Method for producing electronic component device and laminated film used therefor

A method for producing an electronic component device, the method comprising, in the following order:

• preparing a composite substrate which includes a support, a temporary fixing material layer, and a curable adhesive layer laminated in this order;
• disposing a plurality of electronic components on the adhesive layer of the composite substrate with a connection part in contact with the adhesive layer interposed between the adhesive layer and the electronic components;
• fixing the plurality of electronic components to the composite substrate by curing the adhesive layer;
• forming a sealing layer sealing the electronic components on the adhesive layer;
• curing the sealing layer;
• obtaining a sealed structure having the adhesive layer, the electronic components, and the sealing layer by peeling off the temporary fixing material layer from the adhesive layer;
• and
• forming a circuit surface, the sealing layer and the connection part being exposed on the circuit surface, by grinding the sealed structure from the adhesive layer side, wherein
• the plurality of electronic components include an IC chip and a chip-type passive component,
• the IC chip has a main body part and a bump provided on one main surface side of the main body part,
• the IC chip is disposed on the adhesive layer in a direction in which the bump as the connection part is in contact with the adhesive layer, and
• the passive component is disposed on the adhesive layer by a method including in the following order:
• disposing a conductor precursor for pattern formation as the connection part on the adhesive layer;
• placing the passive component on the conductor precursor;
• and
• forming a conductive pattern as the connection part by heating the conductor precursor.