Interconnection structure of BGA (Ball Grid Array) packaging chip and PCB (Printed Circuit Board) and terminal

Abstract

The invention provides an interconnection structure of a BGA packaging chip and a PCB and a terminal, the BGA packaging chip comprises a chip grounding reference plane and a solder ball group, and the solder ball group comprises signal solder balls and grounding solder balls; the PCB comprises a first metal layer, a second metal layer and a third metal layer; according to the invention, the signal transmission line is arranged in the hollowed-out area of the second metal layer, so that a backflow signal of the grounding solder ball can be transmitted through the signal transmission line in the hollowed-out area, a signal backflow path is shortened, most of the backflow signal is propagated from the second metal layer, and spanning of the backflow signal between the second metal layer and the third metal layer is reduced; according to the PCB, the resonance problem caused by an electromagnetic wave parallel plate mode is weakened, high-bandwidth data transmission can be realized, the structure of the third metal layer is not influenced, and a more compact high-speed PCB design can be realized.

Description

Technical Field

[0001] The present invention relates to the technical field of optical communications, and in particular to an interconnection structure and a terminal of a BGA packaged chip and a PCB board. Background Art

[0002] In recent years, the rapid development of 5G communications, cloud computing, and artificial intelligence has placed higher demands on the transmission speed of network facilities. As a core component in optical communications and data centers, the transmission speed of optical modules has gradually evolved from the initial 100G to 400G, 800G, and even 1.6T. In optical modules, the interconnection between the signals of each device is a major factor affecting the transmission rate. In particular, the core electronic chips responsible for processing high-speed signals within the optical module are generally packaged using BGA packaging. The continuous increase in transmission speed has placed higher requirements on the bandwidth of the interconnection structure between the BGA packaged chip and the PCB board. Specifically, in related technologies, the return signal of the interconnection structure between the BGA packaged chip and the PCB board diffuses over a large area on the second and third metal layers of the PCB board, causing strong resonance, which in turn affects the bandwidth of the interconnection structure between the BGA packaged chip and the PCB board. Summary of the Invention

[0003] In view of the above problems, the present invention provides an interconnection structure and a terminal for a BGA packaged chip and a PCB board for realizing high-bandwidth data transmission.

[0004] According to a first aspect of the present invention, there is provided an interconnection structure between a BGA packaged chip and a PCB board, wherein the BGA packaged chip includes a chip ground reference plane and a solder ball group located on one side of the chip ground reference plane, the solder ball group including signal solder balls and ground solder balls; the PCB board includes a first metal layer, a second metal layer and a third metal layer, the first metal layer includes an anti-pad area and a ground area, the orthographic projection of the signal solder ball on the first metal layer is located in the anti-pad area, the orthographic projection of the ground solder ball on the first metal layer is located in the ground area, and a differential transmission line is provided in the anti-pad area; the second metal layer is located on a side of the first metal layer away from the BGA packaged chip, the second metal layer includes a hollow area corresponding to the anti-pad area, and a signal transmission line is provided in the hollow area; the third metal layer is located on a side of the second metal layer away from the first metal layer; wherein the signal solder ball is electrically connected to the differential transmission line, and the ground solder ball is electrically connected to the signal transmission line.

[0005] According to an embodiment of the present invention, in the top view direction of the interconnection structure between the BGA packaged chip and the PCB board, the ground solder ball is located in the direction of the signal solder ball away from the differential transmission line; at least one of the ground solder balls arranged close to the signal solder ball is connected to the area close to the differential transmission line on the second metal layer through the signal transmission line.

[0006] According to an embodiment of the present invention, the PCB board further includes a first dielectric layer and a second dielectric layer, the first dielectric layer is located between the first metal layer and the second metal layer, and the second dielectric layer is located between the second metal layer and the third metal layer; wherein a plurality of first conductive vias are provided on the first dielectric layer, the first conductive vias connecting the first metal layer and the second metal layer, and the grounding solder balls are electrically connected to the signal transmission lines through the first conductive vias; and no vias are provided on the second dielectric layer.

[0007] According to an embodiment of the present invention, a plurality of second conductive vias are further provided on the first dielectric layer, the second conductive vias connecting the first metal layer and the second metal layer, and the orthographic projections of the plurality of second conductive vias on the first metal layer are located on both sides of the differential transmission line.

