FLIP CHIP PACKAGE FOR DRAM WITH TWO UNDERFILL MATERIALS

摘要

A microelectronic package can include a substrate having a first surface and a plurality of substrate contacts at the first surface and a microelectronic element having a front surface and contacts arranged within a contact-bearing region of the front surface. The contacts of the microelectronic element can face the substrate contacts and can be joined thereto. An underfill can be disposed between the substrate first surface and the contact-bearing region of the front surface of the microelectronic element. The underfill can reinforce the joints between the contacts and the substrate contacts. A joining material can bond the substrate first surface with the front surface of the microelectronic element. The joining material can have a Young's modulus less than 75% of a Young's modulus of the underfill.