Capacitor package structure and thin film capacitor

Abstract

The application discloses a capacitor packaging structure and a thin film capacitor and relates to the technical field of capacitors; the application comprises a packaging base, an upper surface of the packaging base is provided with an insulating base layer, a lower surface of the packaging base is provided with a plurality of shunt heat dissipation fin groups, corresponding through holes are formed in the packaging base and the insulating base layer; a plurality of heat conduction positioning members are not only used for positioning the core body and preventing the core body from being displaced in subsequent processes or vibration, but also become effective heat conduction channels, heat of the core body is conducted to the shell for dissipation, the ceramic column on the bottom side and the shunt heat dissipation fin group are matched, heat can be dissipated to the heat dissipation fin group below through the base and can be conducted to the sleeve shell on the side through the heat conduction positioning member, the double-path heat dissipation mode of the bottom plus the side greatly increases the effective heat dissipation area, breaks through the single high-thermal-resistance bottleneck of the traditional packaging which mainly depends on the pouring glue for heat conduction, and can quickly dissipate the heat of the core body to the surrounding environment, so that the core temperature rise is effectively reduced.

Description

Technical Field

[0001] This invention relates to the field of capacitor technology, specifically to capacitor packaging structures and thin-film capacitors. Background Technology

[0002] Film capacitors are a type of capacitor made by winding organic plastic film as dielectric and metal foil or metallized film as electrodes. They are widely used in power electronics, new energy and industrial control. With the continuous increase in power density of electronic devices, film capacitors often need to operate under high frequency and high current conditions, which significantly increases the heat generated during operation and puts forward higher requirements for the heat dissipation capacity of the packaging structure.

[0003] Currently, traditional film capacitor packaging structures mostly use potting compound to fill the inside of the shell for insulation and protection. Their heat dissipation path is relatively simple, mainly relying on the heat conduction of the potting compound and the convection heat transfer on the surface of the shell. The overall thermal resistance is relatively large, resulting in excessive temperature rise of the core. This not only affects the stability of electrical performance, but also limits the service life and reliability of the capacitor. In addition, before the potting process, the capacitor core is in an unfixed state inside the shell, lacking an effective mechanical positioning and guiding structure. It is prone to displacement due to vibration or impact, which not only increases the dispersion of electrical parameters (such as equivalent series inductance), but may also cause the leads to loosening or even breakage, seriously affecting product consistency and application safety. Therefore, this invention proposes a capacitor packaging structure and a film capacitor. Summary of the Invention

[0004] The purpose of this invention is to address the problems mentioned above in the background art by providing a capacitor packaging structure and a thin-film capacitor.

[0005] To achieve the above objectives, the present invention specifically adopts the following technical solution:

[0006] One of the objectives of this invention is to provide a capacitor packaging structure comprising:

[0007] The encapsulation base has an insulating base layer on its upper surface and several shunt heat dissipation fins on its lower surface. Corresponding through holes are opened on the encapsulation base and the insulating base layer. Several vertically penetrating ceramic pillars are embedded in the insulating base layer. One end of the ceramic pillar is connected to the encapsulation base, and the other end extends to the upper surface of the insulating base layer.

[0008] The encapsulation shell, which is joined with the encapsulation base to form a sealed cavity, has several annularly distributed heat-conducting positioning elements on its inner wall for positioning and heat conduction of the core, and the sealed cavity is filled with potting compound.

[0009] Further, the heat-conducting positioning member comprises a heat-conducting plate penetrating the packaging shell, and a ceramic plate is fixedly arranged at one end of the heat-conducting plate in the packaging shell, and the ceramic plate is provided with a bending portion at one end and a guide inclined surface at the other end.

[0010] Further, a plurality of pipe grooves are arranged on the heat-conducting plate, and a heat pipe is inserted into the pipe grooves, and one end of the heat pipe is in abutting contact with the ceramic plate.

[0011] Further, a plurality of cavities are arranged on the heat-conducting plate in the packaging shell, and the cavities allow the heat-conducting plate to elastically deform to absorb the stress caused by thermal expansion and contraction of the pouring glue.

