Chip underfill structure, system, and method

Abstract

The application provides a chip underfill structure, system and method. The chip underfill structure is used for injecting underfill adhesive to the bottom of a chip fixed on a substrate. The chip underfill structure comprises at least two pressurized filling ends, a negative pressure suction end and a flexible sealing member. The at least two pressurized filling ends are detachably arranged above the substrate and located around the chip. The negative pressure suction end is detachably arranged on the substrate and forms a surrounding cavity with the pressurized filling ends in a head-to-tail form and in a form that the pressurized filling ends and the negative pressure suction end are not communicated with each other. The flexible sealing member is arranged at least around the chip, between the negative pressure suction end and the chip and between the pressurized filling end and the chip, so as to form a closed space between the chip and the substrate. The problem of slow filling speed and easy generation of adhesive voids of the chip underfill structure is solved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor packaging technology, and more specifically, to a chip bottom filling structure, system, and method. Background Technology

[0002] Traditional underfill methods for semiconductor packaging, a key technology in the field, rely on a single injection port and natural capillary action to fill the substrate with a filler adhesive (usually epoxy resin). Using a single injection port, the filler adhesive needs to gradually diffuse through the tiny gaps between the chip and the substrate via natural capillary action. However, this natural diffusion process is slow, significantly extending the packaging production cycle.

[0003] Furthermore, natural capillary action can also lead to bubble formation during the filling process. When the filler diffuses in the gaps, if it encounters obstruction or uneven flow rate, cavities may form, which in turn trap air and form bubbles. These bubbles are like time bombs hidden inside the package, posing a constant threat to the overall quality and reliability of the package.

[0004] Uneven filling is a major challenge faced by traditional underfill methods in chip packaging. Because the gap between the chip and the substrate may not be perfectly uniform, and due to the limitation of a single injection port, the filler adhesive may exhibit concentration differences during diffusion, resulting in some areas being overfilled while others are underfilled. This uneven filling not only affects the appearance of the package but may also adversely impact its mechanical strength, thermal management performance, and electrical performance.

[0005] In summary, traditional underfill methods for chip packaging suffer from significant drawbacks, including slow filling speed, susceptibility to air bubbles, and uneven filling. These issues not only prolong the packaging production cycle and increase costs but also potentially weaken the overall quality and reliability of the package, posing a threat to the long-term stable operation of the chip. Therefore, the industry urgently needs to find more efficient and reliable underfill technologies to meet current chip packaging requirements. Summary of the Invention

[0006] In view of the problems existing in the prior art described above, this application provides a chip bottom filling structure, system, and method to solve the problems of slow filling speed and easy formation of voids in the adhesive material in chip bottom filling structures.

[0007] To achieve the above and other related objectives, the present invention provides a chip bottom filling structure for injecting filler adhesive into the bottom of a chip fixed on a substrate, comprising:

[0008] At least two pressurized filling ends are detachably disposed above the substrate and around the chip;

[0009] The negative pressure suction end is detachably mounted on the substrate and forms a cavity with the pressurized filling end connected end to end but not connected to each other.

[0010] Flexible seals are disposed at least around the chip, between the negative pressure suction end and the chip, and between the pressurized filling end and the chip, to form a sealed space between the chip and the substrate.

[0011] Optionally, the number of pressurized filling terminals is three, and the three pressurized filling terminals are respectively located on three sides of the chip, and the three pressurized filling terminals are not connected to each other.

[0012] Optionally, the bottom filling structure of the chip also includes:

[0013] The adhesive filling cavity is connected to the pressurized filling end to inject filling adhesive into the pressurized filling end.

[0014] Optionally, a flexible seal is also provided on the top of the chip.

[0015] Optionally, the flexible seal is made of silicone rubber, polytetrachloroethylene, or fluororubber.

[0016] Optionally, the pressurized filling end includes a filling channel, a first injection port, and a second injection port. The first injection port and the second injection port are formed on the filling channel. The first injection port is connected to the external environment, and the second injection port is connected to the sealed space.

