International Business Machines Corporation
Functional stiffener that enables land grid array interconnections and power decoupling

Abstract:

An exemplary assembly includes a top circuit substrate; a bottom circuit assembly that underlays the top circuit substrate and is attached to the top circuit substrate by an adhesive layer as a stiffener, the adhesive layer, and a plurality of conductive balls. The top circuit substrate includes a plurality of upper vias that extend through the top circuit substrate. The bottom circuit assembly includes a plurality of lower vias that extend through the bottom circuit assembly. The adhesive layer includes internal connections that electrically connect the upper vias to the lower vias. The conductive balls are housed in the lower vias. The bottom circuit assembly has an elastic modulus at least six times the elastic modulus of the top circuit substrate, and has a coefficient of thermal expansion at least two times the coefficient of thermal expansion of the top circuit substrate.