A redistribution layer and packaging structure

Abstract

The application relates to the technical field of semiconductor packaging, in particular to a redistribution layer and a packaging structure, which comprises a redistribution layer GND body and a grounding structure; the grounding structure comprises a starting section and an extension section; the first end of the starting section is connected with the extension section, and the second end is used for being connected with the redistribution layer GND body; the width of the starting section gradually increases from the first end to the second end; one end of the extension section is connected with the starting section, and the other end extends in a direction away from the redistribution layer GND body. The application effectively suppresses resonance, reduces insertion loss and improves the transmission quality of high-frequency signals by improving the starting section of the redistribution layer.

Description

Technical Field

[0001] This application relates to the field of semiconductor packaging technology, and more specifically, to a redistribution layer and packaging structure. Background Technology

[0002] In the field of high-frequency electronic packaging technology, especially in fan-out wafer-level packaging for millimeter-wave bands, redistribution layers (RDLs) are widely used to realize electrical connections between chip I / O pads and external package interconnects.

[0003] In existing redistribution layers, the redistribution layer is typically designed as a long strip conductor of constant width, with its initial segment directly connected to the chip's ground pad or via structure, and then extending to the package area with a fixed width. However, when the signal frequency reaches 35GHz, the impedance discontinuity between this long strip ground starting segment and the GND body of the redistribution layer can induce significant electromagnetic resonance. This resonance causes signal energy to be reflected or absorbed at specific frequency points, severely degrading transmission performance. Experimental data shows that at 35GHz, the insertion loss of the RDL line using a traditional long strip ground structure is as high as -0.29dB, indicating significant energy loss during signal transmission. Furthermore, the presence of resonance also reduces signal integrity, limiting the high-frequency performance and reliability of the packaged product. Utility Model Content

[0004] The purpose of this application is to provide a redistribution layer and packaging structure that effectively suppresses resonance and reduces insertion loss by improving the start section of the redistribution layer, thereby improving the transmission quality of high-frequency signals.

[0005] This application is implemented as follows: On one hand, this application provides a redistribution layer, including a redistribution layer GND body and a grounding structure; the grounding structure includes a starting segment and an extension segment; a first end of the starting segment is connected to the extension segment, and a second end is used to connect to the redistribution layer GND body; the width of the starting segment gradually increases from the first end to the second end; one end of the extension segment is connected to the starting segment, and the other end extends away from the redistribution layer GND body.

[0006] As an optional implementation, the starting segment includes a trapezoidal structure; the short side of the trapezoidal structure is connected to the extension segment, and the long side is connected to the GND body of the redistribution layer.

[0007] As an optional implementation, the extension includes a first solder ball pad connected to the starting segment; the diameter of the first solder ball pad is smaller than the width of the second end of the starting segment.

[0008] As an optional implementation, there are at least two first solder ball pads spaced apart along the extension path of the extension segment, and a strip-shaped connection is provided between adjacent first solder ball pads.

[0009] As an optional implementation, two grounding structures are connected to the GND body of the redistribution layer.

[0010] As an optional implementation, the two grounding structures are located on the same side of the redistribution layer GND body; or, the two grounding structures are located on opposite sides of the redistribution layer GND body.

[0011] As an optional implementation, the GND redistribution layer has a second solder ball pad and a signal terminal connected to the second solder ball pad; the signal terminal is used to connect to the chip.

[0012] Secondly, this application provides a packaging structure including a chip, a passivation layer, and the aforementioned redistribution layer; the redistribution layer is disposed on the surface of the chip, and the passivation layer covers the redistribution layer.

[0013] The beneficial effects of this application include: The redistribution layer and encapsulation structure provided in this application effectively solve the electromagnetic resonance problem caused by impedance discontinuity in the millimeter-wave band (such as 35GHz) by employing a grounding structure with a gradually wide initial segment in the redistribution layer, significantly improving high-frequency signal transmission performance. This structure optimizes the impedance matching between the grounding path and the GND body of the redistribution layer through a smooth transition from narrow to wide, reducing local capacitance concentration effects and suppressing signal reflection and energy loss. Experiments show that at 35GHz, compared to the insertion loss of up to -0.29dB of the traditional structure, the gradually widened grounding design of this application can significantly reduce loss, improve signal integrity, and enhance electromagnetic compatibility and high-frequency stability. Attached Figure Description

[0014] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is one of the structural schematic diagrams of the redistribution layer in an embodiment of this application; Figure 2 This is a second schematic diagram of the redistribution layer in an embodiment of this application; Figure 3This is a schematic diagram of the packaging structure according to an embodiment of this application; Figure 4 The insertion loss is obtained from tests using existing technology; Figure 5 The insertion loss was obtained by testing in an embodiment of this application.

