Flip chip packaging structure and preparation method thereof

Abstract

The invention relates to the technical field of chip packaging, and particularly discloses a flip chip packaging structure and a preparation method thereof, the flip chip packaging structure comprises a substrate, the lower end of the substrate is provided with a mounting groove, the outer side of the upper end of the substrate is uniformly provided with a plurality of through holes I, and the lower ends of the through holes I are communicated with the mounting groove; the welding plate is welded to the upper end of the base plate, then the connecting column at the lower end of the limiting plate sequentially penetrates through the second penetrating hole and the first penetrating hole and is fixedly bonded with the supporting plate, and the supporting plate is fixed in the mounting groove; the chip unit is placed in the limiting groove, the welding flux protruding block at the lower end of the chip unit is located at the upper end of the welding spot, and the chip unit is preliminarily fixed through the limiting part; glue is injected into the feeding port, flows in the channel and flows out through the discharging port, and the welding flux protruding blocks and the welding spots are fixed. And finally, reversely coating the packaging colloid on the outer side of the whole structure to complete packaging of the chip unit.

Description

Technical Field

[0001] This invention relates to the field of chip packaging technology, specifically to a flip chip packaging structure and its fabrication method. Background Technology

[0002] Currently, flip-chip technology is one of the core technologies in electronic device packaging, LED packaging, microsystem packaging, and power component packaging. It is a packaging technology that uses solder joints to connect wafers or chips to a carrier, substrate, or circuit board without the use of metal leads. Its main feature is that the circuit side of the chip faces down, and it is connected to metal pads or wires on the circuit board through tiny solder joints, thereby achieving circuit connection and packaging.

[0003] Traditional flip chip packaging involves first using a flow-through underfill process to encapsulate the chip, and then encapsulating it. Although materials and processes have been continuously improving, underfill remains one of the most time-consuming processes in the entire packaging process. To optimize the packaging process and reduce costs without compromising reliability, a molding underfill process has emerged. This process combines the flow-through underfill process with the encapsulation process. The molding filler can not only fill the gap between the chip and the substrate, but also encapsulate the entire chip. The advantage of the molding underfill process is that it integrates the underfill process with the molding process, thereby shortening the process time.

[0004] However, during the encapsulation process, the geometry of the chip and the solder bumps at the bottom can create significant resistance to the flow of the filler. Furthermore, the filler can flow randomly during the filling process, which can easily lead to air residue and affect the filling effect. Summary of the Invention

[0005] The purpose of this invention is to provide a flip-chip packaging structure and its fabrication method to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a flip-chip packaging structure, comprising: The substrate has a mounting groove at its lower end and several through holes evenly distributed on the outer side of its upper end. The lower end of each through hole is connected to the mounting groove. A limiting plate has a limiting groove at its upper end for limiting and supporting the chip unit. An operating hole is located at the lower end of the limiting plate, with its upper end communicating with the lower end of the limiting groove. A connecting post is fixedly installed at the lower end of the limiting plate, and a support plate is fixedly installed thereon through a through hole at the lower end of the connecting post. The upper end of the welding plate is fixed between the limiting plate and the substrate. Several solder joints are evenly fixed on the upper end of the welding plate. Several solder bumps are provided on one side of the chip unit. When the chip unit is located in the limiting groove, the solder bumps and solder joints are in contact.

[0007] Preferably, the upper end of the connecting column is fixed to the four sides of the lower end of the limiting plate, and the lower end of the connecting column passes through the first through hole and is bonded to the upper end of the support plate through the first adhesive layer. The support plate is orifice-shaped and fits against the inner wall of the inner end of the mounting groove. A sealing plate is provided at the outer end of the support plate and the sealing plate is fixed in the mounting groove by the adhesive layer.

[0008] Preferably, the sidewall of the welding plate is uniformly provided with a plurality of perforations corresponding to the first perforation, the second perforation is sleeved on the outer end of the connecting post, the lower end of the welding plate is welded to the upper end of the substrate through the welding layer, and the upper end of the welding plate is bonded to the lower end of the limiting plate through the adhesive layer.

[0009] Preferably, grooves are provided on the side walls at both the upper and lower ends of the limiting plate, and the grooves are in the shape of an opening.

[0010] Preferably, a channel is fixedly installed inside the operating hole. The channel is S-shaped, and an inlet and an outlet are respectively opened on the left and right sides of one end of the limiting plate. The inlet and outlet are respectively connected to the left and right ends of the channel.

