Ceramic sealing component and method for manufacturing the same

Abstract

To provide a ceramic sealing component which is excellent in airtight characteristics, and a method for manufacturing the same.SOLUTION: A ceramic sealing component is formed by joining a ceramic component and a nickel-plated metal component by a joint layer containing silver, copper, active metal and low melting point metal, wherein the joint layer is formed of a compound of the nickel and the active metal, and a distance between the compound and the surface of the joint layer is 10 μm or more. A method for manufacturing a ceramic sealing component joining the ceramic component and the metal component includes: a step of printing drying an active metal paste containing at least copper, active metal and low melting point metal in the ceramic component, and obtaining an active metal paste printing component; a step of printing drying a solder material paste containing at least silver and copper, on the surface of the active metal paste printing component, and obtaining a solder material paste printing component; and a joint step of installing the metal component in the solder material paste printing component, and heating the solder material paste printing component.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] 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 used in a power tube or the like are joined together.

Background Art

[0002] As a ceramic-sealed component for a magnetron, a power tube, or an electron tube, a ceramic-sealed component in which a metallized layer mainly composed of a high melting point metal such as molybdenum (Mo) is formed on a ceramic component such as alumina (aluminum oxide: Al2O3) is used. The ceramic-sealed component can protect the inside from the external environment and provide electrical insulation with the ceramic by joining the ceramic and the metal to block the outside air and hermetically seal the inside of the component. For example, in a ceramic-sealed component having a shape as shown in FIG. 1, a metallized layer mainly composed of molybdenum is formed on the ring portions of the upper and lower end surfaces of a cylindrical ceramic component made of an alumina sintered body. On the surface of this metallized layer, a nickel (Ni) layer with a predetermined thickness is formed to improve the bonding strength with other metal components and perform sealing. The nickel portion and the cylindrical metal component are joined by silver brazing (for example, BAg-8).

[0003] An electron tube having a vacuum hermetic sealing structure in which a metal surface made of molybdenum is formed on a ceramic cylinder and an iron metal cylinder is joined with a brazing material is disclosed as a ceramic-sealed component (Patent Document 1). According to Patent Document 1, a low-cost electron tube can be manufactured by replacing the metal cylinder from kovar to iron.

[0004] Also, a vacuum switch outer tube has been disclosed in which a nickel-based alloy is bonded to ceramics by 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 an unstable bonded state. Also, a bonded body using stainless steel that does not contain nickel has been disclosed (Patent Document 3). According to Patent Document 3, airtightness and bonding strength can be maintained because no compound is formed between the active metal and nickel. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Application No. 1-46978 [Patent Document 2] JP 2001-220253 A [Patent Document 3] International Publication No. 2023 / 063396 Summary of the Invention [Problem to be solved by the invention]

[0006] When metallizing the ceramic surface with a high-melting point metal such as molybdenum, a furnace is required to heat the surface to a high temperature of over 1400°C, and the energy costs are high because the treatment is carried out at such high temperatures. In addition, it is difficult to braze the formed high-melting point metal metallization layer to metal parts as is, and the surface must be plated with nickel or other metals, making the process complicated.

[0007] In contrast, active metal brazing material bonding has the advantage in terms of energy costs, since the heating temperature is 1000°C or less. However, when nickel plating is applied to metal parts to improve rust resistance and wettability, the nickel and active metal form compounds that reduce the bonding strength and cause leak defects.

[0008] The embodiment solves such problems and relates to a highly productive ceramic sealed component that suppresses joint failure and leak failure when a ceramic component and a metal component are joined with an active metal brazing material, and a method for manufacturing the same.

Means for Solving the Problems

[0009] The ceramic sealed component according to 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. A compound of nickel and an 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.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Mode for Carrying Out the Invention

[0011] The ceramic sealed component according to 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. A compound of nickel and an 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 sealed component 1 according to the embodiment. 3 is a cylindrical ceramic component, and 2 is a cylindrical metal component. FIG. 1 shows an example in which the metal component 2 is joined to the upper end face and the lower (opposite side) end face of the ceramic component 3. The embodiment is not limited to such a form, and a rectangular prism-shaped ceramic component or metal component may be used. The form in which the lower bottom surface is a ceramic component and is joined only to the metal component on the upper side (one side), or the form in which a metal component is joined to a ceramic component having two or more openings on one surface may also be used.

[0013] FIG. 2 shows an example of a cross-sectional view of a ceramic sealed component according to the embodiment. In the ceramic sealed component 1 according to the embodiment, for example, the ceramic component 3 is a ceramic component made of cylindrical alumina. Further, for example, the metal component 2 is a metal component obtained by nickel-plating iron (Fe) or kovar (Fe-Ni-Co). There is a joining layer between the ceramic component 3 and the metal component 2, which maintains the sealing property (airtightness) between the inside and the outside of the component.

