We report on the design, modeling, and construction of far-infrared focal plane array modules for the Space Infrared Telescope Facility (SIRTF). The modules consist of 4 × 32 detector elements, readout electronics, and interconnections. The modules, which are of Z- plane architecture, may be stacked to produce imaging arrays of at least 32 × 32 format. These arrays are the largest available operating in the wavelength range 50 - 120 μm. The design takes advantage of the Hughes CRC-696 readout which was specifically developed for use with far-infrared photoconductive detectors. Since the readouts have excellent performance at temperatures below 2 K, a simplified construction concept using the proven interconnection methods of wire boding and multilayer ceramic boards are used. We report on additional design considerations such as minimization of parasitic capacitance at the input node and accommodation of thermal annealing of the detectors.