Method for manufacturing electronic parts device and resin composition for electronic parts encapsulation

A method for manufacturing an electronic parts device, said method comprising:

• a step of disposing a plurality of electronic parts in an array on a package substrate, and then stacking, in order, a thermosetting resin composition sheet shown in (B) below (sheet B) and a thermosetting resin composition sheet shown in (A) below (sheet A) on an electronic parts-mounting area of the package substrate while arranging the center and XY-plane direction of the electronic parts-mounting area to substantially agree with the centers and XY-plane directions of both the sheets A and B;
• a step of heating the package substrate which holds this arrangement state at a molding temperature selected from the range of 70 to 150° C. in a chamber under reduced pressure, thereby causing an end part of an entire circumference of the sheet A to be softened and sag into contact with the package substrate and tightly closing a space surrounded by the entire circumference of the sheet A;
• a step of, in the sagged state, pressing the sheet A covering the sheet B and the electronic parts;
• a step of releasing the pressure in the chamber to perform underfilling of the electronic parts by a melt of the sheet B in the closed space formed between the sheet A and the package substrate;
• a step of, after the underfilling, thermally curing the resin compositions of both the sheets A and B to obtain an electronic parts device assembly where the plurality of electronic parts on the package substrate are resin-encapsulated;
• and
• a step of dicing the electronic parts device assembly to obtain each discrete electronic parts device;
• (A) a thermosetting resin composition sheet having a viscosity at the molding temperature of from 2,000 to 50,000 Pa·s and having a dimension satisfying the following condition (1):
• Ax>P+8
• Ay>Q+8 <Condition (1)>
• in which Ax is a length (mm) in an X-axis direction of the sheet A, Ay is an length (mm) in a Y-axis direction of the sheet A, P is a length (mm) in an X direction of the electronic parts-mounting area, and Q is a length (mm) in a Y direction of the electronic parts-mounting area,
• (B) a thermosetting resin composition sheet having a viscosity at the molding temperature of from 20 to 250 Pa·s and having a dimension satisfying the following condition (2):
• Ax≧Bx>P×0.8
• Ay≧By>Q×0.8 <Condition (2)>
• in which Bx is a length (mm) in an X-axis direction of the sheet B, By is a length (mm) in a Y-axis direction of the sheet B, P is the length (mm) in the X direction of the electronic parts-mounting area, Q is the length (mm) in the Y direction of the electronic parts-mounting area, Ax is the length (mm) in the X-axis direction of the sheet A, and Ay is the length (mm) in the Y-axis direction of the sheet A.