Leadframe package structure and packaging method
Patent Information
- Application Number
- CN202611460520.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-09-20
- Publication Date
- 2026-10-27
Smart Images
Figure CN122995686A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of leadframe packaging technology, and in particular to a leadframe packaging structure and packaging method. Background Technology
[0002] With the rapid development of the semiconductor industry, DFN (Dual Flat No-lead) and QFN (Quad Flat No-lead) structures are widely used in the semiconductor industry. Since the base island and lead pads need to be soldered with solder paste during the board soldering process, the flux in the solder paste will vaporize and evaporate during the heating process. The generated gas is difficult to completely expel in the soldering area, which can easily lead to voids in the soldering area, thus affecting the reliability of DFN and QFN packaged devices. Summary of the Invention
[0003] The purpose of this invention is to provide a lead frame packaging structure and packaging method that improves the soldering reliability of DFN and QFN packaged devices and reduces the occurrence of voids in the soldering area.
[0004] In a first aspect, the present invention provides a lead frame packaging structure, comprising: A base island, wherein a chip is mounted on one side of the base island, and the chip is electrically connected to a pin; A molding compound that encapsulates the chip; The base island has a first trench on the side away from the chip; A conductive film is pressed onto the side of the base island where the first trench is located, and maintains the cavity structure of the first trench. A metal layer is disposed on the side of the conductive film away from the base island; The base island and the pin are spaced apart to form a first groove, the conductive film is disconnected at the first groove, and the metal layer is disconnected at the first groove.
[0005] In an optional embodiment, the surface of the molding compound near the base island is flush with the surface of the base island on which the chip is located.
[0006] In an optional embodiment, the sidewall of the first trench is provided with a through hole.
[0007] In an optional implementation, a first stepped groove is formed on the side of the base island away from the chip, and the first stepped groove is connected to the first recess.
[0008] In an optional embodiment, the conductive film has a first cross-section at the break point of the first groove, and the metal layer has a second cross-section at the break point of the first groove, with the first cross-section and the second cross-section being flush; the first cross-section and the second cross-section are respectively flush with the sidewall of the first stepped groove. Alternatively, the first cross-section and the second cross-section may extend beyond the sidewall of the first stepped groove.
[0009] In an optional embodiment, the sidewall of the first stepped groove is provided with a through hole.
[0010] In an optional embodiment, the metal layer has metal pillars on the side facing the base island, and the metal pillars are located in the first step groove.
[0011] In an optional embodiment, the first cross-section is flush with the sidewall of the first stepped groove, and the metal layer is bent at the second cross-section to form a bend, the bend being attached to the first cross-section.
[0012] In an optional implementation, the pin is provided with a second stepped groove.
[0013] Secondly, the present invention provides a packaging method, comprising: A substrate with a molding compound formed on one side is provided; wherein the molding compound encapsulates a chip, and the chip is electrically connected to the substrate; A first groove is formed on the side of the substrate away from the encapsulation body, and the first groove exposes the encapsulation body; the first groove divides the substrate into a base island and a lead. A first trench is formed on the base island; A conductive film and a metal layer are stacked on one side of the first trench; the conductive film covers the opening of the first trench and maintains the cavity structure of the first trench. Cut the metal layer and the conductive film along the first groove; Cut and separate into individual products.
[0014] In an optional embodiment, the step of forming the first trench on the base island further includes: A through hole is formed in the wall of the first trench.
[0015] In an optional embodiment, the step of forming the first groove on the side of the substrate away from the encapsulant further includes: A first stepped groove is formed on the base island; the first stepped groove and the first recess are connected. And / or, a second stepped groove is formed on the pin.
[0016] In an optional embodiment, the step of forming a stacked conductive film and metal layer on one side having the first trench includes: The conductive film is first formed on the substrate by a coating process; The metal layer is then formed on the conductive film.
[0017] In an optional embodiment, after the step of forming a stacked conductive film and metal layer on one side having the first trench, the method further includes: Thin the metal layer.
[0018] In an optional embodiment, the step of forming a stacked conductive film and metal layer on one side having the first trench includes: The conductive film is attached to the metal layer; The metal layer having the conductive film is attached to the substrate.
