Metal-ceramic composite cover plate for controlling hydrogen content in airtight packaging shell and manufacturing method of metal-ceramic composite cover plate
By attaching hydrogen-absorbing material to the metal-ceramic composite cover plate of aerospace-grade RF microwave power transistors and designing the metallization pattern of alumina HTCC ceramic sheets, the hydrogen control problem was solved, compatibility with hermetically sealed packaging and electromagnetic unshielding was achieved, manufacturing costs were reduced, and device reliability was improved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- NANJING SOLID DEVICE FACTORY
- Filing Date
- 2025-12-18
- Publication Date
- 2026-04-10
AI Technical Summary
In the hermetically sealed packaging process of aerospace-grade radio frequency microwave power transistors, hydrogen is difficult to control effectively, leading to device performance drift and failure. Existing technologies cannot reduce costs while meeting various design requirements.
By adopting a metal-ceramic composite cover plate structure, hydrogen-absorbing material is attached to the cover plate, and a metallized pattern of alumina HTCC ceramic sheet is designed to maximize the hermetic sealing and electromagnetic unshielded area, while simplifying the processing technology and reducing manufacturing costs.
This approach simplifies the high-temperature baking process for hydrogen removal while meeting hydrogen control requirements, reduces manufacturing costs, and improves device reliability and performance stability.
Smart Images
Figure CN121843574A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of hermetic packaging of radio frequency microwave power transistors, and particularly relates to a metal-ceramic composite cover plate for controlling hydrogen content in a hermetic packaging shell and a manufacturing method thereof. BACKGROUND
[0002] Astronaut-grade radio frequency microwave power transistors are usually hermetically packaged to isolate external water vapor and harmful gases, but hydrogen gas remaining in the packaging process or in the use material may still enter the device cavity. Hydrogen gas may cause device performance drift, increased leakage current, and even failure under certain conditions, so controlling hydrogen content is a key link to improve device reliability.
[0003] Hydrogen mainly comes from the following aspects: (1) packaging materials, such as adsorbed or dissolved hydrogen in metal plating; (2) gases released during the packaging process; (3) gases remaining during the welding process of the tube shell and the cover plate; (4) hydrogen gas slowly released after packaging. Correspondingly, the measures for controlling hydrogen content include but are not limited to: (1) reducing the initial hydrogen content of hydrogen source materials, and preferentially selecting metal materials that have been vacuum annealed; (2) baking before packaging is an effective means to remove hydrogen gas. Studies have shown that using high-temperature vacuum pre-baking can significantly reduce the adsorbed water vapor and hydrogen content in the packaging material. This method promotes the escape of hydrogen gas from the material by heating the device in a vacuum environment, thereby reducing the hydrogen concentration in the internal cavity after packaging; (3) introducing hydrogen-absorbing materials (such as titanium-based and zirconium-aluminum alloys) into the packaging cavity can fix hydrogen gas through physical adsorption or chemical reaction, reducing its free concentration. Among the above-mentioned hydrogen control measures, the third measure is the most cost-effective way.
[0004] One of the design challenges of astronaut-grade radio frequency microwave power transistors is to meet multiple design index requirements, such as packaging hermeticity, internal hydrogen content, electromagnetic field and microwave characteristics, process compatibility, and control of product manufacturing cost, etc. Therefore, parallel design must be considered to meet the above multiple target requirements to obtain the best overall solution. SUMMARY
[0005] In view of the above-mentioned multi-objective optimization design challenge, the application provides a metal-ceramic composite cover plate for controlling hydrogen content in a hermetic packaging shell and a manufacturing method thereof. First, a hydrogen control scheme of attaching a hydrogen-absorbing material to the cover plate is adopted; second, the design of the metalized pattern of the alumina HTCC ceramic sheet of the cover plate meets the process compatibility requirements of the hydrogen-absorbing sheet; third, the metalized pattern of the ceramic sheet not only meets the requirements of the cover plate hermetic packaging and maximizes the electromagnetic non-shielding area, but also simplifies the overall plating process and reduces the cost of the cover plate green ceramic processing.
