A lead frame structure suitable for secondary cutting

Abstract

The application provides a lead frame structure suitable for secondary cutting, which comprises a frame web and a pin connected with the frame web, at least one first buffer groove is formed at the position where the frame web is connected with the pin, the depth of the first buffer groove is greater than the depth of the primary cutting path, the first buffer groove is located at the inner side of the secondary cutting path, and the first buffer groove is filled with insulating material, and the adhesion between the insulating material and the electroplated burr is less than the adhesion between the pin and the electroplated burr. By forming the first buffer groove, the subsequent electroplated layer forms a first buffer space at the position of the first buffer groove, which can provide a deformation space for the electroplated layer when the cutting tool cuts the electroplated layer, so as to prevent the deformation of the electroplated layer at the position of the frame web first contacted by the cutting tool from being transmitted to the electroplated layers at the positions of the pins on both sides. The cut electroplated layer is washed away with the cutting water flow and cannot be attached to the insulating material or the pin position, so as to relieve the problem of the electroplated burr generated at the pin position.

Description

Technical Field

[0001] This application relates to the field of semiconductor packaging, and more particularly to a lead frame structure suitable for secondary cutting. Background Technology

[0002] "Wettable Flank" refers to a special packaging design (wettable flank package) primarily used in leadless packages (such as QFN / DFN). This design creates a solderable surface on the side of the package, allowing solder to form a detectable weld along the side of the package during surface mount technology (SMT). This facilitates the use of automated optical inspection (AOI) equipment to check the quality of solder joints, thereby improving production efficiency and product quality. Wettable Flank QFN products undergo two dicing processes during packaging. The first dicing process involves cutting along the base dicing track to form the first dicing track, creating an electroplated layer (e.g., tin plating) at the pins and the corresponding frame ribs within the first dicing track. The second dicing process uses a narrower cutting tool than the first dicing process and continues cutting along the middle of the first dicing track.

[0003] During the secondary cutting process, the electroplated layer formed by electroplating is evenly distributed on the surface of the dambar (frame connecting rib) of the lead frame structure. In addition, the cutting tool will wear after long-term use, resulting in electroplated burrs after the secondary cutting process, which affects product quality. Summary of the Invention

[0004] The problem this application aims to solve is to provide a lead frame structure suitable for secondary cutting, so as to change the electroplated layer structure formed on the surface of the frame connecting ribs of the lead frame structure during secondary cutting, thereby alleviating the problem of tin burrs caused by the wear of the cutting tool during secondary cutting.

[0005] To address the aforementioned problems, this application provides a lead frame structure suitable for secondary cutting, comprising:

[0006] Frame unit, the frame unit including pins;

[0007] Frame connecting bars are provided between adjacent frame units, and the frame connecting bars are connected to the pins of the frame units;

[0008] At least one first buffer groove is formed near the pipe foot of the frame connecting rib. The depth of the first buffer groove is greater than the depth of the corresponding primary cutting channel. The first buffer groove is located inside the corresponding secondary cutting channel. The primary cutting channel is a primary cutting groove formed by a primary cutting process. The secondary cutting channel is a secondary cutting channel formed by a secondary cutting process at the bottom of the primary cutting groove. The width of the primary cutting channel is greater than the width of the corresponding secondary cutting channel, and the secondary cutting channel is located inside the corresponding primary cutting channel.

[0009] The first buffer groove is filled with insulating material, and the adhesion between the insulating material and the electroplated burr is less than the adhesion between the pin and the electroplated burr.

[0010] In actual use, a single cutting process creates a single cutting path. An electroplated layer is formed at the pin and the corresponding frame connecting rib position within the single cutting path. Because the first buffer groove is filled with non-conductive insulating material, an electroplated layer cannot form at the first buffer groove position. That is, the electroplated layer forms a first buffer space at the first buffer groove position. The first buffer space is used to provide space for deformation of the electroplated layer when the cutting tool cuts the packaging structure. When a secondary cutting process is performed on the frame connecting ribs corresponding to the tube feet within the primary cutting channel using a cutting tool, the cutting part of the secondary cutting tool has a pointed conical structure. When the cutting tool contacts the electroplated layer and generates stress and extrusion on the electroplated layer, the deformation of the electroplated layer is interrupted in the first buffer space because the first buffer groove cannot form an electroplated layer. This prevents the deformation of the electroplated layer at the frame connecting ribs first contacted by the cutting tool from being transmitted to the electroplated layers at the tube feet on both sides. At the same time, since the adhesion force between the insulating material and the electroplated burrs is less than that between the tube feet and the electroplated burrs, the electroplated layer squeezed in the first buffer space on the surface of the insulating material is washed away by the cutting water flow and will not adhere to the insulating material or the tube feet. This alleviates the problem of electroplated burrs at the tube feet and improves product quality.