[0014] The ceramic component 3 is preferably any one of alumina, aluminum nitride, silicon nitride, and alumina added with zirconia (aluzir). Alumina includes alumina-based ceramics obtained by adding other ceramics or the like to alumina. For example, alumina added with zirconia is a sintered body obtained by mixing alumina and zirconium oxide. Further, a sintering aid other than zirconia may be added to alumina. This is because the added sintering aid forms a grain boundary phase composed of a glass phase to densify the alumina sintered body. Examples of the sintering aid include compounds such as manganese (Mn), silicon (Si), magnesium (Mg), and calcium (Ca), and it is preferable to add at least one or more of them in a total amount of 1 to 15% by mass in terms of the elemental metal. Further, the ceramic component is preferably alumina, which has good cost performance as an insulating sealing component.

[0015] The material of the metal part 2 joined to the ceramic part 3 is preferably iron (Fe) and iron alloys, iron-nickel alloys, copper (Cu) and copper alloys, tungsten (W), and molybdenum (Mo). 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 (Ni 42% by mass, Mn 0.8% by mass or less, balance Fe), Kovar (Ni 29% by mass, Co 17% by mass, balance Fe), etc. Iron and iron alloys are excellent in cost performance, and iron-nickel alloys are excellent in physical properties such as the coefficient of thermal expansion. Also, copper and copper alloys are easily deformed to relieve stress due to the difference in thermal expansion, and when the influence of heat is large, it is preferable to form the metal part with copper and copper alloys. Copper alloys include pure copper such as oxygen-free copper, tough pitch copper, and deoxidized copper, and high copper alloys such as beryllium copper and titanium copper. Therefore, depending on the application, it is preferable to use metal parts made of iron and iron alloys, iron-nickel alloys, copper and copper alloys. Also, it is possible to use two or more types of metal parts such as Kovar on one side and copper on the opposite side for the metal part. Further, the metal part is manufactured by processing it into a predetermined shape by press working, cutting, bending, etc. The metal part is nickel-plated after being processed into the part shape to improve corrosion resistance and wettability. Also, when simultaneously joining a metal part made of copper and copper alloys and another metal part that has been nickel-plated, the metal part made of copper and copper alloys can be joined without nickel-plating because it is easily wetted by the brazing material component.

[0016] The thickness of the nickel plating is 0.5 to 3.0 μm. If the thickness of the nickel plating is less than 0.5 μm, the wettability with the brazing material deteriorates, and there is a possibility that non-wetted areas (brazing failure) where the brazing material does not wet, which cause a decrease in joint strength and leakage failure, may occur. Even if the thickness of the nickel plating exceeds 3.0 μm, no further improvement effect of wettability can be obtained. Also, this is because excessive nickel plating forms compounds with active metals due to the excessive thickness of the nickel plating.

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

[0018] Copper and silver used as brazing metals have relatively low melting points as metals and are easily melted at temperatures suitable for brazing. Also, when copper and silver are alloyed, the melting point becomes even lower. Since the melting point of the alloyed copper and silver is lower than the melting point of the metal component used for brazing, there is an advantage that the metal component can be joined without being melted. Also, copper and silver are excellent in the fluidity and penetrability required for brazing and easily penetrate between components using capillary action. Furthermore, copper and silver contribute to the strength and durability of the joint portion after brazing. When copper and silver cool after brazing, stress between the ceramics and the metal component is less likely to occur, so cracks and deformation are less likely to occur in the joint portion. Also, they are excellent in thermal conductivity and electrical conductivity and are less likely to affect the functionality of the joint portion after brazing.

[0019] The active metal reacts with ceramics having poor wettability with metals to reduce the interfacial energy, thereby improving the wettability. When the wettability improves, the brazing material easily penetrates into the gaps between the components, and the bonding strength is improved. Also, the active metal forms a metal bond between the atoms of the base material and the brazing material to generate a solid solution at the bonding interface, contributing to the strength and durability of the joint portion. The active metal easily reacts with nickel to form a nickel-active metal compound. For this reason, the nickel contained in the metal component or the nickel plating formed on the surface of the metal component easily reacts with the active metal to form a nickel-active metal compound. Since this nickel-active metal compound is likely to react with the atmosphere of external air such as hydrogen and become brittle, there is a possibility of causing a decrease in bonding strength and a leak defect.

[0020] The low melting point metal has a lower melting point than other elements contained in the bonding layer. 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 those of other metals contained in the bonding layer, such as silver (961 °C), copper (1085 °C), titanium (1666 °C), zirconium (1852 °C), hafnium (2233 °C), etc. Therefore, when heat-treated, the low melting point metal has the characteristic of diffusing faster than other metals. By diffusing faster than nickel or reactive metals, the added low melting point metal reacts with copper or silver to form a bonding layer and prevents the nickel-reactive metal compound from depositing on the surface of the bonding layer. Also, the low melting point metal is added to the reactive metal solder paste. This is because when added to a solder paste composed of silver and copper, the melting point of the silver-copper alloy becomes low and it melts and solidifies first.

