eMMC stacked package structure

Abstract

This invention discloses an eMMC stacked packaging structure, comprising: a packaging substrate, a chip stack disposed on the packaging substrate, a flexible conductive interconnect layer, a dam fixed to the packaging substrate and surrounding the chip stack, and a floating voltage equalization assembly. The flexible conductive interconnect layer includes multiple elastic conductive connection units arranged vertically and an elastic insulating layer covering the elastic conductive connection units. The inner side of the dam has multiple annular support steps corresponding to each chip layer along the height direction. The edges of each chip layer are connected to the corresponding annular support steps through elastic connection structures. The floating voltage equalization assembly is disposed above the chip stack. This reduces packaging stress caused by thermal expansion mismatch under wide temperature environments and improves the connection reliability and long-term operational stability of the eMMC stacked packaging structure under thermal cycling conditions.

Description

Technical Field

[0001] This invention relates to the field of semiconductor chip packaging technology, and more specifically to an eMMC stacked packaging structure. Background Technology

[0002] As memory devices evolve towards higher density, miniaturization, and higher reliability, eMMC (Embedded MultiMedia Card) devices typically employ multi-chip stacked packaging structures to increase storage capacity. However, in wide operating temperature environments (such as -40℃ to 95℃ or even wider), complex thermomechanical stresses can easily arise inside the device due to the mismatch in thermal expansion coefficients of different materials and the spatial constraints of the multi-chip stacked structure.

[0003] Existing technologies typically employ the following methods to improve performance: placing underfill material between chips to alleviate stress concentration; using a rigid dam structure for encapsulation and fixation; and placing a fixing plate on top of the package to enhance structural stability.

[0004] However, the above solutions have the following shortcomings: the underfill structure is difficult to effectively release the three-dimensional coupling stress; the rigid dam structure restricts the chip's lateral deformation capability, which can easily lead to edge stress concentration; the fixed pressure plate cannot adapt to thermal expansion changes under wide temperature conditions, which can easily cause local overpressure or underpressure; and the interlayer electrical connection structure of the chip is prone to fatigue failure during thermal cycling. Summary of the Invention

[0005] The purpose of this invention is to provide an eMMC stacked packaging structure to solve the above-mentioned problems existing in the prior art.

[0006] The present invention solves the above-mentioned technical problems through the following technical solution: An eMMC stacked package structure, comprising: Packaging substrate; A chip stack disposed on the packaging substrate, the chip stack including a controller chip at the bottom and at least one flash memory chip stacked on the controller chip; A flexible conductive interconnect layer is disposed between adjacent chips and between the controller chip and the packaging substrate. The flexible conductive interconnect layer includes a plurality of elastic conductive connection units arranged in a vertical direction and an elastic insulating layer covering the elastic conductive connection units. A dam is fixed to the packaging substrate and surrounds the chip stack. The inner side of the dam is provided with a plurality of annular support steps corresponding to each layer of chips along the height direction. The edges of each layer of chips are respectively connected to the corresponding annular support steps through elastic connection structures. A floating voltage equalization assembly is disposed above the chip stack. The floating voltage equalization assembly includes a voltage equalization plate, a guide assembly, a temperature-responsive elastic support, and a thermally conductive elastic layer. The guide assembly is connected between the voltage equalization plate and the dam. The temperature-responsive elastic support is disposed between the voltage equalization plate and the dam. The thermally conductive elastic layer is disposed on the lower surface of the voltage equalization plate and contacts the top of the chip stack. The guide component limits the vertical movement of the equalizing plate relative to the dam, and the temperature-responsive elastic support drives the equalizing plate to move along the guide component to adjust the pressure applied by the thermally conductive elastic layer to the top of the chip stack. The flexible conductive interconnect layer, the elastic connection structure, and the floating equalizing component respectively adjust the interlayer displacement, lateral displacement, and vertical force of the chip stack.

[0007] Preferably, the guiding assembly includes at least two guide posts and guide holes corresponding to the guide posts. The guide posts are fixedly disposed on the edge of the equalizing plate, and the guide holes are formed on the top of the dam. The guide posts pass through the corresponding guide holes and slide in cooperation with the guide holes to restrict the equalizing plate from moving horizontally and allow the equalizing plate to move vertically.

