Post-bond Compression Process for Bonding Thin-Die on BT Substrate using Thermoplastic Adhesive Tape

Void formation along the bonding interface of bottom die and the BT substrate by using thermalplastic tape adhesives is studied in this article. Effect of surface (i) unevenness of the substrate, (ii) size and thickness of die as well as (iii) the die bonding parameters such as time and force on the interfacial void formation have been investigated experimentally. A post-bond compression process is introduced to reduce the size and number of voids. Finite element model is built to understand the characteristics of void under compression. Both experimental results and finite element method (FEM) analysis show that higher compressive force is needed to reduce the void formation for a thicker die than for a thinner die for given tape application process - tape is applied to substrate first and then die bonding. It is due to a lower rigidity of the die can conform better to an uneven substrate