TO247 packaging structure capable of increasing heat dissipation area

Abstract

The TO247 packaging structure comprises a lead frame and a plastic package body, the lead frame is provided with an upper overflow isolation groove and a lower overflow isolation groove, the upper overflow isolation groove is located above the lower overflow isolation groove, the upper overflow isolation groove and the lower overflow isolation groove are both of U-shaped structures with opposite openings, and the plastic package body is provided with a plurality of grooves. The upper overflow separation groove and the lower overflow separation groove are arranged on the substrate, so that a base island area is formed between the upper overflow separation groove and the lower overflow separation groove, the front surface of the base island area is used for mounting a chip, the back surface of the base island area is provided with a cooling fin, the front end of the plastic package body completely wraps the chip carrying area, the back end of the plastic package body is connected with the periphery of the cooling fin, and the surface of the cooling fin exposed outside the plastic package body is continuous.

Description

Technical Field

[0001] This utility model relates to the field of semiconductor packaging technology, specifically to a TO247 packaging structure that increases the heat dissipation area. Background Technology

[0002] The leadframe is the chip carrier of an integrated circuit. In industrial manufacturing, it forms a semiconductor device by mounting chips and packaging them. Currently, the conventional TO-247 package structure includes a leadframe, a molding compound, and a heat sink. The front end of the molding compound completely covers the chip carrier area, and the rear end of the molding compound connects to the perimeter of the heat sink, exposing the surface of the heat sink. To dissipate heat from the chip packaged on the leadframe, corresponding circular holes for the heat sink are generally provided on both the leadframe and the heat sink. Screws pass through two of these holes to fix the heat sink to the leadframe. In this case, the circular holes are located on the exposed area of ​​the heat sink, resulting in a lack of continuity on the surface of the heat sink exposed outside the molding compound. Therefore, this invention considers changing the fixing method between the heat sink and the leadframe to increase the surface area of ​​the heat sink exposed outside the molding compound, thereby improving the heat dissipation effect. Summary of the Invention

[0003] The purpose of this invention is to provide a TO247 package structure that increases the heat dissipation area. This is mainly achieved by changing the fixing method between the heat sink and the lead frame to increase the heat dissipation area, making the surface of the heat sink exposed outside the plastic package continuous, thereby solving the heat dissipation problem of large chip packages.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following solution:

[0005] A TO247 package structure with increased heat dissipation area includes a lead frame and a molding compound. The lead frame has an upper overflow groove and a lower overflow groove, with the upper overflow groove located above the lower overflow groove. Both the upper and lower overflow grooves are U-shaped structures with openings facing each other, forming a base island area between them. The front side of the base island area is used for chip mounting, and a heat sink is provided on the back side of the base island area. The front end of the molding compound completely covers the die area, and the rear end of the molding compound is connected to the periphery of the heat sink. The surface of the heat sink exposed outside the molding compound is continuous.

[0006] Furthermore, a heat sink fixing assembly is provided on the rear end of the molding compound. The heat sink fixing assembly includes a first bending portion symmetrically arranged on both sides of the heat sink. The first bending portion extends from the molding compound and then bends from the corresponding sides of the heat sink toward the surface of the heat sink.

[0007] Furthermore, the heat sink fixing assembly also includes a second bending portion disposed below the heat sink. The second bending portion extends from the molding compound and then bends from below the corresponding heat sink towards the surface of the heat sink. The two ends of the second bending portion are respectively connected to the corresponding first bending portion.

[0008] Furthermore, both the first bending portion and the second bending portion include a vertical portion and a horizontal portion connected in sequence. The vertical portion is vertically connected to the molding compound, and the horizontal portion is arranged parallel to the heat sink. The inner side of the horizontal portion is in close contact with the surface of the heat sink.

[0009] Furthermore, a round hole is provided on the second bending part, and a fixing hole with the same shape as the round hole is also provided on the heat sink located inside the second bending part. The round hole and the fixing hole are connected by bolts.

[0010] Furthermore, a pressing area for abutting the top rod is formed in the upper part of the lower overflow groove near the upper overflow groove, and the pressing area is located outside the lower overflow groove.

[0011] Furthermore, the lower overflow groove includes two opposing inner groove sections, which are located inside the two tableting areas respectively.

[0012] Furthermore, the lower overflow trough also includes an outer trough section, which is closer to the edge of the frame body than the inner trough section, and the lower ends of the two inner trough sections are bent outward and connected to the two ends of the outer trough section respectively.

[0013] Furthermore, the upper end of the inner groove section extends to the upper overflow groove and forms a partition with the upper overflow groove.

[0014] Furthermore, the lead frame includes a pin area located below the base island area, the pin area including at least three pins one end of which is connected to the base island area.

