Simulation of Underfill Flowing and Curing in Flip-Chip Packaging with Extension Runner

Chao-Ming Lin, Win-Jin Chang

            Assistant Professor

Department of Electrical Engineering, WuFeng Institute of Technology,

Chia-I, Taiwan 621, Email address: cmlin@mail.wfc.edu.tw

Professor

Department of Mechanical Engineering, Kun-Shan University of Technology

Tainan, Taiwan 710.

ABSTRACT

The reliable Hele-Shaw flow model is adopted in the numerical investigation of the injection molding flip-chip packaging process. The complex 3D geometries and flow behaviors are simplified and modeled by a 2.5D thin-shell simulation. The injection molding IC packaging process involves chip packaging and encapsulation techniques comprising mainly of cavity-filling and curing processes. Important aspects of the cavity-filling process include the choice of runner type, the mold geometry, the injection process, the injection and packing pressure, and the process temperature. Curing analysis includes encapsulation, conversion and shrinkage aspects. The current investigation considers different runner types, the flow front, the pressure field, the stress field and warpage.  It is shown that the adaptive extension runner provides improved pressure and stress distribution, while minimizing warpage.