Double-sided heat dissipation type MOS (Metal Oxide Semiconductor) chip stacking and packaging structure

Abstract

The invention relates to the technical field of semiconductor devices, in particular to a double-sided heat dissipation type MOS (Metal Oxide Semiconductor) chip stacking and packaging structure. The package structure includes a package and a stack. According to the plastic packaging box, when the upper plastic packaging body and the lower plastic packaging body are matched through the buckles to form the complete box body, the inner side shafts synchronously extrude the arc-shaped edges, the outer sleeve is driven to rotate, and the second through opening is aligned to the first through opening. The heat transfer rod is promoted to press and fill preset heat-conducting silicone grease into interface gaps among the metal heat-conducting structure, the silicone grease heat-conducting structure and the pressing and covering structure through the through hole, in the packaging system, heat can be efficiently conducted through the heat transfer shaft and the heat transfer rod, and the overall heat dissipation efficiency is improved; polyvinylidene fluoride is adopted as a matrix, hexagonal boron nitride and spherical aluminum nitride are compounded to construct a multi-dimensional synergistic heat conduction network, and a complete efficient heat dissipation scheme from a chip to a heat dissipation terminal is jointly formed by combining the active grease injection heat dissipation mechanism.

Description

Technical Field

[0001] This invention relates to the field of semiconductor device technology, and more specifically, to a double-sided heat dissipation type MOS chip stacked packaging structure. Background Technology

[0002] MOS chips are a core component of semiconductor devices, and their technology directly determines the chip's performance and functionality. MOS chips are integrated circuits composed of metal-oxide-semiconductor field-effect transistors (MOSFETs) as their core components. MOS chips utilize the voltage control characteristics of MOSFETs to achieve functions such as signal amplification and switching control, and are widely used in analog circuits, digital circuits, and mixed-signal systems.

[0003] For example, CN112331610A discloses a power MOS chip with a multilayer composite substrate, including a silicon substrate, an epitaxial layer formed on the substrate, and gate and source metallization structures disposed on the surface of the epitaxial layer. The chip adopts a vertical conductivity topology and is electrically connected to the packaging substrate through a drain metal on the back side. Although the above-mentioned MOS chip structure has a low on-resistance, its heat dissipation path is singular. Heat can only be transferred downwards through the drain metal layer on the back side to the packaging substrate, and then diffused to the external heat sink through the substrate. Because the front side of the chip is covered with multiple layers of dielectric and metal, its thermal conductivity is poor, which makes the device prone to forming local hot spots under high temperature and high current conditions, reducing the reliability and long-term service life of the chip.

[0004] As chip size shrinks and power levels increase, traditional single-sided heat dissipation structures and low thermal conductivity materials are no longer sufficient to meet heat dissipation requirements. The thermal resistance between the chip junction and the environment increases significantly, causing the device to degrade in performance due to excessively high temperatures during continuous operation, and even leading to thermal failure.

[0005] Therefore, there is an urgent need for a new packaging structure that can enhance the overall heat dissipation capacity of the chip and optimize the thermal path distribution. Summary of the Invention

[0006] The purpose of this invention is to solve the problem in the prior art where the performance of MOS chips degrades or even fails due to excessive temperature during continuous operation because of the limited heat dissipation capacity of stacked packaging structures and materials.

[0007] To achieve the above objectives, the present invention aims to provide a double-sided heat dissipation type MOS chip stacked package structure, including a package and stacked components mounted within the package;

[0008] The package includes a lower molding body and an upper molding body. The lower molding body and the upper molding body are snapped together to form a hollow box structure. A first heat sink is provided in the lower molding body. A thermal grease structure is symmetrically fixed to the top of the first heat sink. A second heat sink is provided in the upper molding body. A metal thermal structure is symmetrically fixed to the bottom of the second heat sink.

[0009] The stacked component includes multiple stacked pressing structures and multiple pins snapped onto both sides of the pressing structures. The pressing structures are located inside the housing structure, and one end of the pins penetrates through the side wall of the housing structure.

[0010] The top of the silicone grease thermal conductive structure passes through the overlay structure, and the bottom of the metal thermal conductive structure is inserted into the silicone grease thermal conductive structure.

[0011] When the upper molded enclosure is installed and pushed downwards, the metal thermal conductive structure inserts into the thermal grease structure and comes into contact with the thermal grease. When the bottom of the upper molded enclosure and the outer wall of the lower molded enclosure snap together to form a complete box structure, the thermal grease structure rotates under the pressure of the metal thermal conductive structure to expose a gap for the thermal grease to flow. At the same time, the thermal grease flows under the pressure of the metal thermal conductive structure to fill the gaps between the metal thermal conductive structure and the thermal grease structure, and between the thermal grease structure and the pressing structure, thereby ensuring the heat conduction efficiency within the MOS chip stacked package structure and improving the heat dissipation effect of the package structure.

[0012] As a further improvement to this technical solution, the pressing structure includes an upper pressing plate, a lower pressing plate, and a chip. Both the upper pressing plate and the lower pressing plate are insulating heat dissipation plates, and the contact surfaces of the upper pressing plate and the lower pressing plate are provided with grooves whose shapes match the chip, and the chip is located in the grooves.

