1. suspension bridge effect: in the case of high-density wiring, when there is not enough space between the two lines, there may be a line suspended on the other line, similar to the suspension bridge shape. The drawbridge effect often occurs in PCB designs, especially when a large number of signal lines need to be laid out and space is limited. The drawbridge effect can cause problems such as signal crosstalk, electromagnetic interference, and signal distortion or delay.
Measures to reduce the drawbridge effect
Reasonable planning of the PCB layout, as far as possible to maintain the linear layout of the signal line, to avoid the occurrence of line crossing or overlapping.
Optimize PCB routing, maximize the spacing between signal lines, and avoid the drawbridge effect caused by too small space.
The use of circuit board layering design, in different levels of the layout of different signal lines, reduce the cross between the lines and interference.
Through the appropriate signal layer and stratum planning, the electromagnetic interference between the signal lines is reduced, and the anti-interference ability of the circuit is improved.
2. ripple effect: in high-speed circuits, when the signal transmission speed is faster, the signal may produce ripple deformation when propagating on the circuit board, affecting the signal quality, including signal distortion, clock offset, crosstalk and interference.
Measures to reduce ripple effects
Optimize PCB layout and routing, minimize bending, crossing and branching of signal lines, and maintain signal transmission path consistency.
Using the appropriate signal line and ground design, reduce the crosstalk and interference between the signal lines, improve the signal transmission quality.
Use signal compensation technology or signal pre-emphasis technology to compensate and enhance the signal to reduce waveform distortion and deformation.
Select the appropriate signal transmission line and signal processing device to improve the anti-interference ability and transmission speed of the signal.
3. overshoot effect: The sudden voltage change during signal transmission may cause the components on the circuit board to be subjected to excessive voltage impact, damage the components or cause circuit failure. The overshoot effect may be caused by the rising or falling edge of the signal too fast, or it may be caused by the instability of the signal transmission line or the instability of the signal source.
Measures to reduce overshoot effects
Optimize the design of signal transmission line to ensure the impedance matching and stability of signal line.
Use suitable power filters and power decoupling capacitors to reduce signal source interference.
Signal pre-weighting technology or signal compensation technology is used to pre-process or compensate the signal to reduce the occurrence of overshoot effect.
Select the appropriate components and circuit protection devices to improve the anti-overshoot ability and stability of the circuit.
4. resonance effect: parameters such as inductance, capacitance and impedance on the circuit board may cause the signal to resonate at a specific frequency, affecting the stable transmission of the signal. This resonance phenomenon usually occurs at a specific frequency, when the frequency of the external signal matches the natural frequency of the circuit, causing a resonance effect.
Measures to reduce resonance effects
Optimize PCB layout and design to avoid the presence of natural frequencies and external excitation frequencies in the circuit.
Use compensation circuits or filters to eliminate or suppress resonant effects.
Select the appropriate damping element or damping material to reduce the influence of resonance effect.
The frequency response of the circuit is stable in a specific frequency range by using appropriate circuit tuning technology.
5. suspension effect: In high-speed circuits, due to electromagnetic radiation and other factors, the signal may be suspended on the surface of the wire or circuit board, affecting the transmission and reception of the signal. In order to reduce the PCB suspension effect on the circuit, the designer can take the following measures:
Measures to reduce suspension effects
Optimize PCB layout and design, reasonably plan the direction and spacing of signal lines, and minimize the impact of electromagnetic radiation on signal transmission.
Use the appropriate signal line and ground design to ensure the impedance matching and stability of the signal line.
Use shields or shielding materials to reduce electromagnetic radiation and interference.
Select appropriate board materials and components to reduce the occurrence of suspension effects.
6. crosstalk effect: due to the dense layout between PCB signal lines or electromagnetic interference and other factors, the phenomenon of signal crosstalk may occur between different signal lines. Signal crosstalk can cause signal quality degradation or circuit malfunction.
