A Quick Methodology for Identifying Material Selection for Warpage Control in Backend

Previous studies on the topic of warpage control during backend manufacturing have highlighted that controlling warpage is a challenge that needs to be tackled in early design stage. Failure to do so may result in later manufacturability or reliability issues. Past studies have described a scientific approach of accurately predicting warpage behavior of molded packages. The methodologies presented, in particular the so called shrinkage method, provide a precise method of predicting warpage behavior. This is particularly useful in the design for reliability and manufacturing approach and due to its' accuracy could be very useful in the design for performance approach where packaging stresses can have substantial influence on the device performance. Previously described methodologies require characterization techniques which despite being relatively simple compared to traditional material characterization test setups still require dedicated tooling to produce samples and give the required thermal treatments to the samples. This may not always be feasible due to lack of accessibility to dedicated molds. In this paper a quick method will be explained to outline a methodology that despite being less accurate than the shrinkage method can help in taking quick decisions when faced with warpage issues in backend and where extreme precision is not needed. This method may be applicable to manufacturing of large area molded parts but may not be applicable in studying stresses or deformations in small devices especially in cases where deformation of device is affecting performance and where the scope is to study device performance.