Flexible circuit board bending compensation signal impedance matching circuit

Abstract

The application discloses a flexible circuit board bending compensation signal impedance matching circuit, which comprises a flexible circuit board main body, a signal transmission line, an impedance compensation unit and a connecting terminal. The signal transmission line is arranged on the flexible circuit board main body, and the two ends of the signal transmission line are connected with the first connecting terminal and the second connecting terminal respectively; and the bending area is provided with the impedance compensation unit comprising a plurality of distributed compensation elements. In the preferred scheme, the compensation elements adopt a capacitor compensation structure composed of an electrode pair with an area of 0.01-0.1 mm2 and a dielectric layer with a thickness of 5-20 mu m, and a negative temperature coefficient thermistor with a resistance of 100 omega-1 k omega is additionally arranged to realize temperature compensation. The application dynamically adjusts the parasitic parameters of the bending area through the distributed impedance compensation unit, so that the signal transmission line (50-150 mu m line width) keeps the impedance stable in the bending state, and the signal integrity problem caused by the deformation of the existing flexible circuit board is solved. The circuit is particularly suitable for high-frequency signal transmission scenes, the impedance change rate is less than 3% when the bending radius is 5 mm, and the working frequency range covers DC-20 GHz.

Description

Technical Field

[0001] This invention belongs to the field of flexible circuit board technology, specifically a flexible circuit board bending compensation signal impedance matching circuit. Background Technology

[0002] Flexible printed circuit boards (FPCs) are widely used in electronic products due to their bendable and foldable properties. However, in the bending areas of FPCs, material deformation and structural changes cause changes in the impedance of signal transmission lines, thus affecting signal transmission quality. Especially in high-frequency signal transmission, this impedance mismatch can lead to signal reflection, attenuation, and distortion, severely impacting system performance.

[0003] In existing technologies, fixed impedance matching circuits are typically used to address impedance mismatch issues. However, this approach cannot adapt to impedance variations in FPCs under different bending conditions. Furthermore, temperature changes also affect the impedance characteristics of FPCs, and existing technologies often neglect the influence of temperature. Therefore, there is an urgent need for a circuit structure capable of dynamically compensating for impedance variations in the bending region of an FPC to maintain the integrity of signal transmission. Summary of the Invention

[0004] 1. Technical Problem Solved by this Implementation Scheme: To solve the problem of impedance change in signal transmission lines caused by deformation in the bending area of ​​a flexible circuit board, thereby improving signal transmission quality. Technical Solution Adopted in this Implementation Scheme: A flexible circuit board bending compensation signal impedance matching circuit, including a flexible circuit board body, a signal transmission line, an impedance compensation unit, a first connection terminal, and a second connection terminal. The signal transmission line is disposed on the flexible circuit board body, with its two ends connected to the first and second connection terminals respectively. An impedance compensation unit is disposed in the bending area of ​​the signal transmission line, and the impedance compensation unit includes multiple distributed compensation elements, which are uniformly distributed along the bending area of ​​the signal transmission line. Beneficial Effects of this Implementation Scheme: Through the distributed impedance compensation unit, the impedance characteristics of the bending area can be dynamically adjusted to maintain the integrity of signal transmission. Working Principle of this Implementation Scheme: Distributed compensation elements are disposed in the bending area of ​​the FPC, and the impedance change caused by bending is offset by adjusting the parameters of the compensation elements.

[0005] 2. Technical problem solved in the preferred embodiment: To provide a specific capacitance compensation scheme that precisely controls the capacitance parameters of the bending area. Technical solution adopted in the preferred embodiment: The distributed compensation element is a capacitance compensation element, which includes a first compensation electrode, a second compensation electrode, and a dielectric layer. The first and second compensation electrodes are respectively disposed on both sides of the signal transmission line, and the dielectric layer is disposed between the first and second compensation electrodes. Beneficial effect produced in the preferred embodiment: Through a precisely designed capacitance compensation element, capacitance changes caused by bending can be effectively compensated. Working principle: Utilizing the capacitance effect between electrodes to compensate for parasitic capacitance changes in the signal transmission line.

[0006] 3. Technical problem solved under preferred implementation: Optimizing the dimensional parameters of the capacitance compensation element to improve compensation accuracy. Technical solution adopted under preferred implementation: The area of ​​the first and second compensation electrodes is 0.01mm²–0.1mm², and the thickness of the dielectric layer is 5μm–20μm. Beneficial effects produced under preferred implementation: Accurate capacitance compensation can be achieved by optimizing the electrode area and dielectric layer thickness. Working principle: The capacitance value is directly proportional to the electrode area and inversely proportional to the dielectric layer thickness.