[0021] The ratio of the low melting point metal contained in the reactive metal solder component is 5 to 15 mass%. If the amount of the low melting point metal is less than 5 mass%, the diffusion into the solder layer becomes insufficient, and the effect of preventing the nickel-reactive metal compound from depositing on the outermost surface of the bonding layer cannot be obtained. On the contrary, if the ratio of the low melting point metal is more than 15 mass%, the proportion of silver or copper, which is the main component of the solder, decreases, and the functions such as mechanical properties of the bonding layer may deteriorate.

[0022] Fig. 4 shows an example of a cross-section of a joint portion of a ceramic sealing component according to an embodiment which is an enlarged view of portion B in Fig. 3. 5 is an active metal layer mainly composed of an active metal (hereinafter, referred to as "active metal layer"). The active metal layer 5 exists on the surface of the ceramic component 3 and contributes to the bonding between the ceramic and the metal. 6 is a brazing material layer composed of silver, copper, and a low melting point metal (hereinafter, referred to as "brazing material layer"). The brazing material layer 6 exists between the active metal layer 5 and the metal component 2 in the vicinity of the end face of the metal component 2 and contributes to the bonding between the active metal layer 5 and the metal component 2. Further, the brazing material layer 6 forms a meniscus at the location on the side surface of the metal component 2 to improve the bonding strength. For this reason, the brazing material layer 6 forming the meniscus forms the outermost surface of the brazing material layer (hereinafter, "the outermost surface of the brazing material layer") in contact with the external atmosphere. The outermost surface 61 of the brazing material layer is composed of silver, copper, and a low melting point metal. This is because, as in the manufacturing method described later, the low melting point metal printed on the ceramic side is heat-treated and diffuses to the outermost surface 61 of the brazing material layer. 7 is a nickel-active metal compound. As in the manufacturing method described later, the active metal printed on the ceramic side reacts with the nickel plating layer formed on the surface of the metal component 2 to form a nickel-active metal compound mainly composed of nickel and the active metal (hereinafter referred to as "nickel-active metal compound"). The fact that nickel and the active metal are the main components means that nickel and the active metal contain 50% by mass or more. For this reason, the nickel-active metal compound may contain silver, copper, a low melting point metal, and the like. As described above, since the diffusion speed of the added low melting point metal is fast and it reaches the outermost surface 61 of the brazing material layer first, the nickel-active metal compound 7 exists inside the outermost surface 61.

[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 and hydrogen and become brittle, possibly reducing the airtightness and bonding strength.

[0024] The method for measuring the distance L between the outermost surface 61 of the brazing material layer and the nickel-active metal compound 7 is determined by observing the cross-section of the joint. Briefly, the distance is determined by the element distribution. The cross-section of the joint as shown in Fig. 4 is color-mapped for nickel and the active metal using an energy dispersive X-ray fluorescence analyzer (EDX). The overlapping part of nickel and the active metal is the nickel-active metal compound, and the distance from the outermost surface can be determined by measurement.

[0025] When the boundary of the nickel-active metal compound is unclear, mass spectrometry by X-rays can be performed across the boundary for measurement. Fig. 5(a) is a diagram schematically showing the mass % of the constituent elements when measuring the distance L from the D1 direction for part C in Fig. 4. The mass % is measured for the constituent elements using an energy dispersive X-ray fluorescence analyzer (EDX). It shows the distribution of the mass % of silver, copper, active metal, low melting point metal, and nickel constituting the brazing material layer 6 from the outside (the part exposed to the atmosphere such as air or gas of the ceramic metal circuit component) to the inside (inside the joint layer). The minimum value (zero) of the mass % is the part where the observed element does not exist, and the mass % increases as the observed element exists. The location where the mass % of any metal element exceeds 2% is defined as the location of the outermost surface L1. Fig. 5(b) is an enlarged view of part D in Fig. 5(a). Also, L2, which is the boundary between the brazing material layer 6 and the nickel-active metal compound, is defined as the location where the mass % of nickel becomes 20% or more. Therefore, the distance L is the distance between L1 and L2.

[0026] Fig. 6 shows a process diagram of the manufacturing method of the ceramic sealing component according to the embodiment. Fig. 6(a) is a cross-sectional view of the ceramic component 3. In Fig. 6(a), chamfers are formed on the outer peripheral part and the inner peripheral part of the ceramic component 3. Although it is possible to obtain the ceramic sealing component even without the formation of chamfers, ceramics are prone to chipping due to external impacts and the like, and chamfering is effective for preventing chipping.

