Lead frame, packaging structure and forming method thereof

Abstract

The invention discloses a lead frame, a packaging structure and a forming method of the packaging structure. The plurality of pins are positioned around the base island, gaps are formed between the adjacent pins, each pin comprises an inner pin close to the base island and an outer pin far away from the base island, and the inner pin and the outer pin are connected through a connecting part; the UV adhesive tape covers the back surface and / or the front surface of the connecting part of each pin and fills a gap between the connecting parts of the adjacent pins, and the UV adhesive tape is used for preventing a plastic package layer material from overflowing towards the direction of the outer pins through the gap between the adjacent pins when a plastic package layer wrapping the base island and the inner pins is subsequently formed. And after the plastic package layer is formed, the UV adhesive tape is torn off after being irradiated by UV light. And the UV adhesive tape can prevent the plastic package layer material from overflowing outwards and is easy to remove, so that the production efficiency is improved, and the cost is reduced.

Description

Technical Field

[0001] The present application relates to the field of semiconductor packaging, and in particular to a lead frame, a packaging structure and a method for forming the same. Background Art

[0002] As a part of semiconductor package, the lead frame is used to support the packaged semiconductor chip in the semiconductor package and to connect the packaged semiconductor chip with external devices.

[0003] A lead frame is currently provided, referring to Figure 1 The lead frame includes a base island 100 and a pin area 101 located around the base island 100. The pin area 101 has a plurality of pins 103. Each of the pins 103 includes an inner pin 12 close to the base island 100 and an outer pin 13 away from the base island 100 and connected to the inner pin 12. Adjacent pins 103 are connected by connecting ribs 102.

[0004] When the lead frame is applied to packaging in the form of DIP (Dual In-line Package), QFP (Quad Flat Package), SOP (Small Out-Line Package), etc., the outer pins 13 need to be exposed during the packaging process and cannot be covered by the plastic packaging layer. Specifically, during packaging, a semiconductor chip (not shown in the figure) is first mounted on the front of the base island 100, and then a metal wire (not shown in the figure) is formed to connect the semiconductor chip to the inner pin 12 of the pin 103, and then a plastic packaging layer (not shown in the figure) is formed to cover the base island 100, the semiconductor chip and the inner pin.

[0005] When forming the plastic encapsulation layer, upper and lower molds are required, and the connecting ribs and some pins between the connecting ribs are pressed between the upper and lower molds. The connecting ribs 102 are used to prevent the plastic encapsulation layer material from overflowing to the outer pins 13 during the process of forming the plastic encapsulation layer, thereby affecting the subsequent bending process of the outer pins 13. After forming the plastic encapsulation layer, the connecting ribs 102 need to be cut off to separate adjacent pins 103, and the positions where the connecting ribs 102 are cut off need to be electroplated to prevent pin oxidation, which makes the manufacturing process more complicated and the manufacturing efficiency is low. In addition, the cutting and electroplating of the ribs require additional rib cutting equipment and electroplating equipment, which makes the manufacturing cost higher. Summary of the invention

[0006] The technical problem to be solved by the present application is to provide a lead frame, a packaging structure and a method for forming the same, so as to improve the manufacturing efficiency and save the manufacturing cost.

[0007] To this end, an embodiment of the present application provides a lead frame, including:

[0008] Key Island;

[0009] A plurality of pins are located around the base island, with gaps between adjacent pins, each of the pins includes an inner pin close to the base island and an outer pin far from the base island, and the inner pin and the outer pin are connected by a connecting portion;

[0010] A UV tape covering the back and / or front side of the connecting portion of each pin and filling the gap between the connecting portions of adjacent pins, wherein the UV tape is used to prevent the plastic encapsulation layer material from overflowing toward the outer pins through the gaps between adjacent pins when a plastic encapsulation layer is subsequently formed to cover the base island and the inner pins.

