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The curing reaction of a promising “no flow” flip chip underfill encapsulant is investigated by using a differential scanning calorimeter. It is found that the tested underfill can reach complete cure within 20 minutes at various cure temperatures. It is also shown that this “no flow” underfill could fully cure within one minute at 160°C after being heated at 220°C for one minute, demonstrating that this “no flow” underfill can be completely cured during the solder reflow cycle. The reaction order and the rate constant are determined to describe the curing progress. It is shown that the autocatalytic effect dominates the reaction kinetics.

This paper investigates the variations in electrical properties of a typical isotropic conductive adhesive (ICA) made with an epoxy‐based binder that are caused by differences in the curing conditions.

In‐situ monitoring of the various processes that were used to cure the ICA revealed that electrical conduction in the ICA specimens depends on both the high‐temperature curing conditions and the conditions during cooling to temperatures below the glass transition temperature (T_g).

The electrical resistivity of the cured ICA specimens after cooling to ambient temperature decreased with increasing degree of conversion, tending towards a convergence value that decreased with increasing curing temperature. The electrical resistivity of the specimens also varied significantly depending on the subsequent annealing process. However, the electrical resistivity achieved after annealing at temperatures above the curing temperatures clearly depended on the particular curing temperature that was used. The characteristics of the polymer structure in the adhesive binder are considered to be different, depending on the curing temperature, and this affects the electrical properties of the ICA;, i.e. the characteristics of the polymer structure obtained during the curing process affect the electrical resistance of the ICA, even after subsequent annealing processes.

This paper discusses generalities of variation in the electrical properties of ICAs during heating and cooling processes. The variation in behaviour in practice will differ depending on the type of adhesive binder in the ICA.

This paper clarifies how the electrical properties of ICAs evolve during the curing, annealing and cooling processes.

Anisotropic conductive film (ACF) is now an attractive technology for direct mounting of chips onto the substrate as an alternative to lead‐free solders. However, despite its various advantages over other technologies, it also has many unresolved reliability issues. For instance, the performance of ACF assembly in high temperature applications is questionable. The purpose of this paper is to study the effect of bonding temperatures on the curing of ACFs, and their mechanical and electrical performance after high temperature ageing.

In the work presented in this paper, the curing degree of an ACF at different bonding temperatures was measured using a differential scanning calorimeter. The adhesion strength and the contact resistance of ACF bonded chip‐on‐flex assembly were measured before and after thermal ageing and the results were correlated with the curing degree of ACF. The ACF was an epoxy‐based adhesive in which Au‐Ni coated polymer particles were randomly dispersed.

The results showed that higher bonding temperatures had resulted in better ACF curing and stronger adhesion. After ageing, the adhesion strength increased for the samples bonded at lower temperatures and decreased for the samples bonded at higher temperatures. ACF assemblies with higher degrees of curing showed smaller increases in contact resistance after ageing. Conduction gaps at the bump‐particle and/or particle‐pad interfaces were found with the help of scanning electron microscopy and are thought to be the root cause of the increase in contact resistance.

The present study focuses on the effect of bonding temperatures on the curing of ACFs, and their adhesion strength and electrical performances after high temperature ageing. The results of this study may help the development of ACFs with higher heat resistance, so that ACFs can be considered as an alternative to lead‐free solders.