TO-220 packaging structure

Abstract

The invention discloses a TO-220 packaging structure. The TO-220 packaging structure comprises a base; a chip is installed on the end face of the base, pins are fixed to one end of the base and connected with the chip through a bonding wire A and a bonding wire B, the other end of the base is connected with a cooling fin, the number of the pins is three, one ends of the three pins are installed on the edge of the base in parallel, and the other ends of the three pins are installed on the other end of the base in parallel. The outer side of the base is wrapped by a plastic package cover, the stress borne by the pins in the using process is dispersed by punching the pins of the frame, the stability of the pins in plastic package materials is enhanced, the product failure probability caused by the pin problems is reduced, the adhesiveness of the plastic package materials and the base is better by avoiding roughening treatment, and the service life of the plastic package materials is prolonged. Therefore, the product can exactly resist the influence of the external environment.

Description

Technical Field

[0001] This invention relates to a TO-220 package structure. Background Technology

[0002] In the semiconductor packaging field, TO-220 packaging is a common packaging form, widely used in various power devices. However, current TO-220 packaged products often face problems such as delamination between the molding compound and the frame, and insufficient pin stability during practical use, which seriously affects the reliability and lifespan of the products. Delamination between the molding compound and the frame allows moisture intrusion, leading to problems such as degraded electrical performance and corrosion, ultimately causing device failure. Furthermore, the frame pins also need to possess sufficient stability during use to ensure the reliability of the electrical connection. Traditional TO-220 packaging processes have certain limitations in solving these problems and cannot meet the growing demand for high-reliability semiconductor devices. Therefore, there is an urgent need for a new method to improve the reliability of TO-220 packaged products and solve the problems of molding compound and frame delamination and insufficient frame pin stability. Summary of the Invention

[0003] The technical solution of this invention: A TO-220 package structure includes a base; a chip is mounted on the end face of the base, one end of the base is fixed with pins, the pins are connected to the chip through bonding wires A and B, the other end of the base is connected to a heat sink, the pins are three in number, one end of the three pins is mounted parallel to the edge of the base, and the outer side of the base is wrapped with a plastic cover.

[0004] The base has a wafer carrier stage in the middle, and a chip bonding part is located at the center of the wafer carrier stage. The base has bosses on both sides, and the cross-section of the bosses is trapezoidal.

[0005] Except for the chip soldering area, the surface of the base is machined into a rough surface.

[0006] The chip is connected to the pins on both sides of the three pins via bonding wires A and B, respectively, and the remaining pin is connected to the surface of the base.

[0007] The pins on both sides are fixed to the base by side connectors, and the pin in the middle is fixed to the base by a center connector. The side connectors are right trapezoids, and the center connectors are isosceles bodies. The hypotenuses of the side connectors are opposite to the hypotenuses of the center connectors.

[0008] A bonding hole is also machined at the connection between the pin and the center contact, and the ends of the bonding wire A and the bonding wire B are fixed in the bonding hole.

[0009] A limiting step is also machined in the middle of the pin.

[0010] The pin is also provided with a reinforcing rib at its end, which is located on the center line of the pin.

[0011] The heat sink is also machined with mounting holes.

[0012] The ends of the pins are rounded.

[0013] The beneficial effects of this invention are: By drilling holes at the frame pins, the stress on the pins during use is dispersed, the stability of the pins in the molding compound is enhanced, the probability of product failure due to pin problems is reduced, and by avoiding roughening treatment, the adhesion between the molding compound and the base is better, so that the product can just resist the influence of the external environment. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the package structure.

[0015] Figure 2 This is a schematic diagram of the base structure.

[0016] Reference numerals: 1-Heat sink, 2-Plastic cover, 3-Base, 31-Boss, 32-Die stage, 33-Chip bonding section, 4-Pin, 41-Limiting step, 42-Bonding hole, 43-Side connector, 44-Center connector, 5-Reinforcing rib, 6-Bonding line A, 7-Bonding line B, 8-Chip, 9-Mounting hole, 10-Guide groove. Detailed Implementation

[0017] Example 1: The purpose of this invention is to provide a method for improving the reliability of TO-220 packaged products, aiming to solve the problems of easy delamination between the molding compound and the frame and insufficient stability of the frame pins in existing TO-220 packaged products, thereby improving the overall reliability and service life of the product.

