Composite structure having a specific thermal coefficient of expansion

Claim 1

A composite structure having a linear thermal coefficient of expansion of about 5 to 12 ppm/°C and comprising a thin metallic body extended in at least one of width or length comprising two outer layers of metal of high electrical and heat conductivity sandwiching a thin, coextensive inner layer of low coefficient of thermal expansion metal, said inner layer having a multiplicity of essentially uniformly distributed paths of said metal of high electrical and heat conductivity extending therethrough and connected to and integral with said two outer layers of said metal of high electrical and heat conductivity, said composite structure being so constructed and arranged that A) the paths of said metal of high electrical and heat conductivity through said inner layer comprise about 15 to 40 volume percent of said inner layer; B) the thicknesses of said outer layers of said metal of high electrical and heat conductivity being controlled to provide thermal and electrical conductivity along said length and breadth (x-y) of said composite related to said conductivities across the thickness of (z) said composite such that and C) the overall volume fraction of said metal of high electrical and heat conductivity in said composite is such to provide a linear coefficient of thermal expansion within the aforesaid range.