1. Impact of Plate Hole Solderability on PCBA:
- Poor solderability of plate holes can lead to PCBA solder defects, impacting circuit component parameters and causing instability in multilayer board elements and inner lines.
- Solderability refers to the metal surface’s characteristics when wetted by molten solder, forming a uniform, continuous, smooth adhesion film.
2. Factors Affecting Solderability:
- (1) Solder Composition and Properties:
- Utilization of low melting point eutectic metals (e.g., Sn-Pb or Sn-Pb-Ag) in solder.
- Control of impurities to prevent oxides during soldering.
- Use of white rosin and isopropanol solvents for surface wetting.
- (2) Temperature and Metal Plate Surface:
- Excessive temperature accelerates solder diffusion, causing weld defects like tin beads, tin balls, and broken circuits.
- Oxygenation of the circuit board and melted solder surface can lead to defects.
3. Warping-Induced PCBA Solder Defects:
- Stress-induced deformation, often due to temperature imbalances, causes solder joint and short circuit defects.
- Large PCBs may warp under their own weight, affecting component placement and soldering.
4. PCB Design Considerations:
- In large PCBs, soldering is easier to control, but issues like increased printing line length, impedance, reduced noise resistance, and higher costs may arise.
- Tiny PCBs pose challenges in cooling and soldering control, emphasizing the need for optimization in PCB design.