Semiconductor packaging structure and packaging method thereof

Abstract

The invention relates to a semiconductor packaging structure and a packaging method thereof, and belongs to the technical field of semiconductor devices.The semiconductor packaging structure comprises a substrate, a chip, a radiator and a packaging shell, and further comprises an alloy needle matrix arranged below the radiator and a heated self-deformation fin arranged between the upper surface of the chip and the packaging shell; needle bodies of the alloy needle matrixes penetrate through the through holes in the substrate, needle tips of the alloy needle matrixes directly make contact with the back faces of the chips through the heat conduction springs, the heated self-deformation fins are unfolded through heating and abut against the top of the radiator, a double-channel vertical heat dissipation system is constructed, heat conduction paths from the chips to the radiator are directly broken through, and the double paths work in parallel. It is ensured that heat is vertically transmitted to the radiator through the shortest path, loss of traditional transverse heat diffusion is avoided, and the problems of thermal resistance accumulation caused by series connection of multiple layers of media, interface shear stress and micro cracks caused by mismatch of material thermal expansion coefficients of an existing semiconductor packaging structure are solved. And the problems of heat dissipation path failure and local high temperature of the chip caused thereby are solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor devices, and in particular relates to a semiconductor packaging structure and a packaging method thereof. Background Art

[0002] In current semiconductor devices, the heat dissipation path of the semiconductor device packaging structure usually adopts a vertical stacked heat conduction design. The heat generated by the chip needs to pass through the solder joint layer, organic substrate, and thermal interface material layer in sequence before finally reaching the external heat sink. Although this multi-layer dielectric series structure can achieve basic heat dissipation functions, each layer of material interface will introduce additional thermal resistance. Especially in high-power chip packaging, when heat passes through materials with different physical properties, the attenuation of the thermal conductivity efficiency of each layer forms progressive heat dissipation, resulting in a significant temperature rise before the heat flow reaches the heat sink.

[0003] Existing semiconductor packaging structures have some problems: due to the inherent differences in material thermal expansion characteristics and the physical limitations of multi-level heat conduction, when the chip undergoes repeated power cycles during operation, heterogeneous materials such as silicon chips, metal solders, and organic substrates generate shear stress under the alternating temperature field due to the mismatch in thermal expansion coefficients. This stress continuously acts on the interfaces of each layer, leading to the formation of microcracks. The cracks not only weaken the structural integrity, but also form air gap-type thermal barriers at the interfaces, causing the thermal resistance to increase nonlinearly. Ultimately, the heat in the core area of ​​the chip cannot be dissipated in time, forming a local high-temperature zone, causing the actual efficiency of the heat dissipation path to be far lower than the theoretical design value. In this regard, a semiconductor packaging structure and packaging method are proposed. Summary of the Invention

[0004] In order to solve the problems of thermal resistance accumulation caused by the series connection of multiple layers of dielectrics in existing semiconductor packaging structures, interface shear stress and microcracks caused by material thermal expansion coefficient mismatch, and the resulting heat dissipation path failure and local high temperature of the chip, the present invention provides a semiconductor packaging structure and a packaging method thereof.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A semiconductor packaging structure includes a substrate, a chip, a heat sink, and a packaging shell. The chip is arranged on the upper surface of the substrate, the heat sink is arranged below the substrate, the packaging shell covers the side walls of the chip and the upper surface of the substrate, and the bottom of the heat sink is exposed. It also includes an alloy needle matrix arranged below the heat sink and heat-sensitive self-deformed fins arranged between the upper surface of the chip and the packaging shell. The needle bodies of the alloy needle matrix pass through the through holes on the substrate, and the needle tips of the alloy needle matrix directly contact the back side of the chip through thermal springs to form a first heat dissipation path. The heat-sensitive self-deformed fins expand when heated and abut the top of the heat sink to form a second heat dissipation path. The alloy needle matrix and the heat-sensitive self-deformed fins form a dual-channel vertical heat dissipation system, so that heat is directly transferred from the chip to the heat sink.

[0007] As a further solution of the present invention, the alloy needle matrix is ​​integrated at the bottom of the radiator. The alloy needles of the alloy needle matrix are tungsten-copper alloy needles. The diameter of the tungsten-copper alloy needles is 0.4mm-0.6mm, and the distance between adjacent tungsten-copper alloy needles is 1.1mm-1.3mm.

[0008] As a further solution of the present invention, the thermally conductive spring is a beryllium copper spring.

