Leadframe packaging method and packaging structure

Abstract

This invention provides a leadframe packaging method and structure, relating to the field of chip packaging technology. First, a leadframe is provided. Then, wire bonding is applied to the front side of each first pseudo-pin to form a first connecting arc, achieving electrical connection between multiple first pseudo-pins and / or multiple connecting pins. Next, an adhesive layer is formed on the back side of the connecting frame, and the chip is mounted on the leadframe. Then, a molding compound is formed on the front side of the connecting frame. The adhesive layer is removed, a stepped groove is formed, and finally, a back gold layer is formed. Compared to existing technologies, this invention improves the adhesive bonding strength of the adhesive layer, effectively reducing the risk of adhesive layer detachment during molding, thereby reducing the risk of back adhesive overflow contamination during molding. Furthermore, it mitigates the skin effect during electroplating, improving electroplating quality and process efficiency, resulting in better electroplating quality and higher process efficiency.

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, the gap between the pins results in relatively poor electrical connection performance. This can easily lead to a skin effect during electroplating, where the current density on the pin surface is too high and the current density inside is too low, thus affecting 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 connecting pins, the connecting skeleton is provided with a mounting window, the plurality of connecting pins are hollowed out and disposed at least on both sides of the mounting window and connected to the connecting skeleton, and a first pseudo-pin connected to the connecting skeleton is also provided between each two adjacent connecting pins.

[0008] A first connection arc is formed by wire bonding on the front side of each first pseudo-pin, wherein the first connection arc is connected to the adjacent first pseudo-pin and / or the connection pin;

[0009] An adhesive layer is formed on the back side of the connecting skeleton, wherein the adhesive layer extends to cover the plurality of first dummy pins and the plurality of connecting pins;

[0010] A chip is mounted on the front side of the lead frame, wherein the chip is electrically connected to a plurality of the connection pins;

[0011] A molding layer is formed on the front side of the connection frame, wherein the molding layer fills the gap between the plurality of connection pins and covers the chip, the first dummy pin and the plurality of connection pins;

[0012] Remove the adhesive backing layer to expose the back of the connection pin, the first dummy pin, and the connection skeleton;

[0013] Remove a portion of the back side of the connection pin to form a stepped groove;

[0014] A back gold layer extending to the sidewall of the stepped groove is formed by electroplating on the back of the connection pin and the base island.

[0015] The molding layer and the connection pin are cut along a cutting path, which corresponds to the first pseudo-pin.

[0016] 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:

[0017] The back of the chip is attached to the front of the base island;

[0018] Multiple connecting arcs are formed on the front side of the chip, and the multiple connecting arcs are connected to the multiple pins respectively.

[0019] In an optional implementation, the step of forming a first connection arc by wire bonding on the front side of each first dummy pin includes:

[0020] A first connection arc is formed on the front side of each first pseudo-pin to connect to the adjacent first pseudo-pin, wherein the first connection arc is distributed in an arch shape on the connection pin between two adjacent first pseudo-pins.

[0021] In an optional implementation, a second pseudo-pin connected to the connecting skeleton is further provided between each pair of adjacent connecting pins. The second pseudo-pin is misaligned with the first pseudo-pin and is disposed on the first pseudo-pin. After the step of forming a first connecting line arc by wiring on the front side of each first pseudo-pin, the method further includes:

[0022] A second connection arc is formed on the front side of each second pseudo-pin by wire bonding, wherein the second connection arc is connected to the adjacent second pseudo-pin and / or the connection pin.

[0023] In an optional implementation, the step of forming a first connection arc by wire bonding on the front side of each first dummy pin includes:

[0024] A first connection arc is formed on the front side of each of the first pseudo-pins, connecting to the adjacent connection pin, wherein the first connection arc is distributed in an arch shape between the connection pin and the first pseudo-pin.

[0025] In an optional embodiment, prior to the step of forming an adhesive layer on the back side of the connecting skeleton, the method further includes:

[0026] An adhesive groove is formed on the back side of each of the first pseudo-pins, wherein the adhesive groove is used to accommodate the adhesive backing layer.

[0027] In an optional embodiment, prior to the step of forming an adhesive layer on the back side of the connecting skeleton, the method further includes:

[0028] A cutting groove is formed on the back of each of the connection pins, wherein the cutting groove and the adhesive groove extend in the same straight line direction, and the depth of the cutting groove is greater than that of the adhesive groove, and the width of the cutting groove is less than that of the adhesive groove.

[0029] In an optional embodiment, prior to the step of forming an adhesive layer on the back side of the connecting skeleton, the method further includes:

[0030] An overflow groove is formed on the back of the connecting frame, wherein the overflow groove is formed around the mounting window.

[0031] In an optional embodiment, after the step of forming an overflow groove by slotting the back side of the connecting frame, the method further includes:

[0032] Drainage strips are attached to at least a portion of the overflow groove to divide the overflow groove into at least two overflow sub-grooves, wherein the extension direction of the drainage strips is the same as the extension direction of the overflow groove.

[0033] In an optional embodiment, prior to the step of attaching a drain strip to at least a portion of the overflow groove, the method further includes:

[0034] A tapered guide hole and a check hole are formed on the side wall of the drainage strip, wherein the guide hole and the check hole are inclined to extend to the opposite side walls of the drainage strip, and the large end of the guide hole and the small end of the check hole are located on the same side wall of the drainage strip.

[0035] In an optional implementation, the step of removing a portion of the back side of the connection pin includes:

[0036] A protective layer is formed on the back side of the pin;

[0037] An etched opening is formed on the protective layer;

[0038] The back side of the pin is etched along the etch opening to form a stepped groove.

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

[0040] A portion of the back side of the pin is cut away to form a stepped groove.

[0041] Secondly, the present invention provides a packaging structure, which is prepared using the aforementioned lead frame packaging method, the packaging structure comprising:

[0042] A lead frame, the lead frame including a plurality of pins;

[0043] A chip, which is mounted on a lead frame and electrically connected to a plurality of said pins;

[0044] A molding compound covers the lead frame and the chip, with the back sides of the plurality of pins exposed outside the molding compound;

[0045] A gold backing layer, which is electroplated and formed on the back side of the pin.

[0046] 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.

[0047] 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.

[0048] In an optional embodiment, the encapsulation layer protrusion is disposed between two adjacent stepped grooves.