Measures to reduce crosstalk effects
Optimize PCB layout and design, reasonably plan the direction and spacing of signal lines, and minimize mutual interference between signal lines.
Use techniques such as shielding enclosures, shielding materials, or ground isolation to reduce the impact of electromagnetic interference on the signal.
Use differential signal transmission line or add signal layer to improve anti-interference ability and reduce the occurrence of crosstalk effect.
Select the right board materials and components to reduce the impact of crosstalk effects.
7. reflection effect: refers to the high-speed signal transmission, because the signal propagates in the PCB circuit impedance mismatch or the terminal of the signal transmission line does not fully absorb the energy of the signal, resulting in the signal reflection back to the original source. This reflection effect may lead to distortion of signal waveform and affect the transmission quality and stability of the circuit.
Measures to reduce reflection effects
Reasonably design the signal transmission line to ensure the impedance matching of the line and minimize the impedance mismatch.
Use components such as terminal resistors or terminal capacitors to absorb the energy of the signal and reduce the reflection of the signal.
Optimize PCB layout and design to minimize the length of signal transmission lines and reduce signal transmission delays.
Select appropriate board materials and components to reduce the impact of reflection effects.
8. shielding effect: the metal layer on the PCB board or shielding cover may have a shielding effect on the signal, affecting the transmission range and quality of the signal.
Measures to reduce the shielding effect
Reasonable design of PCB layout: try to avoid the overlap or proximity between the signal line and the shielded area to reduce the impact of the shielding effect.
Select the right shielding material: Select the right metal layer or shielding material in the PCB design, so that it has good shielding performance, while minimizing the impact on signal transmission.
Design a suitable grounding structure: a good grounding structure can help reduce the shielding effect of the signal and improve the transmission quality of the signal.
Note signal adjustment: For signals that need to pass through the shielded area, signal adjustment technology can be used to reduce the impact of the shielding effect, such as increasing the signal power or adjusting the signal transmission mode.
9. thermal expansion effect: temperature changes may lead to thermal expansion or contraction of PCB board materials, affecting the dimensional stability of the circuit board and the connection status of components.
Measures to reduce the effect of thermal expansion
Select the right PCB material: Select PCB material with small thermal expansion coefficient can reduce the influence of thermal expansion effect on the circuit.
Reasonable design of PCB layout: In the PCB design process, try to avoid directly connecting materials with high thermal expansion coefficient and low thermal expansion coefficient to reduce the influence of thermal expansion effect.
Control welding temperature: During the welding process, control the welding temperature and time to avoid excessive temperature resulting in solder joint rupture or component displacement.
The use of support structure: Adding a suitable support structure to the PCB board design can reduce the bending deformation of the PCB board and improve the stability and reliability of the PCB board.
10. Ground hole effect: There are a large number of ground holes on the PCB board, and when the distance between the local hole and the signal line or other ground holes is relatively close, the ground hole effect may occur, affecting the stability of signal transmission.
Measures to reduce ground hole effect
Reasonable design of ground holes: design suitable ground hole parameters, such as aperture, hole distance, copper foil diameter, etc., to ensure the impedance matching and consistency of the ground hole, reduce the inductance and crosstalk effect of the ground hole.
Using ground hole filling: When designing PCB, ground hole filling technology can be used to fill ground holes, reduce the impact of ground holes on signal transmission, and improve the performance stability of PCB board.
Optimize layout: rationally plan PCB layout, minimize the number and density of ground holes, and reduce the influence of ground hole effect on the circuit.
Adjust the stacking between layers: Choose the stacking mode between layers of the PCB board reasonably, minimize the ground hole between the inner layer and the outer layer, and reduce the influence of the ground hole effect.
11. filling effect: the filling material on the PCB board may have an impact on signal transmission, such as the dielectric constant of the filling material is different, which may lead to a change in signal transmission speed or signal attenuation.