[0009] As a further solution of the present invention, the heat-induced self-deforming fin is a folded copper-nickel alloy micro-fin, and the thickness of the folded copper-nickel alloy micro-fin is 49 μm-51 μm, and the unfolded height is 1.1 mm-1.3 mm.

[0010] As a further solution of the present invention, a closed vortex cavity is provided on the top of the packaging shell, a low melting point alloy is provided inside the packaging shell at the closed vortex cavity, and a piezoelectric ceramic vibrator is connected to the bottom of the closed vortex cavity.

[0011] As a further solution of the present invention, the low melting point alloy is a gallium indium tin alloy.

[0012] A semiconductor packaging method comprises the following steps:

[0013] S1: Flip-chip soldering the chip to the upper surface of the substrate to form an electrical connection, install a spring sleeve in the through hole on the substrate, and set a conical buffer head and a cross-shaped elastic claw buckle on the top and bottom of the spring sleeve respectively to absorb the residual stress of welding;

[0014] S2: Pre-install a tungsten-copper alloy needle matrix on the bottom of the heat sink, allowing the alloy needles to penetrate the preset through-holes in the substrate and contact the back of the chip through beryllium copper springs. A spherical hinge joint is machined at the end of the alloy needle body, so that the spherical hinge joint forms a universal contact with the conical buffer head in S1. Then, a guide rail is set on the edge of the heat sink, and a slider that matches the guide rail is installed on the substrate. The slider is rigidly connected to the tungsten-copper alloy needle matrix through an L-shaped force transmission arm to ensure vertical displacement of the alloy needle body during thermal expansion;

[0015] S3: Cover the chip with folded copper-nickel alloy micro fins, inject a molded package shell, cover the chip sidewalls and the upper surface of the substrate, and reserve space for the fins to move. Set a fusible space bracket around the fins, set a spiral compression spring on the top of the bracket, and set a tapered positioning pin at the bottom of the bracket. After the package shell is solidified, heat and melt the bracket, release the spiral compression spring, and push the fin to a preset angle.

[0016] S4: Assemble the radiator under the base plate, seal the needle through-hole, adjust the fin expansion direction toward the top of the radiator to form a dual heat dissipation channel, set ball ejector pins at the end of the fins, and process V-shaped guide grooves on the top of the radiator. The V-shaped guide grooves cooperate with the ball ejector pins at the end of the fins. Install a corrugated gasket between the base plate and the radiator. The gasket edge has a ratchet locking ring. When the locking ring is tightened, the corrugated gasket compresses the driving connecting rod mechanism to adjust the fin inclination angle;

[0017] S5: A closed vortex cavity is formed on the top of the packaging shell, a low-melting-point alloy is injected into the cavity and a piezoelectric ceramic vibrator is connected. A multi-layer metal sealing ring is set at the bottom of the cavity, and liquid metal is filled between the rings. The piezoelectric ceramic vibrator is crimped to the sealing ring through a butterfly spring group, and a centrifugal counterweight is installed on the top of the cavity.

[0018] As a further solution of the present invention, the cross-shaped elastic claw buckle of the spring sleeve in step S1 expands radially during thermal expansion, and the expansion amount is converted into vertical displacement compensation via the guide rail.

[0019] As a further solution of the present invention, in step S3, the conical positioning pin of the fusible space bracket is linked to the L-shaped force transmission arm, and after the bracket is melted, the spiral compression spring pushes the ball ejector pin into the V-shaped guide groove.

[0020] As a further solution of the present invention, the compression stroke of the corrugated gasket in step S4 drives the ratchet locking ring to rotate through the connecting rod mechanism, and synchronously adjusts the position of the fin ball ejector.

[0021] The beneficial effects of the present invention are:

[0022] The present invention directly opens up a heat conduction path from the chip to the radiator by constructing a dual-channel vertical heat dissipation system. The first path: the needle body of the alloy needle matrix passes through the through-hole of the substrate, and the needle tip directly contacts the back of the chip through the thermal conductive spring, so that the heat is transferred from the chip to the thermal conductive spring, then to the alloy needle, and finally to the radiator, skipping the intermediate media such as the solder layer, substrate, and thermal interface material, and eliminating multi-layer thermal resistance; the second path: the fin is located between the upper surface of the chip and the packaging shell. When heated, it automatically expands and abuts the top of the radiator, forming an auxiliary vertical channel from the chip to the fin and then to the radiator, further diverting heat; the dual paths work in parallel to ensure that heat is vertically transferred to the radiator through the shortest path, avoiding the loss of traditional lateral heat diffusion. At the same time, the thermal conductive spring compensates for the thermal expansion difference and maintains stable contact pressure, solving the problems of thermal resistance accumulation caused by the series connection of multiple layers of dielectrics in the existing semiconductor packaging structure, interface shear stress and micro cracks caused by the mismatch of material thermal expansion coefficients, and the resulting heat dissipation path failure and local high temperature of the chip. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] To facilitate understanding by those skilled in the art, the present invention is further described below with reference to the accompanying drawings.

