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Stress evaluation of flip chip bonding die by thermal compression bonding using Raman spectroscopy

We evaluated the residual stress of the Si die which bonding to organic substrate by the flip chip technology, using Raman spectroscopy. Non-conductive paste (NCP) and non-conductive film (NCF) are used for the high-density flip chip joint as pre applied underfill. Then, it was understand that a physical characteristic of NCF influenced the residual stress of the Si die. In the NCF part of the die corner part, correlation was accepted by the coefficient of thermal expansion (CTE) and residual stress of NCF. On the other hand, in the NCF + solder resist (SR) part, NCF relieved stress by the shrinkage of the SR. It was explained that resin of NCF is a low coefficient of elasticity. In addition, it was shown that residual stress was low in the circumference of Cu pillar by the pinning effect.