Pinless top heat dissipation product frame design structure

Abstract

The utility model belongs to semiconductor top high heat dissipation chip packaging technical field discloses a kind of pinless top heat dissipation product frame design structure, through the frame pin front half-etching structure is set and cooperate back face shallow etching design, pin heat dissipation efficiency and mechanical strength are significantly improved;Frame base island back half-etching U type glue tank of preventing overflow effectively prevents plastic encapsulation material overflow, front plum blossom Dimple substantially increases heat dissipation area and strengthens plastic encapsulation material binding force, base island edge locking step further enhances interface reliability;Silver plating layer in welding area optimizes current transmission and bonding performance.The above structure synergistic effect realizes efficient heat dissipation path optimization in limited space, completely solves the problems, such as traditional packaging heat dissipation capacity deficiency, interface delamination and overflow risk, especially suitable for the stable operation of high power density semiconductor device.

Description

Technical Field

[0001] This utility model belongs to the field of semiconductor top heat dissipation chip packaging technology, specifically a leadless top heat dissipation product frame design structure. Background Technology

[0002] In the semiconductor field, power semiconductor devices are crucial for power and energy distribution and management. Improvements in the performance of power semiconductor devices themselves are the driving force behind the improvement of power system performance in terms of power density, power efficiency, operating frequency, reliability, and other aspects. With the miniaturization and high functionality of electronic devices, semiconductor processes are also constantly evolving towards higher integration and higher density. Various lightweight, thin, short, and small packaging structures have been developed, while the requirements for semiconductor devices are becoming increasingly stringent.

[0003] Currently, in semiconductor packaging products with high heat dissipation requirements, conventional heat dissipation structures mainly adopt bottom cooling, which conducts the heat generated by the chip away through the copper foil of the PCB board. This heat dissipation method has problems such as limited heat dissipation efficiency, larger PCB board size, and greater difficulty in heat dissipation. At the same time, existing leadframe structures often improve heat dissipation performance by increasing the area of ​​the base island, but because the base island is encapsulated by the product's molding compound, the area of ​​the base island is limited by the product's molding compound and cannot be further increased.

[0004] For products with high reliability and heat dissipation requirements, existing heat dissipation structures are no longer sufficient. Especially in high-power applications, the heat dissipation structures of conventional QFN products often fail to effectively dissipate heat, leading to increased chip temperature and impacting product stability and lifespan. Therefore, a new type of high-heat-dissipation packaging structure is urgently needed to solve these problems.

[0005] Regarding the issue of addressing the market demand for high-heat-dissipation products, several utility model patents have already been issued. For example: CN118412336A discloses a leadless, high-voltage, high-heat-dissipation product frame design structure and its packaging method. This patent utilizes a heat sink positioned on the front of the product, allowing heat from the chip to be dissipated from the front, thus enabling rapid heat transfer and stable product performance at the application end, meeting customer usage standards. However, the heat sink design still has room for improvement in heat dissipation efficiency.

[0006] CN210379037U discloses a leadless package structure with extended base islands on both sides for heat dissipation, featuring a high heat dissipation strip with pins. This patent fully utilizes the leadless sides of the product, extending the base islands outside the molded enclosure, significantly increasing the base island area; resulting in better heat dissipation performance, greater scalability, and wider applicability. However, the structure and size design of the base islands still require optimization to maximize their heat dissipation area and performance. Utility Model Content

[0007] This invention provides a leadless top heat dissipation product frame design structure, which solves the problem that conventional QFN product heat dissipation structures often cannot effectively dissipate heat, leading to increased chip temperature and affecting product stability and lifespan.

[0008] To achieve the above objectives, this utility model provides the following technical solution: A leadless top heat dissipation product frame design structure includes a frame body, with frame pins and frame base islands disposed at the bottom of the frame body. Both the frame pins and frame base islands are exposed on the bottom surface of the frame body. The front side of the frame pins is provided with a semi-etched structure, and the back side of the frame pins is provided with a semi-etched structure with a depth less than that of the front side. The back edge of the frame base island is provided with a semi-etched U-shaped anti-overflow adhesive groove, the front of the frame base island is provided with a plum blossom Dimple, the edge of the frame base island is provided with a locking step, and the welding areas of the frame pins and the frame base island are provided with a silver plating layer.

[0009] Preferably, the depth of the semi-etched U-shaped anti-overflow adhesive groove is 0.2-0.3 mm.

[0010] Preferably, the depth of the plum blossom dimple is 0.1-0.2 mm.

[0011] Preferably, the width of the locking step is 0.2-0.3 mm.

