A study of Stretched Solder Column Interconnects for Ultra-Fine Pitch Flip Clip Packages

Abstract

In the first part of this work, a new solder joint interconnect, stretched solder column (SSC) is introduced. A computer code was developed to predict transient axial symmetric solder joint shape. An experiment was conducted to form the SSC joints between two chips. The simulation results show good correlation with experiment.In the second part of this work, a slim sector model was proposed and developed to study the reliability of ultra fine flip chip package. Study shows that the 1B= pitch slim sector model shows consistently high accuracy and high computational time efficiency. In the third part of this work, a solder underfill based representative volume element (RVE) is developed. The effective elasto-plastic-creep properties of the proposed equivalent homogeneous material were extracted. With the application of the RVE results, hybrid slim sector model is developed, which is the best in terms of accuracy and ease of use.