CN111192797A - High-voltage large-current fuse sealing packaging method - Google Patents
High-voltage large-current fuse sealing packaging method Download PDFInfo
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- CN111192797A CN111192797A CN202010074000.1A CN202010074000A CN111192797A CN 111192797 A CN111192797 A CN 111192797A CN 202010074000 A CN202010074000 A CN 202010074000A CN 111192797 A CN111192797 A CN 111192797A
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- brazing
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H69/00—Apparatus or processes for the manufacture of emergency protective devices
- H01H69/02—Manufacture of fuses
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F7/00—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression
- B22F7/02—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite layers
- B22F7/04—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite layers with one or more layers not made from powder, e.g. made from solid metal
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
- C23C28/02—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D only coatings only including layers of metallic material
- C23C28/023—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D only coatings only including layers of metallic material only coatings of metal elements only
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C30/00—Coating with metallic material characterised only by the composition of the metallic material, i.e. not characterised by the coating process
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D3/00—Electroplating: Baths therefor
- C25D3/02—Electroplating: Baths therefor from solutions
- C25D3/12—Electroplating: Baths therefor from solutions of nickel or cobalt
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D7/00—Electroplating characterised by the article coated
- C25D7/04—Tubes; Rings; Hollow bodies
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H85/00—Protective devices in which the current flows through a part of fusible material and this current is interrupted by displacement of the fusible material when this current becomes excessive
- H01H85/0078—Security-related arrangements
Abstract
The invention belongs to a fuse sealing method, and aims to solve the technical problems that sealing structures are difficult to design and the sealing effect is poor because two ends of a fuse are sealed by sealing rings or glue pouring in the prior art, and the conventional welding method in welding sealing is adopted, and the damage to fillers in a ceramic tube and the ceramic tube is easily caused because the instantaneous temperature is high during welding.
Description
Technical Field
The invention belongs to a fuse sealing method, and particularly relates to a high-voltage high-current fuse sealing and packaging method.
Background
The high-voltage large-current fuse is a device which can rapidly generate heat to rapidly fuse a melt when the current exceeds a rated value, thereby rapidly protecting a high-voltage circuit or a high-voltage system from short circuit, and is widely applied to the fields of electric power systems, charging power supplies, batteries, new energy automobiles, electric locomotives, ships and submarines, aerospace and the like.
The high voltage and high current fuse is generally composed of a ceramic tube 1, a packed sand body, a melt and a metal end cap. The ceramic tube is of a hollow structure, is generally formed by an isostatic pressing process, and has the characteristics of high strength and good sealing property; the ceramic tube 1 is filled with sand, melt and other electrical structures. In order to obtain higher breaking speed and longer service life, the fuse generally adopts a pure silver tape as a melt, the melt penetrates through the hollow ceramic tube and is led out from two ends of the ceramic tube 1, sand for arc extinction completely fills the space between the melt and the inner wall of the hollow ceramic tube 1, sand is solidified by adopting a curing agent to form a sand column, and the melt is wrapped in the middle of the sand column. The two ends of the ceramic tube 1 are respectively connected with an inner ceramic tube cap 2, the inner ceramic tube cap 2 is in a two-layer hollow step column shape, the part with smaller inner diameter extends into the ceramic tube 1, and the melts led out from the two ends of the ceramic tube 1 respectively penetrate through the inner ceramic tube cap 2 and then are welded on the inner ceramic tube caps 2 at the two ends of the ceramic tube 1. The outer sides of the ceramic tube inner caps 2 at the two ends of the ceramic tube 1 are respectively connected with a ceramic tube outer cap 3, and one end of the ceramic tube outer cap 3 is attached to the end face of the part with the larger inner diameter of the ceramic tube inner cap 2, so that the fuse is sealed.
Practical application environments of the fuse include damp heat, salt spray corrosion, high and low temperature impact, vibration, vacuum and the like. If the ceramic tube 1 and the metal end cap of the fuse are not sealed and packaged, water vapor in an application environment can easily enter the tube body, so that the solidified sand column is affected with damp and dispersed, and a melt silver belt can be corroded even has silver ion migration problem after being affected with damp; if salt fog exists in the environment, the fused mass in the fuse ceramic tube 1 is also corroded; in a high-temperature and low-temperature environment, once the temperature is reduced to be below zero, frost is formed on the tube wall after the interior of the fuse is damped; even under the vacuum environment, the gas sealed in the fuse can be gradually lost, the sand column pores form low pressure or vacuum due to the loss of the gas, and the breaking arc extinguishing time is prolonged. The non-sealed fuse can not adapt to various severe working conditions in practical application environment, and the use performance is greatly limited. In order to improve the adaptability and stable reliability of the fuse under a severe environment, the fuse is required to be subjected to sealing and packaging treatment. Because the tube wall of the ceramic tube 1 generally has better self-sealing performance, the key parts of sealing are that two end faces of the ceramic tube are connected with the two ceramic tube inner caps 2 and the two ceramic tube inner caps 2 are connected with the two ceramic tube outer caps 3 in a sealing way, and at least four sealing surfaces are involved.