[0012] Preferably, the thickness of the silver plating layer in the soldering area of ​​the frame pins and the frame base island is 2.5-10 μm.

[0013] Preferably, the area of ​​the silver plating layer is 0.01 mm. 2 ~2mm 2 .

[0014] Preferably, the length of the frame pins is 2.0-4.0 mm.

[0015] Preferably, the depth of the semi-etched structure on the back side of the frame pin is 0.05~0.08μm.

[0016] Compared with existing technologies, this invention has the following advantages: This invention provides a leadless top-heat-dissipating product frame design structure. By setting a semi-etched structure on the front of the frame pins and combining it with a shallow etching design on the back, the heat dissipation efficiency and mechanical strength of the pins are significantly improved. The semi-etched U-shaped anti-overflow groove on the back of the frame base island effectively prevents molding compound overflow. The front-side dimple significantly increases the heat dissipation area and strengthens the bonding force of the molding compound. The locking step at the edge of the base island further enhances interface reliability. The silver plating layer in the soldering area optimizes current transmission and bonding performance. The synergistic effect of the above structures achieves efficient heat dissipation path optimization within a limited space, completely solving problems such as insufficient heat dissipation capacity, interface delamination, and overflow risk in traditional packaging. It is especially suitable for the stable operation of high-power-density semiconductor devices. Attached Figure Description

[0017] Figure 1 This is a design diagram of the frame pins for an embodiment of this utility model; Figure 2 This is a schematic diagram of the first bend in an embodiment of the present invention; Figure 3 This is a schematic diagram of the second bend in an embodiment of the present invention; Figure 4 This is a front view of the product before plastic sealing. Figure 5 This utility model Figure 2 Final product structure diagram of the embodiment; In the diagram, 1-Product pin; 2-Product pin front half-etch; 3-Product inner extension pin; 4-Base island back edge half-etch; 5-Base island back U-shaped half-etched groove; 6-Product inner extension pin silver plating; 7-Product power bar; 8-Product pin bending position; 9-Product base island connecting rib first bending position; 10-Product base island connecting rib second bending position; 11-Product base island front silver plating; 12-Base island front Dimple; 13-Pin front U-shaped groove design; 14-Product base island; 15-Chip; 16-Dip adhesive; 17-Molding material; 18-Bonding wire. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0019] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0020] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0021] 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.

[0022] like Figure 1 As shown, this utility model embodiment provides a design method for a leadless top heat dissipation product frame: 1. Frame Pin Design: A 15µm half-etch is designed on both sides of the front side of the frame pins, with an inward pin extension design. A half-etch is also designed on the back side of the inward pin extension. (Refer to...) Figure 1 ; 2. Frame Base Island Design: An anti-overflow step is designed on the back edge of the frame base island. For better secondary anti-overflow, a U-shaped groove design is added to the back. The front of the base island features a plum blossom-shaped dimple design, and anti-overflow adhesive grooves are designed along the edge of the base island; (Reference) Figure 1 ; 3. Frame fabrication: First, the shape is etched out using an etching method, and then silver is selectively electroplated onto the inner protrusion pins and base islands; 4. Frame recessing: First, create a V-groove on the pins 550µm inwards from the product edge. Then, bend the inner pins and base island for the first time, with a bending depth of A. (Refer to...) Figure 2 The third step is the second bend to the base island, with a bend depth of B, which forms the final frame. (Refer to...) Figure 3 ; 5. Using the above framework design for normal process packaging: thinning—dicing—core mounting—bonding—post-bonding film application—molding—polishing—tinning—printing—cutting.

[0023] 6. Finally, complete the product packaging. Figure 4 This is a picture of the product before it is sealed in plastic. Figure 5 This is the final product structure diagram.

[0024] Another embodiment of this utility model provides a leadless top-heat-dissipating product frame design structure, including a frame body, frame pins, and a frame base island. The frame body is used to house the chip, and the frame pins and frame base island are both located at the bottom of the frame body and exposed on the bottom surface of the frame body. The frame pins are 3.0mm long, with a 15μm half-etched structure on the front and a 10μm half-etched structure on the back. A 5μm thick silver plating layer is provided at the pin bonding wires to facilitate product bonding.

[0025] The base island is made of aluminum alloy, with a stepped edge 0.5mm high on the bottom surface to prevent moisture intrusion. The back edge of the base island features a semi-etched U-shaped anti-overflow groove with a depth of 0.25mm. The front edge of the base island features a 0.15mm deep plum blossom-shaped dimple. A 0.2mm wide locking step is located around the edge of the base island to increase adhesion with the molding compound. Both the front and back of the base island have a 5μm thick silver plating layer, and the unplated copper surface is roughened to ensure a tighter bond between the molding compound and the base island.

