| abstract |
Materials are disclosed which are used to produce traces on a circuit board by means of extrusion. The materials are polymer thick films (PTF) which are thixotropic. Conductive traces are composed of conductive particles, a resin and hardener, and two solvents, one having a relatively high volatility and one having a relatively low volatility. Thus when a newly deposited trace is subjected to a stream of hot air, the fast solvent will substantially evaporate leaving a firm paste behind over which another layer of PTF can be written without causing interference between the layers. The slow solvent then permits the various layers of traces to be polymerized together at the same time in a one step operation. The insulative material is similar to the conductive material in that it includes a resin and hardener and two solvents of differening volatility. In addition, in the preferred mode, it includes a gelling agent. |