The commonly used sealing and packaging methods at present comprise sealing by a sealing ring, glue pouring, welding, sealing and the like. If four sealing surfaces of the fuse are sealed by the sealing rings, sealing grooves, sealing ring compression joint structures and the like must be designed, which is extremely difficult to realize for the end face of the fuse ceramic tube 1 and the thin-wall metal end cap with small size, even if a corresponding sealing structure can be designed, the size of only the sealing structure part is comparable to the whole size of the fuse, and the leakage rate of sealing ring sealing packaging is large and far less than 1 multiplied by 10-9Pa·m3The sealing method is not suitable for sealing because of the order of/s. The glue filling and sealing are that liquid colloid is filled into 4 sealing surfaces of the fuse, the colloid is filled into a sealing gap and is cooled and solidified to realize sealing, the colloid is easy to deform, tear or age under the influence of environmental temperature, vibration and stretching, internal and external air pressure difference and the like, the mechanical strength, the environmental tolerance and the reliability are poor, and the leakage rate is highTherefore, the glue-filling and sealing method is not suitable for use. In contrast, the welding and sealing method can realize higher mechanical strength, environmental tolerance and stable reliability by welding 4 sealing surfaces of the fuse together, and can control the leakage rate of the fuse to be 1 × 10-9Pa·m3In the order of/s.
Common welding and sealing methods include friction welding, resistance welding, argon arc welding, plasma welding and the like. The friction welding, the resistance welding, the argon arc welding, the plasma welding and other methods can realize the reliable welding between the ceramic 1 and the metal end cap and between the metal end cap by instantly generating high temperature higher than 1000 ℃, but the appearance of the welding seam is not beautiful, under the high welding temperature, the problems of aging, cracks or damages and the like can be caused by the uneven thermal expansion of the fuse ceramic tube 1 and the sand body and the silver belt filled in the fuse ceramic tube, so that the fuse is unusable, the welding methods can only be carried out under the atmospheric environment, the sealing welding is difficult to realize under the specific pure atmosphere or vacuum environment, and the technical requirements of inflation or vacuum sealing and the like can not be realized in the fuse. Therefore, high temperature welding methods such as friction welding, resistance welding, argon arc welding, plasma welding and the like are not suitable for sealing and packaging the fuse.
Disclosure of Invention
The invention mainly aims to solve the technical problems that sealing rings or glue pouring seals are adopted at two ends of a fuse in the prior art, the sealing structure is difficult to design, the sealing effect is poor, and the conventional welding method in welding sealing is adopted, so that the ceramic tube and fillers in the ceramic tube are easy to damage due to the fact that the instantaneous temperature is high during welding, and provides a sealing and packaging method for a high-voltage high-current fuse.
In order to achieve the purpose, the invention provides the following technical scheme:
the method for hermetically packaging the high-voltage high-current fuse is characterized by comprising the following steps of:
s1, processing the end face of the ceramic tube
S1.1, coating a metallization paste on two end faces of a ceramic tube and drying;
s1.2, carrying out primary metallization sintering on the ceramic tube processed in the step 1.1 to form metallization layers on two end faces of the ceramic tube;
s1.3, plating nickel layers on the metalized layers on the two end faces of the ceramic tube;
s1.4, performing secondary metallization sintering on the ceramic tube treated in the step 1.3;
s2, processing the inner cap of the ceramic tube
Electroplating a nickel layer on the surface of the inner cap of the ceramic tube;
s3, vacuum brazing of ceramic tube inner cap
S3.1, welding the inner caps of the ceramic tubes processed in the step S2 to the two ends of the ceramic tubes processed in the step S1.4 in a vacuum brazing mode;
s3.2, performing gold plating treatment on the surface of the inner cap of the ceramic tube;
s4, treating the outer cap of the ceramic tube
Plating a nickel layer on the surface of the outer cap of the ceramic tube, and then plating gold;
s5, brazing the inner cap and the outer cap of the ceramic tube
S5.1, completing electrical structure filling in the ceramic tube;
s5.2, brazing the outer caps of the ceramic tubes outside the inner caps of the ceramic tubes at the two ends of the ceramic tubes to complete the sealing and packaging of the fuse.
