An ultra-wideband high-performance radio frequency interconnection structure

Abstract

The application discloses a kind of ultra-wideband high-performance radio frequency interconnection structure, including laminated structure, radio frequency signal feed-in structure, first coaxial structure, strip line transmission structure, second coaxial structure, solder ball feed-out structure and ground via.The application is applied to ultra-wideband, through the design and key parameter optimization of coaxial structure and strip line transmission structure, so that radio frequency interconnection structure can be applied to DC~40GHz frequency band range;Gold wire bonding model is introduced, by increasing rectangular metal area in signal feed-in disc, to compensate the parasitic inductance effect introduced by bonding gold wire, improve the accuracy of simulation data.By configuring the key parameters of coaxial structure port and strip line port, the circuit design can be adjusted and adapted automatically by adjusting the number of metal layers and dielectric layers, as well as adjusting the length of strip line, reducing the circuit design time and complexity.The strip line transmission structure has no matching branch, reducing the processing difficulty.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of microwave package integrated circuits, and relates to a super-wideband high-performance radio frequency interconnection structure. BACKGROUND

[0002] In the design of high-frequency, high-integration, and miniaturized radio frequency microwave package integrated circuits, the transmission mode of microwave radio frequency signals is no longer limited to traditional planar microstrip line transmission and coaxial line transmission, and more signal interconnection transmission between different layers is needed, and the interconnection lines between radio frequency microstrip circuits, radio frequency microstrip circuits, and radio frequency chips greatly affect the radio frequency performance of the system. At present, in a phased array antenna system, the number of stacked layers of a ceramic substrate HTCC (High Temperature Co-Fired Ceramic) commonly used in a SIP (System in Package) microwave assembly has reached more than 20 layers. At this time, when radio frequency signals are transmitted and interconnected, discontinuity caused by impedance mismatch between a microstrip line-via-welding ball, a via-strip line-via, a microstrip line-via-strip line-via-microstrip line, and the like will occur, which will cause the standing wave ratio of the radio frequency signal to become larger, and at the same time, a large insertion loss will be introduced, and with the increase of the signal frequency, the phenomenon will be more obvious, which brings great inconvenience to the design of a Ka-band microwave circuit system. In order to avoid the deterioration of the radio frequency performance when microwave signals are transmitted across layers, it is extremely critical to research and design a super-wideband high-performance radio frequency interconnection structure.

[0003] The existing cross-layer transition radio frequency interconnection structure mostly adopts a strip line branch matching structure or sets a grounded conductive matching structure below a strip line conductive structure, as shown in Figure 1 and Figure 2 The above cross-layer transition radio frequency interconnection structures all have certain defects. The radio frequency interconnection structure using a strip line branch matching will increase a strip line matching branch. On the one hand, the increase of the matching branch will cause the available frequency band to become narrower, and when the frequency or the number of circuit layers changes, the size and position of the matching branch need to be determined through re-simulation, which increases the design time. On the other hand, the size of the matching branch is small, and the processing technology of the ceramic substrate is relatively high. If the size tolerance of the matching branch is slightly large, the frequency band will be shifted, the radio frequency performance index of the simulation cannot be achieved, and the actual engineering application cannot be met. The radio frequency interconnection structure using the grounded conductive matching structure below the strip line conductive structure will also have the same problems as the radio frequency interconnection structure using the strip line branch matching when the frequency or the number of circuit layers changes or due to the deviation of the processing size. Therefore, the above two cross-layer transition radio frequency interconnection structures do not have universality.

[0004] In microwave millimeter wave circuit applications, gold wire bonding process is needed for signal transmission and interconnection between radio frequency chips and radio frequency circuit structures, and the introduction of bonding gold wire will produce parasitic inductance effect. At present, most of the simulation of radio frequency switching structures does not consider the influence of bonding gold wire on the performance of radio frequency interconnection structure, thereby causing a large difference between the design simulation performance and the actual test performance, especially in Ka and Ka above frequency band. SUMMARY

[0005] In order to overcome the shortcomings of the prior art, the application provides a kind of ultra-wideband high-performance radio frequency interconnection structure.

