Definition
A method of soldering aluminum and other hard-to-solder metals in which the molten solder is agitated with high-frequency sound waves. The vibrations break up the tough oxide film on the metal surface, allowing the solder to wet and bond directly to the base metal without the use of chemical flux.
Plain English
A way of soldering aluminum by shaking the melted solder with sound waves. The shaking scrubs off the thin invisible coating on the metal so the solder can stick, without needing the usual cleaning chemicals.
Context Anchor
Seen in aircraft maintenance and repair discussions, especially when joining or repairing metal parts that do not accept ordinary solder easily.
Derivation
Sonic comes from the Latin sonus meaning sound. The name reflects the use of sound-wave vibration as the working tool of the process, instead of a chemical flux.
Why Pilots Care
A soldered joint on an aircraft must be made by the correct method for the material. Poor soldering can create a weak or unreliable repair, which can affect airworthiness.
Intuition Check
Sonic soldering does not mean the sound itself melts the solder. Heat melts the solder; the sound vibration helps the solder bond to a surface that would otherwise resist it.
Example Sentence 1
The technician used sonic soldering to attach a fitting to the aluminum fuel line, since standard flux would not have produced a clean bond.
Example Sentence 2
Sonic soldering allowed the repair to proceed without using corrosive flux on the thin wing spar.