Shielding structure and three-dimensional integrated microwave circuit

Abstract

The present application is applicable to the field of microwave circuit design technology, and provides a shielding structure and a three-dimensional integrated microwave circuit, including: a lower substrate, a lower substrate grounding pad, an upper substrate and an upper substrate grounding pad. The shielding grounding solder balls are arranged between the lower substrate grounding pad and the upper substrate grounding pad; the shielding grounding solder balls are arranged to form at least one closed figure, and the closed figure constitutes a shielding cavity. The shielding structure and three-dimensional integrated microwave circuit provided in the embodiment of the present application utilize the arrangement of shielding grounding solder balls to form a closed shielding cavity. By controlling the distance between adjacent shielding grounding solder balls constituting each shielding cavity, good electromagnetic wave shielding and isolation effects can be achieved. According to experiments, the shielding structure provided in the embodiment of the present application can achieve an isolation of more than 40dBc in the millimeter wave frequency band, effectively solving the problems of electromagnetic compatibility and electromagnetic interference in miniaturized three-dimensional circuits.

Description

Technical Field

[0001] The present application belongs to the field of microwave circuit design technology, and in particular relates to a shielding structure and a three-dimensional integrated microwave circuit. Background Art

[0002] With the increasing demand for miniaturization and high integration of microwave circuit products, three-dimensional integrated circuit technology has become an essential technical means and process approach. However, as circuit layout space becomes increasingly smaller and device distribution becomes increasingly compact, electromagnetic interference (EMI) has become a significant factor seriously restricting product performance. On the one hand, it is necessary to prevent devices from radiating electromagnetic waves externally, and on the other hand, to prevent external electromagnetic waves from interfering with internal devices. Electromagnetic shielding and isolation are particularly important in microwave and millimeter wave circuits. Summary of the Invention

[0003] In view of this, embodiments of the present application provide a shielding structure and a three-dimensional integrated microwave circuit to solve the problem of poor electromagnetic shielding effect in current microwave circuit design.

[0004] According to the first aspect, an embodiment of the present application provides a shielding structure, including a lower substrate, a lower substrate grounding pad arranged on the lower substrate, an upper substrate and an upper substrate grounding pad arranged on the upper substrate, the lower substrate grounding pad and the upper substrate grounding pad being arranged opposite to each other, characterized in that the shielding structure also includes: shielding grounding solder balls arranged between the lower substrate grounding pad and the upper substrate grounding pad; the shielding grounding solder balls are arranged to form at least one closed figure, and the closed figure constitutes a shielding cavity; the distance between adjacent shielding grounding solder balls arranged to form any closed figure is 2 to 2.5 times the height of the shielding grounding solder balls.

[0005] In combination with the first aspect, in some embodiments of the present application, the closed figure is a rectangle, a circle or an ellipse.

[0006] In combination with the first aspect, in some embodiments of the present application, the distance between adjacent shielding grounding solder balls arranged to form any closed figure is calculated by λ≥2a; wherein a is the distance between adjacent shielding grounding solder balls arranged to form any closed figure; λ is the wavelength of the electromagnetic wave that the shielding structure can shield.

[0007] In combination with the first aspect, in some embodiments of the present application, the shielding structure further includes: a grounding through hole provided in the lower substrate and / or the upper substrate.

[0008] According to a second aspect, an embodiment of the present application provides a three-dimensional integrated microwave circuit, which includes the shielding structure described in the first aspect or any embodiment of the first aspect.

[0009] In combination with the second aspect, in some embodiments of the present application, the three-dimensional integrated microwave circuit further includes a microwave circuit chip; and the microwave circuit chip is disposed in the shielding cavity of the shielding structure.

[0010] In combination with the second aspect, in some embodiments of the present application, the microwave circuit chip is mounted on a ground pad of the lower substrate of the shielding structure.

[0011] In combination with the second aspect, in some embodiments of the present application, internal substrate wires, internal signal ports and conductive blind holes are provided inside the lower substrate of the shielding structure; the microwave circuit chip is connected to the internal substrate wires through the internal signal ports and conductive blind holes.

