Packaging structure and forming method thereof

Abstract

The invention provides a packaging structure and a forming method thereof.The packaging structure comprises a plurality of chips stacked in the direction perpendicular to a lead frame, and at least part of the chips are arranged in a staggered mode in the direction parallel to the lead frame so as to form a suspended area suspended above a base island; the heat conduction column is arranged between the suspension area and the base island. One part of heat generated when the chips work is firstly conducted to the suspended areas of the chips and then rapidly and longitudinally transferred to the base island through the heat conduction columns, the other part of heat is directly transferred to the base island through the chip on the bottommost layer, and finally heat exchange is completed through the base island and an external heat dissipation module. The heat conduction path of the packaging structure is optimized, and the heat dissipation performance of the packaging structure is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of integrated circuit packaging, and more particularly to a packaging structure and a method for forming the same. Background Technology

[0002] With the continuous evolution of microelectronics manufacturing processes and the increasing integration of integrated circuits, modern electronic devices have placed urgent demands on packaging technologies for miniaturization, multifunctionality, low power consumption, and high performance. Multi-chip stacking packaging technology, as a crucial solution to these demands, effectively achieves high integration of chip functions and significant miniaturization of package size by sequentially stacking two or more functional chips in a direction perpendicular to the substrate or carrier. This significantly reduces the packaging footprint while increasing the functional density of system-on-a-chip (SoC), and has become one of the core technological directions in the current advanced packaging field.

[0003] However, this technology faces significant heat dissipation challenges in practical applications: due to the vertical stacking layout of the chips, the vertical spacing between chips is significantly compressed, making it difficult for the heat generated during chip operation to dissipate quickly through traditional horizontal or vertical heat dissipation channels. Simultaneously, the dramatic increase in power density results in heat generation per unit volume far exceeding that of traditional single-chip or planar packaging structures. Furthermore, the heat conduction path is significantly lengthened due to the increased number of stacked layers, and the thermal resistance effects at different material interfaces (such as chip and bonding layer, bonding layer and substrate, chip interconnect bumps and pads) further reduce the efficiency of heat transfer from the heat source to the external environment. This insufficient heat dissipation performance can easily lead to abnormally high temperatures in localized areas, exceeding the temperature tolerance threshold of chip materials (such as silicon substrate, metal interconnects, passivation layers, etc.), thereby causing performance degradation problems such as decreased carrier mobility, increased pn junction leakage current, and dielectric layer breakdown. In severe cases, it can even lead to chip malfunction or permanent damage, greatly limiting the application of multi-chip stacking packaging technology in high-power-density scenarios such as high-performance computing, 5G communication, and artificial intelligence chips.

[0004] Therefore, how to effectively improve the heat dissipation performance of multi-chip stacked packaging structures to meet the heat dissipation requirements under high power density has become one of the key technical problems that urgently need to be solved in the field of microelectronic packaging. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a packaging structure and a method for forming the same, which can effectively improve the heat dissipation performance of multi-chip stacked packaging structures and meet the heat dissipation requirements under high power density.

[0006] To address the aforementioned problems, this invention provides a packaging structure comprising: a lead frame including a base island and pins disposed around the base island; a plurality of chips stacked on the upper surface of the base island along a direction perpendicular to the lead frame, with at least some of the chips offset along a direction parallel to the lead frame, such that a portion of the chips is suspended above the base island; a plurality of heat-conducting pillars vertically disposed on the base island, one end of each pillar disposed on the upper surface of the base island and the other end contacting the suspended area of ​​the chip; a first bonding wire electrically connecting the chips and electrically connecting the chips to the pins; a second bonding wire connected at one end to the pins and extending along a direction perpendicular to the upper surface of the pins; a molding compound covering the lead frame, the chips, the heat-conducting pillars, the first bonding wire, and the second bonding wire, wherein the molding compound does not cover the lower surface of the base island or the other end of the second bonding wire; and a conductive pad disposed on the upper surface of the molding compound and electrically connected to the other end of the second bonding wire.

[0007] In one embodiment, the lead frame further includes a pre-molded body that fills the space between the pin and the base island, and the molded body also covers the surface of the pre-molded body.

[0008] In one embodiment, the lower surface of the pin is covered by the pre-molded body, and when the lead frame includes the pre-molded body, the lower surface of the pin is covered by the pre-molded body.

[0009] In one specific embodiment, the lower surface of the pin is higher than the lower surface of the base island.

[0010] In one specific embodiment, the lower surface of the pin is not covered by the molding compound; when the lead frame includes the pre-molded compound, the lower surface of the pin is not covered by the pre-molded compound.

[0011] In one specific embodiment, the lower surface of the pin is flush with the lower surface of the base island.

[0012] In one specific embodiment, the lower surface of the chip has a thermally conductive adhesive layer, adjacent chips are bonded together through the thermally conductive adhesive layer, and the other end of the thermally conductive pillar is in contact with the thermally conductive adhesive layer.

[0013] In one specific embodiment, all the chips are offset along a direction parallel to the lead frame.

[0014] In one specific embodiment, all or part of the suspended area of ​​the chip is in contact with the heat-conducting pillar.

[0015] In one specific embodiment, the packaging structure includes multiple chipsets, each chipset including one or more chips, the chips within the same chipset being aligned along a direction parallel to the lead frame, the chipsets being staggered along a direction parallel to the lead frame, and the heat-conducting pillars contacting the suspended areas of the chipsets.

[0016] In one specific embodiment, the number of chips in different chipsets may be the same or different.

[0017] In one specific embodiment, the packaging structure includes a first chip stack structure and a second chip stack structure disposed along a direction parallel to the lead frame, wherein the chips in the first chip stack structure and the second chip stack structure are misaligned in opposite directions.

[0018] In one specific embodiment, the packaging structure further includes a top-layer chip, the two edges of the lower surface of which are respectively bonded to the top-layer chip of the first chip stack structure and the top-layer chip of the second chip stack structure via thermally conductive adhesive layers.

[0019] In one specific embodiment, the middle region of the top-layer chip is suspended above the base island and in contact with the heat-conducting pillar.

[0020] In one specific embodiment, the heat-conducting pillars are arranged in a one-to-one correspondence with the chips having suspended areas.

[0021] In one specific embodiment, a plurality of the heat-conducting pillars are arranged corresponding to the same chip having a suspended area.

[0022] In one specific embodiment, the upper surface of the base island has a groove, one end of the heat-conducting pillar is disposed in the groove, and thermally conductive adhesive is filled in the groove to fix the heat-conducting pillar.

[0023] In one specific embodiment, the heat-conducting pillar includes a first connecting portion, a pillar body, and a second connecting portion arranged along a direction perpendicular to the lead frame. The first connecting portion contacts the base island, and the second connecting portion contacts the suspended area of ​​the chip. The cross-sectional area of ​​the first connecting portion is larger than the cross-sectional area of ​​the pillar body.

[0024] In one specific embodiment, the side of the first connecting portion is an inclined surface.

[0025] In one specific embodiment, the surface of the base island has a groove, one end of the heat-conducting pillar is disposed in the groove, and thermally conductive adhesive is filled in the groove to fix the heat-conducting pillar. The inclined surface is partially located in the groove and the other part is located outside the groove, or the entire inclined surface is located in the groove.

[0026] In one specific embodiment, the cross-sectional area of ​​the second connecting portion is larger than the cross-sectional area of ​​the column.

[0027] In one specific embodiment, the side surface of the second connecting portion is an inclined surface.

[0028] In one specific embodiment, the side of the second connecting portion facing the middle region of the chip is an inclined surface, and the side away from the middle region of the chip is a vertical surface.

[0029] In one specific embodiment, the side of the second connecting portion away from the middle region of the chip is flush with the side of the pillar and also flush with the side of the chip.

[0030] In one embodiment, the package includes a plurality of first bonding wires, a portion of which are used to electrically connect the chips to each other, and another portion of which are used to electrically connect the chips to the pins.

[0031] In one specific embodiment, the packaging structure further includes a thermally conductive layer that covers the lower surface of the base island.

[0032] In one specific embodiment, when the lead frame does not include the pre-molded body, the thermally conductive layer also covers all or part of the lower surface of the molded body; when the lead frame includes the pre-molded body, the thermally conductive layer also covers all or part of the lower surface of the pre-molded body.

[0033] This invention also provides a method for forming a package structure, comprising: providing a lead frame, the lead frame including a base island and pins disposed around the base island; disposing of heat-conducting pillars on the upper surface of the base island, the heat-conducting pillars being perpendicularly disposed on the base island; mounting chips on the upper surface of the base island, wherein multiple chips are stacked along a direction perpendicular to the lead frame, and at least some of the chips are offset along a direction parallel to the lead frame, such that a portion of the chips is suspended above the base island, and the end of the heat-conducting pillar away from the base island contacts the suspended portion of the chip; forming a first bonding wire and a second bonding wire. The first bonding wire electrically connects the chips to each other and connects the chips to the pins. One end of the second bonding wire is connected to the pin and extends in a direction perpendicular to the upper surface of the pin. A molding compound is formed, which encapsulates the lead frame, the chips, the thermal pillars, the first bonding wire, and the second bonding wire, but does not cover the lower surface of the base island or the other end of the second bonding wire. A conductive pad is formed on the upper surface of the molding compound, and the conductive pad is electrically connected to the other end of the second bonding wire.

[0034] In one specific embodiment, the step of providing the lead frame further includes: providing a lead frame substrate; etching the lead frame substrate to form the base island and the pin; pre-molding to fill the space between the base island and the pin; and molding to form the molding compound. The step of forming the molding compound further includes: the molding compound also covering the surface of the pre-molded compound.

[0035] In one specific embodiment, during the step of etching the lead frame substrate, the pin is partially etched; during the pre-molding step, the pre-molding body also covers the lower surface of the pin.

[0036] In one specific embodiment, before the step of setting the heat-conducting pillar on the upper surface of the base island, the method includes: forming a groove on the upper surface of the base island; the step of setting the heat-conducting pillar on the upper surface of the base island further includes: placing the heat-conducting pillar in the groove; and filling the groove with thermally conductive adhesive to fix the heat-conducting pillar.

