Ceramic feed-through manufacturing method and feed-through

Abstract

The invention discloses a manufacturing method of a ceramic feed-through. The manufacturing method comprises the following steps: a, manufacturing a ceramic part with a through hole; b, a metal ceramic part matched with the through hole of the ceramic part in size is manufactured; c, manufacturing glass brazing filler metal; d, the ceramic part and the metal ceramic part are assembled, and brazing filler metal is preset in the through hole assembling gap; e, putting the combined metal ceramic part and ceramic part into a heating furnace protected by a neutral or reducing atmosphere, carrying out heating treatment according to a specific temperature system, and taking out the metal ceramic part and ceramic part after the temperature is reduced to room temperature; and f, the size is corrected through grinding. According to the method, the low-connection-stress ceramic feed-through can be obtained, so that the method is suitable for manufacturing the large-size ceramic feed-through piece.

Description

Technical Field

[0001] The invention belongs to the field of feedthroughs, and in particular relates to a ceramic feedthrough manufacturing method and a ceramic feedthrough. Background Art

[0002] In some power and electronic systems, it is often necessary to lead the circuit out or into a closed space. This structure for leading the circuit out or out is called a feedthrough. Feedthroughs are mainly composed of a conductor core and an insulating layer wrapped around the core. Feedthroughs often need to have good sealing and electrical continuity. In some extreme applications, feedthroughs used for electrical connection of internal and external equipment in reactors also need to have good high temperature resistance, corrosion resistance, and resistance to ionizing radiation damage. Most traditional feedthroughs use organic material swaging sealing technology, that is, organic polymers are used as insulating layers. However, organic materials have poor temperature resistance, and their electrical and mechanical properties will decrease under high temperature, high pressure, and strong radiation environments, thereby reducing the reliability of electrical penetrations made of such swaging seals. Therefore, using ceramic materials with excellent high temperature stability as the insulating layer of feedthroughs has become a consensus in the current design of electrical penetrations. At present, ceramic feedthrough designs still mainly use metals such as molybdenum, copper, and kovar as the inner core conductive materials. It is necessary to add one or more transition layers between the metal and the ceramic and seal them by brazing to ensure the sealing of the feedthrough. Due to the weak corrosion resistance of metals and the large difference in expansion coefficients between metals, ceramics and transition layers, sealing stress is generated. It is difficult to ensure that there will be no problems such as interface failure and decreased airtightness when the temperature and pressure rise abnormally.

[0003] In previous work, we proposed a conductive multiphase ceramic with a ceramic material similar to the insulating layer as the core, and co-sintered to form a full ceramic feedthrough material with a coaxial line structure through gradient material design. It can completely avoid the safety problems caused by the failure of the core / insulating layer interface and greatly extend the service life of the feedthrough. It has excellent high temperature resistance, corrosion resistance, and resistance to ionizing radiation damage, which improves the safety factor of electrical penetrations. However, during the co-firing process, there are inevitably differences in the sintering shrinkage process between the conductive multiphase ceramic and the insulating ceramic, which makes the manufacturing of the conductive multiphase ceramic-insulating ceramic composite feedthrough difficult. It is often necessary to finely control the co-sintering process according to the sintering shrinkage process of the conductive multiphase ceramic and the insulating ceramic to reduce the risk of cracking. In large-sized feedthroughs, the cracking problem caused by the inconsistency of the sintering shrinkage process will be particularly serious, so the co-sintering method is not suitable for the manufacture of large-sized feedthroughs. Summary of the invention

[0004] Based on the above problems, the present invention provides a ceramic feedthrough manufacturing method and a ceramic feedthrough, which can obtain a ceramic feedthrough with low connection stress, so that it is suitable for the manufacture of large-sized ceramic feedthroughs.

[0005] To achieve the purpose, the specific technical solution of the present invention is as follows:

[0006] A method for manufacturing a ceramic feedthrough, the manufacturing method specifically comprising the following steps:

[0007] a. Manufacturing ceramic parts with through holes;

[0008] b. Manufacturing metal ceramic parts that match the through-hole size of ceramic parts;

[0009] c. Grind the raw material of glass solder into powder, make the powder into paste solder or compact the powder into ring solder;

[0010] d. Evenly apply paste solder on the surface of the metal ceramic part, and place the metal ceramic part into the through hole of the ceramic part; or pre-place the ring solder in the assembly gap between the metal ceramic part and the ceramic part;

[0011] e. Place the assembled metal ceramic parts and ceramic parts in a heating furnace with atmosphere protection, heat them according to a specific temperature system, and take them out after the temperature drops to room temperature;

[0012] f. Correct the size by grinding.

