Meaning

verb solder together by using hard solder with a high melting point

origin1580s, "to expose to the action of fire", perhaps from French braser (“to solder, weld”), though the sense evolution is difficult to explain. Perhaps the English word is older, being unrecorded in Middle English but borrowed from Old French braser (“to burn”), which fits the meaning more closely. Old French braser derives from Old Norse brasa (“to braze, harden with fire”). Also possible is that…

Etymology from Wiktionary, CC BY-SA 3.0