[0012] Further, the shunt heat dissipation fin group comprises longitudinal main fins arranged on the packaging base, and lateral auxiliary fins are arranged on both sides of the longitudinal main fins in an array, and the longitudinal main fins and the lateral auxiliary fins are communicated with a filling cavity, and the filling cavity is filled with heat-conducting silicone grease.

[0013] Further, the matrix of the insulating base layer is silicone rubber, and a plurality of micro-bumps are arranged on the upper surface of the insulating base layer in an array.

[0014] Further, the upper surface of the packaging base is provided with a surrounding barrier, and the surrounding barrier is inserted and matched with the packaging shell, and the inner wall of the packaging shell and the outer wall of the surrounding barrier are both provided with an annular embedding groove, and a sealing ring is embedded in the two annular embedding grooves.

[0015] Further, the inner wall of the packaging shell is provided with an annular clamping groove, and a memory alloy ring is fixedly arranged on the surrounding barrier and is clamped and matched with the annular clamping groove.

[0016] Further, the pouring glue takes a paraffin-based phase change material as a matrix, and surface-modified boron nitride nanosheets are dispersed in the matrix.

[0017] The second object of the present application provides a thin film capacitor comprising the capacitor packaging structure, and further comprising a capacitor core arranged in the sealed cavity, wherein the capacitor core comprises interleaved positive and negative conductive foils and two thin films, and the positive and negative conductive foils are respectively connected with pins penetrating the through holes at the ends.

[0018] The beneficial effects of the present application are as follows:

[0019] 1、In the present application, several heat-conducting positioning members are not only used for positioning the core body to prevent it from moving in the subsequent process or vibration, but also become effective heat-conducting channels to conduct the heat of the core to the shell for dissipation. In combination with the ceramic columns on the bottom side and the shunt heat dissipation fin group, the heat can be dissipated downward to the heat dissipation fin group through the base, or conducted to the side shell through the heat-conducting positioning members. This double-path heat dissipation mode of bottom plus side greatly increases the effective heat dissipation area, breaks through the single high thermal resistance bottleneck of traditional packaging mainly relying on pouring glue for heat conduction, and can quickly dissipate the heat of the core to the surrounding environment, effectively reducing the core temperature rise.

[0020] 2、In the present application, a pipe groove is formed in the heat-conducting plate, and a heat pipe lapped with the ceramic plate is inserted in the pipe groove. The heat pipe can quickly transfer a large amount of heat under a very small temperature difference, and its heat conduction capacity far exceeds that of metal, which can effectively conduct the heat of the core body out, thereby further improving the heat dissipation effect of the capacitor. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is a perspective view of the packaging structure of the present application;

[0022] Figure 2 is a perspective view of the packaging structure of the present application;

[0023] Figure 3 is another perspective view of the packaging structure of the present application;

[0024] Figure 4 is a perspective view of the shunt heat dissipation fin group of the present application;

[0025] Figure 5 is a perspective view of the shunt heat dissipation fin group of the present application;

[0026] Figure 6 is an enlarged view of A in the present application; Figure 2

[0027] Figure 7 is an enlarged view of B in the present application; Figure 2

[0028] Figure 8 is a perspective view of the thin film capacitor of the present application;

[0029] Figure 9 is a perspective view of the thin film capacitor of the present application;

[0030] Figure 10 is a perspective view of the capacitor core of the present application.

[0031] ​​Fig. 1 is a packaging base; 2 is an insulating base layer; 3 is a shunt heat dissipation fin group; 4 is a ceramic column; 5 is a packaging shell; 6 is a heat-conducting positioning piece; 7 is potting glue; 8 is a through hole; 9 is a pipe groove; 10 is a heat pipe; 11 is a cavity; 12 is a bump; 13 is a fence; 14 is an annular embedding groove; 15 is a sealing ring; 16 is an annular clamping groove; 17 is a memory alloy ring; 18 is a capacitor core; 301 is a longitudinal main fin; 302 is a transverse auxiliary fin; 303 is a filling cavity; 304 is heat-conducting silicone grease; 601 is a heat-conducting plate; 602 is a ceramic plate; 603 is a bending part; 604 is a guide slope; 1801 is a positive electrode conductive foil; 1802 is a negative electrode conductive foil; 1803 is a film; 1804 is a pin. DETAILED DESCRIPTION

[0032] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application.