[0027] Fig. 6(b) shows the state of an active metal paste printed component in which the active metal brazing material paste 8 is printed and dried on the ceramic component 3. The surface of the active metal brazing material paste 8 before bonding is substantially flat in order to print the paste on the end face of the ceramic component which is flat. Also, in Fig. 6(b), the active metal brazing material paste 8 is printed only on the flat portion at the end, but it is also possible to print the active metal brazing material paste 8 up to the chamfered portion.

[0028] The active metal brazing material paste 8 is obtained by adding an organic binder and an organic solvent to a metal powder mixture containing one or more brazing metal materials of copper and silver, one or more active metals selected from active metals such as titanium, zirconium, and hafnium, and one or more low melting point metals selected from low melting point metals such as indium, tin, bismuth, antimony, and zinc. The organic binder is not particularly limited as long as it burns out during the drying process or the bonding process. As a preferable example, ethyl cellulose can be mentioned. The organic solvent is not particularly limited as long as it burns out during the drying process or the firing process. As a preferable example, terpineol and butyl carbitol can be mentioned. The active metal brazing material paste is prepared by mixing the active metal powder and the brazing metal powder and then mixing them with the organic binder and the organic solvent. Also, the ratio of the active metal contained in the active metal brazing material component is 0.1 to 15% by mass, preferably 0.5 to 10% by mass.

[0029] The printing thickness of the active metal brazing material paste is preferably 10 to 30 μm. If the printing thickness is less than 10 μm, the thickness of the active metal brazing material layer may vary, reducing the bonding strength. On the other hand, if it exceeds 30 μm, no further effect can be obtained. Also, the paste is printed on the end face of the ceramic component with a uniform thickness by a screen printing method or the like. If the printing thickness is non-uniform, the active metal brazing material will be excessive in the thick part, forming a brazing material accumulation and causing cracks due to thermal stress. Also, in the thin part, leakage defects will occur due to insufficient brazing material. Therefore, the difference between the thick part and the thin part of the printing thickness is preferably 5 μm or less.

[0030] Figure 6(c) shows the state of a brazing paste printed part in which the brazing paste 9 is printed and dried on the surface of the dried active metal paste 8 in Figure 6(b). The brazing paste 9 is composed of a metal component that has good wettability with the metal part and the active metal brazing filler metal. The brazing filler metal most commonly used for joining ceramic parts and metal parts is silver brazing filler metal. Silver brazing filler metal mainly consists of silver and copper, but may also contain other metal components such as zinc and nickel. There is a 72% silver - 28% copper silver brazing filler metal (BAg - 8) that is often used for joining ceramic parts and metal parts. In BAg - 8 according to "Silver Brazing Filler Metal (JIS Z3261:1998)", silver (Ag) is 71 - 73%, copper (Cu) is 27 - 29%, and the total of other elements is 0.15% or less. The brazing paste is prepared by adding an organic binder and an organic solvent to a mixture of brazing filler metal powder. The organic binder is not particularly limited as long as it burns out during the drying process or the joining process. A preferred example is ethyl cellulose. The organic solvent is not particularly limited as long as it burns out during the drying process or the firing process. Preferred examples 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.

[0031] The printing thickness of the brazing paste is preferably 70 - 300 μm. If the printing thickness is less than 70 μm, the thickness of the brazing filler metal layer may vary, reducing the joining strength. On the other hand, if it exceeds 300 μm, no further effect can be obtained. Also, the paste is printed on the end face of the ceramic part with a uniform thickness by a method such as screen printing. If the printing thickness is non - uniform, the active metal brazing filler metal will be excessive in the thick part, forming a brazing filler metal pool and causing cracks due to thermal stress. Also, in the thin part, leakage defects will occur due to insufficient brazing filler metal. Therefore, the difference in printing thickness between the thick part and the thin part is preferably 20 μm or less.

[0032] The active metal solder paste 8 contains an active metal and generates a compound that easily reacts with nickel and embrittles. Therefore, after bonding, it is preferable that the solder paste 9 covers the entire surface of the active metal solder. When printing by overlapping with the same printing pattern as the active metal solder paste 8, by making the viscosity of the solder paste 9 lower than the viscosity of the active metal paste, it is possible to spread during printing and cover the entire surface. Also, by making the printing pattern of the solder paste 9 larger (wider) than the printing pattern of the active metal solder paste, it is possible to print so as to cover the entire surface of the active metal solder layer. If the printing pattern is made too large, the solder paste 9 will gather on the active metal solder layer and metal parts without reacting with the ceramic parts during the heat treatment. At this time, if it accumulates in lumps around the active metal solder layer and metal parts, it will cause stress concentration. For this reason, when enlarging the printing pattern of the solder paste 9, it is preferable to enlarge it within a range of 0.1 mm or less than the printing pattern of the active metal solder paste 8.

