Lead frame compatible with three packages

Abstract

This utility model relates to the field of semiconductor packaging technology, specifically to a lead frame compatible with three types of packages. It includes a heat sink and a core carrier plate, with the core carrier plate located at the bottom of the heat sink. Stress relief holes are provided on the heat sink, including basic holes and extended stress relief holes. The extended stress relief holes are located at the bottom of the basic holes and are connected to each other. The maximum vertical distance between the extended stress relief holes is 2.29mm-3.15mm. The heat sink is bent along a horizontal line formed by the intersection of the basic holes and the extended stress relief holes. This utility model, through a double-layer hole structure of "basic hole + extended stress relief hole" and using the intersection of the basic holes and the extended stress relief holes as the bending reference line, can simultaneously adapt to TO-262 packages, conventional TO-263 packages, and top-heat-dissipating TO-263 packages without changing the frame mold, reducing equipment investment and production changeover costs.

Description

Technical Field

[0001] This utility model relates to the field of semiconductor packaging technology, specifically to a lead frame that is compatible with TO-262 packages, conventional TO-263 packages, and top-heat-dissipating TO-263 packages. Background Technology

[0002] In semiconductor packaging manufacturing, the lead frame is a core component for chip fixation, signal conduction, and heat dissipation. Different package types (such as TO-262 and TO-263) have different requirements for the structural dimensions of the lead frame and the shape of the heat sink. In the current technology, a single lead frame can usually only be adapted to 1-2 package types. If multiple packages need to be produced, different lead frame molds need to be changed, resulting in high equipment investment and low production efficiency. Especially for the top-heat-dissipating TO-263 package, the existing lead frame has significant defects: on the one hand, when directly bent into shape, the heat sink cannot be kept on the same plane as the back of the device, which destroys the top heat dissipation path and causes the heat dissipation efficiency to drop by more than 50%, which cannot meet the requirements of high-power devices; on the other hand, if forced bending is used to meet the height requirements, huge mechanical stress will be generated at the connection between the heat sink and the frame, which will increase the cracking rate of the product to more than 30% during thermal cycling tests, seriously affecting reliability. Some solutions optimize stress and molding accuracy by adding a "slotting" process to the heat sink during production. However, this method requires additional slotting equipment (an investment of approximately 100,000-150,000 RMB per unit) and dedicated personnel for operation. It also extends batch processing time by 20%-30%, increases overall production costs by 15%-20%, and the extra process can easily introduce processing errors, further reducing product consistency. Therefore, there is an urgent need to design a leadframe that is compatible with multiple package types and balances reliability and economy. Utility Model Content

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a lead frame compatible with multiple package types. By optimizing the heat sink structure, it enables the use of TO-262 packages, conventional TO-263 packages, and top-heat-dissipated TO-263 packages, while solving the stress risks of forced bending and the cost of additional processes. To achieve the above objectives, the present invention adopts the following technical solution: A lead frame compatible with three types of packages includes a heat sink and a core carrier plate, the core carrier plate being located at the bottom of the heat sink; stress relief holes are provided on the heat sink, the stress relief holes including 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 vertical distance between the extended stress relief holes being 2.29mm-3.15mm, and the heat sink being bent along a horizontal line formed by the intersection of the base hole and the extended stress relief hole.

[0004] Preferably, the base hole is a semi-circular stress relief hole; the extended stress relief hole is a rectangular stress relief hole or a double-ended rounded rectangle stress relief hole; the double-ended rounded rectangle completely eliminates all sharp corners in the hole structure, which makes there no risk of stress concentration at any point of the entire extended stress relief hole, thus raising the reliability to the highest level.

[0005] Preferably, the package also includes leads extending from the carrier board. The heat sink is bent along a horizontal line formed by the intersection of the base hole and the extended stress relief hole, with the bent heat sink and the bent leads on the same plane. This coplanarity of the bent heat sink and leads allows for the conversion of traditional through-hole packages into advanced, surface-mount-compatible top-mount heat sink packages. This design achieves a package upgrade without requiring the development of a completely new leadframe system, significantly reducing development and mold costs.

[0006] 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. Because the bending width of this invention is only 1-1.5mm, it reduces the mechanical stress on the heat sink during bending, greatly reducing the risk of delamination of the molding compound, and significantly improving product yield and long-term reliability.

[0007] 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.

[0008] Compared with the prior art, this utility model has the following advantages and beneficial effects: 1. Multi-package compatibility: This utility model uses a double-layer hole structure of "basic hole + extended stress relief hole" and the heat sink is bent with the boundary line of the basic hole and the extended stress relief hole as the reference line. It can be adapted to TO-262 package (through hole), conventional TO-263 package (surface mount) and top heat sink type TO-263 package without changing the frame mold, reducing equipment investment and production switching costs. 2. Economic optimization: No new "heat sink slotting" process is required, the production time per batch is reduced by 20%-30%, the annual production capacity is increased by about 18%, and the raw material consumption per frame is reduced by 8%-12% by optimizing the heat sink material layout.

[0009] 3. This utility model uses a double-layer hole structure of "basic hole + extended stress relief hole" and the heat sink uses the intersection line of the basic hole and the extended stress relief hole as the bending reference line. This not only reduces bending stress, but also ensures that the heat sink and the back of the device are on the same plane after bending. Attached Figure Description

[0010] 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 This is a diagram of a lead frame that bends along the horizontal center line of a rectangular hole, as described in the prior art.

