Packaging structure and forming method thereof

Abstract

The invention relates to a packaging structure and a forming method thereof. The packaging structure comprises a lead frame, the lead frame comprises a base island and pins located on the outer side of the base island, the base island comprises a front face and a back face which are oppositely distributed, and the pins extend in the direction perpendicular to the front face of the base island; the first chip is mounted on the front surface of the base island, and the first chip is electrically connected with the pins; and the second chip is mounted on the side wall of the pin, and the second chip is electrically connected with the pin. According to the invention, more chips can be mounted in the limited space of the packaging structure, so that the integration level of the packaging structure is increased, and the heat dissipation performance of the packaging structure is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing technology, and in particular to a packaging structure and a method for forming the same. Background Technology

[0002] With the continuous evolution of advanced packaging technologies, wafer-level packaging (WLP) has become increasingly widely used. WLP enables higher-density integration (including higher density and more functions) within a limited space, making it possible to implement a complete system within a single package. For example, packaging technology has evolved from traditional 2D packaging to 2.5D and 3D packaging technologies. As packaging technology develops, packaging structures are also becoming increasingly complex. QFN (Quad Flat No.) A Quad Flat No-Lead (QFN) package is a common packaging structure. The QFN package structure offers advantages such as good electrical and thermal performance, small size, light weight, and low development cost, making it suitable for high-density printed circuit boards in mobile phones, digital cameras, PDAs, and other portable small electronic devices. The QFN package structure includes a base island and pins arranged around its outer perimeter.

[0003] With the increasing demand for highly integrated packaged products, there is a desire to integrate more chips into the package structure. However, the more chips integrated, the worse the heat dissipation performance of the package structure becomes. It is difficult to achieve both, thus limiting the further development of package structures.

[0004] Therefore, how to improve the heat dissipation performance of the packaging structure while increasing its integration level, thereby expanding the application areas of the packaging structure, is a technical problem that urgently needs to be solved. Summary of the Invention

[0005] This invention provides a packaging structure and a method for forming the same, which can improve the heat dissipation performance of the packaging structure while increasing the integration level, thereby expanding the application fields of the packaging structure.

[0006] According to some embodiments, the present invention provides a packaging structure, including: A lead frame includes a base island and pins located outside the base island, the base island including a front and a back side oppositely distributed, the pins extending in a direction perpendicular to the front side of the base island; The first chip is mounted on the front side of the base island, and the first chip is electrically connected to the pins; The second chip is mounted on the sidewall of the pin and is electrically connected to the pin.

[0007] In some embodiments, the pin includes a body portion extending in a direction perpendicular to the front of the base island, the body portion including an inner sidewall facing the base island and an outer sidewall facing away from the base island; The second chip is flip-mounted onto the outer side wall of the main body.

[0008] In some embodiments, the pin further includes a platform portion that protrudes from the inner sidewall of the body portion; The packaging structure also includes leads, one end of which is electrically connected to the first chip and the other end of which is electrically connected to the platform section.

[0009] In some embodiments, the width of the front side of the base island is smaller than the width of the back side of the base island.

[0010] In some embodiments, the cross-section of the base island is trapezoidal; or, The base island includes a lower step and an upper step protruding from the lower step, wherein the width of the upper step is smaller than the width of the lower step.

[0011] In some embodiments, the lead frame further includes: The pre-encapsulation layer includes a filler portion filling between the pin and the base island, and an extension connected to the outer sidewall of the body portion, wherein the side of the second chip is located on the extension.

[0012] In some embodiments, the extension includes an upper surface and a lower surface that are oppositely distributed, and the second chip is located on the flat upper surface of the extension.

[0013] In some embodiments, the extension includes an upper surface and a lower surface that are oppositely distributed, and the extension has a groove recessed from the upper surface toward the interior of the extension, the second chip portion being inserted into the groove.

[0014] In some embodiments, the back side of the second chip abuts against the sidewall of the groove.

[0015] In some embodiments, the width of the groove is equal to or greater than the thickness of the second chip, and the side end of the second chip is secured within the groove.

[0016] In some embodiments, it also includes: A molding compound is located above the lead frame, and the molding compound at least molds the first chip, the second chip, and the pins, and the top surface of the molding compound is flush with the top surface of the pins.

[0017] In some embodiments, the material of the molding layer is the same as the material of the pre-encapsulation layer.

[0018] In some embodiments, it also includes: The third chip is mounted on the inner sidewall of the main body, and the third chip is electrically connected to the pin.

[0019] In some embodiments, the second chip and the third chip are aligned; or... The second chip and the third chip are staggered.

[0020] According to other embodiments, the present invention also provides a method for forming an encapsulation structure, comprising the following steps: A lead frame is formed, the lead frame including a base island and pins located outside the base island, the base island including a front side and a back side opposite to each other, and the pins extending in a direction perpendicular to the front side of the base island; A first chip is mounted on the front side of the base island, and a second chip is mounted on the side wall of the pin, with both the first chip and the second chip being electrically connected to the pin.

[0021] In some embodiments, the specific steps for forming the lead frame include: Provide frame materials; The frame material is patterned to form an initial frame including the base island and the pins located outside the base island; The initial frame is pre-encapsulated to form a pre-encapsulation layer.

[0022] In some embodiments, the specific steps of patterning the frame material to form an initial frame including the base island and the pins located outside the base island include: The frame material is patterned to form the base island and the pins including a body portion extending in a direction perpendicular to the front of the base island, the body portion including an inner sidewall facing the base island and an outer sidewall facing away from the base island.

[0023] In some embodiments, the pin further includes a platform portion that protrudes from the inner sidewall of the body portion.

[0024] In some embodiments, the width of the front side of the base island is smaller than the width of the back side of the base island.

[0025] In some embodiments, the cross-section of the base island is trapezoidal; or, The base island includes a lower step and an upper step protruding from the lower step, wherein the width of the upper step is smaller than the width of the lower step.

[0026] In some embodiments, the specific steps of mounting a first chip to the front side of the base island and mounting a second chip to the sidewall of the pin, wherein both the first chip and the second chip are electrically connected to the pin, include: The first chip is mounted on the front side of the base island, and the first chip is electrically connected to the pins; The second chip is mounted on the outer side wall of the body and electrically connected to the pin.

[0027] In some embodiments, the specific steps of mounting the first chip onto the front side of the base island and electrically connecting the first chip to the pins include: The first chip is mounted on the front side of the base island with its functional surface facing away from the base island. A lead is formed to electrically connect the first chip to the platform portion of the pin.

[0028] In some embodiments, the pre-encapsulation layer includes a filling portion between the pin and the base island and an extension portion connected to the outer sidewall of the body portion, the extension portion including an upper surface and a lower surface oppositely distributed; the specific steps of mounting the second chip to the outer sidewall of the body portion and electrically connecting the second chip to the pin include: The second chip is flipped onto the outer side wall of the body portion, such that the side of the second chip is located on the flat upper surface of the extension portion.

