Before any circuit can be manufactured, the schematic drawings are translated into a series of screen printing masks. It is the sequential printing of these masks which produces the final interconnect, complete with resistors and component mounting pads.

1st Stage
Screen print the conductor interconnects and isolation pads at the conductor crossover points onto a substrate of 96% pure Alumina. Each layer of print is dried at 125^oC.

2nd Stage
Screen print resistors, which are based on a Ruthenium oxide, chosen for its high temperature characteristics, good stability and TCR properties. Each decade of resistor print is dried at 125°C. The substrate is then fired at 850°C through a temperature profiled furnace.

3rd Stage
Trim the resistors. This is achieved by means of laser trimming normally to a tolerance of 0.5%. At this stage, different shapes of cuts can be achieved to take account of voltage stress, power stress and stability with life, etc.

Final Stage 
Populate the substrate with surface mount components/chip and wire. Then attachment of edge connectors or encapsulation into ceramic/metal package, whichever is appropriate.