A cleaning process for flip chip assemblies before encapsulation

Flip chip technology offers high I/O density on a small footprint with fast signal processes, due to the short electrical interconnect length. However, the residues of the flux-metal reaction can be entrapped underneath the chip and may be difficult to clean/remove. These residues can degrade the reliability of the flip chip assembly with corrosive effects. Since the excessive use of chlorofluorocarbons and toxic solvents for cleaning have been raising environmental issues, it is important to develop cleaning processes that are reliable and non-toxic. The surface insulation resistance (SIR) test system is proposed to measure the levels of contamination on the test coupon.