[0019] In an optional embodiment, after the step of cutting the metal layer and the conductive film along the first groove, the method further includes: The second cross-section of the metal layer is bent to form a bend, and the bend covers the first cross-section of the conductive film.
[0020] The lead frame packaging structure and packaging method provided by this invention have the following advantages: The molding compound is located only on one side of the base island, without covering the sides and back of the base island, resulting in better heat dissipation. A first trench is located on the side of the base island furthest from the chip. A conductive film and metal layer cover the first trench, maintaining its cavity structure, which further enhances heat dissipation. This packaging structure provides better heat dissipation, reduces flux evaporation from the solder paste, and the structure of the first trench facilitates the containment or expulsion of gases, improving gas flow and reducing the occurrence of voids in the soldering area, thus improving soldering reliability. Attached Figure Description
[0021] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0022] Figure 1 This is a schematic diagram of a first structure of the lead frame packaging structure provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the distribution of the first trench in the lead frame packaging structure provided in an embodiment of the present invention; Figure 3This is a schematic diagram of a second structure of the lead frame packaging structure provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of a third type of lead frame packaging structure provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of the fourth structure of the lead frame packaging structure provided in the embodiments of the present invention; Figure 6 for Figure 5 A magnified view of a portion of point A in the middle; Figure 7 This is a schematic diagram of a first structure for connecting the lead frame packaging structure to the substrate according to an embodiment of the present invention. Figure 8 This is a schematic diagram of a second structure for connecting the lead frame packaging structure to the substrate according to an embodiment of the present invention; Figure 9 This is one of the process diagrams of the packaging method provided in the embodiments of the present invention; Figure 10 A second schematic diagram of the manufacturing process of the packaging method provided in an embodiment of the present invention; Figure 11 The third schematic diagram of the packaging method provided in the embodiment of the present invention; Figure 12 This is a schematic diagram of the process of pressing a metal layer with metal pillars in the packaging method provided in the embodiment of the present invention.
[0023] Icons: 110-Base island; 111-First trench; 112-First stepped trench; 113-Through hole; 120-Chip; 130-Pin; 132-Second stepped trench; 141-First recess; 150-Molded body; 160-Conductive film; 161-First cross-section; 170-Metal layer; 171-Second cross-section; 172-Metal pillar; 173-Bend; 174-Gap; 200-Substrate; 210-First pad; 220-Second pad; 230-Solder paste; 101-Substrate material; 103-Connecting rib. Detailed Implementation
[0024] 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.
[0025] 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.
[0026] 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.
[0027] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use. 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. In addition, the terms "first," "second," "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.
[0028] Furthermore, terms such as "horizontal," "vertical," and "sag" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.
[0029] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; 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; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.
[0030] The following detailed description of some embodiments of the present invention is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.
[0031] The lead frame packaging structure proposed in this invention is beneficial for improving heat dissipation performance and increasing soldering reliability.
[0032] Please combine Figure 1 and Figure 2The leadframe package structure includes a base island 110, a molding compound 150, a conductive film 160, and a metal layer 170. A chip 120 is mounted on one side of the base island 110, and the chip 120 is electrically connected to the pins 130. The molding compound 150 covers the chip 120. A first trench 111 is provided on the side of the base island 110 away from the chip 120. The conductive film 160 is pressed onto the side of the base island 110 where the first trench 111 is provided, and maintains the cavity structure of the first trench 111. The metal layer 170 is provided on the side of the conductive film 160 away from the base island 110. The base island 110 and the pins 130 are spaced apart to form a first groove 141. The conductive film 160 is disconnected at the first groove 141, and the metal layer 170 is disconnected at the first groove 141 to avoid short-circuit connection between the base island 110 and the pins 130.
[0033] Optionally, the surface of the molding compound 150 near the base island 110 is flush with the surface of the base island 110 where the chip 120 is located. That is, the molding compound 150 is only disposed on one side of the base island 110 and the pins 130, and the molding compound 150 does not fill the first groove 141, i.e., it does not cover the side or back of the base island 110. This improves heat dissipation performance. The first groove 111 helps to contain or expel flux vapors, improving gas flow and preventing voids in the soldering area.
