A Research Of Trimming Process For NiCrAlSi Alloy Chip Resistor

Having advantages of small volume,high precision and good stability of chip resistor mainly fine-tuned by laser trimmer in automatic production.The resistance of precise alloy chip resistor is usually milliohm level @0.1 m? to 500 m?.In order to make its tolerance reach 1%,0.5% and 0.1% to improve the precision of resistance and the yield of production,it mainly uses low laser power surface trimming technology and mechanical drilling or grinding technology.Considering above two technologies are more time-consuming and lower production efficiency,the more efficient high power laser trimming technology for NiCrAlSi alloy resistor trimming experiments is used.Firstly,system compositions,main features of machine,cutting principle and measuring principle of the high power laser trimmer were introduced.Secondly,the resistance calculation method of alloy resistor with cutting paths was introduced.And ANSYS was used to simulate the resistance changing with cut length of the 2D NiCrAlSi alloy resistor under the influence of cutting path which is I cut.Thirdly,introducing several models describing the turbulent flow field and focusing on "Realizable k-e model".Finally,using Gambit and Fluent to simulate the jet field distribution of nozzle laser cutting head of in the free-space and the impinging-sapce.Under the set simulation condition @2.5Mpa,each side of kerf has a flow static area,diameter is around 160 um,was observed.Experiment: The influence of eight process parameters on cutting quality of the alloy resistor were respectively discussed.Process parameters are laser power,laser frequency,cutting speed,nozzle's aperture,focal shift,working distance,assist gas pressure and laser beam incident angle,of which laser power,nozzle's aperture,working distance,assist gas pressure and laser beam incident angle have more significant effect on the slag of alloy resistor.Optimization experiment: Experiment of alloy resistor trimming process parameters by using orthogonal test method was carried out.Results of orthogonal experiment were respectively processed by the method of intuitive analysis and signalto-noise ratio analysis,and predicted optimized parameters had been evaluated.The final conclusions show that intuitive analysis can optimize process parameters,but it can't reach the trimming requirement.However,another method can make a obvious improvement on the cutting quality.The optimized process parameters of signal-tonoise ratio method were set for NiCrAlSi alloy chip resistor trimming and cutting results meet trimming requirements well.