[0007] 4. Technical problem solved in the preferred implementation: compensating for the effect of temperature changes on impedance. Technical solution adopted in the preferred implementation: The impedance compensation unit also includes a temperature compensation element, which is located in the bending area of ​​the signal transmission line. Beneficial effect produced in the preferred implementation: The temperature compensation element can offset impedance changes caused by temperature variations. Working principle: Utilizing the characteristics of a temperature-sensitive element to compensate for impedance changes caused by temperature.

[0008] 5. Technical problem solved under preferred implementation: Selecting appropriate thermistor parameters. Technical solution adopted under preferred implementation: The temperature compensation element is a negative temperature coefficient thermistor with a resistance of 100Ω–1kΩ. Beneficial effect produced under preferred implementation: Effective temperature compensation can be achieved through appropriate thermistor parameters. Working principle: The resistance of the negative temperature coefficient thermistor decreases as temperature increases.

[0009] 6. Technical problem solved under preferred implementation: Optimizing the dimensional parameters of the signal transmission line. Technical solution adopted under preferred implementation: The linewidth of the signal transmission line is 50μm–150μm, and the thickness is 10μm–30μm. Beneficial effect produced under preferred implementation: By optimizing the signal transmission line dimensions, signal transmission quality can be improved. Working principle: The impedance of the signal transmission line is related to its geometric dimensions.

[0010] 7. Technical problem solved under preferred implementation: Selecting a suitable flexible circuit board material and thickness. Technical solution adopted under preferred implementation: The thickness of the flexible circuit board body is 50μm-200μm, and the material of the flexible circuit board body is polyimide. Beneficial effects produced under preferred implementation: Polyimide material has good flexibility and high-temperature resistance. Working principle: The dielectric constant and mechanical properties of polyimide are suitable for flexible circuit board applications.

[0011] 8. Technical problem solved in the preferred implementation: Optimizing the design of the connection terminals. Technical solution adopted in the preferred implementation: The first and second connection terminals are gold finger connectors with a spacing of 0.5mm–1.0mm. Beneficial effects of the preferred implementation: The gold finger connectors have good contact reliability and high-frequency characteristics. Working principle: The gold finger structure enables reliable electrical connection. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the overall structure of the flexible circuit board bending compensation signal impedance matching circuit.

[0013] Figure 2 This is a schematic diagram of the capacitor compensation element;

[0014] Figure 3 This is a schematic diagram of the working principle of a temperature compensation element.

[0015] 1. Flexible circuit board body; 2. Signal transmission line; 3. Impedance compensation unit; 31. Distributed compensation element; 311. First compensation electrode; 312. Second compensation electrode; 313. Dielectric layer; 32. Temperature compensation element; 4. First connection terminal; 5. Second connection terminal. Detailed Implementation

[0016] In the specific implementation process, such as Figure 1-3 As shown.

[0017] Example 1:

[0018] A flexible circuit board bending compensation signal impedance matching circuit includes a 100μm thick polyimide flexible circuit board body 1, on which a 100μm wide and 18μm thick signal transmission line 2 is disposed. The two ends of the signal transmission line 2 are respectively connected to a first connection terminal 4 and a second connection terminal 5, the connection terminals being gold finger connectors with a spacing of 0.8mm. An impedance compensation unit 3 is disposed in the bending area of ​​the signal transmission line 2. The impedance compensation unit 3 includes 12 distributed compensation elements 31, which are capacitive compensation elements, evenly distributed along the bending area. Each capacitive compensation element includes a first compensation electrode 311 and a second compensation electrode 312 with an area of ​​0.05mm², and a 10μm thick polyimide dielectric layer 313. Signal input → first connection terminal 4 → signal transmission line 2 → impedance compensation unit 3 → compensated signal → output from second connection terminal 5.

[0019] Example 2:

[0020] A flexible circuit board bending compensation signal impedance matching circuit includes a polyimide flexible circuit board body 1 with a thickness of 150 μm, on which a signal transmission line 2 with a width of 80 μm and a thickness of 15 μm is disposed. The two ends of the signal transmission line 2 are respectively connected to a first connection terminal 4 and a second connection terminal 5, and the connection terminals are gold finger connectors with a spacing of 0.6 mm. In addition, a negative temperature coefficient thermistor with a resistance of 500Ω is also provided as a temperature compensation element 32.