[0034] Optionally, the sidewall of the first groove 111 is provided with through holes 113. The through holes 113 are designed to improve heat dissipation and facilitate the smooth exhaust of gas, thereby improving gas flow. The number, shape, and distribution of the through holes 113 are not limited and can be flexibly designed, as long as exhaust and heat dissipation are achieved.
[0035] Optionally, a first stepped groove 112 is formed on the side of the base island 110 away from the chip 120, and the first stepped groove 112 is connected to the first groove 141. The first stepped groove 112 is provided to facilitate wettable side wing climbing performance and improve welding reliability. Optionally, the sidewall of the first stepped groove 112 is provided with a through hole 113, so that the first stepped groove 112 and the first groove 111 are connected, which is conducive to improving gas flow, thereby improving heat dissipation, and allowing gas to be discharged from the first groove 111 during welding, reducing the risk of voids in the weld.
[0036] Optionally, the conductive film 160 has a first cross-section 161 at the break point of the first groove 141, and the metal layer 170 has a second cross-section 171 at the break point of the first groove 141. The first cross-section 161 and the second cross-section 171 are flush with each other. The first cross-section 161 and the second cross-section 171 are respectively flush with the sidewalls of the first stepped groove 112. It can be understood that the first stepped groove 112 includes a groove bottom and a sidewall, which are set at an angle. In this embodiment, the groove bottom and the sidewall are approximately 90 degrees. The plane where the groove bottom is located is approximately parallel to the upper surface of the base island 110 (the mounting surface of the chip 120), and the sidewall is set along the thickness direction of the base island 110, and the sidewall is approximately perpendicular to the upper surface of the base island 110. The first cross-section 161 and the second cross-section 171 are respectively flush with the sidewalls of the first stepped groove 112. This arrangement helps to increase the heat dissipation space and improve the heat dissipation performance.
[0037] Alternatively, please combine Figure 3 In some other embodiments, the first section 161 and the second section 171 extend beyond the sidewall of the first stepped groove 112. This arrangement helps to increase the contact area between the solder and the metal layer 170, thereby improving the bonding between the solder and the metal layer 170 and increasing the reliability of the welding.
[0038] Optional, please refer to Figure 4 A metal pillar 172 is provided on the side of the metal layer 170 facing the base island 110, and the metal pillar 172 is located within the first stepped groove 112. The metal pillar 172 can improve the bonding between the solder and the metal layer 170, thereby improving the soldering reliability. Furthermore, the metal pillar 172 can prevent solder from entering the sidewall of the first trench 111, avoiding solder blockage of the through hole 113, thus ensuring smooth venting of the through hole 113 and the first trench 111. It can be understood that the metal pillar 172 can be arrayed along the first stepped groove 112 to prevent solder paste 230 from entering the first trench 111, and also to conduct heat, diverting heat to the first trench 111 and the first stepped groove 112, thus improving heat dissipation performance.
[0039] Optional, please refer to Figure 5 and Figure 6 The first section 161 is flush with the sidewall of the first stepped groove 112. The metal layer 170 is bent at the second section 171 to form a bent portion 173, which is attached to the first section 161. That is, the bent portion 173 wraps around the first section 161 of the conductive film 160. This arrangement helps to improve the wettability and side creep of the solder paste 230 and improve the reliability of soldering.
[0040] Optionally, in some embodiments, there may be a gap 174 between the bent portion 173 and the first section 161. This gap 174 is used to store excess solder paste 230 and prevent the solder paste 230 from entering the first trench 111 or blocking the through hole 113.
[0041] Optionally, pin 130 is provided with a second stepped groove 132. The second stepped groove 132 may be provided only on one side of pin 130, such as designing the second stepped groove 132 on the side of pin 130 away from the first groove 141. Alternatively, the second stepped groove 132 may be an annular groove, designed along the circumference of pin 130. The second stepped groove 132 helps to improve the wettability and side creep of solder paste 230, thereby improving soldering reliability. In addition, the design of the second stepped groove 132 also helps to improve heat dissipation performance.
[0042] It should be noted that the metal layer 170 on the pin 130 can also form a metal pillar 172 to improve the bonding performance of the solder; or, a bend 173 can be formed at the cross-section of the metal layer 170 on the pin 130, and the bend 173 covers the cross-section of the conductive film 160 to improve the wettability and side creep of the solder paste 230.