[0024] Figure 1 It is a schematic diagram of the overall structure of the semiconductor packaging structure of the present invention;

[0025] Figure 2 A planar structural diagram of a semiconductor package structure of the present invention;

[0026] Figure 3 This is a schematic diagram of the spring sleeve structure of the present invention;

[0027] Figure 4 This is a schematic diagram of the installation of the guide rail and the slider of the present invention;

[0028] Figure 5 Schematic diagram of the internal structure of the packaging shell of the present invention;

[0029] Figure 6 This is a schematic diagram of the installation of the packaging shell of the present invention;

[0030] Figure 7 This is a flow chart of the semiconductor packaging method of the present invention.

[0031] Legend: 1. Base plate; 11. Through hole; 12. Spring sleeve; 13. Conical buffer head; 14. Cross-shaped elastic claw; 2. Chip; 3. Radiator; 31. Guide rail; 32. Slider; 33. L-shaped force transmission arm; 4. Package shell; 41. Fusible space bracket; 42. Helical compression spring; 43. Conical positioning pin; 5. Alloy needle matrix; 51. Spherical hinge joint; 6. Heat-induced self-deformation fin; 61. Ball ejector pin; 62. V-shaped guide groove; 7. Thermal spring; 8. Enclosed vortex cavity. DETAILED DESCRIPTION

[0032] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the specific implementation methods, structures, features and effects of the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments.

[0033] refer to Figure 1-Figure 7 This embodiment provides a semiconductor packaging structure, including a substrate 1, a chip 2, a heat sink 3, and a package shell 4. The chip 2 is arranged on the upper surface of the substrate 1, and the heat sink 3 is arranged below the substrate 1. The package shell 4 covers the side walls of the chip 2 and the upper surface of the substrate 1, and the bottom of the heat sink 3 is exposed. The structure also includes an alloy needle matrix 5 arranged below the heat sink 3 and heat-sensitive self-deformable fins 6 arranged between the upper surface of the chip 2 and the package shell 4. The needles of the alloy needle matrix 5 pass through the through holes 11 on the substrate 1. The needle tips of the alloy needle matrix 5 directly contact the back of the chip 2 through the thermal spring 7, forming a first heat dissipation path. The heat-sensitive self-deformed fins 6 expand when heated and abut the top of the heat sink 3 to form a second heat dissipation path. The alloy needle matrix 5 and the heat-sensitive self-deformed fins 6 form a dual-channel vertical heat dissipation system, which allows heat to be transferred directly from the chip 2 to the heat sink 3. Among them, the alloy needle matrix 5 directly penetrates the through-hole 11 of the substrate 1 and contacts the back of the chip 2, which can shorten the heat path. The spring then compensates for the mismatch of the thermal expansion coefficient to maintain a constant contact pressure. When the chip 2 heats up, the fins automatically expand and directly connect to the top heat sink 3, so that the heat path skips the substrate 1. After the temperature drops, it automatically folds and is stored, which is compatible with standard package thickness.

[0034] In this embodiment, a dual-channel vertical heat dissipation system is constructed to directly open a heat conduction path from the chip 2 to the heat sink 3. In the first path, the needle body of the alloy needle matrix 5 penetrates the through hole 11 of the substrate 1, and the needle tip directly contacts the back of the chip 2 through the thermally conductive spring 7. This allows heat to flow from the chip 2 to the thermally conductive spring 7, then to the alloy needle, and finally to the heat sink 3, skipping intermediate media such as the solder layer, substrate 1, and thermal interface material, eliminating multi-layer thermal resistance. In the second path, the fin is located between the upper surface of the chip 2 and the package shell 4. When heated, it automatically expands and abuts the top of the heat sink 3, forming an auxiliary vertical channel from the chip 2 to the fin and then to the heat sink 3, further diverting heat. The two paths work in parallel to ensure that heat is transferred vertically to the heat sink 3 via the shortest path, avoiding the loss of traditional lateral heat diffusion. At the same time, the thermally conductive spring 7 compensates for the thermal expansion difference and maintains stable contact pressure. This solves the problems of thermal resistance accumulation caused by the series connection of multiple layers of dielectrics in the existing semiconductor packaging structure, interface shear stress and microcracks caused by material thermal expansion coefficient mismatch, and the resulting heat dissipation path failure and local high temperature of the chip 2.

