Radio frequency signal transmission structure

Abstract

The utility model discloses a radio frequency signal transmission structure, and relates to the technical field of radio frequency interconnection, the structure comprises a coaxial connector, a PCB mother board, a BGA vertical transition structure, an HTCC substrate and an organic composite substrate, the BGA vertical transition structure, the HTCC substrate and the organic composite substrate are sequentially connected, the BGA vertical transition structure, the HTCC substrate and the organic composite substrate are sequentially overlapped above the PCB mother board, and the HTCC substrate is connected with the coaxial connector. The PCB mother board, the BGA vertical transition structure and the HTCC substrate are sequentially connected through radio frequency bonding pads which are arranged respectively, based on the mature HTCC technology, the signal transmission structure of ultra-wideband radio frequency signals with good transmission performance is achieved within the frequency band of 0.1 GHz-20 GHz, the loss of the structure within the frequency band does not exceed 0.6 dB, and the ultra-wideband radio frequency signal transmission structure has the excellent electrical characteristics of ultra-wide working frequency band, ultra-low insertion loss and the like. And meanwhile, the signal transmission structure is high in integration level and small in processing difficulty, is adaptive to an automatic production line, and can meet the requirements of SIP microwave components.

Description

Technical Field

[0001] The utility model relates to the technical field of radio frequency interconnection, and more specifically, to a radio frequency signal transmission structure. Background Art

[0002] As microwave components continue to develop towards miniaturization, the RF signal transmission method in traditional microwave components is difficult to meet the development needs. In order to achieve miniaturization, how to ensure RF performance in the three-dimensional integration of vertical interconnection structures has become a hot research direction in the industry.

[0003] High temperature co-fired ceramics (HTCC) mainly use tungsten metal as a conductor material and co-fire it with ceramic materials such as alumina at around 1600°C, and use processes such as brazing and plating to complete the shell processing technology of connecting parts of different materials and surface treatment; HTCC has the advantages of high integration and good thermal conductivity; BGA (Ball Grid Array) packaging has the advantages of high interconnection density and good interconnection RF signal integrity, so HTCC and BGA are gradually being widely used in vertical interconnection structures.

[0004] The SIP structure is used on the PCB motherboard through soldering of the pads at the bottom, and HTCC is widely used as the substrate material of SIP. In order to achieve efficient automated assembly, the internal circuit of SIP usually uses an organic composite substrate as a signal transmission medium; currently, the vertical transition structure of PCB motherboard-SIP is mostly focused on modeling and simulation between the same substrate, and there is little research on the transmission performance of the complete transmission path between SIP and traditional PCB boards. How to achieve the signal transmission integrity of SIP-BGA-PCB based on the current process level is the key to the problem. Utility Model Content

[0005] The purpose of the utility model is to provide a radio frequency signal transmission structure, which realizes a signal transmission structure of an ultra-wideband radio frequency signal with good transmission performance in the frequency band of 0.1GHz to 20GHz based on mature HTCC process technology. The loss of the structure in the frequency band does not exceed 0.6dB, and it has excellent electrical characteristics such as ultra-wide working frequency band and ultra-low insertion loss. At the same time, the signal transmission structure has high integration, low processing difficulty, and is suitable for automated production lines, which can meet the needs of SIP microwave components.

[0006] The above technical objectives of the utility model are achieved through the following technical solutions:

[0007] The present application provides a radio frequency signal transmission structure, comprising a coaxial connector, a PCB motherboard, a BGA vertical transition structure, a HTCC substrate and an organic composite substrate connected in sequence, wherein:

[0008] The BGA vertical transition structure, the HTCC substrate and the organic composite substrate are sequentially overlapped on top of the PCB motherboard. The PCB motherboard, the BGA vertical transition structure and the HTCC substrate are sequentially connected through respectively arranged radio frequency pads. The BGA vertical transition structure is also provided with array solder balls, and the radio frequency pads of the BGA vertical transition structure are located in the middle of the array solder balls.

