In {HEAD ~ accordance} with {TAIL ~ the invention}, a low dielectric constant insulation material is provided which comprises a porous insulation layer, preferably sandwiched between non porous upper and lower insulation layers 
In { HEAD ~ accordance } with { TAIL ~ the invention } , a low dielectric constant insulation material is provided which comprises a porous insulation layer , preferably sandwiched between non porous upper and lower insulation layers
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