Direct production of conductive/resistive traces on a flexible substrate using a computer/printer system

Currently, strain gage instrumentation of rocket motor cases involves individually attaching each gage and running lengthy lead wires from the gages to the signal conditioning equipment. The application of many individual gages is time consuming. Also, the lead wires introduce errors due to their resistance and the electrical noise they absorb. Two areas of interest have been identified which deal with simultaneously applying multiple strain gages and locating the signal conditioning circuitry adjacent to the gages. Both of these areas of interest involve the production of conductive and resistive traces on flexible substrates. It is desired to produce these traces directly using computer control without having to use a silk screening process or etching of copper. The objectives of this study were to: (1) identify technologies which potentially could be developed to produce resistive strain gages and conductive traces for electronic circuitry on thin flexible substrates; (2) determine the current capabilities of these technologies as they pertain to the production of conductive and resistive traces; and (3) investigate the technologies to determine the problems which must be overcome in order to produce consistent and reliable results. Although control and timing difficulties present a problem with producing uniform traces, resistances of less than 0.4 Ω/cm (1 Ω/in) were produced with a width of about 1.0 mm (0.04 in)