[0029] In some embodiments, the pre-encapsulation layer includes a filler portion filling between the pin and the base island, and an extension portion connected to the outer sidewall of the body portion. The extension portion includes an upper surface and a lower surface that are oppositely distributed, and the extension portion has a groove recessed from the upper surface into the interior of the extension portion. The specific steps of mounting the second chip to the outer sidewall of the body portion and electrically connecting the second chip to the pin include: The second chip is flipped onto the outer wall of the body portion, such that the second chip portion is inserted into the groove.

[0030] In some embodiments, after mounting the first chip onto the front side of the base island and mounting the second chip onto the sidewall of the pin, the following steps are further included: A third chip is mounted on the inner wall of the main body, and the third chip is electrically connected to the pin.

[0031] In some embodiments, after mounting the first chip onto the front side of the base island and mounting the second chip onto the sidewall of the pin, the following steps are further included: A molding layer is formed to encapsulate the first chip, the second chip, and the pins.

[0032] In some embodiments, after forming the molding layer encapsulating the first chip, the second chip, and the pins, the following steps are further included: The molding compound is planarized so that the top surface of the molding compound is flush with the top surface of the pin.

[0033] The packaging structure and its forming method provided by this invention, by setting the pins in the lead frame to extend in a direction perpendicular to the front surface of the base island (e.g., the front surface of the base island is horizontal, and the pins extend in a vertical direction), allows a first chip to be mounted on the front surface of the base island and a second chip to be mounted on the sidewalls extending vertically from the pins. This enables a larger number of chips to be mounted within the limited space of the packaging structure, increasing the integration density. Simultaneously, because the pins extend in a direction perpendicular to the front surface of the base island, the base island and the pins are located in different planes, allowing the base island and the pins to dissipate heat from different surfaces. For example, the base island can dissipate heat from the top and bottom, while the pins can dissipate heat from the side, significantly improving the heat dissipation performance of the packaging structure while increasing its integration density.

[0034] 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

[0035] 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.

[0036] Figure 1 This is a schematic diagram of the packaging structure in a specific embodiment of the present invention; Figure 2 This is another structural schematic diagram of the packaging structure in a specific embodiment of the present invention; Figure 3 This is another structural schematic diagram of the packaging structure in a specific embodiment of the present invention; Figure 4 This is a flowchart illustrating the method for forming the encapsulation structure in a specific embodiment of the present invention; Figure 5 This is a schematic diagram of a lead frame structure in a specific embodiment of the present invention; Figure 6 This is a schematic diagram of the structure after the first chip is mounted on the lead frame in a specific embodiment of the present invention; Figure 7 This is a schematic diagram of the structure after the second chip is mounted on the lead frame in a specific embodiment of the present invention; Figure 8 This is a schematic diagram of the structure after the molding layer is formed in a specific embodiment of the present invention; Figure 9 This is another structural schematic diagram of the lead frame in a specific embodiment of the present invention; Figure 10 This is another structural schematic diagram after the first chip is mounted on the lead frame in a specific embodiment of the present invention; Figure 11 This is another structural schematic diagram of the present invention after the second chip is mounted on the lead frame in a specific embodiment of the present invention; Figure 12 This is another structural diagram after the formation of the encapsulation layer in a specific embodiment of the present invention.

[0037] Explanation of reference numerals in the attached figures 10 base islands 11 pins 111 body part 112 Platform Department 13 First Chip 14 Adhesive Layer 15 Second Chip 16 Filling Section 17 Extension 18 solder balls 19 leads 20 sealing layers 21 grooves 22. Go down the steps 23. Climbing the steps 30 Third Chip 40 conductive bumps 101 Front 102 Back Detailed Implementation The specific embodiments of the packaging structure and its formation method provided by the present invention will be described in detail below with reference to the accompanying drawings.

[0038] This specific embodiment provides a packaging structure. Figure 1 This is a schematic diagram of the encapsulation structure in a specific embodiment of the present invention. For example... Figure 1 As shown, the packaging structure includes: A lead frame includes a base island 10 and pins 11 located outside the base island 10, the base island 10 including a front and a back side oppositely distributed, and the pins 11 extending in a direction perpendicular to the front side of the base island 10. The first chip 13 is mounted on the front side of the base island 10, and the first chip 13 is electrically connected to the pin 11; The second chip 15 is mounted on the side wall of the pin 11 and is electrically connected to the pin 11.

[0039] Specifically, the lead frame includes the base island 10 and a plurality of pins 11 distributed around the outer periphery of the base island 10. The base island 10 includes a front side and a back side distributed opposite to each other along a first direction D1, and the pins 11 extend along the first direction D1. In one example, the pins 11 include a top surface and a bottom surface distributed opposite to each other along the first direction D1, and along the first direction D1, the top surface of the pins 11 is higher than the front surface of the base island 10, and the bottom surface of the pins 11 is flush with the back surface of the base island 10. The sidewalls of the pins 11 connect between the top surface and the bottom surface of the pins 11. The first chip 13 is mounted on the front surface of the base island 10, and the second chip 15 is mounted on the sidewall of the pins 11. The first chip 13 may include a functional surface and a back side opposite to the functional surface, and the first chip 13 is mounted on the base island 10 with the functional surface facing away from the base island 10. In one example, there are multiple first chips 13, all of which are mounted on the front side of the base island 10 and are electrically connected to the pins 11. In this specific embodiment, "multiple" refers to two or more. In one example, the multiple first chips 13 have the same structure and function to further simplify the manufacturing process of the package structure. In another example, at least two of the first chips 13 have different structures or functions to further improve the integration of the package structure.

[0040] This specific embodiment increases the area of ​​the sidewall of the pin 11 by setting the pin 11 to extend in a direction perpendicular to the front surface of the base island 10. While ensuring the first chip 13 can be stably mounted on the base island 10, it also allows the second chip 15 to be mounted on the increased area of ​​the sidewall of the pin 11. This allows more chips to be mounted within the limited space of the package structure, increasing its integration density. Simultaneously, because the pin 11 extends in a direction perpendicular to the front surface of the base island 10, the front surface of the base island 10 and the sidewall of the pin 11 are in different planes. This allows the base island 10 and the pin 11 to dissipate heat from different surfaces, i.e., the base island 10 can dissipate heat from the top and bottom, while the pin 11 can dissipate heat from the side. This significantly improves the heat dissipation performance of the package structure while increasing its integration density.

[0041] In some embodiments, the pin 11 includes a body portion 111 that extends in a direction perpendicular to the front surface of the base island 10, and the body portion 111 includes an inner sidewall facing the base island 10 and an outer sidewall facing away from the base island 10. The second chip 15 is flip-mounted onto the outer side wall of the body portion 111.

