Ultra-wideband high-performance radio frequency interconnection structure

Abstract

The invention discloses an ultra-wideband high-performance radio frequency interconnection structure which comprises a laminated structure, a radio frequency signal feed-in structure, a first similar coaxial structure, a strip line transmission structure, a second similar coaxial structure, a solder ball feed-out structure and a grounding through hole. According to the ultra-wideband radio frequency interconnection structure, ultra-wideband application is adopted, and the radio frequency interconnection structure can be applied to a DC-40GHz frequency band range through the design of a quasi-coaxial structure and a strip line transmission structure and key parameter optimization; a gold wire bonding model is introduced, and a rectangular metal area is additionally arranged on a signal feed-in disc to compensate a parasitic inductance effect introduced by a gold bonding wire, so that the accuracy of simulation data is improved. By configuring key parameters of the port of the quasi-coaxial structure and the port of the strip line, self-adaptive adjustment and adaptation can be realized by adjusting the number of layers of the metal layers and the dielectric layers and adjusting the length of the strip line during circuit design, so that the circuit design time is shortened, and the circuit design complexity is reduced. And the strip line transmission structure has no matching branch knot, so that the processing difficulty is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of microwave packaging integrated circuits, and relates to an ultra-wideband high-performance radio frequency interconnection structure. Background Art

[0002] In the design of high-frequency, high-integration, and miniaturized radio frequency and microwave packaging integrated circuits, the transmission mode of microwave radio frequency signals is no longer limited to traditional planar microstrip line transmission and coaxial line transmission. More signal interconnection transmissions between different layers are required, and the interconnection traces between radio frequency microstrip circuits, radio frequency microstrip circuits and radio frequency chips have a great impact on the radio frequency performance of the system. Currently, in a phased array antenna system, the number of stacked layers of the commonly used ceramic substrate HTCC (High Temperature Co-Fired Ceramic) of SiP (System in Package) microwave components has reached more than 20 layers. At this time, discontinuities caused by impedance mismatches will occur during radio frequency signal transmission interconnection, such as between microstrip line-via-bump, via-strip line-via, microstrip line-via-strip line-via-microstrip line, etc. This will cause the standing wave ratio of the radio frequency signal to increase, and at the same time, a large insertion loss will be introduced. Moreover, as the signal frequency increases, the phenomenon will become more obvious, which brings great inconvenience to the design of microwave circuit systems in the Ka band. In order to avoid the deterioration of radio frequency performance when microwave signals are transmitted across layers, it is extremely crucial to research and design an ultra-wideband high-performance radio frequency interconnection structure.

[0003] Existing cross-layer transition radio frequency interconnection structures mostly adopt strip line stub matching structures or conductive matching structures grounded under the strip line conductive structure, specifically as Figure 1 and Figure 2 shown. All of the above cross-layer transition radio frequency interconnection structures have certain defects. Adopting a strip line stub matching radio frequency interconnection structure will increase the strip line matching stubs. The increase of this matching stub will, on the one hand, cause the available frequency band to become narrower, and when the frequency or the number of circuit stacked layers changes, re-simulation is required to determine the size and position of the matching stub, increasing the design time. On the other hand, the size of the matching stub is small, and the processing technology requirements for the ceramic substrate are high. If the dimensional tolerance of the matching stub is slightly larger, the frequency band will shift, and the radio frequency performance indicators of the simulation cannot be achieved, and it cannot meet the application of actual engineering; the radio frequency interconnection structure with a conductive matching structure grounded under the strip line conductive structure will also have the same problems as the strip line stub matching radio frequency interconnection structure due to changes in frequency or the number of circuit stacked layers or due to processing size deviations. Therefore, the above two cross-layer transition radio frequency interconnection structures are not universal.

