Capacitor packaging structure and thin film capacitor

Abstract

The invention discloses a capacitor packaging structure and a thin film capacitor, and relates to the technical field of capacitors. The LED packaging structure comprises a packaging base, the upper surface of the packaging base is provided with an insulating base layer, the lower surface of the packaging base is provided with a plurality of shunting heat dissipation fin sets, and the packaging base and the insulating base layer are provided with corresponding through holes; the plurality of heat-conducting positioning pieces are used for positioning the core body and preventing the core body from shifting in the subsequent process or vibration, meanwhile, the heat-conducting positioning pieces serve as effective heat-conducting channels, heat of the core is conducted to the shell to be dissipated, and the heat can be dissipated to the lower heat-dissipating fin group through the base and can also be dissipated to the lower heat-dissipating fin group through the flow-dividing heat-dissipating fin group in cooperation with the ceramic column and the flow-dividing heat-dissipating fin group on the bottom side. By means of the double-path heat dissipation mode of the bottom and the side direction, the effective heat dissipation area is greatly increased, the bottleneck that traditional packaging mainly depends on pouring sealant to conduct heat is single and high in heat resistance is broken through, the heat of the core can be rapidly dissipated to the surrounding environment, and the core temperature rise is effectively reduced.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of capacitors, in particular to a capacitor packaging structure and a film capacitor. BACKGROUND

[0002] The film capacitor is a kind of capacitor made of an organic plastic film as a dielectric and a metal foil or a metalized film as an electrode through a winding method, and is widely used in the fields of power electronics, new energy and industrial control. With the continuous increase of the power density of electronic equipment, the film capacitor often needs to operate under high frequency and large current conditions, and the heat generated during operation is significantly increased, which puts higher requirements on the heat dissipation capacity of the packaging structure.

[0003] At present, the traditional film capacitor packaging structure is filled with potting glue in the shell to realize insulation and protection, and the heat dissipation path is relatively single, mainly relying on the heat conduction of the potting glue and the convective heat exchange of the shell surface. The overall thermal resistance is large, which leads to high temperature rise of the core, not only affecting the stability of the electrical performance, but also limiting the service life and reliability of the capacitor. In addition, before the potting process, the capacitor core is in an unfixed state in the shell, lacking effective mechanical positioning and guiding structure, which is easy to displace due to vibration or impact, not only causing the dispersion of electrical parameters (such as equivalent series inductance) to increase, but also possibly leading to lead loosening or even breaking, which seriously affects the product consistency and application safety. Therefore, the application provides a capacitor packaging structure and a film capacitor. SUMMARY

[0004] The purpose of the application is to solve the problems in the background art, and the application provides a capacitor packaging structure and a film capacitor.

[0005] In order to achieve the above purpose, the application specifically adopts the following technical scheme: One of the purposes of the application is to provide a capacitor packaging structure, which comprises: A packaging base, the upper surface of which is provided with an insulating base layer, and the lower surface is provided with a plurality of shunt heat dissipation fin groups, the packaging base and the insulating base layer are provided with corresponding through holes, and a plurality of vertical ceramic columns are embedded in the insulating base layer, one end of the ceramic column is connected with the packaging base, and the other end extends to the upper surface of the insulating base layer. A packaging shell, which is combined with the packaging base and jointly enclosed to form a sealed cavity, the inner wall of the packaging shell is provided with a plurality of annular heat conduction positioning members, which are used for positioning and heat conduction of the core, and the sealed cavity is filled with potting glue.

[0006] Further, the heat conduction positioning member comprises a heat conduction plate penetrating through the packaging shell, one end of the heat conduction plate located in the packaging shell is fixedly provided with a ceramic plate, one end of the ceramic plate is provided with a bending part, and the other end is provided with a guide inclined surface.

[0007] Further, a plurality of pipe grooves are formed through the array of the heat-conducting plate, and heat pipes are inserted into the pipe grooves, with one end of the heat pipes abutting against the ceramic plate.

[0008] Further, a plurality of cavities are formed in a section of the array of the heat-conducting plate in the encapsulation shell, and the cavities allow the heat-conducting plate to elastically deform to absorb the stress caused by thermal expansion and contraction of the encapsulation glue.

[0009] Further, the shunt heat dissipation fin group comprises longitudinal main fins arranged on the encapsulation base, and lateral auxiliary fins are arranged on both sides of the longitudinal main fins, and the longitudinal main fins and the lateral auxiliary fins are communicated with a filling cavity filled with heat-conducting silicone grease.

[0010] 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.