[0006] In order to achieve the above purpose, the application adopts the following technical scheme:

[0007] An ultra-wideband high-performance radio frequency interconnection structure includes a laminated structure, a radio frequency signal feeding structure, a first coaxial structure, a strip line transmission structure, a second coaxial structure, a solder ball feeding structure and a ground via. The laminated structure includes a plurality of metal layers and dielectric layers, which are alternately and sequentially stacked. The opposite sides of the laminated structure along the stacking direction are respectively provided with a feeding metal layer for connecting with the radio frequency signal feeding structure and a feeding-out metal layer for connecting with the solder ball feeding structure. The strip line transmission structure is provided in the metal layer of the middle part of the laminated structure. The first coaxial structure and the second coaxial structure are respectively arranged on the opposite sides of the laminated structure along the stacking direction. The two ends of the strip line transmission structure are respectively connected with one end of the first coaxial structure and one end of the second coaxial structure. The other end of the first coaxial structure is connected with the radio frequency signal feeding structure, and the other end of the second coaxial structure is connected with the solder ball feeding structure. The ground via is provided through the laminated structure along the stacking direction.

[0008] Further, the strip line transmission structure includes a wiring metal layer, an avoidance metal layer and a reference ground metal layer. The middle part of the wiring metal layer is provided with a strip line, which is a 50-ohm strip line. The two ends of the strip line are respectively connected with the first coaxial structure and the second coaxial structure. The middle part of the wiring metal layer is hollowed out along the outer periphery of the strip line at a set interval to form a wiring hollowing-out area. The middle part of the avoidance metal layer is hollowed out to form an avoidance hollowing-out area. The outer periphery of the avoidance hollowing-out area coincides with the outer periphery of the wiring hollowing-out area in the projection along the stacking direction. The adjacent two sides of the wiring metal layer are provided with the avoidance metal layer. The adjacent outer sides of the two avoidance metal layers are provided with the reference ground metal layer.

[0009] Further, the ground via is distributed along the outer periphery of the wiring hollowing-out area.

[0010] Further, the first coaxial structure comprises a signal feed-in disc, a first signal hole and a first signal hole disc, the signal feed-in disc is arranged on the feed-in metal layer, a first avoiding interval is formed between the outer periphery of the signal feed-in disc and the feed-in metal layer, the first signal hole is arranged on the dielectric layer, the first signal hole disc is arranged on the metal layer, a second avoiding interval is formed between the first signal hole disc and the metal layer, the first signal hole is coaxially arranged with the signal feed-in disc and the first signal hole disc, and a plurality of grounding through holes are distributed along the circumference of the first signal hole, and a first center interval is formed between the center of the grounding through hole and the center of the first signal hole.

[0011] Further, the signal feed-in disc is a combination structure of a circle and a rectangle.

[0012] Further, the radio frequency signal feed-in structure comprises a first Port port, a microstrip transmission line, a substrate and a bonding gold wire, the first Port port and the microstrip transmission line are arranged on the substrate, the first Port port is connected with the microstrip transmission line, and the two ends of the bonding gold wire are respectively connected with the microstrip transmission line and the signal feed-in disc.

[0013] Further, the second coaxial structure comprises a signal feed-out disc, a second signal hole and a second signal hole disc, the signal feed-out disc is arranged on the feed-out metal layer, a third avoiding interval is formed between the outer periphery of the signal feed-out disc and the feed-out metal layer, the second signal hole is arranged on the dielectric layer, the first signal hole disc is arranged on the metal layer, a fourth avoiding interval is formed between the first signal hole disc and the metal layer, the second signal hole is coaxially arranged with the signal feed-out disc and the second signal hole disc, a plurality of grounding through holes are distributed along the circumference of the second signal hole, and a second center interval is formed between the center of the grounding through hole and the center of the second signal hole.

[0014] Further, the solder ball feed-out structure comprises a solder ball array and a second Port port, the second Port port is connected with the solder ball array, and the solder ball array is connected with the signal feed-out disc.

[0015] In summary, the present application has the advantages that:

[0016] The present application is applied to ultra-wideband, and through the design of coaxial structure and strip line transmission structure and the optimization of key parameters, the radio frequency interconnection structure can be applied to the frequency band range of DC-40GHz.