[0016] Icons: 100-Redundancy layer GND body; 101-Grounding structure; 102-Starting segment; 103-Extension segment; 104-Trapezoidal structure; 105-First solder ball pad; 106-Strip connection part; 107-Second solder ball pad; 108-Signal terminal; 10-Chip; 20-Passivation layer; 30-Redundancy layer. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0018] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0019] It should be noted that similar reference numerals 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. Furthermore, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0020] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0021] In the field of high-frequency electronic packaging technology, especially in fan-out wafer-level packaging for millimeter-wave bands, redistribution layers (RDLs) are widely used to realize electrical connections between chip pads and external package interconnects.

[0022] In existing redistribution layers, the redistribution layer is typically designed as a long strip conductor of constant width, with its initial segment directly connected to the chip's ground pad or via structure, and then extending to the package area with a fixed width. However, when the signal frequency reaches 35GHz, the impedance discontinuity between this long strip ground starting segment and the redistribution layer GND body 100 can induce significant electromagnetic resonance. This resonance causes signal energy to be reflected or absorbed at specific frequency points, severely degrading transmission performance. Experimental data shows that at 35GHz, the insertion loss of the RDL line using a traditional long strip ground structure is as high as -0.29dB, indicating significant energy loss during signal transmission. Furthermore, the presence of resonance also reduces signal integrity, limiting the high-frequency performance and reliability of the packaged product.

[0023] To address the aforementioned technical problems, embodiments of this application provide a redistribution layer and a packaging structure.

[0024] Reference Figure 1 , Figure 2 As shown, this application provides a redistribution layer 30, including a redistribution layer GND body 100 and a grounding structure 101; the grounding structure 101 includes a starting segment 102 and an extension segment 103; a first end of the starting segment 102 is connected to the extension segment 103, and a second end is used to connect to the redistribution layer GND body 100; the width of the starting segment 102 gradually increases from the first end to the second end; one end of the extension segment 103 is connected to the starting segment 102, and the other end extends away from the redistribution layer GND body 100.

[0025] It should be noted that, in this embodiment of the application, the electromagnetic resonance problem caused by impedance discontinuity at high frequencies is solved by optimizing the geometry of the grounding structure 101 in the redistribution layer 30, thereby improving the signal transmission performance in the millimeter-wave band.

[0026] It should be noted that the traditional grounding structure 101 adopts a uniform width elongated strip design. The abrupt change in distributed parameters between it and the redistribution layer GND body 100 leads to significant impedance mismatch and parasitic resonance at high frequencies, causing signal reflection and insertion loss. This application designs the starting segment 102 of the grounding structure 101 as a gradually widening shape (such as a trapezoid or fan shape) from the connection end to the redistribution layer GND body 100. This structure achieves a smoother impedance transition between the grounding path and the redistribution layer GND body 100, effectively reducing the local capacitance concentration effect and suppressing electromagnetic resonance. Simultaneously, the extension segment 103 extends from the starting segment 102 and away from the redistribution layer GND body 100, further weakening the non-ideal coupling of the ground wire to the redistribution layer GND body 100. Through the synergistic effect of these structures, the electromagnetic matching characteristics at high frequencies are significantly improved, signal energy loss is reduced, and the signal integrity of the redistribution layer 30 and the electrical performance and reliability of the packaging structure in the millimeter-wave band are enhanced.

[0027] This application embodiment effectively solves the electromagnetic resonance problem caused by impedance discontinuity in the millimeter-wave band (such as 35GHz) by employing a grounding structure 101 with a gradually widening start segment 102 in the redistribution layer 30, significantly improving high-frequency signal transmission performance. This structure, through a smooth transition from narrow to wide, optimizes the impedance matching between the grounding path and the GND body 100 of the redistribution layer, reduces local capacitance concentration effects, and suppresses signal reflection and energy loss. Experiments show that at the 35GHz frequency, compared to the insertion loss of up to -0.29dB of the traditional structure, the gradually widening grounding design of this application can significantly reduce loss, improve signal integrity, and enhance electromagnetic compatibility and high-frequency stability.

