Preparation method of packaging structure
By forming a cutting groove and coating a protective material layer during the packaging structure fabrication process, combined with the method of electroplating a tin-climbing layer, the problem of metal burr bridging was solved, thereby improving the stability and electrical reliability of the packaging structure.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHANGJIANG ELECTRONICS TECH CHUZHOU
- Filing Date
- 2025-12-26
- Publication Date
- 2026-04-28
AI Technical Summary
In the fabrication of quad flat leadless package structures, existing technologies are prone to metal burrs bridging, leading to electrical failures and affecting product yield. Furthermore, the micro-etching process can easily corrode the pins, making it difficult to ensure soldering reliability.
The process involves first forming a dicing groove and coating it with a protective material layer, then forming an electroplated tin layer on the sidewalls of the dicing groove and the uncovered areas. This two-stage dicing process creates a discrete package structure, avoiding burr bridging and replacing the micro-etching process.
It effectively prevents burr bridging, maintains pin integrity, improves product stability and yield, and ensures electrical performance and welding reliability.
Smart Images
Figure CN121941384A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of semiconductor packaging technology, and in particular to a method for preparing a packaging structure. Background Technology
[0002] Automotive electronics is a crucial foundation of the automotive industry. To ensure compliance with current automotive requirements for safety and high reliability, the automotive industry requires original equipment manufacturers to conduct automated visual inspections after all components are assembled. For quad flat leadless packages, it is not easy to see solderable or exposed pins, making it impossible to confirm whether they have been successfully soldered onto the printed circuit board. The edges of the package have copper plating on exposed pins or terminals, which is easily oxidized, making it difficult to wet the sidewall solder.
[0003] Currently, the industry often adds a cutting process before electroplating to achieve tin plating on the sides of the pins. After cutting, metal burrs are easily generated, and burr bridging can easily occur between the pins. In related technologies, a micro-etching process is required after cutting to reduce metal burrs. However, micro-etching can easily corrode the pins, leading to pin failure, affecting the electrical properties of the product, and reducing the yield. Summary of the Invention
[0004] The purpose of this application is to provide a method for fabricating a packaging structure that prevents burr bridging between metal burrs, replaces micro-etching, maintains pin integrity, improves product stability, and increases yield.
[0005] To achieve the above objectives, this application first provides a method for preparing a packaging structure, comprising the following steps: A lead frame is provided, which is composed of several frame units, each frame unit including a base island and a pin, and the frame units are connected by a connecting rib structure. Chip mounting, wherein a plurality of the chips are bonded to the first surface of a plurality of the base islands; A molding compound is formed, which encapsulates the lead frame and the chip. A first cut is made at the corresponding position of the cutting channel between the frame units to form a cutting groove. The depth of the cutting groove is less than the thickness of the lead frame, and the width of the cutting groove is greater than the width of the final cutting channel. A protective material layer is applied to the bottom of the cutting groove to form a protective layer; An electroplated tin layer is formed at the corresponding pin positions on the side wall surface of the cutting groove and the bottom surface of the cutting groove that is not covered by the protective material layer; A second cut is made along the cutting lines between the frame units to form a discrete encapsulation structure.
[0006] In some embodiments of this application, the lead frame further includes: The aforementioned base islands are arranged in rows and columns; Several of the aforementioned pins are arranged sequentially at intervals along the circumference of the base island; The pins of adjacent frame units are connected by the connecting rib structure to form the lead frame.
[0007] In some embodiments of this application, a number of the pins are disposed on both sides of the base island or a number of the pins are disposed around the base island.
[0008] In some embodiments of this application, the frame unit includes at least one of the base islands and a plurality of the pins.
[0009] In some embodiments of this application, the mounted chip specifically includes: The second surface of the chip is bonded to the first surface of the base island; The first surface of the chip is connected to the first surface of the pin via a metal lead.
[0010] In some embodiments of this application, the specific process of forming the cutting groove by the first cutting includes: A punching process is used to remove the plastic sealing material and part of the connecting rib structure in the thickness direction from the second surface of the connecting rib structure to form a cutting groove.
[0011] In some embodiments of this application, the electroplated tin layer comprises one or more layers.
[0012] In some embodiments of this application, the specific processes for forming discrete packaging structures include: A second cut is made along the cutting grooves between the frame units to completely remove the protective material layer coated at the bottom of the cutting grooves, forming several discrete encapsulation structures.