[0011] In an optional embodiment, the UV tape is retained after the plastic sealing layer is formed, or the UV tape is torn off after being irradiated with UV light after the plastic sealing layer is formed; the UV tape includes a base film and an adhesive film located on the surface of the base film, and the viscosity of the adhesive film disappears or decreases under the irradiation of UV light; the adhesive film fills the gap between the connecting parts of adjacent pins.

[0012] In an optional embodiment, the UV tape fills up the gaps between the connecting portions of adjacent pins.

[0013] In an optional embodiment, the lead frame includes a plurality of lead frame units arranged in rows and columns, and each lead frame unit includes a base island and a plurality of discrete pins located around the base island.

[0014] In an optional embodiment, there is a center rib between adjacent lead frame units, one end of the outer lead in each lead frame unit away from the connecting portion is connected to the center rib, and the base island is connected to the center rib via a connecting rib.

[0015] In an optional embodiment, the plurality of discrete pins being located around the base island includes: the plurality of discrete pins being located around the base island, or the plurality of discrete pins being located on both sides of the base island.

[0016] Another embodiment of the present application further provides a packaging structure, including:

[0017] A lead frame, the lead frame comprising a base island and a plurality of pins located around the base island, with gaps between adjacent pins, each of the pins comprising an inner pin close to the base island and an outer pin away from the base island, the inner pin and the outer pin being connected via a connecting portion;

[0018] A semiconductor chip mounted on the front side of the base island, wherein the semiconductor chip is electrically connected to the inner pins through metal wires;

[0019] A plastic encapsulation layer covering the semiconductor chip, the base island and the inner pins, wherein the plastic encapsulation layer exposes the outer pins;

[0020] UV tape covering the back and / or front side of the connection portion of each pin and filling the gap between the connection portions of adjacent pins;

[0021] A plastic encapsulation layer covers the semiconductor chip, the base island and the inner pins, and the plastic encapsulation layer exposes the outer pins and the UV tape.

[0022] In an optional embodiment, some of the pins are located around the base island, or some of the pins are located on both sides of the base island.

[0023] Another embodiment of the present application further provides a method for forming a packaging structure, including:

[0024] A lead frame is provided, wherein the lead frame comprises a base island and a plurality of pins located around the base island, wherein there is a gap between adjacent pins, wherein each pin comprises an inner pin close to the base island and an outer pin far from the base island, wherein the inner pin and the outer pin are connected via a connecting portion;

[0025] forming a UV tape covering the back side and / or the front side of the connection portion of each pin and filling the gap between the connection portions of adjacent pins;

[0026] Mounting a semiconductor chip on the front side of the base island;

[0027] forming a metal wire electrically connecting the semiconductor chip to the inner pin;

[0028] A plastic encapsulation layer is formed to cover the semiconductor chip, the base island and the inner pins, the plastic encapsulation layer exposes the outer pins and the UV tape, and the UV tape is used to prevent the plastic encapsulation layer material from overflowing toward the outer pins through the gaps between adjacent pins when the plastic encapsulation layer is formed to cover the semiconductor chip, the base island and the inner pins.

[0029] In an optional embodiment, after the plastic sealing layer is formed, the UV tape is retained, or after the plastic sealing layer is formed, the UV tape is torn off after being irradiated with UV light.

[0030] In an optional embodiment, the base island and the pins each include a relative front side and back side, the semiconductor chip includes a relative active side and back side, the active side has a plurality of discrete pads, the semiconductor chip is mounted with the back side facing down on the front side of the base island, and the pads on the active side of the semiconductor chip are electrically connected to the corresponding inner pins through the metal wires.

[0031] In an optional embodiment, when forming the plastic encapsulation layer, the front and back surfaces of the connecting portion are pressed between upper and lower molds.