[0011] Further, the upper surface of the encapsulation base is provided with a surrounding barrier, and the surrounding barrier is inserted and matched with the encapsulation shell, and the inner wall of the encapsulation shell and the outer wall of the surrounding barrier are both provided with annular embedding grooves, and sealing rings are embedded in the two annular embedding grooves.

[0012] Further, the inner wall of the encapsulation shell is provided with an annular clamping groove, and a memory alloy ring is fixedly arranged on the surrounding barrier and clamped in the annular clamping groove.

[0013] Further, the encapsulation glue takes a paraffin-based phase change material as a matrix, and surface-modified boron nitride nanosheets are dispersed in the matrix.

[0014] The second object of the present application provides a thin film capacitor comprising the above-mentioned capacitor encapsulation 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 through the through holes at the ends.

[0015] The beneficial effects of the present application are as follows: 1. In the present application, the plurality of heat-conducting positioning members not only serve to position the core to prevent displacement of the core in subsequent processes or vibrations, but also serve as effective heat conduction channels to conduct heat from the core to the shell for dissipation. In combination with the ceramic columns on the bottom side and the shunt heat dissipation fin group, heat can be dissipated downward to the heat dissipation fin group on the bottom side or laterally to the shell through the heat-conducting positioning members. This double-path heat dissipation mode of the bottom side and the lateral side greatly increases the effective heat dissipation area, breaks through the single and high thermal resistance bottleneck of the traditional encapsulation which mainly relies on the encapsulation glue for heat conduction, and quickly dissipates the heat from the core to the surrounding environment, effectively reducing the core temperature rise.

[0016] 2、In the application, a pipe groove is formed in the heat-conducting plate, and a heat pipe is inserted in the pipe groove and overlaps the ceramic plate, so that a large amount of heat can be quickly transferred at a very small temperature difference, and the heat-conducting capacity is far higher than that of metal, which can effectively lead the heat of the core out, thereby further improving the heat dissipation effect of the capacitor. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a perspective view of the packaging structure of the application; Figure 2 is a perspective view of the packaging structure of the application; Figure 3 is another perspective view of the packaging structure of the application; Figure 4 is a perspective view of the shunt heat dissipation fin group of the application; Figure 5 is a perspective view of the shunt heat dissipation fin group of the application; Figure 6 is a perspective view of the shunt heat dissipation fin group of the application; Figure 2 is an enlarged view of A in the application; Figure 7 is an enlarged view of B in the application; Figure 2 Figure 8 is a perspective view of the thin-film capacitor of the application; Figure 9 is a perspective view of the thin-film capacitor of the application; Figure 10 is a perspective view of the capacitor core of the application.

[0018] Reference signs: 1, packaging base; 2, insulating base layer; 3, shunt heat dissipation fin group; 4, ceramic column; 5, packaging shell; 6, heat-conducting positioning piece; 7, potting adhesive; 8, through hole; 9, pipe groove; 10, heat pipe; 11, cavity; 12, bump; 13, fence; 14, annular embedding groove; 15, sealing ring; 16, annular clamping groove; 17, memory alloy ring; 18, capacitor core; 301, longitudinal main fin; 302, transverse auxiliary fin; 303, filling cavity; 304, heat-conducting silicone grease; 601, heat-conducting plate; 602, ceramic plate; 603, bending part; 604, guide slope; 1801, positive electrode conductive foil; 1802, negative electrode conductive foil; 1803, thin film; 1804, pin. DETAILED DESCRIPTION

[0019] To make the purpose, technical scheme and advantages of the embodiments of the application clearer, the technical scheme in the embodiments of the application will be described clearly and completely below with reference to the drawings in the embodiments of the application.

