In　this　work,　a　multiscale　coralloid　nano-Cu3Sn　composed　of　a　bimodal　structure　(~55　and　~120　nm)　has　been　successfully　synthesized　to　meet　low-cost　and　Pb-free　packaging　demands　for　high-power　electronic　application.　Owing　to　the　excellent　oxidation　resistance　of　the　Cu3Sn　intermetallic　compounds　(IMCs)　and　the　protection　of　solvent　poly(ethylene　glycol)-400　(PEG-400)　at　high　temperature,　the　full-Cu3Sn　joints　sintered　in　air　have　a　comparative　shear　strength　with　the　joints　acquired　in　vacuum　when　the　sintering　temperature　is　no　more　than　300　?.　The　full-Cu3Sn　joints　acquired　at　300　?　in　air　achieve　a　high　bonding　strength　of　40.4　MPa,　which　is　superior　to　those　of　traditional　Sn-based　solder　joints　(19　MPa)　and　fullCu6Sn5　joints　(17.7　MPa).　The　electrical　resistivity　of　the　sintered　Cu3Sn　films　reaches　29.1　mu　omega　&　BULL;cm　in　air.　Cu3.02Sn0.98　is　formed　at　the　interface　between　the　Cu　substrate　and　sintered　Cu3Sn　layer,　contributing　to　the　exceptional　bonding　strength　of　the　full-Cu3Sn　joints.　The　bonding　strength　of　the　joints　after　high-temperature　storage　(HTS)　tests　reveals　that　the　prepared　full-Cu3Sn　joints　possess　outstanding　long-term　thermal　stability　with　a　shear　strength　of　47.9　MPa　after　800　h　of　storage　at　250　?.　Our　work　breaks　through　the　synthesis　bottleneck　of　nano-Cu3Sn　IMCs　and　provides　the　underlying　insights　needed　to　guide　the　design　of　highly　stable　full-IMC　joints　for　high-temperature　electronic　packaging.