[0035] It should be further explained that traditional heat dissipation needs to pass through multiple layers of heterogeneous materials, resulting in superimposed thermal resistance. The vertical penetration design of the alloy needle matrix 5 forms a micropore array on the substrate 1, realizing a physical direct connection between the chip 2 and the heat sink 3, shortening the heat conduction distance, and reducing the thermal resistance. The thermal spring 7 acts as a flexible buffer interface to absorb the thermal deformation difference between the chip 2 and the alloy needle; the heat-self-deforming fins 6 fold at low temperatures and unfold at high temperatures, adapting to temperature changes to avoid stress in the rigid structure due to expansion differences, thereby eliminating shear stress, preventing micro cracks and air gap thermal barriers, and directly solving the problem of cracks weakening structural integrity. In addition, the dual channels form a heat flow redundancy mechanism. When the chip 2 is low temperature, it only relies on the basic heat dissipation of the alloy needle matrix 5. When the temperature is high, the fins unfold, additionally increasing the heat dissipation area, reducing the core temperature fluctuation of the chip 2 and avoiding local high temperature areas.

[0036] Since the substrate 1 is usually an organic material and the chip 2 is usually silicon, the thermal expansion coefficients of the substrate 1 and the chip 2 are significantly different. If the diameter of the needle body is too large or the spacing is too small, lateral shear force will be generated between adjacent needle bodies due to displacement and extrusion during thermal expansion, resulting in micro cracks at the edges of the through holes 11 of the substrate 1. To avoid this problem, in one embodiment, the alloy needle matrix 5 is integrated at the bottom of the heat sink 3. The alloy needles of the alloy needle matrix 5 are tungsten-copper alloy needles. The diameter of the tungsten-copper alloy needles is 0.4mm-0.6mm, and the spacing between adjacent tungsten-copper alloy needles is 1.1mm-1.3mm. When the diameter is <0.4mm, the needle body is insufficiently rigid, and the pressure of the thermal spring 7 may cause the needle body to bend, resulting in poor contact; if the diameter is >0.6mm, the through hole 11 occupies too large an area, which weakens the electrical wiring space of the substrate 1. The thermal conductivity of tungsten-copper alloy is much greater than that of traditional solder, and the needles are densely arranged to maximize the heat dissipation contact points. In addition, the spacing of 1.1mm-1.3mm reserves deformation space for thermal expansion to avoid stress accumulation.

[0037] Conventional spring steel undergoes stress relaxation at high temperatures, resulting in insufficient contact pressure between the chip 2 and the needle tip, forming a nanoscale air gap. To avoid contact pressure attenuation during thermal cycling, in one embodiment, the thermally conductive spring 7 is a beryllium copper spring to maintain constant contact pressure and ensure stable interface thermal resistance. High thermal conductivity can also reduce the thermal bottleneck of the spring itself.

[0038] In order to better adapt to the thermal response speed and deformation reliability, in one embodiment, the heat-induced self-deforming fin 6 is a folded copper-nickel alloy microfin. The thickness of the folded copper-nickel alloy microfin is 49μm-51μm, and the unfolded height is 1.1mm-1.3mm. When the thickness is less than 49μm, the fin stiffness is insufficient, and it is squeezed and deformed by the injection pressure of the packaging shell 4 and cannot be unfolded normally. When the thickness is greater than 51μm, the deformation driving force comes from the bimetallic effect of the copper-nickel alloy, which is insufficient to overcome the yield strength of the material, and the unfolded height is limited. The unfolded height of 1.1-1.3mm accurately matches the gap between the chip 2 and the heat sink 3. When it is lower than 1.1mm, the contact is insufficient. When it is higher than 1.3mm, the packaging shell 4 is squeezed, and it can adaptively unfold / fold, with a short response time and an increased effective heat dissipation area at high temperatures; the anti-fatigue properties of the copper-nickel alloy make the cycle life long and can also solve the problem of fracture caused by repeated deformation.

