Aluminum electrolytic capacitor of capacitor module in AI server power supply and processing method thereof

Abstract

An aluminum electrolytic capacitor of a capacitor module in an AI server power supply comprises an aluminum shell, a core bag is arranged in the aluminum shell, the aluminum shell is a bottomless aluminum shell, an anode terminal and a cathode terminal are arranged at the two ends of the aluminum shell respectively, and the core bag is formed by winding an anode foil, a cathode foil and electrolytic paper. The anode foil and the cathode foil extend out from two different end parts of the core cladding, the extending end of the anode foil is connected with the anode terminal, the extending end of the cathode foil is connected with the cathode terminal, a cover plate is arranged between the anode terminal and the aluminum shell, the anode foil and the anode terminal are separated from the aluminum shell by the cover plate, and the cathode terminal is connected with the periphery of the aluminum shell. Compared with the prior art, the ripple resistance of the aluminum electrolytic capacitor is improved, the equivalent series resistance is remarkably reduced, the size is reduced, the size is reduced by 15-20% compared with a traditional product under the same capacity, the service life is prolonged, and the safety is improved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of aluminum electrolytic capacitors, in particular to an aluminum electrolytic capacitor for an AI server power supply capacitor module and a processing method thereof. BACKGROUND

[0002] The aluminum electrolytic capacitor is widely applied to scenes such as power supply filtering and energy storage due to low cost, high voltage resistance, long service life and strong self-recovery capability; however, with the AI server computing power upgrading from GB100 to GB300, the power demand jumps from 22KW to 88KW, and the traditional aluminum electrolytic capacitor gradually exposes the following key defects: 1. structural defects, the electrode is connected with the core package through a foil strip, the metal resistance of the foil strip and the contact resistance at the riveting position cause the equivalent series resistance (ESR) to be high, and the foil strip increases the volume of the core package, so the compact space requirement of the AI server cannot be met; 2. process limitations, the uneven distribution of the traditional full formation aluminum foil oxide layer, and the fine pore structure of the high specific capacity aluminum foil easily cause the electrolyte to be insufficiently immersed, further increasing the ESR, the low-pressure immersion process of the immersion pot has the problem of insufficient electrolyte penetration, the residual bubbles reduce the dielectric performance, and the closed structure of the bottom aluminum shell limits heat dissipation and has insufficient explosion-proof performance; 3. performance bottleneck, the traditional CD29 series single body has only a ripple resistance of 3.8A (120Hz, 25 DEG C), and cannot withstand the high-frequency ripple impact of the high-power AI chip, so the response speed is lagging, which becomes a bottleneck of the power supply stability. SUMMARY

[0003] The application aims to solve the technical problems of the prior art.

[0004] To solve the above technical problems, the application adopts the following technical scheme: An aluminum electrolytic capacitor for an AI server power supply capacitor module, comprising an aluminum shell, a core package arranged in the aluminum shell, the aluminum shell being a bottomless aluminum shell, an anode connection end and a cathode connection end arranged at two ends of the aluminum shell respectively, the core package being wound by an anode foil, a cathode foil and electrolytic paper, the anode foil and the cathode foil extending from two different end portions of the core package, the extending end of the anode foil being connected with the anode connection end, the extending end of the cathode foil being connected with the cathode connection end, a cover plate being arranged between the anode connection end and the aluminum shell, the cover plate separating the anode foil, the anode connection end and the aluminum shell, and the cathode connection end being connected with the periphery of the aluminum shell.

[0005] Further, the anode connection end and the cathode connection end adopt a round sheet structure, welding grooves are uniformly distributed on the surfaces of the anode connection end and the cathode connection end, and the anode connection end and the cathode connection end are connected with the corresponding anode foil and cathode foil into an integral whole through laser welding in the welding grooves.

[0006] Further, the anode terminal and the cathode terminal are provided with terminals on one side, and the terminals are processed with terminal holes.

[0007] Further, the cover plate is made of a phenolic resin cover plate, the cover plate is arranged at the end opening of the aluminum shell, the cover plate is sleeved on the outer side of the anode foil, the end of the aluminum shell is processed with a turned edge, the turned edge presses the cover plate, and the cover plate is provided with protrusions around the cover plate.

[0008] Further, the periphery of the cathode terminal is connected to the aluminum shell as a whole through laser welding.

[0009] Further, the anode foil wrapped in the core package is an oxidized area, and the part extending out of the core package is an unoxidized area.

[0010] Further, the anode terminal is processed with a liquid injection hole, and a rubber plug is arranged in the liquid injection hole.

[0011] Further, the aluminum shell is processed with an explosion-proof valve on the side surface.

