Study On Reability Analysis And Lifetime Prediction For Magnetic Heads

The magnetic storage technology is faced with new and more challenging tasks with the rapid development of modern solid state storage,optical storage and increasing need of industrial production.The distributed magnetic storage technology pave a new effective way for the aerospace and other confidential industrial storage fields,attracting many practitioner and researchers' attention.The reliability and the life of magnetic storage devices are the key to storage technology.Due to the size of magnetic storage element is very small,so the study of magnetic storage devices and their components are mainly concentrated in the United States and Japan.Moreover almost exclusively for the whole life of the storage device.And the number of analyzing the single element and key factor's life is very small.The main tool of the text is ANSYS and MATLAB,combining with production practice,and further studying the magnetic head built-in DFH control components,head arm connecting the life and reliability of solder joints.In addition,it carefully analyzes the saturated thickness of lubricating oil that affects the life and reliability of the magnetic head.We also establish an improved Markov switching model using for the fault signal transmission of the magnetic head.The main contents of the text are as follows:A new lifetime prediction finite element model used for the Built-DFH in Magnetic Head is studied in detail.This model solves the error superposition failure problem that caused by using the Matlab software to simulate.Combining the actual product validation,the text further analyzes the reliability problems of the design of built-in DFH control components.Furthermore,the following conclusions are drawn:in a new type of DFH 50? calculation results,the strength of thermal effects is about 10%larger than the traditional shield.The life of actual failed samples,the regions that with problems are always connected with the corner of the line.The more corner we have,the more first point of failures are made.The current crowding is mainly based on the current density,changes in the frequency to the current direction and the material itself.The head temperature experiment design is presented after studying the reliability of the magnetic build-in DFH control components.Combined with Atomic Force Microscope(AFM)testing methods,we evaluate the head built-in DFH control components from the perspective of the nature of the deformation and the size.The result shows that,even in a long time over-current circumstances,the processes of the built-in DFH components still belong to the nature of elastic deformation,no permanent plastic deformation occurs.Under the still air cooling conditions,AFM result shows that the relationship of the size of the distortion and energy about the head of the built-in DFH components is linear.Using the Destructive testing methods of pulsed electric field,as the test shows that,the breakdown voltage of the actual product is outside the security zone.Meanwhile,it demonstrates that the method of adding cooled paste to the static disc surface is possible.Thus it would further simplify the experimental process of the head temperature rise.This paper proposes a life prediction model about joint between the head arm link solder and the magnetic built-in DFH control components.The read/write head are made of iron,chromium,nickel,iridium,manganese and other materials.They are easy to corrode.Without protective measures,they will be oxidized,corroded and failed in a short span of ten hours.The IMC can effectively resolve the problems mentioned above.Because AuSn4 growth decreases solder joint mechanical property,this paper mainly reference the AuSn4 growth effect solder.The result shows that the IMC methodology is suitable for forecasting the solder lifetime.And we can draw a conclusion that under the work condition of 60C,when the diffusion constant is 0.015354,the solder lifetime is 14.46 years.We also analyze the reliability of the head micro lead-free solder joints.Th e reliability analysis for the magnetic head includes solders joint early drops spl ash protection and solders joint post failure analysis.In the actual production,while we apply the jetting solder ball bonding(SBB)technology,it is a commo n phenomenon that the solder splash.Combining the laser heating and nitrogen pressure technology,this thesis aimed at building a new double droplet model f or calculating the striking velocity of the solder which is used to connect the B uilt-DFH in Slider,while different parameters of the laser heating and the nitro gen pressure are compared through the orthogonal test.The controllable scannin g magnetic fields and bias are further incorporated and the failure of Magnetic Solder Joint is studied.The result shows that:Before the solder falls,laser energy is t he most important factor affecting the solder splash.After the solder falls,we c an find that the temperature of the melting ball has no decrease during the fall.The temperature of the impinging melting ball depends on its initial value.Th e failure of magnetic solder joint is caused by solder droplet splash and interm etallic compounds.The condition of the well linear relationship between the lubricant thickness and the distance of the point from the disk center is proposed and has been proved.In order to solve the problem caused during the process of surveying the magnetic head lubricating thickness repeatedly.Combined with Atomic Force Microscope(AFM),repeatedly doing dynamic test,the result shows that within the 2.5 nm,where the head read and writ data,the relationship between the lubricant thickness and the distance of the point from the disk center is well linear.From 2.5 nm to the edge of the disk,using the improved Euler method to process the data,we find that the relationship between the difference of the calculated value with actual value and the distance of the point from the disk center a linear too.The article has also carried on the theoretical analysis and the actual confirmation to the experimental result error,finally indicating that due to the local magnetic leakage caused by the air current pressure as well as the disk edge magnetic gap,so,it is difficult to predict the thickness of lubricating oil saturation magnetic head edge.It proposes an improved Markov switching model using for the fault signal transmission of the magnetic head.Upon taking a failure,the frequency of signal transmission is bound to improve and the transportation process will make the channel blockage.It is a topic for many scholars to research that how to response jam is and what degree the information transmission congested that showed the magnetic head has-broke down.Experience date query method commonly used on industrial production,but this method can cause false negative and erroneous judgement.A markow switching model is studied in this dissertation which combines the strength transfer principle,not only make it is ensuring steady state operation of the head early failure,and since the transfer of control of the fuzzy strength was used,it is possible to former fault signal of the positioning.