Abstract: This acidic electrolytic copper plating solution contains a soluble copper salt, an azole compound which has 2 or 3 nitrogen atoms in a five-membered ring and serves as a copper ion electrodeposition inhibitor, an acid, and water, in which a copper concentration is 0.1 mol/L or more, an azole compound concentration is 10 mmol/L or more and 50 mmol/L or less, and a chloride ion concentration is 10 ppm or less.

Abstract: This bonding sheet (10, 20) with a preform layer (13) is a bonding sheet (10, 20) for bonding a substrate (16) and an electronic component (17), the bonding sheet (10, 20) includes a copper sheet (11) and a porous preform layer (13) including copper particles (12) provided on one surface or both surfaces of the copper sheet (11), in which surfaces of the copper particles (12) are coated with copper nanoparticles (12a) having an average particle diameter smaller than an average particle diameter of the copper particles (12), the average particle diameter of the copper nanoparticles (12a) calculated from a BET value is 9.59 nm or more and 850 nm or less, and an average porosity of the preform layer (13) is 11% or more and 78% or less.