[0033] Figure 6(d) shows a state in which the metal part 2 is installed on the surface of the printed and dried solder paste 6 of the solder paste printed part. When joining a plurality of metal parts 2 as shown in Figure 2, they are installed simultaneously. Heat treatment is performed in the installed state to join the metal parts 2.

[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 is a diagram showing an example of the heat treatment profile, where the vertical axis represents temperature and the horizontal axis represents time. Since the primary heating temperature T1 needs to melt the low melting point metal, it is set to a temperature higher than the melting point of the low melting point metal. Also, the hold time at the primary heating temperature T1 is preferably 10 to 30 minutes for the low melting point metal to diffuse throughout the bonding layer. If the hold time is shorter than 10 minutes, the low melting point metal will not diffuse throughout, and there will be no effect of preventing the precipitation of nickel-active metal compounds on the outermost surface of the bonding layer. Also, even if it is made longer than 30 minutes, no further effect can be obtained.

[0035] Also, the difference (T2 - T1) between the primary heating temperature T1 and the secondary heating temperature T2 is 120°C or less. Since the secondary heating temperature T2 is for heating in a state where the low-melting metal has diffused due to the primary heating temperature T1, the melting temperature of the solder paste is lower than normal. For this reason, if the difference (T2 - T1) between the primary heating temperature T1 and the secondary heating temperature T2 is greater than 120°C and the secondary heating temperature T2 is high, the solder paste spreads on the surface of the metal part 2 and no meniscus is formed. If no meniscus is formed, the bonding strength of the metal part may decrease. Also, the keep time of the secondary heating temperature T2 is 1 to 10 minutes for melting the solder. If the keep time is shorter than 1 minute, sufficient heating cannot be obtained for the solder to melt. Also, even if it is made longer than 10 minutes, no further effect can be obtained.

[0036] Figure 6(e) shows the state where the metal parts 2 are joined. The bonding layer 4 climbs up the side surface of the metal part 2 to form a strong bonding state. In this way, by covering the side surface of the metal part 2 with the bonding layer 4, high bonding strength can be achieved and sealing without leakage inside and outside the part is possible.

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

[0038] An example of the ceramic part 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 is likely to have chips or cracks at the corners due to external impacts or the like. For this reason, it is preferable to chamfer the outer peripheral part and the inner peripheral part of the end face. The chamfering shape is, for example, C chamfering or R chamfering, and the chamfering size is preferably 0.1 to 2 mm.

[0039] The materials of the metal parts according to the embodiment include iron and iron alloys, copper and copper alloys, iron-nickel alloys, tungsten, molybdenum, etc. An example of the shape of the metal parts according to the embodiment is a substantially cylindrical shape. For example, in the case of Figure 2, the height is 20 mm, the outer diameter is 46 mm, and the inner diameter is 44 mm. These metal parts are nickel-plated with 0.5 to 3.0 μm for improving corrosion resistance and wettability.

[0040] The form of the active metal brazing filler metal and the brazing filler metal is a paste. For sheets and wires, after melting the active metal brazing filler metal and processing it into sheet or wire shapes, a process is required to further process it into predetermined dimensions according to the product shape. In contrast, for the paste, although there is a process for manufacturing the paste, it is excellent in handling, such as printing it on the necessary parts according to the product shape. Also, if the amount of the active metal brazing filler metal is too small, brazing failure, which is an unjoined part, will occur, and if it is too large, brazing accumulation will occur, causing stress fracture. Therefore, it is possible to adjust the amount of the paste used according to the joining area.

[0041] The active metal brazing filler metal paste is prepared by adding an organic binder and an organic solvent to a mixture of active metal powder and brazing filler metal powder. The organic binder is not particularly limited as long as it burns out during the drying process or the joining process. A preferred example is ethyl cellulose. The organic solvent is not particularly limited as long as it burns out during the drying process or the firing process. Preferred examples include terpineol and butyl carbitol. The active metal brazing filler metal paste is prepared, for example, by crushing and mixing the active metal powder and the brazing filler metal powder, and then mixing them with the organic binder and the organic solvent. Also, the ratio of the active metal contained in the active metal brazing filler metal component is 0.1 to 15% by mass, preferably 0.5 to 10% by mass.

[0042] The printing thickness of the active metal solder paste is preferably 10 to 30 μm. If the printing thickness is less than 10 μm, the thickness of the active metal solder layer may vary, reducing the bonding strength. On the other hand, if it exceeds 30 μm, no further effect can be obtained. Also, the paste is printed on the end face of the ceramic component with a uniform thickness by a screen printing method or the like. If the printing thickness is non-uniform, the active metal solder paste will be excessive in the thick part, resulting in solder accumulation and cracks due to thermal stress. Also, in the thin part, leakage failure may occur due to insufficient active metal solder. Therefore, the difference in printing thickness between the thick part and the thin part is preferably 5 μm or less.

