Electrical and mechanical parameters of the module remain the same in spite of the necessary changes involved. As a result there is no need for recertification and the qualification scope is minimised. Pricing has also been maintained; the IHM-B Enhanced modules will go into volume production in August 2014.
The significantly longer life time of the IHM-B Enhanced modules is based on two central modifications. A newly implemented manufacturing technology enables more robust bond wire connections. This increases the resilience of the module components in power cycling associated with switching. The power cycling behaviour of the IHM-B Enhanced has improved by a factor of two compared to the previous model.
Secondly, the thermal conductivity of the IHM-B Enhanced is increased by the combination of an aluminum silicon carbide (AlSiC) base plate with aluminum nitride (AlN) substrates. Depending on the topology used, the thermal resistivity drops by 16 – 18%: for example, with a 2400A single switch module this means an improvement from 9.3 K/kW (IHM-B) to only 7.8 K/kW (IHM-B Enhanced). Significantly better dissipation of heat generated during operation of the module relieves in particular components susceptible to heat, such as chips and bond wires.
The new IHM-B Enhanced modules are available in the Single Switch, Chopper, Chopper with Inverted Diode and Dual-Diode topologies. In the IHM product portfolio, modules of the 1700V voltage class will be upgraded first, in the 800A to 3600A range. This conversion is to be completed by August 2014.