[0011] In actual use, the secondary cutting process forms a secondary cutting channel. The width of the secondary cutting channel is smaller than the width of the corresponding primary cutting channel. Since the first buffer groove is located inside the corresponding secondary cutting channel, the first buffer groove is cut off during the secondary cutting process to ensure the flatness and appearance integrity of the product.

[0012] In one optional embodiment, the frame connecting bar includes a connecting bar body and a connecting support bar, the tube feet are located on both sides of the connecting bar body, and the tube feet are connected to the connecting bar body through the connecting support bar;

[0013] The first buffer groove is located inside the connecting support bar.

[0014] In one optional embodiment, the frame connecting bar includes a connecting bar body and a connecting support bar, the tube feet are located on both sides of the connecting bar body, and the tube feet are connected to the connecting bar body through the connecting support bar;

[0015] The first buffer groove is located on the connecting rib body and is close to the connecting support ribs on both sides.

[0016] In an optional embodiment, the frame connecting rib is directly connected to the tube foot, and the first buffer groove is located on the frame connecting rib and close to the tube foot on both sides.

[0017] The frame connecting ribs are provided with a first buffer groove on each side near the tube feet, which can form two first buffer spaces in the electroplated layer. The two first buffer spaces are located on both sides of the frame connecting ribs where the electroplated layer is first contacted by the cutting tool, which can alleviate the problem of electroplating burrs at the tube feet on both sides and further improve product quality.

[0018] In one optional embodiment, the frame connecting rib is a semi-etched rib, the frame connecting rib has a basic cutting channel, the depth of the basic cutting channel is less than or equal to the depth of the corresponding primary cutting channel.

[0019] In practical applications, the basic etch marks are formed through a semi-etching process. These marks provide a clear path for the cutting tool, reducing cutting resistance and tool wear, and improving cutting efficiency and precision. Simultaneously, the basic etch marks can also form connections between lead frame units, ensuring the stability of the frame structure during cutting, preventing displacement and deformation, thereby improving package reliability and electrical performance. Furthermore, the basic etch marks can reduce cutting burrs. The width of a basic etch mark is less than the width of its corresponding primary etch mark, and the width of a basic etch mark is less than or equal to the width of its corresponding secondary etch mark.

[0020] In an optional embodiment, the basic cutting channel is filled with insulating material.

[0021] In one optional embodiment, the first buffer groove is located at the bottom of the base cutting channel, and the depth of the first buffer groove relative to the bottom of the base cutting channel is greater than the depth difference between the corresponding primary cutting channel and the base cutting channel.

[0022] In an optional embodiment, the first buffer groove is located outside the base cutting channel and the depth of the first buffer groove is greater than the depth of the base cutting channel.

[0023] In an optional embodiment, a second buffer slot is also included.

[0024] The second buffer groove is located at the middle position of the bottom of the basic cutting channel;

[0025] The depth of the second buffer groove relative to the bottom of the base cutting channel is greater than the depth difference between the corresponding primary cutting channel and the base cutting channel;

[0026] The second buffer groove is filled with insulating material.

[0027] When a cutting process creates a cutting channel, the depth of the cutting channel is slightly greater than the depth of the base cutting channel, so that the cutting channel covers the base cutting channel. This limits the depth of the first buffer groove and the second buffer groove, ensuring that the first buffer groove and the second buffer groove still exist after the cutting process rather than being cut off by the cutting process.

[0028] In one optional embodiment, the frame connecting bar is a solid bar, including the connecting bar body and the connecting support bar, and the pipe foot is connected to the connecting bar body through the connecting support bar.

[0029] In an optional embodiment, a second buffer groove is further included, which is disposed at the middle position of the connecting rib body;

[0030] The depth of the second buffer groove is greater than the corresponding depth of the first cutting channel;

[0031] The second buffer groove is filled with insulating material.

