Missile-borne radio frequency rigid-flex printed board assembly

Abstract

A missile-borne radio frequency rigid-flex printed board assembly comprises a rigid-flex printed board and a connector. The rigid-flex printed board is of a laminated structure, both ends of which are rigid regions, and the flexible region of the rigid-flex printed board is between the two rigid regions. The top layer and the bottom layer of the rigid region are rigid layers, the inner layer between the rigid layers is a flexible layer, the laminated layers of the flexible region are flexible layers, and the flexible layers of the inner layers of the rigid regions are integrally arranged. The connector is arranged on the rigid region of the rigid-flex printed board. The flexible region of the assembly can ensure the signal integrity of the transmitted radio frequency signal and the bending property of the flexible region at the same time, and can be used in a small space. The assembly integrates the transmission of radio frequency signals, control signals and power signals, has small volume, wide application range, good versatility and low cost.

Description

Technical Field

[0001] This invention relates to a flexible board assembly, specifically to a radio frequency rigid-flex printed circuit board assembly for missile launch vehicles. Background Technology

[0002] To meet the current requirements for miniaturization, lightweighting, and integration of missile-borne products, flexible circuit board (FPCB) assemblies are often used. FPCB assemblies can operate reliably for extended periods in harsh environments such as high and low temperatures, high humidity, vibration, salt spray, and low air pressure. FPCB assemblies are system modules composed of flexible circuit boards and electronic components. They not only replace cable assemblies to achieve highly reliable signal transmission but also function as carriers for circuit components.

[0003] Flexible board (Flexible Board) assemblies offer the following advantages: they are slim and lightweight, with signal lines densely packed in printed circuit boards, resulting in small component size and light weight; they extend circuit board applications from two-dimensional to three-dimensional space, enabling 3D assembly, and interfaces are not limited by position or angle; the interconnection of printed circuit lines in Flexible Board assemblies relies on CAD design and prefabrication, eliminating wire connection steps, improving production efficiency, and ensuring product consistency. Flexible Board assemblies enable cableless designs, improving product reliability and optimizing product layout space.

[0004] As the integration of various signals in flexible printed circuit board (FPCB) assemblies increases, the requirements for the product's radio frequency (RF) signal transmission capabilities also become more stringent. Currently, rigid-flex PCBs for RF signals are not yet used in missile-borne environments. In existing missile-borne environments, the mixed use of RF cables and rigid-flex PCBs leads to wasted space, large size, poor versatility, high cost, and inability to bend in confined spaces. Therefore, a rigid-flex PCB assembly suitable for integrating and transmitting 90–150 MHz RF signals, control signals, and power signals is needed in missile-borne environments. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a radio frequency rigid-flex printed circuit board assembly for missile launchers.

[0006] The objective of this invention is achieved through the following technical solution. According to this invention, a radio frequency rigid-flex printed circuit board (RCB) assembly for missile launchers includes a RCB and a connector. The RCB has a stacked structure, with rigid regions at both ends and a flexible region between the two rigid regions. The top and bottom layers of the rigid regions are rigid layers, and the inner layer between the rigid layers is a flexible layer. All layers of the flexible region are flexible layers and are integrally formed with the flexible layer within the rigid region. The connector is disposed on the rigid region of the RCB.

[0007] Furthermore, the connector is a high- and low-frequency mixed connector.

[0008] Furthermore, the connector adopts a through-hole soldering termination method to be directly soldered and fixed to the rigid-flex printed circuit board. The pins on the connector are directly inserted into the soldering holes on the rigid-flex printed circuit board, and the pins of the connector are soldered to the soldering holes on the rigid-flex printed circuit board to fix the connector to the rigid-flex printed circuit board.

[0009] Furthermore, the copper layers of the flexible region stacked structure of the rigid-flex printed circuit board are sequentially G1 layer, S2 layer, G3 layer, S4 layer, G5 layer, S6 layer, P7 layer, and P8 layer, which are divided into three pieces. The first piece is composed of layers from G1 to S4, the second piece is composed of layers from G5 to S6, and the third piece is composed of layers from P7 to P8. Each stacked structure is separated by an air gap, and each stack is separated by a corresponding CORE. Each stack uses copper.

[0010] Furthermore, the CORE material is made of Polyimide or Polyester and has a thickness of 4 mil.

[0011] Furthermore, the copper is selected from rolled copper foil.