[0018] Frame pin drilling: Drilling is performed on the frame pins of the TO-220 package. By drilling small holes at specific locations on the pins, pin stability is effectively improved. The drilling locations are chosen in areas where the pin experiences concentrated stress. The diameter of the drilled holes is generally controlled between 0.28 and 0.32 mm, and mechanical drilling is used. After drilling, when the pin is subjected to external force and thermal stress, the stress can be dispersed through the small holes; after molding, the molding compound fills the holes, increasing the contact area between the molding compound and the frame, while simultaneously locking the frame's position within the molding compound, preventing lateral displacement of the frame. This improves the stability of the pin in electrical connections and reduces electrical faults caused by pin problems. After drilling, the drilling quality is inspected using a microscope to check whether the position, diameter, and depth of the holes meet the requirements, ensuring there are no defects such as burrs or cracks. By drilling holes at the frame leads, the stress on the leads during use is dispersed, enhancing the stability of the leads within the molding compound, thereby improving the reliability of the electrical connections in TO-220 packaged products and reducing the probability of product failure due to lead issues. Frame surface roughening treatment: The frame surface is roughened to increase the adhesion between the frame and the molding compound. Roughening treatment can employ methods such as chemical etching, physical blasting, or electrochemical treatment. Chemical etching utilizes a specific chemical solution to react with the metal on the frame surface, removing some metal and creating a microscopically rough surface structure. For example, for copper frames, a mixed solution containing nitric acid and hydrochloric acid can be used for etching; the surface roughness can be precisely controlled by adjusting the etching time and solution concentration. Physical blasting uses high-speed jets of abrasive particles to impact the frame surface, creating a micro-uneven structure that increases surface area and roughness. The particle size of the abrasive used in blasting is generally between 0.2 and 0.4 mm, and the blasting pressure is controlled between 0.3 and 0.5 MPa. Electrochemical treatment involves applying a certain voltage to an electrolyte solution to cause anodic dissolution on the frame surface, resulting in a roughened surface. After roughening treatment, the surface roughness Ra of the frame reaches 1.0-3.0 μm. Compared with the untreated smooth surface, the contact area with the molding compound is significantly increased, thereby significantly improving the mechanical bonding force between the frame and the molding compound and effectively preventing delamination between the molding compound and the frame during subsequent use.

[0019] After the frame surface is roughened, the adhesion between the plastic sealant and the frame is significantly enhanced, effectively solving the problem of easy delamination between the plastic sealant and the frame. This allows the product to better resist the influence of external environmental factors, such as moisture and temperature changes, improving the product's moisture resistance and temperature resistance, extending its service life, and enhancing its reliability in various complex working environments.

[0020] Packaging steps: Assemble the frame and chip after the above treatment, and then perform a molding process. Select a suitable molding compound and perform molding under specific temperature and pressure conditions, such as a molding temperature of 175℃, a molding pressure of 15kg / cm²-35kg / cm², and a curing time of 120s-180s. After molding, perform a post-curing treatment to further improve the performance and stability of the molding compound. Reliability Testing: A series of reliability tests were conducted on the packaged TO-220 products, including temperature cycling tests (1000 cycles between -55℃ and 125℃), damp heat tests (1000 hours at 85℃ and 85% relative humidity), and electrical performance tests. These tests verified the effectiveness of the method of this invention in improving the reliability of TO-220 packaged products.

Claims

1. A TO-220 package structure comprising a base (3), characterized in that: The end face of the base (3) is provided with a chip (8), one end of the base (3) is fixed with a pin (4), the pin (4) is connected with the chip (8) through bonding wire A (6) and bonding wire B (7), the other end of the base (3) is connected with the heat sink (1), the pin (4) is three, one end of the three pins (4) is parallelly arranged on the edge of the base (3), and the outer side of the base (3) is wrapped by the plastic package cover (2).

2. The TO-220 package structure of claim 1, wherein: The middle part of the base (3) is provided with a slide glass table (32), the center of the slide glass table (32) is provided with a chip welding part (33), and the two sides of the base (3) are provided with bosses (31), and the cross section of the boss (31) is trapezoidal.

3. The TO-220 package structure of claim 1, wherein: The surface of the base (3) is roughened except the surface of the chip welding part (33).

4. The TO-220 package structure of claim 1, wherein: The chip (8) is connected with the pins (4) on the two sides through bonding wire A (6) and bonding wire B (7), and the remaining pin (4) is connected with the surface of the base (3).

5. The TO-220 package structure of claim 4, wherein: The pins (4) on the two sides are fixed on the base (3) through the side connecting pieces (43), the middle pin (4) is fixed on the base (3) through the middle connecting piece (44), the side connecting piece (43) is a right trapezoid, the middle connecting piece (44) is an isosceles body, and the oblique edges of the side connecting piece (43) are opposite to the oblique edges of the middle connecting piece (44).

6. The TO-220 package structure of claim 5, wherein: The pin (4) is further provided with a bonding hole (42) at the connecting position of the pin (4) and the middle connecting piece (44), and the ends of the bonding wire A (6) and the bonding wire B (7) are fixed in the bonding hole (42).

7. The TO-220 package structure of claim 1, wherein: The middle part of the pin (4) is further provided with a limiting step (41).

8. The TO-220 package structure of claim 1, wherein: The end of the pin (4) is further provided with a reinforcing rib (5), and the reinforcing rib (5) is arranged on the center line of the pin (4).

9. The TO-220 package structure of claim 1, wherein: The heat sink (1) is further provided with a mounting hole (9).

10. The TO-220 package structure of claim 1, wherein: The end of the pin (4) is further provided with a reinforcing rib (5), and the reinforcing rib (5) is arranged on the center line of the pin (4).

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