Leadframe packaging method and packaging structure

Abstract

The application provides a lead frame packaging method and packaging structure, and relates to the technical field of chip packaging. The method first provides a lead frame, and then forms accommodating grooves on the front surface of a plurality of pins. Then, a conductive ring is attached to the front surface of the pins in the plurality of accommodating grooves, wherein the conductive ring is further provided with a plurality of supporting portions, and each supporting portion is embedded between two adjacent pins. Then, a back adhesive layer is formed on the back surface of the connecting skeleton. Then, a chip is attached to the front surface. Then, a plastic encapsulation layer is formed on the front surface of the connecting skeleton. Then, the back adhesive layer is removed. Then, part of the pin area is removed, and finally, a back gold layer is formed on the back surface of the pin by electroplating. Compared with the prior art, the application improves the conductivity between the pins by setting the conductive ring, slows down the current skin effect, improves the electroplating quality, and improves the process efficiency. At the same time, the adhesion of the back adhesive film is improved by setting the supporting portion, and the risk of back overflow pollution during plastic encapsulation is reduced.

Description

Technical Field

[0001] This invention relates to the field of chip packaging technology, and more specifically, to a lead frame packaging method and packaging structure. Background Technology

[0002] With the rapid development of the semiconductor industry, dual flat no-lead (DFN) and quad flat no-lead (QFN) packages are widely used. They employ a wettable flank structure and are plated with a solderable coating on the sides to form three-dimensional solder joints. This enhances the connection strength between the component and the circuit board, reduces failures caused by poor soldering, and improves product reliability and stability. Furthermore, the wettable flanks allow the solder joints to flow upwards along the leads, forming clearly visible rounded corners. This facilitates the use of automated optical inspection (AOI) technology to inspect the solder joint quality without relying on X-ray images, thus improving inspection efficiency and safety while reducing inspection costs.

[0003] In existing DFN and QFN structures, the use of a backing film on the leadframe allows the bottom pins to remain unencapsulated during molding, while also providing support during wire bonding. Since there are gaps between the leadframe base island, connecting rods, and leads, a molding layer is needed to fill and protect them. However, during molding, the adhesive film in these gap areas is susceptible to mold flow impacts from the molding layer, which can easily lead to adhesive failure or even film detachment, creating gaps. This, in turn, results in excess adhesive on the back of the molding layer contaminating the leadframe pins / base islands.

[0004] Furthermore, during the subsequent electroplating process on the back of the pins, since the pins are independent of each other and not directly electrically connected, the skin effect is prone to occur, resulting in excessively high current density on the pin surface and excessively low current density inside the pin, which affects the plating quality and process efficiency. Summary of the Invention

[0005] The purpose of this invention is to provide a lead frame packaging method and packaging structure that can reduce the risk of backside adhesive contamination during molding, and also improve electroplating quality and process efficiency.

[0006] In a first aspect, the present invention provides a lead frame packaging method, comprising:

[0007] A lead frame is provided, wherein the lead frame includes a connecting skeleton and a plurality of pins, the connecting skeleton is provided with a mounting window, and the plurality of pins are hollowed out and disposed on at least two sides of the mounting window and connected to the connecting skeleton;

[0008] Receiving grooves are cut into the front side of the plurality of pins, wherein the receiving grooves are located at the end of the pins near the connecting frame;

[0009] A conductive ring is attached to a plurality of the receiving grooves along the front side of the pins so that the plurality of pins are electrically connected through the conductive ring. The conductive ring is also provided with a plurality of support portions, each of which is embedded between two adjacent pins.

[0010] An adhesive backing layer is formed on the back side of the connecting skeleton, wherein the adhesive backing layer extends to cover the base island, the plurality of the support portions and the plurality of the pins;

[0011] A chip is mounted on the lead frame, wherein the chip is electrically connected to the pins;

[0012] A molding compound is formed on the front side of the connection frame, wherein the molding compound fills the gaps between the plurality of pins and covers the chip, the conductive ring and the plurality of pins;

[0013] Remove the adhesive backing to expose the back of the pins and the connecting frame;

[0014] At least a portion of the back side of the pin is cut away to form a stepped groove that exposes the conductive ring;

[0015] A gold backing layer is formed by electroplating on the back side of the pin;

[0016] The molding layer and the pins are cut along a cutting path that corresponds to the inner sidewall of the receiving groove.

[0017] In an optional embodiment, the lead frame further includes a base island disposed in the mounting window, and a plurality of pins are cut out on at least two sides of the base island. The step of mounting the chip on the lead frame includes:

[0018] The back of the chip is attached to the front of the base island;

[0019] Multiple connecting arcs are formed on the front side of the chip, and the multiple connecting arcs are connected to the multiple pins respectively.

[0020] In an optional embodiment, the lead frame further includes connecting rods disposed around the base island and connected to the connecting skeleton. Prior to the step of attaching the conductive rings along the front side of the pins into the plurality of receiving grooves, the method further includes:

[0021] An avoidance groove is cut into the front side of the connecting rod, wherein the avoidance groove is used to accommodate the conductive ring.

[0022] In an optional embodiment, the conductive ring is in the shape of an integral rectangular frame, and the step of cutting accommodating grooves on the front side of the plurality of pins includes:

[0023] Receiving grooves are cut along the same straight direction on a plurality of pins located on the same side of the base island, wherein each receiving groove extends horizontally through the pin to accommodate the conductive ring.

[0024] In an optional embodiment, the conductive ring includes a plurality of sub-conductive elements arranged in a frame, each of the sub-conductive elements being connected to two adjacent pins. The step of cutting and forming receiving grooves on the front side of the plurality of pins includes:

[0025] Receiving grooves are intermittently cut along the same straight direction on a plurality of pins located on the same side of the base island, wherein two spaced-apart receiving grooves are cut on the front side of each pin, and each receiving groove is used to accommodate the end of the sub-conductive component.

[0026] In an optional embodiment, after the step of mounting the conductive ring along the front side of the pin in the plurality of receiving recesses, the method further includes:

[0027] A structural arc is formed by bonding wires between adjacent pins, wherein the two ends of each structural arc are respectively connected to the middle of two adjacent pins, so that the structural arc is arranged in an arch shape on the corresponding sub-conductive component.

[0028] In an optional embodiment, prior to the step of cutting an avoidance groove on the front side of the connecting rod, the method further includes:

[0029] The front side of the plurality of pins is thinned so that the height of the pins relative to the back side of the connecting frame is less than the height of the connecting rod relative to the back side of the connecting frame.

