High-power thin patch type bridge rectifier

Abstract

The invention relates to a high-power thin patch type bridge rectifier, which comprises an upper patch, a lower patch, four diode chips, an epoxy resin packaging body and four pins extending out of the epoxy resin packaging body, and a conical hole arranged along the thickness direction of the epoxy resin packaging body is formed in the middle of the epoxy resin packaging body in a penetrating manner; the four diode chips are distributed in a rhombus shape around the taper hole. The hole wall of the taper hole is provided with a heat dissipation fin set which is annularly arranged, four heat pipes are arranged in the epoxy resin packaging body, the evaporation section of each heat pipe is connected with one diode chip in a heat conduction mode, and the condensation section of each heat pipe extends to be fixedly welded to the heat dissipation fin set. According to the invention, the heat of the diode chip is rapidly transmitted to the heat dissipation fin group at the conical hole through the heat pipe, so that the density of air in the conical hole is reduced after the air is heated, the air naturally rises, and external cold air enters from the bottom of the conical hole for supplementation, thereby forming natural convective circulation. And a dual heat dissipation effect formed by temperature difference driving type active heat dissipation and passive heat dissipation of the heat pipe and the heat dissipation fin group is formed.

Description

Technical Field

[0001] This application relates to the technical field of semiconductor devices, and particularly to a high-power thin-type surface-mount bridge rectifier. Background Art

[0002] A surface-mount bridge rectifier is a rectifying device that adopts surface mount technology (SMT). Its core function is to convert alternating current into direct current, and it is suitable for high-power and high-density circuit scenarios. It features thinness, efficient heat dissipation, and high current-carrying capacity, with a typical thickness of only 1.4 - 1.6 mm. It mainly adopts an upper and lower surface-mount structure, in which four diode chips are soldered with solder paste, and the outside is encapsulated with epoxy resin and extends pins.

[0003] In the related technology, the Chinese patent application with the application number CN202010599497.9 proposed a high-power thin-type surface-mount bridge rectifier, including: a first diode chip, a second diode chip, a metal lead frame, and an L-shaped metal lead. A number of first protrusions are spaced apart on the surface of the first welding strip of the metal lead frame, and the first welding strip, the first protrusions, the positive electrodes of the first diode chip and the second diode chip are connected through a first solder layer; a number of second protrusions are spaced apart on the surface of the second welding strip of the L-shaped metal lead, and the second welding strip, the second protrusions, the negative electrodes of the first diode chip and the second diode chip are connected through a second solder layer; the areas of the first welding strip of the metal lead frame and the second welding strip of the L-shaped metal lead where they are located on the first diode chip and the second diode chip each have a convex portion protruding outward. This invention avoids false soldering through the design of the first protrusions and the second protrusions, improves the reliability of the device, effectively prevents water vapor from entering the device, and improves the weather resistance and overall strength.

[0004] The above-mentioned related technology has the following defects: The working current of a high-power thin-type surface-mount bridge rectifier can usually reach 8 A or more. Compared with the working current of 4 A of a conventional bridge rectifier, such a high-power rectifier has a greater demand for heat dissipation during operation. Currently, it mainly relies on copper sheets and encapsulated epoxy resin for passive heat conduction, and there is a certain upper limit to the heat dissipation efficiency. Once too much heat accumulates at the diode chip, it will still cause the diode chip to become unsoldered. Summary of the Invention

[0005] In order to improve the problem that it is difficult for a high-power surface-mount rectifier to meet the requirements by relying on passive heat dissipation of copper sheets and epoxy resin, this application provides a high-power thin-type surface-mount bridge rectifier.

[0006] A high-power thin-type surface-mount bridge rectifier provided by this application adopts the following technical solutions: A high-power thin-film surface-mounted bridge rectifier, comprising an upper patch, a lower patch, four diode chips, an epoxy resin encapsulation body, and four pins protruding from the epoxy resin encapsulation body. A tapered hole is provided through the middle of the epoxy resin encapsulation body along its thickness direction, and the four diode chips are distributed in a rhombus around the tapered hole; An annular heat dissipation fin group is installed on the wall of the tapered hole. Four heat pipes are arranged in the epoxy resin encapsulation body. The evaporation section of the heat pipe is thermally connected to one of the diode chips, and the condensation section extends to be welded and fixed to the heat dissipation fin group.

