Based　on　environmental　considerations,　global　economic　pressures,　enacted　by　legislations　in　several　countries,　have　warranted　the　elimination　of　lead　from　solders　used　in　electronic　applications.　Sn3.5Ag,　SnAgCu,　and　Sn0.7CU　have　emerged　among　various　lead-free　candidates　as　the　most　promising　solder　alloys　to　be　utilized　in　microelectronic　industries.　However,　with　the　vast　development　and　miniaturization　of　modern　electronic　packaging,　new　requirements　such　as　superior　service　capabilities　have　been　posed　on　lead-free　solders.　In　order　to　improve　the　comprehensive　property　of　the　solder　alloys,　two　possible　approaches　were　adopted　in　the　current　research　and　new　materials　developed　were　patented.　One　approach　was　involved　with　the　addition　of　alloying　elements　to　make　new　ternary　or　quaternary　solder　alloys.　Proper　addition　of　rare　earth　element　such　as　La　and　Cc　have　rendered　solder　alloys　with　improved　mechanical　properties,　especially　creep　rupture　lives　of　their　joints.　Another　approach,　the　composite　approach,　was　developed　mainly　to　improve　the　service　temperature　capability　of　the　solder　alloys.　Composite　solders　fabricated　by　mechanically　incorporating　various　reinforcement　particles　to　the　solder　paste　have　again　exhibited　enhanced　properties　without　altering　the　existing　processing　characteristics.　The　recent　progress　and　research　efforts　carried　out　on　lead-free　solder　materials　in　Beijing　University　of　Technology　were　reported.　The　effects　of　rare　earth　addition　on　the　microstructure,　processing　properties,　and　mechanical　properties　were　presented.　The　behaviors　of　various　Sn-3.5Ag　based　composite　solders　were　also　explicated　in　terms　of　the　roles　of　reinforcement　particles　on　intermetallic　growth,　steady-state　creep　rate,　the　onset　of　tertiary　creep,　as　well　as　the　overall　creep　deformation　in　the　solder　joints.　Thermomechanical　fatigue　(TMF)　behavior　of　the　solder　alloys　and　composite　solders　were　investigated　with　different　parameters　such　as　ramp　rate,　dwell　time,　etc.　The　damage　accumulation　features　and　residual　mechanical　properties　of　the　thermomechanicallyfatigued　composite　solder　joints　were　compared　with　non-composite　solder　joints.　To　match　the　lead-free　alloys,　various　types　of　water　soluble　no-clean　soldering　flux　have　also　been　developed　and　their　properties　were　presented.