[0008] According to an embodiment of the present invention, at least two circular pads are provided in the anti-pad area, and the two microstrip lines in the differential transmission line are electrically connected to the signal solder balls through the corresponding circular pads, respectively.

[0009] According to an embodiment of the present invention, the spacing between two adjacent circular pads is greater than the spacing between two adjacent microstrip lines; wherein the microstrip line includes an arc segment and a straight segment, and the arc segment connects the circular pad and the straight segment.

[0010] According to an embodiment of the present invention, in an extension direction parallel to the first metal layer and perpendicular to the microstrip line, the width of the arc segment is greater than the width of the straight segment.

[0011] According to an embodiment of the present invention, the orthographic projection of the signal transmission line on the first metal layer does not overlap with the circular pad.

[0012] According to an embodiment of the present invention, in a top view direction of the interconnection structure between the BGA packaged chip and the PCB board, the shape of the area in the anti-pad area corresponding to the hollowed-out area is rectangular.

[0013] According to a second aspect of the present invention, a terminal is provided, comprising the above-mentioned interconnection structure between the BGA packaged chip and the PCB board.

[0014] Beneficial effects of the present invention: The present invention provides an interconnection structure between a BGA packaged chip and a PCB board, wherein the BGA packaged chip includes a chip ground reference plane and a solder ball group located on one side of the chip ground reference plane, wherein the solder ball group includes a signal solder ball and a ground solder ball; the PCB board includes a first metal layer, a second metal layer, and a third metal layer, wherein the first metal layer includes an anti-pad area and a ground area, wherein the orthographic projection of the signal solder ball on the first metal layer is located in the anti-pad area, wherein the orthographic projection of the ground solder ball on the first metal layer is located in the ground area, and wherein a differential transmission line is provided in the anti-pad area; wherein the second metal layer is located on a side of the first metal layer away from the BGA packaged chip, wherein the second metal layer includes a hollow area corresponding to the anti-pad area, wherein the hollow area A signal transmission line is provided; the third metal layer is located on a side of the second metal layer away from the first metal layer; wherein the signal solder ball is electrically connected to the differential transmission line, and the ground solder ball is electrically connected to the signal transmission line; the embodiment of the present invention sets a signal transmission line in a hollow area of ​​the second metal layer, so that the reflow signal of the ground solder ball can be transmitted through the signal transmission line in the hollow area, shortening the signal reflow path, so that most of the reflow signal is transmitted from the second metal layer, reducing the reflow signal crossing between the second metal layer and the third metal layer, weakening the resonance problem caused by the parallel plate mode of the electromagnetic wave, and realizing high-bandwidth data transmission without affecting the structure of the third metal layer, thereby realizing a more compact high-speed PCB design. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The above contents and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

[0016] Figure 1 A schematic perspective view of the interconnection structure between a BGA packaged chip and a PCB board according to an embodiment of the present invention is shown;

[0017] Figure 2 A schematic top view of the interconnection structure between a BGA packaged chip and a PCB board according to an embodiment of the present invention is shown;

[0018] Figure 3 A side view schematically shows an interconnection structure between a BGA packaged chip and a PCB board according to an embodiment of the present invention;

[0019] Figure 4 Schematically shows a top view of a first metal layer according to an embodiment of the present invention;

[0020] Figure 5 Schematically shows a top view of a second metal layer according to an embodiment of the present invention;

[0021] Figure 6 Schematically shows a top view of a third metal layer according to an embodiment of the present invention;

[0022] Figure 7 Schematically shows a top view of a second metal layer according to a reference comparative example;

[0023] Figure 8 A graph schematically showing how the reflection coefficient of an embodiment of the present invention and a reference comparative example vary with frequency; and

[0024] Figure 9 The graph schematically shows the transmission coefficient of the embodiment of the present invention and the reference comparative example changing with frequency. DETAILED DESCRIPTION

[0025] To make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to specific embodiments and the accompanying drawings. It is apparent that the embodiments described are only a portion of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are intended to fall within the scope of protection of the present invention.

[0026] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. The terms "comprise", "include", etc. used herein indicate the presence of the features, steps, operations and / or components, but do not exclude the presence or addition of one or more other features, steps, operations or components.