[0007] Furthermore, the upper patch includes a first upper copper sheet and a second upper copper sheet which are insulated from each other and respectively correspond to two of the diode chips. The lower patch includes a first lower copper sheet and a second lower copper sheet which are insulated from each other and respectively correspond to two diode chips; Two diode chips adjacent to the insulated parts of the first lower copper sheet and the second lower copper sheet correspond to the first upper copper sheet, and two diode chips adjacent to the other insulated parts of the first lower copper sheet and the second lower copper sheet correspond to the second upper copper sheet.

[0008] Furthermore, the parts of the first upper copper sheet and the second upper copper sheet corresponding to two opposite diode chips protrude downward with first protrusions, and the parts of the first lower copper sheet and the second lower copper sheet corresponding to the other pair of opposite diode chips protrude upward with second protrusions; The four diode chips include an upper chip and a lower chip which are arranged in a staggered manner in the vertical direction. The upper chip is located between the second protrusion and the first upper copper sheet or the second upper copper sheet, and the lower chip is located between the first protrusion and the first lower copper sheet or the second lower copper sheet.

[0009] Furthermore, the heat dissipation fin group includes two annular integral fins spaced along the axial direction of the tapered hole. The evaporation section of the heat pipe corresponding to the lower chip is located in the back groove of the corresponding first protrusion, and the condensation section is connected to the upper annular integral fin. The evaporation section of the heat pipe corresponding to the upper chip is located in the back groove of the corresponding second protrusion, and the condensation section is connected to the lower annular integral fin.

[0010] Furthermore, the condensation section of the heat pipe has a semi-circular arc portion adapted to the annular integral fin, and the semi-circular arc portion is located on the upper end surface of the annular integral fin.

[0011] Furthermore, the annular integral fin is inclined, and its inner edge end is closest to the upper end surface of the epoxy resin encapsulation body.

[0012] Furthermore, the heat dissipation fin group further includes a plurality of split fins that are circumferentially and equally spaced along the axial direction of the tapered hole. The split fins are arranged on one side of the lower annular integral fin close to the lower end face of the epoxy resin encapsulation body. A bimetallic strip is fixedly connected between the split fin and the hole wall of the tapered hole. The bimetallic strip is configured to drive the split fin to flip towards the annular integral fin when its body temperature is greater than a set value.

[0013] Furthermore, a honeycomb copper mesh ring is provided on the hole wall of the tapered hole between the bimetallic strip and the adjacent annular integral fin.

[0014] Furthermore, a plurality of spiral guide vanes are fixedly connected to the lower end face of the epoxy resin encapsulation body and are circumferentially and equally spaced along the axial direction of the tapered hole. The spiral guide vanes are arranged radially along the tapered hole, and the side of the spiral guide vane facing away from the epoxy resin encapsulation body is flush with the free end of the pin.

[0015] Furthermore, an insulating heat-conducting layer is provided between the contact portions of the heat pipe with the upper patch and the lower patch and / or between the contact portions of the heat pipe with the heat dissipation fin group.

[0016] In summary, the beneficial technical effects of this application are as follows: 1. By staggering the two upper chips and the two lower chips in the epoxy resin encapsulation body in the vertical direction, heat dissipation interference between the two diode chips on the same layer can be avoided, and staggered heat dissipation can be achieved between the two diode chips on the same side. The interference area between the heat dissipation spaces of each diode chip is extremely small, which helps the diode chips dissipate heat through the upper patch, the lower patch, and the epoxy resin encapsulation body, so as to improve the heat dissipation efficiency of the diode chips within an effective volume space. 2. The heat pipe quickly transfers the heat of the diode chip to the heat dissipation fin group at the tapered hole in the middle of the epoxy resin encapsulation body, causing the air in the tapered hole to be heated and its density to decrease, so it naturally rises, and the external cold air enters from the bottom of the tapered hole to supplement, forming a natural convection cycle; and due to the upper-small-lower-large setting of the tapered hole, the suction force on the bottom cold air can be enhanced, and the hot air can be quickly discharged from the tapered hole, forming a dual heat dissipation effect composed of active heat dissipation driven by temperature difference + passive heat dissipation of the heat pipe and the heat dissipation fin group, which can improve the hot air discharge efficiency. 3. Compared with ordinary straight holes, which have defects such as high air flow resistance, low flow rate, easy formation of "dead zones", and short air flow residence time, and are essentially passive heat dissipation; the setting of the tapered hole in this application can enhance the suction force on the bottom cold air, increase the air flow speed in the tapered hole to promote the rapid discharge of hot air, form an efficient cycle, so as to enhance the heat exchange effect between the cold air and the heat dissipation fin group, and the comprehensive heat dissipation efficiency is significantly improved. 4. By setting different angles of inclination, materials, and the number of ultra-thin fins for the upper and lower annular integral fins, the heat dissipation and cooling differences of the corresponding heat pipes caused by the different temperatures of the airflows in contact with the two annular integral fins can be reduced, ensuring the working stability and service life of the four diode chips; 5. By setting multiple split fins, bimetallic sheets, and honeycomb copper mesh rings, the angle of inclination of the split fins can be adjusted in real time according to the temperature at the root of the lower annular integral fin, and then the airflow concentration at the air inlet of the tapered hole can be adjusted to dynamically adjust the overall heat dissipation effect of the two annular integral fins. Description of the Drawings

