Fuel cell stack assembly with pressure balanced load mechanism and assembly method

A fuel cell stack assembly includes a fuel cell stack wherein a plurality of fuel cell cassettes is coupled together by a joining material. A spring strap is coupled to the fuel cell stack in a manner effective to apply a first compressive force to the fuel cell stack. A first load distribution plate is located intermediate the fuel cell stack and the spring strap. The first load distribution plate is configured to distribute the first compressive force over the fuel cell stack in a manner effective to normalize the first compressive force on the joining material. A diaphragm is configured to define a cavity and is configured to apply a second compressive force to the fuel cell stack dependent on a cavity pressure of oxidant within the cavity. The cavity pressure is dependent upon an oxidant pressure of oxidant provided to the fuel cell stack.