Copper (Cu) pillar is an inter-connection technology that provides better electrical and thermal conductivity, as compared to solder bumps, for devices with high density connections or handling higher electric current.

The advantages of Cu pillar bump are as below:
  • Better electrical performance (Good EM)
  • Better thermal fatigue performance
  • Higher elastic modulus
  • Good Reliability test result
  • Larger spacing between adjacent bumps for signal routing and easier underfill flow
  • Lower cost

ChipMOS provides Cu pillar with PI, RDL or without PI structures for customers. The min. pitch/diameter of Cu pillar could be 40um/20um.