Warpage modeling technique of organic interposer considering deformation by insulator material shrinkage

Abstract

The increase of organic interposer warpage in large-die fine-pitch flip-chip package applications makes more challenging for C4 bumps on chip to be connected to solder on the interposer pads during reflow process for chip attach. Therefore the pattern layout and material selection of the interposer should be optimized to minimize the warpage during the reflow. In order to do that, it is essential to establish a precise mechanical modeling methodology to predict warpage behavior in earlier stage of design. In the typical modeling, initial warpage at final lamination process of interposer manufacturing is assumed to be zero. However the actual has some deformation caused by such as resin cure shrinkage and handling at manufacturing operations. It can't be ignored on the prediction and results in the accuracy limitation. In this paper, we focus on the warpage behavior of organic laminates consisting of glass reinforced core, build-up and solder resist materials which have been widely used for application processor of mobile applications and high-end microprocessors. Firstly, we try to characterize the cure shrinkage of build-up and solder resist materials. Then we try to make a new modeling technique for the warpage prediction simulating the actual laminate manufacturing process steps considering such material shrinkage. The results of the warpage by the new models are indicating that the technique can realize the shape of the initial warpage just after laminate manufacturing line.