[0004] In microwave and millimeter wave circuit applications, the signal transmission interconnection between the RF chip and the RF circuit structure requires the use of a gold wire bonding process. The introduction of bonding gold wire will produce a parasitic inductance effect. Currently, most RF switching structures do not consider the impact of bonding gold wire on the performance of the RF interconnection structure during simulation, resulting in a large difference between the design simulation performance and the actual testability, especially in the Ka and above frequency bands. Summary of the invention

[0005] In order to overcome the deficiencies of the prior art, the present invention provides an ultra-wideband high-performance radio frequency interconnect structure.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] An ultra-wideband high-performance radio frequency interconnection structure comprises a laminated structure, a radio frequency signal feeding structure, a first type of coaxial structure, a stripline transmission structure, a second type of coaxial structure, a solder ball feeding structure and a grounding through hole, wherein the laminated structure comprises a plurality of metal layers and dielectric layers, wherein the metal layers and the dielectric layers are alternately stacked in sequence; opposite sides along a stacking direction of the laminated structure are respectively arranged as a feeding metal layer for connecting to the radio frequency signal feeding structure and a feeding metal layer for connecting to the solder ball feeding structure; the stripline transmission structure is arranged on the metal layer in the middle of the laminated structure, the first type of coaxial structure and the second type of coaxial structure are respectively arranged on opposite sides of the laminated structure along the stacking direction, two ends of the stripline transmission structure are respectively connected to one end of the first type of coaxial structure and one end of the second type of coaxial structure, the other end of the first type of coaxial structure is connected to the radio frequency signal feeding structure, and the other end of the second type of coaxial structure is connected to the solder ball feeding structure; the grounding through hole is arranged through the laminated structure along the stacking direction.

[0008] Furthermore, the stripline transmission structure includes a routing metal layer, an avoidance metal layer and a reference ground metal layer, a stripline is arranged in the middle of the routing metal layer, the stripline is a 50 ohm stripline, and the two ends of the stripline are respectively connected to the first type coaxial structure and the second type coaxial structure, the middle of the routing metal layer is hollowed out along the periphery of the stripline at a set interval to form a routing hollowing area, the middle of the avoidance metal layer is hollowed out to form an avoidance hollowing area, the periphery of the avoidance hollowing area coincides with the periphery of the routing hollowing area under the projection in the stacking direction, the adjacent two sides of the routing metal layer are set as the avoidance metal layers, and the adjacent outer sides of the two avoidance metal layers are set as the reference ground metal layers.

[0009] Furthermore, the grounding vias are distributed along the periphery of the routing hollowed-out area.

[0010] Furthermore, the first type of coaxial structure includes a signal feeding disk, a first signal hole, and a first signal hole disk. The signal feeding disk is disposed on the feeding metal layer, and a first avoidance distance is formed by the interval between the outer periphery of the signal feeding disk and the feeding metal layer. The first signal hole penetrates through the dielectric layer, and the first signal hole disk is disposed on the metal layer. A second avoidance distance is formed by the interval between the first signal hole disk and the metal layer. The first signal hole is coaxially connected to the signal feeding disk and the first signal hole disk. A plurality of the grounding through holes are distributed along the circumference of the first signal hole, and a first center distance is formed by the interval between the center of the grounding through hole and the center of the first signal hole.

[0011] Furthermore, the signal feeding disk has a combined structure of a circle and a rectangle.

[0012] Furthermore, the radio frequency signal feeding structure includes a first Port port, a microstrip transmission line, a substrate, and a bonding wire. The first Port port and the microstrip transmission line are disposed on the substrate. The first Port port is connected to the microstrip transmission line. Two ends of the bonding wire are respectively connected to the microstrip transmission line and the signal feeding disk. The microstrip transmission line is a 50-ohm standard microstrip line.

[0013] Furthermore, the second type of coaxial structure includes a signal output disk, a second signal hole, and a second signal hole disk. The signal output disk is disposed on the output metal layer, and a third avoidance distance is formed by the interval between the outer periphery of the signal output disk and the output metal layer. The second signal hole penetrates through the dielectric layer, and the first signal hole disk is disposed on the metal layer. A fourth avoidance distance is formed by the interval between the first signal hole disk and the metal layer. The second signal hole is coaxially connected to the signal output disk and the second signal hole disk. A plurality of the grounding through holes are distributed along the circumference of the second signal hole, and a second center distance is formed by the interval between the center of the grounding through hole and the center of the second signal hole.

[0014] Furthermore, the solder ball output structure includes a solder ball array and a second Port port. The second Port port is connected to the solder ball array, and the solder ball array is connected to the signal output disk.

[0015] In summary, the advantages of the present invention are as follows:

[0016] The present invention adopts ultra-wideband applications. Through the design of a coaxial-like structure and a stripline transmission structure and the optimization of key parameters, the radio frequency interconnection structure can be applied in the frequency band range of DC to 40 GHz;

[0017] A gold wire bonding model is introduced. By adding a rectangular metal area to the signal feeding disk, the parasitic inductance effect introduced by the bonding gold wire is compensated, and the accuracy of the simulation data is improved.