[0017] Figure 1 is the overall structural schematic diagram of the embodiment of the present application; Figure 2 is the structural schematic diagram of the embodiment of the present application after the epoxy resin encapsulation body is removed; Figure 3 is the exploded structural schematic diagram of the embodiment of the present application after the epoxy resin encapsulation body is removed; Figure 4 is along Figure 1 the sectional structural schematic diagram taken along the line A-A in Figure 5 is along Figure 1 the sectional structural schematic diagram taken along the line B-B in Figure 6 is Figure 4 the partial enlarged schematic diagram of part C in Figure 7 is the structural schematic diagram of the embodiment of the present application mainly for showing the spiral guide fins.

[0018] Description of the Reference Numerals: 11. Upper patch; 111. First upper copper sheet; 112. Second upper copper sheet; 113. First convex part; 12. Lower patch; 121. First lower copper sheet; 122. Second lower copper sheet; 123. Second convex part; 2. Diode chip; 21. Upper chip; 22. Lower chip; 3. Epoxy resin encapsulation body; 31. Tapered hole; 4. Pin; 5. Heat pipe; 51. Semi-circular part; 61. Annular integral fin; 62. Split fin; 63. Bimetallic sheet; 64. Honeycomb copper mesh ring; 7. Spiral guide fin. Detailed Embodiment

[0019] The technical solution of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts shall fall within the scope of protection of the present application.

[0020] An embodiment of the present application discloses a high-power thin patch bridge rectifier. Referring to Figure 1 , Figure 2 and Figure 3 , it includes an upper patch 11, a lower patch 12, four diode chips 2, an epoxy resin encapsulation body 3, and four pins 4 extending out of the epoxy resin encapsulation body 3. A tapered hole 31 is formed through the middle of the epoxy resin encapsulation body 3 along its thickness direction, and the taper of the tapered hole 31 is 10° - 15°. The four diode chips 2 are distributed in a rhombus around the tapered hole 31. Among them, one side of the epoxy resin encapsulation body 3 close to the free end of the pin 4 is the lower end face, and the other side is the upper end face.

[0021] An annular heat dissipation fin group is installed on the wall of the tapered hole 31. Four heat pipes 5 are arranged in the epoxy resin encapsulation body 3. The evaporation section of the heat pipe 5 is thermally connected to one of the diode chips 2, and the condensation section extends to be welded and fixed to the heat dissipation fin group. Among them, the heat pipe 5 is a sintered copper heat pipe 5, its cross-section is rectangular and the whole is flat, and the internal working medium is water. The capillary effect of the internal capillary head is used to realize the reflux of the working medium between the condensation section and the evaporation section.

[0022] Specifically, the upper patch 11 includes a first upper copper sheet 111 and a second upper copper sheet 112 which are insulated from each other and respectively correspond to two diode chips 2. The lower patch 12 includes a first lower copper sheet 121 and a second lower copper sheet 122 which are insulated from each other and respectively correspond to two diode chips 2. The first upper copper sheet 111, the second upper copper sheet 112, the first lower copper sheet 121, and the second lower copper sheet 122 are all triangular as a whole, and an arc-shaped notch is provided at a position close to the tapered hole 31, so that the upper patch 11 and the lower patch 12 occupy as large an area as possible in the epoxy resin encapsulation body 3, and the good heat conduction effect of copper is used to achieve an efficient heat dissipation effect on the rectifier of the present application.

[0023] Among them, referring to Figure 2 and Figure 3, the two diode chips 2 on the first lower copper sheet 121 and the second lower copper sheet 122 adjacent to their insulating parts correspond to the first upper copper sheet 111, and the two diode chips 2 on the first lower copper sheet 121 and the second lower copper sheet 122 adjacent to their other insulating parts correspond to the second upper copper sheet 112. That is, the insulating part between the first upper copper sheet 111 and the second upper copper sheet 112 is arranged in a staggered manner with the insulating part between the first lower copper sheet 121 and the second lower copper sheet 122 to meet the good rectification circuit of the four pins 4 respectively connected to the first upper copper sheet 111, the second upper copper sheet 112, the first lower copper sheet 121 and the second lower copper sheet 122.