[0028] like Figure 4 As shown, the grounding structure of the redistribution layer in the prior art is prone to antenna effect, which causes resonance to the intermediate high-speed signal. After testing, this resonance caused the insertion loss of the high-speed signal to be -0.29dB at 33.54GHz, which degraded the signal transmission quality.

[0029] like Figure 5 As shown, after changing the shape, the resonance of the high-speed signal in the middle disappears at 35 GHz, the insertion loss changes from -0.29 dB to -0.17 dB, and the signal transmission quality is improved.

[0030] Therefore, this technical solution significantly improves the electrical performance and reliability of fan-out wafer-level packaging in high-frequency and high-speed applications without increasing process complexity, and has good practicality and industrialization prospects.

[0031] Reference Figure 1 , Figure 2As shown, in one optional implementation, the starting segment 102 includes a trapezoidal structure 104; the short side of the trapezoidal structure 104 is connected to the extension segment 103, and the long side is connected to the redistribution layer GND body 100.

[0032] For example, the trapezoidal structure 104 has an upper base length of approximately 190 μm, a lower base length of approximately 350 μm, and a height of approximately 200 μm.

[0033] The trapezoidal structure 104 can be formed by copper plating or silver plating.

[0034] It should be noted that this application designs the starting segment 102 of the grounding structure 101 as a trapezoid, wherein the short side of the trapezoid connects to the extension segment 103, and the long side connects to the redistribution layer GND body 100. This geometric configuration achieves a continuous change in impedance of the grounding path through a gradual transition from narrow to wide. The technical principle is as follows: During high-frequency signal transmission, the distributed capacitance and inductance between the redistribution layer GND body 100 and the ground wire are extremely sensitive to the geometry. The conventional equal-width grounding structure 101 forms an abrupt electromagnetic boundary at the connection point, leading to impedance mismatch and local electric field concentration, which triggers electromagnetic resonance in the 35GHz band. In contrast, the wide side of the trapezoidal starting segment 102 is close to the redistribution layer GND body 100, increasing the near-end grounding area and enhancing the grounding coupling capability. At the same time, its width gradually decreases along the signal propagation direction, forming a smooth impedance gradient, effectively dispersing the capacitance distribution and suppressing the excitation of resonant modes. The extension 103 extends from the short side of the trapezoid and moves away from the GND body 100 of the redistribution layer, further avoiding excessive interference from the ground line to the signal path. This structure significantly improves electromagnetic matching characteristics at high frequencies, reduces insertion loss, and enhances signal integrity and the high-frequency performance of the package without adding extra materials or process steps.

[0035] Reference Figure 1 , Figure 2 As shown, in one optional implementation, the extension 103 includes a first solder ball pad 105, which is connected to the starting segment 102; the diameter of the first solder ball pad 105 is smaller than the width of the second end of the starting segment 102.

[0036] It should be noted that in this application, the extension segment 103 includes a first solder ball pad 105, which is connected to the starting segment 102. The diameter of the first solder ball pad 105 is smaller than the width of the second end of the starting segment 102 (i.e., the end near the GND body 100 of the redistribution layer). This design optimizes the high-frequency electromagnetic field distribution while ensuring electrical continuity. The starting segment 102 adopts a gradually widening structure (such as a trapezoid) to provide a larger grounding area on the side near the GND body 100 of the redistribution layer, thereby enhancing local grounding capability and improving impedance matching, suppressing electromagnetic resonance in the 35GHz band. Meanwhile, the first solder ball pad 105 connected to the extension segment 103 has a smaller diameter, forming an asymmetrical structure. This structure avoids the introduction of additional parasitic capacitance due to excessively large pad size, which would cause strong coupling with the GND body 100 of the redistribution layer. Furthermore, it allows the current to smoothly transition from the wide starting segment 102 to the smaller pad, reducing electromagnetic field abrupt changes and reflections. Simultaneously, the small pad size helps save wiring space and increase package density. This structure balances high-frequency signal integrity and package integration without sacrificing grounding performance, further improving the transmission performance and reliability of the redistribution layer 30 in the millimeter-wave band.

