A preparation method of a potting pulse capacitor module

Abstract

The application belongs to the field of preparation of potting capacitors, and particularly relates to a preparation method of a potting pulse capacitor module. The potting pulse capacitor module comprises a potting shell, a capacitor module arranged in the potting shell, and a potting adhesive layer filled in the potting shell to fix the capacitor module. A plurality of grooves are arranged on the inner wall of the potting shell and are arranged in the vertical direction. The preparation method comprises the following steps: air gun cleaning, plasma treatment, pre-coating of a potting primer, multiple times of potting of the potting adhesive, and solidification forming. The application limits the structure and preparation method of the potting pulse capacitor module, so that the product after potting is compact and has no pores, the structural strength of the product after preparation is ensured, the product can be used in a high-impact and vibration environment, and the use requirements of the potting pulse capacitor module are met.

Description

Technical Field

[0001] This invention belongs to the field of potted capacitor preparation, specifically relating to a method for preparing a potted pulse capacitor module. Background Technology

[0002] Pulse capacitor modules are generally used in high-voltage discharge applications. Typically, the assembled capacitor modules are potted. Potting with encapsulant isolates the cavity from air, preventing high-voltage chip ignition. Another advantage is that it strengthens the overall structural integrity of the product, allowing it to operate under high impact and vibration conditions. However, the quality of the potting compound has a significant impact on product performance. Generally, the potting compound must be dense and free of pores. Currently, pores easily form at the contact point between the potting compound and the outer casing, a problem that has consistently plagued manufacturers and requires further improvement. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing a potted pulse capacitor module.

[0004] The present invention adopts the following technical solution:

[0005] A method for preparing a potted pulse capacitor module, the potted pulse capacitor module comprising a potting shell, a capacitor module disposed in the potting shell, and a potting adhesive layer filling the potting shell to fix the capacitor module, wherein the inner wall of the potting shell is provided with a plurality of grooves, the plurality of grooves being spaced apart along the vertical direction on the inner wall of the potting shell;

[0006] The method for preparing the encapsulated pulse capacitor module specifically includes the following steps:

[0007] Step 1: Use an air gun to clean the inner wall of the potting shell and the welded capacitor module;

[0008] Step 2: The cleaned potting shell and capacitor module are sent into the cavity of the plasma treatment equipment. The plasma treatment equipment is evacuated to 50pa and the power of the plasma treatment equipment is adjusted to 200-400W. The mixed gas of oxygen and argon forms a luminous plasma glow, which is used to treat the potting shell and capacitor module for 3-8 minutes.

[0009] Step 3: After the process is completed, remove the potting shell and capacitor module from the plasma equipment, and apply potting primer to the inner wall of the potting shell within 2 hours. When applying, first fill the plastic-sealed shell with potting primer, let it stand for 8-15 minutes and then pour it out. Then use a brush to smooth the inner wall of the potting shell.

[0010] Step 4: Place the potting shell coated with potting primer into an oven and cure at 70-90℃ for 10-20 minutes.

[0011] Step 5: Assemble the plasma-treated capacitor mold into the potting shell, first fill it with one-third of the potting adhesive, then put the whole thing into the vacuum equipment and evacuate for 4-6 minutes; then fill it with another one-third of the potting adhesive, and put the whole thing into the vacuum equipment and evacuate for 4-6 minutes again, repeating this process until the potting adhesive is full.

[0012] Step 6: Place the potting shell filled with potting adhesive at 25°C for 2-4 hours to complete the initial curing; then put it into an oven and cure it at 75-85°C for 1-3 hours to obtain the potted pulse capacitor module.

[0013] Furthermore, the capacitor module includes two lead frames arranged opposite each other, a plurality of capacitor chip groups spaced apart between the two lead frames, and two solder layers respectively disposed inside the two lead frames. The capacitor chip group includes a plurality of capacitor chips stacked sequentially in a vertical direction, and the ends of the capacitor chips are connected to the opposite solder layers.

[0014] Furthermore, the lead frame includes a frame body, two connecting pins disposed opposite to the upper end of the frame body, and a plurality of vent holes spaced apart on the frame body. The connecting pins extend outward to the outside of the potting compound layer, and the plurality of vent holes are opposite to the ends of the capacitor chip.

[0015] Furthermore, the top of the potting housing is formed with a downwardly extending positioning groove for the relative connection pins to be inserted.

