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Application of copper lead frame to plastic encapsulated VLSIs is increasing these days because of its high thermal conductivity and low cost. But there is a potential of stress induced problems such as die warpage, crack and delamination from the lead frame when a large die is bonded. These failures are caused by the thermal mismatch between silicon die and copper lead frame. die bonding technology. Stress analysis by FEM (Finite Element Method) and die bonding experiment was performed,and it was found that the die bond adhesive of very low Young's modulus is effective to reduce the thermal stress. A new silicone elastomer adhesive and in-line cure process named clean cure process were developed. Ir, this process , the adhesive is cured quickly on a heat column and volatile organic species, which affect the yield and reliability of devices are reduced significantly while being c u r d By applying this technology, bonding of large die to copper lead frame was successfully performed.

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