[0033] As shown in Figures 1-7 An embodiment of the capacitor packaging structure provided by the present application comprises:

[0034] The packaging base 1 is provided with an insulating base layer 2 on the upper surface and a plurality of shunt heat dissipation fin groups 3 on the lower surface. Corresponding through holes 8 are formed in the packaging base 1 and the insulating base layer 2. A plurality of vertical ceramic columns 4 are embedded in the insulating base layer 2. One end of the ceramic column 4 is connected to the packaging base 1, and the other end extends to the upper surface of the insulating base layer 2. In actual use, the core is mounted on the insulating base layer 2, and the lead is passed out through the through hole 8. The packaging base 1 is made of metal (for example, aluminum), and the insulating base layer 2 serves as an insulating function. The ceramic column 4 is made of aluminum oxide ceramic material, which has high thermal conductivity. The embedded ceramic column 4 provides reliable vertical support and high-strength insulation for the lead, preventing short circuits. On the other hand, the aluminum oxide ceramic itself has good thermal conductivity, which can conduct part of the joule heat generated on the pin out of the packaging base 1, and then dissipate heat through the plurality of shunt heat dissipation fin groups 3, thereby establishing a high-efficiency heat dissipation path from the bottom;

[0035] The packaging shell 5 is engaged with the packaging base 1 and jointly encloses a closed cavity. Preferably, the packaging shell 5 is made of metal (for example, aluminum), which is engaged with the packaging base 1 to form a packaging shell, and the core is located in the packaging shell. The inner wall of the packaging shell 5 is provided with a plurality of annularly distributed heat-conducting positioning members 6, which are used for positioning and heat conduction of the core. The closed cavity is filled with potting glue 7. By arranging a plurality of annularly distributed heat-conducting positioning members 6 on the inner wall of the packaging shell 5, when the core is installed, the core is inserted into the center of the plurality of heat-conducting positioning members 6. The heat-conducting positioning members 6 simultaneously undertake the functions of positioning and heat conduction. Before potting, it can accurately fix the core to prevent it from shifting in the subsequent process or vibration, thereby ensuring the consistency of the electrical parameters (such as inductance value) of the product and the reliability of the lead connection. In operation, it becomes an effective heat conduction channel to conduct the heat of the core to the shell for dissipation. After the core is positioned by the plurality of heat-conducting positioning members 6, the potting glue 7 is filled between the core and the packaging shell 5 to wrap the core, thereby achieving the functions of traditional insulation, moisture-proof, and mechanical cushioning, and cooperating with the entire heat dissipation system to fill all gaps and ensure efficient heat transfer from the core to various heat dissipation components.

[0036] In the present scheme, the plurality of heat-conducting positioning members 6 not only position the core to prevent it from shifting in the subsequent process or vibration, but also become an effective heat conduction channel to conduct the heat of the core to the shell for dissipation. In cooperation with the ceramic column 4 on the bottom side and the shunt heat dissipation fin group 3, the heat can be dissipated downward to the heat dissipation fin group 3 through the base, or can be conducted to the side shell through the heat-conducting positioning members 6. This double-path heat dissipation mode of the bottom plus the side greatly increases the effective heat dissipation area, breaks through the single, high-thermal-resistance bottleneck of traditional packaging which mainly relies on the potting glue 7 for heat conduction, and quickly dissipates the heat of the core to the surrounding environment, thereby effectively reducing the core temperature rise.