[0011] Preferably, when the welding plate is installed at the lower end of the limiting plate, the welding point is located inside the channel, and the height of the channel is less than the sum of the heights of the welding point and the solder bump.

[0012] Preferably, when the chip unit is placed in the limiting groove, the upper end of the chip unit is located outside the limiting plate and is fixed by the limiting component.

[0013] Preferably, the limiting component includes an elastic plate and a pressure ring, and there are multiple elastic plates and pressure rings. One end of the elastic plate is fixed to the side wall on the upper side of the outer end of the limiting plate, and the other end of the elastic plate is fixed to the outer wall of one end of the pressure ring. When the elastic plate is in a balanced state, the pressure ring is located above the limiting plate, and the side of the pressure ring away from the elastic plate is located above the limiting groove.

[0014] Preferably, the chip unit is squeezed by a pressure ring, which causes the elastic plate to deform and enter the limiting groove, while the lower end of the pressure ring abuts against the outer side of the upper end of the chip unit.

[0015] A method for fabricating a flip-chip package, applied to a flip-chip package structure, specifically includes the following steps: S1. First, weld the welding plate to the upper end of the substrate. Then, pass the connecting post at the lower end of the limiting plate through the second through hole and the first through hole in sequence and fix the support plate. Then fix the support plate in the mounting groove. S2. Then, place the chip unit in the limiting groove, so that the solder bump at its lower end is located at the upper end of the solder joint, and use the limiting component to initially fix the chip unit. S3. Next, by injecting glue into the inlet, the glue flows in the channel and flows out through the outlet, fixing the solder bump and solder joint. S4. Finally, the encapsulating colloid is applied to the outside of the entire structure to complete the encapsulation of the chip unit 21.

[0016] Compared with the prior art, the beneficial effects of the present invention are: This invention involves welding a welding plate to the upper end of a substrate, then passing the connecting post at the lower end of a limiting plate through perforation two and perforation one in sequence and fixing and bonding a support plate, which is then fixed in the mounting groove. The chip unit is placed in the limiting groove, with the solder bump at its lower end positioned above the solder joint, and the chip unit is initially fixed by the limiting component. Adhesive is injected into the inlet, flows through the channel, and exits through the outlet, fixing the solder bump and solder joint. Finally, encapsulating adhesive is applied to the outer side of the entire structure to complete the encapsulation of the chip unit. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the overall exploded structure of the present invention; Figure 3 This is a schematic diagram of the second exploded structure of the overall structure of the present invention; Figure 4 This is a schematic diagram of the inner end structure of the limiting plate of the present invention; Figure 5 This is a schematic cross-sectional view of the overall structure of the present invention; Figure 6 For the present invention Figure 5 Enlarged view of the structure of region A in the middle.

[0018] In the diagram: 1. Substrate; 2. Through-hole 1; 3. Mounting groove; 4. Limiting plate; 5. Connecting post; 6. Adhesive layer 1; 7. Support plate; 8. Sealing plate; 9. Limiting groove; 10. Operating hole; 11. Channel; 12. Inlet; 13. Outlet; 14. Elastic plate; 15. Pressure ring; 16. Welding plate; 17. Through-hole 2; 18. Welding layer; 19. Adhesive layer 2; 20. Solder joint; 21. Chip unit; 22. Solder bump; 23. Groove. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. 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.

[0020] Please see Figures 1-6 This invention provides a technical solution: a flip-chip packaging structure, comprising: a substrate 1, a mounting groove 3 at the lower end of the substrate 1, and a plurality of through holes 2 evenly distributed on the outer side of the upper end of the substrate 1, the lower ends of the through holes 2 communicating with the mounting groove 3; a limiting plate 4 having a limiting groove 9 at its upper end, the limiting groove 9 being used to limit and support the chip unit 21; and an operating hole 10 at the lower end of the limiting plate 4, the upper end of the operating hole 10 communicating with the lower end of the limiting groove 9, and a through hole 10 being fixedly installed within the operating hole 10. Channel 11 is S-shaped. One end of the limiting plate 4 has an inlet 12 and an outlet 13 on the left and right sides respectively. The inlet 12 and the outlet 13 are connected to the left and right ends of the channel 11 respectively. The inlet 12 is used to inject glue, and the outlet 13 is used to expel air in the channel 11, so that the glue flows more smoothly and avoids the formation of air bubbles in the glue. By injecting glue into the inlet 12, the glue flows in the channel 11 and flows out through the outlet 13, fixing the solder bump 22 and the solder joint 20.