[0017] The golden wire bonding model is introduced, a rectangular metal area is added to the signal feed-in disc to compensate the parasitic inductance effect introduced by the bonding golden wire, and the accuracy of the simulation data is improved.

[0018] By configuring the key parameters of the coaxial structure port and the strip line port, the circuit design can be adjusted by the number of metal layers and dielectric layers and the length of the strip line, so as to adaptively adjust and reduce the circuit design time and complexity.

[0019] The strip line transmission structure has no matching branch, and the processing difficulty is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 It is a strip line branch matching structure in the prior art.

[0021] Figure 2 It is a conductive matching structure provided below the strip line conductive structure in the prior art.

[0022] Figure 3 It is a structure diagram of the radio frequency interconnection structure.

[0023] Figure 4 It is a structure diagram of the laminated structure.

[0024] Figure 5 It is a schematic diagram of each layer plane of the strip line transmission structure.

[0025] Figure 6 It is a schematic diagram of the wire metal layer plane.

[0026] Figure 7 It is a schematic diagram of the signal feed-in disc of the first coaxial structure.

[0027] Figure 8 It is a schematic diagram of the signal feed-out disc of the second coaxial structure.

[0028] Figure 9 It is a data diagram of the return loss in the simulation test.

[0029] Figure 10 It is a data diagram of the insertion loss in the simulation test.

[0030] Figure 11 It is a rectangular array solder ball feed-out structure diagram.

[0031] Figure 12 It is a circular array solder ball feed-out structure diagram. DETAILED DESCRIPTION

[0032] Following make the present application's implementation mode through specific concrete example, the person skilled in the art can easily understand the other advantages and efficacy of the present application from the disclosure of the present specification.The present application can also be implemented or applied by another different specific implementation, and the details in the present specification can be based on different views and applications, various modifications or changes are made without departing from the spirit of the present application.It should be noted that the following examples and features in the examples can be combined with each other without conflict.

[0033] It should be noted that the drawings provided in the following examples only illustrate the basic concept of the present application in a schematic manner, and only the components related to the present application are shown in the drawings, not drawn according to the number, shape and size of the components in actual implementation, the type, number and proportion of each component in actual implementation can be changed arbitrarily, and the component layout type can be more complex.

[0034] All directional indications (such as up, down, left, right, front, back, transverse, longitudinal...) in the embodiments of the present application are only used to explain the relative position relationship, motion condition and the like between the components in a certain specific posture, and if the specific posture changes, the directional indications will also change accordingly.

[0035] Due to installation errors and other reasons, the parallel relationship referred to in the embodiments of the present application may actually be an approximate parallel relationship, and the vertical relationship may actually be an approximate vertical relationship.

[0036] The present application provides a kind of ultra-wideband high-performance radio frequency interconnection structure, referring to Figure 3 Including dielectric layer, metal layer, radio frequency signal feed-in structure, first coaxial structure, strip line transmission structure, second coaxial structure, solder ball feed-out structure, radio frequency signal is vertically transmitted from top to bottom, radio frequency signal is input by feed-in structure, after first coaxial structure, strip line transmission structure, second coaxial structure, it is exported by solder ball.

[0037] The radio frequency signal feed-in structure includes a first Port port, a microstrip transmission line, a GaAs substrate, and a gold wire, wherein the impedance of the first Port port is 50 ohms, the microstrip transmission line is a 50 ohm standard microstrip line with a line width of 70 microns, the substrate material is GaAs, the gold wire has a diameter of 25 microns and a length of 300 microns, and the gold wire has an arch height of 60 microns. The radio frequency signal is fed in from the first Port port, transmitted to the gold wire through the microstrip transmission line, simulates the actual application scenario of the radio frequency circuit, simulates the parasitic inductance effect introduced by the gold wire bonding, and improves the accuracy of the simulation data.