[0037] As Figure 2 and Figure 6As shown, the specific structure of the heat-conducting positioning member 6 is disclosed, the heat-conducting positioning member 6 comprises a heat-conducting plate 601 fixedly penetrating the packaging sleeve 5, the heat-conducting plate 601 is fixedly arranged with a ceramic plate 602 at one end in the packaging sleeve 5, the ceramic plate 602 is configured with a bending portion 603 at one end and a guide inclined surface 604 at the other end, preferably, the heat-conducting plate 601 adopts high-thermal-conductivity aluminum alloy, such as 6063 aluminum alloy, which takes into account excellent thermal conductivity and light weight, and is fixedly penetrated by the packaging sleeve 5, which can not only be used for positioning and heat conduction, but also can be used as a heat dissipation fin for the part protruding out of the packaging sleeve 5 to improve the heat dissipation efficiency, the ceramic plate 602 adopts alumina ceramic, which has high thermal conductivity and insulation, can effectively conduct the heat of the core through the ceramic plate 602 and the heat-conducting plate 601, and also can play an insulation protection role, the guide inclined surface 604 makes the installation of the core smooth and easy, avoiding damage, and the configuration of the bending portion 603 enables the bending portion 603 to clamp the core after the core is clamped between the plurality of heat-conducting plates 601, preventing the core from moving, thereby effectively positioning the core.

[0038] As shown in the figure, Figure 6 Further technical solutions of the heat-conducting plate 601 are disclosed, a plurality of pipe grooves 9 are arrayed and penetrated on the heat-conducting plate 601, a heat pipe 10 is inserted in the pipe groove 9, one end of the heat pipe 10 is in abutment with the ceramic plate 602, the pipe groove 9 is arranged on the heat-conducting plate 601, and the heat pipe 10 is inserted in the pipe groove 9, the heat pipe 10 adopts a copper pipe, both ends of which are closed, the heat pipe 10 is provided with a wick (composed of capillary porous material, responsible for providing capillary force required for liquid backflow) and working liquid (such as pure water, ammonia, liquid metal, etc., which transfers heat in the evaporation and condensation process), one end of the heat pipe 10 in abutment with the ceramic plate 602 is an evaporation section, and the other end of the heat pipe 10 located outside the packaging sleeve 5 is a condensation section, the heat of the core is conducted to the evaporation section of the heat pipe 10 through the ceramic plate 602, the evaporation section is heated, the working liquid absorbs heat and evaporates into steam, the steam flows to the condensation section under the driving of pressure difference, since the condensation section is located outside the packaging sleeve 5, the steam releases heat and condenses into liquid in the condensation section, and the condensed liquid backflows to the evaporation section under the capillary action of the wick, completing the cycle, the working principle is based on phase change heat transfer and capillary action, which can quickly transfer a large amount of heat under a very small temperature difference, and the heat conduction capacity far exceeds that of metal, which can effectively conduct the heat of the core, thereby further improving the heat dissipation effect of the capacitor.

[0039] As shown in the figure, Figure 6As shown in the figure, the further technical scheme of the application for the heat-conducting plate 601 is disclosed, a plurality of cavities 11 are arranged in a section of the array of the heat-conducting plate 601 in the packaging shell 5, the cavities 11 allow the heat-conducting plate 601 to produce elastic deformation to absorb the stress generated by the thermal expansion and contraction of the pouring glue 7, preferably, the cavities 11 are circular or elliptical in structure to avoid stress concentration, the heat-conducting plate 601 can adopt two plate bodies in actual processing, two cavities are punched in two plate bodies respectively, and then the two plate bodies are welded together to form a complete cavity 11, by arranging the cavities 11, since the heat-conducting plate 601 adopts high-thermal-conductivity aluminum alloy such as 6063 aluminum alloy, it has recoverable elastic deformation, when the pouring glue 7 after solidification is heated and expands in volume, but due to the constraint of the solid metal shell and the base, it cannot freely expand outward, thereby generating a huge compressive stress inside, the cavities 11 allow the heat-conducting plate 601 to produce slight elastic deformation, like a spring, to absorb and release these stresses, effectively preventing the pouring glue 7 from delaminating with the shell or cracking itself, and ensuring the long-term sealing performance and heat dissipation stability of the packaging structure.

[0040] As shown in the figure, Figure 4 and Figure 5 The specific structure of the shunt heat dissipation fin group 3 is disclosed, the shunt heat dissipation fin group 3 includes longitudinal main fins 301 arranged on the packaging base 1, transverse auxiliary fins 302 are arranged on both sides of the longitudinal main fins 301 in an array, the longitudinal main fins 301 and the transverse auxiliary fins 302 are communicated with filling cavities 303, the filling cavities 303 are filled with heat-conducting silicone grease 304, the design of the longitudinal main fins 301 and the transverse auxiliary fins 302 can guide heat to multiple fins and dissipate in parallel, avoiding heat accumulation, and maximizing the surface area in contact with air in a limited space, significantly improving the convective heat transfer efficiency, by filling the heat-conducting silicone grease 304 in the filling cavities 303, the contact thermal resistance from the packaging base 1 to the fin root is greatly reduced, so that heat can be more efficiently transmitted to the fin tip, further improving the heat dissipation performance.

