Собственно, меня этот вопрос заинтересовал настолько, что я

The introduction of Pb-free solder-based TIM materials posed significant integration challenges. The STIM needed to relieve the mechanical stress caused by CTE mismatch of the integrated heat spreader lid and the silicon die and to minimize stress transfer to the silicon die during thermal cycling [6]. The thermal conductivity and the mechanical compliance requirements resulted in the development and qualification of low melting temperatures (157°C Tm), low mechanical yield strength (4-6 MPa), and relatively high thermal conductivity (~87 W/m°K) pure Indium (In) metal for STIM applications.