A top heat dissipation packaging structure based on a TO-220 frame

Abstract

This utility model relates to the field of semiconductor device packaging technology, specifically to a top heat dissipation packaging structure based on a TO-220 frame. It includes a heat sink and a molding compound, with the molding compound located at the bottom of the heat sink. The heat sink is rectangular and has stress relief holes, including a base hole and extended stress relief holes. The extended stress relief holes are located at the bottom of the base hole and communicate with it. The maximum horizontal distance between the extended stress relief holes is greater than the maximum horizontal distance between the base holes. The heat sink is bent horizontally along the interior of the extended stress relief holes. A specific stress relief hole structure is designed at the center of the heat sink, which fundamentally eliminates the enormous mechanical stress generated during bending.

Description

Technical Field

[0001] This utility model relates to the field of semiconductor device packaging technology, specifically to a top heat dissipation packaging structure based on a TO-220 frame. Background Technology

[0002] TO-220 and TO-263 are two widely used packaging types in the power semiconductor field. TO-220 is a through-hole package where the heatsink is perpendicular to the lead plane. During installation, it requires an insulating sheet and screws to be fixed to the heatsink, resulting in cumbersome assembly processes, large size, and significant PCB space consumption. TO-263 is a surface-mount package where the heatsink and leads are on the same plane, resulting in a smaller size and easier automated placement. However, conventional TO-263 packages suffer from poor heat dissipation due to the low thermal conductivity of the PCB board, limiting the performance of high-power devices. Furthermore, using a metal substrate to address heat dissipation increases system costs. Existing technology involves bending the heatsink of the TO-220 leadframe to create a surface-mount top-heat-dissipating package similar to TO-263. However, directly bending the heatsink generates significant mechanical stress at the bend root, which can easily lead to product delamination failure, reliability issues, and low yield. Utility Model Content

[0003] The technical problem to be solved by this utility model is to address the issues of high mechanical stress and easy delamination failure in the existing technology when bending and modifying the TO-220 frame into a patch top heat dissipation package. This utility model provides a top heat dissipation package structure that is simple in structure, can effectively release stress, and has high reliability.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A top heat dissipation package structure based on a TO-220 frame includes a heat sink and a molding compound, the molding compound being located at the bottom of the heat sink; the heat sink is rectangular, and has a base hole and an extended stress relief hole, the extended stress relief hole being located at the bottom of the base hole, the base hole and the extended stress relief hole being connected, the maximum horizontal distance between the extended stress relief hole being greater than the maximum horizontal distance between the base hole, and the heat sink being bent along the horizontal direction inside the extended stress relief hole.

[0005] Existing heat sinks have a circular hole. During the finning and forming process, the heat sink often needs to be bent, typically along a horizontal line slightly below the horizontal center line of the circular hole. Due to the large bending width, the mechanical stress during bending is too high, which can easily lead to product delamination failure. This invention bends along the horizontal direction inside the stress-relieving hole, which has a larger horizontal distance, resulting in a smaller bending width than in the prior art. This reduces the mechanical stress on the heat sink during bending, greatly reducing the risk of delamination of the encapsulated body, and significantly improving product yield and long-term reliability.

[0006] Preferably, the basic hole is a semi-circular stress relief hole; the extended stress relief hole is a rectangular stress relief hole or a double-ended rounded rectangular stress relief hole.

[0007] Preferably, the heat sink is bent along the horizontal centerline of the extended stress relief hole, and the bent heat sink and the bent pins are on the same plane. The fact that the bent heat sink and the bent pins are on the same plane allows the traditional through-hole package to be converted into an advanced top heat sink package suitable for surface mounting. This design achieves an upgrade in package form without the need to develop a completely new lead frame system, which greatly saves development and mold costs.

[0008] Preferably, the minimum vertical distance between the left and right sides of the extended stress relief hole and the left and right sides of the heat sink is 1-1.5mm. Existing heat sinks have a circular hole. During the rib forming process, the heat sink often needs to be bent, typically along a horizontal line slightly below the horizontal center line of the circular hole. We define this horizontal line as the horizontal bending line. Because the bending width (the vertical distance from the intersection of the horizontal bending line and the side length of the circular hole to the side of the heat sink) is relatively large (3.36mm), the mechanical stress during bending is too high, easily leading to product delamination failure. Since the bending width of this invention (the minimum vertical distance between the left and right sides of the extended stress relief hole and the left and right sides of the heat sink) is only 1-1.5mm, less than the 3.36mm bending width in the prior art, it reduces the mechanical stress on the heat sink during bending, greatly reducing the risk of delamination of the encapsulated body, and significantly improving product yield and long-term reliability.