[0008] Preferably, the temperature-responsive elastic support includes a plurality of bimetallic strips spaced apart circumferentially along the equalizing plate. One end of each bimetallic strip is fixedly connected to the top of the dam, and the other end is fixedly connected to the equalizing plate. When the temperature changes, each bimetallic strip bends and deforms to drive the equalizing plate to move along the guide assembly.

[0009] Preferably, the number of bimetallic strips is three or four, and the multiple bimetallic strips are evenly distributed along the circumference of the pressure equalizing plate so that the pressure equalizing plate is subjected to uniform force.

[0010] Preferably, the floating pressure equalization assembly further includes a support ring located above the pressure equalization plate. A plurality of bimetallic strips are spaced apart circumferentially along the support ring. One end of each bimetallic strip is fixedly connected to the dam, and the other end is fixedly connected to the support ring. The support ring is fixedly connected to the pressure equalization plate and moves synchronously in the vertical direction under the guidance of the guide assembly.

[0011] Preferably, the thermally conductive elastic layer is a thermally conductive buffer layer disposed on the lower surface of the equalizing plate. The thermally conductive elastic layer is made of a thermally conductive elastic material and forms a compressible contact interface between the equalizing plate and the chip stack to buffer the contact stress of the equalizing plate on the chip stack and improve the uniformity of heat conduction.

[0012] Preferably, the elastic connection structure includes a plurality of elastic microbeams formed at the edges of each chip layer and an elastic adhesive layer disposed between the elastic microbeams and the annular support steps of the dam. The elastic microbeams extend along the chip edges and have radial elastic deformation capability to absorb lateral displacement when the chip thermally expands or contracts.

[0013] Preferably, the flexible conductive interconnect layer includes a plurality of elastic conductive connection units, which are arranged vertically and distributed in an array. Each elastic conductive connection unit includes a conductive elastic pillar and an elastic insulating layer covering the outside of the conductive elastic pillar. The conductive elastic pillar can generate elastic deformation when heated or compressed to adapt to the thermal expansion difference between adjacent chips.

[0014] Preferably, the dam is made of a material with high thermal conductivity.

[0015] Preferably, the interior of the dam is provided with a metal heat-conducting channel extending in the height direction and a heat-conducting layer extending in the horizontal direction, and the metal heat-conducting channel is connected to the heat-conducting layer.

[0016] Compared with the prior art, the present invention has the following beneficial effects: By setting flexible conductive interconnect layers between adjacent chips and between the controller chip and the packaging substrate, the elastic conductive connection units and elastic insulating layers absorb the displacement caused by the thermal expansion difference between the layers of the chip stack, reducing stress concentration at the interlayer connection points and improving the reliability of the interlayer electrical connection; by setting a dam with annular support steps around the chip stack and using an elastic connection structure to connect the edges of each chip layer to the corresponding annular support steps, the chips can generate controlled lateral displacement when subjected to thermal expansion or contraction, thereby reducing stress concentration at the chip edges and improving the structural stability of the chip stack; A floating pressure equalization assembly is installed at the top of the dam. A guide assembly limits the vertical movement of the pressure equalization plate, and a temperature-responsive elastic support drives the pressure equalization plate to adjust the pressure applied to the top of the chip stack by the thermally conductive elastic layer. This ensures that the chip stack maintains a relatively uniform vertical force at different operating temperatures, improving the uniformity of force and thermal stability at the top of the chip stack. The flexible conductive interconnect layer, elastic connection structure, and floating pressure equalization assembly coordinately adjust the interlayer displacement, lateral displacement, and vertical force of the chip stack, thereby reducing the packaging stress caused by thermal expansion mismatch under wide temperature conditions and improving the connection reliability and long-term operational stability of the eMMC stacked packaging structure under thermal cycling conditions. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of an eMMC stacked package structure according to a preferred embodiment of the present invention; Figure 2This is a schematic diagram of the eMMC stacked package structure from another angle, representing a preferred embodiment of the present invention. Figure 3 This is a top view of a preferred embodiment of the eMMC stacked package structure of the present invention; Figure 4 This is a schematic diagram of the dam structure of a preferred embodiment of the eMMC stacked package structure of the present invention; Figure 5 This is a schematic diagram of an eMMC stacked package structure according to another preferred embodiment of the present invention.