[0006] Technical solution: In the first aspect, the application provides a metal-ceramic composite cover plate for controlling hydrogen content in a gas-tight packaging shell, which comprises, from bottom to top, a metal sealing ring P1, an alumina HTCC ceramic sheet P2 and a metal hydrogen-absorbing sheet P3, wherein the metal sealing ring P1 and the alumina HTCC ceramic sheet P2 are connected by silver-copper solder; the edge thickness of the metal sealing ring P1 is 0.05-0.15 mm to adapt to parallel seam welding process; the metal hydrogen-absorbing sheet P3 is connected to the alumina HTCC ceramic sheet P2 by gold-tin solder or conductive glue; a metallized pattern required for attaching the metal hydrogen-absorbing sheet P3 is made on the surface of the alumina HTCC ceramic sheet P2, and the metallized pattern meets the requirements of gas-tight packaging and maximization of electromagnetic non-shielding area of the cover plate, that is, the shape size of the hydrogen-absorbing sheet required to reach the hydrogen control index is calculated according to the volume of the inner cavity of the shell, and then the metallized pattern of the ceramic sheet is designed according to the shape size of the hydrogen-absorbing sheet.
[0007] Preferably, the metallized patterns made on the front and back surfaces of the alumina HTCC ceramic sheet P2 are electrically connected through metallized vias or metallized hanging holes at four corners.
[0008] Further, the metallized patterns on the front and back surfaces of the alumina HTCC ceramic sheet P2 are completely the same.
[0009] Preferably, the metal hydrogen-absorbing sheet P3 is single-sided gold-plated and connected to the alumina HTCC ceramic sheet P2 by gold-tin solder.
[0010] Preferably, the metal hydrogen-absorbing sheet P3 is not gold-plated and connected to the alumina HTCC ceramic sheet P2 by conductive glue.
[0011] Further, the conductive glue is H20E conductive glue.
[0012] In the second aspect, the application provides a manufacturing method of the cover plate described in the first aspect, comprising the following steps: (1) Preparation of the metal sealing ring P1: using iron-nickel alloy 4J42 or iron-nickel-cobalt alloy 4J29 as raw material, the metal sealing ring P1 is prepared by mechanical stamping or chemical etching method, and is cleaned and annealed before use; (2) Preparation of the alumina HTCC ceramic sheet P2: using alumina as raw material and tungsten as metallized material, the alumina HTCC ceramic sheet P2 is prepared by high-temperature co-firing ceramic process, and is chemically plated with nickel before use; (3) Metal hydrogen-absorbing sheet P3: according to the volume of the inner cavity, the titanium-based alloy or zirconium-aluminum alloy hydrogen-absorbing sheet P3 is designed, which is not gold-plated or single-sided gold-plated; (4) Rack brazing: graphite mold is used to assemble metal sealing ring P1 and alumina HTCC ceramic sheet P2 together in the order from bottom to top, and silver copper brazing filler is placed at the interface position of the connected parts; the assembled graphite mold is placed into a high temperature brazing furnace to be brazed into one, thereby obtaining the cover plate semi-finished product; (5) Electroplating: the cover plate semi-finished product is plated with a nickel layer and a gold layer on the metal surface by using a conventional tube shell electroplating method, thereby obtaining the gold-plated cover plate semi-finished product; (6) Mounting of the metal hydrogen-absorbing sheet P3: for the single-sided gold-plated metal hydrogen-absorbing sheet P3, gold tin solder is used to connect the alumina HTCC ceramic sheet P2; for the non-gold-plated metal hydrogen-absorbing sheet P3, conductive glue is used to connect the alumina HTCC ceramic sheet P2, thereby obtaining the gold-plated cover plate finished product.
[0013] Preferably, the thickness of the ceramic sheet P2 in step (2) is 0.4mm-0.8mm.
[0014] Preferably, the length x width x thickness of the metal hydrogen-absorbing sheet P3 in step (3) is 1mm x 1mm x 0.25mm.
[0015] Preferably, the thickness of the silver copper brazing filler in step (4) is 0.05mm-0.15mm.
[0016] Preferably, the thickness of the nickel layer in step (5) is 1.3um-8.9um, and the thickness of the gold layer is 1.3um-5.7um.