[0032] In one optional embodiment, the second buffer groove is one of a rectangular buffer groove, an arc-shaped buffer groove, a wedge-shaped buffer groove, or a trapezoidal buffer groove.

[0033] When the frame connecting rib has a basic cutting channel and the second buffer groove is a conical buffer groove or a trapezoidal buffer groove, the larger end of the conical buffer groove or the trapezoidal buffer groove faces the middle of the basic cutting channel.

[0034] In one optional embodiment, the length of the second buffer groove along the length of the frame connecting rib is greater than the width corresponding to the pipe foot.

[0035] In an optional embodiment, the second buffer groove and the first buffer groove have the same depth.

[0036] During the formation of the electroplating layer, the second buffer tank is filled with insulating material, preventing the electroplating layer from forming at the location of the second buffer tank. This creates a second buffer space at the location of the electroplating layer. When the secondary cutting process uses a worn cutting tool, the second buffer space reduces the contact and compression between the tapered, worn cutting edge of the cutting tool and the electroplating layer, further alleviating the problem of electroplating burrs at the pin locations and reducing the amount of electroplating material squeezed. Furthermore, the second buffer space reduces the amount of copper cut when the cutting tool cuts the frame connecting ribs, thereby reducing tool wear and saving costs.

[0037] In one optional embodiment, the first buffer groove is one of a rectangular buffer groove, an arc-shaped buffer groove, a wedge-shaped buffer groove, or a trapezoidal buffer groove.

[0038] When the frame connecting rib has a basic cutting channel and the first buffer groove is a wedge-shaped buffer groove, the larger end of the wedge-shaped buffer groove faces the middle of the basic cutting channel.

[0039] In one optional embodiment, the insulating material is a molding compound.

[0040] In an optional embodiment, the length of the first buffer groove along the length of the frame connecting rib is greater than the width corresponding to the pipe foot.

[0041] In one optional embodiment, the lead frame structure is a lead frame structure corresponding to a wettable side-wing chip package structure.

[0042] The advantages of the technical solution in this application are:

[0043] By forming a first buffer groove, during secondary cutting, the subsequently formed electroplated layer can provide a first buffer space for deformation of the electroplated layer on the surface of the frame connecting rib at the first buffer groove position. This prevents the deformation of the electroplated layer at the frame connecting rib position first contacted by the cutting tool from being transmitted to the electroplated layer at the pipe feet on both sides. At the same time, the adhesion force between the insulating material and the electroplated burr is less than that between the pipe feet and the electroplated burr. The squeezed electroplated layer is washed away by the cutting water in the first buffer space and will not adhere to the insulating material or the pipe feet position, thereby alleviating the problem of electroplated burrs at the pipe feet position during secondary cutting and improving product quality.

[0044] Furthermore, a second buffer groove is formed in the frame connecting rib to reduce the amount of electroplated layer that is squeezed and deformed by the frame connecting rib. This allows the subsequently formed electroplated layer to form a second buffer space at the position of the second buffer groove, further alleviating the problem of electroplating burrs at the pin position and reducing the amount of copper cut when the cutting tool cuts the frame connecting rib, thereby reducing the wear of the cutting tool and saving costs.

[0045] Furthermore, the lead frame structure provided in this application only requires an additional etching process to form the first and second buffer grooves after a single half-etching to form the basic cutting path. This can alleviate the problem of electroplating burrs caused by secondary cutting of Wettable Flank QFN products. The overall lead frame structure is simple, the process is not complicated, and the effect of alleviating the formation of electroplating burrs is significant, making it suitable for widespread use. Attached Figure Description

[0046] Figure 1 This is a top view of the lead frame unit in one embodiment of this application.

[0047] Figure 2 for Figure 1 A partially enlarged structural diagram of part A (without molding compound);

[0048] Figure 3 for Figure 2 Schematic diagram of the cross-sectional structure along the B-B1 axis;

[0049] Figure 4 for Figure 3 A schematic diagram of a structure filled with molding compound;

[0050] Figure 5 This is a schematic diagram of the process and structure of forming a cutting channel and an electroplating layer in a single cutting process according to an embodiment of this application;

[0051] Figure 6 This is a schematic diagram of the secondary cutting process in one embodiment of this application (replacing the narrow cutting tool). Figure 7 for Figure 6 A magnified schematic diagram of the structure of C in the middle;

[0052] Figure 8 for Figure 7 A simulated diagram illustrating the deformation of the electroplated layer during the secondary cutting process;

[0053] Figure 9 This is a partial cross-sectional view of the lead frame structure in another embodiment;

[0054] Figure 10 This is a partial cross-sectional view of the lead frame structure in another embodiment;

[0055] Figure 11 This is a partial cross-sectional view of the lead frame structure in another embodiment;

[0056] Figure 12 This is a partial cross-sectional view of the lead frame structure in another embodiment;

[0057] Figure 13 This is a top view schematic diagram of the lead frame unit in another embodiment;

[0058] Figure 14 for Figure 13 A magnified schematic diagram of part of D (without molding compound).

