Building　upon　our　previous　database　of　the　thermal,　electrical,　and　mechanical　properties　of　commercial　REBCO　tape,　we　have　constructed　a　subsequent　database　focusing　on　the　Cu　layer　of　such　tapes　from　eight　distinct　manufacturers.　This　database　encompasses　information　pertaining　to　the　geometry,　purity,　and　grain　orientation　of　the　Cu　layer.　The　primary　objective　of　this　database　is　to　not　only　elucidate　the　material　science　of　the　Cu　layer　across　various　commercial　tapes　but　also　to　establish　correlations　between　the　thermal,　electrical,　and　mechanical　properties　and　the　aforementioned　geometry,　purity,　and　grain　orientation　parameters.　After　analysis,　three　significant　findings　have　been　validated.　Firstly,　the　non-uniformity　of　geometry　plays　a　critical　role　in　the　electrical　resistivity　in　the　radial　direction,　primarily　through　altering　the　actual　contact　surface　area.　Secondly,　it　has　been　observed　that　the　total　grain　boundary　length　per　micrometer　thickness　exhibits　a　nearly　linear　correlation　with　the　thermal　conductivity　in　the　circumferential　direction.　Thirdly,　the　purity　of　the　Cu　layer　in　all　the　commercial　REBCO　tapes　is　lower　than　anticipated.　It　is　our　aspiration　that　this　database　will　facilitate　enhanced　comprehension　of　the　Cu　layer　in　REBCO　tapes　among　a　broader　spectrum　of　researchers.