Plastic encapsulated integrated circuit of copper wire will be made and improved more popularly in the development of high speed integrated circuit for its low price and performance advantages. In the Destructive Physical Analysis(DPA), a lot of this type of integrated circuit will be encountered, which will lead to corrosion problems on copper wire and bonding points during decapsulation. The proper decapsulation method is as follows: after laser decapsulation，using mixed acid to erode plastic can keep the copper wire and bonding points well without plastic residual on the surface of chip. The experiments provide a reliable way to decapsulate integrated circuit of copper wire.