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.

Abstract: An apparatus and method are disclosed for preparing electrically conductive traces on a circuit board using an additive technology. The traces are directly written in a serial process with each trace being able to be individually insulated. The apparatus includes an extrusion element for extruding a first material and a stage. The stage is for holding the extrusion element and the circuit board in relative proximity and for producing relative motion between the extrusion element and the circuit board in order to extrude the first material onto the surface of the circuit board along preselected paths to produce the electrically conductive traces. According to the method of invention, a first polymerizable material is extruded onto a circuit substrate support along preselected paths to form traces, and the first polymerizable material is polymerized, the first polymerizable material being conductive after polymerization.