Conductive Inks (Polymer Thick Film)

What are Conductive Inks?

Conductive inks (also called polymer thick films) from DuPont Microcircuit Materials bring sophisticated multilayer designs within reach of virtually every membrane switch designer. All DuPont conductive inks are composed of three main components: polymer binder, conductive phase, and solvent.

The polymer binder, when combined with the conductive and solvent phases, is a liquid that can be "printed" onto polyester film, forming flexible printed circuits. After printing, the solvent is evaporated out of the mixture, leaving a stable conductive pattern on the flexible substrate.

What Type of Solvents can be Used With Conductive Ink?

Different types of solvents may be used in DuPont conductive inks. Butyl acetate is used for rapid evaporation in flexographic and rotogravure printing. Glycol esters are used when evaporation time is not an issue and screen-printing is employed.

The conductive material may be silver flakes or spheres, a blend of carbon/graphite particles or a blend of silver flakes/carbon particles. Particle sizes range from 0.5 microns to 8.0 microns in diameter. When these flakes or particles are suspended in the polymer binder, they are randomly spaced through the liquid. Once the solvent is evaporated, they condense, forming a conductive path or circuit. Of the conductive materials, silver is the least resistive and the most expensive while carbon/graphite offers the best combination of low resistance and low price.