[0059] The labels for the attached figures are as follows:

[0060] 1. Frame connecting rib; 11. Foundation cutting track; 12. Primary cutting track; 13. Secondary cutting track; 14. Connecting rib body; 15. Connecting support rib; 2. Pipe foot; 3. First buffer groove; 31. First buffer space; 4. Electroplating layer; 5. Insulating material; 6. Cutting tool; 7. Second buffer groove; 71. Second buffer space; 100. Frame unit; 101. Base island. Detailed Implementation

[0061] 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. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0062] It should be understood that terms such as “first” and “second” used herein to describe various elements, components, regions, layers, and / or sections should not be limited by these terms. These terms may be used only to distinguish one element, component, region, layer, or section from another. For example, the use of terms such as “first” and “second” herein does not imply order or sequence unless the context clearly indicates otherwise. For ease of description, spatially relative terms such as “upper” and “lower” may be used herein to describe the relationship of one element or feature to other elements or features as shown in the accompanying drawings. It should be understood that spatially relative terms are intended to include not only the orientations shown in the accompanying drawings but also different orientations of the device in use or operation.

[0063] In this application, unless otherwise expressly specified and limited, the terms "connected" and "connected" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0064] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples. It should be noted that the terms "comprising" and "having," and their variations, used in this application are intended to cover non-exclusive inclusion.

[0065] In actual production and manufacturing processes, for example, Wettable Flank QFN products undergo two cutting processes during packaging. The first cutting process creates a first cutting channel. Simultaneously, to increase the wettability of the exposed pins on the sides of the QFN product by solder, an electroplating layer is formed again at the pins and the corresponding frame ribs within the first cutting channel. The electroplated layer is evenly distributed on the surface of the frame ribs. Because the secondary cutting tool is thinner, it will wear down after prolonged use, causing the cutting part of the secondary cutting tool to have a pointed conical structure. During the secondary cutting process, the electroplated metal (e.g., tin) located at the frame ribs corresponding to the pins within the first cutting channel is easily squeezed towards the pins on both sides, thus forming electroplated burrs (e.g., tin burrs), which can cause short circuits in the product and affect product quality.

[0066] Therefore, this application provides a lead frame structure suitable for secondary cutting, in conjunction with reference to... Figures 1-14 ,in Figure 1 This is a top view schematic diagram of the lead frame structure in one embodiment of this application. Figure 2 for Figure 1 A magnified view of a portion of region A (without molding compound). Figure 3 for Figure 2 Schematic diagram of the cross-sectional structure along line B-B1. Figure 4 for Figure 3 A schematic diagram of a structure filled with molding compound. Figure 5 This is a schematic diagram illustrating the process and structure of forming a cutting path and an electroplating layer in a single cutting process according to an embodiment of this application. Figure 6 This is a schematic diagram of the secondary cutting process in one embodiment of this application (replacing the narrow cutting tool). Figure 7 for Figure 6 A magnified schematic diagram of a portion of C. Figure 8 for Figure 7A simulation diagram illustrating the deformation of the electroplated layer during the secondary cutting process. Figure 9 This is a partial cross-sectional view of the lead frame structure in another embodiment. Figure 10 This is a partial cross-sectional view of the lead frame structure in another embodiment. Figure 11 This is a partial cross-sectional view of the lead frame structure in another embodiment. Figure 12 This is a partial cross-sectional view of the lead frame structure in another embodiment. Figure 13 This is a top view schematic diagram of the lead frame unit in another embodiment. Figure 14 for Figure 13 A partially enlarged structural diagram of D (without molding compound), the lead frame structure suitable for secondary cutting includes:

[0067] Frame unit 100, the frame unit 100 includes pin 2;

