| 摘要 |
PURPOSE: To enhance heat dissipation while reducing the cost by placing an IC chip in a through hole and arranging solder bumps for heat dissipation on the lower surface of the IC chip. CONSTITUTION: A through hole 50, larger than the diameter of an IC chip 9, is made in a resin board 1 and the IC chip 9 is placed directly in the through hole 50. Solder bumps 13 for heat dissipation are formed directly on the rear of the IC chip. A silver paste layer 20 is applied in order to enhance adhesion between the rear of the IC chip 9 and the solder bumps 13 and a resist film 21 serves to form the solder bumps 13 and to proof a circuit board 7 against moisture. Each pad electrode 3 is applied to the lower surface of the circuit board 7 and the heat resistant resist film 21 having circular windows is applied to the solder bump forming part of the IC chip 9. Subsequently, a solder ball is fed to each window of the resist film 21 and heat treated to form the solder bump 13 thus completing a PBGA 150. |
