Development of 0.45 mm thick Ultra-Thin Small Outline Package (UTSOP)

The authors developed an Ultra-Thin Small Outline Package (UTSOP) with a package thickness of 0.45 mm. In spite of the fact that it is a significant reduction relative to conventional TSOPs (1.0 mm thick), the inner leads of the lead frame can be bonded to the electrodes on the chip with gold wire as with a conventional plastic package. It is feasible since the lead that supports the chip through insulating tape (support lead) is placed on the top side of the chip. Establishing molding technology and overcoming problems such as warping of the package or chip during assembly were key points in the development of the UTSOP. The UTSOP retains the same level of reliability as a TSOP