spread and cover the entire surface during printing. Alternatively, the print pattern of the brazing paste 9 can be made larger (wider) than that of the active metal brazing paste 8 to cover the entire active metal brazing material layer. If the print pattern is too large, the brazing paste 9 will not react with the ceramic component 3 during heat treatment and will instead collect on the active metal brazing material layer or the metal component 2. If the brazing paste 9 is present in clumps around the active metal brazing material layer or the metal component, this can cause stress concentration. Therefore, when enlarging the print pattern of the brazing paste 9, it is preferable to enlarge it by no more than 0.1 mm compared to the print pattern of the active metal brazing paste 8.

[0033] 6(d) shows a state in which a metal part 2 is placed on the surface of the brazing paste 9 printed and dried on the brazing paste-printed part. When joining multiple metal parts 2 as shown in FIG. 2, multiple metal parts 2 are placed at the same time. In this state, the metal parts 2 are joined by performing a heat treatment.

[0034] The heat treatment profile is preferably performed in two stages: a primary heating temperature and a secondary heating temperature higher than the primary heating temperature. Figure 7 shows an example of a heat treatment profile, with the vertical axis representing temperature and the horizontal axis representing time. The primary heating temperature T1 is set to a temperature higher than the melting point of the low-melting-point metal because it is necessary to melt the low-melting-point metal. Furthermore, the time required to maintain the primary heating temperature T1 is preferably 10 to 30 minutes, so that the low-melting-point metal diffuses throughout the bonding layer. If the time is shorter than 10 minutes, the low-melting-point metal will not diffuse throughout, and the effect of preventing the nickel-active metal compound from precipitating on the outermost surface of the bonding layer will be lost. Furthermore, extending the time beyond 30 minutes will not achieve any further effect.

[0035] Furthermore, the difference between the primary heating temperature T1 and the secondary heating temperature T2 (T2 - T1) is 120°C or less. The secondary heating temperature T2 is performed while the low-melting-point metal is diffused due to the primary heating temperature T1, so the melting temperature of the brazing paste is lower than usual. Therefore, if the difference between the primary heating temperature T1 and the secondary heating temperature T2 (T2 - T1) is greater than 120°C and the secondary heating temperature T2 is high, the brazing paste spreads over the surface of the metal component 2, preventing the formation of a meniscus. The lack of a meniscus can result in a decrease in the bonding strength of the metal component 2. Furthermore, the holding time at the secondary heating temperature T2 is 1 to 10 minutes to melt the brazing filler metal. If the holding time is shorter than 1 minute, sufficient heating to melt the brazing filler metal is not achieved. Furthermore, extending the holding time beyond 10 minutes does not provide any additional benefits.

[0036] 6(e) shows the state after joining the metal part 2. The joining layer 4 creeps up onto the side surface of the metal part 2, forming a strong joint. In this way, the joining layer 4 covers the side surface of the metal part 2, resulting in high joining strength and leak-free sealing inside and outside the part.

[0037] Next, a method for manufacturing the ceramic sealing component 1 according to the embodiment will be described. The method for manufacturing the ceramic sealing component 1 is not particularly limited as long as the ceramic sealing component 1 has the above-described configuration, but the following methods can be mentioned as methods for obtaining the ceramic sealing component with a high yield.

[0038] An example of the ceramic part 3 according to the embodiment has a cylindrical shape, for example, an outer diameter of 50 mm, an inner diameter of 38 mm, and a height of 50 mm. The ceramic part 3 is susceptible to chipping and cracking at its corners due to external impacts. For this reason, it is preferable to chamfer the outer and inner peripheries of the end faces. Examples of the chamfer shape include C-chamfering and R-chamfering, and the chamfer size is preferably 0.1 mm or more and 2 mm or less.

[0039] Examples of materials for the metal component 2 according to the embodiment include iron and iron alloys, copper and copper alloys, iron-nickel alloys, tungsten, and molybdenum. One example of the shape of the metal component 2 according to the embodiment is a substantially cylindrical shape. For example, in the example shown in FIG. 2, the metal component 2 has a height of 20 mm, an outer diameter of 46 mm, and an inner diameter of 44 mm. These metal components 2 are nickel-plated to a thickness of 0.5 μm to 3.0 μm to improve corrosion resistance and wettability.