[0042] For example, such as Figure 1 As shown, the pin 11 includes a body portion 111 extending in a direction perpendicular to the front surface of the base island 10. The bottom surface of the body portion 111 is flush with the back surface of the base island 10, and the top surface of the body portion 111 is higher than the front surface of the base island 10, thereby increasing the area of ​​the sidewalls of the pin 11 (including the inner sidewall and the outer sidewall of the pin 11). In one example, the body portion 111 is columnar. In a direction parallel to the front surface of the base island 10 (e.g.) Figure 1In the second direction (D2), the body portion 111 includes an inner sidewall facing the base island 10 and an outer sidewall facing away from the base island 10. The outer sidewall of the body portion 111 is a flat sidewall to facilitate stable mounting of the second chip 15 and simplify the manufacturing process of the pin 11. The second chip 15 is mounted on the outer sidewall of the body portion 111 with its functional surface facing the body portion 111; that is, the second chip 15 is flip-mounted onto the outer sidewall of the body portion 111. In one example, the functional surface of the second chip 15 has conductive connection posts, which are connected to the outer sidewall of the body portion 111 via solder balls 18. The conductive connection posts and solder balls 18 simultaneously establish an electrical connection between the second chip 15 and the body portion 111 of the pin 11, shortening the electrical connection distance between the second chip 15 and the pin 11 and ensuring reliable transmission of electrical signals between the pin 11 and the second chip 15.

[0043] This specific embodiment increases the distance between the second chip 15 and the first chip 13 mounted on the front side of the base island 10 by flip-mounting the second chip 15 onto the outer sidewall of the body portion 111. This avoids signal crosstalk between the first chip 13 and the second chip 15, ensuring the performance stability of the package structure. Furthermore, it provides more space for wire bonding connections between the first chip 13 and the pins 11, further simplifying the manufacturing process of the package structure. Simultaneously, by flip-mounting the second chip 15 onto the outer sidewall of the body portion 111, the second chip 15 is positioned vertically with its sidewall facing the lead frame, reducing the area occupied by the second chip 15 on the lead frame. Moreover, since the second chip 15 is flip-mounted onto the sidewall of the pins 11, the wire bonding process for electrically connecting the second chip 15 to the pins 11 is eliminated. This not only further improves the performance of the package structure but also simplifies the manufacturing process and increases manufacturing efficiency.

[0044] In some embodiments, the pin 11 further includes a platform portion 112, which protrudes from the inner sidewall of the body portion 111; The packaging structure also includes a lead 19, one end of which is electrically connected to the first chip 13 and the other end of which is electrically connected to the platform portion 112.

[0045] For example, such as Figure 1As shown, the pin 11 includes a body portion 111 extending along the first direction D1 and a platform portion 112 perpendicularly connected to the inner sidewall of the body portion 111 and extending along the second direction D2. The first chip 13 includes a functional surface and a back surface opposite to the functional surface, and the first chip 13 is mounted on the front surface of the base island 10 with the back surface of the first chip 13 facing the base island 10 via an adhesive layer 14. The functional surface of the first chip 13 has multiple functional areas. One end of the lead 19 is electrically connected to the platform portion 112 in the pin 11, and the other end is electrically connected to a functional area in the functional surface of the first chip 13, so as to realize the transmission of electrical signals between the first chip 13 and the pin 11 through the lead 19.

[0046] This specific embodiment configures the pin 11 as including a body portion 111 extending along the first direction D1 and a platform portion 112 perpendicularly connected to the inner sidewall of the body portion 111 and extending along the second direction D2. On the one hand, this facilitates the electrical connection between the first chip 13 and the pin 11 via wire bonding, eliminating the need to adjust the connection process between the first chip 13 and the pin 11. On the other hand, the platform portion 112 provides lateral support to the columnar body portion 111, improving the overall stability of the pin 11 structure and preventing the body portion 111 from tilting or collapsing during subsequent chip mounting and molding processes.

[0047] In this specific embodiment, the platform portion 112 in the pin 11 is directly connected to the inner sidewall of the body portion 111, that is, the body portion 111 and the platform portion 112 in the same pin 11 are electrically connected. The first chip 13 is electrically connected to the platform portion 112 through the lead 19, and the second chip 15 is electrically connected to the body portion 111 through the solder ball 18. This allows control signals to be transmitted simultaneously to one of the functional areas of the second chip 15 and the first chip 13 through the same pin 11, without the need for other wiring structures. This simplifies the internal wiring layout of the package structure and reduces signal loss during transmission, thereby contributing to further improvement of the package structure performance.

[0048] In some embodiments, the width of the front side of the base island 10 is smaller than the width of the back side of the base island 10.

[0049] Specifically, since the pin 11 includes a body portion 111 extending along the first direction D1 and a platform portion 112 perpendicularly connected to the inner sidewall of the body portion 111 and extending along the second direction D2, that is, the platform portion 112 extends from the inner sidewall of the body portion 111 toward the base island 10. By setting the width of the front side of the base island 10 (e.g., the width of the front side of the base island 10 along the second direction D2) to be smaller than the width of the back side of the base island 10 (e.g., the width of the back side of the base island 10 along the second direction D2), on the one hand, by reducing the width of the front side of the base island 10, the distance between the front side of the base island 10 and the platform portion 112 can be increased, so that the base island 10 and the pin 11 can be sufficiently electrically isolated, avoiding signal crosstalk between the base island 10 and the pin 11; on the other hand, by increasing the width of the back side of the base island 10, the heat dissipation area of ​​the base island 10 can be increased, thereby further improving the heat dissipation performance of the package structure. In one example, the platform portion 112 includes a top surface and a bottom surface that are distributed opposite to each other. One end of the lead 19 is electrically connected to the first chip 13, and the other end is electrically connected to the top surface of the platform portion 112. The top surface of the platform portion 112 is flush with the front surface of the base island 10. On the one hand, this can reserve enough space for the process of mounting the first chip 13 and avoid affecting the mounting of the first chip 13. On the other hand, it facilitates the formation of the lead 19 that electrically connects the platform portion 112 and the first chip 13.

[0050] Figure 2 This is another structural schematic diagram of the encapsulation structure in a specific embodiment of the present invention. In some embodiments, the cross-section of the base island 10 is trapezoidal; or, The base island 10 includes a lower step 22 and an upper step 23 protruding from the lower step 22, wherein the width of the upper step 23 is smaller than the width of the lower step 22.

[0051] In one example, the base island 10 has a trapezoidal cross-section, and the width of the front side of the base island 10 is smaller than the width of the back side of the base island 10. The base island 10 has sloping sidewalls, such as... Figure 1 As shown. By setting the cross-section of the base island 10 to a trapezoidal shape, the distance between the front surface of the base island 10 and the platform portion 112 can be increased, and the base island 10 can be ensured to have sufficient stability to stably support the first chip 13 mounted on the front surface of the base island 10.

