|Eutectic die attach AuSn or AuSi preforms or die with back side gold plating are not recommended for plastic open cavity packages.
Eutectic die attach methods require exposing the die and die attach pad (paddle) to temperature range of 310°C ~ 350°C. Such temperatures will cause damage to plastic open cavity QFN packages.
Eutectic die attach using AuSn or AuSi preforms are commonly used with ceramic, glass or metal packages.
Open cavity QFN packages can safely be exposed to temperatures as high as 240°C for 1 minute, typical of reflow temperatures used with RoHS alloys such as SAC305.
Open cavity plastic packages exposed to temperatures over 300°C, might experience failure mechanisms such as delamination of the mold compound from the metal leadframe, warping or distortion of the package. In extreme cases, decomposition of the molding compound may result.
Please visit Die Attach Adhesives for recommendation of attaching the die using epoxy adhesives engineered for that purpose.
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