[0024] Moreover, the parts of the first upper copper sheet 111 and the second upper copper sheet 112 corresponding to two opposite diode chips 2 are convexly provided with first convex parts 113 downward, and the parts of the first lower copper sheet 121 and the second lower copper sheet 122 corresponding to the other pair of two opposite diode chips 2 are convexly provided with second convex parts 123 upward; The four diode chips 2 include an upper chip 21 and a lower chip 22 arranged in a staggered manner in the vertical direction. The upper chip 21 is located between the second convex part 123 and the first upper copper sheet 111 or the second upper copper sheet 112, and the lower chip 22 is located between the first convex part 113 and the first lower copper sheet 121 or the second lower copper sheet 122.

[0025] Specifically, the flared end of the tapered hole 31 can be located on the upper end face of the epoxy resin encapsulation body 3 or on the lower end face of the epoxy resin encapsulation body 3. When its flared end is located on the upper end face, it is used as an air outlet. The resistance of the hot air rising in the tapered hole 31 is small, which can effectively suppress turbulence and prolong the contact time of hot and cold air; compared with the ordinary straight hole with high air flow resistance, easy to form a "dead zone" and short air flow residence time and other defects, the setting of the tapered hole 31 with the flared end as the air outlet can reduce the hot air flow resistance, reduce turbulence, improve the flow coherence of the air in the tapered hole 31, and also prolong the contact time of hot and cold air to enhance the heat exchange effect between the cold air and the heat dissipation fin group.

[0026] When its flared end is located on the lower end face, it is used as an air inlet. At this time, the air outlet of the tapered hole 31 is the closed end. When the air enters from the air inlet at the bottom end of the tapered hole 31, as the aperture of the tapered hole 31 gradually shrinks, this air is gradually accelerated, so that a low-pressure area is formed at the high-speed air flow at the air outlet at the top end of the tapered hole 31, which can enhance the suction force of the cold air at the bottom, further increase the air inlet speed in the tapered hole 31, and form an efficient cycle; moreover, the hole wall of the tapered hole 31 can also form a streamline guide for the entering air to perform smooth acceleration, avoiding problems such as low flow velocity, turbulence and "dead zone" easily existing in ordinary straight holes.

[0027] Considering that when the flared end of the tapered hole 31 is arranged on the lower end face of the epoxy resin package 3, with the flared end of the tapered hole 31 serving as the air inlet and the narrowed end serving as the air outlet, the flow velocity of the air flow in the tapered hole 31 can be increased, making the active heat dissipation effect formed by means of the internal and external pressure difference more obvious. Therefore, in the embodiment of the present application, it is selected to arrange the flared end of the tapered hole 31 on the lower end face of the epoxy resin package 3. That is, after the rectifier of the present application is installed on the circuit board, the lower end of the tapered hole 31 on the epoxy resin package 3 is a large opening and serves as the air inlet, and the upper end is a small opening and serves as the air outlet. It should be noted that this selection does not limit the setting form of the tapered hole 31 in the embodiment of the present application, but is only a better choice, and another solution can also be selected in other embodiments.

[0028] Thus, through the staggered arrangement of the two upper chips 21 and the two lower chips 22 in the epoxy resin package 3 in the vertical direction, and both the two upper chips 21 and the two lower chips 22 are symmetrically arranged with respect to the central axis of the tapered hole 31, heat dissipation between the two diode chips 2 on the same layer can be non-interfering, and staggered heat dissipation can be carried out between the two diode chips 2 on the same side, so that the interference area between the heat dissipation spaces of each diode chip 2 is extremely small, which helps the diode chips 2 to dissipate heat by means of the upper patch 11, the lower patch 12 and the epoxy resin package 3, and the heat dissipation efficiency of the diode chips 2 can be improved within an effective volume space.

[0029] Moreover, by respectively arranging the first convex portions 113 and the second convex portions 123 on the upper patch 11 and the lower patch 12 in a staggered manner, the soldering of the diode chips 2 between the upper patch 11 and the lower patch 12 can be made more stable, effectively avoiding the occurrence of high-temperature de-soldering. At the same time, the heat generated by each diode chip 2 during operation can be quickly transferred to the heat dissipation fin group at the tapered hole 31 in the middle of the epoxy resin package 3 by means of the heat pipe 5, and these heats can be dissipated by the air flowing in the tapered hole 31, and the improvement of the heat dissipation efficiency is more obvious.