[0027] In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they may refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or mutual communication; direct connection or indirect connection through an intermediate medium; internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0028] In the description of the present invention, it should be understood that the terms "longitudinal", "length", "circumferential", "front", "rear", "left", "right", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the subsystem or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0029] Throughout the drawings, identical elements are represented by identical or similar reference numerals. Conventional structures or configurations may be omitted where they may obscure the understanding of the present invention. Furthermore, the shapes, sizes, and positional relationships of the components in the drawings do not reflect actual size, proportion, or actual positional relationships. Furthermore, any reference symbols between parentheses in the present invention should not be construed as limiting the present invention.

[0030] Similarly, in order to streamline the present invention and aid in understanding one or more of the various disclosed aspects, in the above description of exemplary embodiments of the present invention, the various features of the present invention are sometimes grouped together into a single embodiment, figure, or description thereof. Descriptions with reference to the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples" and the like mean that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0031] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the technical features being referred to. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means at least two, such as two or three, unless otherwise specifically defined.

[0032] The following, combined Figures 1 to 6 The interconnection structure between the BGA packaged chip and the PCB board provided by the embodiment of the present invention is introduced in detail, wherein: Figure 1 A schematic perspective view of the interconnection structure between a BGA packaged chip and a PCB board according to an embodiment of the present invention is shown. Figure 2 A schematic top view of the interconnection structure between a BGA packaged chip and a PCB board according to an embodiment of the present invention is shown. Figure 3 A side view schematically shows the interconnection structure between a BGA packaged chip and a PCB board according to an embodiment of the present invention. Figure 4 Schematically shows a top view of the first metal layer according to an embodiment of the present invention, Figure 5 Schematically shows a top view of the second metal layer according to an embodiment of the present invention, Figure 6 FIG. 1 schematically shows a top view of a third metal layer according to an embodiment of the present invention.

[0033] In this embodiment, the BGA packaged chip includes a chip ground reference plane 10 and a solder ball group 11 located on one side of the chip ground reference plane 10, wherein the solder ball group 11 includes a signal solder ball 111 and a ground solder ball 112; the PCB board includes a first metal layer 20, a second metal layer 30, and a third metal layer 40, wherein the first metal layer 20 includes an anti-pad area A1 and a ground area A2, and the orthographic projection of the signal solder ball 111 on the first metal layer 20 is located in the anti-pad area A1, and the orthographic projection of the ground solder ball 112 on the first metal layer 20 is located in the anti-pad area A1. Located in the grounding area A2, a differential transmission line 21 is set in the anti-pad area A1; the second metal layer 30 is located on the side of the first metal layer 20 away from the BGA package chip, and the second metal layer 30 includes a hollow area A3 corresponding to the anti-pad area A1, and a signal transmission line 31 is set in the hollow area A3; the third metal layer 40 is located on the side of the second metal layer 30 away from the first metal layer 20; wherein the signal solder ball 111 is electrically connected to the differential transmission line 21, and the grounding solder ball 112 is electrically connected to the signal transmission line 31.

[0034] It should be noted that the BGA packaged chip refers to an electronic chip packaged using a ball grid array (BGA). The chip ground reference plane 10 corresponds to the bottom surface of the electronic chip. The solder ball group 11 is used to connect to the PCB board to achieve signal interconnection. The two signal solder balls 111 are electrically connected to the two microstrip lines 211 in the differential transmission line 21, respectively, to transmit the signal of the differential transmission line 21 to the BGA packaged chip. The at least one ground solder ball 112 surrounding the signal solder balls 111 then transmits the reflow signal to the area of ​​the second metal layer 30 of the PCB board near the differential transmission line 21.

[0035] It should be noted that, in the related art, the hollowing area A30 of the second metal layer 300 is completely hollowed out (e.g. Figure 7 ).like Figure 5 As shown, the second metal layer 30 in this embodiment is not completely hollowed out, but some metal lines are retained as signal transmission lines 31, that is, the hollowed-out area A3 in this embodiment is a metal mesh hollow (the width of the metal mesh hollow structure needs to be adjusted through simulation and testing to achieve the best transmission effect), and the reflow signal of the ground solder ball 112 is transmitted to the area near the differential transmission line 21 in the second metal layer 30 through the signal transmission line 31 to shorten the reflow path. Specifically, if the signal transmission line 31 is not set, the reflow signal will be conducted from the periphery of the hollowed-out area A3 (needs to turn); in this embodiment, the reflow signal is conducted through the signal transmission line 31, which can be conducted in a straight line, so the path is shorter. It should be noted that the second metal layer 30 and the third metal layer 40 in this embodiment are reference ground layers.