[0013] In some embodiments, in step b, the metal ceramic part is a mixture of the ceramic part in step a and metal.

[0014] In some embodiments, in step b, the volume content of metal in the metal ceramic part is between 7% and 60%.

[0015] In some embodiments, the thermal expansion coefficient of the metal ceramic part in step b is consistent with the thermal expansion coefficient of the ceramic in step a.

[0016] In some embodiments, step c specifically includes adding a glass binder to make the powder into a paste solder, wherein the thermal expansion coefficient of the glass binder is consistent with the thermal expansion coefficient of the ceramic and the metal ceramic.

[0017] In some embodiments, in step e, the specific temperature regime is specifically to maintain the heating time in the range of 0.8Tg to 0.95Tg for more than 6 hours to eliminate the stress in the glass, where Tg is the glass transition temperature of the glass binder.

[0018] In a second aspect, the present application provides a ceramic feedthrough manufactured according to the aforementioned ceramic feedthrough, wherein the feedthrough has ceramic as an insulator on the outside and metal ceramic as a conductor on the inside, and the ceramics and metal ceramics are connected together by glass adhesive.

[0019] In some embodiments, the resistivity of the insulator may be better than 1010Ω·cm, and the resistivity of the conductor may be lower than 10-3Ω·cm.

[0020] In some embodiments, there is an offset angle between the inner hole of the ceramic part and the outer diameter of the metal ceramic; or, the inner hole of the ceramic part has a chamfer. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is the feedthrough in Example 1;

[0022] Figure 2 is the feedthrough in Example 2;

[0023] In the figure, 1. is a ceramic part, and 2. is a metal ceramic part. Specific implementation methods

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] In a first aspect, the present application provides a method for manufacturing a ceramic feedthrough, the manufacturing method specifically comprising the following steps:

[0027] a. Manufacturing a ceramic part 1 having a through hole;

[0028] b. Manufacturing a metal ceramic part 2 having a through-hole size matching that of the ceramic part 1;

[0029] c. Grind the raw material of glass solder into powder, make the powder into paste solder or compact the powder into ring solder;

[0030] d. Evenly apply the paste solder on the surface of the metal ceramic part 2, and place the metal ceramic part 2 into the through hole of the ceramic part 1; or pre-place the ring solder in the assembly gap between the metal ceramic part 2 and the ceramic part 1;

[0031] e. Place the combined metal ceramic part 2 and the ceramic part 1 into a heating furnace with atmosphere protection, heat them according to a specific temperature system, and take them out after the temperature drops to room temperature;

[0032] f. Correct the size by grinding.

[0033] The present invention discloses a ceramic feedthrough manufacturing method, which utilizes ceramic as an external insulator and metal ceramic as an internal conductor, and connects the ceramic and the metal ceramic together through a high-temperature molten glass adhesive.

[0034] In some embodiments, in step b, the metal ceramic part 2 is a mixture of the ceramic part 1 in step a and metal.

[0035] The metal component is used to realize the electrical conductivity of the metal ceramic, while the ceramic component is used to ensure the mutual diffusion and penetration ability of the metal ceramic and the glass binder.

[0036] In some embodiments, in step b, the volume content of metal in the metal ceramic part 2 is between 7% and 60%.

[0037] This embodiment ensures that the metal ceramic has excellent conductivity and the ability to diffuse and penetrate with the glass binder. Conductivity is the basic performance of feedthrough. The premise of the conductivity of metal ceramic is that the metal components therein can form a connected network. Experimental results show that this requires the volume content of the metal to be greater than 7%. The ability to diffuse and penetrate with the glass binder is to ensure the connectivity between ceramics and metal ceramics. Experimental results show that when the ceramic component is higher than 30%, the glass binder has excellent adhesion to the metal ceramic.

[0038] In some embodiments, the thermal expansion coefficient of the metal ceramic part 2 in step b is consistent with the thermal expansion coefficient of the ceramic in step a.

[0039] In this embodiment, other oxides or metals may be appropriately added to the metal ceramic to make the thermal expansion coefficient of the metal ceramic as consistent as possible with that of the ceramic, thereby avoiding the generation of large stress and cracking during the cooling process after heating in step e.

[0040] In some embodiments, step c specifically includes adding a glass binder to make the powder into a paste solder, wherein the thermal expansion coefficient of the glass binder is consistent with the thermal expansion coefficient of the ceramic and the metal ceramic.

[0041] In this embodiment, glass binders are added to make the powder into paste-like solder. By adjusting the raw material formula of the glass solder, the thermal expansion coefficient of the glass solder is made as consistent as possible with that of ceramics and metal ceramics, thereby avoiding the generation of large stress and cracking during the cooling process after heating in step e.