[0021] A connecting post 5 is fixedly installed at the lower end of the limiting plate 4. The lower end of the connecting post 5 passes through the through hole 2 and is fixedly installed with a support plate 7. The upper end of the connecting post 5 is fixed to the four sides of the lower end of the limiting plate 4. After passing through the through hole 2, the lower end of the connecting post 5 is bonded to the upper end of the support plate 7 through the adhesive layer 6. The support plate 7 is orifice-shaped and fits against the inner wall of the inner end of the mounting groove 3. A sealing plate 8 is provided at the outer end of the support plate 7. The sealing plate 8 is fixed in the mounting groove 3 by the adhesive layer, thus fixing the support plate 7. The support plate 7 is used to support the limiting plate 4 and prevent the limiting plate 4 from deforming due to high temperature during welding, which would lead to poor welding.

[0022] The upper and lower ends of the limiting plate 4 are provided with grooves 23. The grooves 23 are in the shape of an opening. When the limiting plate 4 expands at high temperature, the grooves 23 can prevent the limiting plate 4 from deforming when it expands due to heat, thus avoiding false welding and improving the welding quality.

[0023] The upper end of the welding plate 16 is fixed between the limiting plate 4 and the substrate 1. Several solder joints 20 are uniformly fixedly installed on the upper end of the welding plate 16. Several through holes 17 corresponding to through holes 1 2 are uniformly opened on the side wall of the welding plate 16. The through holes 17 are sleeved on the outer end of the connecting post 5. The lower end of the welding plate 16 is welded to the upper end of the substrate 1 through the welding layer 18. The upper end of the welding plate 16 is bonded to the lower end of the limiting plate 4 through the adhesive layer 19 to fix the welding plate 16 and prevent the welding plate 16 from deforming due to heat. Several solder bumps 22 are provided on one side of the chip unit 21. When the chip unit 21 is located in the limiting groove 9, the solder bumps 22 and the solder joints 20 are in contact and can be welded.

[0024] When the welding plate 16 is installed at the lower end of the limiting plate 4, the solder joint 20 is located in the channel 11, and the height of the channel 11 is less than the sum of the heights of the solder joint 20 and the solder bump 22, so that the solder bump 22 has enough space to contact the solder joint 20.

[0025] When the chip unit 21 is placed in the limiting groove 9, the upper end of the chip unit 21 is located outside the limiting plate 4 and is fixed by the limiting component, which includes an elastic plate 14 and a pressure ring 15. Several elastic plates 14 and pressure rings 15 are provided. One end of the elastic plate 14 is fixed to the side wall of the upper side of the outer end of the limiting plate 4, and the other end of the elastic plate 14 is fixed to the outer wall of one end of the pressure ring 15. When the elastic plate 14 is in a balanced state, the pressure ring 15 is located above the limiting plate 4, and the side of the pressure ring 15 away from the elastic plate 14 is located above the limiting groove 9. The chip unit 21 squeezes the pressure ring 15 and causes the elastic plate 14 to deform and enter the limiting groove 9. At the same time, the lower end of the pressure ring 15 abuts against the outer side of the upper end of the chip unit 21, applying a downward pushing force to the chip unit 21, so that the solder bump 22 and the solder joint 20 are in more stable contact.

[0026] In actual use, the welding plate 16 is welded to the upper end of the substrate 1, and then the connecting post 5 at the lower end of the limiting plate 4 is passed through the second through hole 17 and the first through hole 2 in sequence and the support plate 7 is fixed and bonded, and the support plate 7 is fixed in the mounting groove 3; the chip unit 21 is placed in the limiting groove 9, so that the solder bump 22 at its lower end is located at the upper end of the solder joint 20, and the chip unit 21 is initially fixed by the limiting component; then, glue is injected into the feed port 12, the glue flows in the channel 11 and flows out through the discharge port 13, fixing the solder bump 22 and the solder joint 20; finally, the encapsulating glue is applied to the outside of the entire structure to complete the encapsulation of the chip unit 21.