[0009] On the basis of the above technical solution, the present invention can also be improved as follows.

[0010] Furthermore, the coaxial connector and the PCB motherboard are connected via a microstrip line and a stripline that are interconnected, the microstrip line is connected to the output end of the coaxial connector, and the stripline is connected to the input end of the PCB motherboard.

[0011] Furthermore, the radio frequency pad of the HTCC substrate is connected to the input end of the organic composite substrate through a gold wire.

[0012] Furthermore, the dielectric models of the above-mentioned microstrip lines and strip lines are both TSM-DS3M, where:

[0013] The number of dielectric layers of the microstrip line is 1, the number of dielectric layers of the stripline is 2, and the thickness of the single-layer dielectric of the microstrip line and the stripline is 0.254 mm.

[0014] Furthermore, the conduction strip width of the above-mentioned microstrip line is 0.62 mm.

[0015] Furthermore, the conductive strip width of the strip line is 0.3 mm.

[0016] Furthermore, the PCB motherboard comprises a first substrate, a second substrate and a third substrate which are overlapped in sequence, wherein:

[0017] The first substrate, the second substrate and the third substrate are respectively penetrated by a plurality of metal through holes whose positions correspond to each other; the second substrate is provided with a transition structure, the upper end surface of the third substrate is provided with a radio frequency pad of the PCB motherboard, and the transition structure is connected to the radio frequency pad of the PCB motherboard, and the upper end surface of the third substrate is also provided with a connecting pad corresponding to the array solder ball of the BGA vertical transition structure.

[0018] Furthermore, the above-mentioned BGA vertical transition structure includes a fourth substrate, a fifth substrate, a sixth substrate, a seventh substrate, an eighth substrate and a ninth substrate which are overlapped in sequence, wherein:

[0019] The array solder balls are arranged on the fourth substrate, the fifth substrate and the sixth substrate are penetrated by metal through holes corresponding to those in the PCB motherboard, the seventh substrate, the eighth substrate and the ninth substrate are also provided with first through holes around the RF pads; the upper end surface of the ninth substrate is provided with a RF pad of a BGA vertical transition structure.

[0020] Furthermore, the organic composite substrate comprises a tenth substrate, an eleventh substrate and a twelfth substrate stacked in sequence, wherein:

[0021] The tenth substrate and the eleventh substrate are both penetrated by a plurality of evenly distributed second through holes, the upper end surface of the twelfth substrate is provided with a microstrip transmission line, and the RF pad of the HTCC substrate is connected to one end of the microstrip transmission line through a gold wire.

[0022] Furthermore, in the above-mentioned PCB motherboard, BGA vertical transition structure and organic composite substrate, the thickness of each layer of the substrate is 0.1 mm.

[0023] Compared with the prior art, the present invention has at least the following beneficial effects:

[0024] In the present application, the operating frequency band of the RF signal transmission structure is 0.1GHz to 20GHz, and the maximum insertion loss within the frequency band is 0.6dB. It has excellent electrical characteristics such as wide operating frequency band and low insertion loss. The input and output port impedances are both 50 ohms, which meets the universal design requirements. It is very suitable for miniaturized SIP microwave components that interconnect multiple substrates with wider operating bandwidth and lower noise requirements.

[0025] In the present application, the RF signal transmission structure fully considers the current mainstream HTCC, organic composite substrate and BGA process levels in the design layout. All dimensional parameters in the structure can meet the normal processing capabilities of HTCC and BGA. It has low processing difficulty and high integration, meets the needs of automated assembly, fully complies with the universal design requirements between multiple substrates, and is very suitable for mass production.