[0018] By configuring the key parameters of the quasi-coaxial structure port and the strip line port, during circuit design, it can be adaptively adjusted and matched by adjusting the number of metal layers and dielectric layers, as well as the length of the strip line, reducing the circuit design time and complexity.

[0019] The strip line transmission structure has no matching stub, reducing the processing difficulty. Brief Description of the Drawings

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

[0021] Figure 2 It is the conductive matching structure with grounding arranged below the strip line conductive structure in the prior art.

[0022] Figure 3 It is the schematic structural diagram of the radio frequency interconnection structure of the present invention.

[0023] Figure 4 It is the schematic structural diagram of the stacked structure.

[0024] Figure 5 It is the schematic plan view of each layer of the strip line transmission structure.

[0025] Figure 6 It is the schematic plan view of the trace metal layer.

[0026] Figure 7 It is the schematic plan view of the signal feeding disk of the first type of coaxial structure.

[0027] Figure 8 It is the schematic plan view of the signal output disk of the second type of coaxial structure.

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

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

[0030] Figure 11 It is the structure diagram of the rectangular array solder ball output.

[0031] Figure 12 It is the structure diagram of the circular array solder ball output. Detailed Embodiment

[0032] The following describes the embodiments of the present invention through specific examples. Those skilled in the art can easily understand the other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0033] It should be noted that the diagrams provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner. Therefore, only the components related to the present invention are shown in the diagrams, rather than being drawn according to the number, shape, and size of the components in actual implementation. The type, quantity, and ratio of each component in actual implementation can be arbitrarily changed, and the component layout type may also be more complex.

[0034] All directional indications (such as up, down, left, right, front, back, horizontal, vertical...) in the embodiments of the present invention are only used to explain the relative position relationship and movement conditions between components in a specific posture. If the specific posture changes, the directional indications will also change accordingly.

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

[0036] The present invention provides an ultra-wideband high-performance radio frequency interconnection structure. Referring to Figure 3 , it includes a dielectric layer, a metal layer, a radio frequency signal feeding structure, a first type of coaxial structure, a stripline transmission structure, a second type of coaxial structure, and a solder ball feeding structure. When the radio frequency signal is vertically transmitted from top to bottom, the radio frequency signal is input by the feeding structure, and after passing through the first type of coaxial structure, the stripline transmission structure, and the second type of coaxial structure, it is output at the solder ball.

[0037] The radio frequency signal feeding structure includes a first Port port, a microstrip transmission line, a GaAs substrate, and a bonding wire. Among them, 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 set as GaAs, the diameter of the gold wire is 25 microns, the length is 300 microns, and the arch height of the gold wire is 60 microns. The radio frequency signal is fed into the first Port port and transmitted to the bonding wire through the microstrip transmission line, simulating the actual application scenario of the radio frequency circuit and simulating the parasitic inductance effect introduced by gold wire bonding to improve the accuracy of the simulation data.

[0038] The first type of coaxial structure includes a signal feeding disk, a first signal hole, a first signal hole disk, and a grounding via. Among them, referring to Figure 7As shown, the signal feeding disk is a combination of a circle with a diameter of 0.3 mm and a rectangle of 0.2×0.16 mm. The rectangular part is used to compensate for the parasitic inductance effect introduced by the bonding wire and improve the accuracy of the simulation data. The clearance distance d1 between the signal feeding disk and the surrounding metal is 0.1 mm. The center distance d3 between the first signal hole and the grounding through hole on its outer periphery is 0.65 mm. The diameter Φ1 of the first signal hole disk is 0.18 mm. The clearance distance d4 between the first signal hole disk and the metal layer is 0.45 mm.

[0039] The second type of coaxial structure includes a second signal hole, a second signal hole disk, a grounding through hole, and a signal output disk. Among them, referring to Figure 8 As shown, the diameter of the signal output disk is the same as the diameter of the solder ball used, which is 0.4 mm. The metal clearance distance d2 of the signal output disk is 0.15 mm. The center distance d3 between the second signal hole and the grounding through hole on its outer periphery is 0.65 mm. The diameter Φ1 of the second signal hole disk is 0.18 mm. The clearance distance d4 between the second signal hole disk and the metal layer is 0.45 mm.