[0011] Figure 2 This is a diagram of a lead frame that bends along the horizontal center line of a circular arc hole, as described in the prior art.

[0012] Figure 3 This is a diagram of the lead frame with rectangular stress relief holes according to this utility model.

[0013] Figure 4 This is a diagram of the lead frame with double-ended rounded rectangular stress relief holes according to this utility model.

[0014] The attached diagram shows the markings and corresponding component names: 1. Heat sink; 2. Core board; 3. Pins; 4. Composite hole; 41. Arc hole; 42. Rectangular hole; 5. Stress relief hole; 51. Semi-circular hole; 52. Rectangular stress relief hole; 53. Double-ended rounded rectangular stress relief hole. Detailed Implementation

[0015] 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. Example

[0016] like Figure 1-2 As shown, Figure 1-2This is a diagram of a lead frame that bends along the horizontal center line of a rectangular hole or along the horizontal center line of an arc hole, as used in existing technology. It can be used for TO-262 and TO-263 packages. It includes a heat sink 1, a core board 2, and leads 3. The core board 2 is located below the heat sink 1, and the leads 3 are also located below the core board 2. The heat sink 1 has a composite hole 4, which includes an arc hole 41 and a rectangular hole 42. The arc hole 41 is a large arc, and the rectangular hole 42 is located below the arc hole 41 and is connected to the arc hole 41. The long side of the rectangular hole 42 is 8.84 mm, and the short side is 0.98 mm. For top-heat-dissipated TO-263 packages, it is often necessary to bend along the horizontal center line of either the rectangular hole or the arc hole. Figure 1 or Figure 2 If bending is performed along the horizontal line of the center of the rectangular hole (in the direction of the dotted line), Figure 1 Bending along the direction of the dotted line (in the direction of the bend) results in relatively low bending stress, but after bending, the heat sink 1 cannot be on the same plane as the back of the device; if along the horizontal line of the center of the arc hole (in the direction of the bend), the heat sink 1 cannot be on the same plane as the back of the device; Figure 2 (Direction of the dotted line) Bending, although the heat sink 1 can be on the same plane as the back of the device after bending, the large bending width results in significant mechanical stress, which will affect the reliability of the product.

[0017] Based on the above-mentioned technical problems, this application makes the following improvements to the composite hole 4 of the heat sink 1, such as... Figure 3-4 As shown, the device includes a heat sink 1 and a core plate 2. The core plate 2 is located at the bottom of the heat sink 1. 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 vertical distance between the extended stress relief holes is 2.29mm-3.15mm. The heat sink 1 is bent along the horizontal line formed by the intersection of the base hole and the extended stress relief hole.

[0018] Preferably, the basic hole is a semi-circular hole 51.

[0019] Preferably, the extended stress relief hole is a rectangular stress relief hole 52 (see...). Figure 3 ) or double-headed rounded rectangular stress relief hole 53 (see Figure 4 ).

[0020] Preferably, it also includes pins 3 extending from the core plate 2, wherein the heat sink 1 is bent along the horizontal line formed by the intersection of the base hole and the extended stress relief hole, and the bent heat sink 1 and the bent pins 3 are on the same plane.

[0021] 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 1 is 1-1.5mm.

[0022] 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.

[0023] Preferably, the maximum horizontal distance between the basic holes is 3.5mm-3.8mm.

[0024] Preferably, the maximum horizontal distance of the extended stress relief holes is 7-8 mm.

[0025] This invention utilizes a double-layer hole structure consisting of a "basic hole + extended stress relief hole" and uses the intersection of the basic hole and the extended stress relief hole as the bending reference line for the heat sink. It can simultaneously adapt to TO-262 packages (through-hole), conventional TO-263 packages (surface mount), and top-heat-dissipating TO-263 packages without the need to change the frame mold, thus reducing equipment investment and production switching costs.

[0026] 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 lead frame compatible with three types of packages, characterized in that: The device includes a heat sink (1) and a core plate (2), with the core plate located at the bottom of the heat sink. Stress relief holes (5) are provided on the heat sink. The stress relief holes 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 vertical distance between the extended stress relief holes is 2.29mm-3.15mm. The heat sink is bent along the horizontal line formed by the intersection of the base hole and the extended stress relief hole.

2. The lead frame compatible with three types of packages according to claim 1, characterized in that, The basic hole is a semi-circular hole (51).

3. A lead frame compatible with three types of packages according to claim 1, characterized in that, The extended stress relief hole is a rectangular stress relief hole (52) or a double-ended rounded rectangular stress relief hole (53).

4. A lead frame compatible with three types of packages according to claim 1, characterized in that, It also includes pins (3) extending from the core plate. When the heat sink is bent along the horizontal line formed by the junction of the base hole and the extended stress relief hole, the bent heat sink and the bent pin are on the same plane.

5. A lead frame compatible with three types of packages 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 is 1-1.5mm.

6. A lead frame compatible with three types of packages 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. A lead frame compatible with three types of packages according to claim 1, characterized in that, The maximum horizontal distance between the foundation holes is 3.5mm-3.8mm.

8. A lead frame compatible with three types of packages according to claim 1, characterized in that, The maximum horizontal distance between the extended stress relief holes is 7-8 mm.

Images