[0013] Both ends of the upper and lower pressure plates have through-holes for the thermal grease structure to pass through. Both ends of the upper and lower pressure plates have plate grooves that are connected to the grooves. The connection ends of the pins are engaged with the plate grooves.

[0014] As a further improvement to this technical solution, the lower molding body includes a lower molding shell, the lower molding shell being a box structure with the top surface exposed, and the first heat sink including a lower heat dissipation plate embedded in the bottom of the lower molding shell, the lower heat dissipation plate having inclined surfaces at both ends, and the inclined surfaces of the lower heat dissipation plate penetrating the side of the lower molding shell.

[0015] The upper plastic encapsulation body includes an upper plastic encapsulation shell, which is a box structure with an exposed bottom surface. The second heat sink includes an upper heat dissipation plate embedded in the top of the upper plastic encapsulation shell, and the surface of the upper heat dissipation plate is provided with heat dissipation fins. Hook edges are fixedly connected to the bottom of the left and right ends of the upper plastic encapsulation shell, and the hook edges are engaged with the inclined end of the lower heat dissipation plate.

[0016] Both the lower and upper plastic shells have notches on their side walls for the pins to pass through.

[0017] As a further improvement to this technical solution, the thermal grease conductive structure includes a heat transfer shaft and an outer sleeve sleeved around the heat transfer shaft. The bottom of the heat transfer shaft has a first opening for the thermally conductive thermal grease to pass through, and the bottom of the outer sleeve has a second opening. The top of the inner wall of the outer sleeve is provided with an arc-shaped edge. The metal thermal conductive structure includes a pair of heat transfer rods. The top of the heat transfer rods is fixedly connected to the upper heat spreader plate, and a side shaft is fixedly connected to the side wall of the heat transfer rods near the upper heat spreader plate.

[0018] As a further improvement to this technical solution, the method for preparing the insulating heat sink includes the following steps:

[0019] Step S1: Weigh out 10-15% polyvinylidene fluoride, 15-20% hexagonal boron nitride, 1-2% SiO2-coated multi-walled carbon nanotubes, 1-2% silane coupling agent, 15-25% spherical aluminum nitride, and the balance is N-methylpyrrolidone according to the mass ratio.

[0020] Hexagonal boron nitride, spherical aluminum nitride and SiO2 were coated with multi-walled carbon nanotubes, placed in a flask, anhydrous ethanol was added and ultrasonically dispersed.

[0021] Step S2: Dilute the weighed silane coupling agent with ethanol and add it dropwise to the packing suspension under stirring. Stir and reflux the system at 70-80℃ for 2 hours. After completion, filter and wash with ethanol to obtain filter cake. Then grind the filter cake to obtain modified composite thermally conductive packing.

[0022] In a container equipped with a stirrer, add N-methylpyrrolidone. Start stirring, add polyvinylidene fluoride powder, and continue stirring in a 60°C water bath to form a transparent liquid. Then, add the modified composite thermally conductive filler to the transparent liquid and stir to obtain a slurry.

[0023] Step S3: Apply the slurry to the substrate using a doctor blade coater, and then transfer the coated wet film along with the substrate to a ventilated drying oven for drying to form a preform.

[0024] Step S4: Carefully peel the dried preform from the substrate and cut it to the target size. Place the cut preform into the mold of the flatbed hot press;

[0025] After the pressure holding period, the temperature is cooled to below 60°C while maintaining the pressure. Then, the pressure is released and the mold is removed to obtain the final insulating heat sink.

[0026] As a further improvement to this technical solution, in step S2, the filter cake is dried in a vacuum drying oven at 80℃ for 6 hours. The modified composite packing is then ground and sieved to obtain the modified composite thermally conductive packing.

[0027] As a further improvement to this technical solution, in step S2, the transparent adhesive liquid is stirred for 10-15 minutes in a planetary centrifugal mixer under vacuum conditions in revolution / rotation mode to obtain a slurry.

[0028] As a further improvement to this technical solution, in step S3, the scraper gap is 1.5-2 times the thickness of the target insulating heat sink.

[0029] As a further improvement to this technical solution, in step S3, the embryo is horizontally placed at 60-80℃ for 2-4 hours to obtain the embryo.

[0030] As a further improvement to this technical solution, in step S4, the temperature of the flatbed hot press is 180-190℃, the pressure is 15-20MPa, and the hot pressing time is 15-20min.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0032] 1. In this double-sided heat dissipation type MOS chip stacked package structure, when the bottom end of the upper molded body and the outer wall of the lower molded body are snapped together to form a complete box structure, the side shaft contacts the arc edge and squeezes the arc edge, causing the outer sleeve to rotate. The second port connects with the first port, and the thermal grease flows under the pressure of the heat transfer rod. It flows out of the heat transfer shaft and enters and fills the gap between the thermal grease thermal structure and the through port. This fills the gap between the metal thermal structure and the thermal grease thermal structure, and between the thermal grease thermal structure and the pressing structure. The heat generated in the middle layer can be conducted to the lower heat spreader and the upper heat spreader through the heat transfer shaft, the first port, and the heat transfer rod, improving the heat dissipation efficiency. This ensures the heat conduction efficiency within the MOS chip stacked package structure and improves the heat dissipation effect of the package structure.