[0040] Active metal brazing filler metals and brazing filler metals are in the form of paste. Sheets and wires require a process in which the active metal brazing filler metal is melted and processed into a sheet or wire shape, and then cut to the specified dimensions to match the product shape. In contrast, pastes, although they require a paste manufacturing process, are easy to handle; for example, they can be printed in the required locations to match the product shape. In addition, if the amount of active metal brazing filler metal is too small, unbonded areas will occur, resulting in braze breaks, and if too much, braze pools will occur, causing stress fractures. Therefore, the amount of paste used can be adjusted to match the bonding area.

[0041] The active metal brazing paste 8 is prepared by adding an organic binder and an organic solvent to a mixture of active metal powder and brazing metal powder. The organic binder is not particularly limited as long as it is burned away during the drying and joining processes. A preferred example of the organic binder is ethyl cellulose. The organic solvent is not particularly limited as long as it is burned away during the drying and joining processes. Preferred examples of the organic solvent include terpineol and butyl carbitol. The active metal brazing paste is prepared, for example, by crushing and mixing the active metal powder and brazing metal powder, and then mixing them with the organic binder and organic solvent. The active metal brazing paste contains an active metal in an amount of 0.1% by mass to 15% by mass, preferably 0.5% by mass to 10% by mass.

[0042] The printing thickness of the active metal brazing paste 8 is preferably 10 μm or more and 30 μm or less. If the printing thickness is less than 10 μm, the thickness of the active metal brazing layer will vary, reducing the bonding strength. On the other hand, if it exceeds 30 μm, no further effect will be obtained. The paste is printed to a uniform thickness on the end surface of the ceramic component 3 using a screen printing method or the like. If the printing thickness is uneven, the active metal brazing material will be excessive in thicker areas, causing brazing material pools and cracks due to thermal stress. Furthermore, in thinner areas, leakage defects will occur due to the active metal brazing material running out. For this reason, it is preferable that the difference in printing thickness between thick and thin areas be 5 μm or less.

[0043] The paste printed on the ceramic part 3 is dried in the atmosphere or the like. If the drying temperature is low and the drying time is short, the solution components of the paste are not sufficiently volatilized, and the remaining solution may volatilize during bonding, resulting in the formation of voids. Conversely, if the drying temperature is high and the drying time is long, oxidation of the paste surface may progress, causing changes in the bonding temperature. For this reason, the drying temperature is set to 50°C or higher and 100°C or lower, preferably 60°C or higher and 80°C or lower. The drying time is set to 5 to 30 minutes, preferably 10 to 20 minutes.

[0044] The brazing paste 9 is composed of a metal component 2 and an active metal brazing material, and a metal with good wettability. A brazing material commonly used to join a ceramic component 3 and a metal component 2 is silver brazing. Silver brazing is primarily composed of silver and copper, but may also contain other metal components such as zinc and nickel. A commonly used silver brazing material (BAg-8) is a 72% silver-28% copper brazing material. According to "Silver Brazing (JIS Z3261:1998)," BAg-8 contains 71% to 73% silver (Ag), 27% to 29% copper (Cu), and a total of 0.15% or less of other elements. The brazing paste 9 is a mixture of brazing metal powder, to which an organic binder and organic solvent are added. The organic binder is not particularly limited as long as it is burned away during the drying and joining processes. One preferred example of an organic binder is ethyl cellulose. The organic solvent is not particularly limited as long as it is burned off during the drying and joining processes. Preferred examples of the organic solvent include terpineol and butyl carbitol. The brazing paste is prepared, for example, by crushing and mixing metal powder, and then mixing it with an organic binder and an organic solvent.

[0045] The printing thickness of the brazing paste 9 is preferably 70 μm or more and 300 μm or less. If the printing thickness is less than 70 μm, the thickness of the brazing paste layer will vary, reducing the joint strength. On the other hand, if it exceeds 300 μm, no further effect will be obtained. The paste is printed to a uniform thickness on the end surface of the ceramic component 3 using a screen printing method or the like. If the printing thickness is uneven, the brazing paste will be excessive in thicker areas, causing brazing paste pools and cracks due to thermal stress. Furthermore, in thinner areas, leakage defects will occur due to lack of active metal brazing paste. For this reason, it is preferable that the difference in printing thickness between thick and thin areas be 20 μm or less, and even 15 μm or less.