[0043] The paste printed on the ceramic component dries in the air or the like. If the drying temperature is low and the drying time is short, the solution component of the paste may not be sufficiently volatilized, and the remaining solution may volatilize during bonding, possibly generating voids. Conversely, if the drying temperature is high and the drying time is long, the oxidation of the paste surface may progress, and the bonding temperature may change. Therefore, the drying temperature is 50 to 100 °C, preferably 60 to 80 °C. Also, the drying time is 5 to 30 minutes, preferably 10 to 20 minutes.

[0044] The brazing paste is composed of a metal part and a metal with good wettability to the active metal brazing filler metal. The brazing filler metal most commonly used for joining ceramics and metal parts is silver brazing filler metal. Silver brazing filler metal mainly consists of silver and copper, but may also contain other metal components such as zinc and nickel. There is a silver brazing filler metal (BAg-8) composed of 72% silver - 28% copper, which is often used for joining ceramics and metal parts. In BAg-8 according to "Silver Brazing Filler Metal (JIS Z3261:1998)", silver (Ag) is 71 - 73%, copper (Cu) is 27 - 29%, and the total of other elements is 0.15% or less. The brazing paste is prepared by adding an organic binder and an organic solvent to a mixture of brazing filler metal powder. The organic binder is not particularly limited as long as it burns out during the drying process or the joining process. A preferable example is ethyl cellulose. The organic solvent is not particularly limited as long as it burns out during the drying process or the firing process. Preferable examples include terpineol and butyl carbitol. The brazing paste is prepared, for example, by pulverizing and mixing metal powders and then mixing them with an organic binder and an organic solvent.

[0045] The printing thickness of the brazing paste is preferably 70 - 300 μm. If the printing thickness is less than 70 μm, the thickness of the brazing filler metal layer may vary, reducing the joining strength. On the other hand, if it exceeds 300 μm, no further effect can be obtained. Also, the paste is printed on the end face of the ceramic part with a uniform thickness by a method such as screen printing. If the printing thickness is non-uniform, the brazing filler metal will be excessive in the thick part, forming a brazing filler metal pool and causing cracks due to thermal stress. Also, in the thin part, leakage defects will occur due to the exhaustion of the active metal brazing filler metal. Therefore, the difference in printing thickness between the thick part and the thin part is preferably 20 μm or less, and more preferably 15 μm or less.

[0046] The solder paste printed on the active metal solder layer dries in the atmosphere or the like. If the drying temperature is low and the drying time is short, the solution components of the paste may not be sufficiently volatilized, and the remaining solution may volatilize during bonding, possibly generating voids. Conversely, if the drying temperature is high and the drying time is long, the oxidation of the paste surface may progress, and the bonding temperature conditions may change. Therefore, the drying temperature is 50 to 100 °C, preferably 60 to 80 °C. Also, the drying time is 5 to 30 minutes, preferably 10 to 20 minutes.

[0047] Bonding is performed by placing a metal part on the dried paste surface and performing heat treatment after the solder paste dries. The heat treatment profile preferably has two-stage heating including primary heating and secondary heating at a temperature higher than the primary heating. The primary heating temperature T1 is 650 to 850 °C, preferably 700 to 800 °C. Also, the bonding time for the primary heating is preferably in the range of 10 to 30 minutes in the state where the primary heating temperature is reached. Also, for the secondary heating temperature T2 after the primary heating, the difference (T2−T1) from the primary heating temperature T1 is preferably 120 °C or less. Also, the bonding time for the secondary heating is preferably between 1 and 10 minutes in the state where the secondary heating temperature T2 is reached. As shown in Fig. 6(e), since the bonding layer 4 melts and spreads wet over the surface of the metal part 2, a bonding with sealing property is performed. If the bonding temperature is low and the bonding time is short, the active metal solder may not melt sufficiently and may not bond. Conversely, if the bonding temperature is high and the bonding time is long, the solder may melt too much and spread wet, possibly causing solder breakage or voids.

[0048] Also, the bonding atmosphere shall be non-oxidizing as required. Examples of the non-oxidizing atmosphere include a nitrogen atmosphere and a nitrogen-hydrogen atmosphere. By using a non-oxidizing atmosphere, oxidation of the bonding layer can be suppressed. Thereby, an improvement in bonding strength can be achieved. As the furnace used in the bonding process, a continuous furnace or a batch furnace is used. The continuous furnace is excellent in mass productivity, and the batch furnace is easy to control the temperature and atmosphere. Bonding is performed by heat-treating the parts in the above atmosphere for a predetermined time.