[0009] Preferably, the maximum horizontal distance of the extended stress relief hole is 1.8-2.2 times the maximum horizontal distance of the base hole; the maximum horizontal distance of the base hole is 3.5mm-3.8mm; and the maximum horizontal distance of the extended stress relief hole is 7-8mm.

[0010] Compared with the prior art, this utility model has the following advantages and beneficial effects: 1. Significantly reduces mechanical stress and fundamentally improves product reliability: The core innovation of this utility model lies in the design of a specific stress relief hole structure in the heat sink (composed of a rectangle or double-ended rounded rectangle connected to an upper semi-circular hole); this structure significantly reduces the effective bending width of the bending line from 3.36mm in the prior art to 1-1.5mm; this design fundamentally eliminates the huge mechanical stress generated during the bending process; this greatly avoids fatal failure problems such as delamination between the encapsulation and the heat sink caused by stress concentration, thereby significantly improving the product yield and long-term reliability.

[0011] 2. Strong compatibility, perfectly realizing package form conversion: This utility model is based on the mature TO-220 leadframe and is improved. Through a simple bending and forming process, the traditional through-hole package can be converted into an advanced top heat dissipation package suitable for surface mounting (such as a form similar to TO-263). This design realizes the upgrade of the package form without the need to develop a completely new leadframe system, which greatly saves development and mold costs.

[0012] 3. Optimize heat dissipation paths and improve device power density: Device heat dissipation is directly transferred from the top to the heat sink, reducing the heat dissipation path and thus reducing system thermal resistance; reducing heat transfer to the PCB increases PCB lifespan and reduces the impact on other devices, while also reducing PCB design complexity and cost; PCB utilization is improved, allowing other control devices to be mounted on the back of the PCB, further increasing PCB utilization and reducing cost, while shortening the distance between control devices and power devices reduces wiring length and parasitic parameters, thus improving system performance. Attached Figure Description

[0013] The accompanying drawings, which are included to provide a further understanding of the embodiments of the present invention and form part of this application, do not constitute a limitation thereof. In the drawings: Figure 1 It uses the existing TO-220 package structure.

[0014] Figure 2 This is a front view of the package structure with rectangular stress relief holes before the heat sink 1 and pin 3 are bent in this embodiment.

[0015] Figure 3 The images show the front view, left view, and back view of the package structure with rectangular stress relief holes after the heat sink 1 and pin 3 are bent in this embodiment.

[0016] Figure 4 This is a front view of the package structure with double-ended rounded rectangular stress relief holes before the heat sink 1 and pin 3 are bent in this embodiment.

[0017] Figure 5The images show the front view, left view, and back view of the package structure with double-ended rounded rectangular stress relief holes after the heat sink 1 and pin 3 are bent in this embodiment.

[0018] The attached diagram shows the markings and corresponding component names: 1. Heat sink; 2. Molded enclosure; 3. Pins; 4. Round hole; 5. Stress relief hole; 51. Rectangular stress relief hole; 52. Semi-circular stress relief hole; 53. Double-ended rounded rectangular stress relief hole. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of this utility model are only used to explain this utility model and are not intended to limit this utility model.

[0020] like Figure 1 As shown, Figure 1 It is an existing TO-220 package structure, which includes, from top to bottom, a heat sink 1, a molding compound 2, and leads 3; wherein, the heat sink is rectangular and has a circular hole 4; in the existing lead forming process, the heat sink often needs to be bent, generally along the horizontal center line of the circular hole 4, near the bottom (e.g., Figure 1 (As shown by the dotted line) The bending process is quite large, with a bending width of 3.36mm. This results in excessive mechanical stress during bending, which can easily lead to product delamination and failure.

[0021] like Figure 2 As shown, Figure 2 This is a front view of the package structure with rectangular stress relief holes before the heat sink 1 and pin 3 are bent in this embodiment. It includes a heat sink 1 and a molding compound 2, with the molding compound 2 located at the bottom of the heat sink 1. The heat sink 1 is rectangular, and stress relief holes 5 are provided on it. Each stress relief hole 5 includes a base hole and an extended stress relief hole. The extended stress relief hole is located at the bottom of the base hole and communicates with it. The base hole is a semi-circular stress relief hole 52, and the extended stress relief hole is a rectangular stress relief hole 51. At this time, the heat sink 1 is bent along the horizontal centerline of the rectangular stress relief hole 51 (e.g., ...). Figure 2 As shown by the dashed line, because the bending width (the perpendicular distance from the short side of the rectangular stress relief hole to the short side of the heat sink) is only 1.5mm, which is less than the 3.36mm in the prior art, the mechanical stress on the heat sink can be reduced during bending, greatly reducing the risk of delamination of the molding compound and significantly improving product yield and long-term reliability. Preferably, the long side length of the rectangular stress relief hole 51 is 7mm, and the diameter of the semi-circular stress relief hole 52 is 3.5mm.