[0038] The first coaxial structure includes a signal feed-in disc, a first signal hole, a first signal hole disc, and a ground through hole. Referring to Figure 7As shown, the signal feed-in disc is a combination of a circular shape with a diameter of 0.3 mm and a rectangular shape with a size of 0.2*0.16 mm, and the rectangular part is used to compensate for the parasitic inductance effect introduced by the bonding wire, thereby improving the accuracy of the simulation data. The clearance distance d1 between the signal feed-in disc and the surrounding metal is 0.1 mm. The center distance d3 between the first signal hole and the ground through hole on the outer periphery thereof is 0.65 mm, the first signal hole disc diameter Φ1 is 0.18 mm, and the clearance distance d4 between the first signal hole disc and the metal layer is 0.45 mm.

[0039] The second coaxial structure includes a second signal hole, a second signal hole disc, a ground through hole, and a signal feed-out disc. As shown in Figure 8 As shown, the diameter of the signal feed-out disc is the same as the diameter of the solder ball used, which is 0.4 mm, the metal clearance distance d2 of the signal feed-out disc is 0.15 mm, the center distance d3 between the second signal hole and the ground through hole on the outer periphery thereof is 0.65 mm, the second signal hole disc diameter Φ1 is 0.18 mm, and the clearance distance d4 between the second signal hole disc and the metal layer is 0.45 mm.

[0040] The solder ball feed-out structure includes a solder ball array and a second Port port, wherein the second Port port impedance is 50 ohms, the solder ball material is set to Sn10Pb90, and the solder ball array includes but is not limited to a rectangular array or a circular array, as shown in Figure 11 and Figure 12 As shown, preferably in this embodiment, the solder ball diameter Φ2 is 0.4 mm, and the solder ball is a 3*3 rectangular array, including a total of 9 solder balls.

[0041] The dielectric layers and the metal layers are sequentially stacked in the vertical direction to form a laminated structure, as shown in Figure 4 As shown, the top and bottom of the laminated structure are both set as metal layers, and the inside is a sequential arrangement of metal layers and dielectric layers, so that the upper and lower two sides of the internal dielectric layer are both metal layers, and the upper and lower two sides of the metal layer are also both dielectric layers, so that in the laminated structure, the number of dielectric layers is M, and the number of metal layers is N=M+1. In this embodiment, the dielectric layer is set to at least four layers, and the metal layer is set to at least five layers. As a preferred scheme, the dielectric layer is set to 10 layers, and the metal layer is set to 11 layers.

[0042] The material of the dielectric layer is alumina, and the thickness of a single dielectric layer is preferably 0.15 mm.

[0043] The material of the metal layer is copper, and the thickness of a single metal layer is preferably 10 microns.

[0044] As shown in Figure 5 .

[0045] When the metal layer is set as a wiring metal layer, as shown inFigure 6 The middle part of the trace metal layer is provided with a strip line, the strip line is a standard 50-ohm strip line, the line width is 0.14 mm, the line length L is preferably 2.4 mm, the metal within the set distance is hollowed out along the outer periphery of the strip line, so that in the trace metal layer, the strip line and the surrounding metal form a spacing with an avoidance distance d5 = 0.25 mm, the center of the left and right ends of the strip line is provided through, which is used for respectively communicating with the first signal hole and the second signal hole, the outer periphery of the left and right ends of the strip line is also hollowed out along the set distance to form a circular spacing with an avoidance distance d4 = 0.45 mm, and all the hollowed-out spacings are communicated to form a hollowed-out area along the circumferential direction of the strip line.

[0046] The ground vias are arranged in the same pose on each metal layer and each dielectric layer, the ground vias are distributed along the outer periphery of the hollowed-out area on the trace metal layer in the circumferential direction, and the projections of the ground vias of each layer on the entire laminated structure coincide in the vertical direction.

[0047] When the metal layer is set as an avoidance metal layer, the middle part of the avoidance metal layer is hollowed out, and the hollowed-out area coincides with the hollowed-out area of the trace metal layer in the vertical projection direction, the first signal hole disc and the second signal hole disc are respectively arranged at the left and right ends of the hollowed-out area of the avoidance metal layer and respectively coincide with the left and right ends of the strip line in the vertical projection direction, and the centers of the first signal hole disc and the second signal hole disc are throughly arranged.

[0048] When the metal layer is set as a reference ground metal layer, a ground via is arranged on the reference ground metal layer.

