Although　all　the　commercial　REBCO　tapes　claim　the　stabilizer　layer　is　pure　Cu,　the　turn-to-turn　contact　resistance　of　coils　wound　from　conductors　sourced　from　different　manufacturers　may　have　a　difference　of　more　than　an　order　of　magnitude.　The　Cu　layer　in　the　REBCO　tape　with　high　contact　resistance　has　a　less　dense　microstructure　and　a　higher　impurity　chemical　compound　such　as　oxide　and　carbide　after　systematically　investigating.　Such　a　phenomenon　can　reveal　a　possible　new　partial　insulation　strategy　that　the　contact　resistance　could　be　increased　without　further　co-winded　with　other　materials　by　adjusting　the　microstructure　and　chemical　composition　in　the　Cu　layer.　Increasing　the　contact　resistance　with　no　co-winded　with　other　materials　will　decrease　the　charging　decay　rate　and　not　sacrifice　the　Je　value,　which　has　application　potential　in　the　extremely　high　field　superconducting　magnets.