[0030] More importantly, when the air in the conical hole 31 is heated by the heat pipe 5 and the heat dissipation fin group, its density decreases and it naturally rises. The external cold air then enters from the bottom of the conical hole 31 to supplement, forming a natural convection cycle. Moreover, due to the upper-small and lower-large setting of the conical hole 31, the air flow velocity at the upper outlet of the conical hole 31 is relatively large and the air pressure is relatively low, which can enhance the suction force on the cold air at the bottom and promote the rapid outflow of the hot air in the conical hole 31, improving the hot air discharge efficiency and further promoting the heat dissipation effect of the heat dissipation fin group, forming a dual heat dissipation effect composed of active heat dissipation driven by temperature difference + passive heat dissipation of the heat pipe 5 and the heat dissipation fin group. And this way of driving gas flow through the internal and external temperature difference is that the greater the temperature difference between the internal heat source temperature and the external environment temperature, the greater the effect on the air flow promotion. That is, the greater the heat generated when the diode chip 2 works, the greater the air flow velocity in the conical hole 31, and the better the above-mentioned dual heat dissipation effect. The upper limit of the chip junction temperature of the diode chip 2 is generally 150 °C, which provides sufficient conditions for this way of driving gas flow through the internal and external temperature difference, ensuring the stable operation of the active heat dissipation driven by temperature difference in the conical hole 31.

[0031] Compared with ordinary straight holes, there are defects such as high air flow resistance, low flow velocity, easy formation of "dead zones", and short air flow residence time. In essence, it is still passive heat dissipation. However, the setting of the conical hole 31 in the epoxy resin package 3 of the present application can enhance the suction force on the cold air at the bottom, increase the air flow velocity in the conical hole 31 to promote the rapid discharge of hot air, form an efficient cycle, and enhance the heat exchange effect between the cold air and the heat dissipation fin group. The comprehensive heat dissipation efficiency can be increased by at least 35%.

[0032] Further, referring to Figure 4 、 Figure 5 and Figure 6, the heat dissipation fin group includes two annular integral fins 61 axially spaced along the conical hole 31. The evaporation section of the heat pipe 5 corresponding to the lower chip 22 is located in the back groove of the corresponding first convex portion 113, and the condensation section is connected to the upper annular integral fin 61. The evaporation section of the heat pipe 5 corresponding to the upper chip 21 is located in the back groove of the corresponding second convex portion 123, and the condensation section is connected to the lower annular integral fin 61. At the same time, both the first convex portion 113 and the second convex portion 123 have extending convex portions respectively extending to the arc-shaped notches of the upper patch 11 and the lower patch 12, so that the heat pipe 5 is not protruded from the surfaces of the upper patch 11 and the lower patch 12. And an insulating heat-conducting layer is provided between the contact portions of the heat pipe 5 with the upper patch 11 and the lower patch 12 and / or between the contact portions with the heat dissipation fin group. Specifically, an insulating heat-conducting layer is provided between the joint portions of the evaporation section of the heat pipe 5 with the upper patch 11 and the lower patch 12 and between the condensation section of the heat pipe 5 and the annular integral fin 61. The insulating heat-conducting layer can specifically be a boron nitride ceramic coating, a graphene film, an alumina ceramic coating, etc., with a thickness controlled within 10 - 20 μm, which can both conduct heat and insulate. And when welding the heat pipe 5, a low-temperature brazing material is used to avoid damaging the coating.

[0033] And, referring to Figure 3 and Figure 4 , the condensation section of the heat pipe 5 has a semi-circular arc portion 51 adapted to the annular integral fin 61, and the semi-circular arc portion 51 is located on the upper end surface of the annular integral fin 61 to reduce the influence of wind resistance. The annular integral fin 61 is inclined, and its inner edge end is closest to the upper end surface of the epoxy resin encapsulation body 3, specifically inclined upward along the air flow direction in the conical hole 31.