[0030] In an optional embodiment, prior to the step of mounting the conductive ring along the front side of the pin in the plurality of receiving recesses, the method further includes:

[0031] Multiple support portions are formed on the conductive ring, and the support portions are used to be embedded between two adjacent pins;

[0032] Support grooves are formed on the plurality of support portions, wherein the support grooves are used to accommodate the adhesive backing layer.

[0033] In an optional implementation, the step of mounting the chip on the front side of the base island includes:

[0034] The back of the chip is mounted on the base island;

[0035] Multiple connecting arcs are formed on the front side of the chip, and the multiple connecting arcs are connected to the multiple pins respectively.

[0036] In an optional embodiment, the step of mounting the conductive ring along the front side of the pin in the plurality of accommodating recesses includes:

[0037] A conductive adhesive layer is formed by dispensing adhesive into the plurality of said receiving grooves;

[0038] The conductive rings are attached to the plurality of receiving grooves so that the conductive rings are fixedly bonded to the receiving grooves by the conductive adhesive layer.

[0039] In an optional implementation, the step of removing at least a portion of the back side of the pin includes:

[0040] A protective layer is formed on the back side of the pin;

[0041] An etched opening is formed on the protective layer;

[0042] The back side of the pin is etched along the etch opening to form a stepped groove that exposes the conductive ring.

[0043] In an optional implementation, the step of removing at least a portion of the back side of the pin includes:

[0044] Cut away a portion of the back side of the pin to form a stepped groove that exposes the conductive ring.

[0045] Secondly, the present invention provides a packaging structure, which is prepared using the lead frame packaging method described in the foregoing embodiments, the packaging structure comprising:

[0046] A lead frame, the lead frame including a plurality of pins;

[0047] A chip, which is mounted on a lead frame and electrically connected to a plurality of said pins;

[0048] A molding compound covers the lead frame and the chip, with the back sides of the plurality of pins exposed outside the molding compound;

[0049] A gold backing layer, which is electroplated and formed on the back side of the pin.

[0050] In an optional embodiment, the lead frame further includes a base island, with a plurality of pins distributed on at least two sides of the base island, the chip mounted on the front side of the base island, the molding compound covering the front side and sidewalls of the base island, and the back gold layer also electroplated to form on the back side of the base island.

[0051] In an alternative implementation, a stepped groove is formed on the back side of each pin, and the back gold layer extends to the sidewall of the stepped groove.

[0052] In an optional embodiment, the encapsulation layer protrusion is disposed between two adjacent stepped grooves.

[0053] In an optional implementation, a structural groove is also formed on the back side of the pin, the structural groove communicating with the stepped groove.

[0054] In an optional embodiment, a structural groove is also formed on the back side of the pin, the structural groove extending to the edge sidewall of the pin.

[0055] The beneficial effects of the embodiments of the present invention include:

[0056] The leadframe packaging method and packaging structure provided in this invention first provide a leadframe with mounting windows on its connecting skeleton. Multiple pins are hollowed out and disposed at least on both sides (e.g., around the perimeter) of the mounting windows and connected to the connecting skeleton. Then, receiving grooves are formed on the front side of the multiple pins using a cutting process. These receiving grooves are located at the ends of the pins closest to the connecting skeleton. Next, pre-prepared conductive rings are mounted along the front side of the pins into the multiple receiving grooves, enabling electrical connection between the multiple pins through the conductive rings. The conductive rings also have multiple support portions, each precisely embedded between two adjacent pins. Then, an adhesive layer is formed on the back side of the connecting skeleton, extending to cover the support portions and the multiple pins for adhesive bonding and fixation. Due to the large contact area of ​​the adhesive layer, the bonding and fixation effect is better. Next, a chip is mounted on the front side of the base island, making the chip electrically connected to the pins. Finally, a molding compound is formed on the front side of the connecting skeleton, filling the gaps between the multiple pins and covering the base island, chip, conductive rings, and multiple pins. Then, the adhesive backing layer is removed, exposing the pins and the back of the connecting frame. Next, a portion of the pin area is cut away to form a stepped groove exposing the conductive ring. Finally, a gold backing layer is electroplated onto the back of the pins before cutting. Compared to existing technologies, this invention, by setting conductive rings, achieves electrical connection between multiple pins, thereby improving the conductivity between pins. During electroplating, multiple pins are directly electrically connected to each other, mitigating the skin effect, improving electroplating quality, and increasing process efficiency. Simultaneously, by setting a support portion, the adhesive film can contact and bond with the support portion, improving the adhesive adhesion of the adhesive film, thereby reducing the risk of adhesive film failure due to molding flow impact during encapsulation, and reducing the risk of back adhesive overflow contamination during encapsulation. Attached Figure Description

[0057] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0058] Figure 1a This is a flowchart illustrating the steps of the lead frame packaging method provided in the first embodiment of the present invention.

[0059] Figure 1b This is a schematic diagram of the lead frame provided in step S1 of the lead frame packaging method provided in the first embodiment of the present invention;

[0060] Figure 1c This is a cross-sectional schematic diagram of the lead frame provided in step S1 of the lead frame packaging method provided in the first embodiment of the present invention;

[0061] Figure 2a This is a partial schematic diagram corresponding to step S2 in the lead frame packaging method provided in the first embodiment of the present invention;

[0062] Figure 2b This is a cross-sectional schematic diagram corresponding to step S2 in the lead frame encapsulation method provided in the first embodiment of the present invention;

[0063] Figure 3a This is a partial schematic diagram of step S3 in the lead frame packaging method provided in the first embodiment of the present invention.

[0064] Figure 3b This is a cross-sectional schematic diagram of step S3 in the lead frame encapsulation method provided in the first embodiment of the present invention.

[0065] Figure 4a This is a partial schematic diagram of step S4 in the lead frame encapsulation method provided in the first embodiment of the present invention.

[0066] Figure 4b This is a cross-sectional schematic diagram of step S4 in the lead frame encapsulation method provided in the first embodiment of the present invention.

[0067] Figure 4c This is a schematic diagram of the conductive ring structure in step S4 of the lead frame packaging method provided in the first embodiment of the present invention;

[0068] Figure 5a This is a partial schematic diagram of step S5 in the lead frame encapsulation method provided in the first embodiment of the present invention.

[0069] Figure 5bThis is a cross-sectional schematic diagram of step S5 in the lead frame encapsulation method provided in the first embodiment of the present invention.

[0070] Figure 6 This is a cross-sectional schematic diagram of step S6 in the lead frame encapsulation method provided in the first embodiment of the present invention.

