A LQFP lead frame structure

Abstract

The invention relates to an LQFP lead frame structure, comprising a lead frame and a lead row, wherein the lead row is arranged around the lead frame, a base island is arranged at the center of the lead frame, and the base island is connected to the side of the lead frame by an inclined connector, so that the base island is sunken in the lead frame; the connectors are distributed around the side of the base island, and adjacent connectors are distributed at equal intervals, at least three glue locking holes are arranged on the connectors, and adjacent glue locking holes are connected by drainage grooves, an IC chip is placed on the front side of the base island, and the back side of the base island is a heat dissipation surface, and a circle of overflow grooves is arranged on the surface of the heat dissipation surface; the invention has the beneficial effects of: by setting the glue locking holes, the glue locking force between the encapsulated plastic body and the lead frame can be better, and the reliability between the plastic body and the lead frame is greatly improved; and the overflow groove is arranged at the same time, so that the plastic can be prevented from flowing onto the heat dissipation surface during the process of encapsulating the plastic body.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductors, and in particular relates to an LQFP lead frame structure. Background Art

[0002] With the development of microelectronics technology, semiconductor integrated circuits have been widely used in many important fields such as communications, transportation, energy, military, and national defense. The lead frame used in integrated circuit plastic packaging is a major structural material for integrated circuit packaging. It mainly plays the role of carrying IC chips in the circuit, connecting the chip with the external circuit board electrical signal, and has a mechanical role in installation and fixation. However, at present, some lead frames have a sunken base island, one side of the base island is used to install the IC chip, and the other side is used for heat dissipation. The base island and the lead pins are generally sealed together with a plastic body. During the sealing process, the plastic body often covers the heat dissipation surface of the base island as a whole, which will affect the heat dissipation of the IC chip. Therefore, in order to solve this problem, during the manufacturing process, an injection mold is used to fit the heat dissipation surface of the base island to minimize the flow of plastic onto the heat dissipation surface. However, in the actual manufacturing process, as the number of injection molding times of the injection mold increases, more or less residues will still remain on the heat dissipation surface, which will lead to the subsequent removal of the residues on the heat dissipation surface, which will cause certain damage to the surface of the base island and greatly increase the manufacturing cost. At the same time, since one side of the base island is used as the heat dissipation surface, there cannot be colloid, so the locking force between the plastic body and the base island is not very good and the reliability is poor. Summary of the invention

[0003] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a LQFP lead frame structure with good glue locking force, reliable performance and greatly improved manufacturing process.

[0004] The objective of the present invention is achieved through the following technical scheme. An LQFP lead frame structure comprises a lead frame and a lead row, wherein the lead row is located around the lead frame, a base island is provided at the center of the lead frame, and the base island is connected to the side of the lead frame by an inclined connector, so that the base island is sunk into the lead frame; the connectors are distributed around the side of the base island, and adjacent connectors are distributed at equal intervals, at least three glue locking holes are provided on the connector, and adjacent glue locking holes are connected by drainage grooves, an IC chip is placed on the front of the base island, and the back of the base island is a heat dissipation surface, and a circle of overflow grooves is provided on the surface of the heat dissipation surface.

[0005] The beneficial effects of the present invention are as follows: compared with the prior art, the base island and the lead frame are connected by an inclined connector, so that the installation position of the IC chip on the base island is not higher than the height of the lead frame, the IC chip is better protected during the packaging process, and the structure of the plastic body is also more compact; by setting the locking hole, the locking force between the encapsulated plastic body and the lead frame can be better, which greatly improves the reliability between the plastic body and the lead frame; at the same time, an overflow groove is set, which can prevent the plastic from flowing onto the heat dissipation surface during the packaging process of the plastic body, and also plays a role in positioning the lead frame during the packaging process, which greatly improves the manufacturing efficiency.

[0006] Preferably, the lead frame and the lead row are integrally covered by a plastic body, the front side of the plastic body covers the IC chip on the base island, and the back side of the plastic body covers the connector and the lead row; the heat dissipation surface located on the base island is exposed outside the plastic body, and the plane where the back side of the plastic body is located is flush with the heat dissipation surface; such a structural arrangement allows the plastic body to be completely integrated with the lead frame and the lead row, so that the heat from the IC chip can be dissipated in time through the heat dissipation surface.

[0007] Preferably, the connector includes a connecting pin and a bent transition connecting block, the transition connecting block is integrally formed on the side of the base island, one end of the connecting pin is integrally formed on the transition connecting block, and the other end of the connecting pin is integrally formed on the inner side of the lead frame, and the connecting pin is flush with the lead frame, and the transition connecting block and the lead frame are distributed in an inclined state so that the base island is located below the inner side of the lead frame; through the arrangement of the above structure, the connection between the base island and the lead frame is more stable, and at the same time, the base island can be sunk into the lead frame through the connector, and the reliability is better.

