Common Process Issues in Reflow Soldering

Common Process Issues in Reflow Soldering

Several process issues encountered during reflow soldering may each impact product quality and reliability.

(1) Cold solder joints, incomplete soldering, or false soldering (19.25%)

Inadequate temperature settings failing to reach the minimum required soldering temperature;

Insufficient soldering time preventing full component melting;

Contaminated or oxidised pads impairing soldering effectiveness.

(2) Residual blackened solder joints and severe misaligned bubbles, accounting for 15.93%

Excessively rapid cooling post-soldering prevents internal gases from escaping;

Excessive impurities in solder compromise joint quality;

Gas contamination during the soldering process.

(3) Chip component cold solder joints, tombstoning, solder balls, accounting for 15.27%

Unreasonable component layout causing uneven heating;

Improper pad design, such as mismatched dimensions or excessive spacing;

Solder splatter occurring during the soldering process.

(4) BGA soldering defects, accounting for 12.83%

Uneven gaps between BGA ball grid array components and pads;

Solder failing to fully cover all solder balls;

Thermal stress during soldering.

(5) Component detachment and solder cracking, accounting for 10.40%

Insufficient bonding strength between components and pads;

Thermal stress during soldering causing component detachment or solder joint cracking.

(6) Connector soldering defects, accounting for 7.52%; QFN soldering defects, accounting for 7.30%

Inaccurate alignment between connector or QFN component pins and pads;

Contamination or oxides present during soldering.

(7) Missing or stray components, accounting for 4.65%; sporadic solder joint discolouration, accounting for 2.88%; severe misalignment, accounting for 2.43%

External force interference during component placement;

Unstable soldering parameters or equipment malfunction.

Issues such as poor flux volatilisation, oxygen content control, BGA melt cracking during mixed soldering, insufficient thermal compensation, and substandard rosin were also frequently mentioned.

In summary, reflow soldering process issues require comprehensive consideration of multiple factors, including equipment, materials, processes, and environmental conditions. Through continuous optimisation and adjustment, soldering quality and product reliability can be significantly enhanced.