Creep　resistance　and　thermal　fatigue　performance　of　soldered　connections/joints　are　essential　reliability　concerns　for　microelectronic,　optoelectronic　and　photonic　packaging　systems.　In　this　study,　creep　fracture　behaviour　of　lap　shear　joints　soldered　by　a　tin-lead　based　composite　solder　reinforced　by　nano-sized　metallic　particles　and　a　lead-free　Sn-Ag-Bi　alloy　solder　was　characterized　at　different　homologous　temperatures,　with　a　comparison　to　a　traditional　Sn60Pb40　solder.　The　results　show　that　at　all　temperatures　tested　the　nanocomposite　solder　has　much　better　creep　resistance　than　Sn60Pb40　solder,　in　terms　of　the　creep　rupture　life.　The　lead-free　Sn-Ag-Bi　solder　has　superior　creep　performance　to　both　Sn60Pb40　and　nano-composite　solders.　The　creep　fractography　analysis　by　SEM　shows　that　a　progressive　shear　deformation　occurred　as　the　main　creep　fracture　mechanism.　Sn60Pb　solder　joints　deform　dominantly　by　transgranular　sliding,　while　Sn-Ag-Bi　and　nano-composite　solder　joints　creep　by　intergranular　mechanism　through　grain　boundary　sliding　and　voids　growth.　The　mechanism　of　enhancing　the　creep　resistance　of　nano-composite　solder　joints　is　that　the　nano-sized　particulates　with　a　uniform　dispersion　provide　effective　resistance　by　impeding　grain　boundary　sliding　and　dislocation　movement,　besides　the　alloying　effect　of　increasing　elasticity　modulus　of　the　solder.