[0012] Furthermore, the S2 layer serves as the transmission layer for radio frequency signals. The S2 layer adopts a PCB stripline structure, with a copper thickness of 0.5 oz, and uses the G1 and G3 layers as reference layers.

[0013] Furthermore, in the S2 layer, the trace width of the single-ended RF signal line is 10mil, which is wrapped by the ground layers G1 and G3 above and below. In addition, the RF signal trace is wrapped by the same layer shield ground, which is 45mil away from the RF signal trace.

[0014] Furthermore, the total thickness of the rigid-flex printed circuit board is 2mm, and the minimum bending radius of the flexible area is 8.8mm.

[0015] Furthermore, the flexible region does not have isolation holes, and each signal trace in each signal transmission layer is separated by a shielded ground.

[0016] Compared with the prior art, the advantages of the present invention are:

[0017] The flexible area of ​​this component ensures the signal integrity of the transmitted radio frequency signal while also allowing for bending, enabling its use in confined spaces. This component integrates the transmission of radio frequency signals, control signals, and power signals, is small in size, has a wide range of applications, and thus offers good versatility and low cost.

[0018] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of an embodiment of a radio frequency rigid-flex printed circuit board assembly for missile launchers according to the present invention.

[0020] Figure 2 for Figure 1 Schematic diagram of the laminated structure of a rigid-flex printed circuit board.

[0021] [Attached image labels]

[0022] 1-Connector, 2-Rigid-flexible printed circuit board, 201-Rigid area, 202-Flexible area. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] An embodiment of the present invention provides a radio frequency rigid-flex printed circuit board assembly for missile-borne applications, such as... Figures 1 to 2 As shown, hereinafter referred to as the component. The component includes a connector 1 and a rigid-flex printed circuit board 2. The connector 1 is a high- and low-frequency mixed connector. Connectors 1 are provided at both ends of the rigid-flex printed circuit board. The connectors 1 are directly soldered to the rigid-flex printed circuit board using a through-hole soldering termination method. The pins of the connector 1 are directly inserted into the soldering holes on the rigid-flex printed circuit board, and the pins of the connector are soldered to the soldering holes on the rigid-flex printed circuit board, so that the connector 1 and the rigid-flex printed circuit board 2 are soldered and fixed.

[0025] The rigid-flex printed circuit board 2 has a strip-shaped laminated structure, with rigid regions 201 at both ends and flexible regions 202 between the two rigid regions 201. The laminate names, laminate types, thicknesses, and materials of the different regions are shown in Table 1. Figure 2 As shown. The top and bottom layers at both ends of the rigid-flex printed circuit board are rigid layers, and the inner layer between the rigid layers is a flexible layer. The end area of ​​the rigid-flex printed circuit board covered by the rigid layers is the rigid region 201 of the rigid-flex printed circuit board. The stacked layers of the flexible region 202 are all flexible layers and are integrally formed with the flexible layer of the inner layer of the rigid region 201. The connector 1 is disposed on the rigid region of the rigid-flex printed circuit board and is welded and fixed to the rigid layer.

[0026]

[0027]

[0028] Table 1. Materials and thicknesses of the laminated structures

[0029] The flexible area stack-up structure of the rigid-flex printed circuit board includes multiple copper layers, divided into three pieces. The first piece is composed of layers G1 to S4, the second piece is composed of layers G5 to S6, and the third piece is composed of layers P7 to P8, as shown in Table 2. Each stack-up structure is separated by an air gap, and each stack-up is separated by a corresponding CORE (material), i.e., Dielectric in Table 1. The material used is the commonly used Polyimide (PI), and each stack-up uses copper foil.

[0030] To ensure the signal integrity of RF signals transmitted in the flexible area while also considering its flexibility, the RF signals are transmitted on the S2 layer of the first wafer in the design of the flexible area's stack-up structure. The S2 layer serves as the RF signal transmission layer, employing a PCB stripline structure with a copper thickness of 0.5 oz. Using the G1 and G3 layers as reference layers, layers G1 to S4 are laminated together to ensure complete upper and lower references for the RF signal traces. The second and third wafers are used to transmit control signals and power signals, respectively.

[0031] The substrate (Dielectric) adjacent to the S2 layer is made of polyimide with a thickness of 4mil, and the copper foil of the S2 layer is 0.5oz thick; the total thickness of the rigid-flex printed circuit board is 2mm, and the minimum bending radius of the flexible area is 8.8mm, which meets the space requirements for product installation and use.