[0046] The brazing paste 9 printed on the active metal brazing layer made of the active metal brazing paste 8 is dried in the atmosphere or the like. If the drying temperature is low and the drying time is short, the solution components of the paste are not sufficiently volatilized, and the remaining solution may volatilize during bonding, resulting in the formation of voids. Conversely, if the drying temperature is high and the drying time is long, oxidation of the paste surface may progress, potentially changing the bonding temperature conditions. For this reason, the drying temperature is 50°C or higher and 100°C or lower, preferably 60°C or higher and 80°C or lower. The drying time is 5 to 30 minutes, preferably 10 to 20 minutes.

[0047] After the brazing paste 9 dries, the metal part 2 is placed on the dried paste surface and heated to form a bond. The heat treatment profile preferably includes a two-stage heating period: a primary heating and a secondary heating at a higher temperature. The primary heating temperature T1 is 650°C or higher and 850°C or lower, preferably 700°C or higher and 800°C or lower. The bonding time for the primary heating is preferably 10 to 30 minutes after the primary heating temperature is reached. At the secondary heating temperature T2 following the primary heating, the difference (T2 - T1) between the primary heating temperature T1 and the secondary heating temperature T2 is preferably 120°C or lower. The bonding time for the secondary heating is preferably 1 to 10 minutes after the secondary heating temperature T2 is reached. As shown in Figure 6(e), the bonding layer 4 melts and spreads over the surface of the metal part 2, resulting in a sealed bond. If the bonding temperature is low and the bonding time is short, the active metal brazing material may not melt sufficiently and bonding may not occur. Conversely, if the joining temperature is high and the joining time is long, the brazing material may melt too much and spread, causing brazing material to break down or voids to form.

[0048] Furthermore, the bonding atmosphere may be a non-oxidizing atmosphere as required. Examples of non-oxidizing atmospheres include a nitrogen atmosphere and a hydrogen nitrogen atmosphere. By using a non-oxidizing atmosphere, oxidation of the bonding layer 4 can be suppressed, thereby improving the bonding strength. A continuous furnace or a batch furnace is used for the bonding process. A continuous furnace is superior in terms of mass production, while a batch furnace allows for easy control of the temperature and atmosphere. Bonding is performed by heat-treating the parts in the above atmosphere for a predetermined period of time.

[0049] The thickness of the bonding layer 4 bonding the ceramic component 3 and the metal component 2 is preferably 80 μm or more. This is because, as described above, the bonding layer 4 is formed from an active metal brazing paste 8 of 10 μm or more and a brazing paste 9 of 70 μm or more. The thickness of the bonding layer 4 in this case refers to the distance between the bonding surface of the metal component 2 and the ceramic component 3. For example, in FIG. 6( e ), the tip (end face) of the metal component 2 is flat. In this case, the thickness of the bonding layer 4 refers to the distance between the flat portion at approximately the center of the metal component 2 and the flat portion of the ceramic component 3. Furthermore, if the tip of the metal component 2 is bent into a flange shape and bonded to the ceramic component 3, the thickness of the bonding layer 4 is defined as the thickness of the approximately central portion of the bent flange. Furthermore, if the tip of the metal component 2 is pointed, such as U-shaped or V-shaped, the thickness of the bonding layer 4 is defined as the distance between the pointed tip and the ceramic surface.

[0050] As described above, according to the method for manufacturing the ceramic seal component 1 in the embodiment of the present invention, it is possible to obtain a ceramic seal component that is excellent in cost performance while maintaining the airtightness performance of the seal component.

