Digital Printing
With the aid of inkjet technology it should be possible to produce resistors with a tolerance of ± 5% without using a trimming process. Inkjet printing technology is based on squeezing tiny amounts of fluid (approx. 10-100 pl) out of a reservoir, so that they concentrate into spherical droplets under the influence of the surface tension. Printing speed and volume of the drops can be exactly reproduced.
The chemistry of the ink must be adjusted precisely to the print head. From a chemical point of view, inks for electronic components are no longer comparable to normal color inks. For electronic functions to be possible at all, approximately 20% of a resistor ink must be composed of conductive particles, while for color printing 5% of dyestuffs is sufficient. In addtion the chemistry must be stable in the various processes to which a printed circuit board is subjected during production, including temperatures of up to 250°C and pressures of up to 20 bar.
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