Method of manufacturing a double sided flex circuit for a disk drive wherein a first side lead provides an etching mask for a second side lead

1. A method of manufacturing a flex circuit for a disk drive, the disk drive comprising a disk, a head actuated radially over the disk, and control circuitry, wherein the flex circuit is for electrically coupling the head to the control circuitry and comprises a substrate, the method comprising:

etching an electrical coating applied to a first side of the substrate to form a first electrical lead;

irradiating the first side of the substrate with radiation such that the first electrical lead masks the radiation from passing through the substrate to prevent curing of a photoresist applied to a second side of the substrate, wherein the photoresist is formed into an uncured photoresist and a cured photoresist on the second side of the substrate;

removing the uncured photoresist from the second side of the substrate to form a groove; and

filling the groove with electrically conductive material to form a second electrical lead.

2. The method as recited in claim 1 , wherein the first electrical lead is substantially aligned with the second electrical lead such that the substrate forms a capacitive dielectric.

3. The method as recited in claim 1 , wherein the substrate comprises a polyimide.

4. The method as recited in claim 3 , wherein the polyimide is sufficiently transparent to pass the radiation.

5. The method as recited in claim 4 , wherein the radiation comprises ultraviolet light.

6. The method as recited in claim 4 , wherein the radiation comprises visible light.