Abstract: A thermal and shock resistant data recorder assembly as an outer container (1) containing an inner container (2) which in turn houses one or more data recorder elements (3). The elements (3) which have a thin conformal coating thereon are encapsulated in an innermost cavity (4) of the inner container (2) in an Ester wax material which absorbs heat when changing from a solid to a liquid. An outermost cavity (8) surrounds the innermost cavity (4) in the container (2) and in turn contains a first insulating material which gives off water vapor when heated to absorb heat. Surrounding the inner container (2) in the outer container (1) is a second insulating material. The Ester wax material is enabled to leak when liquid into the outer container and from thence, if necessary, to the exterior of the outer container. This permits pressure equalization. The first insulating material is provided with a fusible material plug which melts under heat and allows the vapor to escape to the exterior of the assembly.