[0043] Optional, please refer to Figure 7 The system also includes a substrate 200, on which a first pad 210 and a second pad 220 are provided. The base island 110 is soldered to the first pad 210, and the pin 130 is soldered to the second pad 220. When the base island 110 and the pin 130 are soldered to the substrate 200 respectively, the solder can climb along the side of the base island 110 or the pin 130 to improve soldering performance. Features such as the first trench 111 and the through hole 113 are conducive to heat dissipation and venting, improving gas flow and thus reducing the occurrence of voids in the soldering area and improving soldering reliability.
[0044] It is easy to understand that, due to the large welding area of the base island 110, the gas generated by the flux in traditional welding processes is difficult to completely escape. In this embodiment, by setting the first groove 111, during welding, the gas can enter the first groove 111 from the through hole 113, which improves the flowability of the gas above the solder, accelerates the gas escape, and thus reduces the phenomenon of voids in the welding area.
[0045] Please combine Figure 8 It showed Figure 4 The diagram shows the structure connected to the substrate 200. The metal pillar 172 can prevent the solder paste 230 from overflowing to the side wall of the first stepped groove 112, thus preventing the through holes 113 of the first stepped groove 112 and the first trench 111 from being blocked and ensuring smooth venting.
[0046] Please combine Figure 9 The present invention also provides a packaging method, which mainly includes the following steps: Step S1: Provide a substrate 101 with a molding compound 150 formed on one side; wherein the molding compound 150 covers the chip 120 and the chip 120 is electrically connected to the substrate 101.
[0047] Optionally, the substrate 101 is made of copper. A chip 120 is mounted on one side of the substrate 101. The chip 120 is bonded to the substrate 101 by an adhesive film layer and then baked. The chip 120 pads are connected to the pins 130 of the substrate 101 using a wire bonding process. Finally, a molding process is used to form a molding compound 150 to protect the wire bonding structure.
[0048] Step S2: A first groove 141 is formed on the side of the substrate 101 away from the encapsulant 150, and the first groove 141 exposes the encapsulant 150; the first groove 141 divides the substrate 101 into a base island 110 and a lead 130.
[0049] Optionally, the substrate 101 can be divided into sections using cutting processes, such as laser cutting or mechanical cutting, to isolate the base island 110 and the pins 130. Compared to the traditional lead frame structure, the cutting in this embodiment requires separately cutting out the connecting ribs 103. Since the connecting ribs in traditional technologies are prone to breakage and bending, this embodiment uses a process of molding before cutting, which can effectively reduce the design of the connecting ribs 103 and utilize the molding compound 150 to provide support and connection, preventing the connecting ribs 103 from breaking or bending. In this embodiment, the molding compound 150 does not fill the first groove 141, which can improve heat dissipation performance.
[0050] Optionally, when forming the first groove 141, a first stepped groove 112 is formed on the base island 110, and the first stepped groove 112 and the first groove 141 are connected to improve welding reliability and improve the climbing performance of the wettable side wing.
[0051] Please combine Figure 10 Step S3: Form the first trench 111 on the base island 110.
[0052] Optionally, a trench is etched on the back side of the substrate 101 (the side surface away from the molding compound 150) using a chemical etching method. Among them, a first trench 111 is etched on the back side of the base island 110, and the first trench 111 serves to dissipate heat and exhaust air.
[0053] Step S4: A conductive film 160 and a metal layer 170 are formed on one side of the first trench 111; the conductive film 160 covers the opening of the first trench 111 and maintains the cavity structure of the first trench 111.
[0054] A conductive film 160 is attached to the metal layer 170, and the metal layer 170 with the conductive film 160 is mounted to the substrate 101. Optionally, a copper plate is used for the metal layer 170 using a copper cladding process. The conductive film 160 is bonded to the metal layer 170, and then the metal layer 170 with the conductive film 160 is laminated onto the base island 110 and the pin 130. Optionally, the metal layer 170 is thinned using a mechanical polishing process to reduce the proportion of copper layer.
[0055] Please combine Figure 11 Step S5: Cut the metal layer 170 and the conductive film 160 along the first groove 141.