[0068] A frame connecting rod 1 is disposed between adjacent frame units 100, and the frame connecting rod 1 is connected to the pin 2 of the frame unit;

[0069] At least one first buffer groove 3 is formed near the pipe foot 2 of the frame connecting rib 1. The depth of the first buffer groove 3 is greater than the depth of the corresponding primary cutting channel 12. The first buffer groove 3 is located inside the corresponding secondary cutting channel 13. The primary cutting channel 12 is a primary cutting groove formed by a primary cutting process. The secondary cutting channel 13 is a secondary cutting channel formed by a secondary cutting process at the bottom of the primary cutting groove. The width of the primary cutting channel 12 is greater than the width of the corresponding secondary cutting channel 13, and the secondary cutting channel 13 is located inside the primary cutting channel 12.

[0070] The first buffer groove 3 is filled with insulating material 5. The adhesion force between the insulating material 5 and the electroplated burrs is less than the adhesion force between the pin 2 and the electroplated burrs.

[0071] In one embodiment, the lead frame includes a plurality of frame units 100, each frame unit 100 including a base island 101 and a plurality of pins 2 respectively disposed around the base island 101, and the base island 101 and pins 2 of adjacent frame units 100 are connected by frame ribs 1 (Dambar).

[0072] In one embodiment, pin 2 may be located on one or more sides of base island 101.

[0073] In other embodiments, the lead frame may also be without the base island 101, and the chip pins may be directly connected via long pins.

[0074] In one embodiment, please refer to Figures 4-7The frame connecting bar 1 includes a bar body 14 and a connecting support bar 15. The tube feet 2 are located on both sides of the bar body 14. The tube feet 2 are connected to the frame connecting bar 1 body through the connecting support bar 15. The first buffer groove 3 is located in the connecting bar body 14 corresponding to the tube feet 2 and is close to the connecting support bar 15.

[0075] In one embodiment, the first buffer groove 3 includes two, and the two first buffer grooves 3 are respectively located inside the frame connecting rib 1 and respectively located on both sides near the tube foot 2.

[0076] A first buffer groove 3 is provided on each side of the frame connecting rib 1 near the tube foot 2. This allows the electroplated layer 4 formed at the frame connecting rib to form two first buffer spaces 31 on the surface of the first buffer groove 3. The two first buffer spaces 31 are located on both sides of the frame connecting rib 1 where the cutting tool 6 first contacts the electroplated layer 4, thus alleviating the problem of electroplating burrs on both sides of the tube foot 2 and further improving product quality.

[0077] The length of the first buffer groove 3 along the length of the frame connecting rib is greater than the width of the corresponding pin 2. The wider first buffer groove 3 isolates the pin from the frame connecting rib, allowing the electroplated layer 4 formed at the frame connecting rib location to create two first buffer spaces 31 on the surface of the first buffer groove 3. This prevents the deformed electroplated layer 4 from contacting the pin 2 and forming electroplating burrs. The first buffer groove 3 can be a discontinuous buffer groove or a continuous buffer groove.

[0078] For actual use, please refer to Figures 4-7A single cutting process forms a cutting channel 12. An electroplated layer 4 is formed at the pin 2 and the frame connecting rib 1 within the cutting channel 12. Because the first buffer groove 3 is filled with a non-conductive insulating material 5, the electroplated layer 4 cannot be formed at the location of the first buffer groove 3. That is, the electroplated layer 4 forms a first buffer space 31 at the location of the first buffer groove 3. The first buffer space 31 is used to provide space for deformation of the electroplated layer 4 when the cutting tool 6 cuts the packaging structure. When a secondary cutting process is performed on the frame connecting rib 1 corresponding to the pin 2 within the primary cutting channel 12 using a cutting tool 6, the cutting part of the secondary cutting tool has a pointed conical structure. When the cutting tool 6 contacts the electroplated layer 4 and generates stress and compression on the electroplated layer 4, the deformation of the electroplated layer 4 is interrupted in the first buffer space 31 because the electroplated layer 4 cannot be formed at the first buffer groove 3. This prevents the deformation of the electroplated layer 4 at the frame connecting rib 1 position first contacted by the cutting tool 6 from being transmitted to the electroplated layer 4 at the pin 2 positions on both sides. At the same time, since the adhesion force between the insulating material 5 and the electroplated burr is less than that between the pin 2 and the electroplated burr, the electroplated layer 4 squeezed in the first buffer space 31 on the surface of the insulating material is washed away by the cutting water and will not adhere to the insulating material 5 or the pin 2 position, thereby alleviating the problem of electroplated burrs on the electroplated layer 4 at the pin 2 position and improving product quality.