[0026] In the present application, the RF signal of the broadband RF BGA vertical transition structure first transitions to the microstrip line and the stripline through the coaxial insulator of the SMP, vertically transitions to the BGA array through the PCB motherboard, and vertically transitions from the BGA array to the SIP substrate HTCC, and then is transmitted to the organic composite substrate output through gold wire bonding; metal shielding through holes are arranged around the transmission path to constrain the electromagnetic signal, and the transmission structure parameters can be appropriately changed and optimized to be applicable to HTCC and organic composite substrate substrate circuits with different numbers of layers and different parameters, and the derivability is strong; the stripline medium is TSM-DS3M, and the single-layer thickness is 0.254mm; the number of dielectric layers is 2, and the microstrip line medium is TSM-DS3M, and the single-layer thickness is 0.254mm; the number of dielectric layers is 1. Both microstrip and stripline use 50Ω standard lines, of which the conduction width of the microstrip line is 0.62mm; the conduction width of the stripline is 0.3mm; other conditions such as dielectric loss and metal thickness simulate the actual situation (metal thickness 18um, dielectric loss 0.002). The SIP includes an HTCC substrate shell and an organic composite substrate; the HTCC single layer thickness is 0.1mm; the number of dielectric layers is 5. The organic composite substrate medium is M6, with a single layer thickness of 0.1mm; the number of dielectric layers is 3. The BGA array in this structure can meet different BGA packaging forms, improving the interchangeability and versatility of SIP products. The BGA vertical transition structure in the RF signal transmission structure is suitable for the vertical transition of BGA between different substrates, expanding the use scenarios of the traditional BGA vertical transition between the same board materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings described herein are used to provide a further understanding of the embodiments of the present utility model, constitute a part of this application, and do not constitute a limitation of the embodiments of the present utility model. In the drawings:

[0028] Figure 1 It is a cross-sectional view of the radio frequency signal transmission structure in the embodiment of the utility model;

[0029] Figure 2 This is a general schematic diagram of the radio frequency signal transmission structure in the embodiment of the present utility model;

[0030] Figure 3 This is a schematic diagram of the distribution of metal through holes in one layer of a PCB motherboard in an embodiment of the utility model;

[0031] Figure 4 This is a schematic diagram of a vertical transition structure in a PCB motherboard in an embodiment of the utility model;

[0032] Figure 5 Schematic diagram of the BGA radio frequency pad and the BGA ground pad on the top layer of the PCB motherboard in the embodiment of the utility model;

[0033] Figure 6 A schematic diagram of a radio frequency pad in a BGA vertical transition structure in an embodiment of the utility model;

[0034] Figure 7 A schematic diagram of the distribution of metal through holes in one layer of a BGA vertical transition structure in an embodiment of the utility model;

[0035] Figure 8 A schematic diagram of the distribution of another layer of metal through holes in the BGA vertical transition structure in an embodiment of the utility model;

[0036] Fig. 9 A schematic diagram of the distribution of another layer of metal through holes in the BGA vertical transition structure in an embodiment of the utility model;

[0037] Fig.10 A schematic diagram of the distribution of another layer of metal through holes in the BGA vertical transition structure in an embodiment of the utility model;

[0038] Fig.11 A schematic diagram of a pad for gold wire bonding between HTCC and an organic composite substrate in an embodiment of the utility model;

[0039] Fig.12 This is a schematic diagram of the distribution of grounding metal through holes in one layer of the organic composite substrate in the embodiment of the utility model;

[0040] Fig.13 A schematic diagram of the distribution of grounding metal through holes in another layer of the organic composite substrate in an embodiment of the utility model;

[0041] Fig.14 A schematic diagram of a pad for bonding HTCC and a gold wire of an organic composite substrate in an embodiment of the utility model;

[0042] Fig.15 It is a graph of return loss and insertion loss vs. frequency of the radio frequency signal transmission structure in the embodiment of the utility model. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical scheme and advantages of the embodiments of the utility model clearer, the technical scheme in the embodiments of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Generally, the components of the embodiments of the utility model described and shown in the drawings here can be arranged and designed in various different configurations.

[0044] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the present invention to be protected, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0046] In the description of the embodiments of the present utility model, it should be noted that if the terms "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the accompanying drawings, or is the orientation or position relationship in which the utility model product is usually placed when used. It is only for the convenience of describing the utility model and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present utility model.

