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

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

• disposing a plurality of electronic parts in an array on a package substrate, and then stacking, in order, a thermosetting resin composition sheet B and a thermosetting resin composition 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;
• 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 to cause 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;
• pressing the sheet A covering the sheet B and the electronic parts in the sagged state;
• 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;
• 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
• dicing the electronic parts device assembly to obtain each discrete electronic parts device;
• wherein, the thermosetting resin composition sheet A having a viscosity at the molding temperature of from 2,000 to 50,000 Pa·s and having a dimension satisfying the following condition I:
• Ax>P+8
• Ay>Q+8
• in which Ax is a length in an X-axis direction of the sheet A, Ay is an length in a Y-axis direction of the sheet A, P is a length in an X direction of the electronic parts-mounting area, and Q is a length in a Y direction of the electronic parts-mounting area,
• wherein, the thermosetting resin composition sheet B having a viscosity at the molding temperature of from 20 to 250 Pa·s and having a dimension satisfying the following condition II:
• Ax≧Bx>Px0.8
• Ay≧By>Qx0.8
• in which Bx is a length in an X-axis direction of the sheet B, By is a length in a Y-axis direction of the sheet B, wherein all the lengths of the sheets A and B and of the parts-mounting area are measured in millimeter (mm).