[0020] As Figures 1-7 ​As shown, the capacitor packaging structure provided by one embodiment of the present application comprises: The packaging base 1 is provided with an insulating base layer 2 on its upper surface and a plurality of shunt heat dissipation fin groups 3 on its lower surface, the packaging base 1 and the insulating base layer 2 are provided with corresponding through holes 8, the insulating base layer 2 is embedded with a plurality of vertical ceramic columns 4, 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, the lead wire passes through the through hole 8, the packaging base 1 is made of metal (for example, aluminum), the insulating base layer 2 is used for insulation, the ceramic column 4 is made of aluminum oxide ceramic material and has high thermal conductivity, the embedded ceramic column 4 provides reliable vertical support and high-strength insulation for the lead wire to prevent short circuit, on the other hand, the aluminum oxide ceramic itself has good thermal conductivity, part of the joule heat generated on the lead wire is conducted out through the packaging base 1 and then dissipated through the plurality of shunt heat dissipation fin groups 3, thereby establishing a high-efficiency heat dissipation path from the bottom. The packaging shell 5 is engaged with the packaging base 1 and jointly enclosed to form a sealed cavity, preferably, the packaging shell 5 is made of metal (for example, aluminum), after being engaged with the packaging base 1, the packaging shell 5 forms a packaging shell, the core is located in the packaging shell, the inner wall of the packaging shell 5 is provided with a plurality of annular heat-conducting positioning members 6, which are used for positioning and conducting heat, the sealed cavity is filled with potting glue 7, by arranging a plurality of annular heat-conducting positioning members 6 on the inner wall of the packaging shell 5, when the core is installed, the core is inserted in the center of the plurality of heat-conducting positioning members 6, the heat-conducting positioning member 6 simultaneously assumes the functions of positioning and heat conduction, before potting, it can accurately fix the core to prevent it from being displaced 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 wire 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 in the gap between the core and the packaging shell 5, thereby wrapping the core, while realizing the traditional insulation, moisture-proof and mechanical cushioning, it cooperates with the entire heat dissipation system to fill all the gaps to ensure that the heat can be efficiently transferred from the core to each heat dissipation component. In the present scheme, the plurality of heat-conducting positioning members 6 not only position the core to prevent it from being displaced 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 and the shunt heat dissipation fin group 3 on the bottom side, the heat can be dissipated to the heat dissipation fin group 3 downward through the base or conducted to the shell laterally through the heat-conducting positioning member 6, this double-path heat dissipation mode of the bottom plus the lateral greatly increases the effective heat dissipation area, breaks through the single high-thermal-resistance bottleneck of the traditional packaging which mainly relies on the potting glue 7 for heat conduction, and can quickly dissipate the heat of the core to the surrounding environment to effectively reduce the core temperature rise.

[0021] As Figure 2 and Figure 6 shown, the specific structure of the heat-conducting positioning member 6 of the application is disclosed, the heat-conducting positioning member 6 comprises a heat-conducting plate 601 fixedly penetrating the packaging shell 5, the heat-conducting plate 601 is fixedly provided with a ceramic plate 602 at one end inside the packaging shell 5, one end of the ceramic plate 602 is configured with a bending portion 603, and the other end is configured with a guide inclined surface 604, 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 shell 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 shell 5, thereby improving 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 out through the ceramic plate 602 and the heat-conducting plate 601, and can also play an insulation protection role, the guide inclined surface 604 makes the installation of the core smooth and easy, and avoids 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, thereby preventing the core from moving, and effectively positioning the core.

[0022] As Figure 6 shown, the further technical scheme of the heat-conducting plate 601 of the application is 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 the heat pipe 10 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) inside, one end of the heat pipe 10 in abutment with the ceramic plate 602 is an evaporation section, one end of the heat pipe 10 located outside the packaging shell 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 shell 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, and the cycle is completed, the working principle is based on phase change heat transfer and capillary action, can quickly transfer a large amount of heat under a very small temperature difference, and the heat conduction capacity is far superior to metal, which can effectively conduct the heat of the core, thereby further improving the heat dissipation effect of the capacitor.

[0023] As Figure 6As shown, a further technical solution of the present invention for the heat-conducting plate 601 is disclosed. A segment of the heat-conducting plate 601 located within the encapsulation shell 5 has several cavities 11. The cavities 11 allow the heat-conducting plate 601 to undergo elastic deformation to absorb stress caused by the thermal expansion and contraction of the potting compound 7. Preferably, the cavities 11 are circular or elliptical to avoid stress concentration. In actual processing, the heat-conducting plate 601 can be made of two plates, each with two half-cavities stamped on it, and then the two plates are joined together and brazed to form a complete cavity 11. The cavity 11 is designed so that the heat-conducting plate 601, made of a high thermal conductivity aluminum alloy such as 6063 aluminum alloy, has recoverable elastic deformation. When the cured potting compound 7 is heated and expands in volume, it cannot expand freely outward due to the constraint of the sturdy metal shell and base, thus generating huge compressive stress inside. The cavity 11 allows the heat-conducting plate 601 to undergo slight elastic deformation, absorbing and releasing these stresses like a spring, effectively preventing the potting compound 7 from delaminating from the shell or cracking itself, and ensuring the long-term sealing and heat dissipation stability of the encapsulation structure.

[0024] like Figure 4 and Figure 5 As shown, the specific structure of the heat dissipation fin assembly 3 of the present invention is disclosed. The heat dissipation fin assembly 3 includes a longitudinal main fin 301 disposed on the packaging base 1. Transverse auxiliary fins 302 are arrayed and connected to both sides of the longitudinal main fin 301. 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 thermally conductive silicone grease 304. The design of the longitudinal main fin 301 and the transverse auxiliary fins 302 can guide heat to multiple fins and dissipate it in parallel, avoiding heat accumulation. It maximizes the surface area in contact with air in a limited space, significantly improving the convective heat transfer efficiency. By filling the filling cavity 303 with thermally conductive silicone grease 304, the contact thermal resistance from the packaging base 1 to the root of the fin is greatly reduced, so that heat can be transferred to the end of the fin more efficiently, further improving the heat dissipation performance.

