A multi-substrate stacking structure for a radiation-resistant point-of-load power supply and an assembly method thereof

Abstract

The present invention discloses a multi-substrate stacking structure for a radiation-resistant point-of-load power supply and an assembly method thereof. The stacking structure includes a tube shell, an AMB ceramic substrate, a power chipset, a control chipset, and an Al2O3 thick-film multilayer ceramic substrate. The AMB ceramic substrate is welded to the tube shell, the Al2O3 thick-film multilayer ceramic substrate is bonded to the AMB ceramic substrate, the AMB ceramic substrate and the Al2O3 thick-film multilayer ceramic substrate are interconnected by wire bonding, the power chipset is mounted on the AMB ceramic substrate, the control chipset is mounted on the Al2O3 thick-film multilayer ceramic substrate, and the cover plate and tube shell are welded using parallel seam welding. The multi-substrate stacking structure improves the assembly density of the radiation-resistant point-of-load power supply under high load current conditions, reduces the conduction band impedance and substrate thermal resistance, and improves the power density and conversion efficiency of the point-of-load power supply.

Description

Technical Field

[0001] The invention belongs to the technical field of power supplies and relates to a multi-substrate stacking structure of a radiation-resistant point-of-load power supply and an assembling method thereof. Background Art

[0002] With the implementation of aerospace projects such as space stations, deep space exploration, and long-life satellites, point-of-load power supplies (POLs) in satellite power systems are increasingly required to be highly reliable, efficient, low-power, compact, and resistant to extremely low-dose-rate radiation. With the continuous advancement of ultra-large-scale integrated circuits (VLSIs) such as CPUs, increasingly complex circuit boards are required to provide a wider range of voltages, lower output voltages, and higher load currents for various DSPs, FPGAs, ASICs, and microprocessors. Hybrid integrated POLs with radiation-resistant designs offer low-voltage, high-current outputs and utilize traditional thick-film processes. This results in high conduction band impedance, high module heat dissipation, and low conversion efficiency, making them inadequate for the high-load current requirements of aerospace electronics systems.

[0003] The existing load point power supply adopts the traditional thick film hybrid integration process. The load point power supply is a hybrid integrated power circuit. A hybrid circuit is a chip device that combines various functions, such as planar inductors, chips, capacitors, etc. Figure 4 and Figure 5 The figure shows a cross-sectional view of a thick-film multilayer substrate structure and a schematic diagram of its assembly process in the prior art. Electrical interconnects are made on an insulating ceramic substrate with a pre-patterned conductor pattern or a combination of conductor and resistor patterns. The insulating ceramic substrate has three main functions: mechanical support for component assembly, a base for electrical interconnect patterns, a substrate for mass-producing thin-film resistors, and a heat dissipation medium for the components. The insulating ceramic substrate is typically made of 96% alumina, though beryllium oxide and aluminum nitride are also used. The functional material for printing the conductor pattern is a high-conductivity metal paste, such as gold, platinum, palladium, silver, or a combination of these metals. The thickness of the conductor paste is 8 to 12 μm. The sheet resistance of Au paste is 10 mΩ / □, and that of AgPb paste is 15 mΩ / □. (□ is the ratio of the conduction band length to width.) A thinner conduction band has a higher sheet resistance. The conduction band loss of 10 A for palladium-silver conduction bands is 10*10*15 mΩ = 1.5 W / □, resulting in low conversion efficiency. The power devices used in the point-of-load power supply are soldered on the AgPb conductor strip using a reflow soldering process. Due to the consideration of soldering reliability, the AgPb conductor strip used for soldering devices can only be printed on the substrate. The soldering reliability of the AgPb conductor strip printed on the high dielectric constant is low, and it is not suitable for aerospace radiation-resistant point-of-load power supplies with high reliability requirements. This reduces the assembly density of the device. Summary of the Invention

[0004] The purpose of the present invention is to solve the problem in the prior art that the conduction band loss of the load point power supply is large, the conversion efficiency is low, and it cannot meet the large load current requirements of the aerospace electronic system, and to provide a multi-substrate stacking structure and an assembly method for a radiation-resistant load point power supply.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A multi-substrate stacking structure of a radiation-resistant point-of-load power supply includes a tube shell, an AMB ceramic substrate, a power chipset, a control chipset, and an Al2O3 thick-film multilayer ceramic substrate;

[0007] The AMB ceramic substrate is welded on the tube shell, the Al2O3 thick film multilayer ceramic substrate is bonded to the AMB ceramic substrate, the AMB ceramic substrate and the Al2O3 thick film multilayer ceramic substrate are interconnected by metal wire bonding, the power chipset is mounted on the AMB ceramic substrate, the control chipset is mounted on the Al2O3 thick film multilayer ceramic substrate, and the cover plate and the tube shell are welded by parallel seam welding.