[0047] In addition, the terms "horizontal", "vertical", "overhanging" and the like do not mean that the components must be absolutely horizontal or overhanging, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0048] In the description of the embodiments of the present invention, "multiple" means at least 2.

[0049] In the description of the embodiments of the present utility model, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0050] Embodiment 1: This embodiment provides a radio frequency signal transmission structure, such as Figure 1-Figure 14 As shown, Figure 4 The middle filling part is the vertical transition structure in the PCB motherboard. Figure 5 The filled part in the middle is the BGA RF pad on the top layer of the PCB motherboard, and the other shaded areas are the BGA ground pads on the top layer of the PCB motherboard; Figure 6The shaded part is the RF pad. Figure 7-10 Schematic diagram of metal via distribution in each layer. Fig.11 The middle filling part is the pad for gold wire bonding between HTCC and organic composite substrate; Figure 12-13 This is a schematic diagram of the distribution of grounding metal vias on each layer. Fig.14 The solid area in the middle is a microstrip transmission line of an organic composite substrate; the transmission structure includes a coaxial connector, a PCB motherboard, a BGA vertical transition structure, a HTCC substrate and an organic composite substrate which are connected in sequence, wherein: the BGA vertical transition structure, the HTCC substrate and the organic composite substrate are overlapped in sequence above the PCB motherboard, the PCB motherboard, the BGA vertical transition structure and the HTCC substrate are connected in sequence through respectively arranged radio frequency pads, the BGA vertical transition structure is also provided with an array solder ball, and the radio frequency pad of the BGA vertical transition structure is located in the middle of the array solder ball.

[0051] Optionally, the coaxial connector and the PCB motherboard are connected via a microstrip line and a stripline that are interconnected, the microstrip line is connected to the output end of the coaxial connector, and the stripline is connected to the input end of the PCB motherboard.

[0052] Optionally, the radio frequency pad of the HTCC substrate is connected to the input end of the organic composite substrate through a gold wire.

[0053] Among them, based on the current mainstream HTCC and BGA process levels, ANSYS Electronics is used to establish simulation models such as Figure 1 and 2 As shown, Figure 1 is a cross-sectional view of the structure. Figure 2 is a three-dimensional diagram of the structure; the model consists of an air cavity in a vertical transition structure, an organic composite substrate, an HTCC substrate, a BGA array, a metal shielding through hole, an RF metal through hole and a PCB board; the signal transmission path of the model can be decomposed into the RF signal transitioning from the SMP insulator to the microstrip line, and then through the microstrip-stripline conversion (see Figure 4 ) The RF metal through-holes of the stripline are vertically interconnected with the BGA solder balls that transmit RF signals on the PCB board (see Figure 5 and Figure 6 ), the RF BGA solder ball transitions to the HTCC top pad through the HTCC RF metal through hole (see Fig.11 ), HTCC top pad and the "T" pad in the organic composite substrate (see Fig.14 ) The RF signal is transmitted from the HTCC to the organic composite substrate output through two gold wire bonds; the metal shielding through holes arranged on both sides of the transmission line in the HTCC substrate and the PCB substrate and the grounded BGA solder balls in the BGA array can suppress the leakage of the RF signal and improve the return loss of the model.

[0054] Specifically, establish Figure 1 After the three-dimensional model is shown, the surface transmission line of the HTCC substrate circuit and the PCB substrate circuit are calculated according to the transmission line matching theory and relevant engineering experience, and the optimization results are used as initial values. Figure 1 The model was optimized by joint simulation using ANSYS Electronics. Then, the independent transmission structure was optimized and simulated. The return loss (S11 parameter, Fig.15 Insertion loss (S21 parameter, Fig.15 The lower and middle curves) Fig.15 According to the above simulation results, it can be seen that the return loss of the vertical interconnection structure is less than -10dB in the full frequency band of 0.1GHz to 20GHz, and the insertion loss is no more than 0.6dB in the full frequency band of 0.1GHz to 20GHz.