[0012] A processing method of an aluminum electrolytic capacitor of a capacitor module in an AI server power supply, comprising the following steps, Step one: select anode foil, cathode foil and electrolytic paper to wind into a core package, and leave a margin on the anode foil and the cathode foil during winding, and the anode foil and the cathode foil protrude from the core package on the side surface; Step two: polish the protruding end surface of the anode foil to meet the roughness requirement; Step three: assemble the aluminum shell, the core package, the cover plate, the anode terminal and the cathode terminal, connect the anode terminal with the protruding end of the anode foil, connect the cathode terminal with the protruding end of the cathode foil, and weld the cathode terminal with the periphery of the aluminum shell as a whole through laser welding; Step four: inject electrolyte into the aluminum shell through the liquid injection hole by using high-pressure liquid injection method; Step five: normal temperature aging, and install a rubber plug on the liquid injection hole after the leakage current is stable; Step six: high temperature aging; Step seven: test the aluminum electrolytic capacitor.

[0013] Compared with the prior art, the aluminum electrolytic capacitor of a capacitor module in an AI server power supply and the processing method thereof have the following beneficial effects: 1. The ripple current of the aluminum electrolytic capacitor is increased from 3.8A (120Hz, 25℃) to 20A, which meets the demand of 88KW AI server power supply; 2. The ESR is significantly reduced: the equivalent series resistance is reduced from 80mΩ of the traditional one to below 25mΩ; 3. Volume reduction: 15-20% smaller volume than traditional products for the same capacity; 4. Life extension: high-temperature (85℃) load life ≥10000h, 50% higher than traditional products; 5. Safety improvement: explosion-proof valve response pressure 0.5-0.6MPa, pressure relief within 10ms when overpressure, avoiding explosion risk. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 is a structural schematic diagram of the present application; Figure 2 is a top view of the present application; Figure 3 is a structural schematic diagram of the anode foil of the present application; Among them, 1 is an aluminum shell, 2 is an anode terminal, 3 is a cathode terminal, 4 is a terminal, 5 is a terminal hole, 6 is an anode foil, 7 is a cathode foil, 8 is an electrolytic paper, 9 is a waist-shaped welding groove, 10 is a cover plate, 11 is a flange, 12 is a rubber plug, and 13 is an explosion-proof valve. DETAILED DESCRIPTION

[0015] The technical solutions in the embodiments of the present application will be described clearly and completely below.

[0016] As shown in Figure 1 and Figure 2 , an aluminum electrolytic capacitor of a capacitor module in an AI server power supply includes an aluminum shell 1, a core package is arranged in the aluminum shell 1, the aluminum shell 1 adopts a bottomless aluminum shell, an anode terminal 2 and a cathode terminal 3 are arranged at two ends of the aluminum shell 1 respectively, the anode terminal 2 and the cathode terminal 3 adopt a round sheet structure, a terminal 4 is arranged on one side of the anode terminal 2 and the cathode terminal 3, and a terminal hole 5 is processed in the terminal 4.

[0017] The core package is wound by an anode foil 6, a cathode foil 7, and an electrolytic paper 8, the anode foil 6 and the cathode foil 7 extend from two different end portions of the core package, the extending end of the anode foil 6 is connected with the anode terminal 2, and the extending end of the cathode foil 7 is connected with the cathode terminal 3, in this embodiment, waist-shaped welding grooves 9 are uniformly distributed on surfaces of the anode terminal 2 and the cathode terminal 3, and the anode terminal 2 and the cathode terminal 3 are connected with corresponding anode foils 6 and cathode foils 7 into a whole through laser welding in the waist-shaped welding grooves 9.

[0018] Compared with traditional aluminum electrolytic capacitors, the present application cancels the lead foil strip, directly connects the anode foil with the anode terminal and the cathode foil with the cathode terminal through laser welding, and eliminates the lead foil strip resistance and riveting contact resistance.

[0019] In the embodiment, the anode foil 6 is wrapped in the core package as the oxidized area, and the unoxidized area is extended out of the core package and connected with the anode terminal 2 to reduce the contact resistance of the aluminum foil edge.

[0020] The cover plate 10 is arranged between the anode terminal 2 and the aluminum shell 1, and separates the anode foil 6 and the anode terminal 3 from the aluminum shell 1. In the embodiment, the cover plate 10 is a phenolic resin cover plate. The cover plate 10 is arranged at the end opening of the aluminum shell 1 and is sleeved on the outer side of the anode foil 6. The end of the aluminum shell 1 is processed with a flange 11 to press the cover plate 10. The cover plate 10 is provided with a protrusion around the periphery to separate the anode terminal 2 from the aluminum shell 1. The cathode terminal 3 is connected with the periphery of the aluminum shell 1. In the embodiment, the periphery of the cathode terminal 3 is connected with the aluminum shell 1 as a whole by laser welding.