[0071] Figure 7a This is a partial schematic diagram of step S7 in the lead frame encapsulation method provided in the first embodiment of the present invention.

[0072] Figure 7b This is a cross-sectional schematic diagram of step S7 in the lead frame encapsulation method provided in the first embodiment of the present invention.

[0073] Figure 8a This is a schematic diagram of the first process cross section corresponding to step S8 in the lead frame packaging method provided in the first embodiment of the present invention.

[0074] Figure 8b This is a schematic diagram of the second process cross section corresponding to step S8 in the lead frame packaging method provided in the first embodiment of the present invention.

[0075] Figure 9 This is a cross-sectional schematic diagram of step S9 in the lead frame encapsulation method provided in the first embodiment of the present invention.

[0076] Figure 10 This is a cross-sectional schematic diagram of step S10 in the lead frame packaging method provided in the first embodiment of the present invention.

[0077] Figure 11 This is a schematic diagram of a first packaging structure provided in the first embodiment of the present invention;

[0078] Figure 12 This is a schematic diagram of the second packaging structure provided in the first embodiment of the present invention;

[0079] Figure 13a This is a schematic diagram of the third packaging structure provided in the first embodiment of the present invention;

[0080] Figure 13b This is a schematic diagram of the fourth packaging structure provided in the first embodiment of the present invention;

[0081] Figure 13c This is a partial schematic diagram of the fifth packaging structure provided in the first embodiment of the present invention;

[0082] Figure 14 This is a partial schematic diagram corresponding to step S2 in the lead frame packaging method provided in the second embodiment of the present invention;

[0083] Figure 15This is a partial schematic diagram of step S3 in the lead frame encapsulation method provided in the second embodiment of the present invention.

[0084] Figure 16 This is a cross-sectional schematic diagram of step S9 in the lead frame encapsulation method provided in the third embodiment of the present invention.

[0085] Figure 17 This is a cross-sectional schematic diagram of step S10 in the lead frame encapsulation method provided in the third embodiment of the present invention.

[0086] Figure 18 A schematic diagram of the first packaging structure provided in the third embodiment of the present invention;

[0087] Figure 19 This is a schematic diagram of a second packaging structure provided in the third embodiment of the present invention.

[0088] Icons: 100-Package structure; 110-Lead frame; 111-Connector skeleton; 112-Base island; 113-Pin; 114-Accommodation groove; 115-Connector rod; 116-Allowing groove; 117-Structural groove; 120-Conductive ring; 121-Support part; 122-Support groove; 123-Conductive adhesive layer; 124-Sub-conductive component; 125-Structural line arc; 130-Back adhesive layer; 140-Chip; 141-Connector line arc; 150-Encapsulation layer; 160-Step groove; 161-Protective layer; 170-Back gold layer. Detailed Implementation

[0089] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0090] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0091] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0092] In the description of this invention, it should be noted that if terms such as "upper," "lower," "inner," or "outer" are used to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of this invention is usually placed, they are only for the convenience of describing this invention and simplifying the description, and 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 of this invention.

[0093] Furthermore, the terms "first" and "second" are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0094] As disclosed in the background section, in existing leadframe packaging processes, gaps exist between pins, connecting rods, and base islands, requiring a molding compound for filling and protection, as well as structural support. However, during molding, the high pressure can easily cause mold flow impacts, making the adhesive film in the gap areas susceptible to these impacts. This can lead to adhesive failure or even film detachment, creating gaps. Consequently, excess adhesive on the back of the molding compound can contaminate the pins / base islands on the back of the leadframe, affecting subsequent electroplating.

[0095] Furthermore, during the subsequent electroplating process on the back of the pins, since the pins are independent of each other and not directly electrically connected, i.e. there are gaps between the pins, the pins can only act as conductive leads through the connecting frame skeleton. However, the lateral contact area between the skeleton and the pins is small, resulting in poor electrical connection performance between the pins. This easily leads to the skin effect, causing the current density on the pin surface to be too high and the current density inside to be too low, thereby affecting the plating quality and process efficiency.

[0096] To address the aforementioned issues, embodiments of the present invention provide a lead frame encapsulation method and encapsulation structure. It should be noted that, without conflict, the features in the embodiments of the present invention can be combined with each other.

[0097] First Embodiment

[0098] See Figure 1a This invention provides a lead frame 110-frame packaging method that can reduce the risk of backside adhesive contamination during molding, and also improves electroplating quality and process efficiency.

[0099] This invention provides a lead frame 110 packaging method for fabricating a packaging structure 100. The method includes the following steps:

[0100] S1: Provide a lead frame 110.

[0101] See Figure 1b and Figure 1c The lead frame 110 includes a connecting frame 111, a base island 112, and multiple pins 113. The connecting frame 111 has mounting windows, the base island 112 is disposed within these windows, and the multiple pins 113 are hollowed out and disposed on at least two sides of the base island 112, connecting to the connecting frame 111. It should be noted that the basic structure of the lead frame 110 is consistent with a conventional package frame. Multiple rectangular mounting windows can be provided on the lead frame 110, each containing a base island 112 and multiple pins 113. The multiple pins 113 can be distributed around the base island 112, facilitating the subsequent formation of a QFN package structure 100. Alternatively, the multiple pins 113 can be distributed only on opposite sides of the base island 112, facilitating the subsequent formation of a DFN package structure 100. This embodiment uses the distribution of multiple pins 113 around the base island 112 as an example.

[0102] S2: A receiving groove 114 is formed by cutting the front side of multiple pins 113.

[0103] See Figure 2a and Figure 2b The receiving groove 114 is located at the end of the pin 113 near the connecting frame 111. Specifically, the receiving groove 114 is formed by cutting at the tail end of the pin 113 through a cutting process (such as laser cutting or mechanical cutting), wherein the tail end of the pin 113 is connected to one end of the connecting frame 111. In actual cutting, the receiving groove 114 can be formed by cutting along the same straight line on multiple pins 113 located on the same side of the base island 112, wherein each receiving groove 114 penetrates the pin 113 horizontally to accommodate the subsequent conductive ring 120.

[0104] It should be noted that the cutting path here is rectangular, so that the pins 113 around the base island 112 can be cut to form receiving grooves 114. In actual cutting, four cuts can be performed in sequence to complete the cutting action of the pins 113 around the base island 112.

[0105] Furthermore, the lead frame 110 also includes connecting rods 115, which are disposed around the base island 112 and connected to the connecting frame 111, thereby providing support for the base island 112. When the receiving groove 114 is cut here, a clearance groove 116 can also be cut on the front side of the connecting rod 115, where the clearance groove 116 also serves to accommodate the conductive ring 120. Moreover, the clearance groove 116 and the receiving groove 114 can be cut along the same rectangular cutting path, meaning the clearance groove 116 and the receiving groove 114 on the same side can extend in the same direction.

