High voltage IGBT modules are used in high power applications including traction (tramways/trains), heavy-duty drives, transmission and distribution and renewables such as in wind-power generation and conversion. Many of these applications are subject to harsh environmental conditions and in most cases, the inverter cabinets do not shield the power electronics, including the IGBT modules from such conditions. As an example, IGBT modules can be for instance subject to increased humidity levels. Also, the inverter is not always running under full load conditions and can be in idle or running in partial load which means that the temperature can rise or drop relatively fast. Due to that, moisture can penetrate into the IGBT modules while the train is stopped for long periods of time and there are no higher temperature levels to drive out moisture from the modules. Another aspect is that condensation can appear while having a temperature drop during operation, which can lead to drastic changes in the material properties (e.g. dielectric properties of chip passivation and module encapsulation materials such as Si-gel). These undesirable modifications can have a negative impact on the electric field at the periphery of the semiconductor device and therefore cause increased localized stress at the chip junction termination region. Therefore, it is crucial that the materials used for the IGBT module and the design of the power semiconductor including chip termination and passivation can cope with the increased stress levels, posed by the application during commissioning as well as for the foreseen lifetime up to 30 years.
This is a companion discussion topic for the original entry at https://eepower.com/semiconductors/high-humidity-robustness-abb-s-igbts-and-diodes-abb-2039