[0015] The beneficial effects of this utility model are:

[0016] This invention provides a TO247 package structure with an increased heat dissipation area. The main improvement is that the existing technology of fixing the heat dissipation area is replaced by fixing it around the perimeter of the heat dissipation area. A first and second bending portion on the molding compound bends the heat sink towards its surface, fixing it to both sides and below. This not only ensures the continuity of the heat sink surface exposed outside the molding compound, but also significantly increases the heat dissipation area compared to existing technologies. While solving the heat dissipation problem, it also ensures the heat sink is fixed, allowing the chip packaged on the lead frame to dissipate heat through the heat sink. Attached Figure Description

[0017] Figure 1This is a front view of the conventional TO-247 package structure in Embodiment 1 of this utility model;

[0018] Figure 2 This is a schematic diagram of the back of a conventional TO-247 package structure in Embodiment 1 of this utility model;

[0019] Figure 3 This is a front view of a TO247 package structure with an increased heat dissipation area according to Embodiment 1 of this utility model;

[0020] Figure 4 This is a schematic diagram of the back of a TO247 package structure with an increased heat dissipation area according to Embodiment 1 of this utility model;

[0021] Figure 5 This is a horizontal cross-sectional view of a TO247 package structure with an increased heat dissipation area according to Embodiment 1 of this utility model.

[0022] Figure 6 This is a schematic diagram of the lead frame structure in a TO247 package structure with an increased heat dissipation area according to Embodiment 1 of this utility model;

[0023] Explanation of reference numerals in the attached drawings: 1-lead frame, 2-molded body, 3-upper overflow groove, 4-lower overflow groove, 40-inner groove section, 41-outer groove section, 5-base island area, 6-heat sink, 7-first bend, 8-second bend, 9-round hole, 10-round hole of heat sink, 11-pressing area, 12-pin. Detailed Implementation

[0024] To enable those skilled in the art to better understand the technical solution of this utility model, the present utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments, but the embodiments of this utility model are not limited thereto.

[0025] In the description of this utility model, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "longitudinal", "lateral", "horizontal", "inner", "outer", "front", "rear", "top", "bottom", 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 utility model product is in use. They are only for the convenience of describing this utility model 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. Therefore, they should not be construed as limitations on this utility model.

[0026] In the description of this utility model, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set up," "have," "install," "connect," and "connect" 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 utility model based on the specific circumstances.

[0027] The present invention will now be described in detail with reference to the accompanying drawings and embodiments:

[0028] Example 1

[0029] like Figure 1 , Figure 2 As shown, the conventional TO-247 package structure includes a lead frame 1, a molding compound 2, and a heat sink 6. The lead frame 1 includes a heat sink 6, a carrier area, and pin 12 areas connected sequentially from top to bottom. The front end of the molding compound 2 completely covers the carrier area, and the rear end of the molding compound 2 is connected to the perimeter of the heat sink 6. Therefore, from the back side of the package structure, the surface of the heat sink 6 is exposed. Since screws are commonly used to fix the heat sink 6 to the molding compound 2 in the prior art, heat sink circular holes 9 are provided on both the molding compound 2 and the heat sink 6 so that the screws can pass through the two circular holes 9 in sequence to achieve fixation. At this time, for the heat sink 6, the heat sink circular holes 10 occupy the heat dissipation area of ​​the heat sink 6, thus requiring the screws to pass through the heat dissipation area to fix the heat sink 6.

[0030] Therefore, this utility model chooses to change the fixing method between the heat sink 6 and the molding compound 2. By using the first bending part 7 and the second bending part 8 provided on the molding compound 2, the heat sink 6 is bent towards the surface of the heat sink 6, and the heat sink 6 is fixed on both sides and the bottom. This not only ensures that the surface of the heat sink 6 exposed outside the molding compound 2 is continuous, that is, the heat dissipation area is increased compared with the prior art, but also ensures that the heat sink 6 is fixed so that the chip packaged on the lead frame 1 can dissipate heat through the heat sink 6.

[0031] like Figure 3-5As shown in this embodiment, the TO247 package structure with increased heat dissipation area includes a lead frame 1 and a molding compound 2. The lead frame 1 has an upper overflow groove 3 and a lower overflow groove 4. The upper overflow groove 3 is located on the lower overflow groove 4, and both the upper overflow groove 3 and the lower overflow groove 4 are U-shaped structures with openings facing each other, forming a base island area 5 between the upper overflow groove 3 and the lower overflow groove 4. The front side of the base island area 5 is used for chip mounting, and a heat sink 6 is provided on the back side of the base island area 5. The front end of the molding compound 2 completely covers the substrate area, and the rear end of the molding compound 2 is connected to the periphery of the heat sink 6. The surface of the heat sink 6 exposed outside the molding compound 2 is continuous. Compared with the prior art, the heat dissipation area is increased.