[0049] 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.

[0050] 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.

[0051] The beneficial effects of the embodiments of the present invention include:

[0052] The leadframe packaging method and packaging structure provided in this invention first provide a leadframe with a mounting window on its connecting skeleton. Multiple connecting pins are hollowed out and disposed at least on both sides of the mounting window and connected to the connecting skeleton. A first dummy pin, connected to the connecting skeleton, is also provided between every two adjacent connecting pins. Then, a first connecting arc is formed on the front side of each first dummy pin, which can connect to adjacent first dummy pins and / or connecting pins, realizing electrical connection between multiple first dummy pins and / or multiple connecting pins. Next, an adhesive layer is formed on the back side of the connecting skeleton, extending to cover the first dummy pins and connecting pins. The presence of the first dummy pins enhances the adhesive strength of the adhesive layer. Then, chip mounting is performed on the front side of the leadframe. Finally, a molding compound is formed on the front side of the connecting skeleton, filling the gaps between the multiple connecting pins and encapsulating the chip, the first dummy pins, and the connecting pins. Then, the adhesive backing layer is removed, exposing the back of the connecting pins, the first dummy pin, and the connecting skeleton. A portion of the back of the connecting pins and the first dummy pin is then cut away to form a stepped groove. Finally, a gold backing layer extending to the sidewalls of the stepped groove is electroplated on the back of the connecting pins and the base island. Compared to existing technologies, the lead frame packaging method and packaging structure provided in this invention, by setting the first dummy pin, allows the adhesive backing layer to adhere to and cover the first dummy pin, increasing the bonding area and thus improving the adhesive bonding strength. This effectively reduces the risk of adhesive backing layer detachment during molding, thereby reducing the risk of back adhesive overflow contamination during molding. Furthermore, the first connecting arc is used during electroplating to achieve electrical connection between the first dummy pins or between the connecting pins, increasing the internal current density. This allows multiple pins to be directly electrically connected during electroplating, mitigating the skin effect, improving electroplating quality, and increasing process efficiency. The resulting electroplating quality is better, and the process efficiency is higher. Attached Figure Description

[0053] 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.

[0054] Figure 1 This is a flowchart illustrating the steps of the lead frame packaging method provided in the first embodiment of the present invention.

[0055] Figure 2a This is a front view of step S1 in the lead frame packaging method provided in the first embodiment of the present invention.

[0056] Figure 2b and Figure 2c This is a partial schematic diagram of step S1 in the lead frame encapsulation method provided in the first embodiment of the present invention from different perspectives.

[0057] Figure 3a , Figure 3b and Figure 3c This is a partial schematic diagram of step S2 in the lead frame encapsulation method provided in the first embodiment of the present invention from different perspectives.

[0058] Figure 4a and Figure 4b This is a partial schematic diagram of step S3 in the lead frame encapsulation method provided in the first embodiment of the present invention from different perspectives.

[0059] Figure 4c and Figure 4d This is a schematic diagram corresponding to the step of preparing the cutting groove and the bonding groove before step S3 in the lead frame packaging method provided in the first embodiment of the present invention.

[0060] Figure 5a and Figure 5b This is a partial schematic diagram of step S4 in the lead frame encapsulation method provided in the first embodiment of the present invention from different perspectives.

[0061] Figure 6a and Figure 6b This is a partial schematic diagram of step S5 in the lead frame encapsulation method provided in the first embodiment of the present invention, taken from different perspectives.

[0062] Figure 7a and Figure 7b This is a partial schematic diagram of step S6 in the lead frame encapsulation method provided in the first embodiment of the present invention from different perspectives.

[0063] Figure 8aThis is a cross-sectional schematic diagram of the first process in step S7 of the lead frame packaging method provided in the first embodiment of the present invention.

[0064] Figure 8b This is a cross-sectional schematic diagram of the second process in step S7 of the lead frame packaging method provided in the first embodiment of the present invention.

[0065] Figure 9 This is a partial schematic diagram of step S8 in the lead frame encapsulation method provided in the first embodiment of the present invention.

[0066] Figure 10a and Figure 10b Local schematic diagrams of the steps for preparing the overflow groove before step S8 from different perspectives;

[0067] Figure 11a This is a schematic diagram corresponding to step S9 in the lead frame packaging method provided in the first embodiment of the present invention;

[0068] Figure 11b , Figure 11c , Figure 11d , Figure 11e , Figure 11f , Figure 11g This is a schematic diagram of different products obtained in step S9 of the lead frame packaging method provided in the first embodiment of the present invention.

[0069] Figure 12 A schematic diagram of the packaging structure provided in the first embodiment of the present invention;

[0070] Figure 13 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;

[0071] Figure 14 This is a partial schematic diagram of step S1 in the lead frame packaging method provided in the third embodiment of the present invention;

[0072] Figure 15 This is a partial schematic diagram corresponding to step S2 in the lead frame packaging method provided in the third embodiment of the present invention.

[0073] Icons: 100 - Package structure; 110 - Lead frame; 111 - Connecting skeleton; 112 - Base island; 113 - Connecting pin; 114 - Cutting groove; 115 - Structural groove; 116 - Connecting rod; 120 - First pseudo-pin; 121 - First connecting line arc; 122 - Adhesive groove; 130 - Backing layer; 140 - Chip; 141 - Structural line arc; 150 - Molding layer; 160 - Step groove; 161 - Protective layer; 170 - Backing gold layer; 180 - Overflow groove; 181 - Drain bar; 182 - Drain hole; 183 - Check hole; 190 - Second pseudo-pin; 191 - Second connecting line arc. Detailed Implementation

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] Furthermore, the terms "first" and "second" are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] First Embodiment

[0083] See Figure 1 This invention provides a lead frame 110 packaging method for preparing a packaging structure 100, which can reduce the risk of backside adhesive overflow during molding, and also improve electroplating quality and process efficiency.

[0084] The lead frame 110-frame packaging method provided in this embodiment of the invention includes the following steps:

[0085] S1: Provide a lead frame 110.

