Abstract: A multi-chip stack package does not include a die pad. The elimination of the die pad provides more room for elements in the package which. Thus, a balanced inner package structure can be achieved, and a poor molding which may expose one of the package elements can be avoided. In the package, an upper chip is bonded to the top surface of a lower chip. To stabilize the chips, auxiliary or inner leads of a lead frame attach to the top surface of a lower chip. This shortens wire lengths between the chips and the inner leads. The shorter wires reduce wire loop heights and thus reduce the probability of exposing wires in a subsequent transfer-molding. A multi-chip stack package which includes an auxiliary lead(s) is also disclosed. The auxiliary leads attach to the top surface of the lower chip and can provide a stable support of a semiconductor chip and prevent the chip from tilting and shifting in transfer-molding. An auxiliary lead can be between the lower and upper chips.