[0008] A further improvement of the present invention is:

[0009] The power chipset includes an inductor, a power chip, a ceramic capacitor and a tantalum capacitor. The components in the power chipset are mounted on an AMB ceramic substrate through solder paste.

[0010] The control chipset comprises a control chip, a chip capacitor, a thick film resistor block and a thin film resistor network. The components in the control chipset are mounted on an Al2O3 thick film multilayer ceramic substrate through an adhesive.

[0011] A silver-copper bracket is welded on the AMB ceramic substrate, and the silver-copper bracket is led out from the tube shell through a lead wire.

[0012] The lead wire passes through the tube shell through a glass insulator, and the glass insulator is used for electrical isolation between the lead wire and the tube shell.

[0013] The AMB ceramic substrate is a silicon nitride AMB ceramic substrate.

[0014] A method for stacking and assembling multiple substrates of a radiation-resistant point-of-load power supply comprises the following steps:

[0015] Solder the AMB ceramic substrate to the tube shell, and mount the silver-copper bracket and the power inductor, power chip, ceramic capacitor and tantalum capacitor in the power chipset on the AMB ceramic substrate;

[0016] Bonding the Al2O3 thick film multilayer ceramic substrate to the AMB ceramic substrate and baking the substrate after bonding;

[0017] Mounting the control chip, chip capacitors, thick film resistor blocks and thin film resistor network in the control chip set on an Al2O3 thick film multilayer ceramic substrate, and baking after bonding;

[0018] Glue and reinforce the components in the power chipset and control chipset, and then bake them after reinforcement;

[0019] The power chip and the AMB ceramic substrate, as well as the control chip, thick-film resistor block, thin-film resistor network and the Al2O3 thick-film multilayer ceramic substrate, are interconnected by wire bonding. The AMB ceramic substrate and the Al2O3 thick-film multilayer ceramic substrate are also interconnected by wire bonding to obtain the internal circuit structure.

[0020] The internal circuit structure is pre-baked, and the tube shell and cover are sealed using a parallel seam welding machine to obtain the overall circuit structure.

[0021] Before welding the AMB ceramic substrate and the tube shell, the tube shell needs to be pre-processed, which specifically includes the following steps:

[0022] Scrub the tube shell with acetone and air dry;

[0023] Scrub the tube shell with anhydrous ethanol and air dry;

[0024] Printing ink on the tube shell;

[0025] After printing, bake at 200℃ for 2h.

[0026] After the bonding interconnection is completed, the bonding strength of the wire is tested.

[0027] After the sealing is completed, the overall circuit structure is tested for leaks and PIND.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The present invention uses both an AMB ceramic substrate and an Al2O3 thick-film multilayer ceramic substrate. The AMB ceramic substrate is reflow-soldered onto a tube shell, and then the Al2O3 thick-film multilayer ceramic substrate is bonded to the AMB ceramic substrate. The AMB ceramic copper-clad substrate has the characteristics of high thermal conductivity and ultra-low impedance and is used for power circuit routing. The Al2O3 thick-film multilayer substrate is used for control circuit wiring. The two substrates are electrically interconnected by wire bonding. The multi-substrate stacking structure improves the assembly density of the radiation-resistant load point power supply under large load current conditions, reduces the conduction band impedance and substrate thermal resistance, and improves the power density and conversion efficiency of the load point power supply.