[0034] Thus, by embedding the heat pipe 5 in the back grooves of the first convex portion 113, the second convex portion 123, and the back grooves of the extending convex portions, the heat pipe 5 can be made not to protrude from the surfaces of the upper patch 11 and the lower patch 12, which can greatly reduce the overall thickness of the upper patch 11, the lower patch 12, and the heat pipe 5, and is beneficial to the overall thickness control of the rectifier of the present application. And such a setting is also beneficial to the gap control between the two annular integral fins 61, ensuring that the overall arrangement trend of the heat pipe 5 is horizontal and avoiding breakage after welding at both ends. At the same time, by providing an insulating heat-conducting layer between the heat pipe 5 and the upper patch 11, the lower patch 12, and the annular integral fin 61, it can not only ensure the heat conduction and heat dissipation effects of the heat pipe 5, but also avoid the short-circuit connection of the upper patch 11 and the lower patch 12.

[0035] Moreover, by providing the semi-circular arc portion 51, the contact area between the condensation section of the heat pipe 5 and the annular integral fin 61 can be significantly enhanced, thereby improving the heat dissipation effect of the annular integral fin 61 on the condensation section of the heat pipe 5. Further, by arranging the annular integral fin 61 in an inclined manner, it is beneficial to improve the smoothness of the airflow flowing in the conical hole 31, and it can also increase the effective contact area between the annular integral fin 61 and the flowing airflow, thus improving the heat dissipation effect of the annular integral fin 61.

[0036] However, considering that the annular integral fin 61 near the air inlet of the conical hole 31 contacts the cold air earlier and has a larger outer diameter, it may have a larger heat dissipation area, which makes the temperature reduction effects of the two annular integral fins 61 on the corresponding diode chips 2 different, possibly resulting in unstable operation or shortened lifespan of the four diode chips 2.

[0037] Therefore, in one embodiment, the inclination angle of the annular integral fin 61 near the air inlet can be set to be greater than that of the annular integral fin 61 near the air outlet, so as to reduce the intercepting effect of the annular integral fin 61 near the air inlet on the cold air introduced from the air inlet of the conical hole 31, and minimize the heat dissipation and temperature reduction differences of the two annular integral fins 61 on the corresponding two groups of heat pipes 5 as much as possible.

[0038] In another embodiment, the materials of the two annular integral fins 61 can also be set to be different. For example, the material of the annular integral fin 61 near the air outlet is selected as a high thermal conductivity composite material, such as aluminum-based graphene, while the material of the annular integral fin 61 near the air inlet is selected as a conventional aluminum material, and the heat dissipation and temperature reduction differences are balanced through the difference in the thermal conductivity coefficients of the two materials.

[0039] In another embodiment, the annular integral fin 61 can also be arranged to be integrated by a plurality of ultra-thin fins. The gap between two adjacent ultra-thin fins in the annular integral fin 61 near the air outlet is smaller and the number of ultra-thin fins is larger, while the gap between two adjacent ultra-thin fins in the annular integral fin 61 near the air inlet is larger and the number of ultra-thin fins is smaller. In this way, the heat dissipation and temperature reduction differences between the two can also be balanced.

[0040] Further, to improve the heat dissipation effect of the heat dissipation fin group of the present application, refer to Figure 4 and Figure 6, the heat dissipation fin group further includes a plurality of split fins 62 that are circumferentially and equally spaced along the axial direction of the conical hole 31. The plurality of split fins 62 are combined into an annular heat dissipation structure. The split fins 62 are arranged on one side of the annular integral fin 61 located below, close to the closing end of the conical hole 31. A bimetallic strip 63 is fixedly connected between the split fin 62 and the wall of the conical hole 31. The bimetallic strip 63 is configured to drive the split fin 62 to flip towards the annular integral fin 61 when its body temperature is greater than a set value, such as 100°C. A honeycomb copper mesh ring 64 is provided on the wall of the conical hole 31 between the bimetallic strip 63 and the adjacent annular integral fin 61.

[0041] Thus, the annular heat dissipation structure formed by combining the plurality of split fins 62 can form a linear flow guiding structure on the wall of the conical hole 31 with the two annular integral fins 61, which can ensure the smooth flow of the air flow in the conical hole 31 as much as possible. The setting of the honeycomb copper mesh ring 64 can conduct heat connection between the plurality of bimetallic strips 63 and the roots of the adjacent annular integral fins 61. Thus, the bimetallic strip 63 can monitor the temperature of the root of the annular integral fin 61 in real time. Once the temperature of the root of the annular integral fin 61 exceeds the preset value, the bimetallic strip 63 undergoes an upward bending deformation, causing the split fin 62 thereon to flip towards the annular integral fin 61, thereby increasing the inclination angle of the annular heat dissipation structure, reducing the air flow concentration at the air inlet of the conical hole 31, reducing the influence on the air flow entering the conical hole 31 at the air inlet, and at the same time increasing the windward surface area of the annular integral fin 61 located below in actual contact with the air flow, which can improve the overall heat dissipation effect of the two annular integral fins 61.

