Method for joining lead frames in a package assembly, method for forming a chip stack package, and a chip stack package

摘要

A method for joining lead frames in a chip stack package or a package stack, a chip stack package, and a method of forming a chip stack package. A joining mediator is formed on joining portions of at least one lead frame. The joining mediator has an anti-oxidation property and an inter-metallic diffusion property, and may be formed of gold wires, gold bumps, gold bars, solder bumps, solder, or solder bars. By clamping or compressing the lead frames under heat and pressure, the joining mediator forms an inter-metallic joint layer that reliably interconnects the lead frames at the joining portions.