[0033] 2. In this double-sided heat dissipation MOS chip stacked packaging structure, a flexible substrate framework is first constructed using polyvinylidene fluoride (PVDF). A synergistic thermal conductivity network is formed by the two-dimensional sheet structure of hexagonal boron nitride and the three-dimensional filling characteristics of spherical aluminum nitride. SiO2-coated multi-walled carbon nanotubes are introduced as nano-bridging units. Their unique one-dimensional tubular structure effectively connects the micron-level filler gaps, significantly improving the thermal conductivity in the vertical direction. At the same time, the surface modification effect of silane coupling agent greatly reduces the interfacial thermal resistance between the filler and the substrate, while the precise control of N-methylpyrrolidone solvent ensures the uniform distribution of each component and ideal rheological properties.

[0034] Furthermore, by optimizing material pretreatment and molding processes, precise control of component structure and performance is achieved, effectively eliminating internal porosity, interface defects and stress concentration in the material, and preparing an advanced insulating heat sink, providing an ideal packaging solution for double-sided heat dissipation of high power density MOS chips. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0036] Figure 2 This is a schematic cross-sectional view of the overall structure of the present invention;

[0037] Figure 3 This is a schematic diagram showing the overall structure of the present invention broken down;

[0038] Figure 4 This is a schematic diagram of the stacked component structure of the present invention;

[0039] Figure 5 This is a cross-sectional view of the overlay structure of the present invention.

[0040] Figure 6 This is a schematic cross-sectional view of the lower sealing body of the present invention;

[0041] Figure 7 This is a schematic diagram showing the disassembled structure of the lower heat spreader of the present invention;

[0042] Figure 8 This is a schematic cross-sectional view of the upper sealing body of the present invention;

[0043] Figure 9 This is a schematic cross-sectional view of the lower and upper molding bodies of the present invention.

[0044] Figure 10 This is a flowchart illustrating the preparation process of the insulating heat sink of the present invention.

[0045] The meanings of the labels in the diagram are as follows:

[0046] 1. Encapsulation component; 11. Lower molding body; 111. Lower molding shell; 112. Lower heat spreader; 1121. Heat transfer shaft; 1122. Outer sleeve; 1123. First port; 1124. Second port; 1125. Arc edge; 12. Upper molding body; 121. Upper molding shell; 1211. Hook edge; 122. Upper heat spreader; 1221. Heat transfer rod; 1222. Side shaft;

[0047] 2. Stacked components; 21. Overlay structure; 211. Upper overlay plate; 212. Lower overlay plate; 213. Chip; 214. Through-hole; 215. Board groove; 22. Pin. Detailed Implementation

[0048] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0049] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0050] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0051] Example 1

[0052] Please see Figure 1 , Figure 2 , Figure 3 , Figure 4 As shown, the purpose of this embodiment of the invention is to provide a double-sided heat dissipation type MOS chip stacked package structure, including a package 1 and a stack 2 installed in the package 1;

[0053] The package 1 includes a lower molding body 11 and an upper molding body 12. The lower molding body 11 and the upper molding body 12 are snapped together to form a hollow box structure. A first heat sink is provided inside the lower molding body 11. A thermal grease structure is symmetrically fixedly connected to the top of the first heat sink. A second heat sink is provided inside the upper molding body 12. A metal thermal structure is symmetrically fixedly connected to the bottom of the second heat sink.

[0054] The stacked component 2 includes multiple stacked pressing structures 21 and multiple pins 22 snapped onto both sides of the pressing structures 21. The pressing structures 21 are located inside the housing structure, and one end of the pins 22 penetrates through the side wall of the housing structure.

[0055] The top of the silicone grease thermal conductive structure passes through the pressure covering structure 21, and the bottom of the metal thermal conductive structure is inserted into the silicone grease thermal conductive structure.

[0056] After stacking multiple pressing structures 21 and snapping them with pins 22, the pressing structure 21 is placed on top of the lower molding body 11, so that the thermal grease structure passes upward through the pressing structure 21 and the pins 22 are aligned with the notches on the lower molding body 11 and the upper molding body 12. Then, an appropriate amount of thermal grease is filled into the thermal grease structure. Finally, the upper molding body 12 is pushed downward from the top of the pressing structure 21, so that the inner wall of the upper molding body 12 moves down along the outer wall of the lower molding body 11 until the bottom of the upper molding body 12 snaps into the outer wall of the lower molding body 11 to form a complete box structure.

[0057] When the upper molding package 12 is installed and pushed downwards, the metal thermal conductive structure is inserted into the silicone grease thermal conductive structure and comes into contact with the silicone grease. When the bottom end of the upper molding package 12 is engaged with the outer wall of the lower molding package 11 to form a complete box structure, the silicone grease thermal conductive structure rotates under the pressure of the metal thermal conductive structure to expose a gap for the flow of thermal conductive silicone grease. At the same time, the thermal conductive silicone grease flows under the pressure of the metal thermal conductive structure to fill the gaps between the metal thermal conductive structure and the silicone grease thermal conductive structure, and between the silicone grease thermal conductive structure and the pressure-covering structure 21, thereby ensuring the heat conduction efficiency within the MOS chip stacked package structure and improving the heat dissipation effect of the package structure.