[0025] like Figure 6As shown, the present invention discloses a further technical solution for the ceramic pillar 4. The matrix of the insulating base layer 2 is silicone rubber. The ceramic pillar 4 has a number of micro-protrusions 12 arrayed above the upper surface of the insulating base layer 2. The insulating base layer 2 is made of silicone rubber, which not only has good insulation properties, but also provides excellent flexibility and adhesion, and can better adapt to the thermal expansion of different materials. Since the ceramic pillar 4 is embedded in it, its flexibility does not affect the support strength of the core. The arrayed micro-protrusions 12 on the ceramic pillar 4 minimize the contact area between the ceramic pillar 4 and the core while ensuring support and insulation, thereby reducing the mechanical stress concentration points. At the same time, it is equivalent to establishing multiple efficient point-to-point heat conduction channels on the main heat conduction path, which greatly reduces the interface thermal resistance and ensures that heat can flow from the core to the highly thermally conductive ceramic pillar 4 without obstruction, further improving the heat dissipation efficiency.

[0026] like Figure 6 and Figure 7 As shown, a further technical solution for the encapsulation base 1 is disclosed in this invention. The upper surface of the encapsulation base 1 is constructed with a barrier 13, which is inserted into the encapsulation shell 5. Both the inner wall of the encapsulation shell 5 and the outer wall of the barrier 13 are provided with annular grooves 14. Sealing rings 15 are embedded in the two annular grooves 14. By constructing a barrier 13 on the encapsulation base 1 that is inserted into the encapsulation shell 5, the contact area between the encapsulation base 1 and the encapsulation shell 5 is increased, making the subsequent welding or other fixing methods more stable. By opening the annular grooves 14 and embedding the sealing rings 15 in the annular grooves 14, the sealing effect is improved, thereby improving the overall encapsulation effect.

[0027] like Figure 7 As shown, the present invention discloses a further technical solution for the encapsulation housing 5. The inner wall of the encapsulation housing 5 is provided with an annular groove 16, and a shape memory alloy ring 17 is fixed on the enclosure 13 to engage with the annular groove 16. Utilizing the characteristics of the shape memory alloy ring 17, it is soft at low temperatures and can be inserted into the annular groove 16 under a certain deformation. When the internal temperature rises due to operation, the shape memory alloy restores its shape and generates a greater clamping force, which perfectly compensates for the problem of decreased high-temperature sealing performance that may be caused by the different thermal expansion rates of different materials, and further improves its encapsulation sealing effect.

[0028] like Figure 2As shown, the present invention discloses a further technical solution for potting compound 7. Potting compound 7 uses paraffin-based phase change material as a matrix, in which surface-modified boron nitride nanosheets are dispersed. When the temperature of the capacitor core rises sharply due to a sudden increase in instantaneous power, the paraffin absorbs a large amount of heat and melts (absorbs latent heat), preventing the temperature from rising sharply and protecting the core from thermal shock. When the power decreases and the temperature drops, the paraffin solidifies and releases heat, delaying the temperature drop. This greatly suppresses the fluctuation of the working temperature and improves the product's lifespan and reliability. The boron nitride nanosheets themselves are top-level insulating and thermally conductive materials. Their two-dimensional sheet structure can overlap with each other in the matrix to form an efficient phonon transport network (i.e., a heat conduction path), which greatly improves the overall thermal conductivity of the potting compound. This allows the potting compound 7 to have both active heat absorption and passive heat conduction capabilities, thereby further improving the heat dissipation efficiency of the capacitor.

[0029] like Figures 8-10 As shown, an embodiment of the present invention proposes a thin-film capacitor, including the above-described capacitor encapsulation structure, and further including a capacitor core 18 disposed within a sealed cavity. 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 leads 1804 with through holes 8 at their ends. Preferably, the thin film 1803 is one of polypropylene film, polyester film (PET), polyphenylene ether film (PPS), and polycarbonate film (PC), etc. Figure 10 As shown, two thin films 1803 are interleaved with positive conductive foil 1801 and negative conductive foil 1802 and then wound into a cylindrical shape. Together with two leads 1804, they form a capacitor core 18, which is then assembled into a sealed cavity formed by the encapsulation base 1 and the encapsulation shell 5. Finally, potting compound 7 is injected to form a thin film capacitor.

[0030] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded 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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