[0042] In some embodiments, in step e, the specific temperature regime is specifically to maintain the heating time in the range of 0.8Tg to 0.95Tg for more than 6 hours to eliminate the stress in the glass, where Tg is the glass transition temperature of the glass binder.

[0043] Annealing is an important step in the glass manufacturing process, the purpose of which is to eliminate stress in the glass and prevent glass cracking. The annealing temperature is generally set between 0.8Tg and 0.95Tg, which not only ensures that the glass adhesive has a certain creep performance, but also eliminates the stress introduced by the nearly step-like shrinkage of the glass adhesive near Tg during the cooling process.

[0044] In a second aspect, the present application provides a ceramic feedthrough manufactured according to the aforementioned ceramic feedthrough, wherein the feedthrough has ceramic as an insulator on the outside and metal ceramic as a conductor on the inside, and the ceramics and metal ceramics are connected together by glass adhesive.

[0045] Ceramic is used as an external insulator and metal ceramic is used as an internal conductor. The ceramic and metal ceramic are connected together by a high-temperature molten glass adhesive, and the high-temperature molten glass adhesive is used to fill the gap between the ceramic and the metal ceramic to achieve sealing.

[0046] The ceramic feedthrough of the present application has the advantages of high temperature resistance, corrosion resistance, and resistance to ionizing radiation damage, as well as low connection stress and is suitable for the manufacture of large-size ceramic feedthroughs.

[0047] In some embodiments, the resistivity of the insulator may be better than 1010Ω·cm, and the resistivity of the conductor may be lower than 10-3Ω·cm.

[0048] In some embodiments, there is an offset angle between the inner hole of the ceramic component 1 and the outer diameter of the metal ceramic; or, the inner hole of the ceramic component 1 has a chamfer.

[0049] There is a 2° offset angle between the inner hole of ceramic part 1 and the outer diameter of metal ceramic to increase the fit between metal ceramic part 2 and ceramic part 1. Alternatively, the inner hole of ceramic part 1 is designed to have a C1 chamfer, which is not only used for assembly needs, but also can store overflowed glass solder.

[0050] Example 1

[0051] like Figure 1 As shown. A 95 alumina ceramic (mass percentage of 93.7% Al2O3, 2.1% SiO2, 3.3% CaO, 0.8% MgO and 0.1% other components) is used as the insulating layer, and its average thermal expansion coefficient in the range of room temperature to 1000°C is 8.3×10-6 / °C. A 95 alumina ceramic with a volume content of 15% Mo is used as the conductive ceramic core, and its average thermal expansion coefficient in the range of room temperature to 1000°C is 7.9×10-6 / °C. Feedthrough Figure 1 As shown, there is an offset angle of 2° between the inner hole of the ceramic part 1 and the outer diameter of the metal ceramic to increase the fit between the metal ceramic part 2 and the ceramic part 1 .

[0052] The mass percentage of each component in the raw material of glass solder is 62% SiO2, 7% Al2O3, 7% CaO, 5% MgO, 14% B2O3, 3% Na2O, 2% K2O. It is heated to 1400℃ in an alumina crucible to melt, stirred evenly and poured into water, taken out and ground into 200 mesh powder for use. DSC analysis shows that the Tg of the glass binder is equal to 602℃. The glass binder powder is mixed in a ratio of 100g:50ml water, 3% PVA is added, and the slurry after stirring evenly is applied to the outer cylinder of the metal ceramic. After the glass binder slurry is dried, the metal ceramic part 2 is placed in the ceramic part 1.

[0053] Place the combined metal ceramic part 2 and ceramic part 1 in a Mo wire heating furnace. Figure 1 Place in the direction shown, with hydrogen as the protective atmosphere. Heat according to the temperature system listed in the following table:

[0054] Table 1 Correspondence between sieve mesh number and particle size

[0055] Temperature range Room temperature~1400℃ 1400℃ 1400℃～560℃ 560℃ 560℃~Room temperature time 6 hours 0.5 hours 4 hours 6 hours 6 hours

[0056] After the temperature drops to room temperature, grinding is used to remove the glass binder overflowing from the surface of the metal ceramic and ceramic.

[0057] The resistivity of the outer insulator is equal to 8×1013Ω·cm, and the resistivity of the inner part is equal to 7×10-4Ω·cm.