[0013] In some embodiments of this application, the protective material layer specifically includes printing ink and green paint.
[0014] In some embodiments of this application, the process for forming the protective material layer includes one of screen printing, inkjet printing, and slot coating.
[0015] In some embodiments of this application, the connecting reinforcement structure includes a central reinforcement and connecting support reinforcements for connecting pipe feet, and the protective material layer completely covers the surface of the central reinforcement.
[0016] In some embodiments of this application, the width of the protective material layer at the bottom of the cutting groove is smaller than the width of the cutting channel but larger than the width of the central rib.
[0017] In some embodiments of this application, the protective material layer has a certain distance from the pin.
[0018] The beneficial effects of this application are: The method for preparing the packaging structure of this application includes the following steps: A leadframe is provided, comprising a plurality of frame units, each frame unit including a base island and pins, the frame units being connected by a connecting rib structure; a plurality of chips are mounted, wherein a plurality of chips are bonded to the first surfaces of a plurality of base islands; a molding compound is formed, the molding compound encapsulating the leadframe and the chips; a first cut is made at corresponding positions of the dicing track between the frame units to form a dicing groove, the depth of the dicing groove being less than the thickness of the leadframe, and the width of the dicing groove being greater than the width of the final dicing track; a protective material layer is coated at the bottom of the dicing groove to form a protective material layer; an electroplated tin layer is formed at the pin positions corresponding to the sidewall surface of the dicing groove and the bottom surface of the dicing groove not covered by the protective material layer; a second cut is made along the dicing track between the frame units to form a discrete package structure.
[0019] In this application, the preparation method follows a linear process of sequentially providing a frame, mounting chips, forming a molding compound, making a first cut, applying a protective material layer, forming an electroplated tin layer, and making a second cut. This ensures that the components are processed in an orderly manner and do not interfere with each other. By partially applying the protective material layer, the electroplated tin layer is generated only at the pin positions corresponding to the side wall surface of the cutting groove and the bottom surface of the cutting groove not covered by the protective material layer, eliminating burr bridging and ensuring electrical performance. Attached Figure Description
[0020] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In addition, in the following drawings, the components are not necessarily drawn to scale, and components with similar related characteristics or features may have the same or similar reference numerals.
[0021] Figure 1 This is a schematic flowchart illustrating the fabrication method of the packaging structure provided in some embodiments of this application; Figures 2-9 This is a schematic diagram of the encapsulation structure formation process provided in some embodiments of this application; Figure 10 This is a schematic diagram of the lead frame structure provided in some embodiments of this application; Figure 11 This is a schematic diagram of the lead frame structure provided in some embodiments of this application; Figure 12This is a schematic diagram of the lead frame structure provided in some embodiments of this application. Detailed Implementation
[0022] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be more thorough and complete.
[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.
[0024] In the description of this application, it should be noted that the use of terms such as "first" and "second" to define objects (such as elements, components, regions, layers, doping types and / or parts) is merely for the purpose of distinguishing different objects and is not necessarily used to describe a specific order or sequence. Unless the context clearly indicates otherwise, it should be understood that such data can be used interchangeably where appropriate.
[0025] In the description of this application, it should be understood that the singular forms “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that when the terms “compose” and / or “comprise” are used in this specification, the presence of the stated feature, integer, step, operation, element, and / or part is established, but the presence or addition of one or more other features, integers, steps, operations, elements, parts, and / or groups is not excluded. Meanwhile, when used herein, the term “and / or” includes any and all combinations of the associated listed items.
[0026] In the description of this application, it should also be noted that when a component is referred to as "on another component," "connected to another component," or "in contact with another component," it can mean not only that a component is directly on, directly connected to, or directly in contact with another component, but also that an intermediate component can be inserted between the two components. Furthermore, "connection" includes not only fixed connections but also detachable connections or integral connections. Similarly, when an element is referred to as "electrically connected," "electrically contacted," "electrically coupled," or "electrically coupled to" another element, the two elements can be in direct electrical contact or point coupling, or they can be in electrical contact or point coupling through an intermediate component.
[0027] In the description of this application, it should also be noted that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is usually based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this application and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this application; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.