[0042] In order to ensure the air intake volume at the air inlet of the conical hole 31, referring to Figure 4 and Figure 7 , a plurality of spiral flow guiding fins 7 are fixedly connected to the lower end surface of the epoxy resin encapsulation body 3, which are circumferentially and equally spaced along the axial direction of the conical hole 31. The spiral flow guiding fins 7 are arranged radially along the conical hole 31. The side of the spiral flow guiding fin 7 facing away from the epoxy resin encapsulation body 3 is flush with the free end of the pin 4; specifically, the spiral angle of the spiral flow guiding fin 7 is 30° - 45°, and four are provided to minimize the influence on the air flow pressure drop and flow rate at the air inlet.

[0043] Thus, when the external air flows along the gap between the rectifier of the present application and the circuit board towards the air inlet of the conical hole 31 under the suction effect of the air inlet of the conical hole 31, under the guidance of the multiple spiral guide vanes 7, the air flow entering the air inlet of the conical hole 31 can be made to be in a swirling state and the air flow speed can be accelerated. On the one hand, after the air flow enters the conical hole 31, a spiral movement is formed, which can not only enhance the contact area between the air flow and the heat dissipation fin group and increase the contact duration between the air flow and the heat dissipation fin group, improve the heat dissipation efficiency, but also guide the air flow to flow concentratedly along the axis direction of the conical hole 31, reduce the lateral diffusion, and utilize the pressure difference between the upper and lower ends of the conical hole 31 to accelerate the natural convection; on the other hand, the generation of the spiral air flow can also eliminate the air flow separation at the air inlet, avoid the direct impact of hot and cold air, reduce the formation of local eddies, and can improve the uniformity of the air flow speed distribution at the air inlet compared with the conventional straight hole setting. Therefore, the setting of the spiral guide vanes 7 can form forced swirling and turbulence strengthening, can significantly improve the heat dissipation uniformity and heat dissipation efficiency in the conical hole 31, and is particularly suitable for the heat dissipation scenario of high-power density electronic devices with limited space.

[0044] In addition, considering that the typical thickness of the patch-type rectifier of the present application is only 1.4 - 1.6 mm, it should be particularly noted that when assembling the present application, first weld and fix the upper patch 11, the lower patch 12 and the four diode chips 2 therein, and then weld the heat pipe 5 on the upper patch 11 and the lower patch 12. After the heat pipe 5 is welded, position the two annular integral fins 61, the multiple split fins 62 and the multiple bimetallic sheets 63 with a mold. The outer wall of the mold fits the hole wall of the conical hole 31 opening, and then gradually form an epoxy resin package 3 by means of hierarchical encapsulation; the outer edges of the annular integral fins 61 and the bimetallic sheets 63 need to be embedded into the epoxy resin package 3 to a certain depth to meet the structural strength requirements. After removing the mold, finally weld or bond the honeycomb copper mesh ring 64 with heat-conducting glue; if necessary, the hole wall of the conical hole 31 can also be trimmed for burrs.

[0045] Unless otherwise defined, the technical terms or scientific terms used in the present application shall have the ordinary meanings understood by those of ordinary skill in the field to which the present application belongs. The "first", "second", "third" and similar words used in the specification and claims of the present application do not indicate any order, quantity or importance, but are only used to distinguish different components. Words such as "a" or "one" do not indicate a quantity limitation either, but indicate that there is at least one. Words such as "comprising" or "including" mean that the elements or objects appearing before "comprising" or "including" cover the elements or objects listed after "comprising" or "including" and their equivalents, and do not exclude other elements or objects. "Upper", "lower", "left", "right", etc. are only used to indicate the relative position relationship. When the absolute position of the object to be described changes, the relative position relationship may also change accordingly.

[0046] The above are all preferred embodiments of the present application, and do not limit the protection scope of the present application. Therefore, all equivalent changes made according to the structure, shape, and principle of the present application shall be covered within the protection scope of the present application.

Claims

1. A high-power thin-type SMD bridge rectifier, comprising an upper SMD (11), a lower SMD (12), four diode chips (2), an epoxy resin package (3), and four pins (4) extending out of the epoxy resin package (3), characterized in that: A tapered hole (31) is formed through the middle of the epoxy resin encapsulation body (3) along its thickness direction, and the four diode chips (2) are arranged in a rhombus shape around the tapered hole (31); A heat dissipation fin group arranged in an annular manner is installed on the wall of the conical hole (31), and four heat pipes (5) are arranged in the epoxy resin package (3). The evaporation section of the heat pipe (5) is thermally connected to one of the diode chips (2), and the condensation section extends to be welded and fixed to the heat dissipation fin group.