[0012] In combination with the second aspect, in some embodiments of the present application, the microwave circuit chip is connected to the internal signal port via a bonding wire.

[0013] In combination with the second aspect, in some embodiments of the present application, an external signal port is provided on the lower substrate of the shielding structure; and the external signal port is connected to the internal wire of the substrate.

[0014] The shielding structure and three-dimensional integrated microwave circuit provided in the embodiments of this application utilize an arrangement of shielding ground solder balls to form a closed shielding cavity. By controlling the distance between adjacent shielding ground solder balls that form each shielding cavity, excellent electromagnetic wave shielding and isolation can be achieved. Tests have shown that the shielding structure provided in the embodiments of this application can achieve an isolation level exceeding 40dBc in the millimeter wave frequency band, effectively addressing electromagnetic compatibility and electromagnetic interference issues in miniaturized three-dimensional circuits. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments or descriptions of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0016] Figure 1 It is a schematic diagram of the waveguide principle;

[0017] Figure 2 It is a schematic diagram of the solder ball shielding principle;

[0018] Figure 3 is a structural diagram of a specific example of a shielding structure provided in an embodiment of the present application;

[0019] Figure 4 is a structural diagram of a specific example of a three-dimensional integrated microwave circuit provided in an embodiment of the present application;

[0020] Figure 5 yes Figure 4 Cross-sectional view of section AA'. DETAILED DESCRIPTION

[0021] In the following description, specific details such as specific system structures and techniques are provided for purposes of illustration rather than limitation to facilitate a thorough understanding of the embodiments of the present application. However, it will be apparent to those skilled in the art that the present application may be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to avoid obscuring the description of the present application with unnecessary detail.

[0022] Figure 1 This is a schematic diagram of the waveguide principle. Metal rectangular waveguides have high-pass filter properties. Commonly used metal rectangular waveguide dimensions are b = (0.4-0.5)a. When the wavelength λ (λ = c / f, where f is frequency and c is the speed of light) of the transmitted electromagnetic wave is λ ≥ 2a, electromagnetic waves of this wavelength will not propagate within the waveguide. Therefore, when λ ≥ 2a, i.e., when λ / 2 ≥ a, the frequency of this wavelength will not propagate within the rectangular waveguide. This means that electromagnetic waves with frequencies f and below will not propagate within the waveguide, and the waveguide exhibits high suppression and high isolation characteristics.

[0023] Figure 2 This is a schematic diagram of the solder ball shielding principle. Figure 2 In the example, if the distance between the two solder balls is a1, the height of the solder balls is b1, and the solder balls are grounded to the ground pads of the upper and lower substrates, the structure resembles a waveguide. When a1≈2b1 and λ1≥2a1, electromagnetic waves with frequencies f1 and below of wavelength λ1 will not pass through or enter the shielding structure, resulting in excellent internal and external isolation. By properly adjusting the dimensions of a1 and b1, very high-frequency isolation can be achieved. For example, using a 0.4mm diameter solder ball, a1=0.8mm, b1=0.4mm. Calculations show that, theoretically, electromagnetic waves with wavelengths greater than 1.6mm will not pass through the shielding structure, and the shielding frequency can reach over 100GHz.

[0024] The present embodiment utilizes the aforementioned solder ball shielding principle. In a three-dimensional circuit, the ground planes of the upper and lower substrates form upper and lower shielding layers. These layers are connected to the ground planes of the upper and lower substrates via a ball grid array (BGA), allowing the BGA solder balls to form shielding grounding solder balls, forming a side-shielding array structure. By controlling the spacing between the shielding grounding solder balls, a shielded cavity with excellent shielding effects on all sides can be formed, providing excellent shielding and isolation for the microwave system, circuits, or chips within.

[0025] In order to illustrate the technical solution described in this application, specific embodiments are provided below.

[0026] The embodiment of the present application provides a shielding structure, such as Figure 3 As shown, the shielding structure includes a lower substrate 2, a lower substrate grounding pad 5 provided on the lower substrate 2, an upper substrate 3, and an upper substrate grounding pad 6 provided on the upper substrate 3. The lower substrate grounding pad 5 is arranged opposite to the upper substrate grounding pad 6. In order to achieve the technical effect of electromagnetic shielding, a plurality of shielding grounding solder balls 1 can be provided in the shielding structure.