[0049] The thickness of the bonding layer for bonding the ceramic part and the metal part is preferably 80 μm or more. This is because, as described above, the bonding layer is formed from an active metal brazing material layer of 10 μm or more and a brazing material layer of 70 μm or more. Note that the thickness of the bonding layer at this time indicates the distance between the bonding surface of the metal part and the ceramic part. For example, in FIG. 6(e), the tip (end face) of the metal part 2 is a flat surface. In this case, the thickness of the bonding layer indicates the distance of the flat part of the metal part between the substantially central flat part of the metal part and the flat part of the ceramic part. Also, when the tip of the metal part 2 is bent into a flange shape and bonded to the ceramic part 3, the substantially central part of the bent flange part is taken as the thickness of the bonding layer. Further, when the tip of the metal part 2 is pointed like a U-shape or a V-shape, the distance between the pointed tip part and the ceramic surface is taken as the thickness of the bonding layer.

[0050] As described above, according to the method for manufacturing a ceramic sealed component in the embodiment of the present invention, a ceramic sealed component excellent in cost performance can be obtained while maintaining the airtight performance as a sealed component.

[0051] (Examples 1 to 8, Comparative Examples 1 to 8) Auxiliary agents of manganese oxide (MnO2), silicon oxide (silica: SiO2), and magnesium oxide (magnesia: MgO) were added to alumina to prepare a granulated powder having a composition of 92% by mass alumina. The granulated powder was molded by die pressing and sintered in air at 1500 °C to obtain a cylindrical ceramic part with an outer diameter of 50 mm, an inner diameter of 40 mm, a height of 50 mm, an outer diameter chamfer of 0.5 mm, and an inner diameter chamfer of 0.5 mm. Also, 3% by mass of a yttria (yttrium oxide: Y2O3) auxiliary agent was added to aluminum nitride (AlN) to prepare an aluminum nitride granulated powder. The granulated powder was molded by die pressing and sintered in nitrogen at 1800 °C to obtain a cylindrical ceramic part having the same dimensions as the alumina part.

[0052] The metal parts were press-worked into a cylindrical shape with an outer diameter of 46 mm, an inner diameter of 44 mm, and a height of 20 mm using iron, stainless steel (SUS304), and Kovar, to obtain metal parts as shown in Table 1. Nickel plating with the thickness shown in Table 1 was applied to the surface of the processed metal parts.

[0053] Next, the metal powder mixing ratio was prepared by mixing silver powder, copper powder, low melting point metal powder, and active metal powder in mass percentages as shown in Fig. 1. In Example 1, it was 30 mass% copper powder, 10 mass% indium powder, 2 mass% titanium, and the balance silver powder. In Example 1, it was denoted as Ag-30Cu-10In-2Ti in Table 1, and the same notation was used for other examples and comparative examples. The prepared metal powder was mixed with ethyl cellulose and terpineol and pasted with a kneader to prepare an active metal solder paste. An active metal paste with a thickness of 30 μm was printed by screen printing on the upper and lower ends (ring parts) of the ceramic parts using a 100-mesh screen with an outer diameter of 48 mm × inner diameter of 42 mm, and dried at 100°C in the air. The active metal solder paste was dried.

[0054] Next, the metal powder mixing ratio was prepared by mixing silver powder and copper powder at 72:28 in mass percentages, and pasted in the same manner as the active metal solder paste to prepare a silver solder paste. A solder paste with a thickness of 100 μm was printed by screen printing on the upper and lower ends (ring parts) of the ceramic parts with the active metal solder layer formed using a 100-mesh screen with an outer diameter of 48 mm × inner diameter of 42 mm, and dried at 100°C in the air. Next, the metal parts, ceramic parts, and metal parts were set in the jig in this order, and heated in a vacuum furnace under vacuum (1 × 10 -2 Pa or less) at the primary heating temperature T1 shown in Table 1 for 20 minutes and at the secondary heating temperature for 5 minutes to join the metal parts and the ceramic parts to produce a ceramic-sealed part.

[0055]

Table 1

[0056] As can be seen from Table 1, in the examples, the values of the nickel plating thickness, the ratio of the active metal brazing material paste, and the heating temperature difference (T2 - T1) were within the preferred ranges. On the other hand, in the comparative examples, they were outside the preferred ranges.

[0057] Next, the ceramic sealed component was cut at the central part as shown in Figure 2, and the joint part was polished as shown in Figure 3. Next, for the peripheral part of the joint part, surface analysis of the constituent elements was performed using an energy dispersive X-ray fluorescence analyzer (EDX). The position of D1 in Figure 4 was determined from the state of the surface analysis, and mass% analysis was performed. The joint distance L as shown in Figure 5 was obtained from the values of the mass% analysis. The obtained results are shown in Table 2.