[0040] The solder ball output structure includes a solder ball array and a second Port port. Among them, the impedance of the second Port port is 50 ohms. The solder ball material is set to Sn10Pb90. The solder ball array includes, but is not limited to, a rectangular array or a circular array. Referring to Figure 11 and Figure 12 As shown, in this embodiment, preferably, the solder ball diameter Φ2 is 0.4 mm, and the solder balls are arranged in a 3×3 rectangular array, with a total of 9 solder balls.

[0041] The dielectric layer and the metal layer are stacked in sequence in the vertical direction to form a stacked structure. Referring to Figure 4 As shown, both the top and bottom of the stacked structure are set as metal layers, and the inside is an alternating arrangement of metal layers and dielectric layers, so that both the upper and lower adjacent sides of the internal dielectric layers are metal layers, and both the upper and lower adjacent sides of the metal layers are also dielectric layers. Thus, in the stacked 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 at least set to four layers, and the metal layer is at least set to five layers. As a preferred solution, 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 μm.

[0044] Among them, the metal layer can be set as a routing metal layer, or a clearance metal layer, or a reference ground metal layer. Referring to Figure 5 As shown.

[0045] When the metal layer is set as a routing metal layer, referring toFigure 6 , a strip line is arranged in the middle of the wiring metal layer. The strip line is a standard 50-ohm strip line with a line width of 0.14 mm. The line length L is preferably 2.4 mm. The metal within a set spacing is hollowed out along the outer periphery of the strip line, so that within the wiring metal layer, an interval with an avoidance spacing of d5 = 0.25 mm is formed between the strip line and the surrounding metal. The centers of the left and right ends of the strip line are arranged in a through manner for communicating with the first signal hole and the second signal hole respectively. The outer peripheries of the left and right ends of the strip line are also hollowed out along the set spacing to form a circular interval with an avoidance spacing of d4 = 0.45 mm. All the hollowed-out intervals are circumferentially communicated along the circumference of the strip line to form a hollowed-out area.

[0046] Ground vias are arranged on each metal layer and each dielectric layer with the same pose distribution. The ground vias are distributed circumferentially along the outer periphery of the hollowed-out area on the wiring metal layer, and the projections of the ground vias on each layer of the entire stacked structure coincide in the vertical direction.

[0047] When the metal layer is set as the avoidance metal layer, the middle of the avoidance metal layer is hollowed out, and the hollowed-out area coincides with the hollowed-out area of the wiring metal layer in the vertical projection direction. The first signal hole pad and the second signal hole pad are respectively arranged at the left and right ends of the hollowed-out area of the avoidance metal layer, and coincide with the left and right ends of the strip line respectively in the vertical projection direction. The centers of the first signal hole pad and the second signal hole pad are both arranged in a through manner.

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

[0049] In the distribution setting of the metal layers in this embodiment, with the wiring metal layer as the center, the metal layers on the upper and lower adjacent sides of the wiring metal layer are respectively set as two avoidance metal layers. The upper metal layer of the upper avoidance metal layer is set as the reference ground metal layer, and the lower metal layer of the lower avoidance metal layer is set as the reference ground metal layer to finally form the strip line transmission structure.

[0050] Both the first signal hole and the second signal hole are arranged on the dielectric layer. Under the distribution setting of the stacked structure, the first signal hole is communicated with one end of the first signal hole pad and the strip line in the vertical projection direction, and the second signal hole is communicated with the other end of the second signal hole pad and the strip line in the vertical projection direction.

[0051] Furthermore, in this embodiment, the radio frequency interconnection structure is simulated and tested in the range of DC~40 GHz, and is arranged in a back-to-back structure. After actual test verification by a probe station, in the range of DC~40 GHz, the measured insertion loss of this structure is less than 1 dB, and the return loss is better than -15 dB. The comparison chart of simulation and measured data is referred to Figure 9 、 Figure 10As shown. It can be concluded that this structure can be applied to radio frequency interconnection in the range of 0 - 40 GHz, with high model accuracy, strong versatility, reduced processing difficulty, design complexity, and solves the problem of performance deterioration of radio frequency vertical interconnection structures in the high frequency band.

[0052] Among them, the back-to-back structure is arranged by connecting two sets of radio frequency interconnection structures in a symmetric distribution.