[0039] It is worth mentioning that since the traditional homogeneous heat sink 3 cannot cope with the sudden rise in local temperature of the chip 2, there is a risk of sealing failure. In order to solve this problem, in one embodiment, a closed vortex cavity 8 is provided on the top of the packaging shell 4, and a low-melting-point alloy is provided inside the packaging shell 4 at the closed vortex cavity 8. The bottom of the closed vortex cavity 8 is connected to a piezoelectric ceramic vibrator. The low-melting-point alloy is a gallium indium tin alloy. The vortex cavity drives the low-melting-point alloy to centrifugal motion through piezoelectric vibration, targeting the impact hot spot area, and piezoelectric vibration drives the alloy droplets to impact the hot spot area, so that the local heat transfer coefficient is improved; the gallium indium tin alloy oxide layer automatically repairs micro-leaks, and the multi-layer sealing ring cooperates with the liquid metal filling to block the longitudinal leakage path. The heat of the chip 2 triggers the piezoelectric vibration, which drives the alloy droplets to rotate centrifugally. The droplets hit the hot spot area to enhance convection, thereby improving the heat exchange efficiency. There is no external pump group, and the mechanical vibration can be self-driven, which can cool the moving hot spot in a targeted manner.

[0040] In addition, although the packaging method introduces a dual-channel heat dissipation system and a vortex cavity, there are still some problems in actual implementation. In this regard, a semiconductor packaging method is proposed, including the following steps:

[0041] S1: Because residual stress may be introduced during the welding process, which may increase the risk of interface cracks during thermal expansion, the chip 2 is flip-chip soldered to the upper surface of the substrate 1 to form an electrical connection. A spring sleeve 12 is installed in the through hole 11 on the substrate 1. A conical buffer head 13 and a cross-shaped elastic claw 14 are respectively provided at the top and bottom of the spring sleeve 12 to absorb the residual stress of welding;

[0042] S2: Since thermal expansion can easily cause needle body displacement or uneven spring pressure when the needle body passes through the through hole 11 of the substrate 1, affecting the stability of the first heat dissipation path, the tungsten-copper alloy needle matrix 5 is pre-installed on the bottom of the radiator 3, so that the alloy needle passes through the preset through hole 11 of the substrate 1 and contacts the back of the chip 2 through the beryllium copper spring. A spherical hinge joint 51 is processed at the end of the needle body of the alloy needle so that the spherical hinge joint 51 forms a universal contact with the conical buffer head 13 in S1. Then, a guide rail 31 is set on the edge of the radiator 3, and a slider 32 that matches the guide rail 31 is installed on the substrate 1. The slider 32 is rigidly connected to the tungsten-copper alloy needle matrix 5 through an L-shaped force transmission arm 33 to ensure vertical displacement of the alloy needle body during thermal expansion;

[0043] S3: Since the injection molded shell may squeeze the folded fins when solidifying, limiting their expansion space and causing the second heat dissipation path to fail, a folded copper-nickel alloy micro-fin is covered on the upper surface of the chip 2, and an injection molded packaging shell 4 is used to cover the side walls of the chip 2 and the upper surface of the substrate 1, leaving space for the fins to move. A fusible space bracket 41 is provided around the fin, a spiral compression spring 42 is provided at the top of the bracket, and a conical positioning pin 43 is provided at the bottom of the bracket. After the packaging shell 4 is solidified, the bracket is heated to melt, and the spiral compression spring 42 is released to push the fin to a preset angle; wherein, the fusible space bracket 41 is a low-melting-point thermoplastic polymer, here a polyethylene glycol / PEG-based composite material or a special paraffin-polymer blend, and its melting temperature range is strictly controlled between 80–120°C. In addition, when the fusible bracket is melted, local infrared heating is used to 150°C±10°C for 10 seconds, and the bracket melt is discharged through a 5μm-10μm micro-exhaust channel preset in the packaging shell 4;

[0044] S4: In addition, the gap between the fin and the heat sink 3 may increase due to thermal expansion mismatch, and the dual channels cannot be reliably coupled. Therefore, the heat sink 3 is assembled under the substrate 1, so that the needle body through hole 11 is sealed and fixed, and the expansion direction of the fin is adjusted to the top of the heat sink 3 to form a dual heat dissipation channel. A ball ejector pin 61 is set at the end of the fin, and a V-shaped guide groove 62 is processed on the top of the heat sink 3. The V-shaped guide groove 62 cooperates with the ball ejector pin 61 at the end of the fin. A corrugated gasket is installed between the substrate 1 and the heat sink 3. The edge of the gasket is provided with a ratchet locking ring. When the locking ring is tightened, the corrugated gasket compresses the driving connecting rod mechanism to adjust the fin inclination angle;