[0041] As shown in the figure, Figure 6As shown in the figure, the further technical scheme of the application for the ceramic column 4 is disclosed, the matrix of the insulating base layer 2 is silicone rubber, and the ceramic column 4 is arranged with a plurality of micro-bumps 12 on the upper surface of the insulating base layer 2. The insulating base layer 2 adopts silicone rubber, which not only has good insulation, but also provides excellent flexibility and adhesion, and can better adapt to the thermal expansion of different materials. Since the ceramic column 4 is embedded, the flexibility does not affect the support strength of the core, the micro-bumps 12 are arranged on the ceramic column 4, the contact area between the ceramic column 4 and the core is minimized under the premise of ensuring support and insulation, thereby reducing the mechanical stress concentration point. At the same time, a plurality of efficient point-to-point heat conduction channels are established on the main heat conduction path, which greatly reduces the interface thermal resistance, ensures that heat can flow unobstructed from the core to the high-thermal-conductivity ceramic column 4, and further improves the heat dissipation efficiency.

[0042] As shown in the figure, Figure 6 and Figure 7 As shown in the figure, the further technical scheme of the application for the packaging base 1 is disclosed, the upper surface of the packaging base 1 is arranged with a fence 13, the fence 13 is inserted and matched with the packaging shell 5, the inner wall of the packaging shell 5 and the outer wall of the fence 13 are both provided with an annular embedding groove 14, and a sealing ring 15 is embedded in the two annular embedding grooves 14. By arranging the fence 13 on the packaging base 1 for inserting and matching with the packaging shell 5, the contact area between the packaging base 1 and the packaging shell 5 is increased, so that the subsequent welding or other fixing methods are more stable after being fixed. By providing the annular embedding groove 14 and embedding the sealing ring 15 in the annular embedding groove 14, the sealing effect is improved, thereby improving the overall packaging effect.

[0043] As shown in the figure, Figure 7 As shown in the figure, the further technical scheme of the application for the packaging shell 5 is disclosed, the inner wall of the packaging shell 5 is provided with an annular clamping groove 16, and a memory alloy ring 17 is fixedly arranged on the fence 13 and clamped in the annular clamping groove 16. By using the characteristics of the memory alloy ring 17, it is soft at low temperature and can be clamped into the annular clamping groove 16 under a certain deformation. When the internal temperature rises due to work, the memory alloy restores its shape and generates greater clamping force, perfectly compensating for the problem of decreased high-temperature sealing caused by different thermal expansion rates of different materials, and further improving the packaging and sealing effect.

[0044] As shown in the figure, Figure 2As shown, the further technical scheme of the invention for the pouring sealant 7 is disclosed, the pouring sealant 7 takes paraffin phase change material as a matrix, wherein the surface modified boron nitride nanosheet is dispersed, when the capacitor core temperature rises sharply due to the sudden power surge, the paraffin absorbs a large amount of heat and melts (absorbs latent heat), prevents the temperature from rising sharply, protects the core from thermal shock, when the power decreases and the temperature decreases, the paraffin solidifies and releases heat, delays the temperature drop, which greatly suppresses the working temperature fluctuation, improves the life and reliability of the product, the boron nitride nanosheet itself is a top-level insulating and heat-conducting material, its two-dimensional sheet structure can be overlapped in the matrix to form an efficient phonon transmission network (i.e. heat conduction path), greatly improving the overall thermal conductivity of the pouring sealant, so that the pouring sealant 7 has both active heat absorption and passive heat conduction capabilities, thereby further improving the heat dissipation efficiency of the capacitor.