[0032] The advantages of the technical solution of this application are:

[0033] In the aforementioned embodiment of the present application, a lead frame, a packaging structure and a method for forming the same, wherein the lead frame includes a UV tape covering the back and / or front side of the connecting portion of each pin and filling the gap between the connecting portions of adjacent pins, and when the UV tape subsequently forms a plastic sealing layer covering the base island and the inner pins (and the semiconductor chip), the plastic sealing layer material can be prevented from overflowing toward the outer pins through the gaps between adjacent pins, and after the plastic sealing layer is formed, the UV tape is torn off after being irradiated with UV light. Specifically, on the one hand, when the plastic encapsulation layer is formed, since the front and back sides of the connecting parts of the pins are pressed between the upper and lower molds, and since the gaps between the connecting parts of adjacent pins are filled with UV tape, when the plastic encapsulation material is injected into the mold to form a plastic encapsulation layer covering the base island and the inner pins (and the semiconductor chip), the plastic encapsulation material cannot overflow from the gaps between the connecting parts of adjacent pins to the positions of the outer pins, thereby preventing the overflowed plastic encapsulation material from affecting the subsequent bending process of the outer pins; on the other hand, the UV tape can be easily formed by a film laminating process, and after the plastic encapsulation layer is formed, the viscosity of the UV tape will disappear or decrease after being irradiated by UV light. The UV tape is small and can be easily removed by the film tearing process, so that the UV tape will not affect the subsequent bending process of the external pins. Compared with the existing lead frame, the lead frame of the present application does not need to be cut and electroplated, and its process is simple, the production efficiency is improved, and the cost is low. In addition, since there is no need for additional investment in related cutting and electroplating equipment, the space of the packaging production line is saved, the investment production line cost is further reduced, and there is no pollution of the electroplating liquid in the packaging process. On the other hand, the UV tape can also fix the external pins during the wiring process and the process of cutting the middle ribs of the lead frame, and can prevent the external pins from moving. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic diagram of the top view structure of the existing lead frame;

[0035] Figure 2-Figure 9 This is a structural schematic diagram of the process of forming a packaging structure in some embodiments of the present application. DETAILED DESCRIPTION

[0036] The specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. When describing the embodiments of the present application in detail, for the sake of convenience, the schematic diagrams will not be partially enlarged according to the general proportion, and the schematic diagrams are only examples, which should not limit the scope of protection of the present application. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0037] An embodiment of the present application first provides a lead frame, combined with reference Figure 2-Figure 5 , Figure 2 This is a schematic diagram of the structure of the back side of the lead frame when there is no UV tape. Figure 3 This is a schematic diagram of the structure of the back side of the lead frame when UV tape is applied. Figure 4 for Figure 3 Schematic diagram of the cross-sectional structure along the cutting line AB. Figure 5 for Figure 3 The schematic diagram of the cross-sectional structure along the cutting line CD direction includes:

[0038] Key Island 200;

[0039] There are a plurality of pins 203 located around the base island 200, with a gap 206 between adjacent pins 203, each of the pins 203 includes an inner pin 33 close to the base island 200 and an outer pin 34 away from the base island 200, and the inner pin 33 and the outer pin 34 are connected by a connecting portion 35 (refer to Figure 2 );

[0040] A UV tape 202 covers the back and / or front side of the connection portion 35 of each pin 203 and fills the gap 206 between the connection portions 35 of adjacent pins. The UV tape 202 is used to prevent the plastic layer material from overflowing toward the outer pin 34 when a plastic layer covering the base island 200 and the inner pin 33 is subsequently formed. After the plastic layer is formed, the UV tape 202 is torn off after being irradiated with UV light.

[0041] The lead frame is used to support the packaged semiconductor chip during the packaging process and is used to connect the packaged semiconductor chip with external devices.

[0042] In one embodiment, the lead frame includes a plurality of lead frame units arranged in rows and columns, each of the lead frame units includes a base island 200 and a pin area 201 located around the base island 200 , and the pin area 201 has a plurality of discrete pins 203 . Figure 2 and Figure 3 Only the structure of one lead frame unit of the lead frame is shown.

[0043] The adjacent inner pins 33, the adjacent connecting parts 35 and some outer pins 34 of the plurality of pins 203 are separated, and there is a gap 206 between adjacent pins 203. In one embodiment, there is a middle rib 204 between adjacent lead frame units, and one end of the outer pin 34 in each lead frame unit away from the connecting part 35 is connected to the middle rib 204, and the base island 200 is connected to the middle rib 204 through a connecting rib 205. After the packaging is completed, the middle rib in the lead frame is subsequently removed by cutting, so that the base island 200 and the pins 203 in each lead frame unit are separated from the middle rib, forming a plurality of discrete packaging structures (one lead frame unit corresponds to one packaging structure).