[0027] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

[0028] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

Claims

1. A flip-chip packaging structure, characterized in that: include: The substrate (1) has a mounting groove (3) at its lower end and several through holes (2) are evenly distributed on the outer side of the upper end of the substrate (1). The lower end of the through holes (2) is connected to the mounting groove (3). A limiting plate (4) has a limiting groove (9) at its upper end, which is used to limit and support the chip unit (21). An operating hole (10) is provided at the lower end of the limiting plate (4), and the upper end of the operating hole (10) is connected to the lower end of the limiting groove (9). A connecting post (5) is fixedly installed at the lower end of the limiting plate (4), and the lower end of the connecting post (5) passes through the through hole (2) and is fixedly installed with a support plate (7). The upper end of the welding plate (16) is fixed between the limiting plate (4) and the substrate (1). Several solder joints (20) are uniformly fixed on the upper end of the welding plate (16). Several solder bumps (22) are provided on one side of the chip unit (21). When the chip unit (21) is located in the limiting groove (9), the solder bumps (22) and the solder joints (20) are in contact.

2. The flip-chip packaging structure according to claim 1, characterized in that: The upper end of the connecting column (5) is fixed to the four sides of the lower end of the limiting plate (4). The lower end of the connecting column (5) passes through the first through hole (2) and is bonded to the upper end of the support plate (7) through the first adhesive layer (6). The support plate (7) is in the shape of an opening. The support plate (7) is attached to the inner wall of the inner end of the mounting groove (3). The outer end of the support plate (7) is provided with a sealing plate (8). The sealing plate (8) is fixed in the mounting groove (3) by the adhesive layer.

3. The flip-chip packaging structure according to claim 1, characterized in that: The sidewall of the welding plate (16) is evenly provided with several perforations (17) corresponding to the first perforation (2). The second perforation (17) is sleeved on the outer end of the connecting post (5). The lower end of the welding plate (16) is welded to the upper end of the substrate (1) through the welding layer (18). The upper end of the welding plate (16) is bonded to the lower end of the limiting plate (4) through the adhesive layer (19).

4. The flip-chip packaging structure according to claim 1, characterized in that: The limiting plate (4) has grooves (23) on the side walls at both the upper and lower ends, and the grooves (23) are in the shape of an opening.

5. The flip-chip packaging structure according to claim 1, characterized in that: The operating hole (10) is fixedly installed with a channel (11), which is S-shaped. The left and right sides of one end of the limiting plate (4) are respectively provided with a feed inlet (12) and a discharge outlet (13), which are connected to the left and right ends of the channel (11).

6. The flip-chip packaging structure according to claim 1, characterized in that: When the welding plate (16) is installed at the lower end of the limiting plate (4), the welding point (20) is located in the channel (11), and the height of the channel (11) is less than the sum of the heights of the welding point (20) and the solder bump (22).

7. The flip-chip packaging structure according to claim 1, characterized in that: When the chip unit (21) is placed in the limiting groove (9), the upper end of the chip unit (21) is located outside the limiting plate (4) and is fixed by the limiting component.

8. A flip-chip packaging structure according to claim 6, characterized in that: The limiting component includes an elastic plate (14) and a pressure ring (15). There are several elastic plates (14) and pressure rings (15). One end of the elastic plate (14) is fixed on the side wall of the upper outer end of the limiting plate (4), and the other end of the elastic plate (14) is fixed on the outer wall of one end of the pressure ring (15). When the elastic plate (14) is in a balanced state, the pressure ring (15) is located above the limiting plate (4), and the side of the pressure ring (15) away from the elastic plate (14) is located above the limiting groove (9).

9. A flip-chip packaging structure according to claim 8, characterized in that: The chip unit (21) squeezes the pressure ring (15) and causes the elastic plate (14) to deform and enter the limiting groove (9), while the lower end of the pressure ring (15) and the outer side of the upper end of the chip unit (21) abut against each other.

10. A method for fabricating a flip-chip package, applied to the flip-chip package structure described in any one of claims 1-9, characterized in that: Specifically, the steps include the following: S1. First, weld the welding plate (16) to the upper end of the substrate (1), then pass the connecting post (5) at the lower end of the limiting plate (4) through the second through hole (17) and the first through hole (2) in sequence, and fix the adhesive support plate (7), and fix the support plate (7) in the mounting groove (3). S2. Then, place the chip unit in the limiting groove (9), so that the solder bump (22) at its lower end is located at the upper end of the solder joint (20), and fix the chip unit (21) in the initial stage by the limiting component. S3. Next, by injecting glue into the feed port (12), the glue flows in the channel (11) and flows out through the discharge port (13), fixing the solder bump (22) and the solder joint (20); S4. Finally, the encapsulating colloid is applied to the outside of the entire structure to complete the encapsulation of the chip unit (21).

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