[0053] Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

Claims

1. An ultra-wideband high-performance radio frequency interconnect structure, characterized in that: The invention comprises a stacked structure, a radio frequency signal feeding structure, a first type of coaxial structure, a stripline transmission structure, a second type of coaxial structure, a solder ball feeding structure and a grounding through hole. The stacked structure comprises a plurality of metal layers and dielectric layers, and the metal layers and the dielectric layers are alternately stacked in sequence. Two opposite sides of the stacked structure along the stacking direction are respectively arranged as a feeding metal layer for connecting with the radio frequency signal feeding structure and a feeding metal layer for connecting with the solder ball feeding structure. The stripline transmission structure is arranged on the metal layer in the middle of the stacked structure. The first type of coaxial structure and the second type of coaxial structure are respectively arranged on the opposite sides of the stacked structure along the stacking direction. Two ends of the stripline transmission structure are respectively connected to one end of the first type of coaxial structure and one end of the second type of coaxial structure, the other end of the first type of coaxial structure is connected to the radio frequency signal feeding structure, and the other end of the second type of coaxial structure is connected to the solder ball feeding structure. The grounding through hole is arranged through the stacked structure along the stacking direction.

2. The ultra-wideband high-performance radio frequency interconnect structure according to claim 1, characterized in that: The stripline transmission structure includes a routing metal layer, an avoidance metal layer and a reference ground metal layer. A stripline is arranged in the middle of the routing metal layer, and the stripline is a 50-ohm stripline. Both ends of the stripline are respectively connected to the first type coaxial structure and the second type coaxial structure. The middle of the routing metal layer is hollowed out along the periphery of the stripline at a set interval to form a routing hollowing area. The middle of the avoidance metal layer is hollowed out to form an avoidance hollowing area. The periphery of the avoidance hollowing area coincides with the periphery of the routing hollowing area in the projection in the stacking direction. The adjacent two sides of the routing metal layer are set as the avoidance metal layers, and the adjacent outer sides of the two avoidance metal layers are set as the reference ground metal layers.

3. The ultra-wideband high-performance radio frequency interconnect structure according to claim 2, characterized in that: The grounding vias are distributed along the periphery of the routing hollowing area.

4. The ultra-wideband high-performance radio frequency interconnect structure according to claim 1, characterized in that: The first type of coaxial structure includes a signal feeding disk, a first signal hole and a first signal hole disk, the signal feeding disk is arranged on the feeding metal layer, the outer periphery of the signal feeding disk and the feeding metal layer are spaced to form a first avoidance distance, the first signal hole is penetrated through the dielectric layer, the first signal hole disk is arranged on the metal layer, the first signal hole disk and the metal layer are spaced to form a second avoidance distance, the first signal hole is coaxially connected with the signal feeding disk and the first signal hole disk, a plurality of the grounding through holes are distributed along the circumference of the first signal hole, and the center of the grounding through hole and the center of the first signal hole are spaced to form a first center distance.

5. The ultra-wideband high-performance radio frequency interconnect structure according to claim 4, characterized in that: The signal feeding disk is a combined structure of a circle and a rectangle.

6. An ultra-wideband high-performance radio frequency interconnect structure according to claim 4 or 5, characterized in that: The RF signal feeding structure includes a first Port, a microstrip transmission line, a substrate, and a bonding gold wire. The first Port and the microstrip transmission line are arranged on the substrate. The first Port is connected to the microstrip transmission line. Both ends of the bonding gold wire are respectively connected to the microstrip transmission line and the signal feeding disk. The microstrip transmission line is a 50-ohm standard microstrip line.

7. The ultra-wideband high-performance radio frequency interconnect structure according to claim 1, characterized in that: The second type of coaxial structure includes a signal feed plate, a second signal hole, and a second signal hole plate. The signal feed plate is arranged on the feed metal layer, and the outer periphery of the signal feed plate and the feed metal layer are spaced to form a third avoidance distance. The second signal hole is penetrated through the dielectric layer, and the first signal hole plate is arranged on the metal layer. The first signal hole plate and the metal layer are spaced to form a fourth avoidance distance. The second signal hole is coaxially connected with the signal feed plate and the second signal hole plate. A plurality of grounding through holes are distributed along the circumference of the second signal hole, and the center of the grounding through hole and the center of the second signal hole are spaced to form a second center distance.

8. The ultra-wideband high-performance radio frequency interconnect structure according to claim 7, characterized in that: The solder ball feed-out structure includes a solder ball array and a second Port port, the second Port port is connected to the solder ball array, and the solder ball array is connected to the signal feed-out pad.

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