Millimeter wave chip package structure with stripline transition

Abstract

The application provides a millimeter wave chip packaging structure with a strip line transition, and relates to the technical field of millimeter wave chip packaging.The millimeter wave chip packaging structure comprises a millimeter wave chip, an antenna patch and a horizontally suspended strip line transition structure, the antenna patch is attached to a metal shielding layer, the millimeter wave chip is embedded in the horizontally suspended strip line transition structure, the output port of the chip is connected to one end of the strip line through a solder ball structure, and is interconnected with the patch antenna through a slot coupling effect.The chip is embedded in the upper layer of the horizontally suspended strip line transition structure in the embodiment of the application, unlike most flip chip structures, a vertical coaxial transition structure and a horizontal strip line transition are required, the embodiment of the application can realize the interconnection of the chip port and the antenna feed port by using only the horizontal transition structure, the vertical transition structure is avoided, the packaging structure complexity is reduced, high-frequency parasitic effects are reduced, and high-frequency loss is effectively reduced.

Description

Technical Field

[0001] This invention relates to the field of millimeter-wave chip packaging technology, and more specifically to a millimeter-wave chip packaging structure with a stripline transition. Background Technology

[0002] With the rapid development of 6G wireless communication technology, the demand for high-quality communication chips is becoming increasingly urgent. Taking the D-band (110–170 GHz) as an example, it has become one of the important candidate bands in the field of 6G wireless communication due to its advantages such as strong anti-interference capability, rich spectrum, and easy expansion. Since the operating wavelength of D-band chips can reach the millimeter level, it provides conditions for the integrated integration of chip to packaged antenna, thereby better balancing package size, performance, and cost, and better realizing microsystem-level wireless transmission functions.

[0003] In traditional chip-antenna integrated packaging, the transition structure used is usually a coaxial transition structure, which achieves low-loss transmission of electromagnetic waves through a relatively complex multi-layer via structure. However, because D-band millimeter-wave chips operate at higher frequencies and their wavelengths are close to the feed line length, electromagnetic parasitic effects are more likely to occur when electromagnetic waves are transmitted through a complex multi-layer via structure, resulting in high-frequency losses. Summary of the Invention

[0004] (a) Technical problems to be solved

[0005] To address the shortcomings of existing technologies, this invention provides a millimeter-wave chip packaging structure with a stripline transition, which solves the technical problem that existing packaging structures are prone to electromagnetic parasitic effects.

[0006] (II) Technical Solution

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] This invention provides a millimeter-wave chip packaging structure with a stripline transition, comprising: a millimeter-wave chip, an antenna patch, and a horizontally suspended stripline transition structure.

[0009] The horizontally suspended stripline transition structure comprises, from top to bottom: a metal shielding layer, a stripline layer, and a redistribution layer, with a dielectric layer between each layer; the stripline layer includes a horizontally suspended stripline.

[0010] The antenna patch is attached to the metal shielding layer;

[0011] The millimeter-wave chip is embedded in the horizontally suspended stripline transition structure. The chip's output port is connected to one end of the horizontally suspended stripline through a solder pad and solder ball structure, and is interconnected with the patch antenna through a slot coupling effect.

[0012] Preferably, the metal shielding layer includes a first metal layer and a second metal layer, with a dielectric layer disposed between the two metal layers.

[0013] Preferably, the encapsulation structure further includes metal shielding pillars that longitudinally penetrate the dielectric layer of the entire horizontally suspended strip transition structure and are arranged at equal intervals along the non-radiative direction.

[0014] Preferably, the millimeter-wave chip packaging structure includes multiple redistribution layers, with a dielectric layer disposed between the multiple redistribution layers.

[0015] Preferably, the millimeter-wave packaging structure further includes a bottom metal layer, which is located on the redistribution layer and a dielectric layer is disposed between the bottom metal layer and the redistribution layer.

[0016] Preferably, the stripline layer comprises a horizontally suspended stripline consisting of an electromagnetic signal transmission line in the middle and metal strips symmetrically distributed on both sides.

[0017] Preferably, the millimeter-wave chip packaging structure with stripline transition includes a single-channel stripline transition millimeter-wave chip packaging structure and a multi-channel stripline transition millimeter-wave chip packaging structure, corresponding to single and multiple horizontally suspended striplines, respectively.

[0018] When multiple horizontally suspended strips are included, the multiple horizontally suspended strips have a symmetrical structure and are of equal length.

[0019] Preferably, the multi-channel stripline transition millimeter-wave chip packaging structure includes multiple antenna patches, which are symmetrically distributed about the millimeter-wave chip.

[0020] Preferably, the dielectric layer is an LTCC dielectric layer.