[0058] The above structure is disclosed below:

[0059] like Figure 4 , Figure 5 As shown, the pressing structure 21 includes an upper pressing plate 211, a lower pressing plate 212 and a chip 213. The upper pressing plate 211 and the lower pressing plate 212 are both insulating heat dissipation plates, and the contact surfaces of the upper pressing plate 211 and the lower pressing plate 212 are provided with grooves whose shape matches the chip 213, and the chip 213 is located in the grooves.

[0060] Both ends of the upper pressure plate 211 and the lower pressure plate 212 are provided with through holes 214 for the thermal conductive structure of the silicone grease to pass through. Both ends of the upper pressure plate 211 and the lower pressure plate 212 are provided with plate grooves 215 that are connected to the groove. The shape of the connecting end of the pin 22 matches the shape of the plate groove 215, and the connecting end of the pin 22 is engaged with the plate groove 215.

[0061] Chip 213 is placed in the groove of upper pressure plate 211, and then lower pressure plate 212 is aligned and attached to upper pressure plate 211 to form a complete pressure structure 21. This allows chip 213 to achieve double-sided heat dissipation through upper pressure plate 211 and lower pressure plate 212 when it is working. Furthermore, by setting the plate groove 215, the pin 22 can be locked in place, while also providing space to achieve electrical connections between multiple chips 213 and between chips 213 and pins 22.

[0062] After stacking multiple pressing structures 21 and inserting multiple pins 22 into the board slot 215 to form a stacked component 2, the stacked component 2 needs to be sealed and installed, such as... Figure 3 , Figure 6 , Figure 8 As shown, the lower plastic seal 11 includes a lower plastic seal shell 111. The lower plastic seal shell 111 is a box structure with the top surface exposed. The first heat sink includes a lower heat dissipation plate 112 embedded in the bottom of the lower plastic seal shell 111. The two ends of the lower heat dissipation plate 112 are inclined surfaces, and the inclined ends of the lower heat dissipation plate 112 penetrate through the side of the lower plastic seal shell 111.

[0063] The upper plastic seal 12 includes an upper plastic seal shell 121, which is a box structure with an exposed bottom surface. The second heat sink includes an upper heat dissipation plate 122 embedded in the top of the upper plastic seal shell 121, and the surface of the upper heat dissipation plate 122 is provided with heat dissipation fins. Hook edges 1211 are fixedly connected to the bottom of the left and right ends of the upper plastic seal shell 121, and the hook edges 1211 are engaged with the inclined end of the lower heat dissipation plate 112.

[0064] Both the lower plastic casing 111 and the upper plastic casing 121 have openings on their side walls for the pins 22 to pass through.

[0065] The stacked component 2 is inserted into the lower plastic shell 111 from the top of the lower plastic shell 111. When inserting, the pin 22 is inserted into the notch. Then, the upper plastic shell 121 is pressed down from the top of the stacked component 2, so that the hook edges 1211 at both ends of the upper plastic shell 121 move along the outer surface of the side wall of the lower plastic shell 111 until the hook edges 1211 pass through the inclined end of the lower heat spreader 112 and are locked in place. This closes the lower plastic shell 111 and the upper plastic shell 121 to form a complete box structure. Moreover, the lower heat spreader 112 and the upper heat spreader 122 are used to dissipate heat from the top and bottom surfaces of the box structure.

[0066] Considering that the heat generated by the chip 213 located at or near the top and bottom of the pressure-coated structure 21 during operation can be conducted to the lower heat dissipation plate 112 or the upper heat dissipation plate 122 through the upper pressure-coated plate 211 and the lower pressure-coated plate 212, thereby achieving rapid heat dissipation, the working heat of the chip 213 located in the middle layer of the pressure-coated structure 21 can only be indirectly conducted to the lower heat dissipation plate 112 or the upper heat dissipation plate 122 through the multiple layers of upper pressure-coated plate 211 and lower pressure-coated plate 212, resulting in poor heat dissipation efficiency and thus causing heat accumulation in the middle layer of the pressure-coated structure 21.