[0045] S5: In actual use, the vibrator connection may be loosely sealed, and the low-melting-point alloy may leak under high-frequency vibration, resulting in a decrease in cooling efficiency. To this end, a closed vortex cavity 8 is formed on the top of the packaging shell 4, and a low-melting-point alloy is injected into the cavity and the piezoelectric ceramic vibrator is connected. A multi-layer metal sealing ring is set at the bottom of the cavity, and liquid metal is filled between the rings. The piezoelectric ceramic vibrator is crimped to the sealing ring through a butterfly spring group, and a centrifugal counterweight is installed on the top of the cavity.

[0046] Based on the fact that in traditional packaging, the difference in thermal expansion coefficients between the chip 2 and the substrate 1 induces lateral shear force, resulting in micro cracks at the edge of the through hole 11, in this regard, in one embodiment, the cross-shaped elastic claw 14 of the spring sleeve 12 in step S1 radially expands during thermal expansion, and the expansion amount is converted into vertical displacement compensation through the guide rail 31. The cross-shaped elastic claw 14 adopts an elastic petal structure. During thermal expansion, the claw expands radially to absorb the lateral shear stress between the substrate 1 and the alloy needle. The expansion amount is converted into vertical displacement through the cooperation of the guide rail 31 and the slider 32 system at the edge of the heat sink 3, driving the alloy needle to fine-tune along the axial direction, wherein the claw radially expands to absorb the lateral stress to avoid deformation of the substrate 1, and the guide rail 31 conversion ensures that the stress is converted into vertical displacement rather than lateral damage, and the vertical displacement compensation maintains a constant pressure connection between the needle tip and the chip 2 to prevent contact failure.

[0047] Since the fluid pressure may crush the folded fins during the injection molding of the shell, making it impossible to unfold, in order to avoid this problem, in one embodiment, the conical positioning pin 43 of the fusible space bracket 41 is linked with the L-shaped force transmission arm 33 in step S3. After the bracket is melted, the spiral compression spring 42 pushes the ball ejector pin 61 to embed into the V-shaped guide groove 62. The fusible bracket serves as a temporary support for the fin when the package shell 4 is injection molded. After solidification, it is heated and melted. The conical positioning pin 43 at the bottom of the bracket is mechanically linked with the L-shaped force transmission arm 33 in the contact area of ​​the chip 2 to ensure that the fin is spatially aligned with the alloy needle matrix 5. After the bracket is melted, the spiral compression spring 42 releases the thrust, pushing the ball ejector pin 61 at the end of the fin to embed into the V-shaped guide groove 62 at the top of the heat sink 3. This fusible bracket provides rigid protection during injection molding and is removed after solidification to release the movable space. The horizontal end of the L-shaped force transmission arm 33 is provided with a bevel rack, and the bottom of the conical positioning pin 43 is processed with a bevel gear. Displacement transmission is achieved by meshing the rack and the gear.

[0048] In order to avoid the gap between the chip 2 and the heat sink 3 changing at high temperature, which may cause the fin to be out of contact with the heat sink 3, in one embodiment, the compression stroke of the corrugated gasket in step S4 drives the ratchet locking ring to rotate through the connecting rod mechanism, and synchronously adjusts the position of the fin ball ejector 61. The corrugated gasket is installed between the substrate 1 and the heat sink 3, with a ratchet locking ring on the edge. The connecting rod mechanism includes an active rocker arm, a driven rocker arm and a slide groove. One end of the active rocker arm is hinged to the ratchet locking ring, and the other end is connected to the driven rocker arm through a pin shaft. The end of the driven rocker arm is engaged with the slide groove of the ball ejector 61. The connecting rod mechanism is normally The gauge structure is used to convert the linear displacement of the corrugated gasket into the rotation angle adjustment of the fin. In order to avoid affecting the other structures, it is not drawn in the figure. When the locking ring is tightened, the gasket compression drives the connecting rod, pushing the ball ejector 61 at the end of the fin to slide in the V-shaped guide groove 62, fine-tuning the inclination angle of the fin, and the corrugated gasket compression actively reduces the gap. The connecting rod mechanism adjusts the inclination angle of the fin in real time to maintain abutment. In addition, the ratchet locking ring provides progressive locking, and the connecting rod mechanism converts linear compression into fine-tuning of the fin angle. The corrugated structure compensates for assembly tolerances and thermal deformation to maintain interface pressure.