[0106] It should be noted that before forming the clearance groove 116, i.e., before cutting to form the receiving groove 114, the front side of the multiple pins 113 can be thinned so that the height of the pins 113 relative to the back side of the connecting frame 111 is less than the height of the connecting rod 115 relative to the back side of the connecting frame 111. Specifically, the height of the connecting rod 115 is relatively larger here, which can improve the structural strength of the connecting rod 115 and better form the clearance groove 116. Furthermore, the depth of the clearance groove 116 can be greater than the depth of the conductive ring 120. Therefore, after the conductive ring 120 is mounted, there will also be a groove of a certain depth on the top of the conductive ring 120. In the subsequent molding process, this can improve the bonding force between the molding layer 150 and the connecting rod 115 and prevent delamination of the molding.

[0107] S3: The conductive ring 120 is mounted along the front side of the pin 113 in a plurality of receiving grooves 114.

[0108] See Figure 4c After the conductive ring 120 is attached, multiple pins 113 can be electrically connected through the conductive ring 120. The conductive ring 120 also has multiple support portions 121, each embedded between two adjacent pins 113. Specifically, the conductive ring 120 can be pre-fabricated. Here, the conductive ring 120 can be in the form of an integral rectangular frame, its shape adapted to the cutting path when cutting the receiving groove 114. Therefore, the conductive ring 120 can be integrally installed into multiple receiving grooves 114 and clearance grooves 116, thereby achieving the installation and fixation of the conductive ring 120.

[0109] See Figure 3a and Figure 3b In the actual mounting of the conductive ring 120, a conductive adhesive layer 123 can first be formed by applying adhesive or coating in multiple receiving grooves 114. Then, the conductive ring 120 is mounted in the corresponding receiving grooves 114, thereby fixing the conductive ring 120 in the receiving grooves 114 through the conductive adhesive layer 123. The bonding and fixing are then achieved through a baking process. The thickness and width of the conductive ring 120 can be adapted to the depth and width of the receiving grooves 114, allowing the conductive ring 120 to be flush with the pins 113. Here, the conductive adhesive layer 123 has the characteristics of a self-adhesive (semi-cured state), serving both adhesive and conductive functions. Alternatively, the conductive adhesive layer 123 can also be a conductive coating material, prepared using a coating process and then cut to form grooves, thus forming a conductive coating material in the receiving grooves 114. This conductive coating or conductive adhesive layer 123 can be a mixed adhesive layer composed of butyl acrylate, isooctyl acrylate / epoxy resin, conductive particles, and polymers.

[0110] It should be noted that the conductive ring 120 can also be prepared in advance. Between the conductive rings 120, multiple spaced support portions 121 can be formed on the conductive ring 120. The support portions 121 are used to be embedded between two adjacent pins 113. Then, grooves are opened on the multiple support portions 121 to form support grooves 122. The support grooves 122 are used to accommodate the subsequently prepared backing adhesive layer 130, thereby improving the bonding force between the support portions 121 and the backing adhesive layer 130.

[0111] S4: An adhesive backing layer 130 is formed on the back side of the connecting skeleton 111.

[0112] See Figure 4a and Figure 4b The adhesive layer 130 extends to cover the base island 112, multiple support portions 121, and multiple pins 113. Specifically, an adhesive film can be applied to the back of the connecting frame 111 using a laminating machine. This adhesive film ensures that the back of the pins 113 is not encapsulated during molding and provides support during the wire bonding process. The adhesive film can simultaneously cover the back of the base island 112 and the multiple pins 113, and also cover the support grooves 122 on the support portions 121. By providing the support grooves 122, the bonding force between the adhesive film and the support portions 121 can be further enhanced, resulting in better adhesion and fixation of the adhesive film.

[0113] S5: Attach chip 140 to lead frame 110, wherein chip 140 is electrically connected to pin 113.

[0114] See Figure 5a and Figure 5b Specifically, the back side of chip 140 can be first mounted on base island 112, while the front side of chip 140 has pads for electrical connections. Then, through wire bonding, multiple connection arcs 141 are formed on the front side of chip 140, and each of the multiple connection arcs 141 can be connected to multiple pins 113 respectively. In this embodiment, connection arcs 141 can be formed by bonding wires around all four sides of chip 140. When using a DFN structure, connection arcs 141 can be formed only on the two edges of the front side of chip 140.

[0115] In other preferred embodiments of the present invention, the lead frame 110 may also adopt a base island-less design, that is, no base island and connecting rod are provided in the mounting window, and the chip 140 can be directly mounted on multiple pins 113 by flip-chip process, thus realizing the electrical connection between the chip 140 and multiple pins 113.

[0116] S6: A molding layer 150 is formed on the front side of the connecting skeleton 111.

[0117] See Figure 6The molding compound 150 fills the gaps between multiple pins 113 and covers the base island 112, chip 140, conductive ring 120, and multiple pins 113. Specifically, using a molding process, molding liquid is filled and pressure injection is performed to fill the gaps between pins 113 and protect the structure of chip 140 to form the molding compound 150. Since the adhesive bonding force of the backing film is enhanced by the support portion 121 and the support groove 122, the mold flow impact generated during molding will not cause the backing film to fail, avoiding the situation where the backing film falls off and forms gaps, resulting in molding compound overflow contamination.

[0118] It should be noted that, since the conductive ring 120 is flush with the front of the pin 113, and the thickness of the pin 113 is less than the thickness of the connecting rod 115, the conductive ring 120 does not completely fill the clearance groove 116. Thus, a groove is formed on the conductive ring 120, which can improve the bonding force between the molding layer 150 and the connecting rod 115, and improve the bonding force between the lead frame 110 and the four corners of the molding layer 150, thus avoiding delamination of the molding.

[0119] S7: Remove the adhesive backing layer 130 to expose the back of the pins 113 and the connecting frame 111.

[0120] See Figure 7a and Figure 7b Specifically, the adhesive film can be removed using a film peeling machine to expose the back of the pins 113, the base island 112 and the connecting frame 111, as well as the support portion 121 and the support groove 122.

[0121] S8: At least a portion of the back side of pin 113 is removed to form a stepped groove 160 that exposes the conductive ring 120.