[0086] See Figure 2a , Figure 2b and Figure 2cThe lead frame 110 includes a connecting frame 111, a base island 112, and multiple connecting pins 113. The connecting frame 111 has mounting windows, and the base island 112 is disposed within these windows. Connecting rods 116 are arranged around the base island 112, connecting to the connecting frame 111. Multiple connecting pins 113 are hollowed out and disposed on at least two sides of the base island 112, connecting to the connecting frame 111. A first pseudo-pin 120, connected to the connecting frame 111, is also provided between each pair of adjacent connecting pins 113. It should be noted that the lead frame 110 can have multiple rectangularly distributed mounting windows, each containing the base island 112 and multiple pins. These pins can be distributed around the base island 112, facilitating the subsequent formation of a QFN package structure 100. Alternatively, the pins 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 around the base island 112 as an example.

[0087] It should be noted that during step S1, the lead frame 110 needs to be fabricated. Using conventional lead frame 110 fabrication processes, structures such as the base island 112, connecting pin 113, and first pseudo-pin 120 are formed. The fabrication process of the first pseudo-pin 120 is the same as that of the connecting pin 113, and both the first pseudo-pin 120 and the connecting pin 113 are connected to the connecting frame 111. The protrusion length of the first pseudo-pin 120 is less than the protrusion length of the connecting pin 113.

[0088] S2: A first connecting arc 121 is formed by bonding wires to the front side of each first pseudo-pin 120.

[0089] See Figure 3a , Figure 3b and Figure 3c The first connecting arc 121 is connected to an adjacent first pseudo-pin 120 and / or a connecting pin 113. Specifically, the first connecting arc 121 can be connected to an adjacent first pseudo-pin 120, or it can be connected to both an adjacent first pseudo-pin 120 and a connecting pin 113, or the first connecting arc 121 can be connected to an adjacent connecting pin 113. In this embodiment, the first connecting arc 121 is connected to two adjacent first pseudo-pins 120 as an example.

[0090] When actually forming the first connecting arc 121 through wire bonding, a first connecting arc 121 connecting to adjacent first pseudo-pins 120 can be formed on the front side of each first pseudo-pin 120. The first connecting arc 121 is distributed in an arch shape on the connecting pin 113 between two adjacent first pseudo-pins 120. Multiple first connecting arcs 121 can form a fence structure, which on the one hand allows multiple first pseudo-pins 120 to be connected as a whole, increasing the current density during subsequent electroplating and thus improving the electroplating effect. In particular, it can increase the current flow inside the package structure, improving the internal current density and electrical connection performance, thereby mitigating the skin effect and improving the electroplating effect. On the other hand, it can reduce mold flow impact during molding, further preventing the adhesive film from peeling off due to mold flow impact.

[0091] S3: An adhesive backing layer 130 is formed on the back side of the connecting skeleton 111.

[0092] See Figure 4a and Figure 4b The adhesive layer 130 extends to cover the base island 112, multiple first dummy pins 120, and multiple connection pins 113. Specifically, an adhesive film can be applied to the back of the connecting frame 111 using a film laminating machine. This adhesive film ensures that the back of the connection pins 113 is not encapsulated during molding, and also provides support during the wire bonding process of the chip 140. The adhesive film can simultaneously cover the back of the base island 112 and the multiple connection pins 113, and also cover the first dummy pins 120. By setting the first dummy pins 120, the adhesion of the adhesive film can be further improved, resulting in better bonding and fixation of the adhesive film.

[0093] See Figure 4c and Figure 4d Furthermore, before performing step S3, an adhesive groove 122 can be formed on the back of each first dummy pin 120 by laser grooving or mechanical grooving, wherein the adhesive groove 122 is used to accommodate the adhesive layer 130. Specifically, the adhesive layer 130 can cover the adhesive groove 122 on the back of the first dummy pin 120. By setting the adhesive groove 122, the bonding force between the adhesive layer 130 and the first dummy pin 120 can be further improved, thereby further improving the bonding and fixing effect of the adhesive layer 130.

[0094] It is worth noting that after the adhesive groove 122 is formed by slotting, and before the adhesive backing layer 130 is formed, a cutting groove 114 can also be formed on the back of each connecting pin 113. The cutting groove 114 extends along the same straight line as the adhesive groove 122, and the depth of the cutting groove 114 is greater than that of the adhesive groove 122, while the width of the cutting groove 114 is smaller than that of the adhesive groove 122. Specifically, the cutting groove 114 is relatively narrower and deeper, while the adhesive groove 122 is relatively wider and shallower. Both the adhesive groove 122 and the cutting groove 114 can contact the adhesive backing layer 130, thereby improving the adhesive bonding force of the adhesive backing layer 130. Simultaneously, they can also improve the fluidity of the electroplating solution during the subsequent electroplating process.

[0095] It should be noted that the order of preparation of the adhesive groove 122 and the cutting groove 114 is not limited, as long as they are completed before the adhesive backing layer 130 is applied.

[0096] S4: Attach chip 140 to lead frame 110, wherein chip 140 is electrically connected to a plurality of connection pins 113.

[0097] 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 structural arcs 141 are formed on the front side of chip 140, and each of the multiple structural arcs 141 can be connected to multiple connection pins 113. In this embodiment, wire bonding can be used to form connection arcs around all four sides of chip 140, thereby forming a QFN structure. When using a DFN structure, connection arcs can be formed only on the two edges of the front side of chip 140.

[0098] 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 connecting pins 113 by flip-chip process, thus realizing the electrical connection between the chip 140 and multiple connecting pins 113.

[0099] S5: A molding layer 150 is formed on the front side of the connecting skeleton 111.

[0100] See Figure 6a and Figure 6bThe molding compound 150 fills the gaps between multiple connection pins 113 and covers the base island 112, chip 140, first dummy pin 120, and multiple connection pins 113. Specifically, using a molding process, molding liquid is filled and pressure injection is performed to fill the pin gaps and protect the chip 140 structure to form the molding compound 150. Since the adhesive bonding force of the backing layer 130 is enhanced by the adhesive groove 122 on the first dummy pin 120 and the cutting groove 114 on the connection pins 113, the mold flow impact generated during molding will not cause the adhesive layer 130 to fail, avoiding the situation where the backing layer 130 falls off and forms gaps, resulting in molding compound overflow contamination.

[0101] S6: Remove the adhesive backing layer 130 to expose the back of the connection pin 113, the first dummy pin 120 and the connection skeleton 111.