[0032] In layer S2, the trace width of the single-ended RF signal line is 10mil, which is wrapped by the ground layers G1 and G3 above and below. In addition, the RF signal trace is wrapped by the same layer shield ground, which is 45mil away from the RF signal trace.

[0033]

[0034] Table 2. Lamination structure of the flexible region of rigid-flexible printed circuit boards

[0035] In the laminated structure, the flexible material, namely the dielectric, is usually made of Polyimide (PI) or Polyester (PET), and the copper foil is rolled copper foil (RA).

[0036] The routing and pad design of the rigid-flex printed circuit board are consistent with the backplane design method in the existing technology, and will not be repeated here. Considering the bending nature of the flexible area, no isolation holes are made in the flexible area, but in each signal transmission layer, each signal trace is separated by a shielded ground.

[0037] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A radio frequency rigid-flex printed board assembly for missile-borne use, comprising a rigid-flex printed board, a connector, characterized in that: The rigid-flexible printed board is a laminated structure, both ends of which are rigid regions, and the flexible region of the rigid-flexible printed board is between the two rigid regions, the top layer and the bottom layer of the rigid region are rigid layers, the inner layer between the rigid layers is a flexible layer, the laminated structure of the flexible region is all flexible layers, and is integrally arranged with the flexible layer of the inner layer of the rigid region; the connector is arranged on the rigid region of the rigid-flexible printed board; the copper layer of the laminated structure of the flexible region of the rigid-flexible printed board is G1 layer, S2 layer, G3 layer, S4 layer, G5 layer, S6 layer, P7 layer and P8 layer in sequence, and is divided into three pieces, from G1 layer to S4 layer, which is synthesized into a first piece, from G5 layer to S6 layer, which is synthesized into a second piece, and from P7 layer to P8 layer, which is synthesized into a third piece, each piece of laminated structure is separated by an air gap, each layer is separated by a corresponding board material, and each layer uses copper foil; the S2 layer is a transmission layer of radio frequency signals, the G1 layer and the G3 layer are reference layers, the radio frequency signal single-ended line in the S2 layer is wrapped by the upper and lower ground layers G1 layer and G3 layer, and the radio frequency signal wire is wrapped by the shielding ground in the same layer; the second piece and the third piece are respectively used for transmitting control signals and power signals.

2. The radio frequency rigid-flex printed board assembly for a missile-borne use according to claim 1, characterized in that: The connector is a high-low frequency mixed connector.

3. The radio frequency rigid-flex printed board assembly for missile-borne use according to claim 1, characterized in that: The connector is directly welded and fixed with the rigid-flexible printed board in a form of direct insertion, perforation and welding termination, the pins on the connector are directly inserted into the welding holes on the rigid-flexible printed board, and the pins on the connector and the welding holes on the rigid-flexible printed board are welded, so that the connector is welded and fixed with the rigid-flexible printed board.

4. The radio frequency rigid-flex printed board assembly for a missile-borne application according to claim 1, characterized in that: The board material is selected from polyimide or polyester, and the thickness is 4 mil.

5. The radio frequency rigid-flex printed board assembly for a missile-borne application according to claim 1, wherein: The copper foil is selected from rolled copper foil.

6. The radio frequency rigid-flex printed board assembly for a missile-borne application according to claim 1, wherein: The S2 layer adopts a PCB strip line structure, and the copper thickness of the S2 layer is 0.5 oz.

7. The radio frequency rigid-flex printed board assembly for missile-borne use according to claim 1, characterized in that: In the S2 layer, the width of the radio frequency signal single-ended line is 10 mil, and the distance between the radio frequency signal wire and the shielding ground in the same layer is 45 mil.

8. The radio frequency rigid-flex printed board assembly for missile-borne use according to claim 1, characterized in that: The total thickness of the rigid-flexible printed board is 2 mm, and the minimum bending radius of the flexible region is 8.8 mm.

9. The radio frequency rigid-flex printed board assembly for a missile-borne application according to claim 1, wherein: The flexible region does not punch isolation holes, and in each signal transmission layer, each signal wire is separated by a shielding ground. The flexible region does not punch isolation holes, and in each signal transmission layer, each signal wire is separated by a shielding ground.

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