[0051] (Examples 1 to 6, Comparative Examples 1 to 6) Alumina and manganese oxide (MnO ２ ), silicon dioxide (silica: SiO ２ A granulated powder having a composition of 92 mass% alumina was prepared by adding an auxiliary agent of yttria (yttrium oxide: Y), magnesium oxide (magnesia: MgO). The granulated powder was molded using a die press and sintered in air at 1500°C to obtain a cylindrical ceramic part having an outer diameter of 50 mm, an inner diameter of 40 mm, a height of 50 mm, an outer diameter C-chamfer of 0.5 mm, and an inner diameter C-chamfer of 0.5 mm. Also, a granulated powder having a composition of 92 mass% alumina was prepared by adding an auxiliary agent of yttria (yttrium oxide: Y), magnesium oxide (magnesia: MgO) to aluminum nitride (AlN). ２ O ３ The granulated powder was molded using a die press and sintered at 1800°C in nitrogen to obtain a cylindrical ceramic part having the same dimensions as the alumina part.

[0052] The metal parts were obtained by pressing iron, stainless steel (SUS304), and Kovar into cylindrical shapes with an outer diameter of 46 mm, an inner diameter of 44 mm, and a height of 20 mm, as shown in Table 1. The surfaces of the processed metal parts were plated with nickel to the thickness shown in Table 1.

[0053] Next, silver powder, copper powder, low-melting-point metal powder, and active metal powder were mixed in the mass percentages shown in Figure 1. In Example 1, the mixture consisted of 30 mass% copper powder, 10 mass% indium powder, 2 mass% titanium, and residual silver powder. In Table 1, Example 1 is represented as "Ag-30Cu-10In-2Ti," and this is also true for other examples and comparative examples. The mixed metal powder was mixed with ethyl cellulose and terpineol and kneaded to form a paste to prepare an active metal brazing paste. A 30 μm-thick active metal paste was printed on the upper and lower ends (ring portions) of a ceramic part by screen printing using a 100-mesh screen with an outer diameter of 48 mm and an inner diameter of 42 mm, and then dried at 100°C in air. The active metal brazing paste was then dried.

[0054] Next, silver powder and copper powder were mixed so that the metal powder compounding ratio was 72:28 by mass%, and paste was made in the same manner as for the active metal brazing paste to prepare a silver brazing paste. A brazing paste having a thickness of 100 μm was printed by screen printing using a 100 mesh screen with an outer diameter of 48 mm and an inner diameter of 42 mm on the upper and lower ends (ring portions) of the ceramic part on which the active metal brazing layer was formed, and dried at 100° C. in air. Next, the metal part, ceramic part, and metal part were set in a jig in this order, and then heated in a vacuum furnace (1×10 －２ The metal part and the ceramic part were joined by heating at a pressure of 1000 kJ / cm 2 (or less) at a primary heating temperature T1 shown in Table 2 for 20 minutes and at a secondary heating temperature T2 for 5 minutes to produce a ceramic sealed part.

[0055]

[0056] As can be seen from Tables 1 and 2, the nickel plating thickness, active metal brazing paste ratio, and heating temperature difference (T2-T1) values ​​in the Examples were within the preferred ranges, while the Comparative Examples were outside the preferred ranges.

[0057] Next, the ceramic sealed component was cut at the center as shown in Figure 2, and the joint area was polished as shown in Figure 3. Next, area analysis of the constituent elements was performed on the area around the joint using an energy dispersive X-ray fluorescence analyzer (EDX). From the state of the area analysis, the position D1 in Figure 4 was determined, and a mass % analysis was performed. The joint distance L, as shown in Figure 5, was calculated from the mass % analysis value. The results are shown in Table 3.

[0058] Next, a hydrogen heating test was conducted to check for embrittlement from the external atmosphere. In the hydrogen heating test, the ceramic sealed parts were heated five times in a 20% hydrogen nitrogen atmosphere at 400°C or higher for 10 minutes in a belt heating furnace. After the heat treatment, the joints were visually observed, and those without any change in surface color (discoloration) were rated as pass (O), and those with discoloration (including partial discoloration such as spots) were rated as fail (X).

[0059] Next, the two metal parts above and below the ceramic sealed part after the hydrogen heat treatment were pulled up and down using an Instron tensile tester to determine the bonding strength.

[0060] In addition, a helium leak test was performed by applying silicone to the upper part of the ceramic sealed part after the hydrogen heat treatment with a circular jig made of Viton rubber and holding it down, and then fixing the lower part to a helium leak detector and sucking it in. The helium leak test was performed in accordance with the vacuum spray method (spray method) of the "Helium Leak Test Method" (JIS Z2331:2006), and the leak rate was 1 × 10 at a vacuum of 1.3 μPa. －９ P.A.M. ３ If no leakage of 1 / s or more occurred, it was judged as pass (O), and if leakage occurred, it was judged as fail (X).