[0102] See Figure 7a and Figure 7b Specifically, the adhesive backing layer 130 can be removed using a film peeling machine, thereby exposing the back of the connecting pin 113, the base island 112 and the connecting skeleton 111, and exposing the first dummy pin 120 and the adhesive groove 122.

[0103] S7: Remove a portion of the back side of the connection pin 113 to form a stepped groove 160.

[0104] See Figure 8a The stepped groove can be formed using an etching process. Specifically, firstly, a protective layer 161 is formed on the back of the connecting pin 113. This protective layer 161 can be photoresist and simultaneously covers the entire back of the lead frame 110. Then, an etching opening is formed on the protective layer 161, exposing a portion of the connecting pin 113. The back of the pin is then etched along the etching opening to form the stepped groove. The depth of the stepped groove 160 is less than the depth of the adhesive groove 122, and the width of the stepped groove 160 is greater than the minimum spacing between the adhesive grooves 122 in two adjacent mounting windows, allowing the stepped groove 160 to expose the adhesive groove 122, thus forming a half-cut state.

[0105] See Figure 8b Of course, in other preferred embodiments of the present invention, a cutting process (using a laser cutter, plasma cutter, or mechanical cutter, etc.) can also be used to complete the first cut of a wider area. After the first cut, a wider cutting blade can be used for local cutting to form a stepped groove 160. The stepped groove 160 needs to extend to the connecting frame 111, and the depth of the stepped groove 160 is less than the depth of the adhesive groove 122. The width of the stepped groove 160 is greater than the minimum distance between the adhesive grooves 122 in two adjacent mounting windows, so that the stepped groove 160 can expose the adhesive groove 122, thereby forming a half-cut state.

[0106] It should be noted that the stepped groove 160 here exposes both the cutting groove 114 and the bonding groove 122, which facilitates subsequent electroplating operations.

[0107] S8: A back gold layer 170 is formed by electroplating on the back of the connection pin 113, extending to the sidewall of the stepped groove 160.

[0108] 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 a conductive plating apparatus, and the positive electrode is coupled to a 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, specifically on the surfaces of the connecting pins 113, the base island 112, the connecting skeleton 111, and the first dummy pins 120 exposed above the encapsulation layer 150, forming a metal layer. At this time, because the first connecting arc 121 electrically connects multiple first dummy pins 120 into one unit, the current density between the multiple first dummy pins 120 during the electroplating process can be increased, thereby increasing the internal current density, reducing the skin effect, and improving the quality of the electroplated metal layer. The back gold layer 170 can be at least one material selected from tin, gold, silver, palladium, and nickel.

[0109] It should be noted that since both the cutting groove 114 and the bonding groove 122 are exposed within the stepped groove 160, an electroplating flow channel can be formed during electroplating. The conductive bonding groove 122 is relatively wide and shallow, allowing the electroplating solution to flow along the flow channel and improving its fluidity. Furthermore, because the cutting groove 114 is relatively narrow and deep, the electroplating solution can fully wet the connecting pin 113, better achieving the formation of an electroplated metal layer on the pin sidewall.

[0110] See Figure 10a and Figure 10b Furthermore, before performing step S8, an overflow groove 180 can be formed by slotting on the back of the connecting frame 111. Specifically, the overflow groove 180 can be formed by laser grooving on the back of the connecting frame 111, and the overflow groove 180 is formed around the mounting window. After forming the overflow groove 180, a guide strip 181 can be attached to at least a portion of the overflow groove 180 to divide the overflow groove 180 into at least two overflow sub-grooves, wherein the extending direction of the guide strip 181 is the same as the extending direction of the overflow groove 180. The preparation of the overflow groove 180 can improve the fluidity of the electroplating solution in the subsequent electroplating process, while the setting of the guide strip 181 can form multiple flow channels, increase the contact area between the electroplating solution and the lead frame 110, further reduce the skin effect, and improve the electroplating efficiency.

[0111] It should be noted that before attaching the drainage strip 181, tapered guide holes 182 and check holes 183 can be formed on the sidewall of the drainage strip 181. Both the guide holes 182 and check holes 183 extend obliquely to opposite sidewalls of the drainage strip 181, with the larger end of the guide hole 182 and the smaller end of the check hole 183 located on the same sidewall of the drainage strip 181. Specifically, both the guide holes 182 and check holes 183 are inclined holes, meaning their opening directions are inclined to the extension direction of the drainage strip 181. The designed inclination angle can be between 30-60°, for example, 30°, 45°, or 60°. Furthermore, both the guide hole 182 and the check hole 183 are tapered holes with relatively large and small ends. The large ends of the guide hole 182 and the check hole 183 are located on both sides of the guide bar 181, and the small ends are also located on both sides of the guide bar 181. Therefore, the guide hole 182 can serve as a flow channel to accelerate the flow of the electroplating solution in the overflow sub-troughs on both sides of the guide bar 181, while the check hole 183 can serve as a blocking channel to prevent liquid backflow. Through the opening design, the flow rate of the electroplating solution in the overflow sub-troughs on both sides can be kept consistent, ensuring electroplating uniformity.

[0112] S9: Cut the molding layer 150 and the connection pin 113 along the cutting path.

[0113] See Figure 11a , Figure 11b and Figure 11c The dicing path corresponds to the first pseudo-pin 120. Specifically, the dicing path corresponds to the dicing groove 114, which can be used as a dicing path positioning mark to make the cutting more precise and prevent cutting deviation. A narrower cutting blade can be used for secondary cutting to retain the metal layer formed on the sidewall of the dicing path within the connecting pin 113, and to retain the sidewall of the stepped groove 160 after cutting. After cutting, a single packaged product can be formed, which can be a QFN product (…). Figure 11b ), or it can be a DFN product ( Figure 11c ).

[0114] See Figure 11d Of course, in other preferred embodiments of the present invention, before electroplating, a structural groove 115 can be cut again on the connecting pin 113 to form a structural groove 115 that can connect to the stepped groove 160, thereby forming a dimple structure after cutting.

[0115] See Figure 11eIn other preferred embodiments of the present invention, the position of the cutting path can be redefined, for example, the cutting path can be aligned with the sidewall of the stepped groove 160. Furthermore, before electroplating, a structural groove 115 can be formed again on the connecting pin 113, which connects to the stepped groove 160, thereby forming a dimple structure after cutting. Specifically, the bottom wall of the stepped groove 160 is not retained after cutting, and no stepped structure is formed. 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, thereby enabling cutting along the sidewall of the stepped groove 160, retaining the structural groove 115, and cutting the package structure 100 into individual products, completing the process.

