1. Points to Note During PCBA Processing
PCBA refers to the process where an empty PCB board undergoes SMT loading followed by DIP plug-in, collectively known as PCBA. Today, we will delve into key considerations during PCBA processing.
1. Transportation: To prevent damage to PCBA, adhere to the following packaging guidelines:
1. Container: Use anti-static turnover boxes.
2. Isolation Material: Employ anti-static pearl cotton.
3. Placement Spacing: Ensure there is a minimum of 10mm distance between the PCB board and the box, as well as between boards.
4. Placement Height: Maintain a space greater than 50mm from the top surface of the turnover box to avoid pressure on the power supply, particularly on the power supply wires.
2. PCBA Processing and Washing Requirements: The board surface should be clean and free from tin beads, component pins, and stains. It is crucial that solder joints on the plug-in surface are free of any soldering residues.
The following devices should be protected when washing the board: wires, connecting terminals, relays, switches, polyester capacitors, and other components prone to corrosion. Relays, in particular, must not be cleaned using ultrasonic methods.
**Considerations During PCBA Processing**
3. No components are allowed to extend beyond the edge of the PCB after installation.
4. When PCBA is processed through the furnace, the pins of plug-in components may be washed by the tin flow. This can cause some plug-in components to tilt after soldering, resulting in the component body extending beyond the silk screen frame. Repair welding personnel must make appropriate corrections after the tin furnace process.
1. Horizontal floating high-power resistors can be realigned once, with no restrictions on the alignment angle.
2. Horizontal floating diodes (such as DO-201AD packaged diodes) or other components with pin diameters greater than 1.2mm can be centered once, with the centering angle not exceeding 45°.
3. Vertical resistors, vertical diodes, ceramic capacitors, vertical fuses, varistors, thermistors, and semiconductors (such as TO-220, TO-92, TO-247 packages) with a component body floating height greater than 1mm can be centered once, with the centering angle not exceeding 45°. For components with a floating height less than 1mm, the solder joints must be melted with a soldering iron for realignment or replaced with new devices.
4. In PCBA processing, electrolytic capacitors, manganese copper wires, inductors with skeletons or epoxy board bases, and transformers should generally not be realigned. If necessary, soldering should be performed once. If there is any inclination, use a soldering iron to melt the solder joints before realigning, or replace the component with a new one.
**Process Requirements for SMT Patch Processing**
The process requirements for SMT patch processing and component placement dictate that components should be accurately placed on the printed circuit board according to the assembly drawing and schedule.
1. SMT Processing and Placement Requirements: The type, model, nominal value, polarity, and other characteristics of each component must match the product assembly drawing and schedule. Components must be intact. The solder ends or pins of SMT chip-mounted components must be immersed in solder paste by at least 1/2 the thickness. For general components, the amount of solder paste extrusion should be less than 0.2mm during placement; for fine-pitch components, it should be less than 0.1mm. The solder ends or pins should be aligned and centered with the land pattern. Due to the self-alignment effect of reflow soldering, some deviation is acceptable. Refer to relevant IPC standards for specific deviation ranges.
2. Three Key Elements to Ensure PCB Circuit Board Mounting Quality:
1. **Correct Components:** Ensure that the type, model, nominal value, and polarity of each component match the product assembly drawing and schedule. Components should not be misplaced.
2. **Accurate Placement:** The solder ends or pins of components should be aligned and centered with the land pattern, ensuring that they make contact with the solder paste pattern.
3. **Proper Pressure:** Placement pressure should match the Z-axis height of the nozzle. A high Z-axis height results in lower placement pressure, while a low Z-axis height results in higher placement pressure. If the Z-axis height is too high, the component may float on the solder paste, preventing proper adhesion and increasing the risk of position shifts during transmission and reflow soldering. Conversely, if the Z-axis height is too low, excessive solder paste extrusion may occur, leading to solder paste adhesion and bridging during reflow soldering. Additionally, excessive solder paste extrusion can cause component damage and misalignment. Thus, the Z-axis height of the suction nozzle must be appropriately adjusted during placement.