[0045] As shown in the figure, Figures 8-10 An embodiment of the film capacitor provided by the present application comprises the capacitor packaging structure described above, and further comprises a capacitor core 18 arranged in the sealed cavity. The capacitor core 18 comprises interleaved winding positive conductive foil 1801, negative conductive foil 1802 and two films 1803. The positive conductive foil 1801 and the negative conductive foil 1802 are respectively connected with the pins 1804 penetrating through the through holes 8. Preferably, the film 1803 is made of one of polypropylene film, polyester film (PET), polyphenylene sulfide film (PPS) and polycarbonate film (PC), as shown in the figure. Figure 10 As shown in the figure, the two films 1803 are interleaved and wound with the positive conductive foil 1801 and the negative conductive foil 1802 to form a cylindrical shape, and cooperate with the two pins 1804 to form a capacitor core 18, which is assembled in the sealed cavity formed by the packaging base 1 and the packaging shell 5, and then the pouring sealant 7 is poured to form a film capacitor.

[0046] The above description of the disclosed embodiments enables a person skilled in the art to implement or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A capacitor packaging structure, characterized in that, include: The encapsulation base (1) has an insulating base layer (2) on its upper surface and several shunt heat dissipation fins (3) on its lower surface. The encapsulation base (1) and the insulating base layer (2) have corresponding through holes (8). Several vertically penetrating ceramic pillars (4) are embedded in the insulating base layer (2). One end of the ceramic pillar (4) is connected to the encapsulation base (1), and the other end extends to the upper surface of the insulating base layer (2). The matrix of the insulating base layer (2) is silicone rubber. Several micro-bumps (12) are arrayed above the upper surface of the insulating base layer (2). The encapsulation shell (5) is joined with the encapsulation base (1) to form a sealed cavity. The inner wall of the encapsulation shell (5) is provided with a number of annularly distributed heat-conducting positioning elements (6) for positioning the core and conducting heat. The sealed cavity is filled with potting compound (7). The heat-conducting positioning elements (6) include a heat-conducting plate (601) that is fixed through the encapsulation shell (5). A ceramic plate (602) is fixed at one end of the heat-conducting plate (601) inside the encapsulation shell (5). One end of the ceramic plate (602) is constructed with a bend (603), and the other end is constructed with a guide slope (604). The heat-conducting plate (601) is arrayed with through-holes. A plurality of tube grooves (9) are provided, and heat pipes (10) are inserted in the tube grooves (9). One end of the heat pipes (10) is in contact with the ceramic plate (602). The upper surface of the encapsulation base (1) is constructed with a baffle (13). The baffle (13) is inserted into the encapsulation shell (5). The inner wall of the encapsulation shell (5) and the outer wall of the baffle (13) are both provided with annular grooves (14). Sealing rings (15) are embedded in the two annular grooves (14). The inner wall of the encapsulation shell (5) is provided with annular slots (16). A shape memory alloy ring (17) is fixed on the baffle (13) and engages with the annular slots (16).

2. The capacitor packaging structure according to claim 1, characterized in that, The heat-conducting plate (601) is located in an array within the encapsulation housing (5) and has several cavities (11). The cavities (11) allow the heat-conducting plate (601) to undergo elastic deformation to absorb the stress caused by the thermal expansion and contraction of the potting compound (7).

3. The capacitor packaging structure according to claim 1, characterized in that, The heat dissipation fin assembly (3) includes a longitudinal main fin (301) disposed on the encapsulation base (1). Both sides of the longitudinal main fin (301) are connected in an array with transverse auxiliary fins (302). The longitudinal main fin (301) and the transverse auxiliary fins (302) are connected by a filling cavity (303). The filling cavity (303) is filled with thermal grease (304).

4. The capacitor packaging structure according to claim 1, characterized in that, The potting compound (7) uses paraffin-based phase change material as a matrix, in which surface-modified boron nitride nanosheets are dispersed.

5. A film capacitor, characterized in that, The capacitor encapsulation structure includes the capacitor core (18) disposed in a sealed cavity as described in any one of claims 1-4. The capacitor core (18) includes an alternatingly wound positive conductive foil (1801), a negative conductive foil (1802), and two thin films (1803). The positive conductive foil (1801) and the negative conductive foil (1802) are respectively connected to pins (1804) with end through holes (8).

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