[0052] In another example, such as Figure 2As shown, the base island 10 has a stepped structure, meaning that the base island 10 includes a lower step 22 and an upper step 23 protruding from the lower step 22, and the lower step 22 protrudes from the upper step 23 in a direction parallel to the front of the base island 10 (e.g., the second direction D2). By setting the base island 10 as a stepped structure, the distance between the front of the base island 10 and the platform portion 112 can be increased, and there is no need to form an inclined base island sidewall through complex processes, thereby simplifying the manufacturing process of the base island 10 and improving the manufacturing efficiency of the lead frame.

[0053] In some embodiments, the lead frame further includes: The pre-encapsulation layer includes a filling portion 16 filled between the pin 11 and the base island 10 and an extension portion 17 connected to the outer side wall of the body portion 111, with the side of the second chip 15 located on the extension portion 17.

[0054] In some embodiments, the extension 17 includes an upper surface and a lower surface that are distributed opposite to each other, and the second chip 15 is located on the flat upper surface of the extension 17.

[0055] For example, the pre-encapsulation layer is formed by pre-encapsulating the base island 10 and the pin 11 to improve the overall mechanical strength of the lead frame. The pre-encapsulation layer includes a filler portion 16 filling the space between the pin 11 and the base island 10, and an extension portion 17 connected to the outer side wall of the body portion 111. In one example, the top surface of the filler portion 16, the top surface of the platform portion 112, and the front surface of the base island 10 are flush, and the top surface of the extension portion 17 is lower than the top surface of the platform portion 112. The pre-encapsulation layer is made of an insulating molding compound to electrically isolate the pin 11 from the base island 10 and prevent short circuits with the second chip 15. In one example, the pre-encapsulation layer is made of epoxy resin molding compound.

[0056] The extension 17 includes an upper surface and a lower surface that are distributed opposite to each other, and the upper surface of the extension 17 is a flat surface. When the second chip 15 is mounted onto the outer side wall of the body portion 111, the side of the second chip 15 can abut against the flat upper surface of the extension 17, so that the side of the second chip 15 contacts the upper surface of the extension 17. The extension 17 can support the second chip 15, improve the stability of the second chip 15, prevent the second chip 15 from falling off during the reflow soldering process, and ensure the accuracy and stability of the mounting position of the second chip 15.

[0057] In other embodiments, the extension 17 includes an upper surface and a lower surface that are oppositely distributed, and the extension 17 has a groove 21 recessed from the upper surface toward the interior of the extension 17, the second chip 15 being partially inserted into the groove 21.

[0058] For example, such as Figure 2 As shown, the extension 17 includes an upper surface and a lower surface that are distributed opposite to each other, and the extension 17 has a groove 21 recessed from the upper surface into the interior of the extension 17, and the groove 21 does not penetrate the extension 17. When mounting the second chip 15 onto the outer side wall of the body portion 111, a portion of the second chip 15 is inserted into the groove 21, such that the side surface of the second chip 15 contacts the bottom surface of the groove 21. On the one hand, the extension 17 can support the second chip 15, improving the stability of the second chip 15 and preventing the second chip 15 from falling off during the reflow soldering process; on the other hand, the groove 21 can also limit the position of the second chip 15, preventing the second chip 15 from shifting position.

[0059] In some embodiments, the back side of the second chip 15 abuts against the sidewall of the groove 21, thereby further improving the stability of the second chip 15.

[0060] In other embodiments, the width of the groove 21 is equal to or greater than the thickness of the second chip 15, and the side end of the second chip 15 is secured within the groove 21.

[0061] For example, by setting the width of the groove 21 to be equal to or greater than the thickness of the second chip 15, there is enough space in the groove 21 to accommodate the side end of the second chip 15, so that the side end of the second chip 15 can be fixed in the groove 21. This not only avoids the second chip 15 from rubbing against the groove 21, but also further improves the stability of the second chip 15 and further prevents the second chip 15 from shifting position.

[0062] In some embodiments, the packaging structure further includes: A molding layer 20 is located above the lead frame, and the molding layer 20 at least molds the first chip 13, the second chip 15 and the pin 11, and the top surface of the molding layer 20 is flush with the top surface of the pin 11.

[0063] For example, such as Figure 1 or Figure 2As shown, the packaging structure also includes a molding compound 20 located above the lead frame. The molding compound 20 continuously molds the first chip 13, the second chip 15, the pin 11, the lead 19, the conductive connecting post, and the solder ball 18. The top surface of the body portion 111 in the pin 11 is flush with the top surface of the molding compound 20 (i.e., the surface of the molding compound 20 facing away from the lead frame), thereby exposing the top surface of the body portion 111 from the top surface of the molding compound 20. The packaging structure can be electrically connected to other circuit components through the top surface of the body portion 111, facilitating the output of signals from the pin 11 from the top surface of the body portion 111 or the transmission of control signals to the pin 11 through the top surface of the body portion 111. Subsequently, the body portion 111 exposed from the molding compound 20 can also be mounted on a PCB board, allowing the exposed surface of the body portion 111 to dissipate heat upwards. Furthermore, a heat sink can be provided on the exposed body portion 111 to further improve the heat dissipation capacity of the lead frame.

[0064] In some embodiments, the material of the molding layer 20 is the same as the material of the pre-encapsulation layer.

[0065] Specifically, by using the same material for the molding compound 20 and the pre-encapsulation layer, the difference in thermal expansion coefficients between the molding compound 20 and the pre-encapsulation layer can be reduced, thereby enhancing the bonding force between them. This improves the overall stability of the encapsulation structure and also helps reduce internal stress. In one example, both the molding compound 20 and the pre-encapsulation layer are made of epoxy resin molding compound.

[0066] Figure 3 This is another structural schematic diagram of the packaging structure in a specific embodiment of the present invention. In other embodiments, the packaging structure further includes: The third chip 30 is mounted on the inner sidewall of the body 111, and the third chip 30 is electrically connected to the pin 11.

[0067] For example, such as Figure 3As shown, the first chip 13 includes a functional surface and a back surface opposite to the functional surface, and the first chip 13 is mounted on the front surface of the base island 10 with the back surface of the first chip 13 facing the base island 10 via the adhesive layer 14. The functional surface of the first chip 13 is electrically connected to the platform portion 112 in the pin 11 via the lead 19. The third chip 30 is flip-chip mounted on the inner sidewall of the body portion 111, and the body portion 111 and the third chip 30 are electrically connected via solder balls located between the body portion 111 and the third chip 30. The first chip 13 and the pin 11 are electrically connected via the lead 19, thereby eliminating the need to adjust the structure of the base island 10 and to perform a bonding process between the base island and the chip, which helps to reduce the difficulty of the packaging structure manufacturing process. In one example, by adjusting the position of the lead 19 and the position of the third chip 30, the lead 19 and the third chip 30 are isolated by the molding compound 20, avoiding short circuits between the lead 19 and the third chip 30.