[0030] Furthermore, the AMB ceramic substrate is a silicon nitride AMB ceramic substrate. The thermal conductivity of silicon nitride is above 80, while the thermal conductivity of the conventionally used alumina material is below 30. Silicon nitride has obvious advantages over the thermal conductivity of alumina, and can significantly reduce the thermal resistance of the radiation-resistant load point power supply and improve the conversion efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0032] Figure 1 A cross-sectional view of a multi-substrate stacking structure of a radiation-resistant point-of-load power supply according to the present invention;

[0033] Figure 2 A schematic diagram of the multi-substrate stacking process assembly of the radiation-resistant point-of-load power supply of the present invention;

[0034] Figure 3 This is a schematic diagram of an assembly of an embodiment of the present invention;

[0035] Figure 4 It is a cross-sectional view of the thick film multi-layer substrate structure in the prior art;

[0036] Figure 5 This is a schematic diagram of the assembly process of a thick film multi-layer substrate in the prior art.

[0037] Among them: 1-tube shell, 2-solder paste, 3-AMB ceramic substrate, 4-silver copper bracket, 5-glass insulator, 6-lead, 7-cover, 8-inductor, 9-power chip, 10-pressure bonding wire, 11-chip capacitor, 12-conductive glue, 14-control chip, 15-Al2O3 thick film multilayer ceramic substrate. DETAILED DESCRIPTION

[0038] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of 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. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0039] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort shall fall within the scope of protection of the present invention.

[0040] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0041] In the description of the embodiments of the present invention, it should be noted that if the terms "upper," "lower," "horizontal," "inner," etc. appear, the orientation or positional relationship indicated is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the inventive product is typically placed when in use. These terms are merely for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first," "second," etc. are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0042] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0043] In the description of the embodiments of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0044] The present invention is described in further detail below with reference to the accompanying drawings:

[0045] See also Figure 1 and Figure 2, which is a schematic diagram of the multi-substrate stacking structure and assembly diagram of the radiation-resistant load point power supply in the present invention, including a tube shell 1, an AMB ceramic substrate 3, a power chipset, a control chipset and an Al2O3 thick-film multilayer ceramic substrate 15; the AMB ceramic substrate 3 is welded on the tube shell 1, the Al2O3 thick-film multilayer ceramic substrate 15 is bonded to the AMB ceramic substrate 3, the AMB ceramic substrate 3 and the Al2O3 thick-film multilayer ceramic substrate 15 are interconnected by metal wire bonding, the power chipset is mounted on the AMB ceramic substrate 3, the power chipset includes a power inductor, a power chip, a ceramic capacitor and a tantalum capacitor, the power The components in the chipset are mounted on the AMB ceramic substrate 3 using solder paste. A silver-copper bracket 4 is also welded on the AMB ceramic substrate 3. The silver-copper bracket 4 is led out through a lead 6. The lead 6 passes through the tube shell 1 through a glass insulator 5. The glass insulator 5 is used to electrically isolate the lead 6 from the tube shell 1. The control chipset is mounted on an Al2O3 thick-film multilayer ceramic substrate 15. The control chipset includes a control chip, chip capacitors, thick-film resistor blocks and a thin-film resistor network. The components in the control chipset are mounted on the Al2O3 thick-film multilayer ceramic substrate 15 using an adhesive. The cover plate 7 and the tube shell 1 are welded using parallel seam welding.

[0046] Shell 1 supports the AMB ceramic substrate 3 within it. The fully sealed shell 1 provides mechanical and environmental protection for the internal circuitry. When selecting a shell, consider the sealing type, plating, package form, and package size. For radiation-resistant point-of-load power supplies with low-voltage, high-current outputs, shell 1 utilizes a 10# cold-rolled steel housing with good airtightness, high thermal conductivity, and strong mechanical resistance. Cover 7 utilizes 4J42 metal material. Shell 1 and cover 7 are nickel-plated with a thickness of 3μm to 11.4μm. AMB ceramic copper-clad substrates are used for wiring the power portion of the circuit. The AMB substrate is a substrate with a conductor pattern made of copper on the front and back of a silicon nitride ceramic substrate. To minimize conduction band impedance and maximize conversion efficiency, a 0.32mm-thick AMB substrate was designed, with 300μm copper on both the front and back sides, for a total thickness of 0.92mm. The copper-clad conduction band impedance is 0.06mΩ / □, and the conduction band loss for a current of 10A is 10*10*0.06mΩ=6mW / □. Compared to conventional aluminum oxide, silicon nitride has a thermal conductivity of over 80, while aluminum oxide has a thermal conductivity of less than 30. An Al2O3 thick-film multilayer ceramic substrate is used for control wiring. Conductors and resistors are printed onto the ceramic substrate using a traditional thick-film screen printing process. The substrate thickness is 0.635mm. Planar inductors, control chips, power chips, ceramic capacitors, tantalum capacitors, thick-film resistor blocks, and thin-film resistor networks are essential components of the radiation-resistant point-of-load power supply. Planar inductors are used to store and transfer energy, control chips and power chips are used for pulse width control and power conversion respectively, tantalum capacitors are used for energy storage filtering, ceramic capacitors, thick film resistor blocks, thin film resistor networks, etc. are used for filtering, loop regulation, etc.

