1-Thick Film Technology-Lasering Of
Lasering of substrates
Most used substrates are made of 96% Alumina Al2O3. Alumina is very hard and not very machinable, therefore lasering of the material is the most efficient way to machine it. The thick film process is also a process of miniaturization where one substrates normally contain many units (final circuits), with the lasering it is possible to scribe, profile and drill holes. Scribing is a lasering process where a line of laser pulses are fire into the material and 30-50% of the material is removed, this weakens the substrate, after all other process are done to build the thick film circuit the substrates can easily be divided into single units. Profiling are for example used lot in the sensor, where a circuit need to fit round tubes or other different complex shapes. Drilling of holes, provide via between the two sides of the substrate, normally hole sizes are in the range 0.15-0.2 mm.
Lasering before processing the substrates has a cost advantage to lasering or dicing using diamond saw after processing.
Inks for electrodes, terminals, resistors, dielectric layers etc. are commonly prepared by mixing the metal or ceramic powders required with an organic vehicle to produce a paste for screen-printing. To achieve a homogeneous ink the mixed components of the ink may be passed through a three roll mill. Alternatively, ready made inks may be obtained from one of the many companies offering products for the thick film technologist.