[0067] Therefore, please refer to Figure 7 , Figure 8 , Figure 9As shown, the thermal grease conductive structure includes a heat transfer shaft 1121 and an outer sleeve 1122 surrounding the heat transfer shaft 1121. The bottom of the heat transfer shaft 1121 has a first opening 1123 for the thermally conductive silicone grease to pass through, and the bottom of the outer sleeve 1122 has a second opening 1124. The top of the inner wall of the outer sleeve 1122 is provided with an arc-shaped edge 1125. The metal thermal conductive structure includes a pair of heat transfer rods 1221. The top of the heat transfer rods 1221 is fixedly connected to the upper heat spreader 122, and a [missing information - likely a component or material] is fixedly connected to the side wall of the heat transfer rods 1221 near the upper heat spreader 122. In the initial state, the second port 1124 of the side shaft 1222 is not connected to the first port 1123. When the pressing structure 21 is placed into the lower plastic shell 111, the heat transfer shaft 1121 and the outer sleeve 1122 pass upward through the through port 214. At this time, thermally conductive silicone grease is injected into the heat transfer shaft 1121. Then, the upper plastic shell 121 is pressed downward from the top of the stack 2, so that the hooks 1211 at both ends of the upper plastic shell 121 move along the outer surface of the side wall of the lower plastic shell 111 until the hooks 1211 pass through the inclined end of the lower heat spreader 112 and are locked. The heat transfer rod 1221 passes through the outer sleeve 1122 and is inserted into the heat transfer shaft 1121 when the upper plastic seal 121 is pressed down from the top of the stacked parts 2. When the bottom of the upper plastic seal 12 is engaged with the outer wall of the lower plastic seal 11 to form a complete box structure, the side shaft 1222 contacts the arc-shaped edge 1125 and squeezes the arc-shaped edge 1125, causing the outer sleeve 1122 to rotate. The second port 1124 communicates with the first port 1123, and the thermal grease is squeezed into the heat transfer rod 1221. The heat is pressed down and flows out of the heat transfer shaft 1121 into and fills the gap between the thermal grease structure and the through-hole 214. This fills the gap between the metal thermal structure and the thermal grease structure, and between the thermal grease structure and the pressing structure 21. The heat generated in the intermediate layer can be conducted to the lower heat spreader 112 and the upper heat spreader 122 through the heat transfer shaft 1121, the first through-hole 1123, and the heat transfer rod 1221, thereby improving the heat dissipation efficiency and ensuring the heat conduction efficiency within the MOS chip stacked package structure, thus improving the heat dissipation effect of the package structure.

[0068] Example 2

[0069] This embodiment provides a method for preparing the insulating heat dissipation plate for the upper pressure plate 211 and the lower pressure plate 212 in Embodiment 1 above, including the following steps:

[0070] Step S1: Weigh out 10% polyvinylidene fluoride, 20% hexagonal boron nitride, 1% SiO2-coated multi-walled carbon nanotubes, 2% silane coupling agent, 15% spherical aluminum nitride, and the balance is N-methylpyrrolidone according to the mass ratio.

[0071] Hexagonal boron nitride, spherical aluminum nitride, and SiO2 were coated onto multi-walled carbon nanotubes, placed in a flask, and an appropriate amount of anhydrous ethanol was added and ultrasonically dispersed.

[0072] Step S2: Dilute the weighed silane coupling agent with ethanol, and add it dropwise to the packing suspension while stirring. Reflux the system at 80°C for 2 hours to complete the chemical modification of the packing surface. After the reaction is complete, filter and wash with ethanol to obtain a filter cake. Grind the filter cake to obtain the modified composite thermally conductive packing. Specifically, dry the filter cake in a vacuum drying oven at 80°C for 6 hours. Grind and sieve the modified composite packing (200 mesh) to obtain the modified composite thermally conductive packing.

[0073] Add N-methylpyrrolidone to a container equipped with a stirrer. Start stirring and slowly add polyvinylidene fluoride powder. Continue stirring in a 60°C water bath until the polyvinylidene fluoride powder is completely dissolved to form a transparent liquid. Then, gradually and slowly add all the modified composite thermally conductive filler obtained in the first step to the transparent liquid. Use a planetary centrifuge to stir the transparent liquid under vacuum in revolution / rotation mode for 10 minutes to completely break up agglomerates and obtain an extremely uniform slurry.

[0074] Step S3: Apply the homogenized slurry to a smooth substrate (such as glass or release film) using a doctor blade coater. The doctor blade gap should be twice the thickness of the target insulating heat sink. Then, transfer the coated wet film along with the substrate to a ventilated drying oven and let it stand horizontally at 60°C for 4 hours to allow most of the N-methylpyrrolidone to evaporate gently, resulting in a preform with a certain strength.

[0075] Step S4: Carefully peel the dried preform from the substrate and cut it to the target size. Place the cut preform into the mold of a preheated flatbed hot press. The temperature of the flatbed hot press is 180℃, the pressure is 20MPa, and the hot pressing time is 15min.

[0076] After the pressure holding period, the temperature is cooled to below 60°C while maintaining the pressure. Then, the pressure is released and the mold is removed to obtain the final insulating heat sink.

[0077] Example 3

[0078] This embodiment provides a method for preparing the insulating heat dissipation plate for the upper pressure plate 211 and the lower pressure plate 212 in Embodiment 1 above, including the following steps:

[0079] Step S1: Weigh out 12% polyvinylidene fluoride, 18% hexagonal boron nitride, 1% SiO2-coated multi-walled carbon nanotubes, 1% silane coupling agent, 20% spherical aluminum nitride, and the balance is N-methylpyrrolidone according to the mass ratio.

[0080] Hexagonal boron nitride, spherical aluminum nitride, and SiO2 were coated onto multi-walled carbon nanotubes, placed in a flask, and an appropriate amount of anhydrous ethanol was added and ultrasonically dispersed.

