All in One Copper Sintering – Die attach and Substrate Attach in Single Step with Soft Tool

Abstract:
An innovative single-step copper sinter process for die and substrate attach with a soft tool set-up is discussed. This enables sintering at low temperatures and pressures, reducing energy costs and thermal stress compared to traditional high-temperature soldering or expensive multi-step silver sintering. The advantages of the innovative process which combines die and substrate attach in one efficient step unlike conventional multi-step methods has the potential to reduce the total isothermal sintering time by atleast 50% and also use a single material stack throughout. The novel copper sinter paste combined with the soft tooling for rapid sintering allows for sintering components of different sizes and thicknesses in a single step with a uniform pressure and temperature distribution and a single exposure to the sintering parameters with a hydrostatic pressure distribution across the system. Most importantly a wellcontrolled cool down ramp is ensured to avoid thermo-mechanical stress after sintering. The results show excellent bondline stability, uniform sintering and very good reliability under temperature cycle and thermal shock conditions.