[0068] In some embodiments, the second chip 15 and the third chip 30 are aligned; or... The second chip 15 is staggered from the third chip 30.

[0069] In one example, the functional surface of the first chip 13 is electrically connected to the platform portion 112 in the pin 11 via the lead 19. The second chip 15 and the third chip 30 are staggered to increase the distance between the third chip 30 and the lead 19, thereby avoiding signal crosstalk between the third chip 30 and the lead 19.

[0070] This specific embodiment also provides a method for forming an encapsulation structure. Figure 4 This is a flowchart illustrating the method for forming the encapsulation structure in a specific embodiment of the present invention. A schematic diagram of the encapsulation structure formed in this specific embodiment can be found in [reference needed]. Figures 1-3 .like Figures 1-4 As shown, the method for forming the packaging structure includes the following steps: Step S51, forming a lead frame, the lead frame including a base island 10 and pins 11 located outside the base island 10, the base island 10 including a front side and a back side opposite to each other, the pins 11 extending in a direction perpendicular to the front side of the base island 10; Step S52: The first chip 13 is attached to the front side of the base island 10, and the second chip 15 is attached to the side wall of the pin 11, and both the first chip 13 and the second chip 15 are electrically connected to the pin 11.

[0071] Figure 5This is a schematic diagram of a lead frame structure according to a specific embodiment of the present invention. In some embodiments, the specific steps for forming the lead frame include: Provide frame materials; The frame material is patterned to form an initial frame including the base island 10 and the pins 11 located outside the base island 10; The initial frame is pre-encapsulated to form a pre-encapsulation layer.

[0072] In some embodiments, the specific steps of patterning the frame material to form an initial frame including the base island 10 and the pins 11 located outside the base island 10 include: The frame material is patterned to form the base island 10 and the pins 11 including a body portion 111, the body portion 111 extending in a direction perpendicular to the front face 101 of the base island 10, the body portion 111 including an inner sidewall facing the base island 10 and an outer sidewall facing away from the base island 10.

[0073] For example, by patterning the frame material, an initial frame including the base island 10 and the pins 11 is formed. The pins 11 include a body portion 111 extending in a direction perpendicular to the front surface 101 of the base island 10, such as... Figure 5 As shown. The body portion 111 is positioned along a direction perpendicular to the front surface 101 of the base island 10 (e.g., Figure 5 The body portion 111 extends in the first direction D1), and the bottom surface of the body portion 111 is flush with the back surface 102 of the base island 10. The top surface of the body portion 111 is higher than the front surface 101 of the base island 10 to increase the area of ​​the sidewalls (including the inner sidewalls and the outer sidewalls) of the body portion 111. In one example, the body portion 111 is columnar. Along a direction parallel to the front surface 101 of the base island 10 (e.g., Figure 1 In the second direction (D2), the body portion 111 includes an inner sidewall facing the base island 10 and an outer sidewall facing away from the base island 10. The outer sidewall of the body portion 111 is a flat sidewall to facilitate stable subsequent mounting of the second chip 15 and to simplify the manufacturing process of the pins 11.

[0074] In some embodiments, the pin 11 further includes a platform portion 112, which protrudes from the inner sidewall of the body portion 111.

[0075] For example, by patterning the frame material, the pins 11 are formed, including the body portion 111 extending along the first direction D1 and the platform portion 112 perpendicularly connected to the inner sidewall of the body portion 111 and extending along the second direction D2. On the one hand, this facilitates the subsequent electrical connection between the first chip 13 and the pins 11 via wire bonding, without the need to adjust the connection process between the first chip 13 and the pins 11. On the other hand, the platform portion 112 provides lateral support to the columnar body portion 111, improving the overall stability of the pins 11 structure and preventing the body portion 111 from tilting or collapsing during subsequent chip mounting and molding processes.

[0076] In one example, the platform portion 112 includes a top surface and a bottom surface that are distributed opposite to each other. One end of the lead 19 is electrically connected to the first chip 13, and the other end is electrically connected to the top surface of the platform portion 112. The top surface of the platform portion 112 is flush with the front surface of the base island 10. On the one hand, this can reserve enough space for the process of mounting the first chip 13 and avoid affecting the mounting of the first chip 13. On the other hand, it facilitates the formation of the lead 19 that electrically connects the platform portion 112 and the first chip 13.

[0077] In some embodiments, the width of the front side 101 of the base island 10 is smaller than the width of the back side 102 of the base island 10.

[0078] For example, by patterning the frame material, the base island 10 is formed to be narrower at the top and wider at the bottom, so that the width of the front side 101 of the base island 10 is smaller than the width of the back side 102 of the base island 10. Since the pin 11 includes a body portion 111 extending along the first direction D1 and a platform portion 112 perpendicularly connected to the inner sidewall of the body portion 111 and extending along the second direction D2, the platform portion 112 extends from the inner sidewall of the body portion 111 towards the base island 10. By setting the width of the front side of the base island 10 (e.g., the width of the front side of the base island 10 along the second direction D2) to be smaller than the width of the back side of the base island 10 (e.g., the width of the back side of the base island 10 along the second direction D2), on the one hand, by reducing the width of the front side of the base island 10, the distance between the front side of the base island 10 and the platform portion 112 can be increased, so that the base island 10 and the pin 11 can be sufficiently electrically isolated, avoiding signal crosstalk between the base island 10 and the pin 11; on the other hand, by increasing the width of the back side of the base island 10, the heat dissipation area of ​​the base island 10 can be increased, thereby further improving the heat dissipation performance of the package structure. In one example, the top surface of the platform portion 112 is flush with the front side of the base island 10.

[0079] Figure 9 This is another structural schematic diagram of the lead frame in a specific embodiment of the present invention. In some embodiments, the cross-section of the base island 10 is trapezoidal; or, The base island 10 includes a lower step 22 and an upper step 23 protruding from the lower step 22, wherein the width of the upper step 23 is smaller than the width of the lower step 22.

[0080] In one example, the base island 10 has a trapezoidal cross-section, and the width of the front side of the base island 10 is smaller than the width of the back side of the base island 10. The base island 10 has sloping sidewalls, such as... Figure 5 As shown. By setting the cross-section of the base island 10 to a trapezoidal shape, the distance between the front surface of the base island 10 and the platform portion 112 can be increased, and the base island 10 can be ensured to have sufficient stability to stably support the first chip 13 mounted on the front surface of the base island 10.

[0081] In another example, such as Figure 9 As shown, the base island 10 has a stepped structure, that is, the base island 10 includes a lower step 22 and an upper step 23 protruding from the lower step 22, and the lower step 22 protrudes from the upper step 23 in a direction parallel to the front of the base island 10 (e.g., the second direction D2). By setting the base island 10 as a stepped structure, the distance between the front of the base island 10 and the platform portion 112 can be increased, and there is no need to form an inclined base island sidewall, thereby helping to simplify the manufacturing process of the base island 10 and improve the manufacturing efficiency of the base island 10.

