An implantable pulse generator (IPG) is disclosed herein. The IPG may be very small compared to most IPGs and may have a volume on the order of about 3 cm3. The IPG has a separate battery compartment and electronics compartment that may be joined together by laser welding, for example. The combined battery compartment/electronics compartment is then enclosed or partially enclosed within a rigid shell made of a polymeric material. The shell provides structural stability and support for the IPG and provides a barrier against puncturing the IPG. The IPG can then be overmolded with a soft coating material such as silicone. The overmolding provides an additional layer of protection against leakage of non- biocompatible components and also enhances the comfort of the IPG. An electrode assembly may be joined to the IPG prior to overmolding, in which case the overmolding secures the electrode assembly to the IPG.