[0017] Optionally, the negative pressure suction end includes a suction channel, a first suction port, and a second suction port. The first suction port and the second suction port are formed on the suction channel. The first suction port is connected to the external environment, and the second suction port is connected to a closed space.

[0018] Optionally, the first injection port is at least one circular hole.

[0019] Another aspect of the present invention provides a chip underfill system, comprising:

[0020] Chip bottom filling structure, including the chip bottom filling structure described above;

[0021] The positive pressure module is connected to the pressurized filling end of the bottom filling structure of the chip to form positive pressure in the sealed space between the chip and the substrate;

[0022] A flow control device, connected to the positive pressure module, controls the amount of filler adhesive injected into the sealed space;

[0023] The negative pressure module is connected to the negative pressure suction end of the filling structure at the bottom of the chip to form negative pressure in the sealed space between the chip and the substrate.

[0024] Another aspect of the present invention provides a chip underfilling method, which employs the chip underfilling structure described above. The chip underfilling method includes the following steps:

[0025] The bottom filling structure of the chip is placed on the substrate, so that a sealed space is formed between the chip and the substrate.

[0026] Positive pressure is applied to the sealed space through the pressurized filling end of the chip bottom filling structure to inject the filling adhesive into the sealed space;

[0027] Negative pressure is applied to the sealed space through the negative pressure suction end of the filling structure at the bottom of the chip to assist the filling adhesive in filling the sealed space and to remove excess filling adhesive.

[0028] As described above, the chip bottom filling structure, system, and method provided by the present invention have at least the following beneficial technical effects:

[0029] The chip bottom filling structure of the present invention is used to inject filler adhesive into the bottom of a chip fixed on a substrate, comprising at least two pressurized filling ends, a negative pressure suction end, and a flexible sealing member. At least two pressurized filling ends are detachably disposed above the substrate and around the chip. The negative pressure suction end is detachably disposed on the substrate and forms a cavity with the pressurized filling ends in a connected but non-communicating manner. The flexible sealing member is disposed at least around the chip, between the negative pressure suction end and the chip, and between the pressurized filling end and the chip, to form a sealed space between the chip and the substrate. This solves the problems of slow filling speed and easy formation of adhesive voids in chip bottom filling structures. Attached Figure Description

[0030] Figure 1 The image shown is a top view of the chip bottom filling structure provided in Embodiment 1 of the present invention.

[0031] Figure 2 Displayed as Figure 1 The diagram shows the cavity formed by the bottom filling structure of the chip.

[0032] Figure 3 The image shown is a cross-sectional view from angle AA of the chip bottom filling structure without filler adhesive provided in Embodiment 1 of the present invention.

[0033] Figure 4 The image shown is a cross-sectional view of the chip bottom filling structure from the perspective of AA in an optional embodiment provided in Embodiment 1 of the present invention.

[0034] Figure 5 The image shown is a cross-sectional view of the chip bottom filling structure from the perspective of AA, as provided in another optional embodiment of Embodiment 1 of the present invention.

[0035] Figure 6The image shown is a cross-sectional view from AA perspective of the chip bottom filling structure including the adhesive filling cavity provided in Embodiment 1 of the present invention.

[0036] Figure 7 This is a schematic diagram of the functional modules of the chip bottom filling system provided in Embodiment 2 of the present invention.

[0037] Figure 8 The diagram shown is a flowchart of the chip bottom filling method provided in Embodiment 3 of the present invention.

[0038] Figure Labels

[0039] 1. Substrate; 11. Pressurized filling end; 111. Filling channel; 1111. First injection port; 1112. Second injection port; 12. Negative pressure suction end; 121. Suction channel; 1211. First suction port; 1212. Second suction port; 13. Chip; 14. Flexible sealant; 15. Adhesive filling cavity; 16. Solder ball point; 17. Filler adhesive container; 171. Filler adhesive; 172. Piston; 173. Opening; 18. Enclosure cavity; 19. Sealed space. Detailed Implementation

[0040] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0041] It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Although the illustrations only show components related to the present invention and are not drawn according to the actual number, shape and size of the components, the shape, quantity, positional relationship and proportion of each component can be arbitrarily changed under the premise of realizing the technical solution of this invention, and the layout of the components may also be more complex.