[0058] Next, a hydrogen heating test was conducted to confirm brittleness from the external atmosphere. In the hydrogen heating test, the heat treatment was carried out in a nitrogen-hydrogen atmosphere with 20% hydrogen in a belt heating furnace at 400 °C or higher for 10 minutes as one heat treatment, and the ceramic sealed component was heat-treated 5 times. By visually observing the joint part after the heat treatment, those without a change in the surface color (discoloration) were judged as pass (〇), and those with discoloration (including partial discoloration such as spots) were judged as fail (×).

[0059] Next, the bonding strength was determined by pulling the upper and lower metal parts of the ceramic sealed component after the hydrogen heat treatment up and down with an Instron tensile testing machine.

[0060] Also, for the upper part of the ceramic sealed component after the hydrogen heat treatment, silicone was applied and suppressed with a circular jig made of Bytong rubber, and the lower part was fixed to a helium leak detector and sucked to conduct a helium leak test. The helium leak test was conducted in accordance with the vacuum spraying method (spray method) of the "Helium Leak Test Method" (JIS Z2331:2006). When no leak of 1×10 -9 Pa·m 3 / s or more occurred at a vacuum degree of 1.3 μPa, it was judged as pass (〇), and when a leak occurred, it was judged as fail (×).

[0061]

Table 2

[0062] As can be seen from Table 2, regarding the bonding distance L, in the examples, it was in a preferable range of 10 μm or more. This is because under the bonding conditions of the examples, the nickel-active metal compound prevents precipitation on the surface of the bonding layer due to diffusion of the low-melting metal or the like. On the other hand, in the comparative examples, some were outside the preferable range. This is because a barrier for preventing precipitation of the nickel-active metal compound was not formed.

[0063] Also, as can be seen from Table 2, regarding the hydrogen heating test, in the examples, discoloration was not observed. This is because a sufficient distance of the bonding distance L was obtained, and embrittlement by hydrogen did not occur. On the other hand, discoloration was observed in the comparative examples. This is because a sufficient distance of the bonding distance L was not obtained, and embrittlement by hydrogen occurred.

[0064] Also, as can be seen from Table 2, the bonding strength of the examples was a good value of 40 MPa or more. This is because under the bonding conditions of the examples, a strong bonding layer was formed and no embrittlement occurred even in the hydrogen heating test. In contrast, in the comparative examples, it was 25 MPa or less. This is because embrittlement progressed in the hydrogen heating test, leading to a decrease in the bonding strength.

[0065] Also, no leak failure occurred in the ceramic sealing component according to the examples in the helium leak test. This is because no embrittlement occurred even in the hydrogen heating test. In contrast, leak failure occurred in the comparative examples. This is because embrittlement progressed in the hydrogen heating test, and airtightness could not be maintained due to a decrease in the bonding strength.

[0066] As is clear from the results shown above, the examples showed an improvement in resistance to the external atmosphere compared to the comparative examples.

[0067] As described above, several embodiments of the present invention have been illustrated. However, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, changes, etc. can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and its equivalent scope. In addition, the above-described embodiments can be implemented in combination with each other.

Explanation of Reference Numerals

[0068] 1...Ceramic Sealing Component 2...Metal Component 3...Ceramic Component 4...Bonding Layer 5...Active Metal Layer 6...Solder Layer, 61...Outermost Surface of Solder Layer 7...Nickel-Active Metal Compound 8...Active Metal Solder Paste 9...Solder Paste

Claims

1. In 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, a compound of nickel and an active metal is formed in the joining layer, and a ceramic sealed component, characterized in that the distance between the compound and the surface of the joining layer is 10 μm or more.

2. The ceramic sealed component according to claim 1, wherein 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. The ceramic sealed component according to claim 1 or claim 2, wherein the metal component is one or more metal components selected from iron, an iron alloy, an iron-nickel-based alloy, copper, and a copper alloy.

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

5. The ceramic sealed component according to claim 1 or claim 2, wherein the ceramic component is alumina, aluminum nitride, silicon nitride, or alumina added with zirconia.

6. In a method for manufacturing a ceramic sealed component for joining a ceramic component and a metal component, a step of printing and drying an active metal paste containing at least copper, an active metal, and a low melting point metal on the ceramic component to obtain an active metal paste printed component; a step of printing and drying a brazing material paste containing at least silver and copper on the surface of the active metal paste printed component to obtain a brazing material paste printed component; and a joining step of installing a metal component on the brazing material paste printed component and performing a heat treatment. A method for manufacturing a ceramic sealed component, characterized by comprising the above steps.

7. The method for manufacturing a ceramic sealed component according to claim 6, wherein the heat treatment consists of a primary heating temperature and a secondary heating temperature higher than the primary heating temperature, and the difference (T2 - T1) between the primary heating temperature T1 and the secondary heating temperature T2 is 120°C or less.

8. The method for manufacturing a ceramic sealed component according to claim 6 or claim 7, characterized in that the printed thickness of the active metal paste is 30 μm or less, and the thickness of the brazing material paste is 70 μm or more.

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