Further comprising step S6, leak detection is sealed,
and (4) carrying out sealing leakage detection on the fuse packaged in the step S5.2 by adopting a fluorine oil leakage detection method and a helium mass spectrum leakage detection method, and if the leakage rate is less than or equal to 1 multiplied by 10-9Pa·m3And s, packaging to be qualified; otherwise, degraded processing or scrapped.
Further, step S5-6 is included, wherein the outer surface of the ceramic tube is subjected to sand blasting.
Further, in step S1.1, the metallization paste is made of molybdenum powder and manganese powder.
Further, the step S1.2 is specifically to put the ceramic tube processed in the step 1.1 into a hydrogen furnace, sinter the ceramic tube at 1360-.
Further, the step S1.4 is specifically to place the ceramic tube processed in the step 1.3 into a hydrogen furnace, sinter the ceramic tube at 780-.
Further, in step S3.1, the vacuum brazing is carried out in a vacuum furnace, AgCu28 is used as a solder in the welding process, and the vacuum degree in the vacuum furnace is more than or equal to 5 multiplied by 10-4Pa, heating the vacuum furnace to 400 ℃ at the heating rate of 15-20 ℃/min during welding, preserving heat for 5min, heating the vacuum furnace to 800-.
Further, in step S3.2, cobalt is used as a hardening agent in the gold plating process, and the gold plating purity is greater than or equal to 99.9%; in step S4, the nickel electroplating layer uses a nickel sulfamate bath as an electroplating bath, the gold plating process uses cobalt as a hardening agent, and the gold plating purity is greater than or equal to 99.9%.
Further, in step S1.3, the thickness of the nickel layer of the electroplated nickel layer is 2-5 μm; in step S2, the thickness of the nickel layer of the electroplated nickel layer is 2-8.9 μm; in step S4, the thickness of the nickel layer of the electroplated nickel layer is 2-8.9 μm.
Further, in step S5.2, the brazing is carried out in a brazing furnace, AuSn20 is used as a welding flux during welding, the vacuum degree in the brazing furnace is less than or equal to 2KPa, nitrogen is slowly filled into the brazing furnace during welding until the air pressure in the nitrogen furnace reaches 98-102kPa, the temperature in the brazing furnace is increased to 23 ℃ at the heating rate of 10-15 ℃/min, the temperature is kept for 5min, then the temperature is increased to 360 ℃ at the heating rate of 6-10 ℃/min, the heating is stopped after the temperature is kept for 5-15min, the temperature in the brazing furnace is reduced to below 60 ℃, the vacuum brazing of the ceramic tube outer cap is completed, and the fuse is taken out.
Compared with the prior art, the invention has the beneficial effects that:
1. the invention relates to a sealing packaging method of a high-voltage large-current fuse, which adopts brazing to complete the sealing of an inner ceramic tube cap and an outer ceramic tube cap at two ends of a ceramic tubeCompared with other welding methods, the welding temperature is lower, the welding seam of the fuse can be uniformly sealed, the welding strength is higher, the appearance of the welding seam is attractive, and the internal electrical structure of the fuse is not damaged. In addition, the ceramic tube inner cap and the ceramic tube outer cap are both subjected to special plating treatment, so that the environmental adaptability and reliability of the fuse end cap and the sealing position can be greatly improved, the fuse has the characteristics of high mechanical strength, good environmental tolerance and high structural stability and reliability, and the leakage rate of the sealed fuse is less than or equal to 1 x 10 after verification-9Pa·m3/s。
2. The invention also comprises a leak detection verification step, and after the sealing packaging is completed, whether the product is qualified or not is confirmed through leak detection testing, so that the defective product is prevented from being used.
3. After the encapsulation of the fuse, the sand blasting treatment is carried out on the surface of the ceramic tube, so that the appearance of the fuse is more attractive.
4. The ceramic tube inner cap and the ceramic tube outer cap are brazed in a nitrogen furnace or a vacuum furnace, so that the requirement of filling pure nitrogen with specific air pressure or vacuumizing in the fuse can be conveniently met, and meanwhile, the environmental adaptability and the reliability of the fuse sealing can be greatly improved by adopting special welding flux. The AgCu28 solder sheet is adopted to realize vacuum brazing of the end-face metalized ceramic tube and the ceramic tube inner cap, so that the problem of reliable sealing welding of the ceramic tube inner cap and the ceramic tube is solved; in the step of low-temperature brazing of the ceramic tube inner cap and the ceramic tube outer cap, the brazing sealing of the gold-plated ceramic tube outer cap and the gold-plated ceramic tube inner cap is realized by adopting an AuSn20 solder sheet, the brazing temperature is reduced to 320-360 ℃, and the brazing temperature is ensured not to influence the electrical structures such as sand bodies, melts and the like filled in the fuse. In addition, the nitrogen furnace is firstly vacuumized and then filled with nitrogen, so that the AuSn20 solder sheet can be ensured to be melted and not oxidized in the vacuum or nitrogen protective atmosphere, the problem that the ceramic tube cannot be vacuumized or filled with protective nitrogen after the fuse is sealed in the common welding mode is solved, and the reliability of the fuse is improved.