[0082] In other embodiments, the initial frame of the base island 10 and the initial frame of the pin 11 are separate initial frames, and the initial frame including the base island 10 and the initial frame including the pin 11 are combined and fixed by the pre-encapsulation layer through a pre-encapsulation process.

[0083] For example, two independent initial frames can be pre-formed, one of which includes the base island 10 and the other includes the pin 11. Then, through a pre-encapsulation process, the initial frame including the base island 10 and the initial frame including the pin 11 are connected and fixed through the pre-encapsulation layer to form the lead frame including the base island 10 and the pin 11.

[0084] In some embodiments, the specific steps of mounting a first chip 13 onto the front side of the base island 10 and mounting a second chip 15 onto the sidewall of the pin 11, wherein both the first chip 13 and the second chip 15 are electrically connected to the pin 11, include: The first chip 13 is mounted on the front side of the base island 10 and electrically connected to the pin 11; The second chip 15 is mounted on the outer side wall of the body portion 111 and electrically connected to the pin 11.

[0085] Figure 6 This is a schematic diagram of the structure after the first chip is mounted on the lead frame in a specific embodiment of the present invention. Figure 10 This is another structural schematic diagram after the first chip is mounted on the lead frame in a specific embodiment of the present invention. In some embodiments, the specific steps of mounting the first chip 13 onto the front side of the base island 10 and electrically connecting the first chip 13 to the pin 11 include: The first chip 13 is mounted on the front side of the base island 10 with its functional surface facing away from the base island 10. A lead 19 is formed to electrically connect the first chip 13 to the platform portion 112 in the pin 11.

[0086] For example, the first chip 13 includes a functional surface and a back surface opposite to the functional surface, and the first chip 13 is mounted on the front surface of the base island 10 with the back surface of the first chip 13 facing the base island 10 via an adhesive layer 14. The functional surface of the first chip 13 has multiple functional areas, one end of the lead 19 is electrically connected to the platform portion 112 in the pin 11, and the other end is electrically connected to a functional area of ​​the functional surface of the first chip 13, such as... Figure 6 or Figure 10 As shown. In one example, there are multiple first chips 13, all of which are mounted on the front side of the base island 10 and are electrically connected to the pins 11. In this specific embodiment, "multiple" refers to two or more. In one example, the multiple first chips 13 have the same structure and function to further simplify the manufacturing process of the package structure. In another example, at least two of the first chips 13 have different structures or functions to further improve the integration of the package structure.

[0087] Figure 7This is a schematic diagram of the structure after mounting the second chip on the lead frame in a specific embodiment of the present invention. In some embodiments, the pre-encapsulation layer includes a filling portion 16 filling the space between the pin 11 and the base island 10, and an extension portion 17 connected to the outer sidewall of the body portion 111, the extension portion 17 including an upper surface and a lower surface that are distributed opposite to each other; the specific steps of mounting the second chip 15 to the outer sidewall of the body portion 111 and electrically connecting the second chip 15 to the pin 11 include: The second chip 15 is flipped onto the outer side wall of the body portion 111, such that the side of the second chip 15 is located on the flat upper surface of the extension portion 17.

[0088] For example, the second chip 15 includes a functional surface and a back surface that are relatively distributed. The second chip 15 is mounted on the outer side wall of the body portion 111 with its functional surface facing the body portion 111. In one example, the functional surface of the second chip 15 has conductive connection posts, which are connected to the outer side wall of the body portion 111 via solder balls 18. The conductive connection posts and solder balls 18 simultaneously establish an electrical connection between the second chip 15 and the body portion 111 containing the pins 11.

[0089] This specific embodiment increases the distance between the second chip 15 and the first chip 13 mounted on the front side of the base island 10 by flip-mounting the second chip 15 onto the outer sidewall of the body portion 111. This avoids signal crosstalk between the first chip 13 and the second chip 15, ensuring the performance stability of the package structure. Furthermore, it provides more space for wire bonding connections between the first chip 13 and the pins 11, further simplifying the manufacturing process of the package structure. Simultaneously, by flip-mounting the second chip 15 onto the outer sidewall of the body portion 111, the second chip 15 is positioned vertically with its sidewall facing the lead frame, reducing the area occupied by the second chip 15 on the lead frame. Moreover, it eliminates the need for wire bonding to electrically connect the second chip 15 to the pins 11, further improving the performance of the package structure, simplifying the manufacturing process, and increasing manufacturing efficiency.

[0090] In this specific embodiment, the platform portion 112 in the pin 11 is directly connected to the inner sidewall of the body portion 111, that is, the body portion 111 and the platform portion 112 in the same pin 11 are electrically connected. The first chip 13 is electrically connected to the platform portion 112 through the lead 19, and the second chip 15 is electrically connected to the body portion 111 through the solder ball 18. This allows control signals to be transmitted simultaneously to one of the functional areas of the second chip 15 and the first chip 13 through the same pin 11, without the need for other wiring structures. This simplifies the internal wiring layout of the package structure and reduces signal loss during transmission, thereby contributing to further improvement of the package structure performance.

[0091] The pre-encapsulation layer is formed by pre-encapsulating the base island 10 and the pin 11. The pre-encapsulation layer includes a filling portion 16 filling the space between the pin 11 and the base island 10, and an extension portion 17 connected to the outer sidewall of the body portion 111. In one example, the top surface of the filling portion 16, the top surface of the platform portion 112, and the front surface of the base island 10 are flush, and the top surface of the extension portion 17 is lower than the top surface of the platform portion 112. The pre-encapsulation layer is made of an insulating molding compound to electrically isolate the pin 11 from the base island 10 and prevent short circuits with the second chip 15. In one example, the pre-encapsulation layer is made of epoxy resin molding compound.

[0092] The extension 17 includes an upper surface and a lower surface that are oppositely distributed, and the upper surface of the extension 17 is a flat surface. When the second chip 15 is mounted onto the outer sidewall of the body portion 111, the second chip 15 can be made to abut against the flat upper surface of the extension 17, such that the side surface of the second chip 15 contacts the upper surface of the extension 17. Figure 7 As shown, the extension 17 can support the second chip 15, improving the stability of the second chip 15 and preventing it from falling off during the reflow soldering process. Figure 11 This is another structural schematic diagram after the second chip is mounted on the lead frame in a specific embodiment of the present invention. In some other embodiments, the pre-encapsulation layer includes a filling portion 16 filling the space between the pin 11 and the base island 10, and an extension portion 17 connected to the outer sidewall of the body portion 111. The extension portion 17 includes an upper surface and a lower surface that are oppositely distributed, and the extension portion 17 has a groove 21 recessed from the upper surface into the interior of the extension portion 17. See [link to previous section]. Figure 9 and Figure 10The specific steps of mounting the second chip 15 onto the outer sidewall of the body portion 111 and electrically connecting the second chip 15 to the pin 11 include: The second chip 15 is flipped onto the outer side wall of the body portion 111, such that the second chip 15 is partially inserted into the groove 21, as shown. Figure 11 As shown.