[0028] Furthermore, in the description of this application, spatial relation terms such as "below," "under," "below," "below," "below," "above," "on the upper surface of," "above," etc., can be used to describe the spatial positional relationship between one element or feature shown in the figures and other elements or features. It should be understood that spatial relation terms, in addition to the orientation shown in the figures, also include different orientations of elements or features in use and operation. For example, if an element or feature in the figures is flipped or inverted, an element or feature described as "below" or "below" other elements or features will be oriented "above" other elements or features. Furthermore, elements may also include other orientations (e.g., rotated by an angle or other orientations).
[0029] This application provides a method for preparing a packaging structure. Figure 1 This is a schematic flowchart illustrating the preparation method of the packaging structure provided in some embodiments of this application.
[0030] refer to Figure 1 The method for preparing the encapsulation structure includes the following steps: Step S101: Provide a lead frame 1, which is composed of several frame units, each frame unit including a base island and a pin, and the frame units are connected by a connecting rib structure. Step S102, chip mounting, wherein a plurality of the chips are bonded to the first surface of a plurality of the base islands; Step S103: Form a molding compound layer, which encapsulates the lead frame and the chip; Step S104: A first cut is made at the corresponding position of the cutting channel between the frame units to form a cutting groove. The depth of the cutting groove is less than the thickness of the lead frame, and the width of the cutting groove is greater than the width of the final cutting channel. Step S105: A protective material layer is formed by coating the bottom of the cutting groove; Step S106: An electroplated tin layer is formed at the corresponding pin positions on the side wall surface of the cutting groove and the bottom surface of the cutting groove not covered by the protective material layer. Step S107: Make a second cut along the cutting lines between the frame units to form a discrete encapsulation structure.
[0031] The fabrication method of the encapsulation structure is described in detail below with reference to the accompanying drawings.
[0032] First, refer to Figure 1 and Figure 2 In step S101, a lead frame 1 is provided. The lead frame 1 is composed of several frame units. Each frame unit includes a base island 11 and a pin 12. The frame units are connected by a connecting rib structure 13.
[0033] The lead frame 1 serves as the basic support structure of the packaging structure, providing mechanical support and electrical connection for each component. The frame units are connected by the connecting rib structure 13 to ensure overall stability during processing. The connecting rib structure 13 facilitates subsequent cutting and separation, and prevents early deformation.
[0034] In some embodiments of this application, the lead frame 1 further includes: Several of the aforementioned base islands 11 are arranged in rows and columns; A plurality of the pins 12 are arranged sequentially at intervals along the circumference of the base island 11; The pins 12 of adjacent frame units are connected by the connecting rib structure 13 to form the lead frame 1.
[0035] Specifically, the arrangement of several base islands 11 in rows and columns makes the lead frame 1 suitable for high-speed automated production, reducing adjustment time; the circumferential arrangement of several pins 12 ensures that the performance of each package structure is uniform, improving production efficiency and ensuring the consistency of the shape of the pins 12.
[0036] In some embodiments of this application, the frame unit includes one base island 11 and a plurality of pins 12.
[0037] In other embodiments of this application, the frame unit includes a plurality of base islands 11 and a plurality of pins 12, and different chips can be disposed on different base island surfaces.
[0038] In some embodiments of this application, a number of the pins 12 are disposed on both sides of the base island 11 or a number of the pins 12 are disposed around the base island 11.
[0039] In some embodiments of this application, the connecting reinforcement structure 13 includes a central reinforcement 14 and connecting support reinforcement 15 for connecting tube feet 12. The tube feet 12 of adjacent frame units are connected by connecting support reinforcement 15 and central reinforcement 14 to form the lead frame 1. The connecting reinforcement structure 13 is a solid connecting reinforcement structure or a semi-solid connecting reinforcement structure.
[0040] Specifically, the connecting rib structure 13 includes a central rib 14 and a connecting support rib 15. The connecting support rib 15 is connected to the tube foot 12. The protective material layer 5 completely covers the surface of the central rib 14 to achieve local shielding, insulate the central rib 14, and prevent the probability of metal burrs 42 generated by secondary cutting bridging the tube foot 12.
[0041] In some embodiments of this application, the protective material layer 5 and the pin 12 have a certain distance between them.
[0042] Next, refer to Figures 2 to 4 In step S102, the chips 2 are mounted, and a plurality of the chips 2 are bonded to the first surfaces of a plurality of the base islands 11.
[0043] The chip 2 is mounted on the first surface of the base island 11. The chip 2 is heat-dissipated and electrically connected through the base island 11 to ensure the stability of the chip 2's performance.