[0055] Embodiment 2: This embodiment provides a radio frequency signal transmission structure, including a coaxial connector, a PCB motherboard, a BGA vertical transition structure, an HTCC substrate and an organic composite substrate connected in sequence, wherein: the dielectric model of the microstrip line and the stripline is TSM-DS3M, wherein: the number of dielectric layers of the microstrip line is 1 layer, the number of dielectric layers of the stripline is 2 layers, and the thickness of the single-layer dielectric of the microstrip line and the stripline is 0.254mm. The width of the conductive strip of the microstrip line is 0.62mm. The width of the conductive strip of the above-mentioned stripline is 0.3mm.

[0056] Optionally, the PCB motherboard includes a first substrate, a second substrate and a third substrate stacked in sequence, such as Figure 3-Figure 5 As shown, where:

[0057] The first substrate, the second substrate and the third substrate are respectively penetrated by a plurality of metal through holes whose positions correspond to each other; the second substrate is provided with a transition structure, the upper end surface of the third substrate is provided with a radio frequency pad of the PCB motherboard, and the transition structure is connected to the radio frequency pad of the PCB motherboard, and the upper end surface of the third substrate is also provided with a connecting pad corresponding to the array solder ball of the BGA vertical transition structure.

[0058] Optionally, the BGA vertical transition structure includes a fourth substrate, a fifth substrate, a sixth substrate, a seventh substrate, an eighth substrate and a ninth substrate which are overlapped in sequence, such as Figure 6-Figure 11 As shown, where:

[0059] The array solder balls are arranged on the fourth substrate, the fifth substrate and the sixth substrate are penetrated by metal through holes corresponding to those in the PCB motherboard, the seventh substrate, the eighth substrate and the ninth substrate are also provided with first through holes around the RF pads; the upper end surface of the ninth substrate is provided with a RF pad of a BGA vertical transition structure.

[0060] Optionally, the organic composite substrate comprises a tenth substrate, an eleventh substrate and a twelfth substrate stacked in sequence, such as Figure 12-14 As shown, where:

[0061] The tenth substrate and the eleventh substrate are penetrated by a plurality of evenly distributed second through holes, the upper end surface of the twelfth substrate is provided with a microstrip transmission line, and the RF pad of the HTCC substrate is connected to one end of the microstrip transmission line through a gold wire; in the above-mentioned PCB motherboard, BGA vertical transition structure and organic composite substrate, the thickness of each layer of the substrate is 0.1 mm.

[0062] Among them, the RF signal of the broadband RF BGA vertical transition structure first transitions to the microstrip line and the stripline through the coaxial insulator of the SMP, vertically transitions to the BGA array through the PCB motherboard, and vertically transitions from the BGA array to the SIP substrate HTCC, and then is transmitted to the organic composite substrate output through gold wire bonding; metal shielding through holes are arranged around the transmission path to constrain the electromagnetic signal, and the transmission structure parameters can be appropriately changed and optimized to be applicable to HTCC and organic composite substrate substrate circuits with different numbers of layers and different parameters, and the derivability is strong; the stripline medium is TSM-DS3M, and the single-layer thickness is 0.254mm; the number of dielectric layers is 2, and the microstrip line medium is TSM-DS3M, and the single-layer thickness is 0.254mm; the number of dielectric layers is 1. Both microstrip and stripline use 50Ω standard lines, of which the conduction width of the microstrip line is 0.62mm; the conduction width of the stripline is 0.3mm; other conditions such as dielectric loss and metal thickness simulate the actual situation (metal thickness 18um, dielectric loss 0.002). The SIP includes an HTCC substrate shell and an organic composite substrate; the HTCC single layer thickness is 0.1mm; the number of dielectric layers is 5. The organic composite substrate medium is M6, with a single layer thickness of 0.1mm; the number of dielectric layers is 3. The BGA array in this structure can meet different BGA packaging forms, improving the interchangeability and versatility of SIP products. The BGA vertical transition structure in the RF signal transmission structure is suitable for the vertical transition of BGA between different substrates, expanding the use scenarios of the traditional BGA vertical transition between the same board materials.