[0049] In the distribution arrangement of the metal layers in the embodiment, the trace metal layer is taken as the center, the metal layers on the upper and lower sides adjacent to the trace metal layer are respectively set as two avoidance metal layers, the upper side metal layer of the upper avoidance metal layer is set as a reference ground metal layer, and the lower side metal layer of the lower avoidance metal layer is set as a reference ground metal layer, so as to finally form the strip line transmission structure.

[0050] The first signal hole and the second signal hole are both arranged on the dielectric layer, and in the distribution arrangement of the laminated structure, the first signal hole communicates with one end of the first signal hole disc and the strip line in the vertical projection direction, and the second signal hole communicates with the other end of the second signal hole disc and the strip line in the vertical projection direction.

[0051] Further, in the embodiment, the radio frequency interconnection structure is simulated and tested in the range of DC-40 GHz, a back-to-back structure is arranged, and through actual test verification by a probe station, in the range of DC-40 GHz, the measured result of the structure has an insertion loss less than 1 dB and a return loss better than -15 dB. The comparison chart of simulation and measurement data is referred to Figure 9 、 Figure 10The structure can be applied to radio frequency interconnection in the range of 0-40GHz, the model has high accuracy and strong universality, the processing difficulty and design complexity are reduced, and the performance deterioration problem of high-frequency radio frequency vertical interconnection structure is solved.

[0052] The back-to-back structure is connected and arranged in a symmetrical distribution by two groups of radio frequency interconnection structures.

[0053] Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor shall belong to the protection scope of the present application.

Claims

1. An ultra-wideband high performance radio frequency interconnect structure, characterized by, The application relates to a coaxial structure, a radio frequency signal feeding structure, a first coaxial structure, a strip line transmission structure, a second coaxial structure, a solder ball feeding structure and a grounding through hole.

2. The ultra wide band high performance radio frequency interconnection structure of claim 1, wherein, The first coaxial structure comprises a signal feeding disc, a first signal hole and a first signal hole disc, the signal feeding disc is arranged on the feeding metal layer, a first avoiding interval is formed between the outer periphery of the signal feeding disc and the feeding metal layer, the first signal hole is arranged on the dielectric layer, the first signal hole disc is arranged on the metal layer, a second avoiding interval is formed between the first signal hole disc and the metal layer, the first signal hole is coaxially arranged in communication with the signal feeding disc and the first signal hole disc, a plurality of the grounding through holes are distributed along the circumferential direction of the first signal hole, and the center of the grounding through hole is spaced apart from the center of the first signal hole to form a first center interval.

3. The ultra wide band high performance RF interconnection structure of claim 2, wherein, The signal feeding disc is a combined structure of a circle and a rectangle.

4. The ultra-wideband high performance RF interconnection structure of claim 2 or 3, wherein, The radio frequency signal feeding structure comprises a first Port port, a microstrip transmission line, a substrate, and a bonding gold wire. The first Port port and the microstrip transmission line are arranged on the substrate, the first Port port is connected with the microstrip transmission line, and two ends of the bonding gold wire are respectively connected with the microstrip transmission line and the signal feeding disc. The microstrip transmission line is a 50-ohm standard microstrip line.

5. The ultra wide band high performance RF interconnection structure of claim 1, wherein, The second coaxial structure comprises a signal feeding disc, a second signal hole, and a second signal hole disc. The signal feeding disc is arranged on the feeding metal layer. A third avoiding interval is formed between the outer periphery of the signal feeding disc and the feeding metal layer. The second signal hole is arranged in the dielectric layer. The second signal hole disc is arranged on the metal layer. A fourth avoiding interval is formed between the second signal hole disc and the metal layer. The second signal hole is coaxially and communicatively arranged with the signal feeding disc and the second signal hole disc. A plurality of grounding through holes are distributed along the circumference of the second signal hole. A second center interval is formed between the center of the grounding through hole and the center of the second signal hole.

6. The ultra wide band high performance RF interconnection structure of claim 5, wherein, The solder ball feeding structure comprises a solder ball array and a second Port port. The second Port port is connected with the solder ball array. The solder ball array is connected with the signal feeding disc.

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