Packaging structure with cavity structure

Abstract

The utility model discloses a packaging structure with a cavity structure, which comprises a packaging frame, the packaging frame comprises a base island and pins arranged at the periphery of the base island, a chip is arranged on the base island, the chip is electrically connected with the pins, a cover cap with an integrated structure is covered on the frame, the cover cap is made of PBT (polybutylene terephthalate) or PPS (polyphenylene sulfide) plastic materials and is fixedly adhered with the packaging frame through an adhesive, and the packaging frame is provided with a cavity. The cover comprises four enclosures and a top cover, the four enclosures are located on the outer sides of the pins, a cavity is formed between the cover and the packaging frame, the chip, the pins and the bonding wires are contained in the cavity, plastic packaging layers are arranged on the periphery and the top face of the cover, and the bottoms of the plastic packaging layers are bonded with the packaging frame. According to the utility model, the cavity structure is prepared on the frame and is integrally encapsulated, so that more air circulation is allowed through the cavity structure, the heat dissipation capability of the product is improved, the stress generated by the thermal expansion problem of the chip and the plastic package body is improved, the stability and reliability of the device are improved, the weight of the product can be reduced, and the production cost is reduced. The product process is easy to realize and the cost is reduced.

Description

Technical Field

[0001] This utility model relates to the field of semiconductor packaging technology, and more specifically to a packaging structure with a cavity structure. Background Technology

[0002] Packaging, as a core component of the semiconductor industry and a downstream technology link in the entire IC supply chain, primarily serves several functions: protecting the chip, supporting the chip and its form factor, connecting the chip's electrodes to external circuits to enhance heat dissipation, standardizing specifications, and facilitating the connection of the chip's I / O ports to component-level and system-level PCBs, glass substrates, and other materials to achieve circuit connectivity and ensure normal circuit operation. Packaging shell materials mainly include plastic, ceramic, and metal. Plastic packaging has relatively poor heat dissipation and is typically used for simple circuit packaging. Ceramic packaging can achieve hermetic sealing structures and has excellent heat dissipation; however, because ceramic shells require sintering and molding, the cost is relatively high, so it is mostly used in high-reliability applications. Metal packaging offers the best heat dissipation, but because metal is conductive, it cannot be directly used as a packaging shell.

[0003] Although ceramic packaging has excellent heat dissipation and high reliability and mature applications, the rapid development of integrated circuits and the shrinking chip size have led to higher requirements for size, weight and cost in various applications, which has greatly limited the application of ceramic packaging.

[0004] First, ceramic encapsulation requires relatively high processing temperatures, necessitating sintering at even higher temperatures. This not only consumes more energy but also places higher demands on equipment, directly leading to a significant increase in production costs. This is particularly disadvantageous in large-scale production aimed at cost-effectiveness. Second, ceramic encapsulation is less capable of automation and miniaturization. Modern products are increasingly trending towards miniaturization and thinner designs, but the hardness and brittleness of ceramic materials make them more susceptible to damage during the thinning process, making it difficult to meet market demands. Furthermore, the widespread adoption of automated production lines requires encapsulation processes to be universally applicable, but the customized needs of ceramic encapsulation prevent it from meeting the requirements of large-scale production applications. Finally, ceramic materials are more easily damaged by external stress. This stress damage not only affects product reliability but also shortens product lifespan, a problem particularly pronounced in mobile devices and portable electronic products.

[0005] Because ceramic encapsulation suffers from drawbacks such as cost, automation limitations, and high brittleness and susceptibility to damage, the more adaptable plastic encapsulation is being considered as a replacement. Plastic encapsulation materials are less expensive, the manufacturing process is mature, and the degree of automation is high, significantly reducing production costs. Its encapsulation form more easily meets the current demands for thinner and lighter electronic products. Plastic encapsulation also has advantages in flexibility, deforming under external forces without easily breaking. This characteristic makes plastic encapsulation superior in applications involving complex shapes. It also exhibits excellent impact resistance, withstanding significant impacts and vibrations, thereby improving the reliability and durability of devices, making it suitable for applications in aerospace and military fields.

