ACA Curing Process Optimization Based on Curing Degree Considering Shear Strength of Joints

Guanghua Wu,Michael Pecht,Diganta Das,Meixian Jiang

doi:10.1109/access.2019.2959324

Abstract

This paper presents an optimized curing process for the shear strength achievement and retention for anisotropic conductive adhesive (ACA) flip-chip interconnections. The curing kinetics of ACA is first presented and then a curing degree $(\alpha)$ relationship between curing temperature $T$ and curing time $t$ is established. The influence of different curing degree states on the interfacial shear strength is then reported, including the effect of degree of curing on shear strength both before and after hygro-thermal aging.

Highlights

Anisotropic conductive adhesive (ACA) has numerous advantages—it is environmentally friendly and lead-free, has a lower packaging temperature, and results in reduced thickness
F (α) is the curing kinetic model, and k(T ) is the temperature-dependent rate constant given by the Arrhenius equation as k = A · exp(−E (R · T ))
The curing kinetics of the ACA was investigated by experiments, and the curing kinetics equation for curing degree α, curing temperature T, and curing time t was established for various ACAs

Summary

Introduction

Anisotropic conductive adhesive (ACA) has numerous advantages—it is environmentally friendly and lead-free, has a lower packaging temperature, and results in reduced thickness. It is used in many electronic packaging interconnect products, such as flip-chip bonding of radio frequency identification (RFID) inlays, chip-on-glass (COG) packaging for liquid crystal displays (LCDs), and chip-in-flex packages for wearable electronics [1]–[4]. The ACA bonding process has three different parameters: bonding time, bonding temperature, and bonding pressure. These bonding parameters influence the contact resistance of ACA joints and greatly determine their adhesive strength. Among them, bonding time and bonding temperature have a significant influence on the bonding shear strength, whereas bonding pressure influences the electrical resistance

Methods

Results

Conclusion