[0116] See Figure 11f In other preferred embodiments of the present invention, when the stepped groove 160 is formed by etching, only the connection pin 113 can be etched, that is, the opening on the protective layer 161 only exposes the connection 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.

[0117] See Figure 11g In 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 groove and other undercut phenomena on the sidewall, which can further improve the welding bonding force of the connecting pin 113.

[0118] See also Figure 2a , Figure 3a , Figure 4b , Figure 5a , Figure 6a , Figure 10a and Figure 12This invention also provides a packaging structure 100, which is prepared by the aforementioned method, specifically by steps S1-S8. The packaging structure 100 includes a lead frame 110, a first connecting arc 121, an adhesive layer 130, a chip 140, a molding layer 150, and a gold backing layer 170. The lead frame 110 includes a connecting skeleton 111, a base island 112, and multiple connecting pins 113. The connecting skeleton 111 has a mounting window, and the base island 112 is disposed within the mounting window. Multiple connecting pins 113 are hollowed out and disposed on at least two sides of the base island 112, and connected to the connecting skeleton 111. A first dummy pin 120 connected to the connecting skeleton 111 is also provided between each pair of adjacent connecting pins 113. The first connecting arc 121 is formed by wire bonding on the front side of each first dummy pin 120. The first connecting line arc 121 is connected to the adjacent first dummy pin 120 and / or connecting pin 113; the backing layer 130 is formed on the back of the connecting frame 111, wherein the backing layer 130 extends to cover the base island 112, the plurality of first dummy pins 120 and the plurality of connecting pins 113; the chip 140 is mounted on the front of the base island 112 and is electrically connected to the pins; the molding compound 150 is disposed on the front of the connecting frame 111, the molding compound 150 fills the gap between the plurality of pins, and the molding compound 150 covers the base island 112, the chip 140, the first dummy pins 120 and the plurality of connecting pins 113, and a stepped groove 160 extending to the connecting frame 111 is formed on the back of the connecting pins 113; the back gold layer 170 is electroplated and formed on the back of the connecting pins 113 and the base island 112, and the back gold layer 170 extends to the sidewall of the stepped groove 160.

[0119] 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 connecting pins 113 by flip-chip process, thus realizing the electrical connection between the chip 140 and multiple connecting pins 113.

[0120] Furthermore, each of the two ends of the first connecting arc 121 is connected to two adjacent first pseudo pins 120 respectively, and the first connecting arc 121 is distributed in an arch shape on the connecting pin 113 between the two adjacent first pseudo pins 120.

[0121] In this embodiment, an adhesive groove 122 is formed on the back side of each first pseudo-pin 120, which is used to accommodate the adhesive layer 130. Furthermore, a cutting groove 114 is formed on the back side of each connecting pin 113. The cutting groove 114 and the adhesive groove 122 extend in the same straight line direction, and the depth of the cutting groove 114 is greater than that of the adhesive groove 122, while the width of the cutting groove 114 is less than that of the adhesive groove 122.

[0122] Furthermore, an overflow groove 180 is formed on the back of the connecting frame 111, and the overflow groove 180 is located around the mounting window. At least a portion of the overflow groove 180 is fitted with a guide strip 181 to divide the overflow groove 180 into at least two overflow sub-grooves, wherein the extending direction of the guide strip 181 is the same as the extending direction of the overflow groove 180. The sidewall of the guide strip 181 is formed with a tapered guide hole 182 and a check hole 183, wherein the guide hole 182 and the check hole 183 both extend obliquely to opposite sidewalls of the guide strip 181, and the large end of the guide hole 182 and the small end of the check hole 183 are located on the same sidewall of the guide strip 181.

[0123] It should be noted that both the guide hole 182 and the check hole 183 are inclined holes, meaning that the opening direction of both the guide hole 182 and the check hole 183 is inclined to the extension direction of the guide strip 181. The angle of inclination can be between 30-60°, for example, 30°, 45°, or 60°. Furthermore, both the guide hole 182 and the check hole 183 are conical holes with opposing large and small ends. The large ends of the guide hole 182 and the check hole 183 are located on both sides of the guide strip 181, and the small ends are also located on both sides of the guide strip 181. Therefore, the guide hole 182 can serve as a flow channel, accelerating the flow of the electroplating solution in the overflow sub-tanks on both sides of the guide strip 181, while the check hole 183 can serve as a blocking channel, preventing liquid backflow. This opening design ensures that the flow rate of the electroplating solution in the overflow sub-tanks on both sides is consistent during the electroplating process, guaranteeing electroplating uniformity.

[0124] See Figure 11a , Figure 11b and Figure 11c The present invention also provides another packaging structure 100, which is prepared by the method described above, specifically by the steps S1-S9 described above. 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 connection pins 113. The plurality of connection pins 113 are hollowed out and disposed on at least two sides of the base island 112. The chip 140 is mounted on the front side of the base island 112 and electrically connected to the connection pins 113. The back gold layer 170 is electroplated and formed on the back side of the connection pins 113 and the base island 112.

[0125] 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 11b ), or it can be a DFN package structure 100 (such as Figure 11c ).

[0126] Furthermore, a stepped groove 160 is formed on the back side of each connection pin 113, and the back gold layer 170 can extend to the sidewall of the stepped groove 160.

[0127] See Figure 11d Of course, in other preferred embodiments of the present invention, before electroplating, a structural groove 115 can be cut again on the connecting pin 113 to form a structural groove 115 that can connect to the stepped groove 160, thereby forming a dimple structure after cutting. Specifically, a structural groove 115 is also formed on the back side of the connecting pin 113, and the structural groove 115 connects to the stepped groove 160. The structural groove 115 can be formed by laser drilling, and the bottom wall of its stepped groove 160 can serve as a stop layer, thereby improving welding performance.