[0036] It can be understood that the embodiment of the present invention sets a signal transmission line 31 in the hollow area A3 of the second metal layer 30, so that the reflow signal of the grounding solder ball 112 can be transmitted through the signal transmission line 31 in the hollow area A3, shortening the signal reflow path, so that most of the reflow signal is transmitted from the second metal layer 30, reducing the reflow signal crossing between the second metal layer 30 and the third metal layer 40, weakening the resonance problem caused by the parallel plate mode of the electromagnetic wave, and realizing high-bandwidth data transmission. It is suitable for application scenarios of multi-channel parallel transmission and will not affect the structure of the third metal layer 40. Other routing arrangements can be made on the third metal layer 40 to achieve a more compact high-speed PCB design.

[0037] In some embodiments, the surface of the PCB is covered with a green oil layer 50 , and the area of ​​the green oil layer 50 corresponding to the solder ball group 11 is exposed, so as to facilitate the interconnection between the BGA packaged chip and the PCB.

[0038] In some embodiments, in the top view direction of the interconnection structure between the BGA package chip and the PCB board, as shown in FIG. Figure 2 The ground solder ball 112 is located in the direction of the signal solder ball 111 away from the differential transmission line 21; at least one of the ground solder balls 112 arranged near the signal solder ball 111 is connected to the area near the differential transmission line 21 on the second metal layer 30 through the signal transmission line 31.

[0039] It should be noted that Figure 2 In the figure, the solder ball group 11 is illustrated as including two signal solder balls 111 and six ground solder balls 112, but the present invention is not limited thereto. Figure 2 In the figure, two signal solder balls 111 are electrically connected to two microstrip lines 211 in the differential transmission line 21, respectively. Six other ground solder balls 112 are evenly arranged in the direction from the signal solder balls 111 away from the differential transmission line 21. The signal transmission line 31 connects the four ground solder balls 112 closest to the signal solder balls 111 at the shortest distance. Two other ground solder balls 112 are further away from the signal solder balls 111, resulting in poor transmission performance and therefore not being used as a path for the reflow signal. The signal transmission line 31 forms the shortest path between the reference ground plane directly below the differential transmission line 21 (i.e., the area on the second metal layer 30 near the differential transmission line 21) and the four ground solder balls 112 closest to the signal solder balls 111. This path is used to conduct the displacement current of the reflow signal electromagnetic wave, thereby shortening the signal reflow path to a certain extent.

[0040] In some embodiments, as Figure 3As shown, the PCB board also includes a first dielectric layer 60 and a second dielectric layer 70, the first dielectric layer 60 is located between the first metal layer 20 and the second metal layer 30, and the second dielectric layer 70 is located between the second metal layer 30 and the third metal layer 40; wherein, a plurality of first conductive vias 601 are provided on the first dielectric layer 60, the first conductive vias 601 connecting the first metal layer 20 and the second metal layer 30, and the grounding solder balls 112 are electrically connected to the signal transmission lines 31 through the first conductive vias 601; no vias are provided on the second dielectric layer 70.

[0041] It will be appreciated that in this embodiment, multiple first conductive vias 601 are provided on the first dielectric layer 60 to achieve connectivity between the first metal layer 20 and the second metal layer 30. The ground solder ball 112 first contacts the grounding area A2 of the first metal layer 20. The reflow signal is then transmitted to the signal transmission line 31 of the second metal layer 30 through the first conductive vias 601 between the first metal layer 20 and the second metal layer 30. The first conductive vias 601 are, for example, inner wall plated vias. Specifically, the first conductive vias 601 are located directly below the ground solder balls 112.

[0042] It is understandable that in this embodiment, no vias are provided between the second metal layer 30 and the third metal layer 40, so that the layout and wiring of the third metal layer 40 in the PCB board will not be affected. Therefore, other routing arrangements can be made on the third metal layer 40, which can achieve a more compact high-speed PCB design. Figure 6 As shown, the third metal layer 40 is a complete metal plane without vias.

