Lead frame

Abstract

The utility model provides a lead frame, which is applied to the technical field of lead frames, and is characterized in that the lead frame is used for being connected with a chip and comprises a structural frame and a radiating fin which is fixed on the structural frame and is used for bearing the chip; a lead terminal which is positioned on the radiating fin and is electrically connected with the chip through a lead is fixed on the structural frame; a welding area for welding a lead is arranged on the lead terminal; a bonding layer for isolating and fixing the lead terminal and the radiating fin together is arranged between the lead terminal and the radiating fin; the utility model has the technical effects that the positioning of the welding area can be better realized, and the deviation of the lead terminal in the chip welding process or the injection molding plastic body packaging process is avoided; and the connection stability of the chip and the quality of a product are further improved.

Description

Technical Field

[0001] The utility model relates to the technical field of lead frames, in particular to a lead frame. Background Art

[0002] As the chip carrier of integrated circuits, the lead frame is a key structural component that uses bonding materials (gold wire, aluminum wire, copper wire) to achieve electrical connection between the internal circuit lead ends of the chip and the external leads to form an electrical circuit. It serves as a bridge to connect to external wires. Lead frames are required in most semiconductor integrated blocks and are an important basic material in the electronic information industry.

[0003] At present, the Chinese utility model patent with publication number CN113838828A discloses a high-power integrated circuit lead frame structure, including a heat sink for placing chips and a lead sheet where the leads connecting the chips are located; the heat sink and the lead sheet are fixedly connected by riveting, and the middle of the lead sheet has a cavity and a welding area located outside the cavity; the back of the heat sink is the heat dissipation area, and the middle of the front of the heat sink is the chip mounting area, and four rivets are respectively provided at the four corners of the chip mounting area; four rivet holes are provided in the middle of the lead sheet, which are riveted to the four rivets on the heat sink respectively, and the two main bodies of the lead frame can be firmly combined after four-point riveting by a precision riveting mold.

[0004] However, the welding area in the lead sheet on this lead frame structure is suspended relative to the heat sink. During the process of welding the wires or the process of injection molding the plastic body for packaging, a special fixture is required to position the welding area in the lead sheet. Otherwise, the welding area is prone to shifting up and down or left and right, which will affect the connection stability of the chip and the quality of the product. Utility Model Content

[0005] The purpose of the utility model is to provide a lead frame, which has the advantage of better positioning the welding area and avoiding the deviation of the lead terminal during the chip welding process or the injection molding plastic body packaging process; further improving the connection stability of the chip and the quality of the product.

[0006] In order to achieve the above purpose and other related purposes, the utility model provides the following technical solutions:

[0007] A lead frame, used for connecting a chip, comprises a structural frame and a heat sink fixed on the structural frame and used for carrying the chip;

[0008] The structural frame is fixed with a lead terminal located on the heat sink and electrically connected to the chip through a lead wire; the lead terminal is provided with a welding area for welding the lead wire;

[0009] An adhesive layer is arranged between the lead terminal and the heat sink to isolate and fix the lead terminal and the heat sink together.

[0010] Through the above technical solution, the heat sink is fixedly connected to the structural frame, the chip is fixed on the heat sink, and the chip is connected to the lead terminal through the lead wire; the lead terminal is fixedly connected to the heat sink through the adhesive layer, so that the heat sink and the lead terminal are fixed, the welding area is better positioned, and the flatness of the welding area is ensured. In the process of welding the chip or the process of encapsulating the injection molded plastic body, the lead terminal is prevented from being offset in the up and down or front and back and left and right directions, thereby further improving the connection stability of the chip and the quality of the product.

[0011] In an embodiment of the present invention, the structural frame is riveted to the heat sink.

[0012] In one embodiment of the utility model, a chip mounting area is provided in the middle of the heat sink; a rivet column is fixed on the heat sink located outside the chip mounting area;

[0013] A riveting terminal is fixedly arranged on the structural frame, and a riveting hole for riveting with a riveting column is opened on the riveting terminal.

[0014] In an embodiment of the present invention, an expansion groove is formed in the middle of the riveting column.

[0015] In an embodiment of the present invention, the expansion groove is formed by being recessed downward from the upper surface of the riveting column, and the cross section of the expansion groove is a trapezoidal structure that is wide at the top and narrow at the bottom.