Measures to reduce filling effects
Reasonable selection of filling materials: Select a filling material with a dielectric constant similar to the PCB board material to reduce the impact of the dielectric constant difference on signal transmission.
Control the thickness of the filling material: reasonably control the thickness of the filling material to avoid the extension of the signal transmission path and the increase of attenuation caused by the thickness of the filling material.
Optimize the PCB layout: When designing the PCB, minimize the impact on the signal transmission path, rationally plan the filling area, and avoid the interference of the filling material on the signal transmission path.
Use low loss filling materials: Select filling materials with low resistance and dielectric loss to reduce attenuation and distortion during signal transmission.
12. temperature drift effect: the temperature change on the PCB board may lead to the thermal expansion or contraction of the circuit board material, which affects the dimensional stability of the circuit board and the connection status of the components.
Measures to reduce the effect of temperature drift
Reasonable selection of PCB materials: Select PCB materials with good thermal stability and dimensional stability to reduce the impact of temperature changes on the PCB board.
Control welding temperature: During the welding process, control the welding temperature and time to avoid excessive welding temperature resulting in damage or fracture of components and welding points.
Optimize PCB layout: rationally plan PCB layout, reduce the difference in thermal expansion coefficient between components, and avoid temperature changes caused by changes in the connection state between components.
Temperature environment control: Control the temperature change in the PCB use environment, avoid the PCB board is subjected to a large temperature impact, and reduce the impact of temperature changes on the PCB circuit.
13. crystal effect: transistors and other devices in PCB wiring may be affected by the surrounding environment, resulting in changes in device parameters, affecting the performance of the circuit.
Measures to reduce crystal effects
Reasonable layout: Reasonable planning of PCB layout to avoid the influence of external interference on devices such as transistors and minimize the interference of electromagnetic fields on devices.
Temperature control: In the PCB design and manufacturing process, measures are taken to control the working temperature of the PCB board, reduce the impact of temperature changes on the device parameters, and improve the stability of the circuit.
Select the right device: Select devices such as transistors with good anti-interference and stability to reduce the influence of crystal effects on the circuit.
Design compensation circuit: In PCB design, compensation circuit can be used to correct the drift of device parameters such as transistors and improve the performance and stability of the circuit.
14. limited effect: there are some limited areas on the PCB board, such as edges, power supply areas, etc., which may cause certain restrictions or effects on signal transmission or wiring.
Measures to reduce limiting effects
Reasonable planning layout: In PCB design, reasonable planning layout, try to avoid placing sensitive signal lines or components near the restricted area, reduce the impact of restrictions.
Electromagnetic shielding: For the restricted area is vulnerable to electromagnetic interference, electromagnetic shielding measures can be taken, such as metal shielding around the sensitive area to reduce the impact of external electromagnetic interference on the circuit.
Optimization of power supply design: For the power supply instability or noise problems that may exist in the power supply area, measures can be taken to optimize the power supply design, such as increasing the filter circuit, reducing the power supply noise, etc., to improve the power supply stability and performance of the circuit.
Fine wiring: When wiring in a restricted area, try to use fine wiring to reduce the limitation or extension of the signal transmission path, and improve the rate and stability of signal transmission.
15. mine effect: The invisible problem or hidden fault on the PCB board may suddenly appear in the subsequent test or use process, bringing unexpected impact or damage to the circuit board.
Measures to reduce the effects of landmines
Strict quality control: In the PCB production process, the quality of each link is strictly controlled to ensure that each component and circuit connection meet the specifications and reduce hidden dangers.
Improve the test process: Establish a sound test and inspection process, conduct a comprehensive test and inspection of PCB circuits, and timely discover and repair potential problems.
Use reliable components: Select components and materials with high reliability and stable quality to reduce the probability of failure and reduce the occurrence of mine effects.
Strengthen maintenance: Regular maintenance and maintenance of the PCB circuit that has been produced, timely discovery and repair potential problems, and improve the reliability and stability of the circuit.
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