Temperature-Control Calibration for a Joule-Heating Thermal Shock Tester

Kidus Abebe

Faculty Supervisor: Amit Datye

Kidus Abebe

Thermal shock testing of high-performance materials is valuable for the high-throughput development and testing of next-generation aerospace alloys and coatings. In previous years, students in the Yale Nanoprobe Group developed a custom LabVIEW-controlled device capable of achieving high temperature thermal shock through the Joule heating of a p++ dopped silicon wafer. The device is designed to apply thermal cycles onto a sample, so a user can specify a certain number of cycles, the cycle “on” time, and the cycle “off” time. However, the thermal shock tester was initially operated by direct user input of current values, placing the burden of temperature estimation on the operator and introducing significant inconsistency between tests. In this project, we developed a temperature-mapping algorithm to bridge that gap, enabling users to specify a target temperature directly rather than an abstract current setpoint. The mapping procedure was designed around an on-time of 20 seconds and an off-time of 5 seconds — a duty cycle chosen to allow the sample to reach thermal steady-state during each heating pulse while permitting cool-down between cycles. Temperature and current data were collected across a range of input current values, and MATLAB was used to extract the mean current and corresponding mean temperature during the “on” phase of each cycle. These averaged data points were then plotted and fitted to obtain a linear relationship between input current and achieved wafer temperature. This calibration equation was subsequently implemented directly in the LabVIEW control environment. The updated interface accepts a user-defined target temperature, internally converts it to the appropriate current setpoint via the linear mapping, and commands the hardware accordingly, eliminating the need for operator-side unit conversion and improving test-to-test repeatability.