[0122] See Figure 8a The stepped groove can be formed using an etching process. Specifically, a protective layer 161, which can be photoresist, is first formed on the back of the pin. Then, an etching opening is formed on the protective layer 161, and the back of the pin is etched along the etching opening, using the photoresist film on the conductive ring 120 as the etching stop layer, thereby forming a stepped groove that exposes the conductive ring. Finally, the protective layer is removed to complete the fabrication of the stepped groove 160. The stepped groove 160 needs to extend to the connecting frame 111, and the width of the stepped groove 160 is greater than the minimum spacing between the conductive rings 120 in two adjacent mounting windows, so that the stepped groove 160 can expose the conductive adhesive layer 123 at the bottom of the conductive ring 120. At this time, the conductive adhesive layer 123 at the bottom of the conductive ring 120 is the cutting stop layer during cutting, which can effectively prevent the pin 113 from being over-cut, thereby forming a half-cut state.

[0123] See Figure 8bOf course, in other preferred embodiments of the present invention, a cutting process (using a laser cutting machine, plasma cutting machine or mechanical cutting machine, etc.) can also be used to complete the first cutting of a wider area. After the first cutting, a wider cutting blade can be used for local cutting to form a stepped groove 160.

[0124] S9: A back gold layer 170 is formed by electroplating on the back side of pin 113.

[0125] See Figure 9 Specifically, the lead frame 110 is electroplated using an electroplating process. The lead frame 110 is electrically coupled to the negative electrode of the conductive plating equipment, and the positive electrode is coupled to the conductive plating material. Current is applied to the lead frame 110, causing the electroplating material to deposit on the metal surface of the lead frame 110, that is, on the surface of the pins 113, the base island 112, and the connecting skeleton 111 exposed on the molding compound 150, forming a metal layer. The back gold layer 170 can be at least one of tin, gold, silver, palladium, and nickel. Since the pins 113 are designed with conductive rings 120 and conductive adhesive layers 123, the current density between multiple pins 113 during the electroplating process can be increased, and the current density and electrical connection performance inside the molding compound 150 can be improved, reducing the skin effect and improving the quality of the electroplated metal layer.

[0126] Furthermore, since a support groove 122 is also formed on the support portion 121 at this time, and the depth of the support groove 122 is greater than the depth of the stepped groove 160, the support groove 122 can act as a flow channel, thereby changing the direction of current / liquid transmission towards the pin 113, improving the plating quality on the surface of the pin 113, and improving electroplating efficiency. Moreover, the extending direction of the support groove 122 is consistent with the extending direction of the receiving groove 114, which can better serve as an electroplating flow channel and prevent overflow into the support groove 122 during plastic encapsulation.

[0127] S10: Cut the molding layer 150 and the pin 113 along the cutting path.

[0128] See Figure 10 Specifically, the cutting path corresponds to the sidewall of the receiving groove 114 near the base island 112. A narrower cutting blade can be used for secondary cutting, with the cutting path positioned corresponding to the inner sidewall of the receiving groove 114. This allows cutting along the sidewall of the conductive adhesive layer 123, preserving the sidewall of the stepped groove 160, forming the stepped pin 113 structure, and cutting the package structure 100 into individual products, thus completing the process.

[0129] See also Figure 1b , Figure 2a , Figure 3a , Figure 4a , Figure 4c , Figure 5a and Figure 11This invention also provides a packaging structure 100, which is prepared using the aforementioned steps S1-S9. The packaging structure 100 includes a lead frame 110, a conductive ring 120, a chip 140, a molding layer 150, and a back gold layer 170. The lead frame 110 includes a connecting frame 111, a base island 112, and multiple pins 113. The connecting frame 111 has a mounting window, and the base island 112 is disposed within the mounting window. Multiple pins 113 are hollowed out and disposed on at least two sides of the base island 112, and connected to the connecting frame 111. Each pin 113 has a receiving groove 114 cut into its front side, and the receiving groove 114 is located at the end of the pin 113 closest to the connecting frame 111. The conductive ring 120 is mounted along the front side of the pin 113 in the multiple receiving grooves 114, so that the multiple pins 113... Electrically connected via conductive ring 120, wherein the conductive ring 120 is also provided with multiple support portions 121, each support portion 121 being embedded between two adjacent pins 113; chip 140 is mounted on the front side of base island 112 and electrically connected to pins 113; molding compound 150 is disposed on the front side of connecting frame 111 and fills the gap between multiple pins 113, and molding compound 150 at least partially covers base island 112, chip 140, conductive ring 120 and multiple pins 113, the back side of base island 112, chip 140, conductive ring 120 and multiple pins 113 are exposed to molding compound 150, and the back side of each pin 113 is partially cut to form a stepped groove 160 exposing conductive ring 120; back gold layer 170 is electroplated on the back side of pins 113 and base island 112 and extends to the sidewall of stepped groove 160.

[0130] Furthermore, the lead frame 110 also includes a connecting rod 115, which is disposed around the base island 112 and connected to the connecting frame 111, thereby supporting the base island 112. The connecting rod 115 also has a clearance groove 116 cut together with the receiving groove 114, and the conductive ring 120 can be simultaneously mounted in the clearance groove 116.

[0131] In this embodiment, the height of pin 113 relative to the back of connecting frame 111 is less than the height of connecting rod 115 relative to the back of connecting frame 111. Specifically, the connecting rod 115 is taller here, which improves the structural strength of the connecting rod 115 and allows for better formation of the clearance groove 116. The depth of the clearance groove 116 is greater than the depth of the conductive ring 120. Therefore, after the conductive ring 120 is mounted, there will also be a groove of a certain depth on the top of the conductive ring 120. The molding layer 150 also covers the connecting rod 115, thus improving the bonding force between the molding layer 150 and the connecting rod 115 and preventing delamination of the molding layer.

[0132] In other preferred embodiments of the present invention, the lead frame 110 may also adopt a base island-less design, that is, no base island and connecting rod are provided in the mounting window, and the chip 140 can be directly mounted on multiple pins 113 by flip-chip process, thus realizing the electrical connection between the chip 140 and multiple pins 113.

[0133] In this embodiment, each receiving groove 114 extends horizontally through the pin 113. The conductive ring 120 is an integral rectangular frame shape, used to simultaneously accommodate multiple receiving grooves 114 and connect multiple pins 113. Specifically, the conductive ring 120 can be simultaneously mounted in multiple receiving grooves 114 and clearance grooves 116, which can improve the connection structure strength between multiple pins 113, thereby improving the structural strength of the entire lead frame 110 and preventing deformation during subsequent plastic encapsulation.