[0018] Explanation of reference numerals in the attached drawings: packaging substrate 100, controller chip 210, flash memory chip 220, flexible conductive interconnect layer 300, equalizing plate 410, bump 411, thermally conductive elastic layer 420, guide assembly 430, guide post 431, guide hole 432, temperature-responsive elastic support 440, support ring 450, dam 510, annular support step 511, groove 513, elastic adhesive layer 610, elastic microbeam 620. Detailed Implementation

[0019] The present invention will be further illustrated by way of embodiments below, but the present invention is not limited to the scope of the embodiments.

[0020] like Figures 1-4As shown, this embodiment provides an eMMC stacked packaging structure, including: a packaging substrate 100, a chip stack disposed on the packaging substrate 100, a flexible conductive interconnect layer 300, a dam 510 fixed to the packaging substrate 100 and surrounding the chip stack, and a floating voltage equalization component. The chip stack includes a controller chip 210 at the bottom and at least one flash memory chip 220 stacked on the controller chip 210. The flexible conductive interconnect layer 300 is disposed between adjacent chips and between the controller chip 210 and the packaging substrate 100. The flexible conductive interconnect layer 300 includes a plurality of elastic conductive connection units disposed vertically and an elastic insulating layer covering the elastic conductive connection units. The inner side of the dam 510 is provided with a plurality of annular support steps 511 corresponding to each layer of chips along the height direction, and the edges of each layer of chips are respectively connected to the corresponding annular support steps 511 through elastic connection structures. A floating pressure equalization assembly is disposed above the chip stack. The floating pressure equalization assembly includes a pressure equalization plate 410, a guide assembly 430, a temperature-responsive elastic support 440, and a thermally conductive elastic layer 420. The guide assembly 430 connects the pressure equalization plate 410 and the dam 510. The temperature-responsive elastic support 440 is disposed between the pressure equalization plate 410 and the dam 510. The thermally conductive elastic layer 420 is disposed on the lower surface of the pressure equalization plate 410 and contacts the top of the chip stack. The guide assembly 430 limits the vertical movement of the pressure equalization plate 410 relative to the dam 510. The temperature-responsive elastic support 440 drives the pressure equalization plate 410 to move along the guide assembly 430, thereby adjusting the pressure applied by the thermally conductive elastic layer 420 to the top of the chip stack. The flexible conductive interconnect layer 300, the elastic connection structure, and the floating pressure equalization assembly respectively adjust the interlayer displacement, lateral displacement, and vertical force of the chip stack.

[0021] This application provides an eMMC stacked packaging structure. By providing flexible conductive interconnect layers 300 between adjacent chips and between the controller chip 210 and the packaging substrate 100, the flexible conductive connection units and elastic insulating layer absorb displacement caused by thermal expansion differences between the chip stack layers, reducing stress concentration at interlayer connections and improving the reliability of interlayer electrical connections. Furthermore, by providing a dam 510 with annular support steps 511 around the chip stack, and using elastic connection structures to connect the edges of each chip layer to the corresponding annular support steps 511, the edges of each chip layer can generate controlled lateral displacement when subjected to thermal expansion or contraction, thereby reducing stress concentration at the chip edges and improving the structural stability of the chip stack. A floating pressure equalization component is installed at the top of the dam 510. The guide component 430 limits the vertical movement of the pressure equalization plate 410, and the temperature-responsive elastic support component 440 drives the pressure equalization plate 410 to adjust the pressure applied to the top of the chip stack by the thermally conductive elastic layer 420. This ensures that the chip stack can maintain a relatively uniform vertical force at different operating temperatures, improving the uniformity of force and thermal stability at the top of the chip stack. The flexible conductive interconnect layer 300, the elastic connection structure, and the floating pressure equalization component coordinately adjust the interlayer displacement, lateral displacement, and vertical force of the chip stack, thereby reducing the packaging stress caused by thermal expansion mismatch under wide temperature conditions and improving the connection reliability and long-term working stability of the eMMC stacked packaging structure under thermal cycling conditions.