[0016] Furthermore, the connection pin includes a connection segment connected to the upper end of the frame body and a pin segment arranged perpendicularly to the connection segment, the pin segment being embedded in a relative positioning groove.

[0017] Furthermore, the pin segment is provided with a connection hole.

[0018] Furthermore, the top of the capacitor chip assembly is lower than the top of the potting housing.

[0019] Furthermore, the groove extends outward from the inner wall of the potting shell, and its extension depth is 1-2 mm.

[0020] Furthermore, in step 5, the vacuum equipment is evacuated to 0.1 MPa.

[0021] Furthermore, in step 2, the volume ratio of oxygen to argon is 6:4.

[0022] As can be seen from the above description of the present invention, compared with the prior art, the beneficial effects of the present invention are as follows: This application defines the structure of the potting pulse capacitor module, sets grooves on the inner wall of the potting shell, and specifically defines the preparation method of the potting pulse capacitor module. The potting shell and the capacitor module are first treated by plasma glow discharge, and then a potting primer is coated on the inner wall of the potting shell as an adhesive medium. Then, the potting adhesive is repeatedly poured in and vacuumed multiple times, so that the interior of the potted product is dense and there are no pores. This ensures the structural strength of the prepared product and allows it to be used in high impact and vibration environments, meeting the usage requirements of the potting pulse capacitor module. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of a potted pulse capacitor module;

[0024] Figure 2 This is an exploded view of the potted pulse capacitor module;

[0025] Figure 3 The graph shows the test results of the potted pulse capacitor module prepared in Example 1;

[0026] Figure 4 The test results of the potted pulse capacitor module prepared for Comparative Example 1 are shown in the figure.

[0027] Figure 5 The test results of the potted pulse capacitor module prepared in Comparative Example 2 are shown in the figure.

[0028] Figure 6 The test results of the potted pulse capacitor module prepared in Comparative Example 3 are shown in the figure.

[0029] In the diagram, 1. Encapsulation shell; 2. Capacitor module; 3. Encapsulation layer; 11. Groove; 12. Positioning groove; 21. Lead frame; 22. Capacitor chipset; 23. Solder layer; 24. Frame body; 25. Connecting pin; 251. Connecting section; 252. Pin section; 253. Connecting hole; 26. Vent hole. Detailed Implementation

[0030] The present invention will be further described below through specific embodiments.

[0031] Reference Figures 1 to 2 As shown, a potted pulse capacitor module includes a potting shell 1, a capacitor module 2 disposed in the potting shell 1, and a potting adhesive layer 3 filled in the potting shell 1 to fix the capacitor module 2.

[0032] The potting shell 1 has multiple grooves 11 on its inner wall, which are spaced vertically. Specifically, the grooves 11 extend outward from the inner wall of the potting shell 1 to a depth of 1-2 mm. The multiple grooves 11 increase the roughness of the inner wall of the potting shell 1, thereby increasing the bonding force between the potting adhesive and the potting shell 1. Furthermore, the potting shell 1 is made of polyimide material. Polyimide refers to a type of polymer containing an imide ring (-CO-NR-CO-) in its main chain. It is one of the organic polymer materials with the best comprehensive performance. Its high temperature resistance reaches 400℃, and its long-term operating temperature range is (-200)-300℃. Some have no obvious melting point, high insulation performance, dielectric constant of 4.0 at 10000 Hz, and dielectric loss of only 0.004-0.007, belonging to F to H class insulation, which meets the usage requirements of the potting pulse capacitor module of this application.

[0033] The capacitor module 2 includes two lead frames 21 arranged opposite each other, a plurality of capacitor chip groups 22 spaced apart between the two lead frames 21, and two solder layers 23 respectively disposed inside the two lead frames 21. Specifically, the capacitor chip group 22 includes a plurality of capacitor chips stacked in sequence along the vertical direction, and the ends of the capacitor chips are connected to the opposite solder layers 23. Furthermore, the top of the capacitor chip group 22 is lower than the top of the potting shell 1.