Drawings
Fig. 1 is a schematic structural diagram of a high-voltage high-current fuse according to the present invention.
Wherein, 1-ceramic tube, 2-ceramic tube inner cap, 3-ceramic tube outer cap.
Detailed Description
The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention and the accompanying drawings, and it is obvious that the described embodiments do not limit the present invention.
(1) And (5) metalizing the end face of the ceramic tube.
Taking the alumina ceramic tube 1 which is formed and turned under the isostatic pressing process and finishes the blank sintering, putting the alumina ceramic tube 1 on a surface grinder to grind and process two end surfaces of the ceramic tube 1, wherein the size of the ceramic tube 1 after the processing is finished is as follows: the length is 121mm, the inner diameter is 14mm, and the outer diameter is 22 mm; placing the ceramic tube 1 on a chamfering machine, performing blunt treatment on right angles at two ends of the ceramic tube 1, placing the ceramic tube 1 in an ultrasonic cleaning machine for ultrasonic cleaning after chamfering, and taking out and drying the ceramic tube 1 after cleaning; and (3) detecting the appearance and the size of the dried ceramic tube 1, wherein the appearance is required to have no defects such as impurities, collision damage, ceramic blisters, pinholes and the like, and the size meets the preset requirement.
Firstly, printing a metallization paste made of metal molybdenum powder and manganese powder on one end face of a ceramic tube 1, drying the metallization paste, then printing the metallization paste on the other end face of the ceramic tube 2, and drying the metallization paste again; putting the ceramic tube 1 with the end face printed with the metallization paste into a hydrogen furnace for primary metallization sintering, completing the primary metallization sintering of 9 ceramic tubes 1at one time, sintering for 30min at 1400 ℃ under 1atm hydrogen-nitrogen mixed atmosphere, stopping heating, naturally cooling to room temperature, and taking out the ceramic tube 1; and (3) detecting the 9 ceramic tubes 1 in the batch, wherein the appearance is required to have no defects such as peeling, bulges and the like, extracting 3 ceramic tubes 1 from the batch, and detecting whether the thicknesses of the metalized layers on the two end faces of each ceramic tube are within the range of 50-100 mu m.
Binding the ceramic tube 1 by using a nickel wire, enabling the nickel wire to be well contacted with a metalized area on the end surface of the ceramic tube 1, and hanging the ceramic tube 1 on an electroplating hanger through the nickel wire; putting the hanger hung with the ceramic tube 1 into an electroplating bath, and plating a nickel layer on the surface of the metalized area on the end face of the ceramic tube 1, wherein the thickness of the plating layer is 2-5 mu m; after the plated nickel on the metalized area of the end face of the ceramic tube 1 is finished, taking out the ceramic tube 1, washing the ceramic tube 1 in a flowing deionized water tank, putting the ceramic tube 1 into boiling deionized water to boil for 10 minutes, taking out the ceramic tube 1 from the boiling water, and wiping the ceramic tube with clean cotton yarn.
And (2) putting the ceramic tube 1 into a hydrogen furnace again for secondary metallization sintering, sintering the ceramic tube 1 again for 1 hour at 820 ℃ in a hydrogen atmosphere of 1atm, cooling and taking out the ceramic tube, then checking the combination condition of the nickel plating layer on the end face of the ceramic tube 1 and the molybdenum-manganese basal layer, and requiring that the nickel plating layer has no defects of peeling, bubbling and the like, and extracting 3 nickel plating layers with the thickness of 2-5 microns on the metallized end face from 9 ceramic tubes 1 in the batch.
