Causes of Excessive Solder:
- Low soldering temperature leading to increased viscosity of the molten solder.
- Low preheating of the PCB, causing heat absorption by components and the PCB, resulting in a decrease in actual soldering temperature.
- Poor activity or insufficient proportion of flux, causing solder to concentrate in one area without spreading.
- Poor solderability of pads, plated through-holes, or pins, preventing sufficient wetting and trapping air bubbles in the solder joint.
- Reduction in the proportion of tin or increase in copper content in the solder alloy, leading to increased viscosity and decreased fluidity of the solder.
- Excessive solder dross leading to solder alloy encapsulating dross residue, which accumulates at the solder joint, causing it to enlarge.
Improvement Measures for Excessive Solder:
- Adjusting and selecting appropriate peak soldering temperature and soldering time.
- Setting preheating temperature based on PCB size, number of layers, quantity of components, presence of surface-mounted components, etc.
- Changing flux or adjusting its proportion appropriately.
- Improving the processing quality of PCBs, implementing a first-in-first-out component handling policy, and avoiding storage in humid environments.
- Adjusting the alloy composition of solder.
- Cleaning solder dross at the end of each shift.
