Bonding sheet with preform layer, method for manufacturing bonded body, and to-be-bonded member with preform layer

A method for manufacturing a bonded body, comprising:

• a step of preparing a substrate and an electronic component which are to be bonded to each other, in which either one or both of a bonding surface of the substrate and a bonding surface of the electronic component are each a copper surface or a nickel surface;
• a step of forming a porous preform layer on one or both of the bonding surfaces;
• a step of laminating the substrate and the electronic component in a state where one or two of the porous preform layers are interposed between the substrate and the electronic component to obtain a laminate;
• and
• a step of heating the laminate in a state of being pressurized in a lamination direction to obtain a bonded body, wherein the porous preform layer is not sintered before the step of heating,
• wherein the porous preform layer includes copper particles,
• surfaces of the copper particles are coated with copper nanoparticles having an average particle diameter smaller than an average particle diameter of the copper particles, the average particle diameter of the copper nanoparticles calculated from a BET value is 61.8 nm or more and 850 nm or less,
• an average porosity of the porous preform layer is 11% or more and 78% or less, and
• the average porosity of the porous preform layer is an arithmetic average of a porosity (P) obtained by the following Expression (1), based on a total area (S1) of the porous preform layer and an area (S2) of a pore portion in the porous preform layer, both of which are calculated by image analysis of a cross section of the porous preform layer with a scanning electron microscope,
• P(%)=(S2/S1)×100 (1).

A to-be-bonded member with a porous preform layer, which is either one of an electronic component or a substrate to be bonded to each other, the to-be-bonded member comprising:

• a copper surface or a nickel surface;
• and
• the porous preform layer provided on the copper surface or the nickel surface,
• wherein the porous preform layer includes copper particles,
• surfaces of the copper particles are coated with copper nanoparticles having an average particle diameter smaller than an average particle diameter of the copper particles, the average particle diameter of the copper nanoparticles calculated from a BET value is 61.8 nm or more and 850 nm or less,
• an average porosity of the porous preform layer is 11% or more and 78% or less,
• the average porosity of the porous preform layer is an arithmetic average of a porosity (P) obtained by the following Expression (1), based on a total area (S1) of the porous preform layer and an area (S2) of a pore portion in the porous preform layer, both of which are calculated by image analysis of a cross section of the porous preform layer with a scanning electron microscope,
• P(%)=(S2/S1)×100 (1),
• and
• to-be-bonded member includes the porous preform layer and either one of the electronic component or the substrate.