[0022] In some embodiments, such as Figure 1 , Figure 3 and Figure 4 As shown, the guide assembly 430 includes at least two guide posts 431 and guide holes 432 corresponding to the guide posts 431. The guide posts 431 are fixedly disposed on the edge of the equalizing plate 410, and the guide holes 432 are formed on the top of the dam 510. The guide posts 431 pass through the corresponding guide holes 432 and slide in cooperation with the guide holes 432 to restrict the equalizing plate 410 from moving horizontally and allow the equalizing plate 410 to move vertically. The dam 510 includes a groove 513, and the guide holes 432 are disposed in the groove 513. The equalizing plate 410 includes outwardly extending protrusions 411, the protrusions 411 corresponding to the position of the groove 513, and the guide posts 431 are disposed at the protrusions 411.

[0023] Through the sliding fit between the guide post 431 and the guide hole 432, while ensuring that the pressure equalizing plate 410 can move freely in the vertical direction, the displacement and tilt of the pressure equalizing plate 410 in the horizontal direction are restricted. This allows the displacement generated by the temperature-responsive elastic support 440 to be stably transmitted to the pressure equalizing plate 410, improving the motion stability and guiding accuracy of the pressure equalizing plate 410 during its movement. It also ensures that the thermally conductive elastic layer 420 maintains stable contact with the top of the chip stack, thereby improving the uniformity of force and thermal stability of the top of the chip stack.

[0024] In some embodiments, such as Figure 2 As shown, the temperature-responsive elastic support 440 includes a plurality of bimetallic strips spaced apart circumferentially along the pressure equalization plate 410. One end of each bimetallic strip is fixedly connected to the top of the dam 510, and the other end is fixedly connected to the pressure equalization plate 410. When the temperature changes, each bimetallic strip bends and deforms to drive the pressure equalization plate 410 to move along the guide assembly 430.

[0025] By setting multiple bimetallic strips distributed circumferentially along the pressure equalizing plate 410, the bending deformation of the bimetallic strips during temperature changes drives the pressure equalizing plate 410 to move vertically along the guide assembly 430. This allows the pressure applied by the thermally conductive elastic layer 420 to the top of the chip stack to be adaptively adjusted according to the operating temperature, thereby reducing the vertical stress caused by thermal expansion mismatch under different temperature conditions, improving the uniformity of the force on the top of the chip stack, and helping to maintain a stable contact state between the chip stack and the thermally conductive elastic layer 420, thus improving the reliability of the packaging structure under wide temperature conditions.

[0026] In some embodiments, the bimetallic strip includes a first metal layer and a second metal layer, which are compositely connected along the thickness direction, and the coefficient of thermal expansion of the first metal layer is greater than that of the second metal layer. When the ambient temperature changes, due to the difference in thermal expansion between the first and second metal layers, the bimetallic strip undergoes reversible bending deformation and generates displacement in the vertical direction, thereby driving the equalizing plate 410 to move. Specifically, when the temperature rises, each bimetallic strip bends away from the chip stack, causing the equalizing plate 410 to move upward; when the temperature decreases, each bimetallic strip bends towards the chip stack, causing the equalizing plate 410 to move downward.

[0027] The first metal layer and the second metal layer are made of metal materials with different coefficients of thermal expansion. The first metal layer can be made of copper, copper alloy, aluminum or aluminum alloy, and the second metal layer can be made of stainless steel, Invar alloy, Kovar alloy or nickel-iron alloy.

[0028] In some embodiments, the bimetallic strip is in the form of a strip, an arc, or a fan shape, with a thickness of 0.05 to 0.50 mm, a width of 0.5 to 5 mm, and a length set according to the size of the equalizing plate 410 to meet the displacement requirements of the equalizing plate 410 within a preset temperature range.

[0029] In some embodiments, multiple bimetallic strips are evenly distributed around the circumference of the equalizing plate 410, and the included angle between adjacent bimetallic strips is equal, so that the driving force generated by each bimetallic strip is evenly applied to the equalizing plate 410, thereby improving the uniformity of force on the equalizing plate 410 during movement and reducing the possibility of the equalizing plate 410 tilting.

[0030] In some embodiments, the number of bimetallic strips is three or four, and the multiple bimetallic strips are evenly distributed along the circumference of the pressure equalization plate 410 to ensure that the pressure equalization plate 410 is subjected to uniform force. The driving force generated by each bimetallic strip when the temperature changes can act evenly on the pressure equalization plate 410, reducing the possibility of the pressure equalization plate 410 shifting or tilting during movement, and cooperating with the guide assembly 430 to improve the stability of the pressure equalization plate 410 moving in the vertical direction, so that the thermally conductive elastic layer 420 can apply pressure to the top of the chip stack more evenly.