[0034] The lead frame 21 includes a frame body 24, two connecting pins 25 disposed opposite to each other on the upper end of the frame body 24, and a plurality of vent holes 26 spaced apart on the frame body 24. The plurality of vent holes 26 are respectively opposite to a plurality of capacitor chips to facilitate the discharge of gas from the solder paste during the soldering process of the capacitor module 2, resulting in a denser solder layer for the capacitor module 2. Specifically, the connecting pins 25 include a connecting section 251 connected to the upper end of the frame body 24 and a pin section 252 arranged perpendicularly to the upper end of the connecting section 251. The pin section 252 extends outward to the outside of the potting compound layer 3, and a positioning groove 12 extending downward to allow the connecting pins 25 to be embedded is formed on the top of the potting shell 1. The positioning groove 12 allows the capacitor module 2 to be quickly positioned in the potting shell 1. Furthermore, the pin section 252 is provided with a connecting hole 253. During installation of the potted pulse capacitor module, the customer can install the potted pulse capacitor module by using screws to engage with the connecting hole 253 according to installation requirements. Furthermore, the lead frame 21 is made of 4J42 Kovar alloy. 4J42 Kovar alloy is a series of constant-expansion alloys that can match soft glass and ceramics with different coefficients of thermal expansion within a given temperature range by adjusting the nickel content. Its coefficient of thermal expansion and Curie point increase with increasing nickel content. This alloy is widely used in the sealing structure of electronic products. The coefficient of thermal expansion of this iron-nickel material is 5, while the coefficient of thermal expansion of the capacitor chip is 7. The two materials have similar coefficients of thermal expansion, making it less likely for differences in coefficients of thermal expansion to cause product failure.

[0035] The potting compound layer 3 is formed by curing the potting compound. The potting compound is a high thermal conductivity silicone potting compound, which is a two-component, high thermal conductivity addition potting silicone rubber with good thermal conductivity, good high temperature aging resistance, and maintains rubber elasticity in a wide temperature range (-50-200℃) after curing. It has good insulation properties, as well as good waterproof, moisture-proof and anti-aging properties. It can be used for potting protection of high-power electronic components, power modules and circuit boards.

[0036] The method for fabricating a potted pulse capacitor module specifically includes the following steps:

[0037] Step 1: Use an air gun to clean the inner wall of the potting shell 1 and the welded capacitor module 2;

[0038] Step 2: The cleaned potting shell 1 and capacitor module 2 are sent into the cavity of the plasma treatment equipment. The plasma treatment equipment is evacuated to 50pa and the power of the plasma treatment equipment is adjusted to 200-400W. The mixed gas of oxygen and argon forms a luminous plasma glow and treats the potting shell 1 and capacitor module 2 for 3-8 minutes. The volume mixing ratio of oxygen and argon is 6:4 and the gas flow rate is 50ml / min.

[0039] Step 3: After the process is completed, remove the potting shell 1 and the capacitor module 2 from the plasma equipment, and apply a potting primer to the inner wall of the potting shell 1 within 2 hours. When applying the primer, first fill the potting shell 1 with the potting primer, let it stand for 8-15 minutes and then pour it out. Then use a brush to smooth the inner wall of the potting shell 1.

[0040] Step 4: Place the potting shell 1 coated with potting primer into an oven and cure at 70-90℃ for 10-20 minutes;

[0041] Step 5: Install the plasma-treated capacitor module 2 into the potting shell 1. First, fill it with one-third of the potting adhesive, then place the whole unit into a vacuum device and evacuate it to 0.1 MPa for 4-6 minutes. Then fill it with another one-third of the potting adhesive, and place the whole unit into a vacuum device and evacuate it to 0.1 MPa for 4-6 minutes. Repeat this process until the potting adhesive is full.

[0042] Step 6: Place the potting shell 1 filled with potting adhesive at 25°C for 2-4 hours to complete the initial curing; then put it into an oven and cure it at 75-85°C for 1-3 hours to obtain the potted pulse capacitor module.

[0043] The potting primer is composed of the following raw materials in parts by weight: 80 parts methyl ethyl ether, 20 parts xylene, 18 parts vinyl silicone oil, 3 parts platinum catalyst, 10 parts hydrogen-containing silicone oil, and 2 parts tetramethyltetravinylcyclotetrasiloxane. By limiting the raw material composition of the potting primer, it can serve as a bonding medium between the potting adhesive and other interface materials, and can significantly improve the adhesion to substrates such as metals, conveyors, and PCBs.

