Research On Cooling Performance And Thermodynamic Correspondence Of Thermoelectric Cooler Based On Multi-physical Field Coupling

Thermoelectric cooling sheets are widely used as solid heat pumps for heat dissipation and precise temperature control of electronic devices and photoelectric conversion devices.Under the premise that the optimization of the figure of merit of thermoelectric materials has not made a major breakthrough,the improvement of the cooling performance of the cooling sheet mainly lies in the optimization of the structural parameters.With the change of the structural parameters of the thermoelectric cooling sheet,the interaction of the materials will inevitably cause the change of the internal thermal stress distribution,which will endanger the reliability of the device.In this paper,the cooling performance and thermal stress changes of thermoelectric cooling sheets are comprehensively considered.Based on the heat transfer theory and the basic laws of thermoelectric cooling technology,a thermalelectricity-mechanical multiphysics coupling model of thermoelectric cooling sheets is established.The influence of material physical parameters,the cooling performance and thermodynamic response of thermoelectric cooling sheet were studied and analyzed.In this paper,the effects of current,thermoelectric arm,thickness of ceramic substrate and thickness of copper sheet on the cooling performance and thermal stress distribution at different positions of the thermoelectric cooler were studied.The study found that the maximum thermal stress is at the edge of the thermoelectric cooling chip.With the increase of the current,the cooling performance of the cooling chip is better and the reliability is decreased.The side length of the thermoelectric arm section is increased from 1.2 mm to 1.6 mm,the cooling capacity is increased by 25.2%,and the maximum thermal stress is increased by 31 MPa.The height of the thermoelectric arm was increased from 1.6 mm to 2 mm,the cooling capacity was reduced by 20.7%,and the maximum thermal stress was reduced by 38 MPa.The thickness of the ceramic substrate was increased from 0.3 mm to 1 mm,and the maximum thermal stress was reduced by 24 MPa.The thickness of the copper sheet is increased from 0.1 mm to 0.3mm,the cooling capacity is increased by 7.7%,and the maximum thermal stress is increased by 14 MPa.Combined with the performance of the cooling sheet and the change law of thermal stress,the size of each design parameter was changed.After the change,the cooling capacity of the device was increased by 23.5%,and the maximum thermal stress was reduced by 15 MPa.In this paper,the variable parameter and defect analysis are carried out on the most vulnerable part of the solder in the thermoelectric cooler.Firstly,the effects of the side length and thickness of the solder section on the performance and thermal response of the cooling chip were studied.The study found that when the side length of the solder section is 0.95～1.00786 times the size of the thermoelectric arm,the maximum temperature difference of the cooling piece is increased by 4.6 K,and 0.975 times is the best.At this time,the maximum thermal stress of the device is reduced by 10 MPa;the thickness of the solder is 0.0825～0.0958 mm,the maximum temperature difference of the cooling sheet is increased by 5.2 K,and the maximum thermal stress is reduced by 9 MPa.Then,the solder defects are discussed,and the influence of the size,position,shape and number of inevitable solder cracks and voids on the maximum thermal stress near the solder is studied,and suggestions for improving the reliability of the thermoelectric cooler are given.The research results play an important role in determining the correlation between the thermal response and structure of the thermoelectric cooling chip,suppressing the thermal stress level and solder defects,promoting the optimal design of the packaging structure of the thermoelectric cooling chip,and improving the cooling performance and reliability of the device.