[0037] Reference Figure 1 , Figure 2 As shown, as an optional implementation, there are at least two first solder ball pads 105 arranged at intervals along the extension path of the extension segment 103, and a strip-shaped connecting portion 106 is provided between adjacent first solder ball pads 105.

[0038] It should be noted that this application provides at least two first solder ball pads 105 arranged at intervals along their extension path on the extension section 103, and the adjacent pads are connected by a strip connection portion 106 to form a distributed grounding path.

[0039] This embodiment of the application, while ensuring grounding continuity, achieves multi-point grounding through multiple spaced first solder ball pads 105, effectively reducing the equivalent inductance of the grounding path and dispersing high-frequency current density, suppressing inductive resonance and electromagnetic coupling caused by a single long path. The strip-shaped connector 106 connects the pads in series, forming a low-impedance conduction channel, enabling stable transmission of grounding current along a predetermined path. Simultaneously, since the diameter of each first solder ball pad 105 is smaller than the width of the second end of the starting segment 102, local capacitance concentration is avoided, reducing parasitic effects on the adjacent redistribution layer GND body 100. This distributed structure also enhances process redundancy; even if individual pads have defects, current can still be indirectly conducted through the connector, improving grounding reliability. Overall, this design optimizes impedance continuity and electromagnetic distribution at high frequencies (e.g., 35GHz), further reducing insertion loss and improving signal integrity, making it suitable for high-density, high-performance millimeter-wave package redistribution layers 30.

[0040] Reference Figure 1As shown, as an optional implementation, two grounding structures 101 are connected to the redistribution layer GND body 100.

[0041] It should be noted that two grounding structures 101 are connected to the GND body 100 of the redundancy layer. This design, by symmetrically or asymmetrically arranging dual grounding paths on both sides of the GND body 100, forms a more complete reference ground environment, thereby effectively improving the stability and integrity of high-frequency signal transmission. The technical principle is as follows: In the millimeter-wave frequency band (e.g., 35GHz), the electromagnetic field distribution around the GND body 100 of the redundancy layer is extremely sensitive to adjacent grounding structures. Single-sided grounding easily leads to electromagnetic field asymmetry, common-mode noise, and impedance fluctuations. By setting two grounding structures 101, connected to different locations on the GND body 100 of the redundancy layer (e.g., both ends or the same / opposite sides), the electromagnetic shielding effect on the GND body 100 of the redundancy layer can be enhanced, reducing external interference and crosstalk. Simultaneously, the dual grounding paths provide lower loop inductance and a more uniform current return path, suppressing high-frequency resonance and ground bounce noise. Combined with the design of each grounding structure 101 using a gradually changing starting segment 102 in this application, the impedance matching at the two connection points is further optimized, reducing signal reflection. This solution significantly improves the electromagnetic performance of the redistribution layer 30 without significantly increasing wiring complexity, making it particularly suitable for applications with stringent signal integrity requirements in high-density, high-frequency packages.

[0042] For example, the two grounding structures 101 are located on the same side of the redistribution layer GND body 100; or, the two grounding structures 101 are located on opposite sides of the redistribution layer GND body 100.

[0043] Reference Figure 1 As shown, as an optional implementation, the GND body 100 of the redistribution layer is provided with a second solder ball pad 107 and a signal terminal 108 connected to the second solder ball pad 107; the signal terminal 108 is used to connect to the chip 10.

[0044] It should be noted that the GND body 100 of the redistribution layer is provided with a second solder ball pad 107 and a signal terminal 108 connected thereto. The signal terminal 108 is used to realize the electrical connection with the chip pad, and the second solder ball pad 107 serves as the output node for external package interconnection.

[0045] In this embodiment, the output signal of chip 10 is introduced into redistribution layer 30 through signal terminal 108 and transmitted to external package (such as substrate or PCB) via second solder ball pad 107, completing the electrical connection between chip 10 and external circuit. Combined with the optimized design of this application, the grounding structure 101 with a gradient start segment 102 can be symmetrically or asymmetrically configured on both sides of the redistribution layer GND body 100, so that the second solder ball pad 107 and its connection path are in a good reference ground environment, effectively controlling the signal return path and reducing loop inductance and electromagnetic radiation.