[0021] Example 3:

[0022] A flexible circuit board bending compensation signal impedance matching circuit includes a polyimide flexible circuit board body 1 with a thickness of 80μm, on which a signal transmission line 2 with a width of 120μm and a thickness of 20μm is disposed. The two ends of the signal transmission line 2 are respectively connected to a first connection terminal 4 and a second connection terminal 5, the connection terminals being gold finger connectors with a spacing of 1.0mm. An impedance compensation unit 3 is disposed in the bending area of ​​the signal transmission line 2. The impedance compensation unit 3 includes 6 distributed capacitance compensation elements 31 and 6 distributed compensation elements 31, alternately arranged in the bending area. The electrode area of ​​the capacitance compensation element 31 is 0.08mm², and the dielectric layer thickness is 15μm; the linewidth of the distributed compensation element 31 is 40μm, and the number of turns is 7. Two negative temperature coefficient thermistors with a resistance of 200Ω are also disposed as temperature compensation elements 32.

[0023] It should be noted that, in this document, the terms "comprising," "including," and any other variations are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Specific examples have been used in this document to illustrate the principles and implementation methods of the present invention. These examples are merely for the purpose of helping to understand the method and core ideas of the present invention. The above descriptions are only preferred embodiments of the present invention. It should be pointed out that, due to the limitations of written expression and the objective existence of infinite specific structures, those skilled in the art can make several improvements, modifications, or variations without departing from the principles of the present invention, and can also combine the above technical features in an appropriate manner. These improvements, modifications, variations, or combinations, or the direct application of the concept and technical solution of the present invention to other situations without modification, should all be considered within the scope of protection of the present invention.

Claims

1. A flexible circuit board bending compensation signal impedance matching circuit, characterized in that: The system includes a flexible circuit board body (1), a signal transmission line (2), an impedance compensation unit (3), a first connection terminal (4), and a second connection terminal (5). The flexible circuit board body (1) is provided with a signal transmission line (2), and the two ends of the signal transmission line (2) are respectively connected to the first connection terminal (4) and the second connection terminal (5). An impedance compensation unit (3) is provided in the bending area of ​​the signal transmission line (2). The impedance compensation unit (3) includes multiple distributed compensation elements (31), which are evenly distributed along the bending area of ​​the signal transmission line (2).

2. The flexible circuit board bending compensation signal impedance matching circuit according to claim 1, characterized in that: The distributed compensation element (31) is a capacitance compensation element, which includes a first compensation electrode (311), a second compensation electrode (312) and a dielectric layer (313). The first compensation electrode (311) and the second compensation electrode (312) are respectively disposed on both sides of the signal transmission line (2), and the dielectric layer (313) is disposed between the first compensation electrode (311) and the second compensation electrode (312).

3. The flexible circuit board bending compensation signal impedance matching circuit according to claim 2, characterized in that: The area of ​​the first compensation electrode (311) and the second compensation electrode (312) is 0.01 mm² to 0.1 mm², and the thickness of the dielectric layer (313) is 5 μm to 20 μm.

4. The flexible circuit board bending compensation signal impedance matching circuit according to claim 1, characterized in that: The impedance compensation unit (3) further includes a temperature compensation element (32), which is disposed in the bending area of ​​the signal transmission line (2).

5. The flexible circuit board bending compensation signal impedance matching circuit according to claim 4, characterized in that: The temperature compensation element (32) is a negative temperature coefficient thermistor with a resistance of 100Ω-1kΩ.

6. The flexible circuit board bending compensation signal impedance matching circuit according to claim 1, characterized in that: The line width of the signal transmission line (2) is 50μm-150μm, and the thickness of the signal transmission line (2) is 10μm-30μm.

7. The flexible circuit board bending compensation signal impedance matching circuit according to claim 1, characterized in that: The thickness of the flexible circuit board body (1) is 50μm-200μm, and the material of the flexible circuit board body (1) is polyimide.

8. The flexible circuit board bending compensation signal impedance matching circuit according to claim 1, characterized in that: The first connecting terminal (4) and the second connecting terminal (5) are gold finger connectors, and the spacing between the gold finger connectors is 0.5mm-1.0mm.

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