[0128] See Figure 11e In other preferred embodiments of the present invention, a structural groove 115 is also formed on the back side of the pin, extending to the edge sidewall of the pin. Specifically, the structural groove 115 can be formed on the pin using a laser drilling structure, thereby forming a dimple structure. During fabrication, the position of the cutting path can also be redefined, for example, the cutting path can be aligned with the sidewall of the stepped groove 160. Furthermore, before electroplating, the structural groove 115 can be formed again on the connecting pin 113, which can connect to the stepped groove 160, thereby forming a dimple structure after cutting. Specifically, the bottom wall of the stepped groove 160 is not retained after cutting, and no stepped structure is formed. 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, thereby cutting along the sidewall of the stepped groove 160, retaining the structural groove 115, and cutting the package structure 100 into individual products to complete the process.

[0129] Of course, the structural groove 115 can be omitted here, and the cutting channel can be directly aligned with the side wall of the stepped groove 160, which can also produce a single product.

[0130] 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 lead frame 110 has a mounting window on its connecting skeleton 111, and a base island 112 is disposed within this mounting window. Multiple connecting pins 113 are hollowed out and disposed on at least two sides of the base island 112, and connected to the connecting skeleton 111. Furthermore, a first pseudo-pin 120 connected to the connecting skeleton 111 is provided between every two adjacent connecting pins 113. Then, a first connecting arc 121 is formed on the front side of each first pseudo-pin 120 by wire bonding. The first connecting arc 121 can connect to adjacent first pseudo-pins 120 and / or connecting pins 113, thereby achieving electrical connection between multiple first pseudo-pins 120 and / or multiple connecting 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 first dummy pin 120, and the connecting pin 113. The first dummy pin 120 enhances the adhesive bonding strength of the adhesive layer 130. Next, the chip 140 is mounted on the front side of the base island 112. Then, a molding compound 150 is formed on the front side of the connecting frame 111. The molding compound 150 fills the gaps between the multiple connecting pins 113 and covers the base island 112, the chip 140, the first dummy pin 120, and the connecting pins 113. Then, the adhesive backing layer 130 is removed, exposing the back surfaces of the connecting pin 113, the first dummy pin 120, the base island 112, and the connecting frame 111. A portion of the back surfaces of the connecting pin 113 and the first dummy pin 120 is then cut away, forming a stepped groove 160. Finally, a gold backing layer 170 extending to the sidewalls of the stepped groove 160 is electroplated on the back surfaces of the connecting pin 113 and the base island 112. Compared to existing technologies, the lead frame 110 packaging method and packaging structure 100 provided in this embodiment of the invention, by setting the first dummy pin 120, allows the adhesive backing layer 130 to adhere to and cover the first dummy pin 120, increasing the bonding area and thus improving the adhesive bonding strength of the adhesive backing layer 130. This effectively reduces the risk of the adhesive backing layer 130 detaching during the molding process, thereby reducing the risk of back adhesive overflow contamination during molding. Furthermore, during electroplating, the first connecting arc 121 is used to achieve electrical connection between the first pseudo pins 120 or between the connecting pins 113, which improves the internal current density and electrical connection performance. During the electroplating process, multiple pins are directly electrically connected to each other, which reduces the current skin effect, improves the electroplating quality, and improves the process efficiency. The electroplating quality is better and the process efficiency is higher.

[0131] Second Embodiment

[0132] This invention provides a lead frame 110-frame packaging method, whose basic steps, principles, and resulting technical effects 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 S2.

[0133] The lead frame 110-frame packaging method provided in this embodiment of the invention includes the following steps:

[0134] S1: Provide a lead frame 110.

[0135] The lead frame 110 provided in step S1 is the same as that in the first embodiment.

[0136] S2: A first connecting arc 121 is formed by bonding wires to the front side of each first pseudo-pin 120.

[0137] See Figure 13 The first connecting arc 121 connects to the adjacent connecting pin 113. Specifically, when forming the first connecting arc 121, wires can be wired onto the front side of each first pseudo-pin 120 to form a first connecting arc 121 connecting to the adjacent connecting pin 113. The first connecting arc 121 is arched and distributed between the connecting pin 113 and the first pseudo-pin 120. Specifically, two first connecting arcs 121 can be wired onto the front side of each first pseudo-pin 120, thereby connecting to the connecting pins 113 on both sides respectively, thus electrically connecting the multiple connecting pins 113 and the multiple first pseudo-pins 120 into a single structure.

[0138] When actually forming the first connecting arc 121 through wire bonding, a first connecting arc 121 connecting to the adjacent connecting pin 113 can be formed on the front side of each first pseudo-pin 120. The first connecting arc 121 is distributed in an arch shape above the gap between the adjacent first pseudo-pins 120 and the connecting pins 113. Multiple first connecting arcs 121 can form a fence structure, which on the one hand allows multiple first pseudo-pins 120 and multiple connecting pins 113 to be connected as one, increasing the current density during subsequent electroplating and thus improving the electroplating effect; on the other hand, it can reduce the impact of mold flow during molding and further prevent the adhesive film from falling off due to the impact of mold flow.

[0139] For details of steps S3-S9, please refer to the first embodiment.

[0140] This invention also provides a packaging structure 100, which is fabricated using the aforementioned method. The packaging structure 100 includes a lead frame 110, a first connecting arc 121, an adhesive layer 130, a chip 140, a molding layer 150, and a back gold layer 170. The lead frame 110 includes a connecting skeleton 111, a base island 112, and multiple connecting pins 113. The connecting skeleton 111 has a mounting window, and the base island 112 is disposed within the mounting window. Multiple connecting pins 113 are hollowed out and disposed on at least two sides of the base island 112, and connected to the connecting skeleton 111. A first dummy pin 120 connected to the connecting skeleton 111 is also provided between each pair of adjacent connecting pins 113. The first connecting arc 121 is formed by wire bonding on the front side of each first dummy pin 120, wherein the first connecting arc 121 connects to adjacent first dummy pins 120 and / or connects to... Pin 113; an adhesive layer 130 is formed on the back side of the connecting frame 111, wherein the adhesive layer 130 extends to cover the base island 112, a plurality of first dummy pins 120 and a plurality of connecting pins 113; a chip 140 is mounted on the front side of the base island 112 and is electrically connected to the pins; a molding compound 150 is disposed on the front side of the connecting frame 111, the molding compound 150 fills the gap between the plurality of pins, and the molding compound 150 covers the base island 112, the chip 140, the first dummy pins 120 and the plurality of connecting pins 113, and a stepped groove 160 extending to the connecting frame 111 is formed on the back side of the connecting pins 113; a back gold layer 170 is electroplated and formed on the back side of the connecting pins 113 and the base island 112, and the back gold layer 170 extends to the sidewall of the stepped groove 160.

