New Application of Electrically Conductive Adhesive as a Transistor-based Electrical Circuit under AC and DC Currents

Electrically conductive composite adhesives containing ۷۰, ۷۵ and ۸۵ wt% of filler particles (Cu@Ag) and polymer matrix were prepared. Thermal stability and morphology of the prepared adhesives were examined using TG (Thermo-Gravimetry), DSC (Differential Scanning Calorimetry), and Scanning Electron Microscope(SEM) techniques. In the next step, a transistor-based electrical circuit using self-biased common-emitter combination was made from the prepared conductive adhesive as well as a copper board. All of the prepared boards were subjected to DC (۸-۳۰ V) and AC (۱ kHz) currents to evaluate their performance. For these circuits, parameters such as transistor operating points and the voltage gain of the amplifier, were measured. TG and DSC analyses showed that increasing the filler amount from ۷۰ to ۸۵ wt%, reduces the weight loss of the adhesive from ۱۵.۴۸ to ۱۱.۳۵ wt%. Also, effect of increasing the silver amount in Cu@Ag particles on the thermal stability of adhesives at temperatures below ۳۵۰ °C showed that by increasing of the amount of silver from ۲۰ to ۴۰ wt%, has a negligible effect on weight change (about ۲ wt% at ۲۵۰ °C). Both samples showed almost the same overall weight loss at ۳۵۰ °C. Evaluation of circuit performance showed that the changes in circuit width (۱, ۱.۵, and ۲ mm) has no significant effect on the V–I characteristics and voltage gain. The value of these two parameters for all three circuits and also the copper board circuit were the same which indicates the high conductivity of the prepared conductive adhesive.

Keywords:

Conductive adhesive , Cu@Ag particles , Transistor circuit , Silver , copper: Electrical resistivity