[0027] Specifically, the shielding ground solder balls 1 are all disposed between the lower substrate ground pad 5 and the upper substrate ground pad 6 , and the shielding ground solder balls 1 are in contact with the lower substrate ground pad 5 and the upper substrate ground pad 6 , respectively.

[0028] like Figure 3 As shown, a plurality of shielding grounding solder balls 1 are arranged to form at least one closed figure, and the closed figure constitutes a shielding cavity 4 .

[0029] exist Figure 3 In the figure, two shielding cavities 4 are schematically drawn. In practical applications, users can freely design the number of shielding cavities 4 according to their needs, and this embodiment of the application does not limit this. Figure 3 The shielding cavity 4 is rectangular in shape, which is only a schematic drawing. The user can also design the shielding cavity 4 into a circle, an ellipse or any other regular or irregular closed shape as needed.

[0030] In order to achieve good electromagnetic shielding and isolation effects similar to waveguide shielding, the distance between the shielding ground solder balls also needs to be limited.

[0031] Specifically, the distance between adjacent shielding grounding solder balls arranged to form any closed pattern may be set to 2 to 2.5 times the height of the shielding grounding solder balls.

[0032] In practical applications, users can calculate the distance between adjacent shielding grounding solder balls used to form any closed pattern according to the wavelength of the electromagnetic radiation to be shielded or isolated. Formula (1) gives the specific calculation formula:

[0033] λ≥2a (1)

[0034] Wherein, a is the distance between adjacent shielding grounding solder balls arranged to form any closed pattern; λ is the wavelength of electromagnetic waves that can be shielded by the shielding structure.

[0035] Optionally, a grounding through-hole 14 may be provided in the lower substrate 2 and / or the upper substrate 3. The shielding grounding solder ball 1 is connected to the lower substrate grounding pad 5 and the upper substrate grounding pad 6. Since the lower substrate grounding pad 5 and / or the upper substrate grounding pad 6 are connected to the grounding through-hole 14, the shielding grounding solder ball 1 has better grounding characteristics, thereby further improving the electromagnetic shielding and electromagnetic isolation energy efficiency of the shielding structure provided in the embodiment of the present application.

[0036] It should be noted that in Figure 3 The lower substrate ground pad 5, the upper substrate ground pad 6 and the ground through-hole 14 are not shown.

[0037] The embodiment of the present application also provides a three-dimensional integrated microwave circuit, such as Figure 4 and Figure 5 As shown, the three-dimensional integrated microwave circuit includes Figure 3 The shielding structure shown.

[0038] exist Figure 4 and Figure 5 In the three-dimensional integrated microwave circuit shown, the microwave circuit chip 7 is arranged in the shielding cavity 4 of the shielding structure.

[0039] Optionally, the microwave circuit chip 7 may be mounted on the lower substrate ground pad 5 of the shielding structure, or may be mounted on the upper substrate ground pad 6 of the shielding structure. Figure 4 and Figure 5 The following description is made schematically by taking the microwave circuit chip 7 mounted on the ground pad 5 of the lower substrate as an example.

[0040] like Figure 4 and Figure 5 As shown, when the microwave circuit chip 7 is mounted on the lower substrate ground pad 5 , an internal substrate wire 15 , an internal signal port 10 and a conductive blind via 13 may be provided inside the lower substrate 2 .

[0041] The microwave circuit chip 7 is connected to the internal conductor 15 of the substrate through the internal signal port 10 and the conductive blind via 13. In one embodiment, the microwave circuit chip 7 can be connected to the internal signal port 10 through a bonding wire 8.

[0042] Optionally, an external signal port 9 may be provided on the lower substrate 2 , and the external signal port 9 is connected to the internal conductor 15 of the substrate.

[0043] exist Figure 4 and Figure 5 In the three-dimensional integrated microwave circuit shown, a lower substrate grounding pad 5 and an upper substrate grounding pad 6 can be respectively provided between the upper layer of the lower substrate 2 and the lower layer of the upper substrate 3. The lower substrate grounding pad 5 is grounded via a grounding via 14.

