Gold Embrittlement Mitigation

Gold embrittlement in SnPb solder is a well-known failure mechanism in electronic assembly. Voiding in SMT solder joints & Gold plated components dislodging from the PCB are two well-known failure modes of Gold Embrittlement.

BGA Test and Technology has developed a Robotic Process which uses SnPb alloy dynamic solder wave for gold removal.

IPC-J-STD-001 criterion 4.5.1 — Gold Removal

Gold Shall Be Removed: N1P2D3

• ▸From at least 95% of the surfaces to be soldered of the Through-hole component leads with 2.54 μm or more of gold thickness.
• ▸From 95% of all surfaces to be soldered of Surface mount components regardless of gold thickness.
• ▸From the surfaces to be soldered of Solder terminals plated with 2.54 μm or more of gold thickness.
• ▸Scanning Electron Microscope (SEM) — Post-Ball Shear Analysis
• ▸Cleanliness — Ionic Contamination Analysis
• ▸Electrical Testing (Pre & Post Re-balling)

A double tinning process or dynamic solder wave may be used for gold removal prior to soldering the component in the assembly.