Purpose　This　study　aims　to　investigate　the　effect　of　ultrasound　on　interfacial　microstructures　and　growth　kinetics　of　intermetallic　compounds　(IMCs)　at　different　temperatures.　Design/methodology/approach　To　investigate　the　effect　of　ultrasound　on　IMCs　growth　quantitatively,　the　cross-sectional　area　of　IMCs　layers　over　a　confirmed　length　was　obtained　for　calculating　the　thickness　of　the　IMCs　layer.　Findings　The　generation　of　dimensional　difference　in　normal　direction　between　Cu6Sn5　and　its　adjacent　Cu6Sn5,　formation　of　bossed　Cu6Sn5　and　non-interfacial　Cu6Sn5　in　ultrasonic　solder　joints　made　the　interfacial　Cu6Sn5　layer　present　a　non-scallop-like　morphology　different　from　that　of　traditional　solder　joints.　At　260　degrees　C　and　290　degrees　C,　the　Cu3Sn　layer　presented　a　wave-like　shape.　In　contrast,　at　320　degrees　C,　the　Cu3Sn　in　ultrasonic　solder　joints　consisted　of　non-interfacial　Cu3Sn　and　interfacial　Cu3Sn　with　a　branch-like　shape.　The　Cu6Sn5/Cu3Sn　boundary　and　Cu3Sn/Cu　interface　presented　a　sawtooth-like　shape　under　the　effect　of　ultrasound.　The　predominant　mechanism　of　ultrasonic-assisted　growth　of　Cu6Sn5　growth　at　260　degrees　C,　290　degrees　C　and　320　degrees　C　involved　the　grain　boundary　diffusion　accompanied　by　grain　coarsening.　The　Cu3Sn　growth　was　controlled　by　volume　diffusion　during　the　ultrasonic　soldering　process　at　260　degrees　C　and　290　degrees　C.　The　diffusion　mechanism　of　Cu3Sn　growth　transformed　to　grain　boundary　diffusion　accompanied　by　grain　coarsening　when　the　ultrasonic　soldering　temperature　was　increased　to　320　degrees　C.　Originality/value　The　microstructural　evolution　and　growth　kinetics　of　IMCs　in　ultrasonically　prepared　ultrasonic　solder　joints　at　different　temperatures　have　rarely　been　reported　in　previous　studies.　In　this　study,　the　effect　of　ultrasound　on　microstructural　evolution　and　growth　kinetics　of　IMCs　was　systematically　investigated.