[0044] The shielding ground solder ball 1 is connected to the lower substrate ground pad 5 and the upper substrate ground pad 6 . Since the pads are connected to the ground through-hole 14 , the shielding ground solder ball 1 has a good grounding characteristic.

[0045] By arranging the shielding grounding solder balls 1 in an array and reasonably distributing the distances between the shielding grounding solder balls 1 , a shielding cavity 4 having shielding characteristics can be formed by the plurality of shielding grounding solder balls 1 .

[0046] The microwave signal is input through the external signal port 9, connected to the internal substrate wire 15 through the conductive blind via 13, and then transmitted between the layers of the lower substrate 2. Then, it is connected to the internal signal port 10 through the conductive blind via 13, and then connected to the microwave circuit chip 7 through the bonding wire 8. The power supply can be connected to the microwave circuit chip 7 in sequence through the external feeding port 11, the conductive blind via 13, the internal substrate wire 15, the internal feeding port 12, and the bonding wire 8 for feeding.

[0047] The microwave signal is processed by microwave circuit chip 7 and then transmitted to the next microwave circuit chip 7 via bonding wires 8, internal signal port 10, conductive blind vias 13, and internal substrate conductors 15. Thanks to the shielding cavity 4, electromagnetic crosstalk and interference between two microwave circuit chips 7 are eliminated. Finally, the microwave signal is output through external signal port 9.

[0048] Similarly, when the microwave circuit chip 7 is mounted on the upper substrate ground pad 6, the Figure 4 and Figure 5 , circuits or interfaces such as substrate internal wires 15 , internal signal ports 10 and conductive blind vias 13 are arranged inside the upper substrate 3 .

[0049] The above-described embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present application, and should all be included in the scope of protection of the present application.

Claims

1. A shielding structure comprising a lower substrate, a lower substrate grounding pad disposed on the lower substrate, an upper substrate, and an upper substrate grounding pad disposed on the upper substrate, wherein the lower substrate grounding pad is disposed opposite to the upper substrate grounding pad, characterized in that: The shielding structure further includes: a shielding ground solder ball disposed between the lower substrate ground solder pad and the upper substrate ground solder pad; The shielding grounding solder balls are arranged to form at least one closed figure, and the closed figure constitutes a shielding cavity; The distance between adjacent shielding grounding solder balls arranged to form any closed pattern is 2 to 2.5 times the height of the shielding grounding solder balls; The distance between adjacent shielding grounding solder balls arranged to form any closed figure is calculated by λ≥2a; wherein a is the distance between adjacent shielding grounding solder balls arranged to form any closed figure; λ is the wavelength of the electromagnetic wave that the shielding structure can shield; the wavelength is the millimeter wave frequency band.

2. The shielding structure according to claim 1, wherein: The closed shape is a rectangle, a circle or an ellipse.

3. The shielding structure according to claim 1, wherein: The shielding structure further includes: a grounding through hole provided in the lower substrate and / or the upper substrate.

4. A three-dimensional integrated microwave circuit, characterized in that: The three-dimensional integrated microwave circuit includes the shielding structure according to any one of claims 1 to 3.

5. The three-dimensional integrated microwave circuit according to claim 4, wherein: The three-dimensional integrated microwave circuit further includes a microwave circuit chip; the microwave circuit chip is arranged in the shielding cavity of the shielding structure.

6. The three-dimensional integrated microwave circuit according to claim 5, characterized in that: The microwave circuit chip is mounted on the ground pad of the lower substrate of the shielding structure.

7. The three-dimensional integrated microwave circuit according to claim 6, wherein: The lower substrate of the shielding structure is provided with internal substrate wires, internal signal ports and conductive blind holes; The microwave circuit chip is connected to the internal wires of the substrate through the internal signal port and the conductive blind via.

8. The three-dimensional integrated microwave circuit according to claim 7, wherein: The microwave circuit chip is connected to the internal signal port via a bonding wire.

9. The three-dimensional integrated microwave circuit according to claim 8, wherein: An external signal port is provided on the lower substrate of the shielding structure; the external signal port is connected to the internal wire of the substrate.

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