Formulation of composite resistive pastes for fabrication of micro-heaters

Abstract

We investigate in this work the formulation of composite resistive pastes based on epoxy resins and graphite for micro-heater manufacturing via thick-film technology. These resistive pastes are designed for screenprinting onto a printed circuit board (PCB) substrate; further coating with expandable polydimethylsiloxane (PDMS), a composite based on an elastomeric matrix and expandable microspheres, results in one-shot thermal actuators allowing pumping and sealing in disposable microfluidic lab-on-a-chip devices. The resistive paste must therefore have controlled rheology and resistivity, and exhibit good temperature stability in order to allow high heating power densities. This paper details the formulation and characterisation of suitable epoxy-graphite resistive composites, and the control of their properties through solvents.

Electrical stress on film resistive structures on different substrates

“…Similar traces of the resistance behavior were presented in [9] for thermal cycling and in [10] for over-load for long time (over-load life characteristic).…”

Tuneable PTC effect in polymer-wax-carbon composite resistors

“…Especially, for thick-film conductive and resistive materials, the use of organic resin matrices allows compatibility with a wide range of substrates, albeit at the cost of lower stability than their cermet analogues (Dziedzic et al, 1993;Serra et al, 2010).…”

Piezoresistive effect in epoxy–graphite composites

“…Several properties of the material used, such as mechanical or electrical (depending on the type of sensor) must be therefore considered. In a previous work [1], we studied the conductivity properties of epoxy-graphite composites, regarding particle size and T g effects, finally leading to the manufacture of micro-heaters based on these pastes. To continue the characterization of our pastes, we observed the piezoresistive behavior, which is of high interest for mechanical sensors.…”