[0044] In some embodiments of this application, the second surface of the chip 2 is bonded to the first surface of the base island 11; the first surface of the chip 2 is connected to the first surface of the pin 12 via metal leads 21. The metal leads 21 are formed using a wire bonding process.
[0045] In some other embodiments of this application, when the chip 2 is a flip chip, the second surface of the chip 2 is bonded to the first surface of the base island 11, and the pins of the second surface of the chip 2 are directly electrically connected to the first surface of the pin 12.
[0046] In some embodiments of this application, the chip 2 may include a logic chip or a memory chip. In some embodiments, the logic chip may include a gate array, a cell substrate array, an embedded array, a structured application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a complex programmable logic device (CPLD), a central processing unit (CPU), a microprocessor unit (MPU), a microcontroller unit (MCU), a logic integrated circuit (IC), an application processor (AP), a display driver IC (DDI), a radio frequency (RF) chip, a power supply chip, or a complementary metal-oxide-semiconductor (CMOS) image sensor.
[0047] In some embodiments, the memory chip may include volatile memory chips (such as dynamic random access memory (DRAM) or static RAM (SRAM) or non-volatile memory chips (such as flash memory, phase-change RAM (PRAM), magnetoresistive RAM (MRAM), ferroelectric RAM (FeRAM), or resistive RAM (ReRAM)). In a specific embodiment, the memory chip may include high-bandwidth memory (HBM) containing DRAM chips.
[0048] Next, refer to Figure 5 Step S103 is performed to form a molding layer 3, which encapsulates the lead frame 1 and the chip 2.
[0049] The molding layer 3 encapsulates the lead frame 1 and the chip 2, providing physical protection and insulation to prevent damage to the internal structure from the external environment and improve packaging reliability.
[0050] In some embodiments of this application, the material of the molding layer 3 may be a filler-containing epoxy resin, polyimide resin, benzocyclobutene resin, or polybenzoxazole resin; or it may be a filler-containing polybutylene terephthalate, polycarbonate, polyethylene terephthalate, polyethylene, polypropylene, polyolefin, polyurethane, polyolefin, polyethersulfone, polyamide, polyimide, ethylene-vinyl acetate copolymer, or polyvinyl alcohol. In some embodiments, the filler may be an inorganic filler or an organic filler.
[0051] In some embodiments of this application, the process of forming the encapsulation layer 3 includes compression molding or transfer molding.
[0052] Next, refer to Figures 2 to 9 In step S104, a first cut is made at the corresponding position of the cutting channel 4 between the frame units to form the cutting groove 41. The depth of the cutting groove 41 is less than the thickness of the lead frame 1, and the width of the cutting groove 41 is greater than the width of the final cutting channel 4.
[0053] By performing a first cut, a pre-cut groove 41 is formed at the position of the cut channel 4 between the frame units to remove some material. During the first cut, the depth of the cut groove 41 is limited to be less than the thickness of the lead frame 1, and the width of the cut groove 41 is greater than the width of the final cut channel 4, so that a wettable side wing package can be formed on the side of the package structure.
[0054] The first cut is made using a cutting tool. However, when the cutting tool is used, the connecting rib structure 13 at the bottom of the cutting groove 41 will be cut, which will produce metal burrs 42. Since the subsequent formation of the electroplated tin layer will further form a metal layer on the surface of the metal burrs 42, the metal layer corresponding to the metal burrs 42 will exceed the width of the cutting channel 4 during the second cut, resulting in the final bridging of adjacent pins 12 and affecting electrical performance.
[0055] In some embodiments of this application, the specific process of forming the cutting groove 41 by the first cutting includes: The plastic sealant and part of the thickness of the connecting rib structure 13 on the second surface of the connecting rib structure 13 are removed by a cutting tool to form a cutting groove 41.
[0056] Next, refer to Figure 8 In conjunction with references Figures 10 to 12 In step S105, a protective material layer 5 is formed by coating the bottom of the cutting groove 41.
[0057] The protective material layer 5 is applied to the bottom of the cutting groove 41 to cover the connecting rib structure 13 and potential metal burrs 42, to insulate and prevent metal from being deposited on the metal burrs 42 during subsequent electroplating, and to avoid the risk of bridging between the pins 12.