[0037] In one specific embodiment, the heat-conducting pillar includes a first connecting portion, a pillar, and a second connecting portion arranged along a direction perpendicular to the lead frame. The cross-sectional area of ​​the first connecting portion is larger than the cross-sectional area of ​​the pillar and / or the cross-sectional area of ​​the second connecting portion is larger than the cross-sectional area of ​​the pillar. The step of setting the heat-conducting pillar on the upper surface of the base island further includes: contacting the first connecting portion with the base island; the step of mounting the chip on the upper surface of the base island further includes: contacting the second connecting portion with the suspended area of ​​the chip.

[0038] In one specific embodiment, the side of the first connecting part is an inclined surface, and the step of setting the heat-conducting pillar on the upper surface of the base island further includes: placing all or part of the inclined surface of the first connecting part in the groove on the upper surface of the base island.

[0039] In one specific embodiment, the side of the second connecting portion facing the middle region of the chip is an inclined surface, and the side away from the middle region of the chip is a vertical surface; the step of mounting the chip on the surface of the base island further includes, when mounting the chip, making the side of the chip flush with the side plate of the second connecting portion of the heat-conducting pillar.

[0040] In one specific embodiment, the step of mounting chips on the upper surface of the base island further includes: forming a thermally conductive adhesive layer on the lower surface of the chip, bonding adjacent chips together through the thermally conductive adhesive layer, and having one end of the thermally conductive pillar away from the base island in contact with the thermally conductive adhesive layer.

[0041] In one specific embodiment, the step of mounting chips on the surface of the base island further includes: sequentially staggering the chips along a direction parallel to the lead frame, with all or part of the suspended areas of the chips in contact with the heat-conducting pillars.

[0042] In one specific embodiment, the step of mounting chips on the surface of the base island further includes: forming multiple chip groups on the surface of the base island, each chip group including one or more chips, the number of chips in different chip groups being the same or different, the chips in the same chip group being aligned along a direction parallel to the lead frame, the chip groups being staggered along a direction parallel to the lead frame, and the heat-conducting pillars contacting the suspended area of ​​the chip groups.

[0043] In one specific embodiment, the step of mounting chips on the upper surface of the base island further includes: forming a first chip stack structure and a second chip stack structure on the upper surface of the base island, which are arranged in a direction parallel to the lead frame, wherein the chips in the first chip stack structure and the second chip stack structure are arranged in opposite directions.

[0044] In one specific embodiment, after the step of forming a first chip stack structure and a second chip stack structure arranged parallel to the lead frame direction on the upper surface of the base island, the method further includes: forming a top chip on the first chip stack structure and the second chip stack structure, wherein the two edges of the lower surface of the top chip are respectively bonded to the topmost chip of the first chip stack structure and the topmost chip of the second chip stack structure through a thermally conductive adhesive layer, and the middle region of the top chip is suspended above the base island and in contact with the thermally conductive pillar.

[0045] In one specific embodiment, the step of mounting chips on the surface of the base island further includes: arranging the chips such that the chips with suspended areas are arranged in a one-to-one correspondence with the heat-conducting pillars.

[0046] In one specific embodiment, the step of mounting the chip on the surface of the base island further includes: arranging the chip so that the chip with the same suspended area is correspondingly arranged with a plurality of the heat-conducting pillars.

[0047] In one specific embodiment, the steps of forming the first bonding wire and the second bonding wire further include: performing a first wire bonding process to form the first bonding wire; and performing a vertical wire bonding process to form the second bonding wire.

[0048] In one specific embodiment, the step of forming a conductive connection pad on the upper surface of the molding compound or after the step of forming a conductive connection pad on the upper surface of the molding compound further includes: forming a thermally conductive layer, the thermally conductive layer at least covering the lower surface of the base island.

[0049] The packaging structure and its formation method provided in the specific embodiments of the present invention include a plurality of chips stacked along a direction perpendicular to the lead frame, with at least some of the chips offset along a direction parallel to the lead frame to form a suspended region above the base island. A heat-conducting pillar is disposed between the suspended region and the base island, constructing a cascaded heat dissipation channel of "suspended region - heat-conducting pillar - base island". When the chips are operating, a portion of the heat generated is first conducted to the suspended region of the chips. This suspended region, free from thermal interference from adjacent chips, forms a localized low-temperature zone. Heat is rapidly transferred longitudinally to the base island here via the heat-conducting pillar. Another portion of the heat is directly transferred to the base island through the bottommost chip, and finally, the base island exchanges heat with an external heat dissipation module (such as heat sink fins, liquid cooling pipes, or heat pipe systems). The present invention optimizes the heat conduction path of the packaging structure, greatly improving its heat dissipation performance. Furthermore, the heat-conducting pillars can also support the suspended area of ​​the chip, thereby reducing the overlapping area between adjacent chips, increasing the area of ​​the suspended area, and further increasing the heat dissipation performance of the packaging structure. In addition, the supporting effect of the heat-conducting pillars can further prevent the chip from tilting and improve the reliability of the packaging structure.

[0050] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit the invention. Techniques, methods, and apparatus known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and apparatus should be considered part of the specification. Attached Figure Description

[0051] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0052] Figure 1 This is a schematic diagram of the packaging structure provided in the first specific embodiment of the present invention; Figure 2 This is a schematic diagram of the packaging structure provided in the second specific embodiment of the present invention; Figure 3 This is a schematic diagram of the packaging structure provided in the third specific embodiment of the present invention; Figure 4 This is a schematic diagram of the packaging structure provided in the fourth specific embodiment of the present invention. Figure 5 This is a schematic diagram of the packaging structure provided in the fifth specific embodiment of the present invention; Figure 6 This is a schematic diagram of the packaging structure provided in the sixth specific embodiment of the present invention; Figure 7 This is a schematic diagram of the packaging structure provided in the seventh specific embodiment of the present invention; Figure 8 This is a schematic diagram of the packaging structure provided in the eighth specific embodiment of the present invention; Figure 9 This is a schematic diagram of the packaging structure provided in the ninth specific embodiment of the present invention; Figure 10 This is a schematic diagram of the chip and heat-conducting pillar distribution in the packaging structure provided in the first specific embodiment of the present invention; Figure 11 This is an enlarged schematic diagram of region A in the packaging structure provided in the first specific embodiment of the present invention; Figure 12 This is a schematic diagram of the steps of the method for forming the packaging structure provided in the first specific embodiment of the present invention; Figure 13 This is a schematic diagram of the lead frame substrate in the method for forming the packaging structure provided in the first specific embodiment of the present invention; Figure 14 This is a schematic diagram of the lead frame in the method for forming the packaging structure provided in the first specific embodiment of the present invention; Figure 15 This is a schematic diagram of the pre-molding of the lead frame in the method for forming the packaging structure provided in the first specific embodiment of the present invention; Figure 16 This is a schematic diagram of the method for forming the packaging structure provided in the first specific embodiment of the present invention, in which heat-conducting pillars are set; Figure 17 This is a schematic diagram of chip mounting in the method for forming a packaging structure provided in the first specific embodiment of the present invention; Figure 18 This is a schematic diagram of the formation of the first bonding wire in the method for forming the packaging structure provided in the first specific embodiment of the present invention; Figure 19 This is a schematic diagram of the formation of the second bonding wire in the method for forming the packaging structure provided in the first specific embodiment of the present invention; Figure 20 This is a schematic diagram of the formation of a plastic encapsulation body in the method for forming an encapsulation structure provided in the first specific embodiment of the present invention.

[0053] Explanation of reference numerals in the attached figures: 100 lead frame 101 Base Island 102 pins 103 grooves 104 thermal conductive adhesive 110 chip 111 Suspended Area 112 overlapping regions 113 thermally conductive adhesive layer 120 thermal column 121 First Connecting Part 122 column 123 Second connecting part 130 First Welding Line 140 Second Welding Line 150 molded body 160 conductive pad 170 pre-molded sealant 180 First Chip Stacking Structure 181 Second Chip Stacking Structure 182 top-level chip 190 thermal conductive layer 300 lead frame substrate 400 chipset. Detailed Implementation

[0054] The technical solutions in the embodiments of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. 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.

[0055] Figure 1 This is a schematic diagram of the packaging structure provided in the first specific embodiment of the present invention. Please refer to [the diagram]. Figure 1The package structure includes: a lead frame 100, including a base island 101 and pins 102 disposed around the base island 101; a plurality of chips 110, stacked on the upper surface of the base island 101 along a direction perpendicular to the lead frame 100 (Z direction in the figure), at least some of the chips 110 being offset along a direction parallel to the lead frame 100 (X direction in the figure), such that a portion of the chips 110 is suspended above the base island 101; and a plurality of heat-conducting pillars 120, the heat-conducting pillars 120 being vertically disposed on the base island 101, one end of the heat-conducting pillar 120 being disposed on the upper surface of the base island 101, and the other end being suspended from the chips 110. Region 111 is contacted; a first bonding wire 130 electrically connects the chips 110 to each other and connects the chips 110 to the pin 102; a second bonding wire 140 is connected at one end to the pin 102 and extends in a direction perpendicular to the upper surface of the pin 102; a molding compound 150 covers the lead frame 100, the chips 110, the heat-conducting pillars 120, the first bonding wire 130 and the second bonding wire 140, and the molding compound 150 does not cover the lower surface of the base island 101 and the other end of the second bonding wire 140; a conductive pad 160 is disposed on the upper surface of the molding compound 150 and electrically connected to the other end of the second bonding wire 140.