[0047] The present invention provides a multi-substrate stacking assembly method for a radiation-resistant point-of-load power supply, comprising the following steps:

[0048] S1, pre-treating and printing the tube shell 1. The tube shell 1 is cleaned, first scrubbed with acetone and air-dried; then scrubbed with anhydrous ethanol and air-dried; and printed with ink on the tube shell 1. After printing, the tube shell 1 is baked at 200°C for 2 hours.

[0049] S2, welding of the AMB ceramic substrate 3 and components. Solder paste is applied to the interior of the tube shell 1 and the back of the AMB ceramic substrate 3. The solder paste composition is Sn63Pb35Ag2, and the coating method is stencil printing. The tube shell 1 and the AMB ceramic substrate 3 are then reflowed, tinned, and cleaned. After the tinning is completed, solder paste is applied to the front of the AMB ceramic substrate 3. The solder paste composition is Sn63Pb35Ag2, and the coating method is stencil printing. After completion, components are mounted, including planar inductors, chips, PbSn-terminated ceramic capacitors, tantalum capacitors, and silver-copper brackets. The AMB ceramic substrate 3 is then placed in the tinned tube shell 1. After hot plate reflow soldering, it is cleaned, X-rayed, and visually inspected internally for circuits. The reflowed tube shell 1 is then subjected to insulation testing using an insulation impedance tester.

[0050] S3, bonding the Al2O3 thick-film multilayer ceramic substrate 15. Fix the welded AMB ceramic substrate 3 and the component shell 1 on a heating table. Use a scraper or brush to evenly apply an appropriate amount of thermally conductive adhesive to the back side of the Al2O3 thick-film multilayer ceramic substrate 15 and the corresponding bonding areas on the front side of the AMB ceramic substrate 3. Place the Al2O3 thick-film multilayer ceramic substrate 15 in the corresponding position on the AMB ceramic substrate, ensuring that at least 50% of the adhesive overflows around the edges of the Al2O3 thick-film multilayer ceramic substrate 15. After bonding, bake at 150°C for 2 hours.

[0051] S4, bonding of PbAg chip capacitors, thick-film resistor blocks, chips, and thin-film resistor networks. Use conductive adhesive to bond PbAg chip capacitors and chips with electrodes on the back, and use insulating adhesive to bond chips without electrodes on the back, thick-film resistor blocks, and thin-film resistor networks. Bond the components to the Al2O3 thick-film multilayer ceramic substrate 15. It is required that adhesive overflows around the bonding surface of the components, and the adhesive cannot adhere to the upper surface of the components. After bonding with the conductive adhesive, bake at 150°C for 2 hours, and after bonding with the insulating adhesive, bake at 150°C for 4 hours. When different adhesives are cured in the same oven and at the same temperature, the upper limit of the curing time is based on the longest curing time of the adhesive.

[0052] S5, Passive chip component reinforcement. Passive chip components that are welded or bonded require adhesive reinforcement. For welded components, the reinforcement glue is applied to the center of the junction between the two sides of the chip component and the substrate. The reinforcement glue cannot contact the metalized end of the component. For passive chip components bonded with conductive adhesive, the reinforcement glue is applied to the center of the junction between the two sides of the chip component and the substrate. The reinforcement glue can contact the metalized end of the component. After reinforcement, bake at 150°C for 2 hours.