[0079] In actual use, the secondary cutting process forms a secondary cutting channel 13. The width of the secondary cutting channel 13 is smaller than the width of the corresponding primary cutting channel 12. The first buffer groove 3 is located inside the connecting rib body 14 corresponding to the pin 2 and inside the corresponding secondary cutting channel 13. The first buffer groove 3 is cut off during the secondary cutting process to ensure the flatness and appearance integrity of the product. Therefore, the lead frame structure of this embodiment does not affect the appearance and function of the final chip package product structure.

[0080] In one embodiment, please refer to Figures 1-4 The frame connecting rib 1 is a semi-etched rib, and the frame connecting rib 1 has a base cutting channel 11 formed after the semi-etching. The depth of the base cutting channel 11 is less than or equal to the depth of the corresponding primary cutting channel 12. The first buffer groove 3 is located at the bottom of the base cutting channel 11, and the depth of the first buffer groove 3 relative to the bottom of the base cutting channel 11 is greater than the depth difference between the corresponding primary cutting channel 12 and the base cutting channel 11. Since the depth of the primary cutting channel 12 formed by the primary cutting is greater than the depth of the base cutting channel 11, the bottom of the primary cutting channel 12 formed after the primary cutting still exposes the first buffer groove 3.

[0081] In practical use, the basic etch path is formed through a semi-etching process. The basic etch path provides a clear path for the cutting tool, reduces cutting resistance and tool wear, and improves cutting efficiency and accuracy. At the same time, the basic etch path can also form a connection between lead frame units, ensuring the stability of the frame structure during cutting, preventing displacement and deformation, thereby improving the reliability and electrical performance of the package. In addition, the basic etch path can also reduce cutting burrs.

[0082] In one embodiment, please refer to Figure 3 The basic cutting channel 11 and the first buffer groove 3 of the lead frame structure are filled with insulating material 5, such as molding compound or other suitable material. The adhesion force between the insulating material 5 and the electroplating burr is less than that between the pin 2 and the electroplating burr. This allows the squeezed electroplating layer 4 to be easily washed away by the cutting water in the first buffer space 31 on the surface of the insulating material, preventing it from adhering to the insulating material 5 or extending beyond the insulating material to the pin 2. This alleviates the problem of electroplating burrs on the pin 2 and improves product quality.

[0083] In other embodiments, insulating material may be filled only in the first buffer groove of the lead frame structure, while the basic cutting path is not filled with insulating material, thereby reducing subsequent cutting resistance and tool wear.

[0084] In one embodiment, please refer to Figures 1-4 The lead frame structure further includes a second buffer groove 7, which is disposed relative to the first buffer groove 3 and located at the middle position of the bottom of the base cutting channel 11; the depth of the second buffer groove 7 relative to the bottom of the base cutting channel 11 is greater than the depth difference between the corresponding primary cutting channel 12 and the base cutting channel 11; the second buffer groove 7 is filled with insulating material, and the insulating material filled in the second buffer groove 7 can be the same as or different from the insulating material filled in the first buffer groove 3.

[0085] During the formation of the electroplated layer, the second buffer tank 7 is filled with insulating material, preventing the electroplated layer from forming at the location of the second buffer tank 7. This results in the electroplated layer 4 forming a second buffer space 71 at the location of the second buffer tank 7. When the secondary cutting process uses a worn cutting tool 6, the second buffer space 71 reduces the contact and compression between the tapered worn cutting part of the cutting tool 6 and the electroplated layer 4, thus reducing the amount of compression and further alleviating the problem of electroplating burrs at the pin locations. Furthermore, the second buffer space 71 also reduces the amount of copper cut when the cutting tool cuts the frame connecting ribs, thereby reducing the wear of the cutting tool and saving costs.

[0086] In one embodiment, the position of the second buffer groove corresponds to the position of the first buffer groove, and its length along the length direction of the frame connecting rib is greater than the width corresponding to the pipe foot. The second buffer groove can be a discontinuous buffer groove or a continuous buffer groove.