[0056] The packaging structure provided in the specific embodiment of the present invention includes a plurality of chips 110 stacked along a direction perpendicular to the lead frame 100. At least some of the chips 110 are offset along a direction parallel to the lead frame 100 to form a suspended region 111 suspended above the base island 101. A heat-conducting pillar 120 is disposed between the suspended region 111 and the base island 101, thereby constructing a cascaded heat dissipation channel of "suspended region 111-heat-conducting pillar 120-base island 101". When the chip 110 operates, a portion of the heat generated is first conducted to the suspended region 111 of the chip 110. This suspended region 111, free from thermal interference from adjacent chips 110, forms a localized low-temperature zone. Heat is rapidly transferred longitudinally from this zone to the base island 101 via the heat-conducting pillar 120. Another portion of the heat is directly transferred to the base island 101 through the bottommost chip 110. Finally, the base island 101 exchanges heat with an external heat dissipation module (such as heat sink fins, liquid cooling pipes, or a heat pipe system). This invention optimizes the heat conduction path of the packaging structure, significantly improving its heat dissipation performance. Furthermore, the heat-conducting pillar 120 supports the suspended region 111 of the chip 110, thereby reducing the overlap between adjacent chips 110, increasing the area of ​​the suspended region 111, and further enhancing the heat dissipation performance of the packaging structure. The supporting effect of the heat-conducting pillar 120 also prevents the chip 110 from tilting, improving the reliability of the packaging structure.

[0057] The lead frame 100 includes a base island 101 and pins 102 disposed around the base island 101. The base island 101 supports the chip 110 and provides stable mechanical support. The base island 101 includes an upper surface and a lower surface disposed opposite each other. The chip 110 is disposed on the upper surface of the base island 101, and the lower surface of the base island 101 can serve as a heat dissipation surface of the package structure for heat exchange with an external heat dissipation module. The pins 102 are distributed circumferentially along the base island 101 at equal or gradient intervals. The chip 110 is electrically connected to the pins 102 via bonding wires, and the pins 102 are electrically connected to external devices, thereby realizing the electrical lead-out of the chip 110. In this specific embodiment, the chip 110 is electrically connected to the pin 102 via the first bonding wire 130, and the pin 102 is electrically connected to the conductive connection pad 160 located on the surface of the molding compound 150 via the second bonding wire 140. The conductive connection pad 160 serves as the electrical connection interface between the package structure and external devices, forming a reliable mechanical connection and electrical conduction with external devices (such as PCB boards and connectors), thereby constructing a complete electrical signal transmission path from the internal circuit of the chip 110 to the external system.

[0058] In this specific embodiment, the lower surface of the pin 102 is covered by a pre-molded enclosure 170. Specifically, the lower surface of the pre-molded enclosure 170 is flush with the lower surface of the base island 101, and the lower surface of the pin 102 is higher than the lower surface of the base island 101, ensuring that the pin 102 is completely located within the pre-molded enclosure 170, avoiding the risk of short circuits caused by direct contact with external devices. In other specific embodiments, the package structure does not include the pre-molded enclosure 170, and the lower surface of the pin 102 is covered by a molding compound 150. Specifically, the pin 102 includes an upper surface and a lower surface disposed opposite to each other. The upper surface of the pin 102 serves as a wire bonding area, and the first wire 130 and the second wire 140 are connected to the upper surface of the pin 102. The lower surface of the pin 102 is located within the molding compound 150, and the molding compound 150 protects the lower surface of the pin 102 to achieve mechanical protection and electrical isolation.

[0059] In another specific embodiment, the lower surface of the pin 102 is not covered by the pre-molded body 170 and the molded body 150. Furthermore, the lower surface of the pin 102 is flush with the lower surface of the base island 101. Specifically, as... Figure 2The diagram illustrates a packaging structure provided in a second embodiment of the present invention. In this embodiment, the lower surface of the pin 102 is exposed to the pre-molded enclosure 170, and the lower surface of the pin 102 is flush with the lower surface of the base island 101. The lower surface of the pin 102 can serve as another electrical connection interface for the packaging structure to connect with other packaging structures, enabling the stacking of multiple packaging structures. In other embodiments, the lower surface of the pin 102 can also serve as a heat dissipation surface of the packaging structure to exchange heat with an external heat dissipation module, improving the heat dissipation performance of the packaging structure. Furthermore, when forming the packaging structure, it is not necessary to etch the area of ​​the pin 102 to make its lower surface higher than the lower surface of the base island 101, simplifying the fabrication process of the packaging structure.

[0060] The chip 110 is disposed on the base island 101 and may include a logic processing chip, a memory cell chip, a sensor chip, a control chip, a radio frequency chip, etc. Multiple chips 110 are stacked on the upper surface of the base island 101 along a direction perpendicular to the lead frame 100 to form a chip stack structure. Each chip 110 includes an upper surface and a lower surface opposite to each other. The upper surface is the active surface of the chip 110, and the lower surface is the back surface of the chip 110. In the chip stack structure, each chip 110 is arranged with its active surface facing upwards and its back surface facing downwards. Specifically, the back surface of the bottom layer of chips 110 is disposed on the upper surface of the base island 101, and its active surface faces away from the base island 101. The back surface of the second layer of chips 110 is disposed on the active surface of the bottom layer of chips 110, and its active surface faces away from the bottom layer of chips 110. Other chips 110 are arranged in this manner to form a chip stack structure on the upper surface of the base island 101. In the chip stacking structure, the area on the active surface of the chip 110 that needs to be electrically connected to the first bonding wire 130 is not covered by the chip 110 above it, so as to be used for electrical connection with the first bonding wire 130.

[0061] In one specific embodiment, the lower surface of the chip 110 has a thermally conductive adhesive layer 113, and adjacent chips 110 are bonded together through the thermally conductive adhesive layer 113. The bottommost chip 110 is fixed to the base island 101 through the thermally conductive adhesive layer 113. The thermally conductive adhesive layer 113 has high thermal conductivity and adhesion to achieve excellent thermal conductivity and fixation.

[0062] In some specific embodiments, the thermally conductive adhesive layer 113 uses a polymer matrix and a highly thermally conductive filler as a reinforcing phase, with its overall performance enhanced through nano-reinforcement or interface modification. The thermally conductive adhesive layer 113 can be an epoxy resin-based thermally conductive adhesive, a silicone-based thermally conductive adhesive, a sintered silver paste, etc. The epoxy resin-based thermally conductive adhesive uses epoxy resin as the matrix and ceramic fillers such as boron nitride (BN), alumina (Al2O3), and aluminum nitride (AlN) as reinforcing phases. Epoxy resin has excellent adhesive strength, chemical corrosion resistance, and electrical insulation. The three-dimensional network structure formed after curing can effectively fix the position of the chip 110, preventing chip displacement during stacking. The ceramic fillers such as boron nitride (BN), alumina (Al2O3), and aluminum nitride (AlN) have high thermal conductivity, suitable for the insulation and heat dissipation requirements in chip 110 stacking. Silicone-based thermally conductive adhesives use silicone as the matrix and nanofillers such as graphene (GN) and silicon carbide (SiC) as reinforcing phases. Silicone possesses excellent flexibility, wide temperature range adaptability, and low stress characteristics, making it suitable for flexible connections or heterogeneous chips with large differences in thermal expansion in chip stacking. Nanofillers such as graphene (GN) and silicon carbide (SiC) can significantly improve thermal conductivity. Sintered silver paste uses nano-silver particles as fillers and forms metal-metal bonds through a sintering process. It has ultra-high thermal conductivity and high electrical conductivity, making it an excellent material for high-power chip stacking.

[0063] In the chip stacking structure, at least some of the chips 110 are staggered along a direction parallel to the lead frame 100 (as shown by the X direction in the figure), forming a stepped layout. Part of these chips 110 are suspended above the base island 101 as suspended regions 111, and part of these regions overlap with the adjacent chips 110 below them as overlapping regions 112. The suspended regions 111 of the chips 110 form local low-temperature zones due to their isolation from the thermal interference of adjacent chips 110. Heat is rapidly transferred longitudinally to the base island 101 here through the heat-conducting pillars 120 in contact with them.

[0064] The heat-conducting pillar 120 is vertically disposed on the base island 101, with one end disposed on the upper surface of the base island 101 and the other end in contact with the suspended area 111 of the chip 110. That is, in the direction perpendicular to the lead frame 100, the heat-conducting pillar 120 is disposed between the suspended area 111 of the chip 110 and the base island 101, serving as an intermediate structure for heat conduction. The heat generated by the chip 110 can be rapidly and longitudinally transferred to the base island 101 through the heat-conducting pillar 120, and finally, the base island 101 completes heat exchange with an external heat dissipation module (e.g., heat sink fins, liquid cooling pipes, or heat pipe systems). This invention optimizes the heat conduction path of the packaging structure, greatly improving the heat dissipation performance of the packaging structure. In some specific embodiments, in the suspended area 111 of the chip 110, the heat-conducting pillar 120 contacts the thermally conductive adhesive layer 113 on the lower surface of the chip 110, and the thermally conductive adhesive layer 113 can further fix the heat-conducting pillar 120.

[0065] The first bonding wire 130 electrically connects the chips 110 to each other and electrically connects the chips 110 to the pins 102. In one embodiment, the package structure includes a plurality of the first bonding wires 130, a portion of which is used to electrically connect the chips 110 to each other, and another portion of which is used to electrically connect the chips 110 to the pins 102. As an example, such as Figure 1 As shown, in the first specific embodiment, the area of ​​the topmost chip 110 that needs to be connected externally is electrically connected to the chip 110 below it through the first bonding wire 130. The chip 110 below it is then electrically connected to another chip 110 below it through the first bonding wire 130. Multiple chips 110 are connected sequentially. The bottommost chip 110 is connected to the pin 102 through the first bonding wire 130, thereby realizing the electrical connection between multiple chips 110 and the pin 102. Multiple pins 102 can be arranged around the base island 101. The pads with different active surfaces of the chip 110 can be connected to different pins 102 through the first bonding wire 130. The first bonding wire 130, as the interconnection structure connecting the chip 110 and the pin 102 in the package structure, needs to consider multiple dimensions of requirements such as conductivity, reliability, process compatibility, and cost when selecting its material. The materials of the first bonding wire 130 include gold wire, copper wire, and alloy wire.