[0044] The base island 200 is separated from the pin 203, and there is a gap between the base island 200 and the pin 203. The base island 200 and the pin 203 are made of the same material, which is metal or alloy, specifically copper or copper alloy. In order to reduce the stress and weight of the lead frame, in one embodiment, other areas of the lead frame outside the pin area 201 also have a second gap 207.

[0045] There are two situations in which a plurality of discrete pins are located around the base island. In one embodiment, a plurality of discrete pins 203 are located around the base island 200 (eg Figure 2 or Figure 3 In another embodiment, a plurality of discrete pins 203 are located on both sides of the base island 200, such as two opposite sides of the base island 200, and the lead frame can be used for packaging in the form of DIP (Dual In-line Package) or SOP (Small Out-Line Package).

[0046] The base island 200 and the pins 203 each include a front side 23 and a back side 22 opposite to each other. The front side 23 of the base island 200 is used for mounting a semiconductor chip, and the semiconductor chip is electrically connected to the front side of the inner pins 33 of the pins 203 through metal wires.

[0047] The lead frame further includes a UV (Ultraviolet) tape 202, which covers the back side 22 and / or the front side 23 of the connection portion 35 of each lead 203 and fills the gap 206 between the connection portions 35 of adjacent leads. Figure 3-Figure 5, the UV tape 202 covers the back side 22 of the connection portion 35 of each pin 203 and fills the gap 206 between the connection portions 35 of adjacent pins. In another embodiment, the UV tape 202 covers the front side 23 of the connection portion 35 of each pin 203 and fills the gap 206 between the connection portions 35 of adjacent pins. In another embodiment, the UV tape 202 covers the front side 23, the back side 22 of the connection portion 35 of each pin 203 and fills the gap 206 between the connection portions 35 of adjacent pins. In the present application, the lead frame includes the UV tape 202 covering the back side and / or the front side of the connection portion 35 of each pin 203 and filling the gap 206 between the connection portions 35 of adjacent pins, and the UV tape 202 subsequently forms a plastic encapsulation layer 304 (reference) covering the base island 200 and the inner pins 33 (and the semiconductor chip 301). Figure 6-Figure 7 ), it can prevent the plastic layer 304 material from overflowing toward the outer pin 34 through the gap 206 between adjacent pins 203. Specifically, on the one hand, when the plastic layer 304 is formed, the front side 23 and the back side 22 of the connecting portion 35 of the pin 203 are pressed between the upper and lower molds, and the gap 206 between the connecting portions 35 of adjacent pins 203 is filled with the UV tape 202. Therefore, when the plastic material is injected into the upper and lower molds to form the plastic layer 304 covering the base island 200 and the inner pin 33 (and the semiconductor chip 301), the The plastic encapsulation material cannot overflow from the gap 206 between the connecting parts 35 of adjacent pins 203 to the position of the outer pin 34, thereby preventing the overflowed plastic encapsulation material from affecting the subsequent bending process of the outer pin 34; on the other hand, the UV tape 202 can be easily formed by a film laminating process, and after the plastic encapsulation layer 304 is formed, the viscosity of the UV tape 202 will disappear or decrease after being irradiated by UV light, and the UV tape 202 can be easily removed by a film tearing process, so that the UV tape 202 will not affect the subsequent bending process of the outer pin 34. Moreover, the lead frame of the present application does not require rib cutting and electroplating during production, unlike the existing lead frame. The process is simple, production efficiency is improved, and the cost is low. In addition, since there is no need for additional investment in related rib cutting and electroplating equipment, the space of the packaging production line is saved, the investment production line cost is further reduced, and there is no pollution of the electroplating liquid during the packaging process. On the other hand, the UV tape 202 can also fix the pin 203 during the wire bonding process and the process of cutting the middle rib of the lead frame, thereby preventing the pin 203 from moving.

