Study Of Directly Fabricating Thick Film Thermosensor By Laser Micro-Cladding Technique

Sensors are very important products for the information society. As one of the most important sensors, thick film thermosensors are developing towards to smaller, higher intergratation and higher precise. Comparing with the traditional technique of fabricating thick film thermosensor, the laser micro-cladding technique is more flexible which can shorten product preparation cycle by saving the producing of template. Furthermore, the sensors fabricated by this technique may be more precise with better quality. In this thesis, thick film thermosensor is firstly fabricated on 96%wt Al2O3 ceramic substrate successfully by laser micro-cladding thick film paste of the thermosensor. The maximum scanning velocity is 70mm/s. The sensors have excellent definition and narrow width (minimum 60μm) with TCR 2330ppm/℃, time answering hot 2.3s and linearity tolerance <1℃. Besides, the fabricated thermosensors have excellent repeated properties and stability after heat shock. The parameters affecting sensor performance of all working procedures are studied. The technique of the electrode preparation is also studied. On the basis of which the best technique routine-fabricating electrode after having prepared resistor-is suggested and the co-sintering technique for both the electrode and the thermosensor pastes simultaneously is brought forth. The performances about the sensors fabricated by the laser micro-cladding technique are characterized. The experimental results demonstrate that the thermosensors fabricated by laser micro-cladding have excellent performances, which are a little better than those fabricated by the traditional silk screen printing methods. By analyzing the micro configuration of the sensors, the elements of fabricating thick film thermosensor by laser micro-cladding technique are studied systematically. A simple model about these elements is established. On the basis of analyzing the conductive elements about the thermosensor pastes, the importance of element Cu is brought forth. The element Cu reduced the resistance of thermosensor and enhanced the TCR of resistor.