Gold Coating in FR4-PCB Welding: Effects and Solutions

Gold has become a popular choice for surface coating in FR4-PCB welding due to its stability and reliability. However, excessive gold content can lead to the formation of brittle intermetallic compounds, affecting solder ductility. To maintain mechanical properties, it’s crucial to control the gold concentration within solder joints.

Effects of Gold Concentration:

• Excessive gold can weaken solder joints and impact bell hole formation.
• Altering base metal composition can reduce intermetallic compound formation.

Cold Welding Issues:

Cold welding, caused by incomplete reflow, results in irregular solder joints. Factors contributing to cold welding include insufficient peak temperature during reflow and inadequate time above the liquidus.

Preventing Cold Welding:

• Ensure proper reflow temperature and time.
• Address surface contamination to enhance flux activity.
• Implement post-electroplating cleaning to remove pollution residue.