[0048] In one embodiment, after the plastic encapsulation layer 304 is formed, the UV tape 202 can be removed after being irradiated by UV light. In another embodiment, after the plastic encapsulation layer 304 is formed, the UV tape 202 can be retained.

[0049] The UV tape 202 has adhesiveness and ductility, and when irradiated with UV light, the adhesiveness of the UV tape 202 disappears or decreases, and the UV tape 202 can be torn off by a film-tearing process. The UV tape 202 can be formed by a film-sticking process.

[0050] In one embodiment, the UV tape 202 includes a base film and an adhesive film located on the surface of the base film, wherein the adhesiveness of the adhesive film disappears or decreases under the irradiation of UV light; the adhesive film fills the gaps 206 between the connecting portions 34 of adjacent pins 203 .

[0051] In one embodiment, the UV tape 202 fills the gap 206 between the connecting portions 35 of the adjacent pins 203 (see Figure 3 ).

[0052] An embodiment of the present application also provides a packaging structure, referring to Figure 6 and Figure 7 (Combined with reference Figure 2-Figure 5 ), Figure 6 This is a schematic diagram of the bottom view of the packaging structure. Figure 7 for Figure 6 The schematic diagram of the cross-sectional structure along the cutting line CD direction includes:

[0053] A lead frame, the lead frame comprising a base island 200 and a plurality of pins 203 located around the base island 200, with a gap 206 between adjacent pins 203, each of the pins 203 comprising an inner pin 33 close to the base island 200 and an outer pin 34 away from the base island 200, the inner pin 33 and the outer pin 34 being connected via a connecting portion 35;

[0054] A semiconductor chip 301 mounted on the front side 23 of the base island 200, wherein the semiconductor chip 301 is electrically connected to the inner pin 33 via a metal wire 302;

[0055] The UV tape 202 covers the back and / or front of the connection portion 35 of each pin 203 and fills the gap 206 between the connection portions 35 of adjacent pins 203. The UV tape 202 is used to prevent the plastic sealing layer 304 (reference Figure 6 and Figure 7 ) the material overflows toward the outer pin 34 through the gap 206 between the adjacent pins 203;

[0056] A plastic encapsulation layer 304 encapsulates the semiconductor chip 301 , the base island 200 and the inner pins 33 , and the plastic encapsulation layer 304 exposes the outer pins 203 and the UV tape 202 .

[0057] In one embodiment, the lead frame includes a plurality of lead frame units arranged in rows and columns, each lead frame unit includes a base island 200 and a plurality of discrete pins 203 located around the base island 200, and each lead frame unit has the semiconductor chip 301, a plastic encapsulation layer 304 and a UV tape 202.

[0058] In one embodiment, the base island 200 and the pins 203 each include a relative front side and a relative back side, the semiconductor chip 301 includes a relative active side and a relative back side, the active side has a plurality of discrete pads, the back side of the semiconductor chip 301 is mounted on the front side of the base island 200 with the back side facing downward, and the pads on the active side are electrically connected to the corresponding inner pins 33 through metal wires 302. In one embodiment, the back side of the semiconductor chip 301 is mounted on the front side of the base island 200 through an adhesive layer. In one embodiment, the material of the pad is one or more of aluminum, copper, titanium, nickel, tin, tungsten, platinum, chromium, tantalum, gold, and silver, the material of the metal wire 302 is one or more of gold, aluminum, copper, silver, nickel, and palladium, and the formation process of the metal wire 302 includes a wire bonding process or a wire bonding process (Wire Bonding, WB).

[0059] In one embodiment, the semiconductor chip 301 includes but is not limited to a signal processing semiconductor chip, a logic control semiconductor chip, a storage semiconductor chip, a sensor semiconductor chip, a power semiconductor chip or a radio frequency semiconductor chip according to different functions.

