Micro/mini-channel　heat　sinks　play　a　crucial　role　in　the　heat　dissipation　of　electronic　components,　such　as　server　chips.　In　this　study,　the　minichannel　heat　sinks　were　designed　by　6061-aluminum　alloy　to　investigate　their　heat　dissipation　capabilities.　Flow　boiling　experiments　with　low　flow　velocities　in　minichannels　were　conducted　in　the　smooth　parallel　minichannel　(SPMC)　and　porous　parallel　minichannel　(PPMC)　heat　sinks　at　conditions　of　high　power　and　low　heat　flux.　The　mass　fluxes　varied　from　121.0　to　241.9　kg/(m2s),　and　the　effective　heat　fluxes　varied　from　0　to　9.1　W/cm2.　The　effects　of　mass　flux,　heat　flux,　inlet　temperature,　and　surface　structure　on　heat　transfer　and　flow　pattern　transition　during　flow　boiling　of　HFE-7100　were　discussed.　The　research　indicates　that　at　the　room-temperature　condition,　the　maximum　decrease　in　wall　temperature　is　2.39　%　between　them　under　a　mass　flux　is　181.4　kg/(m2s)　and　a　heat　flux　is　about　7　W/cm2.　The　wall　temperature　can　be　maintained　below　75　degrees　C,　while　the　pressure　drop　is　consistently　below　0.6　kPa　at　all　conditions.　With　the　increase　in　effective　heat　fluxes,　the　boundary　of　flow　pattern　transition　becomes　less　distinct,　slug　flow　and　churn　flow　are　the　main　flow　patterns　in　the　mid/downstream　of　minichannels.