[0058] Example 2

[0059] like Figure 2 As shown. A zirconia-toughened alumina ceramic (mass percentage of 88.4% Al2O3, 5.6% ZrO2, 1.8% SiO2, 3.2% CaO, 0.9% MgO and 0.1% other components) is used as the insulating layer, and its average thermal expansion coefficient in the range of room temperature to 1000°C is 8.7×10-6 / °C. A zirconia-toughened alumina ceramic with an added volume content of 19% W is used as the conductive ceramic core, and its average thermal expansion coefficient in the range of room temperature to 1000°C is 8.1×10-6 / °C. Feedthrough as shown Figure 2 As shown, the inner hole of the ceramic component 1 has a chamfer C1, which is not only used for assembly requirements, but also can store overflowed glass solder.

[0060] The mass percentage of each component in the raw material of glass solder is 65% SiO2, 3% Al2O3, 6% CaO, 3% MgO, 15% B2O3, 4% Na2O, 4% K2O. Heat it to 1400℃ in an alumina crucible to melt, stir it evenly and pour it into water, take it out and grind it into 200 mesh powder for use. DSC analysis shows that the Tg of glass binder is equal to 524℃. Mix the glass binder powder in a ratio of 100g:50ml water, add 3% PVA, and apply the slurry after stirring evenly on the contact surface between metal ceramic and ceramic. After the glass binder slurry is dried, place the metal ceramic part 2 in the ceramic part 1.

[0061] Place the combined metal ceramic part 2 and ceramic part 1 in a Mo wire heating furnace. Figure 1 Place in the direction shown, with hydrogen as the protective atmosphere. Heat according to the temperature system listed in the following table:

[0062] Table 1 Correspondence between sieve mesh number and particle size

[0063] Temperature range Room temperature~1400℃ 1200℃ 1200℃～480℃ 480℃ 480℃~Room temperature time 6 hours 0.5 hours 4 hours 6 hours 6 hours

[0064] After the temperature drops to room temperature, grinding is used to remove the glass binder overflowing from the surface of the metal ceramic and ceramic.

[0065] The resistivity of the external insulator is equal to 4×1013Ω·cm, and the resistivity of the internal is equal to 6×10-4Ω·cm.

[0066] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred implementation methods, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A method for manufacturing a ceramic feedthrough, characterized in that: The manufacturing method specifically comprises the following steps: a. Manufacturing ceramic parts with through holes; b. Manufacturing a metal ceramic part having a through-hole size matching that of the ceramic part; c. Grind the raw material of glass solder into powder, make the powder into paste solder or compact the powder into ring solder; d. uniformly coating the solder paste on the surface of the metal ceramic part, and placing the metal ceramic part into the through hole of the ceramic part; or pre-placing the ring solder in the assembly gap between the metal ceramic part and the ceramic part; e. placing the combined metal ceramic parts and the ceramic parts into a heating furnace with an atmosphere protection, heating them according to a specific temperature system, and taking them out after the temperature drops to room temperature; f. Correct the size by grinding.

2. A method for manufacturing a ceramic feedthrough as claimed in claim 1, characterized in that: In step b, the metal ceramic part is a mixture of the ceramic part and metal in step a.

3. A method for manufacturing a ceramic feedthrough as claimed in claim 1, characterized in that: In step b, the volume content of metal in the metal ceramic part is between 7% and 60%.

4. A method for manufacturing a ceramic feedthrough as claimed in claim 1, characterized in that: The thermal expansion coefficient of the metal ceramic part described in step b is consistent with the thermal expansion coefficient of the ceramic described in step a.

5. The method for manufacturing a feedthrough as claimed in claim 1, characterized in that Step c specifically includes adding a glass binder to make the powder into a paste solder, wherein the thermal expansion coefficient of the glass binder is consistent with the thermal expansion coefficient of the ceramic and the metal ceramic.

6. A method for manufacturing a ceramic feedthrough as claimed in claim 1, characterized in that: In step e, the specific temperature regime is specifically to maintain the heating time in the range of 0.8Tg to 0.95Tg for more than 6 hours to eliminate the stress in the glass, where Tg is the glass transition temperature of the glass binder.

7. A ceramic feedthrough manufactured according to any one of claims 1 to 6, characterized in that: The outside of the feedthrough is made of ceramic as an insulator, and the inside is made of metal ceramic as a conductor. The ceramics and metal ceramics are connected together by glass adhesive.

8. The ceramic feedthrough according to claim 7, characterized in that The resistivity of an insulator can be better than 1010Ω·cm, and the resistivity of a conductor can be lower than 10-3Ω·cm.

9. The ceramic feedthrough according to claim 7, characterized in that There is an offset angle between the inner hole of the ceramic part and the outer diameter of the metal ceramic; or, the inner hole of the ceramic part has a chamfer.

Images