[0066] One end of the second bonding wire 140 is connected to the pin 102 and extends in a direction perpendicular to the upper surface of the pin 102, such as... Figure 1The second bonding wire 140 extends along the Z-direction to the upper surface of the molding compound 150. The second bonding wire 140 is a vertical bonding wire, used to electrically lead the pin 102 to the conductive pad 160. The vertical extension of the second bonding wire 140 avoids the space occupied by traditional horizontal bonding wires, increasing the packaging density of the package structure. Furthermore, the second bonding wire 140 forms a vertical heat dissipation channel, allowing heat generated by the package structure to be conducted to the conductive pad 160 and then dissipated through the conductive pad 160, improving the heat dissipation efficiency of the package structure. The material of the second bonding wire 140 includes gold wire, copper wire, and alloy wire, and it can be the same material as the first bonding wire 130.

[0067] The molding compound 150 encapsulates the lead frame 100, the chip 110, the heat-conducting pillar 120, the first bonding wire 130, and the second bonding wire 140, but does not cover the lower surface of the base island 101 or the other end of the second bonding wire 140. The molding compound 150 is made of thermosetting materials such as epoxy resin, which uniformly covers the entire upper surface of the lead frame 100, forming a reliable physical protective layer. The molding compound 150 has good mechanical strength, thermal stability, and moisture resistance, effectively protecting the internal structure from the influence of the external environment (such as moisture, dust, mechanical stress, etc.), while providing structural support for subsequent cutting, testing, and assembly processes. Furthermore, the thickness and shape of the molding compound 150 can be precisely controlled according to the packaging type to meet the requirements of different application scenarios for packaging size and heat dissipation performance.

[0068] In this specific embodiment, the lead frame 100 is a pre-molded lead frame 100, and the space between the base island 101 and the pin 102 is filled by a pre-molded body 170, which also covers the upper surface of the pre-molded body 170. Furthermore, in this specific embodiment, the lower surface of the pin 102 is covered by the pre-molded body 170. Further, the pre-molded body 170 and the molded body 150 are made of the same material, for example, both are epoxy resin, to provide a strong bond between them.

[0069] The lower surface of the base island 101 is not covered by the molding compound 150 and the pre-molding compound 170, and can serve as a heat dissipation surface of the package structure. In the second embodiment, the lower surface of the pin 102 is also not covered by the molding compound 150 and the pre-molding compound 170, so that it can serve as another electrical connection interface for external connection of the package structure and a heat dissipation surface of the package structure.

[0070] The conductive pad 160 is disposed on the upper surface of the molding compound 150 and electrically connected to the other end of the second bonding wire 140. The conductive pad 160 serves as the electrical connection interface of the encapsulation structure for electrical connection with external devices, achieving low impedance conduction through copper-based or nickel-gold plated materials. In this specific embodiment, the conductive pad 160 protrudes from the upper surface of the molding compound 150. In other specific embodiments, a portion of the conductive pad 160 may be located within the molding compound 150, while a portion may protrude from the upper surface of the molding compound 150.

[0071] The packaging structure provided by the specific embodiments of the present invention effectively achieves high integration of chip 110 functions and significant miniaturization of package size through the stacking arrangement of chip 110. However, the stacking arrangement significantly increases the heat conduction path, which is not conducive to heat dissipation of the packaging structure. The present invention further optimizes the heat conduction path by staggering at least part of the chip 110 along the direction parallel to the lead frame 100 to form a suspended region 111, and connects the suspended region 111 of the chip 110 to the base island 101 through the heat-conducting pillar 120, thereby achieving rapid longitudinal heat conduction, effectively improving the heat dissipation performance of the stacked structure, and meeting the heat dissipation requirements of the packaging structure.

[0072] In the packaging structure, multiple chips 110 have various stacking methods to meet different packaging requirements.

[0073] As an example, such as Figure 3 The diagram illustrates a packaging structure provided in a third embodiment of the present invention. In this third embodiment, multiple chips 110 form a chip stack structure. All chips 110 are staggered along a direction parallel to the lead frame 100. The chips 110 are connected by a thermally conductive adhesive layer 113. Except for the bottommost chip 110, each chip 110 has a suspended region 111, which contacts one or more thermally conductive pillars 120 to improve the heat dissipation performance of the packaging structure. Furthermore, in this embodiment, all chips 110 have the same size.

[0074] As an example, such as Figure 4The diagram illustrates a packaging structure provided in the fourth embodiment of the present invention. In this fourth embodiment, the packaging structure includes multiple chip groups 400, each chip group 400 including one or more chips 110. Chips 110 within the same chip group 400 are aligned along a direction parallel to the lead frame 100. Chip groups 400 are also staggered along a direction parallel to the lead frame 100. A heat-conducting pillar 120 contacts the suspended area 111 of the chip group 400, specifically, the heat-conducting pillar 120 contacts the suspended area 111 of the bottommost chip 110 in the chip group 400, thereby achieving heat conduction of the chip group 400. In this embodiment, some chips 110 in the chip stack structure are not staggered, while others are staggered, which can meet different packaging requirements. Furthermore, the number of chips 110 in different chip groups 400 may be the same or different. In the fourth embodiment, taking the example that the number of chips 110 in different chipsets 400 is the same, each chipset 400 includes two chips 110. The chip 110 located at the bottom layer can be electrically connected to the chip 110 located at the top layer through conductive structures such as through-silicon vias. The chip 110 located at the top layer can be electrically connected to the chips 110 of other chipsets 400 through the first bonding wire 130. In other embodiments, the number of chips 110 in different chipsets 400 is not the same. For example, some chipsets 400 contain one chip 110, some chipsets 400 contain two chips 110, and still others contain three chips 110.

[0075] In the third and fourth embodiments, multiple chips 110 are stacked to form a chip stack structure. In other embodiments, the multiple chips 110 can be divided into multiple groups of chip stack structures, which are arranged in parallel in a direction parallel to the lead frame 100 to accommodate both the longitudinal and lateral dimensions of the package structure. Furthermore, the chips 110 in different groups of chip stack structures are arranged in opposite or the same directions. In some embodiments, different chip stack structures may contain the same or different numbers of chips 110.

[0076] As an example, such as Figure 1As shown, in a first embodiment, the packaging structure includes a first chip stack structure 180 and a second chip stack structure 181 disposed along a direction parallel to the lead frame 100. The chips 110 in the first chip stack structure 180 and the second chip stack structure 181 are staggered in opposite directions. Specifically, the first chip stack structure 180 includes a plurality of chips 110 staggered to the right, and the second chip stack structure 181 includes a plurality of chips 110 staggered to the left. The first chip stack structure 180 and the second chip stack structure 181 contain the same number of chips. In other embodiments, the first chip stack structure 180 and the second chip stack structure 181 contain different numbers of chips. Both the first chip stack structure 180 and the second chip stack structure 181 can transfer heat to the base island 101 through heat-conducting pillars 120 that contact the suspended area 111 of their chips 110. This ensures that the heat conduction paths of the first chip stack structure 180 and the second chip stack structure 181 are independent and do not interfere with each other, thereby eliminating the thermal coupling effect between the chip stack structures, ensuring the heat diffusion efficiency of each chip stack structure, and further improving the heat dissipation performance of the package structure. In another specific embodiment, multiple sets of first chip stack structures 180 and second chip stack structures 181 can be arranged along the direction parallel to the lead frame 100.

[0077] As an example, such as Figure 5 The diagram shown is a schematic of a packaging structure provided in a fifth embodiment of the present invention. In this fifth embodiment, the packaging structure includes a first chip stack structure 180 and a second chip stack structure 181 disposed along a direction parallel to the lead frame 100. The chips 110 in the first chip stack structure 180 and the second chip stack structure 181 are staggered in the same direction. Specifically, the first chip stack structure 180 and the second chip stack structure 181 include a plurality of chips 110 disposed sequentially to the right, and the number of chips 110 contained in the first chip stack structure 180 and the second chip stack structure 181 is the same. In other embodiments, the number of chips 110 contained in the first chip stack structure 180 and the second chip stack structure 181 is different.

[0078] In some specific embodiments, the packaging structure includes multiple sets of chip stacked structures, and a top-layer chip can be disposed on two adjacent sets of chip stacked structures to further increase the number of chips in the packaging structure and improve the integration of the packaging structure. As an example, such as... Figure 1As shown, in the first specific embodiment, the packaging structure further includes a top-layer chip 182. The two edges of the lower surface of the top-layer chip 182 are respectively bonded to the uppermost chip 110 of the first chip stack structure 180 and the uppermost chip 110 of the second chip stack structure 181 via a thermally conductive adhesive layer 113. Furthermore, the middle region of the top-layer chip 182 is suspended above the base island 101 and in contact with the thermally conductive pillar 120. The heat generated by the top-layer chip 182 is conducted to the base island 101 through the thermally conductive pillar 120.

[0079] The above specific embodiments are merely examples of the chip 110 arrangement in the packaging structure. In other specific embodiments, an appropriate chip 110 arrangement can be selected according to the requirements of the packaging structure.

[0080] In the encapsulation structure, the heat-conducting pillars 120 are an important part of the heat conduction path, and their arrangement is also diverse.

[0081] In some specific embodiments, the heat-conducting pillars 120 are configured in a one-to-one correspondence with the chips 110 having suspended regions 111. As an example, such as... Figure 1 As shown, in the first specific embodiment, all chips 110 of the first chip stack structure 180 are staggered along a direction parallel to the lead frame 100, and each chip 110 with a suspended region 111 is correspondingly arranged with a heat-conducting pillar 120. Figure 4 As shown, in the fourth specific embodiment, the packaging structure includes a plurality of chip groups 400, which are staggered along the direction parallel to the lead frame 100, and each chip group 400 with a suspended area is correspondingly provided with a heat-conducting pillar 120.