(2) Ceramic tube inner cap 2 nickel plating
The ceramic tube inner caps 2 are processed by Tu1 oxygen-free copper, each ceramic tube inner cap 2 is of a thin plate circular ring structure, the outer diameter of each ceramic tube inner cap 2 is 22mm, the inner diameter of each ceramic tube inner cap is 8mm, and the thickness of each ceramic tube inner cap is 2.5 mm; the machined 18 ceramic tubes have inner caps 2, the surface roughness Ra is less than or equal to 1.6 mu m, no visible burrs are generated, and no defects such as holes and pits are generated on the surface;
after the surfaces of 18 ceramic tube inner caps 2 are cleaned, putting the ceramic tube inner caps into an electroplating bath for nickel plating through a hanger, wherein the thickness of each nickel plating layer is within the range of 2.0-8.9 mu m; after the electroplating nickel plating is finished, taking out the ceramic tube inner cap 2, washing the ceramic tube inner cap in a flowing deionized water tank, and then putting the ceramic tube inner cap 2 into boiling deionized water to be boiled for 10 minutes; taking out the inner cap 2 of the ceramic tube from the boiling water, cooling and wiping the inner cap by clean cotton yarn; extracting 5 pieces of the 18 ceramic tube inner caps 2 to carry out thickness test of surface nickel plating layers, wherein the thickness of the nickel plating layers is required to be within the range of 2.0-8.9 mu m; the quality test method of the coating in appendix B of GJB2440A-2006 Universal Specification for hybrid Integrated Circuit Shell is adopted to carry out the quality test of the nickel coating on the randomly extracted 3 ceramic tube inner caps 2, and the nickel coating has no defects of peeling, bubbling and the like after the test;
(3) vacuum brazing between the ceramic tube 1 and the ceramic tube inner cap 2
Selecting solder sheets made of AgCu28 materials as the solder sheets for brazing the metalized end faces at the two ends of the ceramic tube 1 and the inner cap 2 of the nickel-plated ceramic tube in a way of matching with the torus, wherein the AgCu28 solder sheets are of thin plate torus structures, the inner diameter is 15mm, the outer diameter is 22mm, and the thickness is about 100 mu m; cleaning a vacuum furnace tray, a fuse brazing mold and a pressing block, and neatly placing the brazing mold and the pressing block on an assembly platform; the appearances of the ceramic tube 1, the AgCu28 solder sheet and the ceramic tube inner cap 2 are inspected, and no damage defect and pollution are caused.
Taking an inner cap 2 of the ceramic tube as an inner cap at the lower end of the ceramic tube 1, and placing the ceramic tube on a brazing die according to the assembly direction; clamping an AgCu28 solder sheet as a lower AgCu28 solder sheet by using a pair of tweezers, and placing the lower AgCu28 solder sheet at the middle position of the upper annular surface of the lower end inner cap; vertically placing the ceramic tube 1 on the upper annular surface of the lower AgCu28 solder sheet, and enabling the lower end surface metallization layer of the ceramic tube 1 to be just in contact alignment with the upper annular surface of the lower AgCu28 solder sheet; and placing another upper AgCu28 solder sheet in the middle of the surface of the metalized layer on the upper end face of the ceramic tube 1, wherein the lower annular surface of the upper AgCu28 solder sheet is in contact with the surface of the metalized layer on the upper end face of the ceramic tube 1, the upper end of the upper AgCu28 solder sheet is placed with another ceramic tube inner cap 2 as an upper end inner cap, and the upper annular surface of the upper AgCu28 solder sheet is in contact alignment with the bottom surface of the upper end inner cap.
Placing the assembled ceramic tube inner cap 2, the solder sheet and the ceramic tube 1 on a tray of a vacuum furnace as a set of ceramic tubes 1 to be welded; putting 9 sets of ceramic tubes 1 to be welded on a tray of the vacuum furnace, wherein the interval between every two sets of ceramic tubes is 30 mm, checking the assembly structure of the ceramic tubes 1 to be welded, enabling the ceramic tubes 1 to be in good contact with AgCu28 solder sheets and AgCu28 solder sheets and the inner caps 2 of the ceramic tubes, and enabling the ceramic tubes 1 to be vertical and stable; after the detection, 9 pressing blocks are respectively placed on the upper surfaces of the inner caps at the upper ends of the 9 sets of ceramic tubes to be welded 1, the pressing blocks are made of blackening 45# steel, and the weight of the pressing blocks is within the range of 300 +/-15 g.