[0081] Step S2: Dilute the weighed silane coupling agent with ethanol, and add it dropwise to the packing suspension while stirring. Reflux the system at 75°C for 2 hours to complete the chemical modification of the packing surface. After the reaction is complete, filter and wash with ethanol to obtain a filter cake. Grind the filter cake to obtain the modified composite thermally conductive packing. Specifically, dry the filter cake in a vacuum drying oven at 80°C for 6 hours. Grind the modified composite packing and sieve it (200 mesh) to obtain the modified composite thermally conductive packing.

[0082] Add N-methylpyrrolidone to a container equipped with a stirrer. Start stirring and slowly add polyvinylidene fluoride powder. Continue stirring in a 60°C water bath until the polyvinylidene fluoride powder is completely dissolved to form a transparent liquid. Then, gradually and slowly add all the modified composite thermally conductive filler obtained in the first step to the transparent liquid. Use a planetary centrifuge to stir the transparent liquid under vacuum in revolution / rotation mode for 12 minutes to completely break up agglomerates and obtain an extremely uniform slurry.

[0083] Step S3: Apply the homogenized slurry to a smooth substrate (such as glass or release film) using a doctor blade coater. The doctor blade gap should be twice the thickness of the target insulating heat sink. Then, transfer the coated wet film along with the substrate to a ventilated drying oven and let it stand horizontally at 70°C for 3 hours to allow most of the N-methylpyrrolidone to evaporate gently, resulting in a preform with a certain strength.

[0084] Step S4: Carefully peel the dried preform from the substrate and cut it to the target size. Place the cut preform into the mold of a preheated flatbed hot press. The temperature of the flatbed hot press is 180℃, the pressure is 20MPa, and the hot pressing time is 15min.

[0085] After the pressure holding period, the temperature is cooled to below 60°C while maintaining the pressure. Then, the pressure is released and the mold is removed to obtain the final insulating heat sink.

[0086] Example 4

[0087] This embodiment provides a method for preparing the insulating heat dissipation plate for the upper pressure plate 211 and the lower pressure plate 212 in Embodiment 1 above, including the following steps:

[0088] Step S1: Weigh out 15% polyvinylidene fluoride, 15% hexagonal boron nitride, 2% SiO2-coated multi-walled carbon nanotubes, 1% silane coupling agent, 25% spherical aluminum nitride, and the balance is N-methylpyrrolidone according to the mass ratio.

[0089] Hexagonal boron nitride, spherical aluminum nitride, and SiO2 were coated onto multi-walled carbon nanotubes, placed in a flask, and an appropriate amount of anhydrous ethanol was added and ultrasonically dispersed.

[0090] Step S2: Dilute the weighed silane coupling agent with ethanol, and add it dropwise to the packing suspension while stirring. Reflux the system at 70°C for 2 hours to complete the chemical modification of the packing surface. After the reaction is complete, filter and wash with ethanol to obtain a filter cake. Grind the filter cake to obtain the modified composite thermally conductive packing. Specifically, dry the filter cake in a vacuum drying oven at 80°C for 6 hours. Grind the modified composite packing and sieve it (200 mesh) to obtain the modified composite thermally conductive packing.

[0091] Add N-methylpyrrolidone to a container equipped with a stirrer. Start stirring and slowly add polyvinylidene fluoride powder. Continue stirring in a 60°C water bath until the polyvinylidene fluoride powder is completely dissolved to form a transparent liquid. Then, gradually and slowly add all the modified composite thermally conductive filler obtained in the first step to the transparent liquid. Use a planetary centrifuge to stir the transparent liquid under vacuum in revolution / rotation mode for 15 minutes to completely break up agglomerates and obtain an extremely uniform slurry.

[0092] Step S3: Apply the homogenized slurry to a smooth substrate (such as glass or release film) using a doctor blade coater. The doctor blade gap should be 1.5 times the thickness of the target insulating heat sink. Then transfer the coated wet film along with the substrate to a ventilated drying oven and let it stand horizontally at 80°C for 2 hours to allow most of the N-methylpyrrolidone to evaporate gently, resulting in a preform with a certain strength.

[0093] Step S4: Carefully peel the dried preform from the substrate and cut it to the target size. Place the cut preform into the mold of a preheated flatbed hot press. The temperature of the flatbed hot press is 190℃, the pressure is 15MPa, and the hot pressing time is 120min.

[0094] After the pressure holding period, the temperature is cooled to below 60°C while maintaining the pressure. Then, the pressure is released and the mold is removed to obtain the final insulating heat sink.

[0095] According to the national standard GB / T 10297-2015 "Determination of Thermal Conductivity of Non-metallic Solid Materials - Hot Wire Method" and the general test specifications for insulating materials for power electronic devices, the heat dissipation performance of the insulating heat sinks prepared in Examples 2 to 4 was tested. The specific method and procedure are as follows:

[0096] I. Sample Preparation and Treatment

[0097] Three standard samples with dimensions of 50mm × 50mm × original thickness were cut from the finished insulating heat dissipation plates prepared in Examples 2, 3, and 4, respectively.

[0098] Commercially available silicone-based thermal pads (thermal conductivity 1.5 W / (m·K)) and alumina-filled silicone pads (thermal conductivity 3.0 W / (m·K)) were selected as comparative materials.