[0043] In some embodiments, the first dielectric layer 60 is further provided with a plurality of second conductive vias 602. The second conductive vias 602 connect the first metal layer 20 and the second metal layer 30. The orthographic projections of the plurality of second conductive vias 602 on the first metal layer 20 are located on both sides of the differential transmission line 21. It will be appreciated that, by providing the plurality of second conductive vias 602 on both sides of the differential transmission line 21, this embodiment can reduce the resonance of the microstrip line 211, thereby reducing its impact on signal transmission. The second conductive vias 602 are, for example, inner wall metallized vias.

[0044] In some embodiments, as Figure 4 As shown, at least two circular pads 22 are provided in the anti-pad area A1 , and the two microstrip lines 211 in the differential transmission line 21 are electrically connected to the signal solder balls 111 through the corresponding circular pads 22 .

[0045] In some embodiments, as Figure 4As shown, the spacing between two adjacent circular pads 22 is greater than the spacing between two adjacent microstrip lines 211 ; wherein the microstrip line 211 includes an arc segment 2111 and a straight segment 2112 , and the arc segment 2111 connects the circular pad 22 and the straight segment 2112 .

[0046] It can be understood that since the spacing between the two microstrip lines 211 in the differential transmission line 21 is slightly smaller than the spacing between two adjacent circular pads 22, this embodiment divides the microstrip line 211 into an arc segment 2111 and a straight segment 2112, and the arc segment 2111 is used for the transition of smaller spacing.

[0047] In some embodiments, as Figure 4 As shown, in the extension direction parallel to the first metal layer 20 and perpendicular to the microstrip line 211, the width of the arc segment 2111 is greater than the width of the straight segment 2112. It can be understood that this embodiment appropriately widens the arc segment 2111 to reduce the impedance of the arc segment 2111, thereby compensating for the impedance increase caused by the reduced coupling between the differential pairs.

[0048] In some embodiments, the orthographic projection of the signal transmission line 31 on the first metal layer 20 does not overlap with the circular pad 22. It will be appreciated that in related art, the entire hollowed-out area A30 of the second metal layer 300 is hollowed out, so that the reference ground plane for the signal solder ball is the third metal layer. Since the distance between the signal solder ball and the third metal layer is greater than the distance between the signal solder ball and the second metal layer, this has an impedance-enhancing effect. In this embodiment, by ensuring that the orthographic projection of the signal transmission line 31 on the first metal layer 20 does not overlap with the circular pad 22, the reference ground plane for the signal solder ball 111 of this embodiment is also the third metal layer 40. Therefore, this embodiment can maintain an impedance-enhancing effect similar to that achieved by completely hollowing out the entire area, thereby facilitating reductions in return loss and insertion loss.

[0049] In some embodiments, in the top view direction of the interconnection structure between the BGA package chip and the PCB board, the shape of the area in the anti-pad area A1 corresponding to the hollow area A3 is rectangular. Figure 5 As shown, the hollowed area A3 is in the shape of a rectangle, and some metal wires are retained in the rectangle. Figure 4 As shown, the anti-pad area A1 refers to the portion separating the ground area A2 and the differential transmission line 21. It will be appreciated that, in this embodiment, by making the area corresponding to the anti-pad area A1 and the hollowed-out area A3 rectangular, the area can be as large as possible without affecting the surrounding first conductive vias 601, thereby maximizing the compensation for the impedance reduction caused by the large soldering area between the signal solder ball 111 and the round pad 22.

[0050] In order to further illustrate the beneficial effects of the present invention, a reference comparative example is taken for comparison with the embodiment of the present invention. Figures 7 to 9 , Figure 7 is a top view of the second metal layer 300 according to the reference comparative example, Figure 8 is a graph showing how the reflection coefficient of the embodiment of the present invention and the reference example vary with frequency, Figure 9 Graph showing transmission coefficients versus frequency for the embodiment of the present invention and the reference comparative example, wherein the hollowed-out area A30 of the second metal layer 300 of the reference comparative example is completely hollowed out, and the rest remains the same as that of the embodiment of the present invention.

[0051] refer to Figure 8 、 Figure 9 As shown, the reflection coefficient and transmission coefficient of the embodiment of the present invention are compared with the reference comparative example. It can be seen that the transmission characteristics of the two are basically the same, but the curve of the embodiment of the present invention is smoother, and the transmission loss in the frequency band above 50 GHz is lower, which proves that the embodiment of the present invention has better transmission performance for high-frequency signals than the reference comparative example.