[0042] Example 1

[0043] This embodiment provides a chip bottom filling structure for injecting filler adhesive into the bottom of a chip fixed on a substrate, as shown in the figure. Figures 1 to 6 The bottom filling structure of the chip includes at least two pressurized filling ends 11, a negative pressure suction end 12, and a flexible seal 14.

[0044] Reference Figure 3 and Figure 4Chip 13 is fixedly connected to substrate 1 via solder balls 16, forming a space between them. Due to the significant difference in thermal expansion coefficients between chip 13 and substrate 1, thermal stress difference will occur under temperature cycling, causing the solder balls 16 connecting chip 13 and substrate 1 to break. This increases the thermal resistance of the bottom filler structure and may even cause the entire bottom filler structure to fail. A direct and simple solution to this problem is to fill the space between chip 13 and substrate 1 with filler adhesive 171. This increases the connection area between chip 13 and substrate 1, improves their bonding strength, and protects the solder balls 16.

[0045] Reference Figure 1 and Figure 4 To facilitate disassembly and cleaning, at least two pressurized filling ends 11 are detachably disposed above the substrate 1 and around the chip 13. This multi-sided design of the pressurized filling ends 11 allows the bottom filling structure of the chip to inject the filler adhesive 171 from multiple directions, thereby improving the uniformity and efficiency of filling and avoiding voids in the adhesive material during the filling process. In this embodiment, the injection speed of the filler adhesive 171 can be controlled to further avoid voids in the bottom filling structure of the chip. To allow for different designs of the pressurized filling ends 11 according to different requirements, the thickness of the pressurized filling ends 11 is between 1 mm and 2 mm. Optionally, the second injection port 1112 inside the pressurized filling end 11 and the bottom filling structure of the chip is a circular hole with a diameter between 40 μm and 60 μm, and further, the diameter of the second injection port 1112 is between 45 μm and 55 μm. In this embodiment, the diameter of the second injection port 1112 is 50 μm. This size range is designed to ensure that the filler 171 can pass smoothly while preventing excessively large particles or impurities from entering the bottom filling structure of the chip. In this embodiment, there are three pressurized filling ends 11, which are respectively located on the three sides of the chip 13 and are not interconnected. This layout helps ensure that the filler 171 can be uniformly injected into the bottom filling structure of the chip from multiple directions, thereby reducing the formation of bubbles and voids. The fact that the three pressurized filling ends 11 are not interconnected means that each of the three pressurized filling ends 11 works independently without interfering with each other. This design helps to more accurately control the injection speed and pressure of the filler 171, thereby improving the controllability and stability of the filling process. In an optional embodiment of this embodiment, refer to... Figure 2The pressurized filling end 11 includes a filling channel 111, a first injection port 1111, and a second injection port 1112, which are formed on the filling channel 111. The first injection port 1111 communicates with the external environment, allowing the external environment to apply positive pressure to the space between the chip 13 and the substrate 1 of the chip bottom filling structure through the first injection port 1111, so as to inject the filler 171 into the space between the chip 13 and the substrate 1. The second injection port 1112 communicates with the first injection port 1111 and the space between the chip 13 and the substrate 1 of the chip bottom filling structure, so as to inject the filler 171 into the space between the chip 13 and the substrate 1 of the chip bottom filling structure through the first injection port 1111. The first injection port 1111 of the filling channel 111 is at least a circular hole. The design of the circular vent hole helps to reduce the resistance of the filler during the flow process and makes it easier to distribute evenly along the channel. In addition, the circular hole is also easier to clean because it is less likely to leave dirt or residue during the cleaning process. Filler 171 is typically epoxy resin. Epoxy resin has good insulation, adhesion and thermal stability, which can effectively improve the reliability and durability of chip packaging.

