Research On The Engineering Problem Of Multi-functional Variable Temperature Stage For Dielectric Performance Testing

The combination of multi-functional variable temperature stage(THMS600,Linkam),LCR impedance analyzer and test fixture can realize the measurement of dielectric performance in temperature range from-196? to 600?.At the same time,system error is inevitable because the dielectric testing needs to be implemented in cooperation with a variable temperature stage,a coaxial cable,a sample fixture,a temperature controller,etc.In this paper,two basic problems,the accurate measurement of temperature and the coupling capacitance of the test system during the dielectric test,were mainly analyzed.In addition,several engineering questions such as the design and optimization of the test fixture,the temperature field calibration of the variable temperature stage,the determination and reduction of the coupling capacitance were investigated.Some experimental results were obtained as follows.(1)The temperature of test stage was calibrated through two experiments.In order to measure the actual temperature of measuring point,a thermal resistance temperature measurement system is be set up on the basis of existing instruments(THMS600,Linkam).First of all,for a given temperature,the temperature error(AT)between actual value of measurement point of the variable temperature stage and the corresponding reading on the instrumental software was studied.Then,above temperature error was investigated by the same method when the temperature stage was heated with different increasing speeds,and change the temperature measurement point to compare.The experimental results showed that the actual temperature measured at each point will be lower than the software preset temperature.Meanwhile,when the temperature is higher,the ?T will be larger.In addition,with the increase of heating rates,the value of ?T will become smaller.Generally,when the temperature change rate is 1?/min,the value of ?T will be relatively small,and the change curve of ?T will be smoother compared to other rates.(2)The error source of dielectric property testing system was analyzed by an experiment.Firstly,the LCR impedance analyzer is used to directly measure the dielectric property data of BaTi03.Then,the dielectric property test system independently designed by the laboratory is used to measure the dielectric property data of the same material under the same conditions.Finally,the two sets of measured data are compared.The experimental results show that the difference in capacitance obtained by the experiment is-0.6%.Compared with the capacitance accuracy specified in the national standard ±(1%±0.0005),the difference of the capacitance meets the national standard.The error of dielectric loss is-28.7%.Compared with the accuracy of dielectric loss specified in the national standard of ±(5%±0.0005),the dielectric loss does not meet the national standard.In conclusion,the reason may be that the test system independently designed by the laboratory generated a certain coupling capacitance during the experiment,which affected the test results of the electrical properties of the samples to be tested in the container.In addition,the contact pressure between the fixture and the test sample and the quality of the solder wire used to connect the fixture to the test signal line may affect the test data.We have realized the function of dielectric performance test without affecting the test performance of the variable temperature stage,and at the same time,we have carried out an error analysis on the system built,which provides a new idea for the research of the variable temperature stage.