[0049] The working principle and workflow of the present invention:

[0050] When the semiconductor chip 2 is powered on and generates heat, the heat on its back is directly transferred to the closely contacted tungsten-copper alloy needle matrix 5 through the highly thermally conductive beryllium copper spring. The alloy needle body vertically penetrates the through hole 11 on the substrate 1, efficiently transferring heat to the heat sink 3 below, forming the first heat dissipation path. This path completely skips the intermediate media such as the solder layer, organic substrate 1, and thermal interface material in traditional packaging, significantly shortening the heat conduction distance and eliminating the accumulation of multiple layers of thermal resistance. At the same time, the increase in the surface temperature of the chip 2 activates the folded copper-nickel alloy microfin covering it. The fin uses the bimetallic effect of the copper-nickel alloy to automatically expand and deform when heated. The ball ejector pin 61 installed at its end is precisely embedded in the V-shaped guide groove 62 pre-machined on the top of the heat sink 3, thereby establishing a second heat dissipation path between the top surface of the chip 2 and the top of the heat sink 3. This auxiliary vertical channel further diverts the heat from the chip 2, effectively increasing the heat dissipation surface area. The two paths work in parallel to form a dual-channel vertical heat dissipation system, ensuring that heat is vertically transferred to the radiator 3 via the shortest path and minimum thermal resistance, thus avoiding the efficiency loss caused by traditional lateral heat diffusion.

[0051] During operation, the lateral shear stress generated by the difference in thermal expansion coefficients between the chip 2 and the substrate 1 is absorbed by the cross-shaped elastic claw 14 of the spring sleeve 12 in the through hole 11 of the substrate 1. The radial expansion of the claw is converted into vertical displacement compensation of the alloy needle body along the L-shaped force transmission arm 33 through the sliding system composed of the guide rail 31 on the edge of the heat sink 3 and the slider 32 on the substrate 1, maintaining a constant pressure connection between the needle tip and the back of the chip 2 to prevent contact failure and air gap formation; in the packaging process, when the shell is injection molded, the fusible space bracket 41 temporarily supports and protects the folded fins. After the shell is solidified, the bracket is heated and melted to release the spiral compression spring 42 on its top, pushing the ball ejector pin 61 at the end of the fin to move to a preset angle. When the heat sink 3 is assembled to the bottom of the substrate 1, the corrugated gasket with a ratchet locking ring on the edge is tightened Its compression stroke is driven by a connecting rod mechanism, which fine-tunes the position of the fin ball ejector 61 in the V-shaped guide groove 62, thereby accurately adjusting the fin inclination angle to ensure that it is still tightly against the top of the heat sink 3 when the gap changes at high temperature; when a local hot spot appears on the chip 2, the heat triggers the piezoelectric ceramic vibrator on the top of the package shell 4, driving the gallium indium tin low-melting-point alloy in the closed vortex cavity 8 to produce centrifugal motion, and the droplets are targeted to impact the high-temperature area, significantly enhancing local convective heat transfer. The centrifugal counterweight block suppresses resonance, and the vibration energy is dissipated through the corrugated gasket to protect the contact interface of the lower square matrix. The multi-layer metal sealing ring is combined with the liquid metal filling to ensure the cavity sealing under high-frequency vibration. The entire system realizes efficient, adaptive and self-driven heat dissipation, solving the problems of thermal resistance accumulation, thermal stress cracks and local high temperature.

[0052] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, make some changes or modifications to equivalent embodiments using the technical contents disclosed above. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A semiconductor package structure comprising a substrate, a chip, a heat sink, and a package housing, wherein the chip is disposed on the upper surface of the substrate, the heat sink is disposed below the substrate, the package housing covers the sidewalls of the chip and the upper surface of the substrate, and the bottom of the heat sink is exposed. It also includes an alloy needle matrix arranged below the heat sink and heat-sensitive self-deformable fins arranged between the upper surface of the chip and the packaging shell. The needle bodies of the alloy needle matrix pass through the through holes on the substrate. The needle tips of the alloy needle matrix directly contact the back of the chip through the thermal springs, forming a first heat dissipation path. The heat-sensitive self-deformable fins expand when heated and abut the top of the heat sink, forming a second heat dissipation path. The alloy needle matrix and the heat-sensitive self-deformable fins form a dual-channel vertical heat dissipation system, so that heat is directly transferred from the chip to the heat sink.