[0044] When the plasma treatment equipment processes the potting shell 1 and the capacitor module 2, the plasma glow energy formed by oxygen and argon reacts with the molecular chains on the material surface, introducing oxygen-containing polar groups (such as hydroxyl -OH and carboxyl -COOH). These polar groups act like countless tiny "chemical hooks," forming strong chemical bonds with the potting adhesive molecules, firmly connecting the two materials together at the molecular level. Example 1

[0045] The method for fabricating a potted pulse capacitor module specifically includes the following steps:

[0046] Step 1: Use an air gun to clean the inner wall of the potting shell 1 and the welded capacitor module 2;

[0047] Step 2: The cleaned potting shell 1 and capacitor module 2 are sent into the cavity of the plasma treatment equipment. The plasma treatment equipment is evacuated to 50pa and the power of the plasma treatment equipment is adjusted to 300W. The mixed gas of oxygen and argon forms a luminous plasma glow, which is used to treat the potting shell 1 and capacitor module 2 for 5 minutes.

[0048] Step 3: After the process is completed, remove the potting shell 1 and the capacitor module 2 from the plasma equipment, and apply a potting primer to the inner wall of the potting shell 1 within 2 hours. When applying the primer, first fill the potting shell 1 with the potting primer, let it stand for 10 minutes and then pour it out. Then use a brush to smooth the inner wall of the potting shell 1.

[0049] Step 4: Place the potting shell 1 coated with potting primer into an oven and cure at 80°C for 15 minutes;

[0050] Step 5: Install the plasma-treated capacitor module 2 into the potting shell 1. First, fill it with one-third of the potting adhesive, then place the whole unit into a vacuum device and evacuate it to 0.1 MPa for 5 minutes. Then fill it with another one-third of the potting adhesive, and place the whole unit into a vacuum device and evacuate it to 0.1 MPa for 5 minutes. Repeat this process until the potting adhesive is full.

[0051] Step 6: Place the potting shell 1 filled with potting adhesive at 25°C for 3 hours to complete the initial curing; then put it into an oven and cure it at 80°C for 2 hours to obtain the potted pulse capacitor module.

[0052] Comparative Example 1

[0053] Its preparation method and structural composition are basically the same as those in Example 1. The main difference is that the inner wall of the potting shell 1 is not provided with grooves 11.

[0054] Comparative Example 2

[0055] Its preparation method and structural composition are basically the same as those in Example 1. The main difference is that in step 5, the plasma-treated capacitor module 2 is installed into the potting shell 1 and then filled with potting glue.

[0056] Comparative Example 3

[0057] Its preparation method and structural composition are basically the same as those in Example 1. The main difference is that steps 1, 2, 3 and 4 are not included. The welded capacitor module 2 is directly installed into the potting shell 1.

[0058] Temperature shock tests were conducted on the potted pulse capacitor modules prepared in Example 1 and Comparative Examples 1-3. For specific results, please refer to... Figures 3 to 6 The temperature shock test conditions are as follows: the sample is placed in a -55℃ low-temperature chamber for 30 minutes, then transferred to a 125℃ high-temperature chamber for 30 minutes, and then transferred from the high-temperature chamber to the low-temperature chamber within 5 minutes. This process is repeated 10 times. Figure 3 This is a sample image after testing in Example 1. Figure 4 This is a sample image after testing in Comparative Example 1. Figure 5 This is a sample image after testing in Comparative Example 2. Figure 6 This is a sample image after testing in Comparative Example 3.

[0059] pass Figures 3 to 6 As shown, Figure 3 The image shows a sample tested in Example 1. From the appearance, the color of the joint between the potting compound layer 3 and the potting shell 1 is uniform, indicating that there are no pores at the joint between the potting compound layer 3 and the potting shell 1. Figure 4 The image shows the sample after testing in Comparative Example 1. From the appearance, the color of the connection between the potting compound layer 3 and the potting shell 1 is different, indicating that there are pores at the connection between the potting compound layer 3 and the potting shell 1. Figure 5 The image shows the sample after testing in Comparative Example 2. From the appearance, the color of the connection between the potting compound layer 3 and the potting shell 1 is different, indicating that there are pores at the connection between the potting compound layer 3 and the potting shell 1. Figure 6 The image shows the sample after testing in Comparative Example 3. Visually, the color of the joint between the potting compound layer 3 and the potting shell 1 is uneven, indicating that there are pores at the joint between the potting compound layer 3 and the potting shell 1.