[0031] In some embodiments, such as Figure 5 As shown, the floating pressure equalization assembly also includes a support ring 450, which is located above the pressure equalization plate 410. Multiple bimetallic strips are spaced apart along the circumference of the support ring 450. One end of each bimetallic strip is fixedly connected to the dam 510, and the other end is fixedly connected to the support ring 450. The support ring 450 is fixedly connected to the pressure equalization plate 410 and moves synchronously in the vertical direction under the guidance of the guide assembly 430. By setting the support ring 450, a force transmission path of "bimetallic sheet - support ring 450 - pressure equalizing plate 410" is formed between multiple bimetallic sheets and the pressure equalizing plate 410. This allows the displacement and load generated by the multiple bimetallic sheets to be balanced by the support ring 450 before being transmitted to the pressure equalizing plate 410. This reduces the impact of local concentrated loads on the pressure equalizing plate 410, improves the synchronicity and stability of the pressure equalizing plate 410's vertical movement, and facilitates the thermally conductive elastic layer 420 to apply more uniform pressure to the chip stack, thereby further improving the stress uniformity and long-term reliability of the eMMC stacked package structure under thermal cycling conditions.

[0032] In some embodiments, the thermally conductive elastic layer 420 is a thermally conductive buffer layer disposed on the lower surface of the equalizing plate 410. The thermally conductive elastic layer 420 is made of a thermally conductive elastic material and forms a compressible contact interface between the equalizing plate 410 and the chip stack to buffer the contact stress of the equalizing plate 410 on the chip stack and improve the uniformity of heat conduction.

[0033] By setting a thermally conductive elastic layer 420, a contact interface with both thermal conductivity and elastic buffering properties is formed between the equalizing plate 410 and the chip stack. This allows the thermally conductive elastic layer 420 to absorb the local load applied by the equalizing plate 410 while maintaining a stable thermal conduction path, reducing the contact stress concentration at the top of the chip stack, lowering the interface thermal resistance, and improving the heat transfer efficiency between the chip stack and the equalizing plate 410. This further improves the heat dissipation uniformity, thermal cycling reliability, and long-term operational stability of the eMMC stacked package structure.

[0034] In some embodiments, the thermally conductive elastic layer 420 includes a thermally conductive elastic matrix and thermally conductive fillers dispersed within the thermally conductive elastic matrix. The thermally conductive fillers are one or more of metal particles, ceramic particles, graphite particles, or graphene, and the thermally conductive fillers form a thermally conductive network within the thermally conductive elastic matrix.

[0035] In some embodiments, the thermally conductive elastic layer 420 includes an elastic substrate layer and a plurality of thermally conductive support pillars disposed within the elastic substrate layer. The plurality of thermally conductive support pillars extend along the thickness direction and are spaced apart. The upper and lower ends of the thermally conductive support pillars are in contact with the equalizing plate 410 and the chip stack, respectively, to form a plurality of thermally conductive pathways extending along the thickness direction. By providing a plurality of thermally conductive support pillars extending along the thickness direction, a plurality of thermally conductive pathways are formed inside the thermally conductive elastic layer 420, allowing heat to be quickly transferred from the chip stack to the equalizing plate 410. At the same time, the elastic substrate layer can undergo elastic deformation between the thermally conductive support pillars to buffer the contact pressure applied by the equalizing plate 410, thereby taking into account both thermal conductivity and buffering performance.

[0036] In some embodiments, the thermally conductive elastic layer 420 includes a first thermally conductive layer, a second thermally conductive layer and a third thermally conductive layer disposed sequentially along the thickness direction, wherein the elastic modulus of the first thermally conductive layer, the second thermally conductive layer and the third thermally conductive layer decreases sequentially.

[0037] In some embodiments, the thermally conductive elastic layer 420 forms a plurality of spaced elastic micro-protrusions on the side facing the chip stack. Each elastic micro-protrusion undergoes compression deformation during the pressing process of the equalizing plate 410 to adapt to the local height difference at the top of the chip stack.