[0141] Furthermore, each of the two ends of the first connecting arc 121 is connected to the adjacent connecting pin 113 and the first pseudo pin 120 respectively, and the first connecting arc 121 is distributed in an arch shape between the connecting pin 113 and the first pseudo pin 120.

[0142] In summary, the lead frame 110 frame packaging method and packaging structure 100 provided in this embodiment of the invention connect the first connecting arc 121 to the adjacent first pseudo pin 120 and connecting pin 113, thereby connecting multiple first pseudo pins 120 and multiple connecting pins 113 into one unit, thereby improving the overall electrical connection performance. When electroplating to form the back gold layer 170, it can further increase the current density, reduce the skin effect, and improve the electroplating effect.

[0143] Third Embodiment

[0144] This invention provides a lead frame 110-frame packaging method, whose basic structure, principle and technical effects 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.

[0145] The lead frame 110-frame packaging method provided in this embodiment of the invention includes the following steps:

[0146] S1: Provide a lead frame 110.

[0147] See Figure 14 The lead frame 110 provided in step S1 differs from that in the first embodiment. The lead frame 110 includes a connecting skeleton 111, a base island 112, and multiple connecting pins 113. The connecting skeleton 111 has an installation window, the base island 112 is located within the installation window, and the multiple connecting pins 113 are hollowed out and located on at least two sides of the base island 112, connected to the connecting skeleton 111. A first pseudo-pin 120 connected to the connecting skeleton 111 is also provided between every two adjacent connecting pins 113. A second pseudo-pin 190 connected to the connecting skeleton 111 is also provided between every two adjacent connecting pins 113. The second pseudo-pin 190 is misaligned with the first pseudo-pin 120 and is located on the first pseudo-pin 120. The misalignment of the second pseudo-pin 190 with the first pseudo-pin 120 means that the edges of the second pseudo-pin 190 are not aligned with the edges of the first pseudo-pin 120. Preferably, the second pseudo-pin 190 is located in the middle of the first pseudo-pin 120, thus forming a stepped structure on both sides for easy wire bonding.

[0148] Furthermore, a groove structure can also be formed at the bottom of the second pseudo-pin 190, which can improve the bonding force between the molding layer and the connecting skeleton 111 during molding and increase the structural strength.

[0149] S2: A first connecting arc 121 is formed by bonding wires to the front side of each first pseudo-pin 120.

[0150] See Figure 15 Specifically, the first connecting arc 121 can be connected to the adjacent first pseudo pin 120. When actually forming the first connecting arc 121 by wire bonding, the first connecting arc 121 connected to the adjacent first pseudo pin 120 can be formed by wire bonding on the front side of each first pseudo pin 120. The first connecting arc 121 is distributed in an arch shape on the connecting pin 113 between two adjacent first pseudo pins 120.

[0151] After the first connecting arc 121 is wired, a second connecting arc 191 can be formed on the front side of each second pseudo-pin 190, wherein the second connecting arc 191 connects to adjacent second pseudo-pins 190 and / or connecting pins 113. The second connecting arc 191 can connect to an adjacent second pseudo-pin 190, or to an adjacent connecting pin 113, or to both an adjacent connecting pin 113 and a second pseudo-pin 190. Preferably, the second connecting arc 191 can connect to two adjacent second pseudo-pins 190.

[0152] For details of steps S3-S9, please refer to the first embodiment.

[0153] It should be noted that by setting the second connecting arc 191, the second pseudo-pin 190 can be connected, forming arcs of different heights with the first connecting arc 121, further enhancing the bonding force between the lead frame 110 and the molding layer 150, and improving the overall structural strength. Simultaneously, the staggered design of the first pseudo-pin 120 and the second pseudo-pin 190 also forms a stepped structure, which can further enhance the bonding force of the molding compound, thereby improving the overall structural strength. Furthermore, the first connecting arc 121 and the second connecting arc 191 can further improve the internal conductivity and current density, thereby improving the electroplating effect. Multiple first connecting arcs 121 and multiple second connecting arcs 191 can form a denser fence structure, which can better buffer the impact of the mold flow.

[0154] The present invention also provides a packaging structure 100, which is prepared by the aforementioned method. The packaging structure 100 includes a lead frame 110, a first connecting arc 121, an adhesive layer 130, a chip 140, a molding layer 150, and a back gold layer 170. The lead frame 110 includes a connecting skeleton 111, a base island 112, and a plurality of connecting pins 113. The connecting skeleton 111 has a mounting window, and the base island 112 is disposed within the mounting window. The plurality of connecting pins 113 are hollowed out and disposed on at least two sides of the base island 112 and connected to the connecting skeleton 111. A first dummy pin 120 connected to the connecting skeleton 111 is also provided between each two adjacent connecting pins 113. The first connecting arc 121 is formed by wire bonding on the front side of each first dummy pin 120, wherein the first connecting arc 121 is connected to adjacent first dummy pins 120 and / or connected to... Pin 113; an adhesive layer 130 is formed on the back side of the connecting frame 111, wherein the adhesive layer 130 extends to cover the base island 112, a plurality of first dummy pins 120 and a plurality of connecting pins 113; a chip 140 is mounted on the front side of the base island 112 and is electrically connected to the pins; a molding compound 150 is disposed on the front side of the connecting frame 111, the molding compound 150 fills the gap between the plurality of pins, and the molding compound 150 covers the base island 112, the chip 140, the first dummy pins 120 and the plurality of connecting pins 113, and a stepped groove 160 extending to the connecting frame 111 is formed on the back side of the connecting pins 113; a back gold layer 170 is electroplated and formed on the back side of the connecting pins 113 and the base island 112, and the back gold layer 170 extends to the sidewall of the stepped groove 160.

[0155] Furthermore, a second pseudo-pin 190 connected to the connecting frame 111 is provided between every two adjacent connecting pins 113. The second pseudo-pin 190 is staggered with the first pseudo-pin 120 and is disposed on the first pseudo-pin 120. A second connecting arc 191 is formed on the front side of each second pseudo-pin 190, wherein the second connecting arc 191 is connected to the adjacent second pseudo-pin 190 and / or connecting pin 113. Preferably, the two ends of the second connecting arc 191 are respectively connected to the adjacent second pseudo-pins 190, so that the second connecting arc 191 can be distributed in an arch shape on the first connecting arc 121.

