Conductive route patterning for electronic substrates

An electronic system, comprising:

• an electronic board;
• and
• an integrated circuit assembly electrically attached to the electronic board, wherein the at least one of the integrated circuit assembly and the electronic board includes a conductive route, comprising:
• a first route portion, wherein the first route portion has a first surface, an opposing second surface and at least one side surface extending between the first surface and the second surface of the first route portion;
• an etch stop structure on the first route portion, wherein the etch stop structure has a first surface and an opposing second surface and wherein the second surface of the etch stop structure abuts the first surface of the first route portion;
• a second route portion on the etch stop layer, wherein the second route portion has a first surface, an opposing second surface and at least one side surface extending between the first surface and the second surface of the second route portion and wherein the second surface of the second route portion abuts the first surface of the etch stop structure;
• and
• a passivating layer abutting the at least one side surface of the second route portion.

A method of fabricating a conductive route, comprising:

• forming a first conductive material layer;
• forming an etch stop layer on the first conductive material layer;
• forming a second conductive material layer on the etch stop layer;
• patterning an etch resist layer on the second conductive material layer;
• etching through the second conductive material layer to form a second route portion, wherein the second route portion has a first surface abutting the etch resist layer, an opposing second surface abutting the etch stop layer, and at least one side surface extending between the first surface and the second surface of the second route portion;
• forming a passivating layer abutting the at least one side surface of the second route portion;
• etching through the etch stop layer to form an etch stop structure;
• etching through the first conductive material layer to form a first route portion.