[0021] The anode terminal 2 is processed with a liquid injection hole for injecting electrolyte into the aluminum shell. The liquid injection hole is provided with a rubber plug 12 to block the liquid injection hole.

[0022] In order to improve the safety performance of the aluminum electrolytic capacitor during use, the aluminum shell side is also processed with an explosion-proof valve 13. In the embodiment, the wall thickness of the aluminum shell 1 is 0.8 mm. The surface of the aluminum shell 1 is processed with a “V” shaped explosion-proof valve. The depth of the “V” shaped explosion-proof valve is 0.3 mm, and the angle is 60°. The explosion-proof valve not only realizes rapid pressure relief under overpressure and improves safety performance, but also reduces the occupation of the bottom space and reduces the volume of the aluminum electrolytic capacitor.

[0023] A method for processing an aluminum electrolytic capacitor of a capacitor module in an AI server power supply, comprising the following steps, Step one: select an anode foil 6, a cathode foil 7, and an electrolytic paper 8 to wind into a core package. In the winding process, the anode foil 6 and the cathode foil 7 both have a surplus, and the side of the anode foil 6 and the cathode foil 7 protrudes out of the core package. Among them, the unoxidized area of the anode foil 6 protrudes out of the core package. Step two: polish the protruding end face of the anode foil 6 to meet the roughness requirement, and the roughness Ra≤1.6μm. Step three: assemble the aluminum shell 1, the core package, the cover plate 10, the anode terminal 2, and the cathode terminal 3. Through laser welding, the anode terminal 2 is connected with the protruding end of the anode foil 6, the cathode terminal 3 is connected with the protruding end of the cathode foil 7, and the cathode terminal 7 is welded with the periphery of the aluminum shell 1 as a whole. A 1064nm fiber laser welding machine is used. The anode terminal welding power is 120-150W, the cathode terminal is 80-100W, the welding speed is 5-8mm / s, and a fusion core with a diameter of 0.8-1.2mm is formed. Step four: replace the normal pressure immersion with 0.3-0.5MPa high pressure injection to inject electrolyte into the aluminum shell through the liquid injection hole. Step five: normal temperature aging, after the leakage current is stable, install rubber plug 12 at the liquid injection hole, and age at 25℃ under 450V constant voltage for 8-10h until the leakage current is stable and ≤1mA, and then seal; Step six: high temperature aging, age at 85℃ under 420V constant voltage for 6h; Step seven: test the prepared aluminum electrolytic capacitor.

[0024] Specifically, taking a CD25H 400V1200μF aluminum electrolytic capacitor as an example.

[0025] As shown in Figure 3 The anode foil is selected to be 540VF low specific capacity aluminum foil, and the thickness is 80-100nm and the width is 54mm. The surface of the region with a width of 51mm on the side of the anode foil is subjected to oxidation treatment, the corrosion hole diameter is ≥5μm, and the hole depth is ≤30μm. The region with a width of 3mm on the side of the anode foil is not subjected to oxidation treatment. In this way, the anode foil is pretreated to reduce the electrolyte migration resistance and reduce the ESR. The cathode foil is selected to be 20V-22V aluminum foil, and the width is 57mm. The electrolytic paper is selected to be 190 type electrolytic paper, and the thickness is 25μm. During winding, a winding machine is used to wind according to the order of one layer of electrolytic paper→one layer of anode foil→two layers of electrolytic paper→one layer of cathode foil→one layer of electrolytic paper. The prepared core package has a diameter of 34mm and a height of 60mm, no lead foil strip, and the anode foil with a width of 3mm extends out of the core package, and the cathode foil with a width of 6mm extends out of the core package.

[0026] The end surface of the anode foil is polished to ensure that the roughness Ra of the welding surface is ≤1.2μm, and the cathode foil itself is relatively soft and does not need to be polished.

[0027] The aluminum shell, the core package, the cover plate, the anode connecting end and the cathode connecting end are assembled. A 1064nm fiber laser welding machine is used. The anode foil and the anode connecting end are welded at a welding power of 140W and a welding speed of 6mm / s. The end surface of the anode foil and the welding groove of the anode connecting end are welded. The cathode foil and the cathode connecting end are welded at a welding power of 90W. After the cathode foil is bent, the cathode connecting end and the welding groove of the cathode connecting end are welded. The welding speed is 7mm / s. Then, the cathode connecting end and the aluminum shell are welded into a whole.

[0028] Then, the electrolyte is injected under a pressure of 0.4MPa, and the injection amount is 12±0.5g. The electrolyte ratio is as follows: 70% ethylene glycol+25% ammonium adipate+5% deionized water, filtered through a 0.2μm filter membrane.