[0032] Furthermore, a heat sink 6 fixing assembly is provided on the rear end of the encapsulation body 2. The heat sink 6 fixing assembly includes a first bending portion 7 symmetrically arranged on both sides of the heat sink 6. The first bending portion 7 extends from the encapsulation body 2 and then bends from the corresponding sides of the heat sink 6 toward the surface of the heat sink 6.

[0033] The rear end of the molding compound 2 is provided with a second bending portion 8 located below the heat sink 6. The second bending portion 8 extends from the molding compound 2 and then bends from below the corresponding heat sink 6 to the surface of the heat sink 6. The two ends of the second bending portion 8 are respectively connected to the corresponding first bending portion 7.

[0034] As a specific embodiment of the above, the first bending portion 7 and the second bending portion 8 each include a vertical portion and a horizontal portion connected in sequence. The vertical portion is vertically connected to the molding compound 2, and the horizontal portion is arranged parallel to the heat sink 6. The inner side of the horizontal portion is in close contact with the surface of the heat sink 6. In the prior art, the rear end of the molding compound 2 is connected to the periphery of the heat sink 6. That is, after the encapsulation is completed, the back of the encapsulation structure, that is, on the same horizontal plane, is connected to the sides and bottom of the heat sink 6 by a portion of the molding compound 2. In this embodiment, it is only necessary to provide the first bending portion 7 and the second bending portion 8 close to the heat sink 6 on the surface of a portion of the molding compound 2. The inner sides of the first bending portion 7 and the second bending portion 8 are in close contact with the surface of the heat sink 6. However, the size of the first bending portion 7 and the second bending portion 8 does not need to be very large. The two first bending portions 7 with symmetrical properties can ensure the fixing effect on the heat sink 6.

[0035] Furthermore, a round hole 9 can be provided on the horizontal part of the second bending part 8, and a fixing hole with the same as the round hole 9 can also be provided on the heat sink 6 located inside the second bending part 8. The round hole 9 and the fixing hole are connected by bolts. At this time, the heat dissipation area of ​​the exposed heat sink 6 is not occupied.

[0036] Example 2

[0037] like Figure 6As shown, based on Embodiment 1, the TO247 package structure with increased heat dissipation area includes a lead frame 1 and a molding compound 2. The lead frame 1 has an upper overflow groove 3 and a lower overflow groove 4. The upper overflow groove 3 is located on the lower overflow groove 4, and both the upper overflow groove 3 and the lower overflow groove 4 are U-shaped structures with openings facing each other, so that a base island area 5 is formed between the upper overflow groove 3 and the lower overflow groove 4. The front side of the base island area 5 is used for chip mounting.

[0038] When the fixing method between the heat sink 6 and the molding compound 2 is changed in Embodiment 1, the chip carrier area of ​​the base island region 5 can also be expanded. The base island region 5 can be expanded by adjusting the overflow groove at the edge, which can meet the packaging requirements of large chips and increase product power. At the same time, the increased heat dissipation area of ​​the heat sink 6 also ensures the heat dissipation effect of the product under high power.

[0039] The lower overflow groove 4 has a pressing area 11 formed at the upper part near the upper overflow groove 3 for abutting the mold ejector. The pressing area 11 is located outside the lower overflow groove 4. When injection molding forms a plastic seal, the mold ejector abuts against the pressing area 11 to fix the frame body. During the injection molding process, since the pressing area 11 is isolated from the upper overflow groove 3 and the lower overflow groove 4, the plastic sealant will not enter the pressing area 11 and will enter between the mold ejector and the pressing area 11. This reduces the technical problem that the plastic sealant will enter the overflow groove and solidify at the positioning groove, making it difficult to remove.

[0040] In this process, after encapsulation and demolding, the pressing area 11 forms the bottom of the positioning groove, which is an exposed plane, making it more aesthetically pleasing. It also eliminates the need to remove the molding compound, allowing the frame to be partially exposed and directly exposed to the air, thus providing a certain degree of heat dissipation.

[0041] As a specific embodiment of the above, the two ends of the upper overflow groove 3 are bent downwards. The pressing area 11 is symmetrically arranged in two places above the frame body. The lower overflow groove 4 includes two inner groove sections 40 and outer groove sections 41 arranged opposite to each other. The outer groove section 41 is closer to the edge of the frame body than the inner groove section 40. The lower ends of the two inner groove sections 40 are bent outwards and connected to the two ends of the outer groove section 41 respectively. The other end of the inner groove section 40 is located inside the pressing area 11, which can form a barrier for the molding compound to flow from the pressing area 11 to the two inner grooves, reducing the problem of molding compound seeping inwards. The inner groove section 40 improves the bonding strength with the molding compound to form a package. The outer groove section 41 is closer to the edge of the frame body than the inner groove section 40, which can improve the bonding strength between the entire frame and the package at the edge.