[0021] (III) Beneficial Effects

[0022] This invention provides a millimeter-wave chip packaging structure with a stripline transition. Compared with the prior art, it has the following advantages:

[0023] The millimeter-wave chip packaging structure of the present invention includes a millimeter-wave chip, an antenna patch, and a horizontally suspended stripline transition structure. The horizontally suspended stripline transition structure, from top to bottom, comprises: a metal shielding layer, a stripline layer, and a redistribution layer, with a dielectric layer between each layer. The stripline layer includes a horizontally suspended stripline. The antenna patch is attached to the metal shielding layer. The millimeter-wave chip is embedded in the horizontally suspended stripline transition structure, and the chip's output port is connected to one end of the horizontally suspended stripline via a solder pad / ball structure and interconnected with the patch antenna through a slot coupling effect. This invention enables interconnection from the chip port to the antenna feed port using only the horizontal transition structure, avoiding the introduction of a vertical transition structure, reducing packaging complexity, minimizing high-frequency parasitic effects, and effectively reducing high-frequency losses. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 A 3D diagram of a millimeter-wave chip package structure with a single-channel stripline transition;

[0026] Figure 2 Side view of a single-channel millimeter-wave chip package structure based on LTCC stripline transition;

[0027] Figure 3 A 3D diagram of a single-channel millimeter-wave chip package structure based on LTCC stripline transition;

[0028] Figure 4 Side view of a multi-channel millimeter-wave chip package structure based on LTCC stripline transition;

[0029] Figure 5 Top view of a multi-channel millimeter-wave chip package structure based on LTCC stripline transition;

[0030] Figure 6 The S-parameters of a single-channel LTCC co-layer transition structure;

[0031] Figures 7a to 7d for Figure 4 The S-parameters of the multi-channel LTCC co-layer transition structure shown are as follows: Figure 7a The transmission loss between port 1 and port 5, and the S-parameters of port 1 and port 5; Figure 7b The transmission loss between port 2 and port 6, and the S-parameters of port 2 and port 6; Figure 7c The transmission loss between port 3 and port 7, and the S-parameters of port 3 and port 7; Figure 7d The transmission loss between port 4 and port 8; the S-parameters of port 4 and port 8.

[0032] Figure 8a , Figure 8b for Figure 4 The phase consistency of the multi-channel LTCC co-layer transition structure shown is as follows: Figure 8a For phase consistency between port 1 to port 5 and port 2 to port 6; Figure 8b Phase consistency between port 3 and port 7, and between port 4 and port 8. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. 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.

[0034] This application provides a millimeter-wave chip packaging structure with a stripline transition, which solves the technical problem that existing packaging structures are prone to electromagnetic parasitics, thereby reducing high-frequency parasitic effects, effectively reducing high-frequency loss, and improving transmission characteristics.

[0035] The technical solution in this application is to solve the above-mentioned technical problems, and the general idea is as follows:

[0036] Traditional flip-chip structures require vertical coaxial transition structures and horizontal stripline transitions, which are prone to electromagnetic parasitic effects. To reduce these parasitic effects and lower high-frequency transmission losses, this invention employs stripline transition technology. The output of the chip channel is connected to the redistribution layer of the stripline via a solder ball structure. Simultaneously, the feed port of the patch antenna is also implemented using the metal layer containing the stripline. High-quality interconnection from the chip output to the patch antenna is achieved through a horizontally suspended stripline transition structure and slot coupling technology. Unlike traditional quasi-coaxial transition structures, stripline transition technology avoids the introduction of vertical transition structures, reduces the structural complexity of the package interconnect, and effectively reduces high-frequency parasitic effects and high-frequency transmission losses. Furthermore, in traditional chip packaging processes, the packaging material used is typically plastic, and a thicker layer of plastic is applied above the chip to improve its physical performance. However, in millimeter-wave and even terahertz bands, the loss tangent of plastic materials is relatively large. Extensive use of such packaging materials will affect the radiation performance of the packaged antenna and reduce antenna gain. Furthermore, due to the high frequency of D-band electromagnetic waves, more complex electromagnetic shielding structures are required to suppress the propagation of electromagnetic waves in dielectric materials. In this invention, the molding compound in traditional packaging is replaced with LTCC (low-temperature co-fired ceramic), and multiple metal redistribution layers are implemented within the ceramic packaging dielectric layer. Because the ceramic material used has lower electromagnetic loss and higher processing precision in the D-band, it can effectively improve the performance of the chip-antenna microsystem.

[0037] This invention provides a millimeter-wave chip packaging structure with a stripline transition, such as... Figure 1 As shown, it includes: a millimeter-wave chip, an antenna patch, and a horizontally suspended stripline transition structure.