[0099] All samples were conditioned for 24 hours in a standard environment of (23±2)℃ and 50%±5% relative humidity before testing.

[0100] II. Test Conditions and Methods

[0101] Test environment: Temperature (23±2)℃, humidity ≤70%;

[0102] A Hot Disk TPS2500S thermal constant analyzer equipped with a Kapton thin-film sensor (radius 6.403 mm) was used; the transient planar heat source method was employed, with a test power of 0.1 W and a test time of 10 s.

[0103] Each sample was measured at three different locations, and the average value was taken as the final result. The results are recorded in Table 1.

[0104] Table 1. Heat dissipation performance of the insulating heat sinks prepared in Examples 2-4

[0105]

[0106] As shown in Table 1, the insulating heat sinks of Examples 2-4 exhibit excellent thermal conductivity, with thermal conductivity not less than 5.8 W / (m·K), significantly higher than that of commercially available silicon-based gaskets and alumina-filled gaskets. Furthermore, the thermal resistance of all the sample examples is significantly lower than that of the comparative materials, demonstrating superior heat transfer efficiency.

[0107] Standardized heat dissipation performance tests show that the insulating heat sinks prepared in Examples 2-4 have significantly better thermal conductivity than traditional thermal conductive materials, making them suitable for applications with stringent heat dissipation requirements, such as double-sided heat dissipation MOS chip packaging.

[0108] In this invention, a flexible matrix framework is first constructed using polyvinylidene fluoride (PVDF). A synergistic thermally conductive network is formed by the two-dimensional sheet structure of hexagonal boron nitride and the three-dimensional filling properties of spherical aluminum nitride. Crucially, SiO2-coated multi-walled carbon nanotubes are introduced as nano-bridging units. Their unique one-dimensional tubular structure effectively connects the micron-sized filler gaps, significantly improving the vertical thermal conductivity. Simultaneously, the surface modification effect of a silane coupling agent greatly reduces the interfacial thermal resistance between the filler and the matrix, while precise control of the N-methylpyrrolidone solvent ensures the uniform distribution and ideal rheological properties of each component. This multi-scale, multi-dimensional filler compounding strategy fundamentally overcomes the technical bottlenecks of traditional polymer-based insulating materials, such as discontinuous thermal conduction paths and high interfacial thermal resistance caused by the single filler morphology.

[0109] Furthermore, precise control of component structure and performance is achieved through optimized material pretreatment and molding processes: First, a solvent-assisted surface modification process is used to uniformly coat all inorganic fillers, ensuring interfacial compatibility. In the molding stage, an innovative process route combining cast coating and stepped thermo-pressing curing is adopted. Precise pre-setting of the preform thickness is achieved through precisely controlled scraper gaps. Then, through a staged temperature-pressure coupling process, the solvent is gently removed, the polymer matrix is ​​melt-wetted, and the three-dimensional thermally conductive network is reconstructed and cured sequentially. This series of process innovations effectively eliminates internal porosity, interfacial defects, and stress concentration in the material, producing an advanced insulating heat sink that provides an ideal packaging solution for double-sided heat dissipation of high-power-density MOS chips.

[0110] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A double-sided heat-dissipating MOS chip stacked package structure, characterized in that: The package (1) and the stacked component (2) installed in the package (1) are included; The package (1) includes a lower plastic package (11) and an upper plastic package (12), the lower plastic package (11) and the upper plastic package (12) are snap-fitted to form a hollow box structure, the first heat sink is arranged in the lower plastic package (11), the top end of the first heat sink is fixedly connected with a silicone grease heat conduction structure in a symmetrical manner, the second heat sink is arranged in the upper plastic package (12), and the bottom end of the second heat sink is fixedly connected with a metal heat conduction structure in a symmetrical manner; The stacked component (2) includes a plurality of stacked and arranged press-over structures (21) and a plurality of pins (22) which are clamped and installed on both sides of the press-over structure (21), the press-over structure (21) is located in the box structure, and one end of the pin (22) penetrates through the side wall of the box structure; The top end of the silicone grease heat conduction structure penetrates through the press-over structure (21), and the bottom end of the metal heat conduction structure is inserted into the silicone grease heat conduction structure; When the bottom end of the upper plastic package (12) is snap-fitted with the outer wall of the lower plastic package (11) to form a complete box structure, under the extrusion of the metal heat conduction structure, the silicone grease heat conduction structure rotates to expose a gap for the flow of heat-conducting silicone grease, and at the same time, the heat-conducting silicone grease flows under the extrusion of the metal heat conduction structure to fill the gaps between the metal heat conduction structure and the silicone grease heat conduction structure and between the silicone grease heat conduction structure and the press-over structure (21).

2. The double-sided heat dissipating MOS chip stacked package structure of claim 1, wherein: The press-over structure (21) includes an upper press-over plate (211), a lower press-over plate (212) and a chip (213), the upper press-over plate (211) and the lower press-over plate (212) are both insulating heat dissipation plates, and the contact surfaces of the upper press-over plate (211) and the lower press-over plate (212) are provided with grooves matching the shape of the chip (213), and the chip (213) is located in the groove; The left and right ends of the upper press-over plate (211) and the lower press-over plate (212) are both provided with through holes (214) for the silicone grease heat conduction structure to penetrate through, and the front and rear ends of the upper press-over plate (211) and the lower press-over plate (212) are both provided with plate grooves (215) in communication with the grooves, and the connecting end of the pin (22) is clamped and fitted with the plate groove (215).

