The field of consumer and automotive electronics is becoming increasingly important for applications of mmWave technology. Innovative approaches and materials for electronics packaging are currently being developed. The focus on improving the performance and the reliability induces an increased demand for in-depth analysis and testing. In this study, the thermo-mechanical behaviour of mmWave modules mounted onto a standard or a hybrid substrate is investigated. A board level reliability study is performed according to the automotive standard AEC-Q100 grade 1 specification. Findings after temperature cycling test at - 55 °C to + 150 °C will be presented. Commercially available FR4 substrate materials with high-Tg and suitable low transmission loss characteristics are selected to meet both automotive and high frequency requirements. The mmWave module is made of one low loss material. The impact of two substrate configurations on the board level reliability of the mmWave module is investigated. Considering the different material properties and the large package dimension (30 x 12 mm²) temperature changes will cause severe stress to the board level solder interconnects (alloy SAC305, diameter 600 μm). The performance of the mmWave test vehicle in terms of the solder joint damage behaviour under temperature cycling testing will be analysed in this study. Both specimen configurations successfully passed electrical tests after up to 1,000 cycles temperature cycling. Cross sections and electrical analysis show a better performance of the hybrid configuration at high cycle counts.