Curing kinetics of anisotropic conductive adhesive film

Abstract

Polymer-based conductive-adhesive materials have become widely used in many electronic packaging interconnect applications, such as chip-on-glass, chip-on-flex, etc. Among all the conductive-adhesive materials, anisotropic conductive adhesive film (ACF) is an attractive interconnect material because of its fine pitch capability. Anisotropic conductive-adhesive film is a thermosetting, epoxy matrix impregnated with a small amount of electrically conductive particles. During component assembly, the epoxy resin is cured to provide mechanical connection, and the conducting medium provides electrical connection in the z direction. The thermal cure process is critical to develop the ultimate electrical and mechanical properties of the ACF. In this paper, the curing reaction of ACF was studied with a differential scanning calorimeter (DSC) under isothermal conditions in the range of 120-180°C. An autocatalyzed kinetic model was used to describe the curing reaction. The rate constant and the reaction orders were determined and used to predict the progress of the curing reaction. A good agreement is found between the proposed kinetic model and the experimental reaction-rate data. The reaction-rate constants were correlated with the isothermal temperature by the Arrhenius equation. The glass-transition temperature also has been studied as a function of cure degree and moisture absorption.

Effect of spin coating on the curing rate of epoxy adhesive for the fabrication of a polymer optical waveguide

“…Viscosity increases in proportion with the cross-linking and, hence, reduces the mobility of the polymer molecules for further reaction. 2 The degree of curing of the spin-coated adhesive film (over three locations, Fig. 4a) was also measured using the same FTIR method.…”

“…1 The physical, optical, and thermomechanical properties of the cured adhesives depend on the degree of curing of the adhesive constituents. 2 Ultraviolet (UV) curing is a process applied to polymerize the adhesives compounds to achieve the transition from liquid to solid as a result of their exposure to UV radiation. It is an attractive alternative to conventional curing because it offers several distinct advantages.…”

ACF Curing Process Optimization for Chip-on-Glass (COG) Considering Mechanical and Electrical Properties of Joints

“…Usually, the instantaneous change of the conversion rate is defined as: (10) Herein, ΔQ is the exothermic heat, expressed as heat per mol of reacting groups ( KJ ·mol -1 ) or per mass of materials (J·g -1 ). Usually, the curing kinetics equations of thermosetting materials are classified into two general categories: nth order and autocatalytic, which represents the overall process if more than one chemical reaction occurs simultaneously during curing (Chan, et al, 2003). For thermosetting materials that follow nth order kinetics, the rate of conversion is usually proportional to the concentration of unreacted sections (Chan, et al, 2003), i.e.…”

“…Usually, the curing kinetics equations of thermosetting materials are classified into two general categories: nth order and autocatalytic, which represents the overall process if more than one chemical reaction occurs simultaneously during curing (Chan, et al, 2003). For thermosetting materials that follow nth order kinetics, the rate of conversion is usually proportional to the concentration of unreacted sections (Chan, et al, 2003), i.e. (11) Herein, n is the reaction order, and k is the temperature-dependent rate constant given by the Arrhenius equation: (12) Herein, E is the activation energy, R is the gas constant, T is the absolute temperature, and A is the frequency factor.…”

A continuous contact resistance monitoring during the temperature ramp of anisotropic conductive adhesive film joint

“…The T g is the temperature at which an amorphous or semi-crystalline polymer is transformed to the rubbery viscous state. 9 Figure 4 shows a typical TMA scan for the cured ACF. The specimen exhibits a lower CTE of 57 ppm/°C at temperatures below 120°C and a higher CTE of 135 ppm/°C at temperatures above 140°C.…”