[0060] This application defines the structure of the potted pulse capacitor module, sets grooves 11 on the inner wall of the potting shell 1, and specifically defines the preparation method of the potted pulse capacitor module. The potting shell 1 and the capacitor module 2 are first treated by plasma glow discharge. Then, a potting primer is coated on the inner wall of the potting shell 1 as an adhesive medium. Then, the potting adhesive is repeatedly poured in and vacuumed multiple times to make the interior of the potted product dense and without pores. This ensures the structural strength of the prepared product and allows it to be used in high impact and vibration environments, meeting the usage requirements of the potted pulse capacitor module.

[0061] The above description is merely a preferred embodiment of the present invention and should not be construed as limiting the scope of the present invention. All equivalent changes and modifications made in accordance with the scope of the present invention and the contents of the specification should still fall within the scope of the present invention.

Claims

1. A method for preparing a potted pulse capacitor module, characterized in that: The potting pulse capacitor module includes a potting shell, a capacitor module disposed in the potting shell, and a potting adhesive layer filling the potting shell to fix the capacitor module. The inner wall of the potting shell is provided with a plurality of grooves, which are spaced apart along the vertical direction on the inner wall of the potting shell. The method for preparing the encapsulated pulse capacitor module specifically includes the following steps: Step 1: Use an air gun to clean the inner wall of the potting shell and the welded capacitor module; Step 2: The cleaned potting shell and capacitor module are sent into the cavity of the plasma treatment equipment. The plasma treatment equipment is evacuated to 50pa and the power of the plasma treatment equipment is adjusted to 200-400W. The mixed gas of oxygen and argon forms a luminous plasma glow, which is used to treat the potting shell and capacitor module for 3-8 minutes. Step 3: After the process is completed, remove the potting shell and capacitor module from the plasma equipment, and apply potting primer to the inner wall of the potting shell within 2 hours. When applying, first fill the plastic-sealed shell with potting primer, let it stand for 8-15 minutes and then pour it out. Then use a brush to smooth the inner wall of the potting shell. Step 4: Place the potting shell coated with potting primer into an oven and cure at 70-90℃ for 10-20 minutes. Step 5: Assemble the plasma-treated capacitor mold into the potting shell, first fill it with one-third of the potting adhesive, then put the whole thing into the vacuum equipment and evacuate for 4-6 minutes; then fill it with another one-third of the potting adhesive, and put the whole thing into the vacuum equipment and evacuate for 4-6 minutes again, repeating this process until the potting adhesive is full. Step 6: Place the potting shell filled with potting adhesive at 25°C for 2-4 hours to complete the initial curing; then put it into an oven and cure it at 75-85°C for 1-3 hours to obtain the potted pulse capacitor module.

2. The method for preparing a potted pulse capacitor module according to claim 1, characterized in that: The capacitor module includes two lead frames arranged opposite each other, a plurality of capacitor chip groups spaced apart between the two lead frames, and two solder layers respectively disposed inside the two lead frames. The capacitor chip group includes a plurality of capacitor chips stacked sequentially in a vertical direction, and the ends of the capacitor chips are connected to the opposite solder layers.

3. The method for preparing a potted pulse capacitor module according to claim 2, characterized in that: The lead frame includes a frame body, two connecting pins disposed opposite to the upper end of the frame body, and a plurality of vent holes spaced apart on the frame body. The connecting pins extend outward to the outside of the potting compound layer, and the plurality of vent holes are opposite to the ends of the capacitor chip.

4. The method for preparing a potted pulse capacitor module according to claim 3, characterized in that: The top of the potting housing has a downwardly extending positioning groove for the insertion of the relative connection pins.

5. The method for preparing a potted pulse capacitor module according to claim 4, characterized in that: The connection pin includes a connection segment connected to the upper end of the frame body and a pin segment arranged perpendicularly to the connection segment, the pin segment being embedded in a relative positioning groove.

6. The method for preparing a potted pulse capacitor module according to claim 5, characterized in that: The pin segment is provided with a connection hole.

7. The method for preparing a potted pulse capacitor module according to claim 2, characterized in that: The top of the capacitor chip assembly is lower than the top of the potting casing.

8. The method for preparing a potted pulse capacitor module according to claim 1, characterized in that: The groove extends outward from the inner wall of the potting shell, and its extension depth is 1-2 mm.

9. The method for preparing a potted pulse capacitor module according to claim 1, characterized in that: In step 5, the vacuum equipment is evacuated to 0.1 MPa.

10. The method for preparing a potted pulse capacitor module according to claim 1, characterized in that: In step 2, the volume ratio of oxygen to argon is 6:4.

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