[0046] Meanwhile, the second solder ball pad 107, as a key interconnect node, is designed with appropriate size and position to avoid excessive coupling with the adjacent ground line or the GND body 100 of the redistribution layer, further improving impedance continuity and signal integrity at high frequencies (such as 35GHz). This solution achieves efficient and low-loss transmission from the chip 10 to the package, enhancing the reliability and integration capability of the redistribution layer 30 in millimeter-wave applications.

[0047] Reference Figure 3 As shown, this application provides a packaging structure including a chip 10, a passivation layer 20, and the aforementioned redistribution layer 30; the redistribution layer 30 is disposed on the surface of the chip 10, and the passivation layer 20 covers the redistribution layer 30.

[0048] The packaging structure provided in this application includes a chip 10, a passivation layer 20, and the optimized redistribution layer 30 described above. The passivation layer 20 and the redistribution layer 30 are deposited on the surface of the chip 10. The passivation layer 20 covers the redistribution layer 30 to protect the circuit, block moisture and contaminants, and provide mechanical support and stress buffering. The redistribution layer 30 is used to achieve high-density electrical interconnection between the chip pads and the external package. In this structure, the GND body 100 of the redistribution layer 30 is connected to the corresponding pad of the chip 10 through a conductive via or signal terminal 108. The starting segment 102 of the grounding structure 101 adopts a width-gradient design (such as a trapezoid), with its second end connected to the GND body 100 and its first end connected to an extension segment 103. The extension segment 103 further connects to one or more first solder ball pads 105 to achieve external connection of the grounding path. This integration method effectively suppresses impedance discontinuities and electromagnetic resonances caused by traditional equal-width grounding lines in the millimeter-wave frequency band (such as 35GHz), significantly reduces insertion loss, and improves signal integrity. Meanwhile, by setting a second solder ball pad 107 on the GND body 100 of the redistribution layer to connect to external circuits, combined with optimized layout such as the double grounding structure 101, the return path control and electromagnetic shielding effect of high-frequency signals are further enhanced. The overall package structure achieves excellent high-frequency electrical performance and long-term reliability while ensuring process compatibility and integration, making it particularly suitable for high-performance fan-out wafer-level packaging applications such as 5G communication and millimeter-wave radar.

[0049] The passivation layer 20 includes silicon dioxide, polyimide, etc.

[0050] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A redistribution layer, characterized in that, It includes a redistribution layer GND body (100) and a grounding structure (101); the grounding structure (101) includes a starting segment (102) and an extension segment (103); the first end of the starting segment (102) is connected to the extension segment (103), and the second end is used to connect to the redistribution layer GND body (100); the width of the starting segment (102) gradually increases from the first end to the second end; one end of the extension segment (103) is connected to the starting segment (102), and the other end extends away from the redistribution layer GND body (100).

2. The redistribution layer according to claim 1, characterized in that, The starting segment (102) includes a trapezoidal structure (104); the short side of the trapezoidal structure (104) is connected to the extension segment (103), and the long side is connected to the redistribution layer GND body (100).

3. The redistribution layer according to claim 1, characterized in that, The extension segment (103) includes a first solder ball pad (105) which is connected to the starting segment (102); the diameter of the first solder ball pad (105) is smaller than the width of the second end of the starting segment (102).

4. The redistribution layer according to claim 3, characterized in that, There are at least two first solder ball pads (105) arranged at intervals along the extension path of the extension section (103), and a strip connection (106) is provided between adjacent first solder ball pads (105).

5. The redistribution layer according to any one of claims 1-4, characterized in that, Two grounding structures (101) are connected to the GND body (100) of the redistribution layer.

6. The redistribution layer according to claim 5, characterized in that, The two grounding structures (101) are located on the same side of the redistribution layer GND body (100); or, the two grounding structures (101) are located on opposite sides of the redistribution layer GND body (100).

7. The redistribution layer according to any one of claims 1-4, characterized in that, The redistribution layer GND body (100) is provided with a second solder ball pad (107) and a signal terminal (108) connected to the second solder ball pad (107); the signal terminal (108) is used to connect to the chip (10).

8. A packaging structure, characterized in that, It includes a chip (10), a passivation layer (20), and a redistribution layer (30) as described in any one of claims 1-7; the redistribution layer (30) is disposed on the surface of the chip (10), and the passivation layer (20) covers the redistribution layer (30).

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