[0058] In existing technologies, the metal layer formed by the metal burrs 42 during the first cut often exceeds the width of the sprue 4 during the second cut, leading to bridging between adjacent pins 12 and affecting electrical performance. Even if the metal layer formed by the metal burrs 42 during the sprue plating process does not exceed the width of the sprue 4 during the second cut, because the metal layer formed by the metal burrs 42 during the sprue plating process is relatively close to the edge of the sprue 4, some of the metal layer may be squeezed into the sidewalls between adjacent pins 12 of the discrete package structure during the second cut, causing bridging between adjacent pins 12 and affecting the electrical performance of the package structure. Therefore, in this application, the protective material layer 5 completely covers the central rib 14 area at the bottom of the cutting groove 41, completely covering the metal burrs 42 generated in the central rib 14 area. No additional metal layer is formed at the bottom of the cutting groove 41 during the sprue plating process. Since there is no additional metal layer at the bottom of the cutting groove 41 during the second cut, the risk of bridging between the pins 12 can be better avoided.
[0059] In some embodiments of this application, the width of the protective material layer 5 at the bottom of the cutting groove 41 is smaller than the width of the cutting channel 4 but larger than the width of the central rib 14.
[0060] The protective material layer 5 is made of a non-metallic material and does not affect subsequent secondary cutting.
[0061] In some embodiments of this application, the protective material layer 5 specifically includes printing ink, green paint, etc.
[0062] In some embodiments of this application, the process for forming the protective material layer 5 includes one of screen printing, inkjet printing, and slot coating.
[0063] Next, refer to Figures 8 to 12 In step S106, an electroplated tin layer 6 is formed at the pin 12 positions on the side wall surface of the cutting groove 41 and the bottom surface of the cutting groove 41 not covered by the protective material layer 5.
[0064] The electroplated tin layer 6 is selectively formed on the side wall surface of the cutting groove 41 and the corresponding pin 12 positions on the bottom surface of the cutting groove 41 not covered by the protective layer, which improves the side wettability of the pin 12, makes automatic visual inspection more accurate, and effectively improves the yield.
[0065] In some embodiments of this application, the electroplated tin layer 6 and the central rib 14 have a certain distance between them.
[0066] Specifically, the electroplated tin-climbing layer 6 and the central rib 14 have a certain distance between them. The distance avoids the electroplated tin-climbing layer 6 from contacting the central rib 14, eliminating the risk of short circuit. The electroplated tin-climbing layer 6 focuses on the side of the pin 12, with uniform wettability and high welding strength. At the same time, the clean side layout facilitates visual inspection.
[0067] In some embodiments of this application, the electroplated tin layer 6 comprises one or more layers, and the material of the electroplated tin layer 6 is one or more of the following: tin layer, copper layer, gold layer, nickel layer, and nickel alloy layer.
[0068] Next, refer to Figures 9 to 12 In step S107, a second cut is made along the cutting channel 4 between the frame units to form a discrete encapsulation structure.
[0069] The second cut separates the lead frame 1 along the cut 4 between the frame units, forming a discrete package structure, resulting in a single package structure, ensuring electrical isolation. Combined with the shielding of the protective material layer 5, the metal burrs 42 are completely removed after the second cut, preventing pin 12 bridging.
[0070] In some embodiments of this application, the specific processes for forming discrete packaging structures include: A second cut is made along the cutting groove 4 between the frame units to completely remove the protective material layer 5 formed at the bottom of the cutting groove 41, forming several discrete encapsulation structures.
[0071] Specifically, the preparation method follows a linear process of sequentially providing a frame, mounting the chip 2, forming a molding layer 3, making a first cut, applying a protective material layer 5, forming an electroplated tin layer 6, and making a second cut. This ensures that the components are processed in an orderly manner without interference. By limiting the depth of the cutting groove 41 to be less than the thickness of the lead frame 1 and the width of the cutting groove 41 to be greater than the width of the final cutting path 4, premature cutting of the connecting rib structure 13 is prevented. This provides leeway and space for the coating of the protective material layer 5 and the electroplating tin layer, reducing processing errors and costs. Through the partial coating of the protective material layer 5, the electroplating tin layer 6 is generated only at the pin 12 positions on the side wall surface of the cutting groove 41 and the bottom surface of the cutting groove 41 not covered by the protective material layer 5, eliminating burr bridging and ensuring electrical performance. The first cut is a pre-cut to form the cutting groove 41. The second cut finally separates the lead frame 1 to form a discrete package structure. Combined with the protective material layer, burrs are effectively controlled.