[0017] Beneficial effects: the cover plate is mounted with the hydrogen-absorbing material, so that the conventional tube shell high-temperature baking hydrogen removal process can be simplified or even eliminated, the internal hydrogen content index required by the relevant standards can be met, the alumina HTCC ceramic sheet of the cover plate is reasonably designed, the requirements of the cover plate airtight packaging and the maximum electromagnetic non-shielding area are met, the cover plate ceramic processing and the overall plating process are simplified, the overall manufacturing cost of the tube shell can be greatly reduced while meeting the hydrogen control requirements. BRIEF DESCRIPTION OF DRAWINGS
[0018] Figure 1 is a structural schematic diagram of the metal sealing ring P1; Figure 2 is a structural schematic diagram of the alumina HTCC ceramic sheet P2; Figure 3 is a structural schematic diagram of the hydrogen-absorbing sheet P3; Figure 4 is a structural schematic diagram of the gold-plated cover plate semi-finished product in an embodiment of the present application; Figure 5 is a structural schematic diagram of the gold-plated cover plate finished product in an embodiment of the present application. DETAILED DESCRIPTION
[0019] The present invention will now be described in detail with reference to specific embodiments: The abbreviations represent the following meanings: Len is long in shape; Wid has a wide profile; LCav has a long lumen. WCav inner cavity width; T represents thickness; Specifically, Len_P1 represents the length of P1's outer shape, Wid_P1 represents the width of P1's outer shape, LCav_P1 represents the length of P1's inner cavity, WCav_P1 represents the width of P1's inner cavity, and T_P1 represents the thickness of P1. Len_P2 represents the length of P2's outer shape, Wid_P2 represents the width of P2's outer shape, LCav_P2 represents the length of P2's metallized inner cavity, WCav_P2 represents the width of P2's metallized inner cavity, and T_P2 represents the thickness of P2. Len_P3 represents the length of P3, Wid_P3 represents the width of P3, and T_P3 represents the thickness of P3. Example 1
[0020] A method for manufacturing a metal-ceramic composite cover plate with controllable internal hydrogen content that is compatible with the mounting dimensions of the industry-standard NI-1230 RF power transistor housing includes the following steps: (1) Preparation of metal sealing ring P1: as follows Figure 1 As shown, a metal sealing ring P1 is made from iron-nickel alloy 4J42 by mechanical stamping or chemical etching. After cleaning and annealing, it is ready for use. Its external dimensions are Len_P1×Wid_P1=30.89mm×8.45mm, the internal cavity dimensions are LCav_P1×WCav_P1=27.04mm×5.16mm, the total thickness of the cover plate is T_P1=0.25mm, and the thickness of the edge area of the cover plate is 0.10mm.
[0021] (2) Preparation of alumina HTCC ceramic sheet P2: such as Figure 2 As shown, an alumina HTCC ceramic sheet P2 is prepared using alumina as the raw material and tungsten as the metallizing material via a high-temperature co-fired ceramic (HTCC) process. After electroless nickel plating, it is ready for use. Its external dimensions are: Len_P2×Wid_P2=28.04mm×6.16mm, the metallized inner cavity dimensions are LCav_P2×WCav_P2=25.74mm×4.86mm, and the ceramic sheet thickness T_P2=0.60mm. The front and back sides of the alumina HTCC ceramic sheet P2 are made with identical metallized patterns, which are connected by metallized through-holes or metallized hanging holes at the four corners to simplify printing and electroplating processes and control costs.
[0022] (3) Metal hydrogen-absorbing sheet P3: titanium alloy material custom-made by an external manufacturer, as shown in the figure, with an outer dimension of Len_P3 x Wid_P3 x T_P3 = 1 mm x 1 mm x 0.25 mm; no gold plating on the surface. Figure 3
[0023] (4) Rack brazing: using a graphite mold, metal sealing ring P1 and alumina HTCC ceramic sheet P2 are assembled together in the order from bottom to top, and 0.05 mm to 0.10 mm thick annular silver-copper brazing material is placed at the interface position of the parts connection; the assembled graphite mold is placed in a high-temperature brazing furnace to be brazed into one, and a cover plate semi-finished product is obtained.