[0042] In another embodiment, the frame body includes a pin 12 area located below the second chip mounting slot, the pin 12 area including at least three pins 12, one end of which is connected to the first chip mounting slot and the second chip mounting slot. The advantage of using the preferred embodiment described above is that it utilizes the pins 12 to drive and control the MOSFET, and provides necessary protection functions.

[0043] Among them, MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor), also known as metal-oxide-semiconductor field-effect transistor, is a semiconductor device that can be widely used in analog and digital circuits.

[0044] Pin 12 is divided into a positive power supply pin, a negative power supply pin, a gate pin, and other pins, such as the line voltage detection (L) pin and the external current limit (X) pin. Among them, the positive power supply pin is responsible for providing the current and voltage path; the negative power supply pin is connected to the load or other circuit parts; the gate pin is the input pin of the error amplifier and feedback current, used to control the current flow.

[0045] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of this utility model, and the utility model is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of this utility model, and these modifications and improvements are also considered to be within the protection scope of this utility model.

Claims

1. A TO247 package structure for increasing heat dissipation area, comprising a lead frame (1) and a molding compound (2), wherein the lead frame (1) has an upper overflow groove (3) and a lower overflow groove (4), the upper overflow groove (3) is located on the lower overflow groove (4), and both the upper overflow groove (3) and the lower overflow groove (4) are U-shaped structures with openings facing each other, forming a base island area (5) between the upper overflow groove (3) and the lower overflow groove (4), characterized in that, The front side of the base island area (5) is used for mounting chips, and a heat sink (6) is provided on the back side of the base island area (5). The front end of the molding compound (2) completely covers the carrier area, and the rear end of the molding compound (2) is connected to the periphery of the heat sink (6). The surface of the heat sink (6) exposed outside the molding compound (2) is continuous. A heat sink (6) fixing assembly is provided on the rear end of the encapsulation body (2). The heat sink (6) fixing assembly includes a first bending portion (7) symmetrically arranged on both sides of the heat sink (6). The first bending portion (7) extends from the encapsulation body (2) and then bends from both sides of the corresponding heat sink (6) toward the surface of the heat sink (6). The heat sink (6) fixing assembly also includes a second bending portion (8) disposed below the heat sink (6). The second bending portion (8) extends from the encapsulation body (2) and then bends from below the corresponding heat sink (6) toward the surface of the heat sink (6). The two ends of the second bending portion (8) are respectively connected to the corresponding first bending portion (7).

2. The TO247 package structure with increased heat dissipation area according to claim 1, characterized in that, The first bending portion (7) and the second bending portion (8) each include a vertical portion and a horizontal portion connected in sequence. The vertical portion is vertically connected to the encapsulation body (2), and the horizontal portion is arranged parallel to the heat sink (6). The inner side of the horizontal portion is in close contact with the surface of the heat sink (6).

3. The TO247 package structure with an increased heat dissipation area according to claim 1, characterized in that, The second bend (8) is provided with a round hole (9), and the heat sink (6) located in the second bend (8) is also provided with a fixing hole that is the same as the round hole (9). The round hole (9) and the fixing hole are connected by bolts.

4. The TO247 package structure with an increased heat dissipation area according to claim 1, characterized in that, The lower overflow trough (4) has a pressing area (11) for abutting the top rod formed on the upper part near the upper overflow trough (3), and the pressing area (11) is located outside the lower overflow trough (4).

5. The TO247 package structure with an increased heat dissipation area according to claim 4, characterized in that, The lower overflow trough (4) includes two opposing inner trough sections (40), which are located inside the two tableting areas (11) respectively.

6. The TO247 package structure with an increased heat dissipation area according to claim 5, characterized in that, The lower overflow trough (4) also includes an outer trough section (41), which is closer to the edge of the frame body than the inner trough section (40), and the lower ends of the two inner trough sections (40) are bent outward and connected to the two ends of the outer trough section (41) respectively.

7. The TO247 package structure with an increased heat dissipation area according to claim 5, characterized in that, The upper end of the inner groove section (40) extends to the upper overflow groove (3) and forms a partition with the upper overflow groove (3).

8. The TO247 package structure with increased heat dissipation area according to claim 1, characterized in that, The lead frame (1) includes a pin (12) area located below the base island area (5), the pin (12) area including at least three pins (12) with one end connected to the base island area (5).

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