[0022] like Figure 4 As shown, Figure 4 This is a front view of the package structure with double-ended rounded rectangular stress relief holes before the heat sink 1 and pin 3 are bent in this embodiment. It includes a heat sink 1 and a molding compound 2, with the molding compound 2 located at the bottom of the heat sink 1. The heat sink 1 is rectangular, and stress relief holes 5 are provided on it. Each stress relief hole 5 includes a base hole and an extended stress relief hole. The extended stress relief hole is located at the bottom of the base hole and communicates with it. The base hole is a semi-circular stress relief hole 52, and the extended stress relief hole is a double-ended rounded rectangular stress relief hole 53. At this time, the heat sink 1 is bent along the horizontal centerline of the double-ended rounded rectangular stress relief hole 53 (e.g., ...). Figure 4 As shown by the dashed line, since the bending width (the vertical distance from the vertex of the arc edge of the double-ended rounded rectangular stress relief hole 53 to the short side of the heat sink) is only 1mm, which is less than the 3.36mm in the prior art, the mechanical stress of the heat sink can be reduced during bending, which greatly reduces the risk of delamination of the plastic encapsulation and significantly improves the product yield and long-term reliability.

[0023] like Figure 3 As shown, Figure 3 These are the front view, left view, and back view of the package structure with rectangular stress relief holes 51 after the heat sink 1 and pin 3 are bent in this embodiment. Figure 5 As shown, Figure 5 These are the front view, left view, and back view of the package structure with double-ended rounded rectangular stress relief holes 53 after the heat sink 1 and pin 3 are bent in this embodiment. The heat sink 1 is bent along the horizontal center line of the extended stress relief hole, and the bent heat sink 1 and the bent pin 3 are on the same plane. This involves modifying the conventional TO-220 package during the lead-cutting process to create a TO-263 top heat sink package, meeting the heat dissipation requirements of high-power products. Device heat dissipation is directly transferred from the top to the heat sink, reducing the heat dissipation path and thus lowering system thermal resistance. It also reduces heat transfer to the PCB, increasing PCB lifespan and minimizing impact on other components. Furthermore, it reduces PCB design complexity and cost. Increased PCB utilization allows for the mounting of other control components on the back of the PCB, further improving PCB utilization and reducing costs. Simultaneously, the shorter distance between control components and power components reduces wiring length and parasitic parameters, improving system performance.

[0024] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this utility model. It should be understood that the above description is only a specific embodiment of this utility model and is not intended to limit the scope of protection of this utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the scope of protection of this utility model.

Claims

1. A top heat dissipation packaging structure based on a TO-220 frame, characterized in that, The device includes a heat sink (1) and a molding compound (2), with the molding compound (2) located at the bottom of the heat sink (1). The heat sink (1) is rectangular, and stress relief holes (5) are provided on the heat sink (1). The stress relief holes (5) include a base hole and an extended stress relief hole. The extended stress relief hole is located at the bottom of the base hole and is connected to the base hole. The maximum horizontal distance between the extended stress relief hole and the base hole is greater than the maximum horizontal distance between the base hole. The heat sink (1) is bent along the horizontal direction inside the extended stress relief hole.

2. The top heat dissipation packaging structure based on a TO-220 frame according to claim 1, characterized in that, The basic hole is a semi-circular stress relief hole (52).

3. The top heat dissipation packaging structure based on a TO-220 frame according to claim 1, characterized in that, The extended stress relief hole is a rectangular stress relief hole (51) or a double-ended rounded rectangular stress relief hole (53).

4. The top heat dissipation packaging structure based on a TO-220 frame according to claim 1, characterized in that, The heat sink (1) is bent along the horizontal center line of the extended stress relief hole, and the bent heat sink (1) and the bent pin (3) are on the same plane.

5. The top heat dissipation packaging structure based on a TO-220 frame according to claim 1, characterized in that, The minimum vertical distance between the left and right sides of the extended stress relief hole and the left and right sides of the heat sink (1) is 1-1.5mm.

6. The top heat dissipation packaging structure based on a TO-220 frame according to claim 1, characterized in that, The maximum horizontal distance of the extended stress relief hole is 1.8-2.2 times the maximum horizontal distance of the base hole.

7. The top heat dissipation packaging structure based on a TO-220 frame according to claim 1, characterized in that, The maximum horizontal distance between the foundation holes is 3.5mm-3.8mm.

8. A top heat dissipation packaging structure based on a TO-220 frame according to claim 1, characterized in that, The maximum horizontal distance between the extended stress relief holes is 7-8 mm.

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