[0046] Reference Figure 1 , Figure 2 and Figure 4The negative pressure suction end 12 is also detachably mounted on the substrate 1 for easy disassembly and cleaning. The negative pressure suction end 12 uses negative pressure to suction excess filler adhesive 17 from the bottom filling structure of the chip. This design helps ensure the accuracy and cleanliness of the bottom filling structure while reducing waste and contamination. The negative pressure suction end 12 and the pressurized filling end 11 are connected end-to-end but not interconnected, forming a cavity 18. The cavity 18 ensures that the filler adhesive 171 will not overflow outside the cavity 18 during injection. The filler adhesive 171 can only be injected into the bottom filling structure of the chip through the pressurized filling end 11, while excess filler adhesive 171 is extracted through the negative pressure suction end 12. The negative pressure suction end 12 and the pressurized filling end 11 are completely separated in the flow path, allowing them to work independently or simultaneously, accelerating the filling speed of the filler adhesive 171 and ensuring the accuracy and controllability of the filling process. The negative pressure suction end 12 includes a suction channel 121, a first suction port 1211, and a second suction port 1212, which are formed on the suction channel 121. The first suction port 1211 is connected to the external environment, allowing the external environment to apply negative pressure to the space between the chip 13 and the substrate 1 in the chip bottom filling structure through the first suction port 1211, assisting the filling adhesive 171 in filling the space between the chip 13 and the substrate 1, and removing excess filling adhesive 171. The second suction port 1212 is connected to the first suction port 1211 and the space between the chip 13 and the substrate 1 in the chip bottom filling structure, so that the filling adhesive 171 can be filled into the space between the chip 13 and the substrate 1 in the chip bottom filling structure through the first suction port 1211. Optionally, a piston 172 is provided in the suction channel 121, which can move inside the suction channel 121. The piston 172 in the suction channel 121 helps to enhance the suction vacuum effect.

[0047] Reference Figures 1 to 5 Chip 13 is disposed within cavity 18 and connected to substrate 1 via solder balls 16. Chip 13 is spaced apart from pressurized filling end 11 and negative pressure suction end 12. Flexible sealing member 14 is disposed at least around chip 13, located between pressurized filling end 11 and negative pressure suction end 12, to form a sealed space 19 between chip 13 and substrate 1. Sealed space 19 communicates with the second injection port of pressurized filling end 11 and the second suction port 1212 of negative pressure suction end 12. Sealed space 19 ensures that filler adhesive 171 can be evenly distributed in the gap between chip 13 and substrate 1, preventing filler adhesive 171 from overflowing outside sealed space 19. In an optional embodiment of this embodiment, refer to Figure 1 and Figure 4The flexible sealing element 14 is disposed around the chip 13, located between the pressurized filling end 11 and the chip 13, and between the negative pressure suction end 12 and the chip 13, forming a sealed space 19 between the chip 13 and the substrate 1, thereby ensuring the integrity of the sealed space 19. This arrangement helps prevent the filler 171 from overflowing from the side of the chip 13 during the injection process. In another optional embodiment of this embodiment, referring to... Figure 1 and Figure 5 The flexible seal 14 is not only positioned around the chip 13, contacting the pressurized filling end 11 and the negative pressure suction end 12, but also located on the top of the chip 13. This arrangement prevents the filler 17 from contacting the top surface of the chip 13 when overfilled, thus avoiding potential damage or functional impairment. Optionally, the flexible seal 14 is made of silicone rubber, polytetrachloroethylene, or fluororubber. These materials possess good elasticity, chemical resistance, and temperature resistance, maintaining the shape and integrity of the flexible seal 14 during the filling of the filler 171 at the bottom of the chip, while ensuring a good seal in the enclosed space 19.