Closing the door of the vacuum furnace, starting the vacuum pump, vacuumizing the furnace chamber until the vacuum degree reaches 5 multiplied by 10-4After Pa, starting heating in a vacuum furnace, raising the temperature to 400 ℃ at the heating rate of 15 ℃/min, preserving the heat for 5min, raising the temperature to 820 ℃ at the heating rate of 7.5 ℃/min, preserving the heat for 5min, stopping heating in the vacuum furnace, and naturally cooling; when the temperature in the vacuum furnace is reduced to 400 ℃, starting an air cooling fan, and conveying nitrogen into the hearth to rapidly cool the furnace chamber; the temperature in the furnace chamber is reduced to below 60 ℃, the furnace door is opened, and the ceramic tube 1 is taken outWelding the ceramic tube inner cap 2 with the body; the leakage detection is carried out on the welded body of the ceramic tube 1 and the ceramic tube inner cap 2 which are brazed, the leakage rate of two welding seams of the two ends of the ceramic tube 1 and the upper inner cap and the lower inner cap is less than or equal to 1 multiplied by 10-9Pa·m3/s。
(4) Gold plating of welding body of ceramic tube inner cap 2
Carrying out gold plating treatment on the surface of the ceramic tube inner cap 2 of the welded body of the 9 ceramic tubes 1 and the ceramic tube inner cap 2, taking out the welded body after the gold plating is finished, and washing the welded body in a flowing deionized water tank; randomly extracting 2 points from the surface of the inner cap 2 of the ceramic tube at 3-5 points, and testing the thickness of the gold-plated layer to be within the range of 2.5-5 mu m; adopting a GJB2440A-2006 appendix B coating quality test method, sampling 3 welding bodies of 9 gold-plated ceramic tubes 1 and ceramic tube inner caps 2, and carrying out gold-plating layer quality test, wherein the gold-plating layer has no defects of peeling, bubbling and the like; under the irradiation of a 40W fluorescent lamp, the distance is 500mm, the surface color of the gold-plated layer is uniform and consistent by visual observation along the light direction, and the phenomena of blooming, fogging and scratching are avoided;
(5) ceramic tube outer cap 3 nickel plating gold plating
The ceramic tube outer caps 3 are made of Tu1 oxygen-free copper, the bottom of each ceramic tube outer cap 3 is of a circular plate structure, the diameter of each circular plate is 22mm, and the thickness of each circular plate is 3 mm; the roughness Ra of the surface of the outer cap 3 of the ceramic tube after being processed is less than or equal to 1.6 mu m, no visible burr exists, and no defects such as holes, pits and the like exist on the surface;
cleaning the surfaces of 18 ceramic tube outer caps 3, and putting the ceramic tube outer caps into an electroplating bath for nickel plating through a hanger; after the nickel plating is finished, taking out the ceramic tube outer cap 3, washing the ceramic tube outer cap in a flowing deionized water tank, and then putting the ceramic tube outer cap 3 into boiling deionized water to be boiled for 10 minutes; taking out the ceramic tube outer cap 3 from the boiling water, cooling and wiping the ceramic tube outer cap by clean cotton yarn; sampling 3 ceramic tubes from 18 nickel-plated ceramic tube outer caps 3, randomly selecting 3-5 positions on the surface of each sampled ceramic tube outer cap 3, and testing the thickness of a nickel layer, wherein the thickness of the nickel layer is within the range of 2.0-8.9 mu m; performing a nickel plating layer quality test on the sampled 3 ceramic tube outer caps 3 by adopting a GJB2440A-2006 appendix B plating layer quality test method of hybrid integrated circuit shell general Specification, wherein the nickel plating layer has no defects of peeling, bubbling, scratching and the like;
carrying out gold plating treatment on the 18 nickel-plated ceramic tube outer caps 3, taking out the ceramic tube outer caps 3 after the gold plating is finished, and washing the ceramic tube outer caps in a flowing deionized water tank; randomly extracting 3 ceramic tube outer caps 3, detecting 3-5 points on the surface of the ceramic tube outer caps 3, and testing the thickness of a gold-plated layer within the range of 2.5-5 mu m; the gold plating layer quality test method is adopted in the GJB2440A-2006 appendix B coating quality test method of hybrid integrated circuit shell general Specification, gold plating layer quality tests are carried out on 3 sampled ceramic tube outer caps 3, defects such as peeling and bubbling do not occur in the gold plating layer, the distance is 500mm under the irradiation of a 40W fluorescent lamp, the surface color of the gold plating layer is uniform and consistent through visual observation along the light direction, and the phenomena of blooming, fogging and scratching are avoided.