[0038] The horizontally suspended stripline transition structure comprises, from top to bottom: a metal shielding layer, a stripline layer, and a redistribution layer, with a dielectric layer between each layer.

[0039] The antenna patch is attached to the metal shielding layer, the millimeter-wave chip is embedded in the horizontally suspended stripline transition structure, and the chip's output port is connected to one end of the stripline through a solder pad and solder ball structure, and interconnected with the patch antenna through a slot coupling effect.

[0040] In this embodiment of the invention, the chip is embedded in the upper layer of a horizontally suspended stripline transition structure. Unlike most flip-chip structures, which require both a vertical coaxial transition structure and a horizontal stripline transition, this embodiment of the invention can achieve the interconnection from the chip port to the antenna feed port using only a horizontal transition structure. This avoids the introduction of a vertical transition structure, reduces the complexity of the packaging structure, reduces high-frequency parasitic effects, and effectively reduces high-frequency losses.

[0041] The embodiments of the present invention will be described in detail below through specific examples:

[0042] Example 1:

[0043] like Figure 2 , Figure 3 As shown, the embodiments of the present invention will be described in detail using a single-channel millimeter-wave chip packaging structure based on LTCC stripline transition. In this embodiment, the chip is a D-band millimeter-wave chip, and the horizontally suspended stripline transition structure includes, from top to bottom, a metal shielding layer, a stripline layer, and a redistribution layer, with an LTCC dielectric layer disposed between each layer.

[0044] in,

[0045] The stripline layer consists of a horizontally suspended stripline formed by a central electromagnetic signal transmission line and symmetrically distributed metal strips on both sides. The specific width of the transmission line, the width of the metal strips, and the distance between them are designed according to the performance characteristics of different frequency bands.

[0046] The metal shielding layer consists of a first metal layer and a second metal layer, with an LTCC dielectric layer disposed between the two metal layers. This double-metal layer structure can better suppress surface waves, reduce the reflection coefficient of electromagnetic waves at the port, and improve the stability of the microsystem structure and performance.

[0047] The packaging structure also includes metal shielding pillars that longitudinally penetrate the entire LTCC dielectric layer of the horizontally suspended stripline transition structure and are evenly spaced along the non-radiative direction, effectively suppressing the propagation of electromagnetic waves within the dielectric layer. It should be noted that the metal shielding pillars longitudinally penetrate all LTCC dielectric layers of the horizontally suspended stripline transition structure and are connected to the metal shielding layer and redistribution layer. Since the metal layers, redistribution layer, and metal pillars are made of the same material, their connection constitutes penetration; that is, the metal shielding pillars longitudinally penetrate the horizontally suspended stripline transition structure.

[0048] The transition from the chip output to the antenna feed uses a suspended stripline structure, where the chip pins are connected to one end of the stripline via pads and solder balls, and the other end of the stripline is connected to the patch antenna feed port via a slot coupling effect.

[0049] Figure 6 The S-parameters and transmission loss of the single-channel LTCC co-layer transition structure are shown. In the frequency range of 135-145GHz, the S-parameters of the single-channel LTCC co-layer transition structure are all less than -15dB, achieving good electromagnetic matching.

[0050] Example 2:

[0051] like Figure 4 , Figure 5As shown, the embodiments of the present invention are described in detail using a multi-channel millimeter-wave chip package structure based on LTCC stripline transition. The results are similar to those of the single-channel design. The chip is positioned in the middle, and multiple ports of the chip are connected to the corresponding packaged antenna feed ports via multiple suspended striplines. The multiple packaged antennas are symmetrically distributed about the chip, and the length of each suspended stripline transition structure is equal, thereby achieving power combining functionality on the packaged antennas. Furthermore, in this embodiment, multiple redistribution layers are implemented within the LTCC dielectric layer. Since the ceramic material used has low electromagnetic loss and high processing precision in the D-band, the operating performance of the chip-antenna microsystem can be effectively improved.

[0052] In practical implementation, the millimeter-wave packaging structure also includes a bottom metal layer used as a ground wire. This bottom metal layer is located at the bottom of the millimeter-wave packaging structure and is provided with an LTTC dielectric layer between it and the redistribution layer.

[0053] like Figure 5 The figures shown are a side view and a top view of the chip packaging structure based on multi-channel LTCC stripline transition technology. In order to achieve power combining, the chip-antenna integrated package adopts a 4-receive and 4-transmit center-symmetric structure, and sets the physical length of each feed line to be equal, so as to achieve the phase consistency of the electromagnetic signal at the antenna feed port.

