What problems will PCB encounter during the mounting process？

1. Solder Joint Issues

• Problem: Cold joints, short circuits, open circuits, or pad lifting.
• Causes: Incorrect soldering temperature, insufficient/ excessive solder, oxidized components.
• Solutions:
  • Use temperature-controlled soldering tools.
  • Clean pads and component leads with alcohol before soldering.
  • Apply solder quickly (≤3 seconds) to avoid overheating.

2. Component Damage

• Problem: Burned or non-functional components.
• Causes: Electrostatic discharge (ESD), excessive heat, voltage surges.
• Solutions:
  • Use anti-static equipment (e.g., wrist straps).
  • Solder heat-sensitive components (e.g., ICs) first.
  • Verify power supply compatibility.

3. Misalignment/Displacement

• Problem: Components not aligned with solder pads.
• Causes: Poor pick-and-place accuracy or manual handling errors.
• Solutions:
  • Calibrate automated placement machines.
  • Use tweezers to align components during manual soldering.

4. Shorts/Opens

• Problem: Unintended connections or disconnected paths.
• Causes: Excess solder, bent leads, or tight pad spacing.
• Solutions:
  • Remove excess solder with desoldering braid.
  • Straighten component leads before soldering.

5. Pad Lifting

• Problem: Copper pads peeling off the PCB.
• Causes: Overheating, repeated soldering, or low-quality PCB materials.
• Solutions:
  • Limit soldering time and temperature.
  • Use high-temperature PCB materials (e.g., FR4).

6. ESD Damage

• Problem: Sudden failure of sensitive components (e.g., CMOS chips).
• Causes: Static electricity discharge during handling.
• Solutions:
  • Ground equipment and workstations.
  • Store components in anti-static packaging.

7. Thermal Issues

• Problem: Overheating of high-power components (e.g., MOSFETs).
• Causes: Inadequate heat dissipation design.
• Solutions:
  • Add heat sinks or thermal vias.
  • Optimize PCB layout for airflow.

8. Component Compatibility

• Problem: Functional failures due to mismatched components.
• Causes: Incorrect part selection or substitution errors.
• Solutions:
  • Cross-verify component specifications (e.g., resistance, voltage ratings).
  • Test components with a multimeter before installation.

9. Contamination

• Problem: Residues causing corrosion or short circuits.
• Causes: Flux or debris left on the PCB.
• Solutions:
  • Clean PCBs with isopropyl alcohol or flux remover.
  • Use no-clean flux for minimal residue.

Key Recommendations

• Design for Manufacturability (DFM): Ensure clear pad spacing and thermal reliefs during PCB design.
• Process Control: Follow standardized soldering procedures and maintain tools (e.g., clean soldering tips).
• Post-Mount Testing: Use automated optical inspection (AOI) or flying probe testers to verify connectivity.