[0082] In some specific embodiments, multiple heat-conducting pillars 120 are correspondingly arranged with respect to the same chip 110 having a suspended region 111. As an example, such as... Figure 10The diagram shown is a bottom view and illustrates the distribution of chip 110 and heat-conducting pillars 120 in the packaging structure provided by the first embodiment of the present invention. The chip 110 includes a suspended region 111 and an overlapping region 112 stacked with adjacent chips 110. The suspended region 111 and the overlapping region 112 are arranged parallel to the lead frame 100. Multiple heat-conducting pillars 120 are spaced apart and contact the suspended region 111 of the chip 110 in a direction perpendicular to the arrangement of the suspended region 111 and the overlapping region 112 (as shown by the Y direction in the diagram). The multiple heat-conducting pillars 120 increase the heat conduction path of the chip 110, allowing the heat generated by the chip 110 to be quickly and longitudinally transferred to the base island 101 through the heat-conducting pillars 120, greatly improving the heat dissipation performance of the packaging structure. In other specific embodiments, multiple spaced heat-conducting pillars 120 may be provided in the direction of the arrangement of the suspended region 111 and the overlapping region 112 (as shown by the X direction in the figure) to further improve the heat dissipation performance of the packaging structure.

[0083] In some specific embodiments, to increase the stability of the heat-conducting pillar 120 and further increase the heat conduction area between the heat-conducting pillar 120 and the base island 101, the upper surface of the base island 101 has a groove 103, one end of the heat-conducting pillar 120 is disposed in the groove 103, and thermally conductive adhesive 104 is filled in the groove 103 to fix the heat-conducting pillar 120. Specifically, as... Figure 11 As shown, this is an enlarged schematic diagram of region A in the packaging structure provided in the first embodiment of the present invention. In the first embodiment, the upper surface of the base island 101 has a groove 103 extending toward the interior of the base island 101. One end of the heat-conducting pillar 120 is disposed in the groove 103, and the bottom surface of the heat-conducting pillar 120 contacts the bottom surface of the groove 103. Thermally conductive adhesive 104 fills the groove 103 and covers the side surface of the heat-conducting pillar 120 to fix the heat-conducting pillar 120. A portion of the heat from the heat-conducting pillar 120 is transferred to the base island 101 through its bottom surface in contact with the groove 103, and another portion of the heat is transferred to the base island 101 through the thermally conductive adhesive 104, thereby improving the heat conduction efficiency of the heat-conducting pillar 120 while ensuring its stability.

[0084] In some specific embodiments, the heat conduction area between the heat-conducting pillar 120 and the base island 101 is further increased by increasing the area of ​​the connection region between the heat-conducting pillar 120 and the base island 101. As an example, such as Figure 6The diagram shown is an enlarged schematic of region A of the packaging structure provided in the sixth embodiment of the present invention. In the sixth embodiment, the heat-conducting pillar 120 includes a first connecting portion 121, a pillar 122, and a second connecting portion 123 arranged along a direction perpendicular to the lead frame 100. The first connecting portion 121 contacts the base island 101, and the second connecting portion 123 contacts the suspended region 111 of the chip 110. The cross-sectional area of ​​the first connecting portion 121 is larger than the cross-sectional area of ​​the pillar 122. Specifically, in this embodiment, the first connecting portion 121 is cylindrical, and its diameter is larger than that of the pillar 122, which increases the bottom area of ​​the heat-conducting pillar 120 and the side area of ​​the first connecting portion 121, thereby increasing the contact area between the heat-conducting pillar 120 and the base island 101, as well as the contact area between the thermally conductive adhesive 104 and the heat-conducting pillar 120, thus increasing the thermal conductivity area between the heat-conducting pillar 120 and the base island 101 and improving the thermal conductivity efficiency of the packaging structure. In this specific embodiment, the cross-sectional area of ​​the first connecting portion 121 of all the heat-conducting pillars 120 in the encapsulation structure is larger than the cross-sectional area of ​​the pillar 122. In other specific embodiments, only some of the heat-conducting pillars 120 may have a cross-sectional area of ​​the first connecting portion 121 that is larger than the cross-sectional area of ​​the pillar 122, in order to adapt to the needs of different encapsulation structures.

[0085] As an example, such as Figure 7 The diagram shows a schematic of region A of the encapsulation structure provided in the seventh embodiment of the present invention. In the seventh embodiment, the side of the first connecting portion 121 is an inclined surface, and the cross-section of the first connecting portion 121 is trapezoidal. The thermally conductive adhesive 104 can climb along the inclined surface, further increasing the contact area between the thermally conductive adhesive 104 and the thermally conductive pillar 120, thereby increasing the heat conduction area between the thermally conductive pillar 120 and the base island 101, and improving the thermal conductivity of the encapsulation structure. Further, in this embodiment, all the inclined surfaces are located within the groove 103. In another embodiment, part of the inclined surface is located within the groove 103, and another part is located outside the groove 103. In this embodiment, the side of the first connecting portion 121 of all the thermally conductive pillars 120 in the encapsulation structure is an inclined surface. In other embodiments, only the side of the first connecting portion 121 of some of the thermally conductive pillars 120 may be an inclined surface to adapt to the needs of different encapsulation structures.

[0086] In some specific embodiments, the heat conduction area between the heat-conducting pillar 120 and the chip 110 is further increased by increasing the area of ​​the connection region between the heat-conducting pillar 120 and the chip 110.

[0087] As an example, such as Figure 6 As shown, in the sixth embodiment, the cross-sectional area of ​​the second connecting portion 123 is larger than the cross-sectional area of ​​the column 122. Specifically, in this embodiment, the second connecting portion 123 is cylindrical, with a diameter larger than that of the column 122. This increases the top surface area of ​​the heat-conducting column 120 and the side surface area of ​​the second connecting portion 123, thereby increasing the contact area between the heat-conducting column 120 and the suspended area 111 of the chip 110, as well as the contact area between the thermally conductive adhesive layer 113 on the surface of the chip 110 and the heat-conducting column 120. This increases the heat conduction area between the heat-conducting column 120 and the chip 110, improving the thermal conductivity of the packaging structure. In this embodiment, the cross-sectional area of ​​the second connecting portion 123 of all the heat-conducting columns 120 in the packaging structure is larger than that of the column 122. In other embodiments, only some of the heat-conducting columns 120 may have a cross-sectional area of ​​the second connecting portion 123 larger than that of the column 122 to accommodate the needs of different packaging structures.

[0088] As an example, such as Figure 7 As shown, in the seventh embodiment, the side of the second connecting portion 123 is an inclined surface, and the cross-section of the second connecting portion 123 is trapezoidal. The thermally conductive adhesive 104 can climb along the inclined surface, further increasing the contact area between the thermally conductive adhesive layer 113 and the thermally conductive pillar 120, thereby increasing the thermal conduction area between the thermally conductive pillar 120 and the chip 110 and improving the thermal conductivity of the packaging structure. The inclined side of the second connecting portion 123 also allows the thermally conductive adhesive layer 113 on the lower surface of the chip 110 to preferentially climb along the inclined surface, preventing the thermally conductive adhesive 104 from spreading to other areas of the chip 110 and contaminating it. In this embodiment, the side of the second connecting portion 123 of all the thermally conductive pillars 120 in the packaging structure is an inclined surface. In other embodiments, only the side of the second connecting portion 123 of some of the thermally conductive pillars 120 may be an inclined surface to adapt to the needs of different packaging structures.

[0089] In a seventh embodiment, all surfaces of the second connecting portion 123 of the heat-conducting pillar 120 are inclined surfaces; in another embodiment, a portion of the surface of the second connecting portion 123 of the heat-conducting pillar 120 is an inclined surface. As an example, such as... Figure 8The diagram shown is a schematic diagram of region A of the packaging structure provided in the eighth embodiment of the present invention. In this embodiment, if the suspended region 111 of the chip 110 is small, the side of the second connecting portion 123 facing the middle region of the chip 110 is an inclined surface, and the side away from the middle region of the chip 110 is a vertical surface, so as to maximize the heat conduction area between the heat-conducting pillar 120 and the chip 110 within a limited space. Furthermore, the side of the second connecting portion 123 away from the middle region of the chip 110 is flush with the side of the pillar 122 and with the side of the chip 110. In this packaging structure, the shape of the second connecting portion 123 of the heat-conducting pillar 120 is set according to parameters such as the arrangement of the chips 110 and the spacing between the chips 110. For example, in the packaging structure, the second connecting portion 123 of all the heat-conducting pillars 120 is configured such that the side facing the middle region of the chip 110 is an inclined surface and the side away from the middle region of the chip 110 is a vertical surface; or some of the second connecting portions 123 of the heat-conducting pillars 120 are configured such that the side facing the middle region of the chip 110 is an inclined surface and the side away from the middle region of the chip 110 is a vertical surface, and another part of the second connecting portions 123 of the heat-conducting pillars 120 are configured such that all sides are inclined or vertical.

[0090] In some specific embodiments, the heat dissipation performance of the packaging structure is further enhanced by providing a thermally conductive layer 190. For example, such as... Figure 9The diagram shown is a schematic of the packaging structure provided in the ninth embodiment of the present invention. In the ninth embodiment, the packaging structure further includes a thermally conductive layer 190, which covers the lower surface of the base island 101. The base island 101 transfers heat to the thermally conductive layer 190, and the heat is exchanged with an external heat dissipation module (such as heat sink fins, liquid cooling pipes, or heat pipe systems) through the thermally conductive layer 190. In this embodiment, the thermally conductive layer 190 not only covers the lower surface of the base island 101 but also covers the entire lower surface of the pre-molded body 170. In other embodiments, the packaging structure does not include the pre-molded body 170, in which case the thermally conductive layer 190 covers the entire lower surface of the molded body 150, greatly increasing the heat dissipation area of ​​the packaging structure and thus improving its heat dissipation performance. In another embodiment, the thermally conductive layer 190 covers only the lower surface of the base island 101. In yet another embodiment, the thermally conductive layer 190 covers both the lower surface of the base island 101 and a portion of the lower surface of the pre-molded enclosure 170, to balance heat dissipation performance and packaging cost. In yet another embodiment, the packaging structure does not include the pre-molded enclosure 170, in which case the thermally conductive layer 190 covers a portion of the lower surface of the molded enclosure 150. The material of the thermally conductive layer 190 is the same as the material of the base island 101, or the material of the thermally conductive layer 190 is a material with a thermal conductivity greater than that of the base island 101, such as graphene. In one embodiment, the material of the thermally conductive layer 190 is the same as the material of the conductive pad 160, and both can be formed in the same step to reduce packaging steps, thereby simplifying the packaging process and reducing packaging costs.