[0048] Reference Figure 1 , Figure 3 and Figure 6 The chip bottom filling structure also includes a filler cavity 15, which is an important component of the chip bottom filling structure and is used to store and provide filler adhesive 171. The filler cavity 15 is connected to the pressurized filling end 11 to inject filler adhesive 171 into the pressurized filling end 11. In an optional embodiment of this example, the filler cavity 15 and the pressurized filling end 11 are arranged adjacent to and connected to each other, so that the filler adhesive 171 can directly enter the sealed space 19 from the filler cavity 15 through the pressurized filling end 11 without the need for additional delivery pipes or equipment. The filler adhesive container 17 is disposed in the filler cavity 15. The filler adhesive container 17 includes a piston 172 and an opening 173. The piston 172 can move inside the filler adhesive container 17, and the opening 173 is the channel for the filler adhesive 171 to flow out of the filler adhesive container 17. The filler adhesive container 17 is filled with filler adhesive 171. This design of the filler container 17 allows for control of the flow of filler 171 by the movement of piston 172. As piston 172 moves forward inside the filler container 17, it compresses the filler 171, causing it to flow out through opening 173. This design ensures that the filler can be injected into the pressurized filling end 11 in a controllable manner. Opening 173 communicates with the pressurized filling end 11 to allow the filler 171 to flow into it. This design offers advantages such as simple structure, convenient operation, and controllable filling effect. It allows engineers to control the injection volume and speed of filler 171, achieving uniform filling of the chip bottom filling structure.

[0049] ReferenceFigures 1 to 6 The chip bottom filling structure of this application, by setting at least two pressurized filling ends 11 and a negative pressure suction end 12, and the pressurized filling ends 11 and the negative pressure suction end 12 are not connected to each other, realizes that multiple pressurized filling ends 11 can simultaneously inject filling adhesive 171 into the sealed space 19 of the chip bottom filling structure, and can simultaneously suck up excess filling adhesive 171. It can also control the injection speed and pressure of filling adhesive 171, thus solving the problems of slow filling speed and easy generation of adhesive voids in the chip bottom filling structure.

[0050] Example 2

[0051] Reference Figure 7 This embodiment provides a chip underfill system, which includes the chip underfill structure described in Embodiment 1. The chip underfill system also includes a negative pressure module, a positive pressure module, and a flow control device. The positive pressure module is connected to the pressurized filling end of the chip underfill structure to create positive pressure within the sealed space between the chip and the substrate. In this embodiment, the positive pressure module includes a pressure pump and a pressure control system. The pressure control system adjusts the pressure in real time and controls the pressure pump to uniformly inject the filler adhesive from multiple pressurized filling ends into the sealed space, improving the filling efficiency of the chip underfill structure and avoiding voids in the adhesive. The flow control device is connected to the positive pressure module to control the amount of filler adhesive injected into the sealed space, further preventing voids in the adhesive during the filling process. The negative pressure module is connected to the negative pressure suction end of the chip underfill structure to create negative pressure within the sealed space between the chip and the substrate. In this embodiment, the negative pressure module includes a vacuum pump and a vacuum control system. The vacuum pump extracts excess filler through the negative pressure suction end, and the vacuum control system adjusts the suction force in real time to ensure that excess filler can be effectively extracted and that the filler can be evenly distributed in the sealed space.

[0052] The chip underfill system disclosed in this application is a highly efficient and precise system integrating multiple functional modules, including a negative pressure module, a positive pressure module, and a flow control device. This system can significantly improve the operational efficiency and quality of chip underfill structures.

[0053] Example 3

[0054] Reference Figure 8 This embodiment provides a chip underfill method, employing the chip underfill structure of Embodiment 1. The chip underfill method of this embodiment includes the following steps:

[0055] The chip bottom filling structure is placed on the substrate, so that a sealed space is formed between the chip and the substrate;

[0056] Positive pressure is applied to the sealed space through the pressurized filling end of the bottom filling structure of the chip to inject the filling adhesive into the sealed space;

[0057] Negative pressure is applied to the sealed space through the negative pressure suction end of the bottom filling structure of the chip to assist the filling adhesive in filling the sealed space and to absorb excess filling adhesive.

