Reliability Prediction and Improvement of Board-Level Thermal Cycling Test for Molded Flip-Chip Ball-Grid-Array Package

The study focused on the Board-Level Thermal Cycling Test (BL-TCT) reliability of the Molded Flip-Chip Ball-Grid-Array (MFCBGA) package. The Anand viscoplastic model was used to describe the plastic and creep behaviors of the solder material. The lifecycle prediction model with Morrow’s energy based method was used to fit a number of data points and the deviation of characteristic lifecycle can be predicted within ±15%. Furthermore, the parametric studies were conducted to enhance the lifecycle of MFCBGA series.

Introduction

Accelerated reliability tests are usually implemented to understand the operating lives of a product under different environment conditions. These tests can be classified to the Package-Level (PL) and Board-Level (BL) reliabilities. The PL tests consider the environment factors include the pressure, the temperature, the humidity, the voltage. The related tests are the Pressure Cooker Test (PCT) [1], the Temperature Cycling Test (TCT) [2], the High Temperature Storage Test (HTST) [3], the biased Highly-Accelerated Stress Test (HAST or bHAST [4], where the stress means the higher temperature and higher humidity), and the un-biased Highly-Accelerated Stress Test (uHAST) [5]. On the other hand, the BL tests consider the package mounted on a Print Circuit Board (PCB) under the more practical situations such as TCT (turn on/off) [2], vibration (transportation or operating fan on CPU) [6], drop (dropping of a cell phone) [7], and so on.