[0093] For example, such as Figure 9 and Figure 10 As shown, the extension 17 includes an upper surface and a lower surface that are distributed opposite to each other, and the extension 17 has a groove 21 recessed from the upper surface into the interior of the extension 17. When mounting the second chip 15 onto the outer side wall of the body portion 111, a portion of the second chip 15 is inserted into the groove 21, such that the side surface of the second chip 15 contacts the bottom surface of the groove 21. On the one hand, the extension 17 can support the second chip 15, improving the stability of the second chip 15 and preventing the second chip 15 from falling off during the reflow soldering process; on the other hand, the groove 21 can also define the position of the second chip 15, preventing the second chip 15 from shifting position.

[0094] In some embodiments, after mounting the first chip 13 onto the front side of the base island 10 and mounting the second chip 15 onto the sidewall of the pin 11, the following steps are further included: A third chip 30 is mounted on the inner sidewall of the body portion 111, and the third chip 30 is electrically connected to the pin 11.

[0095] In some embodiments, the specific steps of mounting the third chip 30 onto the inner sidewall of the body portion 111 and electrically connecting the third chip 30 to the pin 11 include: The third chip 30 is flip-mounted onto the inner wall of the body portion 111 above the platform portion 112, see [reference]. Figure 3 .

[0096] In one example, such as Figure 3As shown, the first chip 13 includes a functional surface and a back surface opposite to the functional surface, and the first chip 13 is mounted on the front surface of the base island 10 with the back surface of the first chip 13 facing the base island 10 via the adhesive layer 14. The functional surface of the first chip 13 is electrically connected to the platform portion 112 in the pin 11 via the lead 19. The third chip 30 is flip-chip mounted on the inner sidewall of the body portion 111, and the body portion 111 and the third chip 30 are electrically connected via solder balls located between the body portion 111 and the third chip 30. The first chip 13 and the pin 11 are electrically connected via the lead 19, thereby eliminating the need to adjust the structure of the base island 10 and to perform a bonding process between the base island and the chip, which helps to reduce the difficulty of the packaging structure manufacturing process. In one example, by adjusting the position of the lead 19 and the position of the third chip 30, the lead 19 and the third chip 30 are isolated by the molding compound 20, avoiding short circuits between the lead 19 and the third chip 30.

[0097] In some embodiments, the second chip 15 and the third chip 30 are aligned; or... The second chip 15 is staggered from the third chip 30.

[0098] In one example, the functional surface of the first chip 13 is electrically connected to the platform portion 112 in the pin 11 via the lead 19. The second chip 15 and the third chip 30 are staggered to increase the distance between the third chip 30 and the lead 19, thereby avoiding signal crosstalk between the third chip 30 and the lead 19.

[0099] Figure 8 This is a schematic diagram of the structure after the molding layer is formed in a specific embodiment of the present invention. Figure 12 This is another structural diagram after the molding compound layer is formed in a specific embodiment of the present invention. In some embodiments, after mounting the first chip 13 onto the front side of the base island 10 and mounting the second chip 15 onto the sidewall of the pin 11, the following steps are further included: A molding layer 20 is formed to encapsulate the first chip 13, the second chip 15, and the pins 11, as follows: Figure 8 and Figure 12 As shown.

[0100] In some embodiments, after forming the molding layer 20 that encapsulates the first chip 13, the second chip 15, and the pins 11, the following steps are further included: The molding layer 20 is planarized so that the top surface of the molding layer 20 is flush with the top surface of the pin 11.

[0101] For example, after mounting the first chip 13 and the second chip 15 (or mounting the first chip 13, the second chip 15, and the third chip 30), a molding layer 20 is formed by molding process to mold the first chip 13, the second chip 15, and the pins 11 (or to mold the first chip 13, the second chip 15, the third chip 30, and the pins 11). See [link to documentation]. Figure 8 or Figure 12 Subsequently, the molding compound 20 is subjected to planarization treatment such as chemical mechanical polishing, so that the top surface of the molding compound 20 is flush with the top surface of the pin 11, that is, the top surface of the remaining molding compound 20 after polishing is flush with the top surface of the body portion 111 in the pin 11.

[0102] The top surface of the body portion 111 in pin 11 is flush with the top surface of the molding compound 20 (i.e., the surface of the molding compound 20 facing away from the lead frame), thereby exposing the top surface of the body portion 111 from the top surface of the molding compound 20. The package structure can be electrically connected to other circuit components through the top surface of the body portion 111, facilitating the routing of signals from pin 11 from the top surface of the body portion 111 or the transmission of control signals to pin 11 through the top surface of the body portion 111. Subsequently, the top surface of the body portion 111 can be used to mount it onto a PCB board, allowing the exposed surface of the body portion 111 to dissipate heat upwards. Furthermore, a heat sink can be installed on the exposed body portion 111 to further improve its heat dissipation capacity.

[0103] In some embodiments, the material of the molding layer 20 is the same as the material of the pre-encapsulation layer.

[0104] Specifically, by using the same material for the molding compound 20 and the pre-encapsulation layer, the difference in thermal expansion coefficients between the molding compound 20 and the pre-encapsulation layer can be reduced, thereby enhancing the bonding force between them. This improves the overall stability of the encapsulation structure and also helps reduce internal stress. In one example, both the molding compound 20 and the pre-encapsulation layer are made of epoxy resin molding compound.

[0105] The packaging structure and its formation method provided in this specific embodiment, by setting the pins in the lead frame to extend in a direction perpendicular to the front surface of the base island (e.g., the front surface of the base island is horizontal, and the pins extend vertically), allows a first chip to be mounted on the front surface of the base island and a second chip to be mounted on the sidewall extending vertically from the pins. This enables a larger number of chips to be mounted within the limited space of the packaging structure, increasing the integration density. Simultaneously, because the pins extend in a direction perpendicular to the front surface of the base island, the base island and the pins are in different planes, allowing the base island and the pins to dissipate heat from different surfaces. For example, the base island can dissipate heat from the top and bottom, while the pins can dissipate heat from the side, significantly improving the heat dissipation performance of the packaging structure while increasing its integration density.

[0106] 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.

[0107] 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 use of data can be interchanged where appropriate. The term "one or more" depends at least in part on the context and can be used to describe features, structures, or characteristics in a singular sense, or in a plural sense to describe combinations of features, structures, or characteristics. The term "based on" can be understood as not necessarily intended to express an exclusive set of factors, but can instead, also at least in part on the context, allow for the presence of other factors that are not necessarily explicitly described. Furthermore, embodiments and features in embodiments of this invention can be combined with each other without conflict. 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 / identical parts between embodiments can be referred to mutually.

