This paper describes the electronic circuit packaging techniques employed in the Signal Conditioning Electronic Assembly (SCEA) which is a critical part of the Project Apollo Lunar Module instrumentation. Mission and equipment requirements are reviewed and the nature of the SCEA circuits is described. Lunar Module packaging concepts, insofar as they affect the SCEA, are discussed. Design problems and the design method employed are covered and hardware descriptions are given for SCEA plug-in subassemblies and their constituent welded cordwood circuit modules. Significant features of the design are: extremely rugged subassemblies, very high welded module part densities, and new microminiature transformer design and fabrication techniques.