[0038] In some embodiments, the bimetallic strip has a preset initial bending amount or preload in the assembled state, so that the thermally conductive elastic layer 420 maintains a preset contact pressure with the chip stack at room temperature. When the operating temperature changes, the bimetallic strip undergoes further bending deformation based on the initial bending amount to adjust the pressure applied to the top of the chip stack by the pressure equalizing plate 410.

[0039] In some embodiments, such as Figure 1As shown, the elastic connection structure includes multiple elastic microbeams 620 formed on the edges of each chip layer and an elastic adhesive layer 610 disposed between the elastic microbeams 620 and the annular support step 511 of the dam 510. The elastic microbeams 620 extend along the chip edge and have radial elastic deformation capability to absorb lateral displacement when the chip thermally expands or contracts.

[0040] The flexible lateral support structure is formed between the chip stack and the dam 510 through the cooperation of the elastic microbeam 620 and the elastic adhesive layer 610. The elastic microbeam 620 absorbs the lateral displacement of the chip edge through elastic bending, and the elastic adhesive layer 610 buffers the load transmitted by the elastic microbeam 620 through elastic shear deformation. The thermal stress generated at the chip edge is released step by step along the “chip - elastic microbeam 620 - elastic adhesive layer 610 - annular support step 511”, which reduces the local stress concentration at the chip edge and improves the uniformity of lateral force on the chip stack. This further improves the structural stability and long-term reliability of the eMMC stacked packaging structure under thermal cycling conditions.

[0041] In some embodiments, the flexible conductive interconnect layer 300 includes a plurality of elastic conductive connection units, which are arranged vertically and distributed in an array. Each elastic conductive connection unit includes a conductive elastic pillar and an elastic insulating layer covering the outside of the conductive elastic pillar. The conductive elastic pillar can generate elastic deformation when heated or compressed to adapt to the thermal expansion difference between adjacent chips.

[0042] A flexible electrical connection structure is formed between adjacent chips by multiple arrayed elastic conductive interconnect units. The conductive elastic pillars maintain a stable electrical connection while compensating for interlayer displacement between adjacent chips through elastic deformation, reducing mechanical stress caused by thermal expansion mismatch. An elastic insulating layer covers the outside of the conductive elastic pillars, providing electrical insulation while further buffering the contact load between the conductive elastic pillars and adjacent chips through its own elastic deformation. This allows interlayer stress to be gradually released along the conductive elastic pillars and the elastic insulating layer, thereby improving the adaptability of the flexible conductive interconnect layer 300 to interlayer displacement, reducing the risk of fatigue failure of the interlayer interconnect structure, and further improving the electrical connection reliability and long-term working stability of the eMMC stacked package structure under thermal cycling conditions.

[0043] In some embodiments, the conductive elastic pillars may adopt a spiral, corrugated, mesh, or porous elastic structure to improve axial compression performance; the elastic insulating layer may be formed of silicone rubber, polyurethane, polyimide elastic material, or other polymer materials with insulating properties and elastic deformation capabilities, and together with the conductive elastic pillars, constitute a flexible conductive connection unit.

[0044] In some embodiments, the dam 510 is made of a material with high thermal conductivity. The dam 510 is made of a ceramic material or a metal alloy material, wherein the ceramic material includes aluminum nitride, silicon nitride, or silicon carbide, and the metal alloy material includes a molybdenum-copper alloy or a Kovar alloy.

[0045] In some embodiments, the interior of the dam 510 is provided with a metal heat-conducting channel extending in the height direction and a heat-conducting layer extending in the horizontal direction. The metal heat-conducting channel and the heat-conducting layer are connected to form a heat conduction path between the chip stack and the external environment, and improve the heat dissipation uniformity of the chip stack.

