Wafer with liquid molding compound and post-passivation interconnect

A die comprising:

• a substrate;
• a metal pad over the substrate;
• a passivation layer comprising a portion covering edge portions of the metal pad;
• a polymer layer over the passivation layer;
• a Post-Passivation Interconnect (PPI) comprising a copper-containing material as a top surface portion, wherein the copper-containing material comprises:
• a first portion over the polymer layer;
• and
• a second portion extending into the polymer layer to electrically couple to the metal pad;
• a solder region over and in physical contact with the copper-containing material of the PPI;
• and
• an encapsulating material in physical contact with both the solder region and the PPI, wherein the encapsulating material comprises a filler therein, and particles in the filler have sizes smaller than widths of the PPI, with the widths being viewed from a top view of the PPI, wherein the encapsulating material has a glass transition temperature higher than about 150° C., and the glass transition temperature is an inherent property of the encapsulating material, and wherein the encapsulating material has a flexural modulus between about 2 GPa and about 10 GPa, with the flexural modulus being measured at 25° C.

A die comprising:

• a polymer layer;
• a Post-Passivation Interconnect (PPI) comprising a first portion over the polymer layer, and a second portion extending into the polymer layer, wherein the PPI comprises a copper-containing material;
• a solder region over and in physical contact with the copper-containing material of the PPI;
• and
• an encapsulating material in physical contact with the solder region, the copper-containing material, and the polymer layer, wherein an upper portion of the solder region protrudes out of the encapsulating material, and the encapsulating material has a flexural modulus between about 2 GPa and about 10 GPa, with the flexural modulus being measured at 25° C., and wherein the encapsulating material has a glass transition temperature higher than about 150° C., and the glass transition temperature is an inherent property of the encapsulating material.