[0024] (5) Electroplating: after the above steps, the metallized area of the ceramic sheet on the cover plate and the metal sealing ring P1 remain connected, and the cover plate semi-finished product can be plated with a nickel layer and a gold layer on the metal surface using conventional tube-shell electroplating methods, with a Ni thickness of 1.3 μm to 8.9 μm and an Au thickness of 1.3 μm to 5.7 μm, to obtain a gold-plated cover plate semi-finished product.
[0025] (6) Metal hydrogen-absorbing sheet P3 mounting: using H20E conductive glue to connect with the alumina HTCC ceramic sheet P2, a gold-plated cover plate finished product is obtained. Example 2
[0026] A metal-ceramic composite cover plate manufacturing method compatible with the installation size of the NI-1230 type RF power tube shell in the industry, which can control the internal hydrogen content, comprises the following steps: (1) Preparation of metal sealing ring P1: using iron-nickel alloy 4J42 as raw material, metal sealing ring P1 is prepared by mechanical punching or chemical etching method, and is cleaned and annealed before use; the outer dimension is Len_P1 x Wid_P1 = 30.89 mm x 8.45 mm, the inner cavity dimension is LCav_P1 x WCav_P1 = 27.04 mm x 5.16 mm, the total thickness of the cover plate is T_P1 = 0.25 mm, and the edge region thickness of the cover plate is 0.10 mm.
[0027] (2) Preparation of alumina HTCC ceramic sheet P2: using alumina as raw material and tungsten as metallization material, alumina HTCC ceramic sheet P2 is prepared by high-temperature co-fired ceramic (HTCC) process, and is chemically plated with nickel before use; the outer dimension is Len_P2 x Wid_P2 = 28.04 mm x 6.16 mm, the metallized inner cavity dimension is LCav_P2 x WCav_P2 = 25.74 mm x 4.86 mm, and the thickness of the ceramic sheet is T_P2 = 0.60 mm. The front and back of the alumina HTCC ceramic sheet P2 are made of the same metallized pattern, and the front and back metallized patterns are connected through metallized vias or metallized hanging holes at the four corners to simplify the printing and electroplating process and control the cost.
[0028] (3) Metal hydrogen-absorbing sheet P3: titanium alloy material customized by an external manufacturer, with an outer dimension of Len_P3 x Wid_P3 x T_P3 = 1 mm x 1 mm x 0.25 mm; single-side gold plating.
[0029] (4) Rack brazing: metal sealing ring P1 and alumina HTCC ceramic sheet P2 are assembled together in the order from bottom to top by using a graphite mold, and a corresponding 0.05 mm to 0.10 mm annular silver-copper brazing material is placed at the interface position of the parts connection; the assembled graphite mold is placed into a high-temperature brazing furnace to be brazed into one body, thereby obtaining a cover plate semi-finished product.
[0030] (5) Electroplating: after the above steps, the metallized area of the ceramic sheet on the cover plate and the metal sealing ring P1 remain connected, and the cover plate semi-finished product can be plated with a nickel layer and a gold layer on the metal surface by using a conventional tube-shell electroplating method, with a Ni thickness of 1.3 μm to 8.9 μm and an Au thickness of 1.3 μm to 5.7 μm, thereby obtaining a gold-plated cover plate semi-finished product, as shown in FIG. 5. Figure 4
[0031] (6) Metal hydrogen-absorbing sheet P3 mounting: gold-tin solder is used to connect the alumina HTCC ceramic sheet P2, thereby obtaining a gold-plated cover plate finished product, as shown in FIG. 6. Figure 5
[0032] The above only describes preferred embodiments of the present application and is not intended to limit the present application, and any modification, equivalent replacement, and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims
1. A metal-ceramic composite cover plate for controlling the hydrogen content inside a hermetically sealed enclosure, comprising, from bottom to top, a metal sealing ring P1, an alumina HTCC ceramic sheet P2, and a metal hydrogen-absorbing sheet P3, wherein the metal sealing ring P1 and the alumina HTCC ceramic sheet P2 are connected by silver-copper solder; the edge thickness of the metal sealing ring P1 is 0.05–0.15 mm to suit parallel seam welding; the metal hydrogen-absorbing sheet P3 is connected to the alumina HTCC ceramic sheet P2 by gold-tin solder or conductive adhesive, characterized in that… Metallization patterns were fabricated on the surface of the alumina HTCC ceramic sheet P2 to accommodate the metal hydrogen absorber P3. The metallization patterns simultaneously met the requirements of the cover's hermetic sealing and the maximization of the electromagnetic unshielded area. Specifically, the required dimensions of the hydrogen absorber to achieve the hydrogen control target were first calculated based on the volume of the inner cavity of the outer shell, and then the metallization patterns of the ceramic parts were designed based on the dimensions of the hydrogen absorber.