[0016] Through the above technical scheme, during the process of fixing the riveted column and the riveted terminal, the riveted column passes through the riveting hole, enters the expansion groove through the jig to stretch the riveted column outward, and contacts the riveted terminal outward, thereby reducing the matching gap between the riveted column and the riveted hole after riveting, and then more accurately realizes the fixation and positioning between the heat sink and the riveted terminal. During the process of fixing and matching the chip and the heat sink or the subsequent plastic body injection molding for packaging, the position displacement of the heat sink relative to the riveted terminal is avoided, thereby further improving the connection stability of the chip and ensuring the quality of the product.

[0017] In one embodiment of the utility model, the riveted terminal includes a sinking plate fixedly connected to the structural frame and a fixing plate fixedly connected to the sinking plate, and the riveting hole is opened on the fixing plate;

[0018] The setting height of the fixing plate is lower than the setting height of the lead terminal.

[0019] In an embodiment of the present invention, the chip is fixed on a heat sink, and an upper end surface of the chip fixed on the heat sink is flush with the welding area.

[0020] Through the above technical solution, the sinking plate is used to sink the fixed plate so that the setting height of the fixed plate is lower than the setting height of the lead terminal; thereby forming a height difference between the welding area and the fixed plate, and then adjusting the height of the welding area to be flush with the upper surface of the chip, so that the two ends of the lead connecting the welding area and the chip are always maintained in the same horizontal plane, thereby shortening the length of the lead, which can not only save the cost of the lead, but also reduce the signal transmission path and improve the quality of the product.

[0021] In one embodiment of the present invention, the adhesive layer is a cured insulating glue; the adhesive layer is bonded to the surface of the lead terminal on the side opposite to the welding area.

[0022] In one embodiment of the present invention, an undercut groove is provided on the heat sink below the lead terminal, and the insulating glue is filled into the undercut groove.

[0023] Through the above technical solution, the bonding layer is formed after the filled insulating glue is cured; the heat sink is provided with an undercut groove for accommodating the insulating glue, and the undercut groove is used to increase the bonding force between the glue and the heat sink to prevent the glue from falling off the heat sink 2.

[0024] In an embodiment of the present invention, the surfaces of the chip attaching area and the welding area are plated with silver.

[0025] Through the above technical solution, the surface of the welding area is silver-plated to improve the welding performance, and the surface area of ​​the chip bonding area is silver-plated to increase the bonding force between the heat sink and the chip.

[0026] As described above, a lead frame of the utility model has the following beneficial effects:

[0027] 1. During the riveting and fixing process of the riveted column and the riveted terminal, the riveted column passes through the riveting hole, enters the expansion groove through the jig to stretch the riveted column outward, and contacts the riveted terminal outward, thereby reducing the matching gap between the riveted column and the riveted hole after riveting, realizing the fixation and positioning between the heat sink and the riveted terminal, and also realizing the precise positioning of the heat sink and the lead terminal.

[0028] 2. The sinking plate is used to sink the fixed plate, so as to form a height difference between the welding area and the fixed plate, and then adjust the height of the welding area to be flush with the upper surface of the chip, so that the two ends of the lead connecting the welding area and the chip are always kept at the same horizontal plane, thereby shortening the length of the lead, which can not only save the cost of the lead, but also shorten the signal transmission path;

[0029] 3. The lead terminal is fixedly connected to the heat sink through an adhesive layer to achieve fixation between the heat sink and the lead terminal, better position the welding area, ensure the flatness of the welding area, and prevent the lead terminal from shifting up and down or forward and backward or left and right during the chip welding process or the injection molding plastic body packaging process, further improving the chip connection stability and product quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the overall structure of an embodiment of the utility model;

[0031] Figure 2 This is a schematic diagram of the connection relationship between the structural frame and the heat sink of the embodiment of the utility model;

[0032] Figure 3 It is a schematic diagram of the structure of the heat sink of an embodiment of the utility model;

[0033] Figure 4 It is a schematic diagram of the structure of the expansion slot of an embodiment of the utility model;

[0034] Figure 5 It is a structural schematic diagram of the undercut groove of an embodiment of the utility model.