2. The semiconductor package structure according to claim 1, wherein: The alloy needle matrix is ​​integrated at the bottom of the radiator. The alloy needles of the alloy needle matrix are tungsten-copper alloy needles. The diameter of the tungsten-copper alloy needles is 0.4mm-0.6mm, and the distance between adjacent tungsten-copper alloy needles is 1.1mm-1.3mm.

3. The semiconductor package structure according to claim 1, wherein: The heat-conducting spring is a beryllium copper spring.

4. The semiconductor package structure according to claim 1, wherein: The heat-induced self-deforming fin is a folded copper-nickel alloy micro-fin. The thickness of the folded copper-nickel alloy micro-fin is 49 μm-51 μm, and the unfolded height is 1.1 mm-1.3 mm.

5. The semiconductor package structure according to claim 1, wherein: A closed vortex cavity is provided on the top of the packaging shell, a low melting point alloy is provided inside the packaging shell at the closed vortex cavity, and a piezoelectric ceramic vibrator is connected to the bottom of the closed vortex cavity.

6. The semiconductor package structure according to claim 5, wherein: The low melting point alloy is a gallium indium tin alloy.

7. A semiconductor packaging method, based on the semiconductor packaging structure according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1: Flip-chip soldering the chip to the upper surface of the substrate to form an electrical connection, install a spring sleeve in the through hole on the substrate, and set a conical buffer head and a cross-shaped elastic claw buckle on the top and bottom of the spring sleeve respectively to absorb the residual stress of welding; S2: Pre-install a tungsten-copper alloy needle matrix on the bottom of the heat sink, allowing the alloy needles to penetrate the preset through-holes in the substrate and contact the back of the chip through beryllium copper springs. A spherical hinge joint is machined at the end of the alloy needle body, so that the spherical hinge joint forms a universal contact with the conical buffer head in S1. Then, a guide rail is set on the edge of the heat sink, and a slider that matches the guide rail is installed on the substrate. The slider is rigidly connected to the tungsten-copper alloy needle matrix through an L-shaped force transmission arm to ensure vertical displacement of the alloy needle body during thermal expansion; S3: Cover the chip with folded copper-nickel alloy micro fins, inject a molded package shell, cover the chip sidewalls and the upper surface of the substrate, and reserve space for the fins to move. Set a fusible space bracket around the fins, set a spiral compression spring on the top of the bracket, and set a tapered positioning pin at the bottom of the bracket. After the package shell is solidified, heat and melt the bracket, release the spiral compression spring, and push the fin to a preset angle. S4: Assemble the radiator under the base plate, seal the needle through-hole, adjust the fin expansion direction toward the top of the radiator to form a dual heat dissipation channel, set ball ejector pins at the end of the fins, and process V-shaped guide grooves on the top of the radiator. The V-shaped guide grooves cooperate with the ball ejector pins at the end of the fins. Install a corrugated gasket between the base plate and the radiator. The gasket edge has a ratchet locking ring. When the locking ring is tightened, the corrugated gasket is compressed to adjust the fin inclination angle through the driving linkage mechanism; S5: A closed vortex cavity is formed on the top of the packaging shell, a low-melting-point alloy is injected into the cavity and a piezoelectric ceramic vibrator is connected. A multi-layer metal sealing ring is set at the bottom of the cavity, and liquid metal is filled between the rings. The piezoelectric ceramic vibrator is crimped to the sealing ring through a butterfly spring group, and a centrifugal counterweight is installed on the top of the cavity.

8. A semiconductor packaging method according to claim 7, characterized in that: The cross-shaped elastic claw buckle of the spring sleeve in step S1 expands radially during thermal expansion, and the expansion amount is converted into vertical displacement compensation through the guide rail.

9. The semiconductor packaging method according to claim 7, wherein: In step S3, the tapered positioning pin of the fusible space bracket is linked to the L-shaped force transmission arm, and after the bracket is melted, the spiral compression spring pushes the ball ejector pin to embed into the V-shaped guide groove.

10. The semiconductor packaging method according to claim 7, wherein: The compression stroke of the corrugated gasket in step S4 drives the ratchet locking ring to rotate through the connecting rod mechanism, and synchronously adjusts the position of the fin ball ejector pin.

Images