(6) The ceramic tube inner cap 2 and the ceramic tube outer cap 3 are brazed at low temperature
Before low-temperature brazing between the ceramic tube inner cap 2 and the ceramic tube outer cap 3, completing the filling of an electrical structure in the DC1600V30A fuse ceramic tube 1; cleaning a tray of a nitrogen treatment furnace; taking out the brazing die and the pressing block of the fuse, wiping the die and the pressing block clean, and placing the die and the pressing block on an assembly platform in order; the method is characterized in that a solder sheet made of AuSn20 material is used as a brazing solder sheet of the matching circular ring surface of the ceramic tube inner cap 2 and the ceramic tube outer cap 3, the AuSn20 solder sheet is of a thin-plate circular ring structure, the inner diameter is 15mm, the outer diameter is 22mm, and the thickness is 100 micrometers; checking that the ceramic tube inner cap 2 and the ceramic tube 1 form a welding body, an AuSn20 welding sheet and a ceramic tube outer cap 3, and avoiding damage and pollution;
taking an outer cap 3 of the ceramic tube as a lower outer cap, and inversely placing the lower outer cap on a brazing die according to the assembly direction; clamping an AuSn20 solder sheet as a lower solder sheet by using tweezers, and placing the lower solder sheet on the bottom surface of the disc at the upper end of the lower outer cap; vertically placing a welding body of the ceramic tube inner cap 2 and the ceramic tube 1 in the middle of the upper surface of the lower welding flux sheet; clamping another AuSn20 solder sheet as an upper solder sheet by using a pair of tweezers, and placing the upper solder sheet at the middle position of the top of the welding body of the cap 2 in the ceramic tube; taking the other gold-plated outer cap as an upper outer cap, and placing the other gold-plated outer cap in the middle of the upper surface of the upper welding sheet according to the assembly direction; the assembled upper outer cap, lower outer cap, upper solder sheet, lower solder sheet and ceramic tube inner cap welding body are used as a set of samples to be welded; after 9 sets of samples to be welded are filled, putting the 9 sets of samples to be welded on a tray of a nitrogen furnace together, enabling the interval between a ceramic tube 1 and the ceramic tube 1 to be 30 mm, checking that the ceramic tube outer cap 3, the AuSn20 soldering lug and the inner cap in each set of samples to be welded are in good contact, and enabling the ceramic tube to be vertical and stable; 9 pressing blocks are respectively arranged on the top parts of the outer caps of the 9 sets of samples to be welded, the material of each pressing block is blackening-treated 45# steel, and the weight of each pressing block meets 300 +/-15 g;
closing a nitrogen furnace door, starting a vacuum pump, vacuumizing the cavity of the nitrogen furnace, opening a nitrogen valve after the vacuum degree reaches 2kPa, slowly filling nitrogen into the nitrogen furnace, and opening an emptying valve when the air pressure in the cavity of the nitrogen furnace reaches 100 kPa; after the air pressure in the nitrogen furnace cavity is stabilized, starting a heating button, raising the temperature in the furnace cavity to 230 ℃ at the heating rate of 10 ℃/min, preserving the heat for 5min, then raising the temperature to 350 ℃ at the heating rate of 7.5 ℃/min, preserving the heat for 10 min, stopping heating, and naturally cooling in the nitrogen furnace cavity; when the temperature is reduced to below 60 ℃, opening a nitrogen furnace door, and taking out the fuse;
(7) and (6) sand blasting.
Wrapping the metal end caps at the two ends of the fuse by using paper and adhesive tape, and only exposing the ceramic tube 1 in the middle; sand blasting is carried out on the surface of the fuse ceramic tube by a sand blasting machine, the sand blasting pressure is 0.3MPa, and the sand body is 80# white corundum sand; stopping sand blasting after the surface of the ceramic tube 1 becomes white, taking out the fuse, and detaching the protective paper and the adhesive tape wrapped at the two ends to make the surface of the fuse more beautiful.
(8) And (5) sealing and detecting leakage.
According to the GJB360B method 112, adopting fluorine oil leakage detection and helium mass spectrum leakage detection methods to perform sealed leakage detection screening on 9 sealed fuses, wherein the leakage rate is lower than 1 × 10-9Pa·m3/s。
The fuse packaged by the method tests the static resistance of the fuse, and the test value is not increased compared with the value before sealing and packaging, so that the method has no influence on the static resistance value of the fuse; the rated current-carrying life of the fuse packaged by the invention is tested under the same condition and is basically equivalent to the designed rated current-carrying life, and the test result proves that: the sealing packaging method of the invention has no influence on the key electrical structure and function in the fuse.
In other embodiments of the present invention, when the two ends of the ceramic tube 1 are metallized and sintered once, the ceramic tube is sintered for 60min at 1365 ℃ under 1atm of hydrogen-nitrogen mixed atmosphere, or sintered for 45min at 1430 ℃ under 1atm of hydrogen-nitrogen mixed atmosphere; the temperatures of the secondary metallization sintering of the corresponding ceramic tubes 1 are 780 ℃ and 800 ℃.
In addition, the furnace body used for the above brazing is defined as a nitrogen furnace if the furnace body is filled with nitrogen gas for brazing, and as a vacuum furnace if the furnace body is evacuated for brazing.
The above description is only an embodiment of the present invention, and is not intended to limit the scope of the present invention, and all equivalent structural changes made by using the contents of the present specification and the drawings, or applied directly or indirectly to other related technical fields, are included in the scope of the present invention.