[0072] In the description of this specification, the references to terms such as "some embodiments," "other embodiments," "ideal embodiments," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example that are included in at least one embodiment or example of this application. In this specification, the illustrative descriptions of the above terms do not necessarily refer to the same embodiments or examples.
[0073] It should be noted that, where there is no conflict, the features in the different embodiments of this application described above can be combined with each other. Furthermore, in each of the above embodiments, the focus is on describing the differences from other embodiments; other specific descriptions of the same / similar parts between the embodiments can be referred to (or referenced) interchangeably. In addition, descriptions of well-known components and technologies have been omitted in the above description to avoid unnecessarily obscuring the concepts of this application.
[0074] Although this application has been disclosed above with reference to preferred embodiments, it is not intended to limit this application. Any person skilled in the art can make possible changes and modifications to the technical solutions of this application by utilizing the methods and techniques disclosed above without departing from the spirit and scope of this application. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of this application without departing from the content of the technical solutions of this application shall fall within the protection scope of the technical solutions of this application.
Claims
1. A method for preparing a packaging structure, characterized in that, Includes the following steps: A lead frame is provided, which is composed of several frame units, each frame unit including a base island and a pin, and the frame units are connected by a connecting rib structure. Chip mounting, wherein a plurality of the chips are bonded to the first surface of a plurality of the base islands; A molding compound is formed, which encapsulates the lead frame and the chip. A first cut is made at the corresponding position of the cutting channel between the frame units to form a cutting groove. The depth of the cutting groove is less than the thickness of the lead frame, and the width of the cutting groove is greater than the width of the final cutting channel. A protective material layer is applied to the bottom of the cutting groove to form a protective layer; An electroplated tin layer is formed at the corresponding pin positions on the side wall surface of the cutting groove and the bottom surface of the cutting groove that is not covered by the protective material layer; A second cut is made along the cutting lines between the frame units to form a discrete encapsulation structure.
2. The method for preparing the packaging structure according to claim 1, characterized in that, The lead frame also includes: The aforementioned base islands are arranged in rows and columns; Several of the aforementioned pins are arranged sequentially at intervals along the circumference of the base island; The pins of adjacent frame units are connected by the connecting rib structure to form the lead frame.
3. The method for preparing the packaging structure according to claim 2, characterized in that, Some of the aforementioned pins are located on both sides of the base island or around the base island.
4. The method for preparing the packaging structure according to claim 1, characterized in that, The frame unit includes at least one base island and multiple pins.
5. The method for preparing the packaging structure according to claim 1, characterized in that, The mounted chips specifically include: The second surface of the chip is bonded to the first surface of the base island; The first surface of the chip is connected to the first surface of the pin via a metal lead.
6. The method for preparing the packaging structure according to claim 1, characterized in that, The specific process for forming the cutting groove in the first cutting includes: A punching process is used to remove the plastic sealing material and part of the connecting rib structure in the thickness direction from the second surface of the connecting rib structure to form a cutting groove.
7. The method for preparing the packaging structure according to claim 1, characterized in that, The electroplated tin layer may consist of one or more layers.
8. The method for preparing the packaging structure according to claim 1, characterized in that, The specific processes for forming discrete packaging structures include: A second cut is made along the cutting grooves between the frame units to completely remove the protective material layer coated at the bottom of the cutting grooves, forming several discrete encapsulation structures.
9. The method for preparing the packaging structure according to claim 1, characterized in that, The protective material layer specifically includes printing ink and green paint.
10. The method for preparing the packaging structure according to claim 9, characterized in that, The process for forming the protective material layer includes one of screen printing, inkjet printing, and slot coating.
11. The method for preparing the packaging structure according to claim 1, characterized in that, The connecting reinforcement structure includes a central reinforcement and connecting support reinforcements for connecting pipe feet, and the protective material layer completely covers the surface of the central reinforcement.
12. The method for preparing the packaging structure according to claim 11, characterized in that, The width of the protective material layer at the bottom of the cutting groove is less than the width of the cutting channel but greater than the width of the central rib.
13. The method for preparing the packaging structure according to claim 11, characterized in that, The electroplated tin layer and the central rib have a certain distance between them.
14. The method for preparing the packaging structure according to claim 1, characterized in that, The protective material layer is spaced apart from the pin.