[0134] Please continue reading Figure 10 , Figure 12 and Figure 13a The present invention also provides another packaging structure 100, which is prepared by the lead frame 110 frame packaging method as described in the above embodiments. Specifically, it can be prepared by steps S1-S10. The packaging structure 100 includes a lead frame 110, a chip 140 and a back gold layer 170. The lead frame 110 includes a base island 112 and a plurality of pins 113. The plurality of pins 113 are hollowed out and disposed on at least two sides of the base island 112, and a stepped groove 160 is formed on the back side of each pin 113. The chip 140 is mounted on the front side of the base island 112 and electrically connected to the pins 113. The back gold layer 170 is electroplated and formed on the back side of the pins 113 and the base island 112, and extends to the side wall of the stepped groove 160.

[0135] It should be noted that the package structure 100 here refers to a packaged product, which can be a QFN package structure 100 (e.g., ...). Figure 12 ), or it can be a DFN package structure 100 (such as Figure 13a ).

[0136] Furthermore, a stepped groove 160 is formed on the back side of each pin 113, and the back gold layer 170 can extend to the sidewall of the stepped groove 160.

[0137] See Figure 13b In other preferred embodiments of the present invention, when the stepped groove 160 is formed by etching, only the pin 113 can be etched, that is, the opening on the protective layer 161 only exposes the pin 113, thereby retaining the molding layer 150, that is, the molding layer 150 protrudes between two adjacent stepped grooves 160, without the need to remove the molding layer 150, thus saving process steps.

[0138] See Figure 13cIn other preferred embodiments of the present invention, when the stepped groove 160 is formed by etching, the etching solution will also perform anisotropic etching on the sidewall of the stepped groove 160, thereby forming a rounded corner structure or a groove and other undercut phenomenon on the sidewall. At the same time, a back gold layer 170 is formed on the back of the pin 113, and the back gold layer 170 extends to the sidewall of the stepped groove, which can further improve the welding bond between the pin 113 and the back gold layer 170.

[0139] In summary, the lead frame 110 packaging method and packaging structure 100 provided in this embodiment of the invention first provide a lead frame 110. The connecting skeleton 111 of the lead frame 110 has a mounting window, a base island 112 is disposed within this mounting window, and multiple pins 113 are hollowed out and disposed on at least two sides (e.g., around the perimeter) of the base island 112, and connected to the connecting skeleton 111. Then, receiving grooves 114 are formed on the front side of the multiple pins 113 using a cutting process. These receiving grooves 114 are located at the end of the pin 113 closest to the connecting skeleton 111. Then, a pre-prepared conductive ring 120 is attached along the front side of the pins 113 into the multiple receiving grooves 114, so that the multiple pins 113 can be electrically connected through the conductive ring 120. The conductive ring 120 also has multiple support portions 121, each support portion 121 being precisely embedded between two adjacent pins 113. Then, an adhesive layer 130 is formed on the back side of the connecting frame 111. This adhesive layer 130 extends to cover the base island 112, the support portion 121, and the multiple pins 113, achieving adhesive bonding and fixation. Due to the large contact area of ​​the adhesive layer 130, the bonding and fixation effect is better. Next, a chip 140 is mounted on the front side of the base island 112, making the chip 140 electrically connected to the pins 113. Then, a molding compound 150 is formed on the front side of the connecting frame 111, wherein the molding compound 150 can fill the gaps between the multiple pins 113 and cover the base island 112, the chip 140, the conductive ring 120, and the multiple pins 113. Then, the adhesive layer 130 is removed, thereby exposing the pins 113, the base island 112, and the back side of the connecting frame 111. Next, a portion of the pin 113 is cut away to form a stepped groove 160 exposing the conductive ring 120. Finally, a back gold layer 170 is electroplated on the back of the pin 113 and the base island 112. Compared to the prior art, this embodiment of the invention, by setting the conductive ring 120, achieves electrical connection between multiple pins 113, increasing the current density inside the packaging structure, thereby improving the conductivity between the pins 113 located inside the molding layer 150. During the electroplating process, multiple pins 113 are directly electrically connected to each other, achieving an increase in internal current density, mitigating the skin effect, improving electroplating quality, and increasing process efficiency. At the same time, by setting the support portion 121, the adhesive film can contact and adhere to the support portion 121, improving the adhesive bonding force of the adhesive film, thereby reducing the risk of adhesive film adhesion failure caused by mold flow impact during molding, and reducing the risk of back adhesive overflow contamination during molding.

[0140] Second Embodiment

[0141] This invention provides a lead frame 110-frame packaging method, the basic steps and principles of which are the same as those of the first embodiment. For the sake of brevity, any parts not mentioned in this embodiment can be referred to the corresponding content in the first embodiment. The difference between this embodiment and the first embodiment lies in steps S2 and S3.

[0142] The lead frame 110-frame packaging method provided in this embodiment of the invention includes the following steps:

[0143] S1: Provide a lead frame 110.

[0144] S2: A receiving groove 114 is formed by cutting the front side of multiple pins 113, wherein the receiving groove 114 is located at the end of the pin 113 near the connecting frame 111.

[0145] See Figure 14 and Figure 15 Specifically, the conductive ring 120 may include a plurality of sub-conductive elements 124 arranged in a frame, each sub-conductive element 124 being in the shape of a conductive rod, and each sub-conductive element 124 being used to connect two adjacent pins 113. When actually cutting to form the receiving grooves 114, the receiving grooves 114 can be intermittently cut along the same straight direction on the plurality of pins 113 located on the same side of the base island 112, wherein two spaced-apart receiving grooves 114 are cut on the front side of each pin 113, and each receiving groove 114 is used to accommodate the end of the sub-conductive element 124.

[0146] It should be noted that the intermittent cutting here refers to retaining the middle part of the pin 113 while cutting two spaced-apart receiving grooves 114 on both sides.

[0147] S3: The step of mounting the conductive ring 120 along the front side of the pin 113 in the plurality of receiving grooves 114.

[0148] Please continue reading Figure 14 and Figure 15 Specifically, multiple sub-conductive components 124 can be sequentially placed into the receiving grooves 114. The two ends of each sub-conductive component 124 are respectively inserted into the two receiving grooves 114 on the adjacent pins 113. The sub-conductive components 124 can realize the electrical connection between two adjacent pins 113, and multiple sub-conductive components 124 can realize the electrical connection between multiple pins 113.

[0149] It should be noted that a sub-conductive component 124 is also provided on the connecting rod 115. The sub-conductive component 124 on the connecting rod 115 can be bent, thereby ensuring that multiple sub-conductive components 124 are distributed in a rectangular frame shape.