[0035] Figure numerals: 1. structural frame; 2. heat sink; 3. chip; 4. lead; 5. lead terminal; 6. welding area; 7. adhesive layer; 8. chip mounting area; 9. rivet column; 10. rivet terminal; 11. rivet hole; 12. expansion groove; 101. sinking plate; 102. fixing plate; 15. undercut groove. DETAILED DESCRIPTION

[0036] The following is a description of the implementation of the present invention by means of specific embodiments. People familiar with the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0037] See also Figures 1 to 5It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings in this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the utility model, so they have no substantial technical significance. Any modification of the structure, change in the proportion relationship, or adjustment of the size should still fall within the scope of the technical content disclosed by the utility model without affecting the effects and purposes that can be achieved by the utility model. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description, and are not used to limit the scope of the implementation of the utility model. The change or adjustment of their relative relationship should also be regarded as the scope of the implementation of the utility model without substantially changing the technical content.

[0038] See also Figure 1 , the utility model provides a lead frame, which can be used to install a chip 3, and is packaged by an injection-molded plastic body to form a chip packaging assembly;

[0039] The lead frame includes a structural frame 1 and a heat sink 2 fixed on the structural frame 1, and the chip 3 is fixedly mounted on the heat sink 2. The structural frame 1 and the chip 3 are welded through a lead 4 (gold wire) to achieve the purpose of electrical connection. In this embodiment, the structural frame 1 and the heat sink 2 are riveted together;

[0040] A lead terminal 5 is fixed on the structural frame 1, and a welding area 6 for welding the lead wire 4 is provided on the lead terminal 5; the welding area 6 is provided on the upper surface of the lead terminal 5 and the surface is silver-plated to improve welding performance;

[0041] An adhesive layer 7 is provided between the lead terminal 5 and the heat sink 2 , and the adhesive layer 7 is used to isolate and fix the lead terminal and the heat sink together.

[0042] See also Figure 2 , Figure 3 and Figure 4 In this embodiment, the heat sink 2 is a rectangular plate made of metal, and the middle part above the heat sink 2 is a chip mounting area 8. The surface of the chip mounting area 8 is silver-plated, so as to increase the bonding force between the heat sink 2 and the chip 3; a rivet column 9 is integrally stamped on the heat sink 2 outside the chip mounting area 8; wherein the heat sink 2 is integrally stamped with a rivet column 9 near the four corners, and an expansion groove 12 is opened in the middle of the rivet column 9, and the expansion groove 12 is formed by being recessed downward from the upper surface of the rivet column 9, and is in an inverted truncated cone structure that is wide at the top and narrow at the bottom, that is, the cross section of the expansion groove 12 is a trapezoidal structure that is wide at the top and narrow at the bottom;

[0043] Four riveted terminals 10 riveted to the riveted columns 9 are integrally formed on the structural frame 1, so as to fix the structural frame 1 and the heat sink 2 together to achieve relatively accurate positioning of the two during the manufacturing process. Riveted holes 11 are provided on the riveted terminals 10; the riveted terminals 10 include a sinking plate 101 integrally formed with the structural frame 1 and a fixing plate 102 integrally formed with the sinking plate 101, the sinking plate 101 is tilted downward, the bottom of the fixing plate 102 contacts the top of the heat sink 2, and the riveted holes 11 are provided on the fixing plate 102;

[0044] The sinking plate 101 is tilted downward so that the setting height of the fixing plate 102 is lower than the setting height of the lead terminal 5, thereby forming a height difference between the welding area and the fixing plate 102, and then adjusting the height of the welding area 6 to be flush with the upper end surface of the chip 3, so that the two ends of the lead 4 connecting the welding area 6 and the chip 3 are always maintained in the same horizontal plane.

[0045] See also Figure 1 , Figure 2 and Figure 5 A plurality of lead terminals 5 are integrally formed on the structural frame 1 located on both sides of the heat sink 2. The bottom of the lead terminal 5 is spaced from the top of the heat sink 2 to avoid overlapping and short-circuiting the lead terminal 5 and the heat sink 2. Insulating glue is filled between the heat sink 2 and the lead terminal 5. After the insulating glue is cured, an adhesive layer 7 is formed, thereby separating and fixing the lead terminal 5 and the heat sink 2 from each other.

[0046] An undercut groove 15 is provided on the heat sink 2 below the lead terminal 5 ; the undercut groove 15 is used to receive insulating glue, thereby increasing the bonding force between the glue and the heat sink 2 and preventing the glue from falling off the heat sink 2 .