[0006] A common plastic encapsulation structure consists of a frame, a base island, a chip, metal leads, and pins. The pins are located around the perimeter of the package, which encapsulates the chip leads and the chip itself. The chip is mounted to the base island using adhesive, and the chip pads are electrically connected to the pins via wire bonding. In radio frequency (RF) devices and stress-sensitive packaging products, the plastic encapsulation has a higher coefficient of thermal expansion, significantly different from that of the chip and copper frame. Therefore, internal stress can develop within the encapsulation when heated, leading to fracture and failure. RF power devices, in particular, generate substantial heat during operation, and purely plastic encapsulation cannot dissipate this heat quickly and effectively, resulting in thermal failure and impacting device stability and reliability.

[0007] Therefore, it is necessary to study a plastic encapsulation structure that improves cost, space, stress and heat dissipation, so as to improve the reliability of the device to a certain extent and reduce the production cost. Utility Model Content

[0008] To address the aforementioned issues, this invention provides a packaging structure with a cavity structure. By fabricating a cavity structure on a frame and encapsulating it as a whole, the stress caused by thermal expansion issues between the chip and the molding compound is reduced, thereby increasing the product's heat dissipation capacity, improving the stability and reliability of the device, and significantly reducing the product cost compared to ceramic devices.

[0009] According to one aspect of the present invention, a packaging structure with a cavity structure is provided, comprising a packaging frame, the packaging frame including a base island and pins disposed around the base island, a chip disposed on the base island, the chip and the pins being electrically connected by bonding wires, a cover being provided on the frame, the cover including four side enclosures and a top cover, the four side enclosures being located outside the pins, a cavity being formed between the cover and the packaging frame, the chip, pins and bonding wires being housed in the cavity, a molding layer being provided around the cover and on the top surface, the bottom of the molding layer being bonded to the packaging frame.

[0010] In some embodiments, the cover consisting of the four sides of the enclosure and the top cover is an integral structure.

[0011] In some implementations, the cover is made of PBT or PPS plastic.

[0012] In some implementations, the cover is bonded to the encapsulation frame with an adhesive.

[0013] In some implementations, a cutting groove is formed between the molding layers of adjacent encapsulation structures.

[0014] Compared with existing technologies, the beneficial effects of this utility model are as follows: This utility model provides a packaging structure with a cavity structure. A plastic cover is placed on the frame, forming a cavity above the chip, pins, and bonding wires. The product is then encapsulated with molding compound. The molding layer wraps around the cover and is bonded to the frame. Compared with traditional encapsulation structures, the internal cavity structure of this packaging structure allows for more airflow, which helps with heat dissipation. When the chip is working, heat is dissipated quickly and promptly through the air, cover, and packaging frame, avoiding the packaging material's obstruction of heat conduction. This reduces problems such as blistering and cracking caused by high-temperature molding compound, and reduces performance degradation and reliability issues caused by high temperatures. This advantage is particularly important for high-frequency applications; and due to the cavity structure, weight can be reduced by decreasing the amount of molding compound used, thereby lowering production and transportation costs, making it especially suitable for scenarios requiring weight control. The cavity design also reduces internal stress during chip heating because the chip does not directly contact the encapsulant, preventing cracks and delamination caused by thermal expansion mismatch, further improving package reliability. Furthermore, the cavity structure reduces stray inductance, electromagnetic interference, and oscillations, improving product stability and performance, enabling operation at higher frequencies, and reducing oscillations caused by energy conversion between inductors and capacitors. In RF device applications, compared to traditional ceramic packaging structures, it offers more flexible processing methods, simpler manufacturing, easier implementation, and lower cost, resulting in lower overall production costs. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of one embodiment of the encapsulation structure with a cavity structure provided by this utility model;

[0016] Figure 2 This is a schematic diagram of a packaging structure with a cavity structure from another perspective;

[0017] Figure 3 This is a schematic diagram of the packaged structure before it is cut into individual products. Detailed Implementation

[0018] The present invention will be further described below with reference to specific embodiments.

[0019] like Figure 1 and 2As shown, an embodiment of the present invention provides a packaging structure with a cavity structure, including a packaging frame 1. The packaging frame 1 includes a base island 11 and pins 12 disposed around the base island 11. A chip 2 is mounted on the base island 11. The chip 2 and the pins 12 are electrically connected through bonding wires 3. A cover 4 is bonded to the frame. The cover 4 has four side enclosures 41 and a top cover 42. The four side enclosures 41 are located outside the pins 12. A cavity 100 is formed between the cover 4 and the packaging frame 1. The chip 2, pins 12, and bonding wires 3 are housed in the cavity 100. The cover 4 is encapsulated around its perimeter and top surface with a molding compound to form a molding layer 5. The bottom of the molding layer 5 is bonded to the packaging frame 1.

