Paste for screenprinting electric structures onto carrier substrates

Pastes are used in thick film technology in order to produce electrical components, such as resistors, capacitor layers, and insulating glass layers between printed conductor structures, as well as coating or protective layers which isolate a circuit applied to a ceramic substrate from the surrounding environment, on ceramic substrates. The composition of known thick film pastes is described, for example, in "Herbert Reichl; Hybridintegration: Technologie u. Entwurf von Dickschichtschaltungen [Hybrid Integration: Technology and Design of Thick Film Circuits]; Huthig Verlag, Heidelberg, 1988, pages 37 to 63". Thick film pastes are printed on a ceramic substrate in the screen printing method. Known pastes contain a mixture of small solid particles having a high softening point or high sintering temperature and an inorganic binding agent, for example a glass having a low sintering temperature, which are dispersed in a vaporizable organic binding agent. The solid particles typically have a diameter of around 0.1 to p3 m. The dispersions have the consistency of a paste and have a rheology which makes the paste suitable for screen printing. Organic binding agents contain different additives such as binding and Theological agents, which increase the printability of the paste. For printing resistors, metal oxides, which determine the resistor's conductivity, are also added to the paste. After screen printing, the printed structures are fired in a sintering process, the organic components being completely evaporated out of the paste or pyrolized. At a temperature below the sintering temperature of the solid particles,but above the sintering temperature of the inorganic binding agent, the latter is softened and flows around the non-sintering solid particles. Finished electrical structures have a thermal expansion behavior after cooling that is different from that of the substrate. Therefore crack formation occurs frequently in resistor structures in the case of temperature variations, whereby the electrical properties are disadvantageously influenced. In the extreme case the resistor completely fails. Cracks in a printed coating layer or insulation layer lead to a disadvantageous penetration of harmful substances or a short circuit of the printed conductors. A paste for screen printing of electrical structures on substrates, in particular ceramic substrates, which includes a mixture of inorganic solid particles having high sintering temperature and an inorganic bind