Patent ID: 8142878

Claim:
An apparatus comprising: a substrate including a core material, the core material formed with a filler including aluminum trihydrate and a secondary filler material including a clay material, wherein the secondary filler material can trap water released by the aluminum trihydrate at a solder reflow temperature to which the substrate is subjected, wherein (a) the secondary filler material is to prevent water of hydration of a secondary decomposition reaction from delaminating the core material and (b) the substrate includes a plurality of vias extending through the core material to contact at least one conductive layer of a first plurality of build up layers on a first side of the core material and at least one conductive layer of a second plurality of build up layers on a second side of the core material, and a plurality of solder bumps, wherein the solder bumps are formed by a solder reflow process that occurs at the solder reflow temperature, and (c) the core material is halogen free.