[0020] The cover 4 is made of PBT (polybutylene terephthalate) plastic or PPS (polyphenylene sulfide) plastic. The four sides 41 and the top cover 42 of the cover 4 are an integral structure formed by injection molding. The cover 4 is a pre-made spare part.

[0021] The cover 4 is bonded to the encapsulation frame 1 using epoxy resin adhesive.

[0022] like Figure 3 As shown, the product is a combination of several encapsulation units that are encapsulated as a whole and then cut into individual pieces. To facilitate cutting, when the encapsulation layer 5 is formed, a groove 51 is formed between the surfaces of the encapsulation layers 5 of adjacent encapsulation units to facilitate subsequent cutting.

[0023] The packaging method for the above-mentioned cavity-structured packaging structure is as follows:

[0024] Chip 2 or other components are mounted on the packaging frame 1; wire bonding is used to electrically connect chip 2 and pin 12 through bonding wire 3; the position to be bonded to cover 4 is designed on the frame, and a ring of epoxy resin is coated as an adhesive material; the plastic cover 4 is bonded to the epoxy resin with epoxy resin adhesive, and after standing at room temperature, the cover 4 is cured and tightly bonded to the frame; then the frame is completely encapsulated with molding compound, which fills the gaps between each cover 4 and covers the top surface of cover 4; grooves 51 are processed on the upper surface of the molding layer 5 according to the cutting lines of each packaging unit; the encapsulated frame is cut into individual products along the grooves 51.

[0025] This packaging structure features a cavity structure. The cover 4 forms a cavity 100 above the chip 2, pins 12, and bonding wires 3 before overall molding. Compared to traditional encapsulation structures, the internal cavity structure in this packaging structure allows for more airflow, which helps with heat dissipation. When the chip 2 is working, the heat is dissipated quickly and promptly through the air, cover 4, and packaging frame 1, avoiding the packaging material's obstruction of heat conduction and reducing problems such as blistering and cracking caused by high-temperature molding materials. This also reduces performance degradation and reliability issues caused by high temperatures, which is particularly important for high-frequency applications.

[0026] The cavity design prevents direct contact between the chip 2 and the encapsulating material during heat generation, reducing internal stress and preventing cracks and delamination caused by thermal expansion mismatch, thus further improving package reliability. The cavity structure also reduces stray inductance, electromagnetic interference, and oscillations, improving product stability and performance, enabling operation at higher frequencies, and minimizing oscillations caused by energy conversion between inductors and capacitors. In RF device applications, compared to traditional ceramic packaging structures, it offers more flexible manufacturing processes, simpler processing, easier implementation, and lower cost, resulting in lower overall production costs.

[0027] In addition, due to the presence of the cavity structure, the weight can be reduced by decreasing the amount of molding compound used, thereby reducing production and transportation costs, making it particularly suitable for scenarios requiring weight control.

[0028] The above descriptions are merely some embodiments of this utility model. It should be noted that those skilled in the art can make other modifications and improvements without departing from the inventive concept of this utility model, and these all fall within the protection scope of this utility model.

Claims

1. A packaging structure with a cavity structure, comprising a packaging frame (1), the packaging frame (1) comprising a base island (11), pins (12) arranged at the periphery of the base island (11), a chip (2) arranged on the base island (11), and the chip (2) being electrically connected to the pins (12) through bonding wires (3), characterized in that, The cover (4) is arranged on the packaging frame (1), the cover (4) comprises a four-side enclosure (41) and a top cover (42), the four-side enclosure (41) is located outside the pin (12), a cavity (100) is formed between the cover (4) and the packaging frame (1), the chip (2), the pin (12) and the bonding wire (3) are accommodated in the cavity (100), a plastic sealing layer (5) is arranged on the periphery and the top surface of the cover (4), and the bottom of the plastic sealing layer (5) is bonded to the packaging frame (1).

2. The package structure having a cavity structure according to claim 1, wherein, The cover (4) formed by the four-side enclosure (41) and the top cover (42) is an integral structure.

3. The package structure with cavity structure according to claim 2, wherein, The cover (4) is made of PBT plastic material or PPS plastic material.

4. The package structure with cavity structure according to claim 1 or 3, characterized in that, The cover (4) and the packaging frame (1) are fixed by adhesive bonding.

5. The package structure having a cavity structure according to claim 4, wherein, Cutting grooves (51) are formed between the plastic sealing layers (5) of adjacent packaging structures.

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