[0063] The specific implementation methods described above further illustrate the purpose, technical solutions and beneficial effects of the utility model in detail. It should be understood that the above description is only the specific implementation method of the utility model and is not used to limit the protection scope of the utility model. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the utility model should be included in the protection scope of the utility model.

Claims

1. A radio frequency signal transmission structure, characterized in that: It includes a coaxial connector, a PCB motherboard, a BGA vertical transition structure, a HTCC substrate and an organic composite substrate connected in sequence, wherein: The BGA vertical transition structure, the HTCC substrate and the organic composite substrate are sequentially overlapped on the PCB motherboard, and the PCB motherboard, the BGA vertical transition structure and the HTCC substrate are sequentially connected through respectively arranged radio frequency pads, and the BGA vertical transition structure is also provided with an array solder ball, and the radio frequency pad of the BGA vertical transition structure is located in the middle of the array solder ball; The coaxial connector and the PCB motherboard are connected via a microstrip line and a stripline that are connected to each other. The microstrip line is connected to the output end of the coaxial connector, and the stripline is connected to the input end of the PCB motherboard.

2. The radio frequency signal transmission structure according to claim 1, characterized in that: The radio frequency pad of the HTCC substrate is connected to the input end of the organic composite substrate through a gold wire.

3. The radio frequency signal transmission structure according to claim 1, characterized in that: The dielectric model of the microstrip line and the stripline is TSM-DS3M, wherein: The number of dielectric layers of the microstrip line is 1, the number of dielectric layers of the strip line is 2, and the thickness of the single-layer dielectric of the microstrip line and the strip line is 0.254 mm.

4. The radio frequency signal transmission structure according to claim 1, characterized in that: The conducting strip width of the microstrip line is 0.62 mm.

5. The radio frequency signal transmission structure according to claim 1, characterized in that: The conductive strip width of the strip line is 0.3 mm.

6. A radio frequency signal transmission structure according to any one of claims 1 to 5, characterized in that: The PCB motherboard comprises a first substrate, a second substrate and a third substrate which are overlapped in sequence, wherein: The first substrate, the second substrate and the third substrate are respectively penetrated by a plurality of metal through holes whose positions correspond to each other; the second substrate is provided with a transition structure, the upper end surface of the third substrate is provided with a radio frequency pad of the PCB motherboard, and the transition structure is connected to the radio frequency pad of the PCB motherboard, and the upper end surface of the third substrate is also provided with a connecting pad corresponding to the array solder ball of the BGA vertical transition structure.

7. The radio frequency signal transmission structure according to claim 6, characterized in that: The BGA vertical transition structure comprises a fourth substrate, a fifth substrate, a sixth substrate, a seventh substrate, an eighth substrate and a ninth substrate which are overlapped in sequence, wherein: The array solder balls are arranged on the fourth substrate, the fifth substrate and the sixth substrate are penetrated by metal through holes corresponding to the PCB motherboard, the seventh substrate, the eighth substrate and the ninth substrate are also provided with first through holes around the RF pads; the upper end surface of the ninth substrate is provided with a RF pad of a BGA vertical transition structure.

8. The radio frequency signal transmission structure according to claim 7, characterized in that: The organic composite substrate comprises a tenth substrate, an eleventh substrate and a twelfth substrate which are stacked in sequence, wherein: The tenth substrate and the eleventh substrate are both penetrated by a plurality of evenly distributed second through holes, the upper end surface of the twelfth substrate is provided with a microstrip transmission line, and the RF pad of the HTCC substrate is connected to one end of the microstrip transmission line through a gold wire.

9. The radio frequency signal transmission structure according to claim 8, characterized in that: In the PCB motherboard, the BGA vertical transition structure and the organic composite substrate, the thickness of each layer of the substrate is 0.1 mm.

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