2. The metal-ceramic composite cover plate for controlling the hydrogen content inside a hermetically sealed enclosure according to claim 1, characterized in that: The metallized patterns on the front and back of the alumina HTCC ceramic sheet P2 are electrically connected through metallized through-holes or metallized hanging holes at the four corners.
3. The metal-ceramic composite cover plate for controlling the hydrogen content inside a hermetically sealed enclosure according to claim 2, characterized in that: The metallization patterns on the front and back of the alumina HTCC ceramic sheet P2 are exactly the same.
4. The metal-ceramic composite cover plate for controlling the hydrogen content inside a hermetically sealed enclosure according to claim 1, characterized in that: The metal hydrogen-absorbing sheet P3 is gold-plated on one side and is connected to the alumina HTCC ceramic sheet P2 by gold-tin solder.
5. A metal-ceramic composite cover plate for controlling the hydrogen content inside a hermetically sealed enclosure according to claim 1, characterized in that: The metal hydrogen-absorbing sheet P3 is not gold-plated and is connected to the alumina HTCC ceramic sheet P2 via conductive adhesive.
6. A method for manufacturing a metal-ceramic composite cover plate for controlling the hydrogen content inside a hermetically sealed enclosure as described in claim 1, characterized in that, Includes the following steps: (1) Preparation of metal sealing ring P1: Using iron-nickel alloy 4J42 or iron-nickel-cobalt alloy 4J29 as raw materials, metal sealing ring P1 is prepared by mechanical stamping or chemical etching, and then cleaned and annealed for use. (2) Preparation of alumina HTCC ceramic sheet P2: Alumina HTCC ceramic sheet P2 was prepared by using alumina as raw material and tungsten as metallizing material and high temperature co-fired ceramic process. After chemical nickel plating, it was ready for use. (3) Metal hydrogen absorber P3: The hydrogen absorber P3 is made of titanium-based alloy or zirconium-aluminum alloy according to the inner cavity volume. Its surface is not gold-plated or is gold-plated on one side. (4) Brazing: Using a graphite mold, the metal sealing ring P1 and the alumina HTCC ceramic sheet P2 are assembled together in a bottom-up order. The corresponding silver-copper brazing material is placed at the interface of the parts connection. The assembled graphite mold is placed in a high-temperature brazing furnace and brazed into one piece to obtain the cover plate semi-finished product. (5) Electroplating: The cover plate semi-finished product is plated with nickel and gold layers on the metal surface using conventional tube shell electroplating methods to obtain gold-plated cover plate semi-finished product; (6) Mounting of the metal hydrogen absorber P3: For the single-sided gold-plated metal hydrogen absorber P3, gold-tin solder is used to connect it to the alumina HTCC ceramic sheet P2; for the non-gold-plated metal hydrogen absorber P3, conductive adhesive is used to connect it to the alumina HTCC ceramic sheet P2 to obtain the finished gold-plated cover plate.
7. The manufacturing method according to claim 6, characterized in that: In step (2), the thickness of ceramic sheet P2 is 0.4mm to 0.8mm.
8. The manufacturing method according to claim 6, characterized in that: In step (3), the size of the metal hydrogen absorber P3 is 1mm×1mm×0.25mm.
9. The manufacturing method according to claim 6, characterized in that: In step (4), the thickness of the silver-copper brazing filler is 0.05mm to 0.15mm.
10. The manufacturing method according to claim 6, characterized in that: In step (5), the thickness of the nickel layer is 1.3 μm to 8.9 μm, and the thickness of the gold layer is 1.3 μm to 5.7 μm.