[0087] In one embodiment, the first buffer groove 3 is one of a rectangular buffer groove, an arc-shaped buffer groove, a wedge-shaped buffer groove, or a trapezoidal buffer groove. When the first buffer groove is a wedge-shaped buffer groove, the larger end of the wedge-shaped buffer groove faces the middle of the basic cutting channel.

[0088] In one specific embodiment, please refer to Figure 2 and Figure 3 The first buffer groove 3 is a wedge-shaped buffer groove.

[0089] In one embodiment, the second buffer groove 7 is one of a rectangular buffer groove, an arc-shaped buffer groove, a wedge-shaped buffer groove, or a trapezoidal buffer groove.

[0090] In one embodiment, the first buffer groove 3 and the second buffer groove 7 have the same depth and are formed using the same etching process.

[0091] In another embodiment, the first buffer groove 3 and the second buffer groove 7 have different shapes and depths.

[0092] In one embodiment, please refer to Figure 9 The bottom of the basic cutting channel 11 of the lead frame structure has a first buffer groove 3 but no second buffer groove 7. The insulating material filled in the first buffer groove is used to prevent the deformation of the electroplated layer 4 at the position of the frame connecting rib 1 first contacted by the cutting tool 6 from being transmitted to the electroplated layer 4 at the positions of the tube feet 2 on both sides.

[0093] In one embodiment, please refer to Figure 10 The frame connecting rib 1 includes a rib body 14 and a connecting support rib 15. The tube feet 2 are located on both sides of the rib body 14. The tube feet 2 are connected to the frame connecting rib 1 body through the connecting support rib 15. The first buffer groove 3 is located inside the connecting support rib 15.

[0094] In other embodiments, please refer to Figure 13 and Figure 14 The frame connecting rib can also be directly connected to the pipe foot. The two first buffer grooves 3 are located on the frame connecting rib 1 and are respectively close to the pipe foot 2 on both sides.

[0095] In one embodiment, please refer to Figure 11The frame connecting rib 1 is a semi-etched rib. The frame connecting rib 1 has a base cutting channel 11 formed after semi-etching. However, the first buffer groove 3 is located outside the base cutting channel 11, and the depth of the first buffer groove 3 is greater than the depth of the base cutting channel 11. The first buffer groove 3 and the base cutting channel 11 are filled with insulating material (insulating material not shown).

[0096] In one embodiment, please refer to Figure 12 The frame connecting rib 1 is a solid rib, including a connecting rib body 14 and connecting support ribs 15. The pipe foot 2 is connected to the connecting rib body 14 through the connecting support ribs 15. The first buffer groove 3 is located on the connecting rib body 14 and is close to the connecting support ribs 15 on both sides. The second buffer groove 7 is located in the middle of the connecting rib body 14. The depth of the first buffer groove 3 and the second buffer groove 7 is greater than the depth of the corresponding primary cutting channel 12, and the first buffer groove 3 and the second buffer groove 7 are filled with insulating material.

[0097] In another embodiment, the frame connecting rib is a solid rib, and the middle position of the connecting rib body may not have a second buffer groove.

[0098] In one embodiment, the lead frame structure is a lead frame structure corresponding to a wettable side-wing chip package structure. In other embodiments, the lead frame structure can also be applied to lead frame structures corresponding to other secondary-cut chip package structures.

[0099] In one embodiment, pin 2 is a pin array structure corresponding to a DFN package structure, comprising multiple pins spaced apart. In other embodiments, pin 2 is a pin array structure corresponding to a QFN package structure.

[0100] Although this application has been disclosed above with reference to preferred embodiments, it is not intended to limit this application. Any person skilled in the art can make possible changes and modifications to the technical solutions of this application by utilizing the methods and techniques disclosed above without departing from the spirit and scope of this application. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of this application without departing from the content of the technical solutions of this application shall fall within the protection scope of the technical solutions of this application.

Claims

1. A lead frame structure suitable for secondary cutting, characterized in that, include Frame unit, the frame unit including pins; Frame connecting bars are provided between adjacent frame units, and the frame connecting bars are connected to the pins of the frame units; At least one first buffer groove is formed near the pipe foot of the frame connecting rib. The depth of the first buffer groove is greater than the depth of the corresponding primary cutting channel. The first buffer groove is located inside the corresponding secondary cutting channel. The primary cutting channel is the primary cutting groove formed during the primary cutting process. The secondary cutting channel is the secondary cutting channel formed during the secondary cutting process at the bottom of the primary cutting groove. The width of the primary cutting channel is greater than the width of the corresponding secondary cutting channel, and the secondary cutting channel is located inside the primary cutting channel. The first buffer groove is filled with insulating material, and the adhesion between the insulating material and the electroplated burr is less than the adhesion between the pin and the electroplated burr.