[0047] A brief description of the use process: the structural frame 1 is installed on the heat sink 2, the rivet column 9 passes through the rivet hole 11, and enters the expansion groove 12 through the fixture. The expansion groove 12 is forced to open the rivet column 9 outward, so that the rivet column 9 contacts the rivet terminal 10 outward, and the matching gap between the rivet column 9 and the rivet hole 11 after riveting is reduced; then the insulating glue is filled in the gap between the lead terminal 5 and the heat sink 2, and the insulating glue is cured to form an adhesive layer 7 that fixes the lead terminal 5 and the heat sink 2 together; then the chip 3 is attached to the chip attachment area 8 on the heat sink 2, and finally the lead 4 connecting the chip 3 is welded to the welding area 6 of the lead terminal 5.

[0048] In summary, in the utility model, the jig stamping expansion groove 12 can reduce the matching gap between the riveted column 9 and the riveted hole 11 after riveting, thereby more accurately achieving the fixation and positioning between the heat sink 2 and the riveted terminal 10; the lead terminal 5 is fixedly connected to the heat sink 2 through the adhesive layer 7 to achieve the fixation between the heat sink 2 and the lead terminal 5, and the adhesive layer 7 is bonded to the surface of the lead terminal 5 on the side opposite to the welding area 6 (that is, the lower surface position of the lead terminal 5 corresponding to the welding area 6), so as to better position the welding area 6 and ensure the flatness of the welding area 6. In the process of welding the chip 3 or the process of encapsulating the injection molded plastic body, the lead terminal 5 is prevented from being offset in the up and down or front and back left and right directions, thereby further improving the connection stability of the chip 3 and the quality of the product. Therefore, the utility model effectively overcomes the various shortcomings of the prior art and has a high industrial utilization value.

[0049] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the technology may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed in the present invention shall still be covered by the claims of the present invention.

Claims

1. A lead frame for connecting a chip (3), characterized in that: It comprises a structural frame (1) and a heat sink (2) fixed on the structural frame (1) and used for carrying a chip (3); A lead terminal (5) is fixed on the structural frame (1) and is located on the heat sink (2) and is electrically connected to the chip (3) via a lead wire (4); a welding area (6) for welding the lead wire (4) is provided on the lead terminal (5); An adhesive layer (7) is provided between the lead terminal (5) and the heat sink (2) to isolate and fix the lead terminal (5) and the heat sink together.

2. A lead frame according to claim 1, characterized in that: The structural frame (1) is riveted to the heat sink (2).

3. A lead frame according to claim 2, characterized in that: A chip mounting area (8) is provided in the middle of the heat sink (2); a rivet column (9) is fixed on the heat sink (2) outside the chip mounting area (8); A riveting terminal (10) is fixedly arranged on the structural frame (1), and a riveting hole (11) for riveting to a riveting column (9) is provided on the riveting terminal (10).

4. A lead frame according to claim 3, characterized in that: An expansion groove (12) is provided in the middle of the riveting column (9).

5. A lead frame according to claim 4, characterized in that: The expansion groove (12) is formed by being recessed downward from the upper surface of the riveting column (9), and the cross section of the expansion groove (12) is a trapezoidal structure that is wide at the top and narrow at the bottom.

6. The lead frame according to claim 3, characterized in that: The riveted terminal (10) comprises a sinking plate (101) fixedly connected to the structural frame (1) and a fixing plate (102) fixedly connected to the sinking plate (101), and the riveting hole (11) is provided on the fixing plate (102); The setting height of the fixing plate (102) is lower than the setting height of the lead terminal (5).

7. The lead frame according to claim 6, characterized in that: The chip (3) is fixed on the heat sink (2), and the upper end surface of the chip (3) fixed on the heat sink is flush with the welding area (6).

8. The lead frame according to claim 1, characterized in that: The bonding layer (7) is a cured insulating glue; the bonding layer (7) is bonded to the surface of the lead terminal (5) on the side opposite to the welding area (6).

9. The lead frame according to claim 8, characterized in that: An undercut groove (15) is provided on the heat sink (2) below the lead terminal (5), and the insulating glue is filled into the undercut groove (15).

10. The lead frame according to claim 3, characterized in that: The surfaces of the chip attaching area (8) and the welding area (6) are plated with silver.

Images