[0046] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. An eMMC stacked package structure, characterized in that, include: Packaging substrate; A chip stack disposed on the packaging substrate, the chip stack including a controller chip at the bottom and at least one flash memory chip stacked on the controller chip; A flexible conductive interconnect layer is disposed between adjacent chips and between the controller chip and the packaging substrate. The flexible conductive interconnect layer includes a plurality of elastic conductive connection units arranged in a vertical direction and an elastic insulating layer covering the elastic conductive connection units. A dam is fixed to the packaging substrate and surrounds the chip stack. The inner side of the dam is provided with a plurality of annular support steps corresponding to each layer of chips along the height direction. The edges of each layer of chips are respectively connected to the corresponding annular support steps through elastic connection structures. A floating voltage equalization assembly is disposed above the chip stack. The floating voltage equalization assembly includes a voltage equalization plate, a guide assembly, a temperature-responsive elastic support, and a thermally conductive elastic layer. The guide assembly is connected between the voltage equalization plate and the dam. The temperature-responsive elastic support is disposed between the voltage equalization plate and the dam. The thermally conductive elastic layer is disposed on the lower surface of the voltage equalization plate and contacts the top of the chip stack. The guide component limits the vertical movement of the equalizing plate relative to the dam, and the temperature-responsive elastic support drives the equalizing plate to move along the guide component to adjust the pressure applied by the thermally conductive elastic layer to the top of the chip stack. The flexible conductive interconnect layer, the elastic connection structure, and the floating equalizing component respectively adjust the interlayer displacement, lateral displacement, and vertical force of the chip stack.

2. The eMMC stacked packaging structure according to claim 1, characterized in that, The guiding assembly includes at least two guide posts and guide holes corresponding to the guide posts. The guide posts are fixedly disposed on the edge of the pressure equalization plate, and the guide holes are formed on the top of the dam. The guide posts pass through the corresponding guide holes and slide in cooperation with the guide holes to restrict the pressure equalization plate from moving horizontally and allow the pressure equalization plate to move vertically.

3. The eMMC stacked packaging structure according to claim 1, characterized in that, The temperature-responsive elastic support includes a plurality of bimetallic strips spaced apart circumferentially along the pressure equalization plate. One end of each bimetallic strip is fixedly connected to the top of the dam, and the other end is fixedly connected to the pressure equalization plate. When the temperature changes, each bimetallic strip bends and deforms to drive the pressure equalization plate to move along the guide assembly.

4. The eMMC stacked packaging structure according to claim 3, characterized in that, The number of bimetallic strips is three or four, and the multiple bimetallic strips are evenly distributed along the circumference of the pressure equalizing plate so that the pressure equalizing plate is subjected to uniform force.

5. The eMMC stacked packaging structure according to claim 3, characterized in that, The floating pressure equalization assembly also includes a support ring located above the pressure equalization plate. A plurality of bimetallic strips are spaced apart circumferentially along the support ring. One end of each bimetallic strip is fixedly connected to the dam, and the other end is fixedly connected to the support ring. The support ring is fixedly connected to the pressure equalization plate and moves synchronously in the vertical direction under the guidance of the guide assembly.

6. The eMMC stacked packaging structure according to claim 1, characterized in that, The thermally conductive elastic layer is a thermally conductive buffer layer disposed on the lower surface of the equalizing plate. The thermally conductive elastic layer is made of thermally conductive elastic material and forms a compressible contact interface between the equalizing plate and the chip stack to buffer the contact stress of the equalizing plate on the chip stack and improve the uniformity of heat conduction.

7. The eMMC stacked packaging structure according to claim 1, characterized in that, The elastic connection structure includes multiple elastic microbeams formed at the edges of each chip layer and an elastic adhesive layer disposed between the elastic microbeams and the annular support steps of the dam. The elastic microbeams extend along the chip edges and have radial elastic deformation capability to absorb lateral displacement when the chip thermally expands or contracts.

8. The eMMC stacked packaging structure according to claim 1, characterized in that, The flexible conductive interconnect layer includes multiple elastic conductive connection units, which are arranged vertically and distributed in an array. Each elastic conductive connection unit includes a conductive elastic pillar and an elastic insulating layer covering the outside of the conductive elastic pillar. The conductive elastic pillar can generate elastic deformation when heated or compressed to adapt to the thermal expansion difference between adjacent chips.

9. The eMMC stacked packaging structure according to claim 1, characterized in that, The dam is made of a material with high thermal conductivity.

10. The eMMC stacked packaging structure according to claim 1 or 9, characterized in that, The dam is equipped with a metal heat-conducting channel extending along the height direction and a heat-conducting layer extending along the horizontal direction, and the metal heat-conducting channel is connected to the heat-conducting layer.

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