[0029] At normal temperature 25℃, the normal temperature 450V aging is performed for 9h, and the butyl rubber plug is used to seal when the leakage current is stable and is 0.8mA.

[0030] At high temperature aging 85℃ environment, 420V aging is performed for 6h; Finally, test: according to GB / T 24794 standard test, capacity deviation is ≤±20%, ESR=22mΩ, 120Hz, 25℃ under ripple current 20A, high temperature life test (85℃, 400V) 10000h after capacity attenuation ≤10%.

[0031] The CD25H 400V1200μF capacitor produced by the above process successfully increases the ripple resistance from 3.8A to 20A, and the volume is reduced by 18% compared with the traditional product of the same specification, which fully meets the high power and small space requirements of GB300 AI server power supply.

[0032] The application is not limited to the described embodiments, and those skilled in the art can make some modifications or changes without departing from the spirit of the application, i.e., the disclosed range, so the protection scope of the application is limited to the range defined in the claims.

Claims

1. An aluminum electrolytic capacitor for a capacitor module in an AI server power supply, comprising an aluminum shell with a core package disposed therein, characterized in that: The aluminum shell adopts a bottomless aluminum shell, and an anode terminal and a cathode terminal are respectively provided at both ends of the aluminum shell. The core package is formed by winding an anode foil, a cathode foil and an electrolytic paper. The anode foil and the cathode foil extend from two different ends of the core package. The extended end of the anode foil is connected to the anode terminal, and the extended end of the cathode foil is connected to the cathode terminal. A cover plate is provided between the anode terminal and the aluminum shell, and the cover plate separates the anode foil and the anode terminal from the aluminum shell. The cathode terminal is connected to the periphery of the aluminum shell.

2. The aluminum electrolytic capacitor of the capacitor module in the AI ​​server power supply according to claim 1, characterized in that: The anode terminal and cathode terminal adopt a disc structure, and welding grooves are distributed on the surfaces of the anode terminal and cathode terminal. The anode terminal and cathode terminal are connected to the corresponding anode foil and cathode foil into a whole by laser welding in the welding grooves.

3. The aluminum electrolytic capacitor of the capacitor module in the AI ​​server power supply according to claim 2, characterized in that: A terminal is extended on one side of the anode terminal and the cathode terminal, and a terminal hole is processed on the terminal.

4. The aluminum electrolytic capacitor of the capacitor module in the AI ​​server power supply according to claim 2, characterized in that: The cover plate is made of phenolic resin and is arranged at the opening at one end of the aluminum shell. The cover plate is sleeved on the outside of the anode foil. The end of the aluminum shell is processed with a flange, which presses the cover plate. The cover plate is provided with a protrusion around the periphery, which separates the anode terminal from the aluminum shell.

5. The aluminum electrolytic capacitor of the capacitor module in the AI ​​server power supply according to claim 2, characterized in that: The periphery of the cathode terminal is connected to the aluminum shell through laser welding to form a whole.

6. The aluminum electrolytic capacitor of the capacitor module in the AI ​​server power supply according to claim 2, characterized in that: The anode foil wrapped in the core package is an oxidized area, and the area extending outside the core package is an unoxidized area.

7. The aluminum electrolytic capacitor of the capacitor module in the AI ​​server power supply according to claim 1, characterized in that: A liquid injection hole is processed on the anode terminal, and a rubber plug is arranged in the liquid injection hole.

8. The aluminum electrolytic capacitor of the capacitor module in the AI ​​server power supply according to claim 1, characterized in that: An explosion-proof valve is processed on the side of the aluminum shell.

9. The method for processing aluminum electrolytic capacitors for capacitor modules in AI server power supplies according to any one of claims 1 to 8, characterized in that: The following steps are included: Step 1: Select anode foil, cathode foil, and electrolytic paper and wind them into a core package. During the winding process, both the anode foil and the cathode foil are left with margins, and the sides of the anode foil and the cathode foil protrude from the core package. Step 2: Grind the protruding end surface of the anode foil to meet the roughness requirements; Step 3: Assemble the aluminum shell, core package, cover plate, anode terminal and cathode terminal. Connect the anode terminal to the protruding end of the anode foil, connect the cathode terminal to the protruding end of the cathode foil, and weld the cathode terminal to the periphery of the aluminum shell into a whole. Step 4: Use high-pressure injection method to inject electrolyte into the aluminum shell through the injection hole; Step 5: Aging at room temperature. After the leakage current stabilizes, install a rubber plug at the injection hole. Step 6: High temperature aging; Step 7: Test the manufactured aluminum electrolytic capacitor.

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