[0091] The packaging structure provided in this specific embodiment of the invention optimizes the heat conduction path and improves the support for the stacked chips 110 through the design of the heat-conducting pillars 120, reducing the requirements for the spacing between chips 110 to meet the stability requirements of the packaging structure. The size design of the first connecting part 121 and the second connecting part 123 of the heat-conducting pillars 120 increases the contact area between the chips 110 and the base island 101, realizing heat transfer between the chips 110 and the base island 101, better carrying away the heat of the chips 110, and the thermally conductive adhesive 104 preferentially climbs along the sloping side without overflowing and contaminating other areas of the chips 110. The groove 103 of the base island 101 improves the positioning of the dispensing and the placement of the heat-conducting pillars 120, and increases the contact area between the thermally conductive adhesive 104 and the heat-conducting pillars 120, improving the thermal conductivity. The addition of a thermally conductive layer 190 further increases the heat dissipation area, further solving the problem of heat dissipation difficulty of the stacked chips 110.

[0092] Based on the same inventive concept, this invention also provides a method for forming the above-mentioned packaging structure. For example... Figure 12The diagram illustrates the steps of a method for forming a package structure according to a first specific embodiment of the present invention. Step S100: A lead frame 100 is provided, comprising a base island 101 and pins 102 disposed around the base island 101. Step S110: A heat-conducting pillar 120 is disposed on the upper surface of the base island 101, the heat-conducting pillar 120 being vertically disposed on the base island 101. Step S120: Chips 110 are mounted on the upper surface of the base island 101, with multiple chips 110 stacked along a direction perpendicular to the lead frame 100, and at least some of the chips 110 being offset along a direction parallel to the lead frame 100, such that a portion of the chips 110 is suspended above the base island 101, and one end of the heat-conducting pillar 120 away from the base island 101 contacts the suspended region 111 of the chip 110. Step S130: A first bonding wire 130 and a second bonding wire 140 are formed. The first bonding wire 130 electrically connects the chips 110 to each other and connects the chips 110 to the pins 102. One end of the second bonding wire 140 is connected to the pins 102 and extends in a direction perpendicular to the upper surface of the pins 102. In step S140, molding is performed to form a molding compound 150. The molding compound 150 covers the lead frame 100, the chips 110, the heat-conducting pillars 120, the first bonding wire 130, and the second bonding wire 140. The molding compound 150 does not cover the lower surface of the base island 101 or the other end of the second bonding wire 140. In step S150, a conductive connection pad 160 is formed on the upper surface of the molding compound 150. The conductive connection pad 160 is electrically connected to the other end of the second bonding wire 140.

[0093] Figures 13-20 This is a process flow diagram of the method for forming the packaging structure provided in the first specific embodiment of the present invention. The method for forming the packaging structure of the present invention will be described in detail below with reference to the accompanying drawings.

[0094] Please see Figures 13-15 ,in, Figure 13 This is a schematic diagram of the lead frame substrate 300 in the method for forming the packaging structure provided in the first specific embodiment of the present invention. Figure 14 This is a schematic diagram of the lead frame 100 in the method for forming the packaging structure provided in the first specific embodiment of the present invention. Figure 15This is a schematic diagram of the pre-molding of the lead frame 100 in the method for forming the packaging structure provided in the first specific embodiment of the present invention. Step S100: Provide the lead frame 100, which includes a base island 101 and pins 102 disposed around the base island 101. The base island 101 is used to support the chip 110 and provide stable mechanical support. The pins 102 are distributed circumferentially along the base island 101 at equal or gradient intervals. There is a gap between the pins 102 and the base island 101, that is, the pins 102 are not connected to the base island 101 to avoid the pins 102 and the base island 101 conducting electricity.

[0095] In this specific embodiment, the step of providing the lead frame 100 further includes: Please refer to Figure 13 Provides lead frame substrate 300; please refer to Figure 14 The lead frame substrate 300 is etched to form the base island 101 and the pin 102; see also Figure 15 The pre-molding process involves filling a pre-molded body 170 between the base island 101 and the pins 102; the molding process, forming a molded body 150, further includes the molded body 150 covering the surface of the pre-molded body 170. This method of forming the present invention pre-moldes the lead frame 100 before stacking the chips 110, which improves the strength of the lead frame 100 and avoids deformation of the lead frame 100 in subsequent process steps, thus preventing issues with the reliability of the package structure.

[0096] In this specific embodiment, when the lead frame substrate 300 is etched, the pin 102 is also partially etched. Therefore, in the pre-molding step, the pre-molding body 170 covers the lower surface of the pin 102 and fills the space between the pin 102 and the base island 101. The upper surface of the pin 102, the upper surface of the base island 101, and the lower surface of the base island 101 are not covered by the pre-molding body 170. In another specific embodiment, when the lead frame substrate 300 is etched, the pin 102 is not etched. Therefore, in the pre-molding step, the pre-molding body 170 fills the space between the pin 102 and the base island 101. The upper surface of the pin 102, the lower surface of the pin 102, the upper surface of the base island 101, and the lower surface of the base island 101 are not covered by the pre-molding body 170. Please refer to [link to previous embodiment]. Figure 2 .

[0097] In some specific embodiments, this step further includes forming a groove 103 on the upper surface of the base island 101. Specifically, the groove 103 is formed simultaneously on the upper surface of the base island 101 during the etching step of the lead frame substrate 300. The location of the groove 103 is the location where the heat-conducting pillars 120 need to be subsequently installed.

[0098] Please see Figure 16 This is a schematic diagram of the method for forming a packaging structure according to the first specific embodiment of the present invention, in which a heat-conducting pillar 120 is set on the upper surface of the base island 101. The heat-conducting pillar 120 is vertically set on the base island 101. The setting position of the heat-conducting pillar 120 corresponds to the suspended region 111 of the subsequently formed chip 110.

[0099] In one specific embodiment, the step further includes: placing the heat-conducting pillar 120 within the groove 103; and filling the groove 103 with thermally conductive adhesive 104 to fix the heat-conducting pillar 120. In this specific embodiment, the heights of the plurality of heat-conducting pillars 120 may be different to accommodate chips 110 located at different heights.

[0100] In one specific embodiment, the heat-conducting pillar 120 includes a first connecting portion 121, a pillar 122, and a second connecting portion 123 arranged along a direction perpendicular to the lead frame 100. The cross-sectional area of ​​the first connecting portion 121 is larger than the cross-sectional area of ​​the pillar 122 and / or the cross-sectional area of ​​the second connecting portion 123 is larger than the cross-sectional area of ​​the pillar 122. Please refer to [link to relevant documentation]. Figure 6 The step of providing heat-conducting pillars 120 on the upper surface of the base island 101 further includes: contacting the first connecting portion 121 with the base island 101. Specifically, all or part of the first connecting portion 121 is placed in the groove 103 on the upper surface of the base island 101, and the bottom surface of the first connecting portion 121 is in contact with the bottom surface of the groove 103.

[0101] In one specific embodiment, the side surface of the first connecting portion 121 is an inclined surface; please refer to [reference needed]. Figure 7 The step of providing heat-conducting pillars 120 on the upper surface of the base island 101 further includes: placing all or part of the inclined surface of the first connecting portion 121 within the groove 103 on the upper surface of the base island 101. In a specific embodiment, the side of the second connecting portion 123 facing the middle region of the chip 110 is an inclined surface, and the side away from the middle region of the chip 110 is a vertical surface. Please refer to [link to relevant documentation]. Figure 8 .

[0102] Please see Figure 17This is a schematic diagram of the chip mounting 110 in the packaging structure formation method provided in the first specific embodiment of the present invention. In step S120, the chip 110 is mounted on the upper surface of the base island 101. Multiple chips 110 are stacked along a direction perpendicular to the lead frame 100, and at least some of the chips 110 are staggered along a direction parallel to the lead frame 100, so that a portion of these chips 110 is suspended above the base island 101, and the end of the thermally conductive pillar 120 away from the base island 101 contacts the suspended area 111 of the chip 110. In one specific embodiment, a thermally conductive adhesive layer 113 is formed on the lower surface of the chip 110, and adjacent chips 110 are bonded together through the thermally conductive adhesive layer 113. The end of the thermally conductive pillar 120 away from the base island 101, that is, the second connecting portion 123 of the thermally conductive pillar 120, contacts the thermally conductive adhesive layer 113.

[0103] In this step, the bottommost chip 110 is first mounted. The bottommost chip 110 is mounted on the base island 101 through a thermally conductive adhesive layer 113. Then, the upper layer chips 110 are mounted sequentially. The upper layer chips 110 are mounted on the upper surface of the chip 110 below them through a thermally conductive adhesive layer 113, and are offset from the lower chip 110. The area of ​​the lower chip 110 that needs to be connected to the first bonding wire 130 is exposed. The offset area of ​​the upper chip 110 serves as the suspended area 111. The suspended area 111 is mounted on the end face of the second connecting part 123 of the thermally conductive pillar 120 through the thermally conductive adhesive layer 113. That is, the second connecting part 123 of the thermally conductive pillar 120 is in contact with the suspended area 111 of the chip 110.

[0104] In this step, multiple chips 110 have various stacking methods to meet different packaging requirements.

