A method for a down-hole cable is provided. The down-hole cable includes an insulated conductor portion. A filler layer abuts and encapsulates the insulated conductor portion, wherein the filler layer is substantially formed with a foamed fluoropolymer. An armor shell is applied to the exterior of the foamed fluoropolymer filler layer.

In an insulated wire including a conductor formed into a long shape and an insulation film formed by stacking at least one insulating layer covering a circumference of the conductor, the insulating layer includes a porous region and a resin region. The porous region is formed of a resin and multiple voids, and the resin region is formed of the resin. In the insulating layer, a boundary surface is not provided between a first boundary surface located on a radially inner side and a second boundary surface located on a radially outer side, and the porous region and the resin region are arranged in this order from the first boundary surface toward the second boundary surface.

A method for a down-hole cable is provided. The down-hole cable includes an insulated conductor portion. A filler layer abuts and encapsulates the insulated conductor portion, wherein the filler layer is substantially formed with a foamed fluoropolymer. An armor shell is applied to the exterior of the foamed fluoropolymer filler layer.

A system and method for a down-hole cable is provided. The down-hole cable includes an insulated conductor portion. A filler layer abuts and encapsulates the insulated conductor portion, wherein the filler layer is substantially formed with a foamed fluoropolymer. An armor shell is applied to the exterior of the foamed fluoropolymer filler layer.