[0060] In one embodiment, after the plastic encapsulation layer 304 is formed, the UV tape 202 can be torn off after being irradiated by UV light. In another embodiment, after the plastic encapsulation layer 304 is formed, the UV tape 202 can be retained.

[0061] In one embodiment, the UV tape 202 includes a base film and an adhesive film located on the surface of the base film, wherein the adhesiveness of the adhesive film disappears or decreases under the irradiation of UV light; the adhesive film fills the gaps 206 between the connecting portions 34 of adjacent pins 203 .

[0062] In one embodiment, the front and back surfaces of the connecting portion 35 are used to be pressed between upper and lower molds when forming the plastic encapsulation layer 304 .

[0063] In one embodiment, reference Figure 8After forming the plastic encapsulation layer 304, the middle ribs in the lead frame are cut and removed to form a plurality of discrete packaging structures, and then the UV tape 202 in each packaging structure is irradiated with UV light, and the UV tape 202 is torn off. After the UV tape 202 is torn off, the outer pins 34 in the pins 203 are bent.

[0064] In one embodiment, reference Fig. 9 After forming the plastic encapsulation layer 304 , the middle ribs in the lead frame are cut and removed to form a number of discrete packaging structures, and the UV tape 202 is retained; the outer pins 34 in the pins 203 are bent.

[0065] An embodiment of the present application further provides a method for forming a packaging structure, which is described in detail below with reference to the accompanying drawings.

[0066] refer to Figure 2 , providing a lead frame, the lead frame includes a base island 200 and a plurality of pins 203 located around the base island 200, with gaps 206 between adjacent pins 203, each of the pins 203 includes an inner pin 33 close to the base island 200 and an outer pin 34 away from the base island 200, and the inner pin 33 and the outer pin 34 are connected by a connecting portion 35.

[0067] In one embodiment, the lead frame includes a plurality of lead frame units arranged in rows and columns, each of the lead frame units includes a base island 200 and a pin area 201 located around the base island 200 , and the pin area 201 has a plurality of discrete pins 203 . Figure 2 and Figure 3 Only the structure of one lead frame unit of the lead frame is shown.

[0068] The adjacent inner pins 33, the adjacent connecting parts 35 and some outer pins 34 of the plurality of pins 203 are separated, and there is a gap 206 between adjacent pins 203. In one embodiment, there is a middle rib 204 between adjacent lead frame units, and one end of the outer pin 34 in each lead frame unit away from the connecting part 35 is connected to the middle rib 204, and the base island 200 is connected to the middle rib 204 through a connecting rib 205. After the packaging is completed, the middle rib in the lead frame is subsequently removed by cutting, so that the base island 200 and the pins 203 in each lead frame unit are separated from the middle rib, forming a plurality of discrete packaging structures (one lead frame unit corresponds to one packaging structure).

[0069] The base island 200 and the pins 203 are separated, and there is a gap between the base island 200 and the pins 203 .

[0070] In one embodiment, the lead frame is formed by performing processes such as stamping, etching, and heat treatment on a coiled material.

[0071] In one embodiment, the step further includes performing electroplating to form a protective metal layer on the surface of the pin 203 .

[0072] refer to Figure 3-Figure 5 , Figure 4 for Figure 3 Schematic diagram of the cross-sectional structure along the cutting line AB. Figure 5 for Figure 3 The schematic cross-sectional structure diagram along the cutting line CD direction shows a UV tape 202 that covers the back and / or front of the connecting portion 35 of each pin 203 and fills the gaps between the connecting portions 35 of adjacent pins 203 .

[0073] The UV tape 202 is used to form a plastic layer 304 (see FIG. 1 ) covering the semiconductor chip 301, the base island 200 and the inner pins 33. Figure 6 and Figure 7 ), the material of the plastic encapsulation layer 304 is prevented from overflowing toward the outer pin 34 through the gap 206 between the adjacent pins 203 .

[0074] In one embodiment, after the plastic sealing layer 304 is formed, the UV tape is retained, or after the plastic sealing layer 304 is formed, the UV tape 202 is torn off after being irradiated with UV light.