[0053] S6, Bonding and Non-destructive Lacking. For soldered or bonded chips, thick-film resistor blocks, thin-film resistor networks, and two substrates, silicon-aluminum wire or gold wire bonding is performed. Silicon-aluminum wire is used to connect the soldered chip and the AMB nickel-plated copper conductor, or to connect the bonded chip and the gold conductor, or to connect the AMB ceramic substrate 3 and the Al2O3 thick-film multilayer ceramic substrate 15. Gold wire is used to connect the thick-film resistor block, thin-film resistor network, and the gold conductor. The bonding wire diameter is selected based on the chip's pad size and the actual overcurrent requirements in the application. After bonding is completed, a non-destructive lacking test, or bond strength test, is required to ensure the stability of the pressure welding process parameters.

[0054] S7, Sealing, Leakage Detection, and PIND Testing. Prepare the welding roller and packaging fixture, pre-bake the circuit at 150°C for 24 hours, and seal the circuit using a parallel seam welder. After sealing, perform leak detection and PIND testing to ensure that the circuit leakage rate meets the requirements and there is no loose material inside.

[0055] The present invention combines a high-thermal-conductivity, ultra-low-impedance AMB ceramic substrate with a traditional Al2O3 thick-film multilayer ceramic substrate. Power traces are routed on the AMB ceramic substrate 3, and control traces are routed on the traditional Al2O3 thick-film multilayer ceramic substrate 15. The two substrates are interconnected via a bonding process. This method reduces wiring losses. A 10A current flowing through a palladium-silver conductive strip on a traditional thick-film substrate and a copper-clad conductive strip on an AMB substrate generates losses of 1.5W / □ and 6mW / □, respectively, where □ is the ratio of the conductive strip length to width. The method proposed by the present invention reduces conductive strip losses and improves conversion efficiency in radiation-resistant point-of-load power supplies. Components can be assembled not only on the bottom AMB substrate but also on the top traditional thick-film multilayer substrate, increasing the assembly density and power density of the radiation-resistant point-of-load power supply. The bottom substrate is a silicon nitride AMB substrate. Compared to conventional aluminum oxide, silicon nitride has a thermal conductivity of over 80, while aluminum oxide has a thermal conductivity of less than 30. The use of AMB substrates reduces the thermal resistance of radiation-resistant point-of-load power supplies and improves conversion efficiency.

[0056] See also Figure 3This is an assembly diagram of a radiation-resistant point-of-load power supply according to an embodiment of the present invention. A multi-substrate stacking structure is applied to a radiation-resistant point-of-load power supply with an input voltage of 4.75 to 30V, an output voltage of 1.2 to 5.5V, and a maximum load current of 4.5A. The AMB ceramic substrate 3 is welded to the tube shell 1 using a reflow process. Simultaneously, the power inductor L1, chip U2, tantalum capacitor C8, ceramic capacitors C5, C7, and C9 are welded to the AMB ceramic substrate 3. Thermally conductive adhesive is then used to bond the Al2O3 thick-film multilayer ceramic substrate 15 to the AMB substrate. The chip U1, capacitors C1 to C4, thin-film resistor network R1, R4-1, R4-2, and thick-film resistor block R8 are then bonded. Passive chip components such as capacitors are reinforced with adhesive, and chip bonding and short-circuit bonding are performed. Finally, the module is sealed and welded.

[0057] The maximum dimensions of the tube shell 1 are 32*32*7mm. It is made of 10# cold-rolled steel, which offers excellent airtightness, high thermal conductivity, and strong mechanical resistance. The external leads are copper-core composite leads with a diameter of 1mm. The AMB ceramic substrate 3 measures 28.10*26*0.32mm, with a copper coating thickness of 300μm on both the front and back sides. The total thickness of the AMB ceramic substrate 3 is 0.92mm and is made of silicon nitride. The Al2O3 thick-film multilayer ceramic substrate 15 measures 10.95*6.5*0.635mm and is 8-12μm thick. It is made of 96% Al2O3.

[0058] Under the test conditions of input 5V and output 3.3V / 1A, the module conversion efficiency of the radiation-resistant load point power supply of the present invention is 93.4%, while the module conversion efficiency of the traditional multi-layer post-film hybrid process is 88.8%. Compared with the two, the efficiency of the module using the present invention is improved by 4.6%.

