1. What problems should be addressed when using PCB components?
In PCB circuit board prototyping, the effective and reasonable use of components is crucial for the stability and quality of the board. So, what issues should be addressed during the PCB prototyping process?
1. Limit the output current to avoid the locking effect in CMOS circuits: The locking effect refers to the presence of parasitic PNP and NPN transistors within the CMOS circuit, forming a parasitic PNPN thyristor structure. A common solution is to use a resistor to isolate each output terminal from its connecting cable and to clamp the cable with two high-speed switching diodes to VDD (drain power) and VSS (source power).
2. Implement a filter network: When a long input cable is required between the CMOS circuit system and mechanical contacts, the risk of electromagnetic interference increases. Therefore, incorporating a filter network is advisable.
3. Forming an RC Network: For sensitive inputs on bipolar devices, use an RC network consisting of a high-value resistor and a capacitor of at least 100pF to mitigate the effects of electrostatic discharge.
4. Avoid Floating Input Pins on CMOS Devices: Floating input pins can cause instability in input potential, disrupting the circuit’s logical functions and making it susceptible to electrostatic breakdown and external noise interference. Redundant input terminals should be managed according to the circuit’s design requirements.
2. Simple Maintenance Skills and Production Process of Circuit Boards
Circuit boards are also known by various names, including PCB boards, aluminum substrates, high-frequency boards, thick copper boards, impedance boards, ultra-thin circuit boards, and printed (copper etching technology) circuit boards.
Circuit Board Repair Skills: Observation Method
This intuitive method involves inspecting the board to identify burnt traces. When using this approach, consider the following:
Step 1: Determine if the circuit board has been damaged manually by checking:
(1) Deformation of the board’s corners, chips, or other components.
(2) Signs of tampering with the chip and socket.
(3) Proper insertion of the circuit board chip, as damage can occur when power is applied.
(4) Correct insertion and orientation of short-circuit terminals.
Step 2: Examine all components related to the circuit board, including capacitors and resistors, for signs of blackening. Since resistance values are not visible, use an instrument to measure them. Replace any faulty components promptly.
Step 3: Inspect integrated circuits on the circuit board, such as CPUs and AD chips. Address any issues like bulging or burning promptly to ensure proper function.
In PCB circuit board prototyping, the effective and reasonable use of components is crucial for the stability and quality of the board. So, what issues should be addressed during the PCB prototyping process?
1. Limit the output current to avoid the locking effect in CMOS circuits: The locking effect refers to the presence of parasitic PNP and NPN transistors within the CMOS circuit, forming a parasitic PNPN thyristor structure. A common solution is to use a resistor to isolate each output terminal from its connecting cable and to clamp the cable with two high-speed switching diodes to VDD (drain power) and VSS (source power).
2. Implement a filter network: When a long input cable is required between the CMOS circuit system and mechanical contacts, the risk of electromagnetic interference increases. Therefore, incorporating a filter network is advisable.
3. Forming an RC Network: For sensitive inputs on bipolar devices, use an RC network consisting of a high-value resistor and a capacitor of at least 100pF to mitigate the effects of electrostatic discharge.
4. Avoid Floating Input Pins on CMOS Devices: Floating input pins can cause instability in input potential, disrupting the circuit’s logical functions and making it susceptible to electrostatic breakdown and external noise interference. Redundant input terminals should be managed according to the circuit’s design requirements.
2. Simple Maintenance Skills and Production Process of Circuit Boards
Circuit boards are also known by various names, including PCB boards, aluminum substrates, high-frequency boards, thick copper boards, impedance boards, ultra-thin circuit boards, and printed (copper etching technology) circuit boards.
Circuit Board Repair Skills: Observation Method
This intuitive method involves inspecting the board to identify burnt traces. When using this approach, consider the following:
Step 1: Determine if the circuit board has been damaged manually by checking:
(1) Deformation of the board’s corners, chips, or other components.
(2) Signs of tampering with the chip and socket.
(3) Proper insertion of the circuit board chip, as damage can occur when power is applied.
(4) Correct insertion and orientation of short-circuit terminals.
Step 2: Examine all components related to the circuit board, including capacitors and resistors, for signs of blackening. Since resistance values are not visible, use an instrument to measure them. Replace any faulty components promptly.
Step 3: Inspect integrated circuits on the circuit board, such as CPUs and AD chips. Address any issues like bulging or burning promptly to ensure proper function.