[0026] A design method for a leadless top heat dissipation product frame: During frame fabrication, a wet etching process is used to etch the frame shape, followed by selective silver plating of the leads and base islands. The frame is then bent twice at different locations using mechanical fixtures. The first bend is located 550μm inside the product edge, with a bending depth of 0.3mm. The second bend is located on the center line of the base islands, with a bending depth of 0.5mm, forming the final frame structure.

[0027] The product packaging process is as follows: chip thinning to 0.3mm, dicing, die mounting, bonding, post-bonding film application, encapsulation, polishing, tinning, printing, and cutting. These processes complete the product packaging.

[0028] Another embodiment of this utility model provides a leadless top-heat-dissipating product frame design structure, including a frame body, frame pins, and a frame base island. The frame body is used to house the chip, and the frame pins and frame base island are both located at the bottom of the frame body and exposed on the bottom surface of the frame body. The frame pins are 3.5mm long, with a 20μm half-etched structure on the front side and a 15μm half-etched structure on the back side. An 8μm thick silver plating layer is provided at the pin bonding wires to facilitate product bonding.

[0029] The base island is made of copper alloy, with a stepped edge 0.08mm high on the bottom surface to prevent moisture intrusion. The back edge of the base island features a semi-etched U-shaped anti-overflow groove 0.1mm wide and 0.035mm deep. The front edge of the base island features a 0.08mm deep plum blossom-shaped dimple. A 0.3mm wide locking step is located around the edge of the base island to increase adhesion with the molding compound. Both the front and back of the base island have an 8μm thick silver plating layer, and the unplated copper surface is roughened to ensure a tighter bond between the molding compound and the base island.

[0030] A design method for a leadless top heat dissipation product frame: During frame fabrication, a wet etching process is used to etch the frame shape, followed by selective silver plating of the leads and base islands. The frame is then bent twice at different locations using mechanical fixtures. The first bend is located 550μm inside the product edge, with a bending depth of 0.40mm. The second bend is located on the four connecting ribs of the base islands, with a bending depth of 0.6mm, forming the final frame structure.

[0031] The product packaging process is as follows: chip thinning to 0.4mm, dicing, die mounting, bonding, post-bonding film application, encapsulation, polishing, tinning, printing, and cutting. These processes complete the product packaging.

[0032] Although the embodiments of this utility model have been described above in conjunction with the accompanying drawings, this utility model is not limited to the specific embodiments and application fields described above. The specific embodiments described above are merely illustrative and instructive, and not restrictive. Those skilled in the art, guided by the description, can make many other forms without departing from the scope of protection of the claims of this utility model, and all of these are within the scope of protection of this utility model.

Claims

1. A leadless top heat dissipation product frame design structure, characterized in that, The frame includes a frame body, and the bottom of the frame body is provided with frame pins and frame base islands. Both the frame pins and frame base islands are exposed on the bottom surface of the frame body. The front side of the frame pins is provided with a semi-etched structure, and the back side of the frame pins is provided with a semi-etched structure with a depth less than that of the front side. The back edge of the frame base island is provided with a semi-etched U-shaped anti-overflow adhesive groove, the front of the frame base island is provided with a plum blossom Dimple, the edge of the frame base island is provided with a locking step, and the welding areas of the frame pins and the frame base island are provided with a silver plating layer.

2. The leadless top heat dissipation product frame design structure according to claim 1, characterized in that, The depth of the semi-etched U-shaped anti-overflow adhesive groove is 0.2-0.3mm.

3. The leadless top heat dissipation product frame design structure according to claim 1, characterized in that, The depth of the plum blossom dimple is 0.1-0.2 mm.

4. The leadless top heat dissipation product frame design structure according to claim 1, characterized in that, The width of the locking step is 0.2-0.3 mm.

5. The leadless top heat dissipation product frame design structure according to claim 1, characterized in that, The thickness of the silver plating layer in the soldering area of ​​the frame pins and frame base island is 2.5-10μm.

6. The leadless top heat dissipation product frame design structure according to claim 5, characterized in that, The area of ​​the silver plating layer is 0.01 mm. 2 ~2mm 2 .

7. The leadless top heat dissipation product frame design structure according to claim 1, characterized in that, The length of the frame pins is 2.0-4.0 mm.

8. The leadless top heat dissipation product frame design structure according to claim 1, characterized in that, The depth of the semi-etched structure on the back of the frame pins is 0.05~0.08μm.

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