[0054] like Figures 7a to 7d The diagram shows the S-parameters and transmission loss of the multi-channel LTCC co-layer transition structure. This chip-antenna integrated multi-channel package structure exhibits excellent performance in a high-frequency, wide-band range of 135-145 GHz. The effective reflection coefficients of each chip port and each antenna feed port are consistently below -15 dB, and the transmission loss of multiple feed lines at 140 GHz is less than 1.85 dB. Furthermore, as... Figure 8a , Figure 8b As shown, the phase imbalance of the multi-channel LTCC co-layer transition structure is always less than 15 degrees in the 135-145GHz frequency range, which meets the phase requirements for the antenna array to complete the power combining function.

[0055] In summary, compared with existing technologies, it has the following beneficial effects:

[0056] 1. In this embodiment of the invention, the chip is embedded in the upper layer of the horizontally suspended stripline transition structure. Unlike most flip-chip structures, which require a vertical coaxial transition structure and a horizontal stripline transition, this embodiment of the invention can achieve the interconnection from the chip port to the antenna feed port using only the horizontal transition structure, avoiding the introduction of a vertical transition structure, reducing the complexity of the packaging structure, reducing high-frequency parasitic effects, and effectively reducing high-frequency losses.

[0057] 2. In this embodiment of the invention, the plastic encapsulation material in the traditional packaging is replaced with LTCC material. Since the ceramic material used has lower electromagnetic loss and higher processing precision in the D band, it can effectively improve the working performance of the chip-antenna microsystem.

[0058] 3. In this embodiment of the invention, a multi-layer metal shielding layer and a plurality of metal shielding pillars are provided. A double-layer metal shielding layer structure is adopted in the LTCC packaging layer above the suspended stripline. A metal shielding pillar array is provided below the chip and around the stripline, and the pillars are arranged at equal intervals along the non-radiative direction, thereby effectively suppressing the propagation of electromagnetic waves in the dielectric layer.

[0059] 4. The embodiments of the present invention adopt a symmetrical multi-channel transition interconnection structure, from multiple ports of the chip to the corresponding packaged antenna feed ports through multiple horizontally suspended strip lines. The multiple packaged antennas are symmetrically distributed about the chip, and the length of each suspended strip line transition structure is equal, thereby achieving phase consistency of the electromagnetic signal at the antenna feed port.

[0060] 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. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0061] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A millimeter-wave chip packaging structure with a stripline transition, characterized in that, include: Millimeter-wave chip, antenna patch and horizontally suspended stripline transition structure, The horizontally suspended stripline transition structure comprises, from top to bottom: a metal shielding layer, a stripline layer, and a redistribution layer, with a dielectric layer between each layer; the stripline layer includes a horizontally suspended stripline. The antenna patch is attached to the metal shielding layer; The millimeter-wave chip is embedded in the horizontally suspended stripline transition structure. The chip's output port is connected to one end of the horizontally suspended stripline through a solder pad and solder ball structure, and is interconnected with the patch antenna through a slot coupling effect. The metal shielding layer includes a first metal layer and a second metal layer, with a dielectric layer disposed between the two metal layers; The stripline layer comprises a horizontally suspended stripline consisting of an electromagnetic signal transmission line in the middle and metal strips symmetrically distributed on both sides.

2. The millimeter-wave chip packaging structure with stripline transition as described in claim 1, characterized in that, The packaging structure also includes metal shielding pillars that run longitudinally through the dielectric layer of the entire horizontally suspended strip transition structure and are arranged at equal intervals along the non-radiative direction.

3. The millimeter-wave chip packaging structure with stripline transition as described in claim 1, characterized in that, The millimeter-wave chip packaging structure includes multiple redistribution layers, with a dielectric layer disposed between the multiple redistribution layers.

4. The millimeter-wave chip packaging structure with stripline transition as described in claim 1, characterized in that, The millimeter-wave chip packaging structure also includes a bottom metal layer, which is located in the redistribution layer, and a dielectric layer is disposed between the bottom metal layer and the redistribution layer.

5. The millimeter-wave chip packaging structure with stripline transition as described in claim 1, characterized in that, The stripline transition millimeter-wave chip packaging structure includes a single-channel stripline transition millimeter-wave chip packaging structure and a multi-channel stripline transition millimeter-wave chip packaging structure, corresponding to single and multiple horizontally suspended striplines, respectively. When multiple horizontally suspended strips are included, the multiple horizontally suspended strips have a symmetrical structure and are of equal length.

6. The millimeter-wave chip packaging structure with stripline transition as described in claim 5, characterized in that, The multi-channel stripline transition millimeter-wave chip packaging structure includes multiple antenna patches, which are symmetrically distributed about the millimeter-wave chip.

7. The millimeter-wave chip packaging structure with stripline transition as described in any one of claims 1 to 6, characterized in that, The dielectric layer is an LTCC dielectric layer.

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