[0008] Preferably, the glue locking holes are distributed at equal intervals and are arranged in sequence along the length direction of the transition connection block, and each of the glue locking holes is located at the bending corner of the transition connection block; the glue locking holes are distributed at equal intervals, so that during the process of encapsulating the plastic body, the fluidity of the glue flowing from one side of the lead frame to the other side can be more uniform, and the glue locking holes are located at the bending corners of the transition connection block, so that the glue locking ability between the plastic body and the heat dissipation surface of the base island is better.

[0009] Preferably, the drainage groove is arranged on the back side of the transition connection block, and the drainage groove is arranged along the length direction of the transition connection block and is in a penetrating shape; the drainage groove makes it possible for the colloid to have better fluidity between the various locking holes during the process of encapsulating the plastic body, and can further improve the packaging process between the plastic body and the heat dissipation surface of the base island, greatly reducing obstacles in the packaging process.

[0010] Preferably, the overflow groove is embedded in the base island, the opening of the overflow groove faces the surface of the heat dissipation surface, and the overflow groove is close to the side of the base island, and the overflow groove is connected from end to end; through the overflow groove arranged as above, during the process of packaging the plastic body, part of the colloid can be drained into the overflow groove, which can prevent it from flowing onto the heat dissipation surface. At the same time, the overflow groove is close to the side of the base island, which maximizes the area of ​​the heat dissipation surface and further improves the heat dissipation of the IC chip.

[0011] Preferably, the overflow trough includes four straight trough bodies and four oblique corner trough bodies, the four straight trough bodies and the four oblique corner trough bodies are connected end to end, and the oblique corner trough bodies are located at the corners of the heat dissipation surface; the trough bodies are connected end to end, so that part of the colloid can be drained into the overflow trough for uniform distribution, and at the same time, the oblique corner trough body is located at the corner of the heat dissipation surface, so that part of the colloid at the corner of the heat dissipation surface can flow smoothly into the overflow trough without diffusion.

[0012] Preferably, the four corners of the lead frame are provided with limiting convex strips, and the limiting convex strips are extended outwardly along the lead frame; by providing the limiting convex strips, the combination between the lead frame and the plastic body is better. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 The present invention is a front structural schematic diagram between a lead frame and a lead row.

[0014] Figure 2 The present invention is a schematic diagram of the reverse structure between the lead frame and the lead row.

[0015] Figure 3 The present invention is a schematic diagram of a lead frame structure coated with a plastic body.

[0016] Figure 4 The present invention is a schematic diagram of the entire board structure of an LQFP lead frame structure coated with a plastic body.

[0017] The numbers in the accompanying drawings are: 1, lead frame; 2, lead row; 3, base island; 4, connector; 5, IC chip; 6, overflow groove; 7, plastic body; 8, limiting convex strip; 31, heat dissipation surface; 41, glue locking hole; 42, drainage groove; 43, connecting foot; 44, transition connecting block; 61, straight groove body; 62, oblique corner groove body. DETAILED DESCRIPTION

[0018] The present invention will be described in detail below with reference to the accompanying drawings: Figures 1 to 3As shown, the present invention includes a lead frame 1 and a lead row 2, the lead row 2 is located around the lead frame 1, a base island 3 is provided in the center of the lead frame 1, and the base island 3 is connected to the side of the lead frame 1 by an inclined connector 4, so that the base island 3 sinks into the lead frame 1; the connectors 4 are distributed on the side of the base island 3 in a surrounding manner, and the adjacent connectors 4 are distributed at equal intervals, at least three glue locking holes 41 are provided on the connector 4, and the adjacent glue locking holes 41 are connected by drainage grooves 42, an IC chip 5 is placed on the front side of the base island 3, and the back side of the base island 3 is a heat dissipation surface 31, and a circle of overflow grooves 6 is provided on the surface of the heat dissipation surface 31.

[0019] The lead frame 1 and the lead row 2 are integrally encapsulated by a plastic body 7. The front side of the plastic body 7 encapsulates the IC chip 5 on the base island 3, and the back side of the plastic body 7 encapsulates the connector 4 and the lead row 2. The heat dissipation surface 31 located on the base island 3 is exposed outside the plastic body 7, and the plane where the back side of the plastic body 7 is located is flush with the heat dissipation surface 31.

[0020] The connector 4 includes a connecting pin 43 and a bent transition connecting block 44. The transition connecting block 44 is integrally formed on the side of the base island 3. One end of the connecting pin 43 is integrally formed on the transition connecting block 44. The other end of the connecting pin 43 is integrally formed on the inner side of the lead frame 1. The connecting pin 43 is flush with the lead frame 1. The transition connecting block 44 is distributed in an inclined manner with the lead frame 1 so that the base island 3 is located below the inner side of the lead frame 1.