[0075] In one embodiment, after the plastic encapsulation layer 304 is formed, the UV tape 202 can be removed after being irradiated by UV light. In another embodiment, after the plastic encapsulation layer 304 is formed, the UV tape 202 can be retained.

[0076] The UV tape 202 has adhesiveness and ductility, and when irradiated with UV light, the adhesiveness of the UV tape 202 disappears or decreases, and the UV tape 202 can be torn off by a film-tearing process. The UV tape 202 can be formed by a film-sticking process.

[0077] In one embodiment, the UV tape 202 includes a base film and an adhesive film located on the surface of the base film, wherein the adhesiveness of the adhesive film disappears or decreases under the irradiation of UV light; the adhesive film fills the gaps 206 between the connecting portions 34 of adjacent pins 203 .

[0078] refer to Figure 6 and Figure 7, a semiconductor chip 203 is mounted on the front side of the base island 200; a metal wire 302 is formed to electrically connect the semiconductor chip 203 to the inner pin 33; a plastic layer 304 is formed to cover the semiconductor chip 301, the base island 200 and the inner pin 33, the plastic layer 304 exposes the outer pin 34 and the UV tape 202, and the UV tape 202 is used to prevent the plastic layer 304 material from overflowing toward the outer pin 34 through the gap 203 between adjacent pins 203 when forming the plastic layer 304 covering the semiconductor chip 301, the base island 200 and the inner pin 33.

[0079] In one embodiment, the base island 200 and the pins 203 each include a relative front side and a relative back side, the semiconductor chip 301 includes a relative active side and a relative back side, the active side has a plurality of discrete pads, the back side of the semiconductor chip 301 is mounted on the front side of the base island 200 with the back side facing downward, and the pads on the active side are electrically connected to the corresponding inner pins 33 through metal wires 302. In one embodiment, the back side of the semiconductor chip 301 is mounted on the front side of the base island 200 through an adhesive layer. In one embodiment, the material of the pad is one or more of aluminum, copper, titanium, nickel, tin, tungsten, platinum, chromium, tantalum, gold, and silver, the material of the metal wire 302 is one or more of gold, aluminum, copper, silver, nickel, and palladium, and the formation process of the metal wire 302 includes a wire bonding process or a wire bonding process (Wire Bonding, WB).

[0080] The plastic encapsulation layer 304 is formed by an injection molding process. During the injection molding process, the front and back surfaces of the connecting portion 35 of the pin 203 are pressed between the upper and lower molds, the base island 200, the semiconductor chip 301 and the metal wire 301 are located inside the upper and lower molds, and the external pins 34 are located outside the upper and lower molds. Plastic encapsulation material is injected into the upper and lower molds to form a plastic encapsulation layer 304 covering the semiconductor chip 301, the base island 200 and the inner pins 33, and the plastic encapsulation layer 304 exposes the external pins 34 and the UV tape 202.

[0081] In one embodiment, reference Figure 7 and Figure 8 After the plastic sealing layer 304 is formed, the UV tape 202 is irradiated with UV light and then the UV tape is torn off; the outer pin 34 of the pin 203 is bent.

[0082] In another embodiment, after the plastic sealing layer 304 is formed, the UV tape 202 is retained; the outer pin 34 of the pin 203 is bent, and the UV tape 202 can fix the outer pin 34 during the bending process of the outer pin 34 of the pin 203 to ensure the accuracy of the position of the bent outer pin 34.

[0083] Although the present application has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present application. Any technical personnel in this field can use the methods and technical contents disclosed above to make possible changes and modifications to the technical solution of the present application without departing from the spirit and scope of the present application. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present application without departing from the content of the technical solution of the present application are within the protection scope of the technical solution of the present application.

Claims

1. A lead frame, characterized in that: include: Key Island; A plurality of pins are located around the base island, with gaps between adjacent pins, each of the pins includes an inner pin close to the base island and an outer pin far from the base island, and the inner pin and the outer pin are connected by a connecting portion; A UV tape covering the back and / or front side of the connecting portion of each pin and filling the gap between the connecting portions of adjacent pins, wherein the UV tape is used to prevent the plastic encapsulation layer material from overflowing toward the outer pins through the gaps between adjacent pins when a plastic encapsulation layer is subsequently formed to cover the base island and the inner pins.

