In the various online sources that I’ve consulted (none of which are academic) the Franchini surname is treated as one of a group of names beginning with “Franc” (e.g. Franchetti(o), Franchi, Franchina(o), Francucci and Francuccio). The suffix is hundreds of years old and is believed to mean “of the Franks”. It exists in several forms including the Latin (Francus), the German (Frank) or French (Franco).
The earliest mention of our Franchini surname is in some notarial documents from Avio (Trento) dated 1565. Nowadays, the Franchini surname is particularly concentrated in the Emilia Romagna region of Italy where my husband’s line originated.