[0056] Optionally, the metal layer 170 and the conductive film 160 can be cut using mechanical cutting or laser cutting. After cutting, the metal layer 170 and the conductive film 160 are separated at the first groove 141, that is, the conductive film 160 on the pin 130 and the conductive film 160 on the base island 110 are isolated from each other, and the metal layer 170 on the pin 130 and the metal layer 170 on the base island 110 are isolated from each other. It is easy to understand that if the conductive film 160 has been cut when it is bonded to the metal layer 170, then only the metal layer 170 needs to be cut in step S5. If the conductive film 160 has not been cut when it is bonded to the metal layer 170, then both the metal layer 170 and the conductive film 160 need to be cut in step S5.
[0057] In some embodiments, the connecting rib 103, the conductive film 160 and the metal layer 170 on the connecting rib 103 may be cut together in step S5. Optionally, a second stepped groove 132 may be cut into the connecting rib 103 and the pin 130 respectively.
[0058] It should be noted that in some embodiments, the first cross-section 161 of the conductive film 160 and the second cross-section 171 of the metal layer 170 are flush with each other and are respectively flush with the sidewall of the first stepped groove 112.
[0059] In some embodiments, the first cross-section 161 of the conductive film 160 and the second cross-section 171 of the metal layer 170 are flush and extend beyond the sidewall of the first stepped groove 112. That is, the width of the metal layer 170 is greater than the width of the base island 110, thereby increasing the welding area of the base island 110 and improving the bonding strength.
[0060] Optionally, step S5 may not involve cutting the plastic sealant 150. This staged cutting helps reduce tensile stress during cutting, improves cutting efficiency, reduces tool wear, and enhances cutting quality.
[0061] Step S6: Cutting and separating into individual products. Using a cutting process, the plastic seal is cut 150mm to separate into individual products, completing the process.
[0062] Optionally, in the step of forming the first groove 111 on the base island 110, through holes 113 are formed in the groove wall of the first groove 111 and in the sidewall of the first stepped groove 112 to enhance gas flow and improve heat dissipation and exhaust.
[0063] Optionally, a second stepped groove 132 can be formed on pin 130, which can be done in step S2 or step S5.
[0064] Optionally, in some embodiments, in step S4, a conductive film 160 can be formed on the substrate 101 by coating, and then a metal layer 170 can be formed on the conductive film 160, such as by electroplating to form the metal layer 170, and then the metal layer 170 can be thinned, which has a similar technical effect.
[0065] Please combine Figure 12 Optionally, in step S4, a copper plate with metal pillars 172 can be used. After the copper plate is pressed onto the substrate 101, a conductive film 160 and a metal layer 170 are formed. The metal pillars 172 are located at the first step groove 112.
[0066] Optionally, in some embodiments, in step S5, after cutting the metal layer 170, the second cross-section 171 of the metal layer 170 is bent to form a bent portion 173, and the bent portion 173 covers the first cross-section 161 of the conductive film 160 to improve the wettability and side creep performance of the weld and improve the weld bonding strength.
[0067] It should be noted that when the lead frame packaging structure is soldered to the substrate 200, the soldering heat rises to the first stepped groove 112, the second stepped groove 132, the through hole 113 and the first trench 111. The first stepped groove 112 and the first trench 111 can enhance gas flow and improve the air flow performance above the soldering area, thereby accelerating exhaust and heat dissipation, avoiding the accumulation of heat in the soldering metal layer 170, which would prevent the gas from being discharged and cause voids. The first trench 111 can also improve the heat dissipation performance at the bottom.
[0068] In summary, the lead frame packaging structure and packaging method provided by the embodiments of the present invention have the following beneficial effects, including: The molding compound 150 is located only on one side of the base island 110, without covering the sides and back of the base island 110, resulting in better heat dissipation. A first trench 111 is provided on the side of the base island 110 away from the chip 120. A conductive film 160 and a metal layer 170 cover the first trench 111, maintaining its cavity structure, which further enhances heat dissipation. Through-holes 113 are provided on the sidewalls of the first trench 111 and the first stepped trench 112, improving heat dissipation and venting, and reducing the probability of solder voids. The inclusion of the first stepped trench 112, the second stepped trench 132, the metal pillars 172, or the bends 173 improves the wettable side-climbing performance of the solder. This packaging structure offers better heat dissipation, reduces flux evaporation in the solder paste 230, and the structures such as the first trench 111 facilitate the containment or venting of gases, thereby reducing voids in the soldering area and improving soldering reliability.
