A multichip integrated circuit package comprises a substrate having a flat upper surface to which is affixed one or more integrated circuit chips having interconnection pads. A polymer encapsulant completely surrounds the integrated circuit chips. The encapsulant is provided with a plurality of via openings therein to accommodate a layer of interconnection metallization. The metallization serves to connect various chips and chip pads with the interconnection pads disposed on the chips. In specific embodiments, the module is constructed to be repairable, have high I/O capability with optimal heat removal, have optimized speed, be capable of incorporating an assortment of components of various thicknesses and function, and be hermetically sealed with a high I/O count. Specific processing methods for each of the various module features are described herein, along with additional structural enhancements.