D. Decoupling Capacitor Configuration
In the DC power supply loop, changes in the load can lead to power supply noise. For instance, in digital circuits, transitioning from one state to another can result in a spike in current on the power line, causing transient noise voltage. The configuration of decoupling capacitors can mitigate the noise from load changes, a common practice in the reliability design of printed circuit boards. The following are the principles for configuration:
● Connect a 10-100uF electrolytic capacitor across the power input. If space on the printed circuit board allows, using an electrolytic capacitor above 100uF will provide better anti-interference effects.
● Install a 0.01uF ceramic capacitor for each integrated circuit chip. If space is limited and cannot accommodate, configure a 1-10uF tantalum electrolytic capacitor for every 4-10 chips. This device has very low high-frequency impedance, less than 1Ω in the range of 500kHz-20MHz, and minimal leakage current (less than 0.5uA).
● For components with weak noise tolerance and large current changes during turn-off, such as ROM, RAM, etc., a decoupling capacitor should be directly connected between the power line (Vcc) and ground (GND) of the chip.
● Keep the lead wires of decoupling capacitors short, especially for high-frequency bypass capacitors.
E. The Size of Printed Circuit Board And The Layout of The Device
The size of the printed circuit board should be moderate. If it is too large, the length of the printed lines and impedance will increase, reducing noise resistance and increasing costs. If it is too small, heat dissipation will be inadequate and may be vulnerable to interference from adjacent lines.
When it comes to device layout, devices related to each other, like other logic circuits, should be placed as close as possible for better anti-noise effects. Components like timers, crystal oscillators, and the CPU clock input are susceptible to noise and should be located near each other. Components prone to noise, low-current circuits, and high-current circuits should be separated from logic circuits as much as possible. If feasible, separate circuit boards should be used, as this is crucial.
Practical experience demonstrates that a well-planned device arrangement can effectively reduce the temperature rise of the printed circuit, leading to significantly lower device and equipment failure rates.
The above outlines the general principles of reliability design. It is evident that PCB board design is crucial, as these reliability designs directly impact the quality of the final circuit board and the product’s application performance.
WellCircuits Limited specializes in manufacturing high-precision double-sided, multi-layer, and impedance-controlled circuit boards, including blind buried vias and thick copper. They offer products such as HDI, thick copper, backplanes, rigid-flex combinations, buried capacitors, buried resistors, Golden Fingers, and more, catering to a wide range of customer needs.
In the DC power supply loop, changes in the load can lead to power supply noise. For instance, in digital circuits, transitioning from one state to another can result in a spike in current on the power line, causing transient noise voltage. The configuration of decoupling capacitors can mitigate the noise from load changes, a common practice in the reliability design of printed circuit boards. The following are the principles for configuration:
● Connect a 10-100uF electrolytic capacitor across the power input. If space on the printed circuit board allows, using an electrolytic capacitor above 100uF will provide better anti-interference effects.
● Install a 0.01uF ceramic capacitor for each integrated circuit chip. If space is limited and cannot accommodate, configure a 1-10uF tantalum electrolytic capacitor for every 4-10 chips. This device has very low high-frequency impedance, less than 1Ω in the range of 500kHz-20MHz, and minimal leakage current (less than 0.5uA).
● For components with weak noise tolerance and large current changes during turn-off, such as ROM, RAM, etc., a decoupling capacitor should be directly connected between the power line (Vcc) and ground (GND) of the chip.
● Keep the lead wires of decoupling capacitors short, especially for high-frequency bypass capacitors.
E. The Size of Printed Circuit Board And The Layout of The Device
The size of the printed circuit board should be moderate. If it is too large, the length of the printed lines and impedance will increase, reducing noise resistance and increasing costs. If it is too small, heat dissipation will be inadequate and may be vulnerable to interference from adjacent lines.
When it comes to device layout, devices related to each other, like other logic circuits, should be placed as close as possible for better anti-noise effects. Components like timers, crystal oscillators, and the CPU clock input are susceptible to noise and should be located near each other. Components prone to noise, low-current circuits, and high-current circuits should be separated from logic circuits as much as possible. If feasible, separate circuit boards should be used, as this is crucial.
Practical experience demonstrates that a well-planned device arrangement can effectively reduce the temperature rise of the printed circuit, leading to significantly lower device and equipment failure rates.
The above outlines the general principles of reliability design. It is evident that PCB board design is crucial, as these reliability designs directly impact the quality of the final circuit board and the product’s application performance.
WellCircuits Limited specializes in manufacturing high-precision double-sided, multi-layer, and impedance-controlled circuit boards, including blind buried vias and thick copper. They offer products such as HDI, thick copper, backplanes, rigid-flex combinations, buried capacitors, buried resistors, Golden Fingers, and more, catering to a wide range of customer needs.
