Patent ID: 8373282

Claim:
A structure comprising: a semiconductor substrate; a metal pad over the semiconductor substrate; a passivation layer over the semiconductor substrate and comprising a portion over the metal pad; a first polyimide layer over the passivation layer, wherein the first polyimide layer has a first thickness and a first Young's modulus; a post-passivation interconnect (PPI) comprising a first portion over the first polyimide layer, and a second portion extending into the first polyimide layer and electrically coupled to the metal pad; and a second polyimide layer over the PPI, wherein the second polyimide layer has a second thickness and a second Young's modulus, and wherein at least one of a thickness ratio and a Young's modulus ratio is greater than 1.0, with the thickness ratio being equal to the ratio of the first thickness to the second thickness, and the Young's modulus ratio being equal to the ratio of the second Young's modulus to the first Young's modulus.