2. The lead frame structure suitable for secondary cutting as described in claim 1, characterized in that, The frame connecting bar includes a connecting bar body and a connecting support bar. The tube feet are located on both sides of the connecting bar body, and the tube feet are connected to the connecting bar body through the connecting support bars. The first buffer groove is located inside the connecting support bar.

3. The lead frame structure suitable for secondary cutting as described in claim 1, characterized in that, The frame connecting bar includes a connecting bar body and a connecting support bar. The tube feet are located on both sides of the connecting bar body, and the tube feet are connected to the connecting bar body through the connecting support bars. The first buffer groove is located on the connecting rib body and is close to the connecting support ribs on both sides.

4. The lead frame structure suitable for secondary cutting as described in claim 1, characterized in that, The frame connecting rib is directly connected to the tube foot, and the first buffer groove is located on the frame connecting rib and close to the tube foot on both sides.

5. A lead frame structure suitable for secondary cutting as described in claim 1, characterized in that, The frame connecting ribs are semi-etched ribs, and the frame connecting ribs have basic cutting channels. The depth of the basic cutting channels is less than or equal to the depth of the corresponding primary cutting channel.

6. A lead frame structure suitable for secondary cutting as described in claim 5, characterized in that, The basic cutting channel is filled with insulating material.

7. A lead frame structure suitable for secondary cutting as described in claim 5, characterized in that, The first buffer groove is located at the bottom of the base cutting channel, and the depth of the first buffer groove relative to the bottom of the base cutting channel is greater than the depth difference between the corresponding primary cutting channel and the base cutting channel.

8. A lead frame structure suitable for secondary cutting as described in claim 5, characterized in that, The first buffer groove is located outside the base cutting channel and the depth of the first buffer groove is greater than the depth of the base cutting channel.

9. A lead frame structure suitable for secondary cutting as described in claim 5, characterized in that, It also includes a second buffer slot. The second buffer groove is located at the middle position of the bottom of the basic cutting channel; The depth of the second buffer groove relative to the bottom of the base cutting channel is greater than the depth difference between the corresponding primary cutting channel and the base cutting channel; The second buffer groove is filled with insulating material.

10. A lead frame structure suitable for secondary cutting as described in claim 1, characterized in that, The frame connecting reinforcement is a solid reinforcement body, including the connecting reinforcement body and the connecting support reinforcement. The pipe foot is connected to the connecting reinforcement body through the connecting support reinforcement.

11. A lead frame structure suitable for secondary cutting as described in claim 10, characterized in that, It also includes a second buffer groove, which is located at the middle position of the connecting rib body; The depth of the second buffer groove is greater than the corresponding depth of the first cutting channel; The second buffer groove is filled with insulating material.

12. A lead frame structure suitable for secondary cutting as described in claim 9 or 11, characterized in that, The second buffer groove is one of a rectangular buffer groove, an arc-shaped buffer groove, a wedge-shaped buffer groove, or a trapezoidal buffer groove.

13. A lead frame structure suitable for secondary cutting as described in claim 9 or 11, characterized in that, The length of the second buffer groove along the length of the frame connecting rib is greater than the width corresponding to the pipe foot.

14. A lead frame structure suitable for secondary cutting as described in claim 9 or 11, characterized in that, The second buffer groove has the same depth as the first buffer groove.

15. A lead frame structure suitable for secondary cutting as described in claim 1, characterized in that, The first buffer groove is one of a rectangular buffer groove, an arc-shaped buffer groove, a wedge-shaped buffer groove, or a trapezoidal buffer groove.

16. A lead frame structure suitable for secondary cutting as described in claim 1, 6, 9 or 11, characterized in that, The insulating material is a molding compound.

17. A lead frame structure suitable for secondary cutting as described in claim 1, characterized in that, The length of the first buffer groove along the length of the frame connecting rib is greater than the width corresponding to the pipe foot.

18. A lead frame structure suitable for secondary cutting as described in claim 1, characterized in that, The lead frame structure is the lead frame structure corresponding to the wettable side wing chip packaging structure.

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