[0021] The glue locking holes 41 are distributed at equal intervals and are arranged in sequence along the length direction of the transition connection block 44 , and each glue locking hole 41 is located at a bending corner of the transition connection block 44 .

[0022] The drainage groove 42 is disposed on the back side of the transition connection block 44 , and the drainage groove 42 is disposed along the length direction of the transition connection block 44 and is in a penetrating shape.

[0023] The overflow groove 6 is embedded in the base island 3, the opening of the overflow groove 6 faces the surface of the heat dissipation surface 31, and the overflow groove 6 is close to the side of the base island 3, and the overflow groove 6 is connected end to end; the overflow groove 6 includes four straight groove bodies 61 and four oblique corner groove bodies 62, the four straight groove bodies 61 and the four oblique corner groove bodies 62 are all connected end to end, and the oblique corner groove bodies 62 are located at the corners of the heat dissipation surface 31.

[0024] The four corners of the lead frame 1 are all provided with limiting convex strips 8 , and the limiting convex strips 8 are formed by extending outwards along the lead frame 1 .

[0025] The production process of the present invention is as follows: Figure 4As shown, first, an IC chip 5 is placed on the base island 3 of each lead frame 2 on a whole board, and then, a single lead frame 2, a lead row 2 and an IC chip 5 are integrally encapsulated by a plastic body 7, and then each lead frame 2 of a whole board is cut off. At this time, only the limiting convex strips 8 and the lead row 2 set between adjacent ones need to be cut, and finally, the limiting convex strips 8 and the side of the plastic body 7 are trimmed to be flush. The lead row 2 is basically determined and bent later according to the spacing between the entire LQFP lead frame structure and the welding frame on the integrated circuit board.

[0026] The present invention is not limited to the above-mentioned embodiments. No matter any changes are made in the shape or material composition, any structural design provided by the present invention is a variation of the present invention and should be considered to be within the protection scope of the present invention.

Claims

1. An LQFP lead frame structure, comprising a lead frame (1) and a lead row (2), characterized in that: The lead row (2) is located around the lead frame (1); a base island (3) is provided at the center of the lead frame (1); the base island (3) is connected to the side of the lead frame (1) by an inclined connector (4), so that the base island (3) sinks into the lead frame (1); the connectors (4) are distributed around the side of the base island (3), and adjacent connectors (4) are distributed at equal intervals; at least three glue locking holes (41) are provided on the connector (4), and adjacent glue locking holes (41) are connected by drainage grooves (42); an IC chip (5) is placed on the front side of the base island (3); the back side of the base island (3) is a heat dissipation surface (31), and a circle of overflow grooves (6) is provided on the surface of the heat dissipation surface (31); the connector (4) comprises a connecting foot (43) and a bent transition connection block (44); the transition connection The connecting block (44) is integrally formed on the side of the base island (3), one end of the connecting foot (43) is integrally formed on the transition connecting block (44), the other end of the connecting foot (43) is integrally formed on the inner side of the lead frame (1), and the connecting foot (43) is flush with the lead frame (1), the transition connecting block (44) and the lead frame (1) are distributed in an inclined manner so that the base island (3) is located at the inner lower side of the lead frame (1); the glue locking holes (41) are distributed at equal intervals and are arranged in sequence along the length direction of the transition connecting block (44), and each of the glue locking holes (41) is located at the bending corner of the transition connecting block (44); the drainage groove (42) is arranged on the back side of the transition connecting block (44), and the drainage groove (42) is arranged along the length direction of the transition connecting block (44) and is penetrating.

2. The LQFP lead frame structure according to claim 1, characterized in that: The lead frame (1) and the lead row (2) are integrally encapsulated by a plastic body (7); the front side of the plastic body (7) encapsulates the IC chip (5) on the base island (3), and the back side of the plastic body (7) encapsulates the connector (4) and the lead row (2); a heat dissipation surface (31) located on the base island (3) is exposed outside the plastic body (7), and the plane where the back side of the plastic body (7) is located is flush with the heat dissipation surface (31).

3. The LQFP lead frame structure according to claim 1, characterized in that: The overflow groove (6) is embedded in the base island (3), the opening of the overflow groove (6) faces the surface of the heat dissipation surface (31), and the overflow groove (6) is close to the side of the base island (3), and the overflow groove (6) is connected end to end.

4. The LQFP lead frame structure according to claim 3, characterized in that: The overflow trough (6) comprises four straight trough bodies (61) and four oblique angle trough bodies (62), the four straight trough bodies (61) and the four oblique angle trough bodies (62) are connected end to end, and the oblique angle trough bodies (62) are located at the corners of the heat dissipation surface (31).

5. The LQFP lead frame structure according to claim 1, characterized in that: Limiting convex strips (8) are provided at the four end corners of the lead frame (1), and the limiting convex strips (8) are formed by extending outwards along the lead frame (1).

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