[0061]

[0062] As can be seen from Table 3, the bonding distance L in the examples was 10 μm or more, which was within the preferred range. This is because the bonding conditions in the examples prevented the nickel-active metal compound from precipitating on the bonding layer surface due to the diffusion of the low-melting point metal. On the other hand, some of the comparative examples were outside the preferred range. This was because a barrier to prevent the nickel-active metal compound from precipitating was not formed.

[0063] Furthermore, as can be seen from Table 3, in the hydrogen heating test, no discoloration was observed in the Examples. This is because a sufficient bonding distance L was obtained, so embrittlement due to hydrogen did not occur. On the other hand, discoloration was observed in the Comparative Examples. This is because a sufficient bonding distance L was not obtained, so embrittlement due to hydrogen occurred.

[0064] Furthermore, as can be seen from Table 3, the bonding strength of the examples was a good value of 40 MPa or more. This is because the bonding conditions of the examples formed a strong bonding layer that did not become embrittled in the hydrogen heating test. In contrast, the bonding strength of the comparative examples was 25 MPa or less. This is because embrittlement progressed during the hydrogen heating test, leading to a decrease in bonding strength.

[0065] Furthermore, the ceramic sealed components according to the examples did not experience any leak defects in the helium leak test. This is because they were not embrittled in the hydrogen heating test either. In contrast, leak defects occurred in the comparative examples. This is because embrittlement progressed in the hydrogen heating test, reducing the bonding strength and making it impossible to maintain airtightness.

[0066] As is clear from the results shown above, the Examples showed improved resistance to the external atmosphere compared to the Comparative Examples.

[0067] Although several embodiments of the present invention have been described above, these embodiments are presented by way of example only and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, modifications, etc. can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as set forth in the claims. Furthermore, the above-described embodiments can be implemented in combination with each other.

Claims

1. A ceramic sealed component in which a ceramic part and a nickel-plated metal part are joined by a joining layer containing silver, copper, an active metal, and a low-melting point metal, wherein a compound of nickel and the active metal is formed in the joining layer, and the distance between the compound and the outermost surface of the brazing material layer in contact with the external atmosphere is 10 μm or more.

2. The ceramic sealed part according to claim 1, characterized in that the active metal is one or more metals selected from titanium, zirconium and hafnium, and the low melting point metal is one or more metals selected from indium, tin, bismuth, antimony and zinc.

3. A ceramic sealed part according to claim 1 or 2, characterized in that the metal part is one or more metal parts selected from the group consisting of iron, iron alloys, iron-nickel alloys, copper and copper alloys.

4. A ceramic sealed part according to claim 1 or 2, characterized in that the thickness of the nickel plating is 0.5 μm or more.

5. A ceramic sealed part according to claim 1 or 2, characterized in that the ceramic part is made of alumina, aluminum nitride, silicon nitride or alumina with added zirconia.

6. A method for manufacturing a ceramic sealed part for joining a ceramic part and a nickel-plated metal part, comprising the steps of: printing and drying an active metal paste containing at least copper, an active metal, and a low-melting point metal on the ceramic part to obtain an active metal paste-printed part; printing and drying a brazing material paste containing at least silver and copper so as to cover the entire surface of the active metal paste-printed part to obtain a brazing material paste-printed part; and placing the metal part on the brazing material paste-printed part and performing a bonding process in which the difference (T2-T1) between a primary heating temperature T1 and a secondary heating temperature T2 which is higher than the primary heating temperature is 120°C or less.

7. A method for manufacturing a ceramic sealed part as described in claim 6, characterized in that the printing thickness of the active metal paste is 30 μm or less and the difference in printing thickness is 5 μm or less, and the thickness of the brazing paste is 70 μm or more and the difference in printing thickness is 20 μm or less.

8. A method for manufacturing a ceramic sealed part according to claim 6 or 7, characterized in that the time for which the primary heating temperature is kept is from 10 minutes to 30 minutes, and the time for which the secondary heating temperature is kept is from 1 minute to 10 minutes.

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