In this article, a microchannel thermal management system (MTMS) with the two-phase flow using the refrigerant R1234yf with low global warming potential is presented. The thermal test vehicles (TTVs) were made of either single or multiple thermal test chips embedded in the substrates, which were then attached to the MTMS. The system included two identical aluminum microchannel heat sinks (MHSs) connected in series in the cooling loop, which also consisted of a gas flowmeter, a miniature compressor, a condenser, a throttling device, and accessory measurement components. The experimental results showed that the thermal management system could dissipate a heat flux of 526 W/cm2 while maintaining the junction temperature below 120 °C. For SiC mosfet with a higher junction temperature, e.g., 175 °C, the current system is expected to dissipate a heat flux as high as about 750 W/cm2. The effects of the rotational speed of the compressor, the opening of the throttling device, TTV layout on MHS, and a downstream heater on the cooling performance of the system were analyzed in detail. The study shows that the present thermal management with a two-phase flow system is a promising cooling technology for the high heat flux SiC devices.

Nowadays, fan-out package is regarded as one of the latest and most potential technologies because it possesses lower cost, thinner profile, and better electrical performance and thermal performance. However, thermally induced warpage in the molding process is a critical issue due to the larger wafer or panel size, the shrinkage of epoxy mold compound (EMC) during the curing stage, and the mismatch of coefficient of thermal expansion (CTE) among the constituent materials during the cooling stage, which needs to be controlled effectively for successful subsequent process of the fan-out package. In this paper, a novel $320 x 320$-mm² panel-level fan-out package based on ``Die Last'' process is developed. A coreless substrate with redistribution layer is fabricated and bonded onto a low-CTE and high-glass-transition-temperature (Tg) FR4 carrier through thermal release film. The thermally induced warpage issue in the molding process is investigated. A warpage simulation method is presented and verified by Shadow Moiré experiment. The error between the simulation and experimental results is about 4.8%. For the warpage optimization analysis, the effect of geometry structure on the warpage is first investigated by the design of simulation approach. Full factor experiment is conducted, and Minitab statistical software is utilized to analyze the effect of the geometry structure on warpage. It is found that decreasing die thickness and molding thicker EMC can effectively decrease the warpage. Then, the effects of molding temperature and in-plane CTE of FR4 on warpage are studied, respectively. When molding temperature is 120 °C and in-plane CTE of FR4 decreases to 10.5 ppm/°C, the thermally induced warpage in the molding process is only about 0.31 mm, thus subsequent process of fan-out package can be conducted successfully.