Research On Crucial Techniques For Micro-catheter Tip Intracranial Pressure Sensors

ICP(Intracranial Pressure)monitoring has been widely used in many areas in medicalsurveillance. Catheter-tip, as one of the most important parts in the monitoring, is stillexpensive in the market. There are mainly two reasons, one side, the fabrication and relevanttechnology is still mainly concentrated in some developed countries. The other side, themature product was still hand-made at present.There are two kinds of catheter-tip, fiber optic catheter-tip and strain gauge catheter-tip.As to the simple packaging process and low-cost, strain gauge catheter-tip is more widelyused in the world. In this dissertation, the packaging technology of the sensor was discussed.Using flip-chip to develop a new catheter-tip based on ACF(Anisotropic Conductive Film)and MS763.There are two kinds of packaging, wire bonding and flip chip. Wire bonding wasdeveloped for decades, and the technology is relatively mature. Not only the bonding time,bonding pressure and the power, but also many other factors affect the bonding quality. Wirebonding need a substrate and the size is larger. Flip chip technology omit the substrate andreduce the size of packaging. Using ACF for flip chip could simplify the process.The stain gauge catheter-tip is made up by metal shell,MS763-A die chip, ACF,FPC andRTV. The whole packaging size is less than2mm,which is complied with the medicalrequirements.First of all, based on the application of catheter-tip, using ACF and FPC for sensorpackaging, a new flip-chip technology is proposed. Measuring the contact resistance of ACFthrough four-terminal method. Design the structure transformation, and ensure the packagingtemperature, pressure and time.Secondly, design the related fixtures based on the packaging process. The wholeworkbench is a three dimensions micro motion worktable. FPC and the die is fixed by vacsorb. And the die requires a boundary wall to ensure the die.Finally, based on the characteristic and application environment.PGA309signalconditioner from Texas Instrument is used to design calibration system. The Interface circuitsand PCB is designed and using this to solve the problems of signal amplification, linearizationand temperature compensation.