The　sintering　process　of　Cu　nanoparticles　is　challenging　due　to　the　oxidation　of　Cu　and　the　formation　of　voids　in　the　die-attach　layer.　In　this　work,　a　simple　and　cost-effective　bimodal-sized　Cu　composite　paste　was　prepared　for　a　high-strength　Cu-Cu　joint.　The　joint　microstructure　and　sintering　properties　were　systematically　investigated　by　adjusting　the　mass　ratio　of　the　particle　dimensions　from　80　nm　to　300　nm　and　varying　the　sintering　parameters.　Die　attachment　by　pressure　(20　MPa)-assisted　sintering　in　air　at　250　degrees　C　was　rapidly　achieved　using　bimodal-sized　Cu　particles.　The　joint　sintered　for　1　min　exhibited　shear　strength　of　85.63　MPa,　while　5-min　sintering　was　able　to　obtain　a　dense　bondline　structure,　and　the　shear　strength　reached　102.46　MPa.　The　sintered　layers　in　nitrogen　had　the　highest　thermal　conductivity　of　284　W/m　K　and　low　resistivity　of　4.42　mu　ohm　cm.　These　results　confirm　that　bimodal-sized　Cu　composite　paste　can　be　considered　as　an　inexpensive　potential　die-attach　material　for　high-temperature　electronics　packaging.