[0150] Furthermore, after the conductive ring 120 is assembled, a structural arc 125 can be formed by wiring between two adjacent pins 113, wherein the two ends of each structural arc are connected to the middle of the two adjacent pins 113 respectively, so that the structural arc 125 is arranged in an arch shape above the corresponding sub-conductive component 124.

[0151] It should be noted that multiple structural arc lines 125 can be distributed in a fence-like pattern around the base island 112, thereby mitigating the impact of the molding liquid during encapsulation. Furthermore, these structural arc lines 125 are conductive arc lines, which can further improve the electrical connection between adjacent pins 113 and enhance the electroplating effect. During the final cutting to form the packaged product, the cutting path is also located inside the structural arc lines 125, allowing the structural arc lines 125 to be cut and removed along with the package.

[0152] Steps S4-S10 can be referred to the first embodiment.

[0153] Please continue reading Figure 11 , Figure 14 and Figure 15 This embodiment of the invention also provides a packaging structure 100. The basic structure, principle and technical effects of the packaging structure 100 are the same as those of the first embodiment. For the sake of brevity, any parts not mentioned in this embodiment can be referred to the corresponding content in the first embodiment.

[0154] The package structure 100 includes a lead frame 110, a conductive ring 120, a chip 140, a molding layer 150, and a back gold layer 170. The lead frame 110 includes a connecting frame 111, a base island 112, and multiple pins 113. The connecting frame 111 has a mounting window, and the base island 112 is disposed within the mounting window. The multiple pins 113 are hollowed out and disposed on at least two sides of the base island 112 and connected to the connecting frame 111. Each pin 113 has a receiving groove 114 cut on its front side, and the receiving groove 114 is located at the end of the pin 113 closest to the connecting frame 111. The conductive ring 120 is mounted in the multiple receiving grooves 114 along the front side of the pins 113 so that the multiple pins 113 are electrically connected through the conductive ring 120. The conductive ring 120 also has... A plurality of support portions 121 are provided, each support portion 121 being embedded between two adjacent pins 113; a chip 140 is mounted on the front side of the base island 112 and electrically connected to the pins 113; a molding compound 150 is disposed on the front side of the connecting frame 111 and fills the gap between the plurality of pins 113, and the molding compound 150 at least partially covers the base island 112, the chip 140, the conductive ring 120 and the plurality of pins 113, the back side of the base island 112, the chip 140, the conductive ring 120 and the plurality of pins 113 is exposed outside the molding compound 150, and the back side of each pin 113 is partially cut to form a stepped groove 160 exposing the conductive ring 120; a back gold layer 170 is electroplated on the back side of the pins 113 and the base island 112 and extends to the sidewall of the stepped groove 160.

[0155] In this embodiment, the conductive ring 120 includes a plurality of sub-conductive elements 124 arranged in a frame. Each sub-conductive element 124 is connected to two adjacent pins 113. The front side of each pin 113 is cut to form two spaced-apart receiving grooves 114. The two ends of each sub-conductive element 124 are respectively received into the receiving grooves 114 on the two adjacent pins 113.

[0156] Furthermore, a structural arc 125 is formed between every two adjacent pins 113 by wire bonding. The two ends of each structural arc 125 are respectively connected to the middle of the two adjacent pins 113, so that the structural arc 125 is arranged in an arch shape above the corresponding sub-conductive component 124. By setting the structural arc 125, it can play a role in resisting mold flow impact, improving the overall structural strength, and ensuring the uniformity of molding.

[0157] Third Embodiment

[0158] This invention provides a lead frame 110-frame packaging method, the basic steps and principles of which are the same as those of the first embodiment. For the sake of brevity, any parts not mentioned in this embodiment can be referred to the corresponding content in the first embodiment. The difference between this embodiment and the first embodiment lies in step S9.

[0159] Steps S1-S8 can be referred to in the first embodiment. This method also includes the following steps:

[0160] S9: A back gold layer 170 is formed by electroplating on the back of pin 113 and base island 112.

[0161] See Figure 16 Specifically, before electroplating, a structural groove 117 needs to be locally cut on the pin 113 to form a groove that connects to the stepped groove 160. Preferably, the structural groove 117 is located in the middle of the pin 113 and is a semi-circular groove. Then, the electroplating process is completed, and the back gold layer 170 can simultaneously cover the stepped groove and the structural groove 117.

[0162] S10: Cut the molding layer 150 and the pin 113 along the cutting path.

[0163] See Figure 17 Specifically, the cutting path can correspond to the sidewall of the receiving groove 114 near the base island 112, thereby preserving part of the bottom wall of the stepped groove 160 and forming a stepped structure. That is, a narrower cutting blade can be used for secondary cutting, with the cutting path corresponding to the inner sidewall of the receiving groove 114, thereby cutting along the sidewall of the conductive adhesive layer 123, preserving the sidewall of the stepped groove 160, forming a stepped pin 113 structure, and cutting the package structure 100 into individual products, completing the process.

[0164] See Figure 19 In other preferred embodiments, the cutting path may also correspond to the sidewall of the stepped groove 160, thus not retaining the bottom wall of the stepped groove 160 and not forming a stepped structure. That is, a narrower cutting blade can be used for secondary cutting, with the cutting path positioned corresponding to the sidewall of the stepped groove 160, allowing cutting along the sidewall of the stepped groove 160 while retaining the structural groove 117, and cutting the packaging structure 100 into individual products to complete the process. Of course, the structural groove 117 can also be omitted, and the cutting path can be aligned with the sidewall of the stepped groove 160, still resulting in a single product.

[0165] See Figure 17 and Figure 18This invention also provides a packaging structure 100, which is fabricated using the aforementioned lead frame 110 packaging method. The packaging structure 100 includes a lead frame 110, a chip 140, and a back gold layer 170. The lead frame 110 includes a base island 112 and a plurality of pins 113. The plurality of pins 113 are hollowed out and disposed on at least two sides of the base island 112, and a stepped groove 160 is formed on the back side of each pin 113. The chip 140 is mounted on the front side of the base island 112 and electrically connected to the pins 113. The back gold layer 170 is electroplated and formed on the back sides of the pins 113 and the base island 112, extending to the sidewall of the stepped groove 160. Further, a stepped groove 160 is formed on the back side of each pin 113, and the back gold layer 170 extends to the sidewall of the stepped groove 160. Specifically, a structural groove 117 is also formed on the back of the pin 113. The structural groove 117 is connected to the stepped groove 160. The structural groove 117 can be formed by laser drilling. The bottom wall of the stepped groove 160 can serve as a stop layer, thereby improving the welding performance.