[0052] The embodiment of the present invention further provides a terminal, including the interconnection structure of the BGA package chip and the PCB board. The terminal is, for example, an optical module. For a detailed description of the interconnection structure of the BGA package chip and the PCB board, please refer to Figures 1 to 6 And related descriptions are not repeated here.

[0053] The above describes embodiments of the present invention. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention. Although each embodiment has been described separately above, this does not mean that the measures in each embodiment cannot be advantageously used in combination. The scope of the present invention is defined by the appended claims and their equivalents. Without departing from the scope of the present invention, those skilled in the art may make various substitutions and modifications, which should all fall within the scope of the present invention.

Claims

1. A BGA packaged chip and PCB board interconnection structure, characterized in that: The BGA packaged chip includes a chip ground reference plane and a solder ball group located on one side of the chip ground reference plane, wherein the solder ball group includes signal solder balls and ground solder balls; The PCB board includes: a first metal layer comprising an anti-pad region and a ground region, wherein an orthographic projection of the signal solder ball on the first metal layer is located within the anti-pad region, an orthographic projection of the ground solder ball on the first metal layer is located within the ground region, and a differential transmission line is disposed within the anti-pad region; a second metal layer, located on a side of the first metal layer away from the BGA package chip, the second metal layer comprising a hollow area corresponding to the anti-pad area, wherein a signal transmission line is provided in the hollow area; a third metal layer, located on a side of the second metal layer away from the first metal layer; The signal solder ball is electrically connected to the differential transmission line, and the ground solder ball is electrically connected to the signal transmission line.

2. The interconnection structure of the BGA packaged chip and the PCB board according to claim 1, characterized in that: In the top view direction of the interconnection structure between the BGA packaged chip and the PCB board, the ground solder ball is located in the direction of the signal solder ball away from the differential transmission line; at least one of the ground solder balls arranged close to the signal solder ball is connected to the area close to the differential transmission line on the second metal layer through the signal transmission line.

3. The interconnection structure of the BGA packaged chip and the PCB board according to claim 1, characterized in that: The PCB board further includes a first dielectric layer and a second dielectric layer, the first dielectric layer is located between the first metal layer and the second metal layer, and the second dielectric layer is located between the second metal layer and the third metal layer; Among them, a plurality of first conductive vias are provided on the first dielectric layer, the first conductive vias connect the first metal layer and the second metal layer, and the grounding solder ball is electrically connected to the signal transmission line through the first conductive vias; no vias are provided on the second dielectric layer.

4. The interconnection structure of the BGA packaged chip and the PCB board according to claim 3, characterized in that: A plurality of second conductive vias are further provided on the first dielectric layer. The second conductive vias connect the first metal layer and the second metal layer. The orthographic projections of the plurality of second conductive vias on the first metal layer are located on both sides of the differential transmission line.

5. The interconnection structure of the BGA packaged chip and the PCB board according to claim 1, characterized in that: At least two circular pads are provided in the anti-pad area, and the two microstrip lines in the differential transmission line are electrically connected to the signal solder balls through the corresponding circular pads respectively.

6. The interconnection structure of the BGA packaged chip and the PCB board according to claim 5, characterized in that: The distance between two adjacent circular pads is greater than the distance between two adjacent microstrip lines; The microstrip line includes an arc segment and a straight segment, and the arc segment connects the circular pad and the straight segment.

7. The interconnection structure of the BGA packaged chip and the PCB board according to claim 6, characterized in that: In an extension direction parallel to the first metal layer and perpendicular to the microstrip line, the width of the arc segment is greater than the width of the straight segment.

8. The interconnection structure of the BGA packaged chip and the PCB board according to claim 5, characterized in that: The orthographic projection of the signal transmission line on the first metal layer does not overlap with the circular pad.

9. The interconnection structure of the BGA packaged chip and the PCB board according to claim 1, characterized in that: In the top view direction of the interconnection structure between the BGA packaged chip and the PCB board, the shape of the area in the anti-pad area corresponding to the hollowed-out area is rectangular.

10. A terminal, characterized in that: The invention comprises an interconnection structure between a BGA packaged chip and a PCB board according to any one of claims 1 to 9.

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