[0059] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A multi-substrate stacking structure for a radiation-resistant point-of-load power supply, characterized in that: It comprises a tube shell (1), an AMB ceramic substrate (3), a power chipset, a control chipset and an Al2O3 thick film multilayer ceramic substrate (15); The AMB ceramic substrate (3) is welded on the tube shell (1), the Al2O3 thick film multilayer ceramic substrate (15) is bonded on the AMB ceramic substrate (3), the AMB ceramic substrate (3) and the Al2O3 thick film multilayer ceramic substrate (15) are interconnected by metal wire bonding, the power chipset is mounted on the AMB ceramic substrate (3), the control chipset is mounted on the Al2O3 thick film multilayer ceramic substrate (15), and the cover plate (7) and the tube shell (1) are welded by parallel seam welding.

2. The multi-substrate stacking structure of the radiation-resistant point-of-load power supply according to claim 1, wherein: The power chip group comprises an inductor, a power chip, a ceramic capacitor and a tantalum capacitor, and the components in the power chip group are mounted on an AMB ceramic substrate (3) through solder paste.

3. The multi-substrate stacking structure of the radiation-resistant point-of-load power supply according to claim 1, wherein: The control chip set comprises a control chip, a chip capacitor, a thick film resistor block and a thin film resistor network. The components in the control chip set are mounted on an Al2O3 thick film multilayer ceramic substrate (15) through an adhesive.

4. The multi-substrate stacking structure of the radiation-resistant point-of-load power supply according to claim 1, wherein: A silver-copper bracket (4) is welded on the AMB ceramic substrate (3), and the silver-copper bracket (4) is led out of the tube shell (1) through a lead wire (6).

5. The multi-substrate stacking structure of the radiation-resistant point-of-load power supply according to claim 4, wherein: The lead wire (6) passes through the tube shell (1) via a glass insulator (5), and the glass insulator (5) is used for electrical isolation between the lead wire (6) and the tube shell (1).

6. The multi-substrate stacking structure of the radiation-resistant point-of-load power supply according to claim 1, wherein: The AMB ceramic substrate (3) is a silicon nitride AMB ceramic substrate.

7. A method for assembling multiple substrates of a radiation-resistant point-of-load power supply, characterized in that: The following steps are involved: The AMB ceramic substrate (3) is welded to the tube shell (1), and the silver-copper bracket (4) and the power inductor, power chip, ceramic capacitor and tantalum capacitor in the power chip group are mounted on the AMB ceramic substrate (3); Bonding an Al2O3 thick film multilayer ceramic substrate (15) to an AMB ceramic substrate (3), and baking the substrate after bonding; Mounting the control chip, chip capacitors, thick film resistor blocks and thin film resistor networks in the control chip group on an Al2O3 thick film multilayer ceramic substrate (15), bonding and baking the substrate; Glue and reinforce the components in the power chipset and control chipset, and then bake them after reinforcement; Conducting wire bonding interconnections between the power chip and the AMB ceramic substrate (3), and between the control chip, the thick film resistor block, the thin film resistor network, and the Al2O3 thick film multilayer ceramic substrate (15), and conducting wire bonding interconnections between the AMB ceramic substrate (3) and the Al2O3 thick film multilayer ceramic substrate (15), thereby obtaining an internal circuit structure; The internal circuit structure is pre-baked, and the tube shell (1) and the cover plate (7) are sealed and welded using a parallel seam welding machine to obtain an integral circuit structure.

8. The method for assembling multiple substrates of a radiation-resistant point-of-load power supply according to claim 7, wherein: Before welding the AMB ceramic substrate (3) and the tube shell (1), the tube shell (1) needs to be pre-processed, which specifically includes the following steps: Scrub the tube shell (1) with acetone and air dry; Scrub the tube shell (1) with anhydrous ethanol and air dry; Printing ink on the tube shell (1); After printing, bake at 200℃ for 2h.

9. The method for assembling multiple substrates of a radiation-resistant point-of-load power supply according to claim 7, wherein: After the bonding interconnection is completed, the bonding strength of the wire is tested.

10. The method for assembling multiple substrates of a radiation-resistant point-of-load power supply according to claim 7, wherein: After the sealing is completed, the overall circuit structure is tested for leaks and PIND.

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