Microelectronic assembly comprising dielectric structures with different young modulus and having reduced mechanical stresses between the device terminals and external contacts

Abstract

A microelectronic assembly may include a substrate containing a dielectric element having first and second opposed surfaces. The dielectric element may include a first dielectric layer adjacent the first surface, and a second dielectric layer disposed between the first dielectric layer and the second surface. A Young's modulus of the first dielectric layer may be at least 50% greater than the Young's modulus of the second dielectric layer, which is less than two gigapascal (GPa). A conductive structure may extend through the first and second dielectric layers and electrically connect substrate contacts at the first surface with terminals at the second surface. The substrate contacts may be joined with contacts of a microelectronic element through conductive masses, and a rigid underfill may be between the microelectronic element and the first surface. The terminals may be usable to bond the microelectronic assembly to contacts of a component external to the microelectronic assembly.