[0058] Specifically, in an optional embodiment of this example, the pressurized filling end of the chip bottom filling structure is connected to a positive pressure module. The positive pressure module applies positive pressure to the sealed space through the pressurized filling end of the chip bottom filling structure, uniformly injecting the filler into the sealed space, improving the filling efficiency of the filler and avoiding voids in the filler material. A flow control device is connected to the positive pressure module to monitor the injection speed and flow rate of the filler in real time and precisely adjust the injection speed and flow rate. Simultaneously, a negative pressure suction end is connected to a negative pressure module to assist the filler in filling the sealed space. When a certain amount of filler has been injected, the negative pressure module extracts the excess filler through the negative pressure suction end. In another optional embodiment of this example, the pressurized filling end of the chip bottom filling structure is connected to the positive pressure module. The positive pressure module applies positive pressure to the sealed space through the pressurized filling end of the chip bottom filling structure and injects the filling adhesive evenly into the sealed space. Then, the negative pressure suction end is connected to the negative pressure module to assist the filling adhesive in filling the sealed space. When the filling adhesive has been injected to a certain amount, the negative pressure module extracts the excess filling adhesive through the negative pressure suction end.

[0059] The chip bottom filling method of this application can be applied to the chip bottom filling structure in Embodiment 1, which solves the problems of slow filling speed and easy generation of voids in the adhesive material in the chip bottom filling structure.

[0060] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A chip bottom filling structure for injecting filler adhesive into the bottom of a chip fixed on a substrate, characterized in that, include: At least two pressurized filling ends are detachably disposed above the substrate and around the chip; The negative pressure suction end is detachably disposed on the substrate and forms a cavity with the pressurized filling end in a way that is connected end to end but not interconnected. A flexible sealing element is disposed at least around the chip, between the negative pressure suction end and the chip, and between the pressurized filling end and the chip, to form a sealed space between the chip and the substrate.

2. The chip bottom filling structure according to claim 1, characterized in that, The number of pressurized filling terminals is three, and the three pressurized filling terminals are respectively disposed on the three sides of the chip, and the three pressurized filling terminals are not connected to each other.

3. The chip bottom filling structure according to claim 1, characterized in that, Also includes: The adhesive filling cavity is connected to the pressurized filling end to inject the filling adhesive into the pressurized filling end.

4. The chip bottom filling structure according to claim 1, characterized in that, The flexible seal is also disposed on the top of the chip.

5. The chip bottom filling structure according to claim 1, characterized in that, The flexible seal is made of silicone rubber, polytetrachloroethylene, or fluororubber.

6. The chip bottom filling structure according to claim 1, characterized in that, The pressurized filling end includes a filling channel, a first injection port, and a second injection port. The first injection port and the second injection port are formed on the filling channel. The first injection port is connected to the external environment, and the second injection port is connected to the sealed space.

7. The chip bottom filling structure according to claim 1, characterized in that, The negative pressure suction end includes a suction channel, a first suction port, and a second suction port. The first suction port and the second suction port are formed on the suction channel. The first suction port is connected to the external environment, and the second suction port is connected to the sealed space.

8. The chip bottom filling structure according to claim 6, characterized in that, The first injection port is at least one circular hole.

9. A chip underfill system, characterized in that, include: The chip bottom filling structure includes the chip bottom filling structure according to any one of claims 1 to 8; A positive pressure module is connected to the pressurized filling end of the bottom filling structure of the chip to form a positive pressure in the sealed space between the chip and the substrate; A flow control device is connected to the positive pressure module to control the injection amount of filler adhesive in the sealed space; The negative pressure module is connected to the negative pressure suction end of the bottom filling structure of the chip to form a negative pressure in the sealed space between the chip and the substrate.

10. A method for filling the bottom of a chip, characterized in that, The chip underfill structure according to any one of claims 1 to 8, the chip underfill method includes the following steps: The chip bottom filling structure is placed on the substrate, so that a sealed space is formed between the chip and the substrate; Positive pressure is applied to the sealed space through the pressurized filling end of the bottom filling structure of the chip to inject the filling adhesive into the sealed space; Negative pressure is applied to the sealed space through the negative pressure suction end of the bottom filling structure of the chip to assist the filling adhesive in filling the sealed space and to absorb excess filling adhesive.

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