[0108] 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 packaging structure, characterized in that, include: A lead frame includes a base island and pins located outside the base island, the base island including a front and a back side oppositely distributed, the pins extending in a direction perpendicular to the front side of the base island; The first chip is mounted on the front side of the base island, and the first chip is electrically connected to the pins; The second chip is mounted on the sidewall of the pin and is electrically connected to the pin.

2. The packaging structure according to claim 1, characterized in that, The pin includes a body portion that extends in a direction perpendicular to the front of the base island, and the body portion includes an inner sidewall facing the base island and an outer sidewall facing away from the base island. The second chip is flip-mounted onto the outer side wall of the main body.

3. The packaging structure according to claim 2, characterized in that, The pin also includes a platform portion, which protrudes from the inner sidewall of the body portion; The packaging structure also includes leads, one end of which is electrically connected to the first chip and the other end of which is electrically connected to the platform section.

4. The packaging structure according to claim 2, characterized in that, The width of the front side of the base island is smaller than the width of the back side of the base island.

5. The packaging structure according to claim 4, characterized in that, The cross-section of the base island is trapezoidal; or, The base island includes a lower step and an upper step protruding from the lower step, wherein the width of the upper step is smaller than the width of the lower step.

6. The packaging structure according to claim 2, characterized in that, The lead frame also includes: The pre-encapsulation layer includes a filler portion filling between the pin and the base island, and an extension connected to the outer sidewall of the body portion, wherein the side of the second chip is located on the extension.

7. The packaging structure according to claim 6, characterized in that, The extension includes an upper surface and a lower surface that are relatively distributed, and the second chip is located on the flat upper surface of the extension.

8. The packaging structure according to claim 6, characterized in that, The extension includes an upper surface and a lower surface that are oppositely distributed, and the extension has a groove recessed from the upper surface into the interior of the extension, the second chip portion being inserted into the groove.

9. The packaging structure according to claim 8, characterized in that, The back of the second chip rests against the sidewall of the groove.

10. The packaging structure according to claim 8, characterized in that, The width of the groove is equal to or greater than the thickness of the second chip, and the side end of the second chip is secured within the groove.

11. The packaging structure according to claim 6, characterized in that, Also includes: A molding compound is located above the lead frame, and the molding compound at least molds the first chip, the second chip, and the pins, and the top surface of the molding compound is flush with the top surface of the pins.

12. The packaging structure according to claim 11, characterized in that, The material of the molding layer is the same as the material of the pre-encapsulation layer.

13. The packaging structure according to claim 3, characterized in that, Also includes: The third chip is mounted on the inner sidewall of the main body, and the third chip is electrically connected to the pin.

14. The packaging structure according to claim 13, characterized in that, The second chip is aligned with the third chip; or, The second chip and the third chip are staggered.

15. A method for forming an encapsulation structure, characterized in that, Includes the following steps: A lead frame is formed, the lead frame including a base island and pins located outside the base island, the base island including a front side and a back side opposite to each other, and the pins extending in a direction perpendicular to the front side of the base island; A first chip is mounted on the front side of the base island, and a second chip is mounted on the side wall of the pin, with both the first chip and the second chip being electrically connected to the pin.

16. The method for forming the packaging structure according to claim 15, characterized in that, The specific steps for forming the lead frame include: Provide frame materials; The frame material is patterned to form an initial frame including the base island and the pins located outside the base island; The initial frame is pre-encapsulated to form a pre-encapsulation layer.

17. The method for forming the packaging structure according to claim 16, characterized in that, The specific steps of patterning the frame material to form an initial frame including the base island and the pins located outside the base island include: The frame material is patterned to form the base island and the pins including a body portion extending in a direction perpendicular to the front of the base island, the body portion including an inner sidewall facing the base island and an outer sidewall facing away from the base island.

18. The method for forming the packaging structure according to claim 17, characterized in that, The pin also includes a platform portion that protrudes from the inner sidewall of the body portion.

19. The method for forming the packaging structure according to claim 18, characterized in that, The width of the front side of the base island is smaller than the width of the back side of the base island.

20. The method for forming the packaging structure according to claim 19, characterized in that, The cross-section of the base island is trapezoidal; or, The base island includes a lower step and an upper step protruding from the lower step, wherein the width of the upper step is smaller than the width of the lower step.

21. The method for forming the packaging structure according to claim 18, characterized in that, The specific steps of mounting a first chip onto the front side of the base island and mounting a second chip onto the sidewall of the pin, wherein both the first chip and the second chip are electrically connected to the pin, include: The first chip is mounted on the front side of the base island, and the first chip is electrically connected to the pins; The second chip is mounted on the outer side wall of the body and electrically connected to the pin.

22. The method for forming the packaging structure according to claim 21, characterized in that, The specific steps of mounting the first chip onto the front side of the base island and electrically connecting the first chip to the pins include: The first chip is mounted on the front side of the base island with its functional surface facing away from the base island. A lead is formed to electrically connect the first chip to the platform portion of the pin.

23. The method for forming the packaging structure according to claim 21, characterized in that, The pre-encapsulation layer includes a filling portion between the pin and the base island and an extension portion connected to the outer sidewall of the body portion, the extension portion including an upper surface and a lower surface that are distributed opposite to each other; The specific steps of mounting the second chip onto the outer wall of the body and electrically connecting the second chip to the pins include: The second chip is flipped onto the outer side wall of the body portion, such that the side of the second chip is located on the flat upper surface of the extension portion.

24. The method for forming the packaging structure according to claim 21, characterized in that, The pre-encapsulation layer includes a filling portion between the pin and the base island and an extension portion connected to the outer sidewall of the body portion. The extension portion includes an upper surface and a lower surface that are distributed opposite to each other, and the extension portion has a groove recessed from the upper surface into the interior of the extension portion. The specific steps of mounting the second chip onto the outer wall of the body and electrically connecting the second chip to the pins include: The second chip is flipped onto the outer wall of the body portion, such that the second chip portion is inserted into the groove.

25. The method for forming the packaging structure according to claim 21, characterized in that, After mounting the first chip onto the front side of the base island and mounting the second chip onto the sidewall of the pin, the following steps are also included: A third chip is mounted on the inner wall of the main body, and the third chip is electrically connected to the pin.

26. The method for forming the packaging structure according to claim 15, characterized in that, After mounting the first chip onto the front side of the base island and mounting the second chip onto the sidewall of the pin, the following steps are also included: A molding layer is formed to encapsulate the first chip, the second chip, and the pins.

27. The method for forming the packaging structure according to claim 26, characterized in that, After forming the molding layer that encapsulates the first chip, the second chip, and the pins, the method further includes the following step: planarizing the molding layer so that the top surface of the molding layer is flush with the top surface of the pins.

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