2. Experimental section
2.1. Fabrication of ACFs
The epoxy resin of bisphenol A type, NBR and silane
coupling agent were dissolved in toluene at 60 ◦C over
5 h, the solution was cooled to room temperature and
a micro-encapsulated imidazole (Asahi Chemical Ind.,
Novacure® HX3748) was added as curing agent. Then
Au/Ni coated polystyrene beads (Sekisui Fine Chemical
Co.) cross-linked with divinyl-benzene [5,6] were added to
make a final 45 wt.% adhesive solution. Our formulation
is shown in Table 1. The particles were 5 and 10 m in
diameter. The thermoset resin of the mixture of epoxy and
NBR was used as the insulating resin because of its strong
adhesion to various substrates (ITO glass, flexible printed
circuit (FPC) and TAB, etc.) and favorable melt viscosity.
The solution was coated using the comma direct coating
method onto a silicone-treated polyethylene terephthalate
(PET) film 50 m in thickness (release film RR CF503 provided
by Saehan). The adhesive layer (ACF layer) at dry
state after coating was about 25 m in thickness. The PET
film acts as a liner or separator for the resulting ACF.
2.2. Equipment
A Perkin-Elmer DSC-7 was used to measure the glass
transition temperature (Tg) of the epoxy/rubber thermoset
resin. The dynamic scanning temperature ranges from −10