Factors Affecting Soldering Quality

• Solder Paste Selection

  Choosing the right solder paste is crucial for quality soldering:

  • Metal Content: Higher metal content improves viscosity and resistance to preheating forces, reducing solder bead formation.
  • Oxidation Degree: Keep solder oxidation below 0.05% to prevent solderability issues and tin bead occurrence.
  • Particle Size: Finer particles can increase oxidation and solder bead formation.
  • Flux Amount and Activity: Balance flux levels to avoid paste collapse and tin bead generation.
  • Precautions: Factors like moisture, PCB conditions, and stirring time can promote tin bead formation.

• Steel Mesh Handling

  Proper steel mesh handling is essential:

  • Opening Size: Adjust stencil openings to prevent paste spillage and solder bead occurrence.
  • Thickness: Use a stencil thickness of 0.12-0.17mm to avoid paste collapse and tin bead formation.

• Placement Machine Pressure

  Control placement pressure to prevent solder bead formation:

  Reduce mounting pressure and use suitable stencil openings to avoid paste spillage.

• Furnace Temperature Curve

  Optimize furnace temperature settings:

  Control temperature rise during preheating to prevent solder splash and tin bead formation during reflow soldering.