2. The lead frame according to claim 1, wherein: The UV tape is retained after the plastic sealing layer is formed, or the UV tape is torn off after being irradiated with UV light after the plastic sealing layer is formed; the UV tape includes a base film and an adhesive film located on the surface of the base film, and the viscosity of the adhesive film disappears or decreases under the irradiation of UV light; the adhesive film fills the gap between the connecting parts of adjacent pins.

3. The lead frame according to claim 1 or 2, characterized in that: The UV tape fills up the gaps between the connecting parts of adjacent pins.

4. The lead frame according to claim 1, wherein: The lead frame includes a plurality of lead frame units arranged in rows and columns, and each lead frame unit includes a base island and a plurality of discrete pins located around the base island.

5. The lead frame according to claim 4, wherein: There is a middle rib between adjacent lead frame units, one end of the outer lead in each lead frame unit away from the connecting portion is connected to the middle rib, and the base island is connected to the middle rib through a connecting rib.

6. The lead frame according to claim 4, wherein: The plurality of discrete pins are located around the base island, including: the plurality of discrete pins are located around the base island, or the plurality of discrete pins are located on both sides of the base island.

7. A packaging structure, characterized in that: include: A lead frame, the lead frame comprising a base island and a plurality of pins located around the base island, with gaps between adjacent pins, each of the pins comprising an inner pin close to the base island and an outer pin away from the base island, the inner pin and the outer pin being connected via a connecting portion; A semiconductor chip mounted on the front side of the base island, wherein the semiconductor chip is electrically connected to the inner pins through metal wires; A plastic encapsulation layer covering the semiconductor chip, the base island and the inner pins, wherein the plastic encapsulation layer exposes the outer pins; UV tape covering the back and / or front side of the connection portion of each pin and filling the gap between the connection portions of adjacent pins; A plastic encapsulation layer covers the semiconductor chip, the base island and the inner pins, and the plastic encapsulation layer exposes the outer pins and the UV tape.

8. The packaging structure according to claim 7, characterized in that: Some of the pins are located around the base island, or some of the pins are located on both sides of the base island.

9. A method for forming a packaging structure, characterized in that: include: A lead frame is provided, the lead frame comprising a base island and a plurality of pins located around the base island, with gaps between adjacent pins, each of the pins comprising an inner pin close to the base island and an outer pin away from the base island and connected to the inner pin, the inner pin and the outer pin being connected via a connecting portion; forming a UV tape covering the back side and / or the front side of the connection portion of each pin and filling the gap between the connection portions of adjacent pins; Mounting a semiconductor chip on the front side of the base island; forming a metal wire electrically connecting the semiconductor chip to the inner pin; A plastic encapsulation layer is formed to cover the semiconductor chip, the base island and the inner pins, the plastic encapsulation layer exposes the outer pins and the UV tape, and the UV tape is used to prevent the plastic encapsulation layer material from overflowing toward the outer pins through the gaps between adjacent pins when the plastic encapsulation layer is formed to cover the semiconductor chip, the base island and the inner pins.

10. The method for forming a package structure according to claim 9, wherein: After the plastic sealing layer is formed, the UV tape is retained, or after the plastic sealing layer is formed, the UV tape is torn off after being irradiated with UV light.

11. The method for forming a package structure according to claim 9, wherein: The base island and the pins each include a relative front side and a relative back side, the semiconductor chip includes a relative active side and a relative back side, the active side has a plurality of discrete pads, the semiconductor chip is mounted with the back side facing downward on the front side of the base island, and the pads on the active side of the semiconductor chip are electrically connected to the corresponding inner pins through the metal wires.

12. The method for forming a package structure according to claim 11, wherein: When forming the plastic sealing layer, the front and back surfaces of the connecting portion are pressed between the upper and lower molds.

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