Research On Preparation Technology And Structure Improvement Of Alloy Thin Film Strain Sensor

Modern cutting processing is developing towards intelligence,precision,integration and miniaturization.Real-time online measurement of cutting force is a necessary means to realize the intelligentization of cutting tools.The embedded alloy thin film strain sensor of cutting tools is to realize the monitoring of cutting during the cutting process.An effective method of force,the basic research of tool embedded thin film sensor to measure cutting force has important scientific significance and engineering application value.The thin film sensor is divided into substrate,a transition layer,an insulating layer,a sensitive layer and a protective layer from top to bottom.The sensitive layer is the core structure to realize the force measurement function.In order to obtain a thin film sensor with excellent performance,there must be a systematic and scientific process plan in the preparation,structure and performance testing of the thin film.In this paper,through theoretical analysis and experimental research methods and methods,some problems that still exist in the process plan at this stage are deeply discussed,and a series of process optimization methods are tried to solve them.In the preparation process of thin-film resistor grids,the photoresist may cause wrinkling and peeling due to some unreasonable combination of process parameters.In order to explore the photoresist hard film process parameters suitable for etching thin-film resistor grids,the spin coating can be improved.For the photoresist performance on the surface of the film layer,this article first uses the orthogonal test method to optimize the thickness of the sensitive layer,the baking temperature,the duration and the photoresist model as the optimization object of the hard film process.In the main technical parameters of the photoresist according to the degree of importance,adhesion and etching resistance are selected as the evaluation indicators of photoresist performance,and the best combination of process parameters is initially obtained through extreme poor analysis.Then,based on the orthogonal test data,the LS-SVM and BP neural network intelligent algorithms are combined to establish the prediction model of photoresist adhesion and corrosion resistance.Subsequently,a more reliable predictive model is selected,and the method of controlling variables is used to systematically analyze the influence trend of the above process parameters on the two evaluation indicators,and finally obtain the constraint conditions of each process parameter.After the etching of the thin film resistor grid is completed,in order to reduce the resistance value of the sputtered thin film resistor grid and improve the adhesion of the film,the thin film sensor on the 304 stainless steel substrate with the Ni Cr film as the sensitive layer is annealed in a N₂ environment.During the test,it was found that different annealing processes(300,350,400,450 and 500°C)can effectively reduce the resistance value of the thin film resistor gate.The decrease is the largest at 450°C,and the resistance value changes to 1.77 k?,the smaller resistance value can make the thin film sensor detect smaller strain and have higher measurement accuracy;the film has the strongest adhesion on the substrate at350°C and 30 minutes,which is better than that of the sputtering state.The film is about 37.5%high.The increase in adhesion makes the film less likely to break and fall off prematurely,which can expand the measurement force range;in addition,the results of the atomic force microscope(AFM)show that the annealing at a higher annealing temperature The film has a high surface roughness,which may be caused by the agglomeration of the original grains after annealing;moreover,the temperature coefficient of resistance(TCR)and the strain sensitivity coefficient(k_n)increase with the increase of the annealing temperature,but kn increases slowly.In order to further improve the strain performance of the thin film resistance grid,based on the existing thin film sensor structure,two improved structures that can improve the strain sensitivity of the strain thin film sensor are designed.The first is to construct a"graphene-Ni Cr composite film"as the thin film sensor structure of the sensitive layer,the second is to design the elastic structure of the double-ended support beam film on the thin film sensor.The structure can be divided into two formation methods.One is to directly deposit the elastic structure of the double-ended support beam film on the insulating layer.The second is to process elastic grooves on the 304 stainless steel substrate to form the elastic structure of the double-ended support beam film;Then the advantages of the thin film sensors of these two structures compared with the thin film sensors prepared by the conventional conventional sputtering deposition method are discussed separately;Finally,the preparation process of these two structures is analyzed and researched.