PCBA refers to the process where an empty PCB board undergoes SMT loading followed by DIP plug-in, collectively known as PCBA. Today, we will delve into key considerations during PCBA processing.
1. Transportation: To prevent damage to PCBA, adhere to the following packaging guidelines:
1. Container: Use anti-static turnover boxes.
2. Isolation Material: Employ anti-static pearl cotton.
3. Placement Spacing: Ensure there is a minimum of 10mm distance between the PCB board and the box, as well as between boards.
4. Placement Height: Maintain a space greater than 50mm from the top surface of the turnover box to avoid pressure on the power supply, particularly on the power supply wires.
2. PCBA Processing and Washing Requirements: The board surface should be clean and free from tin beads, component pins, and stains. It is crucial that solder joints on the plug-in surface are free of any soldering residues.
The following devices should be protected when washing the board: wires, connecting terminals, relays, switches, polyester capacitors, and other components prone to corrosion. Relays, in particular, must not be cleaned using ultrasonic methods.
**Considerations During PCBA Processing**
3. No components are allowed to extend beyond the edge of the PCB after installation.
4. When PCBA is processed through the furnace, the pins of plug-in components may be washed by the tin flow. This can cause some plug-in components to tilt after soldering, resulting in the component body extending beyond the silk screen frame. Repair welding personnel must make appropriate corrections after the tin furnace process.
1. Horizontal floating high-power resistors can be realigned once, with no restrictions on the alignment angle.
2. Horizontal floating diodes (such as DO-201AD packaged diodes) or other components with pin diameters greater than 1.2mm can be centered once, with the centering angle not exceeding 45°.
3. Vertical resistors, vertical diodes, ceramic capacitors, vertical fuses, varistors, thermistors, and semiconductors (such as TO-220, TO-92, TO-247 packages) with a component body floating height greater than 1mm can be centered once, with the centering angle not exceeding 45°. For components with a floating height less than 1mm, the solder joints must be melted with a soldering iron for realignment or replaced with new devices.
4. In PCBA processing, electrolytic capacitors, manganese copper wires, inductors with skeletons or epoxy board bases, and transformers should generally not be realigned. If necessary, soldering should be performed once. If there is any inclination, use a soldering iron to melt the solder joints before realigning, or replace the component with a new one.
**Process Requirements for SMT Patch Processing**
The process requirements for SMT patch processing and component placement dictate that components should be accurately placed on the printed circuit board according to the assembly drawing and schedule.
1. SMT Processing and Placement Requirements: The type, model, nominal value, polarity, and other characteristics of each component must match the product assembly drawing and schedule. Components must be intact. The solder ends or pins of SMT chip-mounted components must be immersed in solder paste by at least 1/2 the thickness. For general components, the amount of solder paste extrusion should be less than 0.2mm during placement; for fine-pitch components, it should be less than 0.1mm. The solder ends or pins should be aligned and centered with the land pattern. Due to the self-alignment effect of reflow soldering, some deviation is acceptable. Refer to relevant IPC standards for specific deviation ranges.
2. Three Key Elements to Ensure PCB Circuit Board Mounting Quality:
1. **Correct Components:** Ensure that the type, model, nominal value, and polarity of each component match the product assembly drawing and schedule. Components should not be misplaced.
2. **Accurate Placement:** The solder ends or pins of components should be aligned and centered with the land pattern, ensuring that they make contact with the solder paste pattern.
3. **Proper Pressure:** Placement pressure should match the Z-axis height of the nozzle. A high Z-axis height results in lower placement pressure, while a low Z-axis height results in higher placement pressure. If the Z-axis height is too high, the component may float on the solder paste, preventing proper adhesion and increasing the risk of position shifts during transmission and reflow soldering. Conversely, if the Z-axis height is too low, excessive solder paste extrusion may occur, leading to solder paste adhesion and bridging during reflow soldering. Additionally, excessive solder paste extrusion can cause component damage and misalignment. Thus, the Z-axis height of the suction nozzle must be appropriately adjusted during placement.