[0156] In summary, this invention provides a leadframe 110 frame packaging method and a packaging structure 100. By setting a second connecting arc 191, the second pseudo-pin 190 can be connected, forming arcs of different heights with the first connecting arc 121, further enhancing the bonding force between the leadframe 110 and the molding layer 150, and improving the overall structural strength. Simultaneously, the staggered design of the first pseudo-pin 120 and the second pseudo-pin 190 can also form a stepped structure, which can also improve the bonding force of the molding compound, thereby enhancing the overall structural strength. Furthermore, the first connecting arc 121 and the second connecting arc 191 can further improve the internal conductivity and current density, thereby improving the electroplating effect. Multiple first connecting arcs 121 and multiple second connecting arcs 191 can form a denser fence structure, which can better buffer the impact of mold flow.

[0157] 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 connecting pins, the connecting skeleton is provided with a mounting window, a plurality of the connecting pins are hollowly arranged on at least two side edges of the mounting window and connected to the connecting skeleton, and a first dummy pin connected to the connecting skeleton is further arranged between every two adjacent connecting pins; forming a first connecting line arc on the front surface of each first dummy pin by wire bonding, wherein the first connecting line arc is connected to adjacent first dummy pins and / or connecting pins; forming a back adhesive layer on the back surface of the connecting skeleton, wherein the back adhesive layer extends and covers a plurality of the first dummy pins and a plurality of the connecting pins; attaching a chip on the front surface of the lead frame, wherein the chip is electrically connected to a plurality of the connecting pins; forming a plastic encapsulation layer on the front surface of the connecting skeleton, wherein the plastic encapsulation layer fills the gaps between a plurality of the connecting pins and covers the chip, the first dummy pins and a plurality of the connecting pins; removing the back adhesive layer to expose the back surface of the connecting pins, the first dummy pins and the connecting skeleton; removing the back surface of the connecting pins in a partial region to form a stepped groove; forming a back gold layer on the back surface of the connecting pins by electroplating, wherein the back gold layer extends to the sidewall of the stepped groove; cutting the plastic encapsulation layer and the connecting pins along a cutting path, wherein the cutting path extends along the connecting direction of a plurality of the first dummy pins on the same side edge.

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

3. The leadframe packaging method of claim 2, wherein, The step of forming a first connecting line arc on the front surface of each first dummy pin comprises: forming a first connecting line arc on the front surface of each first dummy pin by wire bonding, wherein the first connecting line arc is connected to adjacent first dummy pins, and the first connecting line arc is arched and distributed above the connecting pins between adjacent first dummy pins.

4. The leadframe packaging method according to claim 2 or 3, wherein, A second dummy pin connected to the connecting skeleton is further arranged between every two adjacent connecting pins, the second dummy pin is staggered with the first dummy pin and arranged on the first dummy pin, and after the step of forming a first connecting line arc on the front surface of each first dummy pin, the method further comprises: forming a second connecting line arc on the front surface of each second dummy pin by wire bonding, wherein the second connecting line arc is connected to adjacent second dummy pins and / or connecting pins.

5. The leadframe packaging method of claim 2, wherein, The step of forming a first connecting line arc on the front surface of each first dummy pin comprises: forming a first connecting line arc on the front surface of each first dummy pin by wire bonding, wherein the first connecting line arc is connected to adjacent connecting pins, and the first connecting line arc is arched and distributed between the connecting pins and the first dummy pin.

6. The leadframe packaging method of claim 2, wherein, Before the step of forming a back adhesive layer on the back surface of the connecting skeleton, the method further comprises: A groove is formed on the back of each of the first pins to form an adhesive groove, wherein the adhesive groove is used to accommodate the adhesive layer.

7. The leadframe packaging method of claim 6, wherein, Before the step of forming the adhesive layer on the back of the connecting skeleton, the method further comprises: A groove is formed on the back of each of the connecting pins to form a cutting groove, wherein the cutting groove extends in the same direction as the adhesive groove, and the depth of the cutting groove is greater than that of the adhesive groove, and the width of the cutting groove is less than that of the adhesive groove.

8. The leadframe packaging method of claim 2, wherein, Before the step of forming the adhesive layer on the back of the connecting skeleton, the method further comprises: A groove is formed on the back of the connecting skeleton to form an overflow groove, wherein the overflow groove is formed around the mounting window.

9. The method of claim 8, wherein, After the step of forming the overflow groove on the back of the connecting skeleton, the method further comprises: A drainage strip is attached to at least part of the overflow groove to divide the overflow groove into at least two overflow sub-channels, wherein the extension direction of the drainage strip is the same as that of the overflow groove.

10. The method of claim 9, wherein, Before the step of attaching the drainage strip to at least part of the overflow groove, the method further comprises: A tapered flow guide hole and a check hole are formed on the side wall of the drainage strip, wherein the flow guide hole and the check hole are inclined through to the opposite side walls of the drainage strip, and the large hole end of the flow guide hole and the small hole end of the check hole are located on the same side wall of the drainage strip.

11. The leadframe packaging method of claim 1, wherein, The step of removing part of the back of the connecting pin comprises: A protective layer is formed on the back of the pin; An etching opening is formed on the protective layer; The back of the pin is etched along the etching opening to form a stepped groove.

12. The method of claim 1, wherein, The step of removing part of the back of the pin comprises: The back of the pin is cut to remove part of the back to form a stepped groove.

13. A package structure prepared by the lead frame packaging method according to claim 1, characterized in that, The package 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 of the plurality of pins exposed outside the plastic encapsulation layer; A back gold layer electroplated on the back of the pins.

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

15. The package structure of claim 13 or 14, wherein, The back of each pin forms a stepped groove, and the back gold layer extends to the side wall of the stepped groove.

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

17. The package structure of claim 15, wherein, The back of the pin further forms a structural groove, and the structural groove is connected to the stepped groove.

18. The package structure of claim 15, wherein, The back of the pin further forms a structural groove, and the structural groove extends to the edge side wall of the pin.

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