[0069] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; any modifications, equivalent substitutions, improvements, etc., should be included within the protection scope of the present invention.
Claims
1. A lead frame packaging structure, characterized in that, include: A base island, wherein a chip is mounted on one side of the base island, and the chip is electrically connected to a pin; A molding compound that encapsulates the chip; The base island has a first trench on the side away from the chip; A conductive film is pressed onto the side of the base island where the first trench is located, and maintains the cavity structure of the first trench. A metal layer is disposed on the side of the conductive film away from the base island; The base island and the pin are spaced apart to form a first groove, the conductive film is disconnected at the first groove, and the metal layer is disconnected at the first groove.
2. The lead frame packaging structure according to claim 1, characterized in that, The surface of the molding compound near the base island is flush with the surface of the base island on which the chip is located.
3. The lead frame packaging structure according to claim 1, characterized in that, The sidewall of the first trench is provided with a through hole.
4. The lead frame packaging structure according to claim 1, characterized in that, A first stepped groove is formed on the side of the base island away from the chip, and the first stepped groove is connected to the first recess.
5. The lead frame packaging structure according to claim 4, characterized in that, The conductive film has a first cross-section at the break point of the first groove, and the metal layer has a second cross-section at the break point of the first groove. The first cross-section and the second cross-section are flush with each other. The first cross-section and the second cross-section are respectively flush with the sidewall of the first stepped groove. Alternatively, the first cross-section and the second cross-section may extend beyond the sidewall of the first stepped groove.
6. The lead frame packaging structure according to claim 4, characterized in that, The sidewall of the first stepped groove is provided with a through hole.
7. The lead frame packaging structure according to claim 4, characterized in that, The metal layer has a metal pillar on the side facing the base island, and the metal pillar is located in the first step groove.
8. The lead frame packaging structure according to claim 5, characterized in that, The first cross-section is flush with the sidewall of the first stepped groove, and the metal layer is bent at the second cross-section to form a bend, which is attached to the first cross-section.
9. The lead frame packaging structure according to any one of claims 1-8, characterized in that, The pin has a second stepped groove.
10. A packaging method, characterized in that, include: A substrate with a molding compound formed on one side is provided; wherein the molding compound encapsulates a chip, and the chip is electrically connected to the substrate; A first groove is formed on the side of the substrate away from the encapsulation body, and the first groove exposes the encapsulation body; the first groove divides the substrate into a base island and a lead. A first trench is formed on the base island; A conductive film and a metal layer are stacked on one side of the first trench; the conductive film covers the opening of the first trench and maintains the cavity structure of the first trench. Cut the metal layer and the conductive film along the first groove; Cut and separate into individual products.
11. The packaging method according to claim 10, characterized in that, The step of forming the first trench on the base island further includes: A through hole is formed in the wall of the first trench.
12. The packaging method according to claim 10, characterized in that, The step of forming the first groove on the side of the substrate away from the encapsulation body further includes: A first stepped groove is formed on the base island; the first stepped groove and the first recess are connected. And / or, a second stepped groove is formed on the pin.
13. The packaging method according to claim 10, characterized in that, The step of forming a stacked conductive film and metal layer on one side having the first trench includes: The conductive film is first formed on the substrate by a coating process; The metal layer is then formed on the conductive film.
14. The packaging method according to claim 10, characterized in that, After the step of forming a stacked conductive film and metal layer on one side having the first trench, the method further includes: Thin the metal layer.
15. The packaging method according to claim 10, characterized in that, The step of forming a stacked conductive film and metal layer on one side having the first trench includes: The conductive film is attached to the metal layer; The metal layer having the conductive film is attached to the substrate.
16. The packaging method according to claim 10, characterized in that, After the step of cutting the metal layer and the conductive film along the first groove, the method further includes: The second cross-section of the metal layer is bent to form a bend, and the bend covers the first cross-section of the conductive film.