3. The double-sided heat dissipating MOS chip stacked package structure of claim 2, wherein: The lower plastic package (11) includes a lower plastic package shell (111), the lower plastic package shell (111) is a box structure with a top surface exposed, the first heat sink includes a lower uniform heat plate (112) embedded in the bottom of the lower plastic package shell (111), the two ends of the lower uniform heat plate (112) are bevels, and the bevel end of the lower uniform heat plate (112) penetrates through the side of the lower plastic package shell (111); The upper plastic package (12) includes an upper plastic package shell (121), the upper plastic package shell (121) is a box structure with a bottom surface exposed, the second heat sink includes an upper uniform heat plate (122) embedded in the top of the upper plastic package shell (121), and the surface of the upper uniform heat plate (122) is provided with heat dissipation fins, and the left and right ends of the bottom of the upper plastic package shell (121) are fixedly connected with hook edges (1211) in correspondence, and the hook edges (1211) are clamped and fitted with the bevel end of the lower uniform heat plate (112); The side walls of the lower plastic package shell (111) and the upper plastic package shell (121) are both provided with apertures for the pins (22) to penetrate through.

4. The double-sided heat dissipating MOS chip stack package structure of claim 3, wherein: The silicon grease heat conduction structure comprises a heat transfer shaft (1121) and a sleeve sleeve (1122) sleeved on the periphery of the heat transfer shaft (1121), the bottom of the heat transfer shaft (1121) is provided with a first through hole (1123) for passing the heat conduction silicon grease, and the bottom of the sleeve sleeve (1122) is provided with a second through hole (1124), and the inner wall of the sleeve sleeve (1122) is provided with an arc edge (1125) at the top. The metal heat conduction structure comprises a pair of heat transfer rods (1221), the top of the heat transfer rod (1221) is fixedly connected with the upper heat plate (122), and the side wall of the heat transfer rod (1221) is fixedly connected with the side shaft (1222) near the upper heat plate (122).

5. The dual-sided heat dissipating MOS chip stack package structure of claim 2, wherein: The preparation method of the insulating heat dissipation plate comprises the following steps: Step S1: according to the mass ratio, 10-15% of polyvinylidene fluoride, 15-20% of hexagonal boron nitride, 1-2% of SiO2 coated multi-walled carbon nanotube, 1-2% of silane coupling agent, 15-25% of spherical aluminum nitride, and the balance of N-methyl pyrrolidone; The hexagonal boron nitride, spherical aluminum nitride and SiO2 coated multi-walled carbon nanotube are placed in a flask, anhydrous ethanol is added and ultrasonic dispersion is carried out; Step S2: after diluting the weighed silane coupling agent with ethanol, it is added dropwise to the filler suspension under stirring, the system is stirred and refluxed at 70-80℃ for 2h, after completion, it is filtered, washed with ethanol, and the filter cake is obtained, then the filter cake is ground to obtain the modified composite heat conduction filler; In a container with a stirrer, N-methyl pyrrolidone is added. Start stirring, add polyvinylidene fluoride powder, continuously stir in a 60℃ water bath, form a transparent glue liquid, then add the modified composite heat conduction filler to the transparent glue liquid, and stir to obtain a slurry; Step S3: the slurry is coated on the substrate using a doctor blade coater, and then the coated wet film is transferred to a ventilated drying oven together with the substrate, and the embryo is formed after drying; Step S4: carefully peel the dried embryo from the substrate, and cut according to the target size. Put the cut embryo into the mold of the flat plate hot press; After the pressure holding is completed, water is passed to cool to below 60℃ while maintaining the pressure, then the pressure is released and demolded to obtain the final insulating heat dissipation plate.

6. The dual-sided heat dissipating MOS chip stack package structure of claim 5, wherein: In the step S2, the filter cake is dried in a 80℃ vacuum drying oven for 6h. The modified composite filler is ground and sieved to obtain the modified composite heat conduction filler.

7. The double-sided heat dissipating MOS chip stack package structure of claim 5, wherein: In the step S2, the transparent glue liquid is stirred by a planetary centrifugal stirrer in a vacuum condition in a revolution / rotation mode for 10-15min to obtain the slurry.

8. The dual-sided heat dissipating MOS chip stack package structure of claim 5, wherein: In the step S3, the gap of the doctor blade is 1.5-2 times the thickness of the target insulating heat dissipation plate.

9. The double-sided heat dissipating MOS chip stack package structure of claim 5, wherein: In the step S3, horizontally stand still at 60-80℃ for 2-4h to obtain the embryo.

10. The dual-sided heat dissipating MOS chip stack package structure of claim 5, wherein: In the step S4, the temperature of the flat plate hot press is 180-190℃, the pressure is 15-20MPa, and the hot pressing time is 15-20min.

Images