[0166] See Figure 19 In other preferred embodiments of the present invention, a structural groove 117 is also formed on the back side of the pin 113. The structural groove 117 extends to the edge sidewall of the pin 113. Specifically, the structural groove 117 can be formed on the pin 113 by a laser drilling structure, thereby forming a dimple structure.

[0167] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method of leadframe packaging, characterized by, The method comprises the following steps: providing a lead frame, wherein the lead frame comprises a connecting skeleton and a plurality of pins, the connecting skeleton is provided with a mounting window, and the plurality of pins are hollowed out on at least two sides of the mounting window and connected to the connecting skeleton; cutting accommodation grooves on the front surface of the plurality of pins, wherein the accommodation grooves are located at one end of the pins close to the connecting skeleton; attaching a conductive ring to the plurality of accommodation grooves on the front surface of the pins to electrically connect the plurality of pins through the conductive ring, wherein the conductive ring is further provided with a plurality of support portions, and each support portion is embedded between two adjacent pins; forming a back adhesive layer on the back surface of the connecting skeleton, wherein the back adhesive layer extends and covers the plurality of support portions and the plurality of pins; attaching a chip to the lead frame, wherein the chip is electrically connected to the pins; forming a plastic encapsulation layer on the front surface of the connecting skeleton, wherein the plastic encapsulation layer fills the gaps between the plurality of pins and covers the chip, the conductive ring and the plurality of pins; removing the back adhesive layer to expose the back surface of the pins and the connecting skeleton; removing the back surface of the pins to form a stepped groove exposing the conductive ring; forming a back gold layer on the back surface of the pins by electroplating; cutting the plastic encapsulation layer and the pins along a cutting path, wherein the cutting path corresponds to the side wall of one side of the accommodation groove close to the mounting window and corresponds to the inner side of the accommodation groove.

2. The leadframe packaging method of claim 1, wherein, The lead frame further comprises an island, the island is arranged in the mounting window, and the plurality of pins are hollowed out on at least two sides of the island; the step of attaching the chip to the lead frame comprises: attaching the back surface of the chip to the front surface of the island; forming a plurality of connection line arcs on the front surface of the chip by wire bonding, wherein the plurality of connection line arcs are connected to the plurality of pins.

3. The leadframe packaging method of claim 2, wherein, The lead frame further comprises a connecting rod, the connecting rod is arranged around the island and connected to the connecting skeleton; before the step of attaching the conductive ring to the plurality of accommodation grooves on the front surface of the pins, the method further comprises: cutting a avoiding groove on the front surface of the connecting rod, wherein the avoiding groove is used to accommodate the conductive ring.

4. The leadframe packaging method of claim 3, wherein, The conductive ring is in the form of an integral rectangular frame; the step of cutting the accommodation grooves on the front surface of the plurality of pins comprises: cutting the accommodation grooves on the plurality of pins on the same side of the island in the same straight line direction, wherein each accommodation groove penetrates the pins in the horizontal direction and is used to accommodate the conductive ring.

5. The method of claim 3, wherein, The conductive ring comprises a plurality of sub-conductive members arranged in a frame; the step of cutting the accommodation grooves on the front surface of the plurality of pins comprises: cutting the accommodation grooves on the plurality of pins on the same side of the island in the same straight line direction, wherein the front surface of each pin is cut to form two accommodation grooves spaced apart, and each accommodation groove is used to accommodate the end portion of the sub-conductive member.

6. The leadframe packaging method of claim 5, wherein, After the step of attaching the conductive ring to the front surface of the plurality of pins in the plurality of accommodation grooves, the method further comprises: forming a structure line arc by wire bonding between adjacent pins, wherein two ends of each structure line arc are respectively connected to the middle portions of two adjacent pins, so that the structure line arc is arranged in an arc shape on the corresponding sub-conductive member.

7. The leadframe packaging method of claim 3, wherein, Before the step of cutting the avoidance groove on the front surface of the connecting rod, the method further comprises: thinning the front surface of the plurality of pins, so that the height of the pins relative to the back surface of the connecting skeleton is less than the height of the connecting rod relative to the back surface of the connecting skeleton.

8. The leadframe packaging method of claim 1, wherein, Before the step of attaching the conductive ring to the front surface of the plurality of pins in the plurality of accommodation grooves, the method further comprises: forming a plurality of support portions on the conductive ring, the support portions being used to be embedded between two adjacent pins; forming a support groove on the plurality of support portions, wherein the support groove is used to accommodate the back adhesive layer; wherein the extension direction of the support groove is consistent with the extension direction of the accommodation groove.

9. The leadframe packaging method of claim 1, wherein, The step of attaching the conductive ring to the front surface of the plurality of pins in the plurality of accommodation grooves comprises: forming a conductive adhesive layer in the plurality of accommodation grooves; attaching the conductive ring to the plurality of accommodation grooves correspondingly, so that the conductive ring is fixedly bonded in the accommodation grooves through the conductive adhesive layer.

10. The method of claim 1, wherein The step of removing the partial area of the back surface of the pin comprises: forming a protective layer on the back surface of the pin; forming an etching opening on the protective layer; etching the back surface of the pin along the etching opening to form a step groove exposing the conductive ring.

11. The leadframe packaging method of claim 1, wherein, The step of removing the partial area of the back surface of the pin comprises: cutting to remove the partial area of the back surface of the pin to form a step groove exposing the conductive ring.

12. A package structure prepared by the lead frame packaging method according to claim 1, characterized in that, The packaging structure comprises: a lead frame comprising a plurality of pins; a chip attached to the lead frame and electrically connected to the plurality of pins; a plastic encapsulation layer covering the lead frame and the chip, and the back surface of the plurality of pins is exposed to the plastic encapsulation layer; a back gold layer formed by electroplating on the back surface of the pin.

13. The package structure of claim 12, wherein, The lead frame further comprises a base island, the plurality of pins are distributed on at least two sides of the base island, the chip is attached to the front surface of the base island, the plastic encapsulation layer covers the front surface and the side wall of the base island, and the back gold layer is also formed by electroplating on the back surface of the base island.

14. The package structure of claim 12 or 13, wherein, The back surface of each pin is formed with a step groove, and the back gold layer extends to the side wall of the step groove.

15. The package structure of claim 14, wherein, The plastic encapsulation layer is protrudingly arranged between two adjacent step grooves.

16. The package structure of claim 14, wherein, The back surface of the pin is further formed with a structure groove, and the structure groove is communicated to the step groove.

17. The package structure of claim 14, wherein, The back surface of the pin is further formed with a structure groove, and the structure groove extends to the edge side wall of the pin.

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