A novel chip replacement method for encapsulated flip chip bonding

In FCA (Flip Chip Attach) technology, the encapsulation for the flip chip joints relieves the stress which is supposed to be concentrated on these joints by the thermal cycling of the system. It allows us to use low cost-material such as epoxy for a carrier of flip chip bonding though it has significantly higher CTE than ceramic. However, the chip replacement after encapsulation becomes difficult when it is found to be defective. To resolve this problem, we have developed a simple replacement technique. In this technique, the encapsulated chip for replacement is ground off with about a half height of encapsulation. After providing carrier bumps with solder injection, a new chip is placed and the joining cycle is followed with the same manner of initial chip join. The reliability of the joints showed the same level as the initially built joints. This technique can be applied for the replacement of any kind of encapsulated flip chip bonding