[0105] like Figure 17As shown, in this specific embodiment, a first chip stack structure 180 and a second chip stack structure 181 are formed on the upper surface of the base island 101 along a direction parallel to the lead frame 100. The chips 110 in the first chip stack structure 180 and the second chip stack structure 181 are staggered in opposite directions. Specifically, the first chip stack structure 180 includes a plurality of chips 110 staggered to the right, and the second chip stack structure 181 includes a plurality of chips 110 staggered to the left. The first chip stack structure 180 and the second chip stack structure 181 contain the same number of chips 110. In other specific embodiments, the first chip stack structure 180 and the second chip stack structure 181 contain different numbers of chips 110. In another specific embodiment, multiple sets of first chip stack structures 180 and second chip stack structures 181 may also be provided along a direction parallel to the lead frame 100. After forming a first chip stack structure 180 and a second chip stack structure 181 arranged in a direction parallel to the lead frame 100 on the upper surface of the base island 101, the method further includes: forming a top chip 182 on the first chip stack structure 180 and the second chip stack structure 181, wherein the two edges of the lower surface of the top chip 182 are respectively bonded to the uppermost chip 110 of the first chip stack structure 180 and the uppermost chip 110 of the second chip stack structure 181 through a thermally conductive adhesive layer 113, and the middle region of the top chip 182 is suspended above the base island 101 and in contact with the thermally conductive pillar 120.

[0106] like Figure 5 As shown, in another specific embodiment, a first chip stacking structure 180 and a second chip stacking structure 181 are formed on the upper surface of the base island 101 in a direction parallel to the lead frame 100, wherein the chips 110 in the first chip stacking structure 180 and the second chip stacking structure 181 are arranged in the same direction with the chips 110 offset from each other.

[0107] like Figure 3 As shown, in another specific embodiment, the step of mounting the chip 110 on the upper surface of the base island 101 further includes: sequentially staggering the chips 110 along a direction parallel to the lead frame 100, with all or part of the suspended areas 111 of the chips 110 in contact with the heat-conducting pillars 120. Multiple chips 110 form a chip stack structure, with all chips 110 staggered along a direction parallel to the lead frame 100, and the chips 110 connected by a thermally conductive adhesive layer 113. Except for the bottommost chip 110, each chip 110 has a suspended area 111, and each suspended area 111 is in contact with one or more heat-conducting pillars 120.

[0108] like Figure 4 As shown, in another specific embodiment, the step of mounting the chip 110 on the upper surface of the base island 101 further includes: forming a plurality of chip groups 400 on the upper surface of the base island 101, wherein each chip group 400 includes one or more chips 110, and the number of chips 110 in different chip groups 400 is the same or different, the chips 110 in the same chip group 400 are aligned along the direction parallel to the lead frame 100, the chip groups 400 are staggered along the direction parallel to the lead frame 100, and the heat-conducting pillar 120 contacts the suspended area 111 of the chip group 400, that is, the heat-conducting pillar 120 contacts the suspended area 111 of the bottommost chip 110 in the chip group 400, so as to realize the heat conduction of the chip group 400.

[0109] Furthermore, in one specific embodiment, the side of the second connecting portion 123 of the heat-conducting pillar 120 facing the middle region of the chip 110 is inclined, while the side away from the middle region of the chip 110 is vertical, such as... Figure 8 As shown, the step of mounting the chip 110 on the upper surface of the base island 101 further includes: when mounting the chip 110, making the side of the chip 110 flush with the side sheet of the second connection portion 123 of the heat-conducting pillar 120.

[0110] Furthermore, in some specific embodiments, the step of mounting the chip 110 on the upper surface of the base island 101 further includes: arranging the chip 110 such that the chip 110 with the suspended region 111 is correspondingly arranged with the heat-conducting pillar 120, or the same chip 110 with the suspended region 111 is correspondingly arranged with multiple heat-conducting pillars 120, so as to optimize the heat conduction path of the chip 110.

[0111] Please see Figure 18 and Figure 19 ,in, Figure 18 This is a schematic diagram of the formation of the first bonding wire 130 in the method for forming the packaging structure provided in the first specific embodiment of the present invention. Figure 19 This is a schematic diagram of forming a second bonding wire 140 in the method for forming a package structure provided in the first specific embodiment of the present invention. In step S130, a first bonding wire 130 and a second bonding wire 140 are formed. The first bonding wire 130 electrically connects the chips 110 to each other and electrically connects the chips 110 to the pins 102. One end of the second bonding wire 140 is connected to the pins 102 and extends in a direction perpendicular to the upper surface of the pins 102.

[0112] In this step, such as Figure 18As shown, a first wire bonding process is performed to form the first bonding wire 130. In this step, multiple first bonding wires 130 are formed. A portion of the first bonding wires 130 are used to electrically connect the chips 110 together, and another portion of the first bonding wires 130 are used to electrically connect the chips 110 to the pins 102.

[0113] In this step, such as Figure 19 As shown, after the first bonding wire 130 is formed, a vertical wire bonding process is performed to form the second bonding wire 140. The second bonding wire 140 is a vertical bonding wire.

[0114] Please see Figure 20 This is a schematic diagram of forming a molding compound 150 in the method for forming a packaging structure provided in the first specific embodiment of the present invention. Step S140 involves molding to form the molding compound 150. The molding compound 150 covers the lead frame 100, the chip 110, the heat-conducting pillar 120, the first bonding wire 130, and the second bonding wire 140, but does not cover the lower surface of the base island 101 or the other end of the second bonding wire 140. In this step, the molding compound 150 also covers the surface of the pre-molded compound 170. In this step, the molding compound 150 may first cover the end of the second bonding wire 140, and then the molding compound 150 may be thinned through a grinding process until the end of the second bonding wire 140 is exposed.

[0115] The molding process involves placing the chip 110 and lead frame 100 in a mold cavity, injecting preheated epoxy molding compound (EMC), filling the cavity under molding pressure, and then maintaining the temperature and pressure at a constant temperature to complete cross-linking and curing, forming a package that provides mechanical protection and electrical isolation. The molded package 150 has good mechanical strength, thermal stability, and moisture resistance, effectively protecting the internal structure from the effects of the external environment (such as moisture, dust, mechanical stress, etc.), while providing structural support for subsequent cutting, testing, and assembly processes.

[0116] Please see Figure 1 In step S150, a conductive connection pad 160 is formed on the upper surface of the encapsulation body 150, and the conductive connection pad 160 is electrically connected to the other end of the second bonding wire 140.

[0117] As an example, the process of forming the conductive pad 160 on the upper surface of the molding compound 150 mainly includes: first, performing laser or chemical pretreatment on the surface of the molding compound 150 to clean and increase roughness; then, depositing a seed layer using physical vapor deposition or chemical plating; exposing the area to be electroplated by photolithography patterning; subsequently, electroplating to deposit metal layers such as copper, nickel, and gold to form the conductive pad 160; finally, annealing or surface passivation treatment can be performed to improve performance.

[0118] In another specific embodiment, the step of forming the conductive connection pad 160 on the upper surface of the molding compound 150 further includes: Please refer to Figure 9 A thermally conductive layer 190 is formed, which at least covers the lower surface of the base island 101. In this step, the thermally conductive layer 190 is formed simultaneously with the conductive connection pad 160, without the need for additional process steps, simplifying the preparation process and reducing manufacturing costs.

[0119] In another specific embodiment, the thermally conductive layer 190 may be formed after the step of forming the conductive connection pad 160 on the upper surface of the encapsulation body 150. The thermally conductive layer 190 may be made of a different material than the conductive connection pad 160. For example, the thermally conductive layer 190 may be made of a material with a higher thermal conductivity to further improve the thermal conductivity of the encapsulation structure and thus improve the heat dissipation performance of the encapsulation structure.

[0120] The forming method provided by the specific embodiments of the present invention can form heat-conducting pillars in the package structure. When the chip is working, part of the heat generated is first conducted to the suspended area of ​​the chip. This suspended area forms a local low temperature zone due to the absence of thermal interference from adjacent chips. The heat is rapidly transferred vertically to the base island through the heat-conducting pillars here. Another part of the heat is directly transferred to the base island through the bottom chip. Finally, the base island and the external heat dissipation module (such as heat sink fins, liquid cooling pipes or heat pipe systems) complete the heat exchange. The present invention optimizes the heat conduction path of the package structure and greatly improves the heat dissipation performance of the package structure.

[0121] It should be noted that references to "an embodiment," "an embodiment," "an exemplary embodiment," "some embodiments," etc., in the specification indicate that the described embodiments may include specific features, structures, or characteristics, but each embodiment may not necessarily include that specific feature, structure, or characteristic. Furthermore, such phrases do not necessarily refer to the same embodiment. In addition, when a specific feature, structure, or characteristic is described in connection with an embodiment, whether explicitly described or not, implementing such a feature, structure, or characteristic in conjunction with other embodiments is within the knowledge of those skilled in the art.

[0122] It should be noted that the terms "comprising" and "having," and their variations, used in this invention document are intended to cover non-exclusive inclusion. The terms "first," "second," etc., are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence, unless explicitly indicated by the context. It should be understood that such data used interchangeably where appropriate. Furthermore, embodiments and features within embodiments of this invention can be combined with each other unless otherwise specified. In addition, descriptions of well-known components and technologies have been omitted in the above description to avoid unnecessarily obscuring the concepts of this invention. In the various embodiments described above, each embodiment focuses on its differences from other embodiments; similar or identical parts between embodiments can be referred to interchangeably.

[0123] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A package structure, characterized by, include: A lead frame, including a base island and pins disposed around the base island; Multiple chips are stacked on the surface of the base island along a direction perpendicular to the lead frame, and at least some of the chips are offset along a direction parallel to the lead frame, such that a portion of the chips are suspended above the base island. Multiple heat-conducting pillars are vertically arranged on the base island, with one end of each pillar disposed on the surface of the base island and the other end in contact with the suspended area of ​​the chip. The first bonding wire electrically connects the chips to each other and electrically connects the chips to the pins; The second bonding wire is connected to the pin at one end and extends in a direction perpendicular to the upper surface of the pin; A molding compound covers the lead frame, the chip, the thermal pillar, the first bonding wire, and the second bonding wire, but the molding compound does not cover the lower surface of the base island or the other end of the second bonding wire; A conductive connection pad is disposed on the upper surface of the encapsulation body and electrically connected to the other end of the second bonding wire.

2. The package structure of claim 1, wherein, The lead frame also includes a pre-molded body that fills the space between the pins and the base island, and the molded body also covers the surface of the pre-molded body.