Claims (10)
1. A method for hermetically packaging a high-voltage high-current fuse is characterized by comprising the following steps:
s1, processing the end face of the ceramic tube (1)
S1.1, coating a metalized paste on two end faces of a ceramic tube (1) and drying;
s1.2, carrying out primary metallization sintering on the ceramic tube (1) processed in the step 1.1, and forming metallization layers on two end faces of the ceramic tube (1);
s1.3, plating nickel layers on the metalized layers on the two end faces of the ceramic tube (1);
s1.4, carrying out secondary metallization sintering on the ceramic tube (1) treated in the step 1.3;
s2, processing the ceramic tube inner cap (2)
Plating a nickel layer on the surface of the inner cap (2) of the ceramic tube;
s3, vacuum brazing of ceramic tube inner cap (2)
S3.1, welding the ceramic tube inner caps (2) processed in the step S2 to the two ends of the ceramic tube (1) processed in the step S1.4 in a vacuum brazing mode;
s3.2, performing gold plating treatment on the surface of the ceramic tube inner cap (2);
s4, processing the outer cap (3) of the ceramic tube
Plating a nickel layer on the surface of the outer cap (3) of the ceramic tube, and then plating gold;
s5, brazing the ceramic tube inner cap (2) and the ceramic tube outer cap (3)
S5.1, completing the filling of an electrical structure in the ceramic tube (1);
s5.2, brazing the outer ceramic tube caps (3) outside the inner ceramic tube caps (2) at the two ends of the ceramic tube (1) to complete the sealing and packaging of the fuse.
2. A high voltage high current fuse hermetic package method according to claim 1, wherein: and also includes step S6, leak sealing,
and (4) carrying out sealing leakage detection on the fuse packaged in the step S5.2 by adopting a fluorine oil leakage detection method and a helium mass spectrum leakage detection method, and if the leakage rate is less than or equal to 1 multiplied by 10-9Pa·m3And s, packaging to be qualified; otherwise, degraded processing or scrapped.
3. A high voltage high current fuse hermetic package method according to claim 2, wherein: further comprises a step S5-6 of performing sand blasting treatment on the outer surface of the ceramic tube (1).
4. A high voltage high current fuse hermetic package method according to claim 1, 2 or 3, wherein: in step S1.1, the metallization paste is made of molybdenum powder and manganese powder.
5. A high voltage high current fuse hermetic package method according to claim 4, wherein: and S1.2, specifically, placing the ceramic tube (1) treated in the step 1.1 into a hydrogen furnace, sintering for 25-60min at 1360-1430 ℃ under 1atm of hydrogen-nitrogen mixed atmosphere, stopping heating, cooling to room temperature, taking out, and forming metalized layers on two end faces of the ceramic tube (1).
6. A high voltage high current fuse hermetic package method according to claim 5, wherein: the step S1.4 is specifically that the ceramic tube (1) treated in the step 1.3 is placed into a hydrogen furnace, sintered for 60min at 780-820 ℃ under 1atm hydrogen atmosphere, cooled and taken out.
7. A high voltage high current fuse hermetic package method according to claim 6, wherein: in step S3.1, the vacuum brazing is carried out in a vacuum furnace, AgCu28 is used as a solder during welding, and the reading of the vacuum degree in the vacuum furnace is less than or equal to 5 multiplied by 10-4Pa, heating the vacuum furnace to 400 ℃ at the heating rate of 15-20 ℃/min during welding, preserving the heat for 5min, heating the vacuum furnace to 800-.
8. A high voltage high current fuse hermetic package method according to claim 7, wherein: in the step S3.2, cobalt is adopted as a hardening agent in the gold plating treatment, and the gold plating purity is more than or equal to 99.9%; in step S4, the nickel electroplating layer uses a nickel sulfamate bath as an electroplating bath, the gold plating process uses cobalt as a hardening agent, and the gold plating purity is greater than or equal to 99.9%.
9. A high voltage high current fuse hermetic package method according to claim 8, wherein: in the step S1.3, the thickness of the nickel layer of the electroplated nickel layer is 2-5 μm; in step S2, the thickness of the nickel layer of the electroplated nickel layer is 2-8.9 μm; in step S4, the thickness of the nickel layer of the electroplated nickel layer is 2-8.9 μm.
10. A high voltage high current fuse hermetic package method according to claim 9, wherein: and S5.2, performing brazing in a brazing furnace, wherein AuSn20 is used as a solder during welding, the vacuum degree in the brazing furnace is less than or equal to 2KPa, nitrogen is slowly filled into the brazing furnace during welding until the air pressure in the nitrogen furnace reaches 98-102kPa, the temperature in the furnace is increased to 23 ℃ at the heating rate of 10-15 ℃/min, the temperature is kept for 5min, the temperature is increased to 360 ℃ at the heating rate of 6-10 ℃/min, the heating is stopped after the temperature is kept for 5-15min, the temperature in the brazing furnace is reduced to below 60 ℃, the vacuum brazing of the ceramic tube outer cap (3) is completed, and the fuse is taken out.
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