2. A high-power thin-type SMD bridge rectifier according to claim 1, characterized in that: The upper patch (11) comprises a first upper copper sheet (111) and a second upper copper sheet (112) which are insulated and respectively correspond to the two diode chips (2); the lower patch (12) comprises a first lower copper sheet (121) and a second lower copper sheet (122) which are insulated and respectively correspond to the two diode chips (2); The two diode chips (2) on the first lower copper sheet (121) and the second lower copper sheet (122) adjacent to the insulating portion of the two sheets correspond to the first upper copper sheet (111), and the two diode chips (2) on the first lower copper sheet (121) and the second lower copper sheet (122) adjacent to the other insulating portion of the two sheets correspond to the second upper copper sheet (112).

3. A high-power thin-type SMD bridge rectifier according to claim 2, characterized in that: The first upper copper sheet (111) and the second upper copper sheet (112) are provided with a first convex portion (113) protruding downwards at positions corresponding to the two opposite diode chips (2), and the first lower copper sheet (121) and the second lower copper sheet (122) are provided with a second convex portion (123) protruding upwards at positions corresponding to another pair of opposite diode chips (2); The four diode chips (2) comprise an upper chip (21) and a lower chip (22) which are staggered in a vertical direction, wherein the upper chip (21) is located between the second convex portion (123) and the first upper copper sheet (111) or the second upper copper sheet (112), and the lower chip (22) is located between the first convex portion (113) and the first lower copper sheet (121) or the second lower copper sheet (122).

4. A high-power thin-type SMD bridge rectifier according to claim 3, characterized in that: The heat dissipation fin group comprises two annular integral fins (61) axially spaced apart from each other along the conical hole (31); the evaporation section of the heat pipe (5) corresponding to the lower chip (22) is located in a groove on the back side of the corresponding first protrusion (113), and the condensation section is connected to the annular integral fin (61) located above; the evaporation section of the heat pipe (5) corresponding to the upper chip (21) is located in a groove on the back side of the corresponding second protrusion (123), and the condensation section is connected to the annular integral fin (61) located below.

5. A high-power thin-type SMD bridge rectifier according to claim 4, characterized in that: The condensing section of the heat pipe (5) has a semi-circular arc portion (51) adapted to the annular integrated fin (61), and the semi-circular arc portion (51) is located on the upper end surface of the annular integrated fin (61).

6. A high-power thin-type SMD bridge rectifier according to claim 3, characterized in that: The annular integrated fin (61) is arranged at an angle, and its inner edge end is closest to the upper end surface of the epoxy resin packaging body (3).

7. A high-power thin-type SMD bridge rectifier according to claim 3, characterized in that: The heat dissipation fin group further comprises a plurality of split fins (62) distributed in an equidistant circular array along the axial direction of the tapered hole (31); the split fins (62) are arranged on a side of the annular integral fin (61) located below and close to the lower end surface of the epoxy resin package (3); a bimetallic strip (63) is fixedly connected between the split fin (62) and the hole wall of the tapered hole (31); the bimetallic strip (63) is configured to drive the split fin (62) to flip in a direction close to the annular integral fin (61) when its body-sensing temperature is greater than a set value.

8. A high-power thin-type SMD bridge rectifier according to claim 7, characterized in that: A honeycomb copper mesh ring (64) is provided on the wall of the conical hole (31) and is located between the bimetallic strip (63) and the adjacent annular integral fin (61).

9. A high-power thin-type SMD bridge rectifier according to claim 1, characterized in that: A plurality of spiral guide plates (7) are fixedly connected to the lower end surface of the epoxy resin encapsulation body (3) and are distributed in a circular array with equal spacing in the axial direction of the tapered hole (31). The spiral guide plates (7) are arranged radially along the tapered hole (31), and the side of the spiral guide plates (7) facing away from the epoxy resin encapsulation body (3) is flush with the free end of the pin (4).

10. A high-power thin-type SMD bridge rectifier according to claim 2, characterized in that: An insulating heat-conducting layer is provided between the contact portions of the heat pipe (5) with the upper patch (11) and the lower patch (12) and / or between the contact portions of the heat pipe (5) and the heat dissipation fin group.

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