3. The package structure of claim 1 or 2, wherein, The lower surface of the pin is covered by the molding compound, and when the lead frame includes the pre-molded compound, the lower surface of the pin is covered by the pre-molded compound.

4. The packaging structure according to claim 3, characterized in that, The lower surface of the pin is higher than the lower surface of the base island.

5. The packaging structure according to claim 1 or 2, characterized in that, The lower surface of the pin is not covered by the molding compound. When the lead frame includes the pre-molded compound, the lower surface of the pin is not covered by the pre-molded compound.

6. The packaging structure according to claim 5, characterized in that, The lower surface of the pin is flush with the lower surface of the base island.

7. The package structure of claim 1, wherein, The lower surface of the chip has a thermally conductive adhesive layer, and adjacent chips are bonded together through the thermally conductive adhesive layer. The other end of the thermally conductive pillar is in contact with the thermally conductive adhesive layer.

8. The package structure of claim 1, wherein, All of the chips are offset along a direction parallel to the lead frame.

9. The package structure of claim 8, wherein, All or part of the suspended area of ​​the chip is in contact with the heat-conducting pillar.

10. The package structure of claim 1, wherein, The packaging structure includes multiple chipsets, each chipset including one or more chips. The chips within the same chipset are aligned along a direction parallel to the lead frame, and the chipsets are staggered along a direction parallel to the lead frame. The heat-conducting pillars are in contact with the suspended area of ​​the chipset.

11. The package structure of claim 10, wherein, The number of chips in different chipsets may be the same or different.

12. The package structure of claim 1, wherein, The packaging structure includes a first chip stack structure and a second chip stack structure arranged in a direction parallel to the lead frame, wherein the chips in the first chip stack structure and the second chip stack structure are arranged in opposite directions.

13. The package structure of claim 12, wherein, The packaging structure also includes a top-layer chip, the two edges of the lower surface of which are respectively bonded to the top-layer chip of the first chip stack structure and the top-layer chip of the second chip stack structure through a thermally conductive adhesive layer.

14. The package structure of claim 13, wherein, The middle region of the top-layer chip is suspended above the base island and in contact with the heat-conducting pillar.

15. The package structure of claim 1, wherein, The heat-conducting pillars are configured in a one-to-one correspondence with the chips having suspended areas.

16. The package structure of claim 1, wherein, Multiple heat-conducting pillars are respectively arranged corresponding to the chip with the same suspended area.

17. The packaging structure according to claim 1, characterized in that, The surface of the base island has a groove, one end of the heat-conducting pillar is disposed in the groove, and thermally conductive adhesive is filled in the groove to fix the heat-conducting pillar.

18. The package structure of claim 1, wherein, The heat-conducting pillar includes a first connecting portion, a pillar, and a second connecting portion arranged along a direction perpendicular to the lead frame. The first connecting portion contacts the base island, and the second connecting portion contacts the suspended area of ​​the chip. The cross-sectional area of ​​the first connecting portion is larger than the cross-sectional area of ​​the pillar.

19. The package structure of claim 18, wherein, The side of the first connecting part is an inclined surface.

20. The package structure of claim 19, wherein, The surface of the base island has a groove, one end of the heat-conducting pillar is disposed in the groove, and the heat-conducting adhesive is filled in the groove to fix the heat-conducting pillar. The inclined surface is partially located in the groove and the other part is located outside the groove, or the entire inclined surface is located in the groove.

21. The package structure of claim 18, wherein, The cross-sectional area of ​​the second connecting part is larger than the cross-sectional area of ​​the column.

22. The package structure of claim 21, wherein, The side of the second connecting part is an inclined surface.

23. The package structure of claim 21, wherein, The side of the second connecting portion facing the middle region of the chip is an inclined surface, and the side away from the middle region of the chip is a vertical surface.

24. The package structure of claim 23, wherein, The side of the second connecting portion away from the middle region of the chip is flush with the side of the pillar and also flush with the side of the chip.

25. The package structure of claim 1, wherein, The package includes multiple first bonding wires, a portion of which are used to electrically connect the chips to each other, and another portion of which are used to electrically connect the chips to the pins.

26. The packaging structure according to claim 1 or 2, characterized in that, The packaging structure also includes a thermally conductive layer that covers the lower surface of the base island.

27. The package structure of claim 26, wherein, When the lead frame does not include the pre-molded body, the thermally conductive layer also covers all or part of the lower surface of the molded body; when the lead frame includes the pre-molded body, the thermally conductive layer also covers all or part of the lower surface of the pre-molded body.

28. A method of forming a package structure, comprising: include: A lead frame is provided, the lead frame including a base island and pins disposed around the base island; A heat-conducting pillar is provided on the upper surface of the base island, and the heat-conducting pillar is vertically arranged on the base island. Chips are mounted on the surface of the base island, and multiple chips are stacked in a direction perpendicular to the lead frame. At least some of the chips are offset in a direction parallel to the lead frame, so that a portion of the chips are suspended above the base island, and the end of the heat-conducting pillar away from the base island contacts the suspended portion of the chip. A first bonding wire and a second bonding wire are formed. The first bonding wire electrically connects the chips to each other and connects the chips to the pins. One end of the second bonding wire is connected to the pin and extends in a direction perpendicular to the upper surface of the pin. Molding is performed to form a molding compound that encapsulates the lead frame, the chip, the thermal pillars, the first bonding wire, and the second bonding wire, but the molding compound does not cover the lower surface of the base island or the other end of the second bonding wire. A conductive connection pad is formed on the upper surface of the encapsulation body, and the conductive connection pad is electrically connected to the other end of the second bonding wire.

29. The method of claim 28, wherein The step of providing the lead frame further includes: Provide lead frame substrate; The lead frame substrate is etched to form the base island and the pins; Pre-molding to fill the space between the base island and the pins; The step of molding, forming a molded body, further includes: the molded body also covering the surface of the pre-molded body.

30. The method of claim 29, wherein In the step of etching the lead frame substrate, the pin is partially etched; in the step of pre-molding, the pre-molding body also covers the lower surface of the pin.

31. The method of claim 28, wherein Before the step of setting the heat-conducting pillar on the upper surface of the base island, the method includes: forming a groove on the upper surface of the base island; the step of setting the heat-conducting pillar on the upper surface of the base island further includes: placing the heat-conducting pillar in the groove; and filling the groove with thermally conductive adhesive to fix the heat-conducting pillar.

32. The method of claim 28, wherein The heat-conducting pillar includes a first connecting portion, a pillar, and a second connecting portion arranged along a direction perpendicular to the lead frame. The cross-sectional area of ​​the first connecting portion is larger than the cross-sectional area of ​​the pillar and / or the cross-sectional area of ​​the second connecting portion is larger than the cross-sectional area of ​​the pillar. The step of setting the heat-conducting pillar on the surface of the base island further includes: contacting the first connecting portion with the base island; the step of mounting the chip on the surface of the base island further includes: contacting the second connecting portion with the suspended area of ​​the chip.

33. The method of claim 32, wherein The step of setting heat-conducting pillars on the surface of the base island, wherein the side of the first connecting part is an inclined surface, further includes: placing all or part of the inclined surface of the first connecting part in the groove on the surface of the base island.

34. The method of forming a package structure of claim 32, wherein, The side of the second connecting portion facing the middle region of the chip is an inclined surface, and the side away from the middle region of the chip is a vertical surface; the step of mounting the chip on the surface of the base island further includes, when mounting the chip, making the side of the chip flush with the side plate of the second connecting portion of the heat-conducting pillar.

35. The method of claim 28, wherein The step of mounting chips on the upper surface of the base island further includes: forming a thermally conductive adhesive layer on the lower surface of the chip, bonding adjacent chips together through the thermally conductive adhesive layer, and having one end of the thermally conductive pillar away from the base island contact the thermally conductive adhesive layer.

36. The method of forming a package structure of claim 28, wherein The step of mounting chips on the surface of the base island further includes: sequentially staggering the chips along a direction parallel to the lead frame, with all or part of the suspended areas of the chips in contact with the heat-conducting pillars.

37. The method of claim 36, wherein The step of mounting chips on the surface of the base island further includes: forming multiple chip groups on the surface of the base island, each chip group including one or more chips, the number of chips in different chip groups being the same or different, the chips in the same chip group being aligned along a direction parallel to the lead frame, the chip groups being staggered along a direction parallel to the lead frame, and the heat-conducting pillars contacting the suspended area of ​​the chip groups.

38. The method of forming a package structure of claim 28, wherein, The step of mounting chips on the surface of the base island further includes: forming a first chip stack structure and a second chip stack structure on the surface of the base island along a direction parallel to the lead frame, wherein the chips in the first chip stack structure and the second chip stack structure are arranged in opposite directions.

39. The method of claim 38, wherein After the step of forming a first chip stack structure and a second chip stack structure arranged parallel to the lead frame direction on the upper surface of the base island, the method further includes: forming a top chip on the first chip stack structure and the second chip stack structure, wherein the two edges of the lower surface of the top chip are respectively bonded to the top chip of the first chip stack structure and the top chip of the second chip stack structure through a thermally conductive adhesive layer, and the middle region of the top chip is suspended above the base island and in contact with the thermally conductive pillar.

40. The method of claim 28, wherein The step of mounting chips on the surface of the base island further includes: arranging the chips such that the chips with suspended areas are arranged in a one-to-one correspondence with the heat-conducting pillars.

41. The method for forming the packaging structure according to claim 28, characterized in that, The step of mounting the chip on the surface of the base island further includes: arranging the chip so that the chip with the same suspended area is correspondingly arranged with the plurality of heat-conducting pillars.

42. The method for forming the packaging structure according to claim 28, characterized in that, The steps of forming the first bonding wire and the second bonding wire further include: Perform the first wire bonding process to form the first bond wire; Perform a vertical wire bonding process to form the second bond wire.

43. The method for forming the packaging structure according to claim 28, characterized in that, The step of forming a conductive connection pad on the upper surface of the molding compound, or the step of forming a conductive connection pad on the upper surface of the molding compound, further includes: forming a thermally conductive layer, the thermally conductive layer at least covering the lower surface of the base island.

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