Bilayer coil insulation for magnetic write heads to minimize pole recession
View Patent ↗A magnetic write head for use in a data recording system having first and second magnetic pole, the first pole having a P1 pedestal. An electrically conductive coil passes through a space between the first and second poles for inducing a magnetic flux through the yoke formed by the first and second poles. A bi-layer insulation layer disposed between the poles includes a layer of photoresist for preventing voids and a layer of alumina formed thereover to provide a structural brace to prevent recession of the P1 pedestal during manufacturing operations such as soda blast.
1. A magnetic write head, comprising:
a first magnetic pole;
a magnetic pedestal formed over and magnetically connected with the first pole in a pole tip region, the pedestal having an air bearing surface and a back end opposite the air bearing surface;
a second magnetic pole formed above the first magnetic pole and magnetically connected with the first pole by a magnetic back gap structure disposed opposite the pole tip region;
an electrically conductive coil having turns passing between the first and second poles between the pedestal and the back gap structure;
a non-magnetic write gap disposed between the magnetic pedestal and the second pole;
a layer of photoresist material formed over the first pole, a portion of the photoresist material being disposed between the turns of the coil, and a portion of the photoresist material being disposed between the coil and the pedestal; and
a layer of Al 2 O 3 (alumina) formed over the photoresist material, the layer of alumina abutting the back end of the pedestal and contacting at least one of the turns of the coil;
wherein the layer of alumina is partially interspersed between the turns of the coil.
2. A write head as in claim 1 wherein:
the coil has a first turn located closer to the pedestal than any other turn and a second turn located adjacent to the first turn;
the layer of alumina extends from the pedestal to the first turn of the coil, contacting the first turn of the coil; and
the layer of alumina terminates at a location between the pedestal and first turn of the coil.
3. A write head as in claim 1 wherein the layer of alumina extends from the back end of the pedestal, contacts a turn of the coil and terminates at a point prior to reaching the back gap.
4. A magnetic write head, comprising:
a first magnetic pole;
a magnetic pedestal formed over and magnetically connected with the first pole in a pole tip region, the pedestal having an air bearing surface and a back end opposite the air bearing surface;
a second magnetic pole formed above the first magnetic pole and magnetically connected with the first pole by a magnetic back gap structure disposed opposite the pole tip region;
an electrically conductive coil having turns passing between the first and second poles between the pedestal and the back gap structure;
a non-magnetic write gap disposed between the magnetic pedestal and the second pole;
a layer of photoresist material formed over the first pole, a portion of the photoresist material being disposed between the turns of the coil, and a portion of the photoresist material being disposed between the coil and the pedestal; and
a layer of Al 2 O 3 (alumina) formed over the photoresist material, the layer of alumina abutting the back end of the pedestal and contacting at least one of the turns of the coil;
wherein the layer of photoresist material, comprises;
a coil insulation layer, comprising photoresist having portions disposed between the turns of the coil, and having a downward sloping portion disposed between the coil and the pedestal; and
a fill layer comprising photoresist, disposed between the coil insulation layer and the pedestal portion.
5. A write head as in claim 4 wherein at least a portion of the layer of alumina is formed over the fill layer.
6. A magnetic write head, comprising:
a first magnetic pole;
a magnetic pedestal formed over and magnetically connected with the first pole in a pole tip region, the pedestal having an air bearing surface rid a back end opposite the air bearing surface;
a second magnetic pole formed above the first magnetic pole and magnetically connected with the first pole by magnetic back gap structure disposed opposite the pole tip region;
an electrically conductive coil having turns passing between the first and second poles between the pedestal and the back gap structure;
a non-magnetic write gap disposed between the magnetic pedestal and the second pole;
a layer of photoresist material formed over the first pole, a portion of the photoresist material being disposed between the turns of the coil, and a portion of the photoresist material being disposed between the coil and the pedestal; and
a layer of Al 2 O 3 (alumina) formed over the photoresist material, the layer of alumina abutting the back end of the pedestal and contacting at least one of the turns of the coil;
wherein the back end of the pedestal has a surface area, and wherein the layer of alumina abuts about half of the surface area of the back end of the pedestal.
7. A magnetic write head, comprising:
a first magnetic pole;
a magnetic pedestal formed over and magnetically connected with the first pole in a pole tip region, the pedestal having an air bearing surface and a back end opposite the air bearing surface;
a second magnetic pole formed above the first magnetic pole and magnetically connected with the first pole by a magnetic back gap structure disposed opposite the pole tip region;
an electrically conductive coil having turns passing between the first and second poles between the pedestal and the back gap structure;
a non-magnetic write gap disposed between the magnetic pedestal and the second pole;
a layer of photoresist material formed over the first pole, a portion of the photoresist material being disposed between the turns of the coil, and a potion of the photoresist material being disposed between the coil and the pedestal; and
a layer of Al 2 O 3 (alumina) formed over the photoresist material, the layer of alumina abutting the back end of the pedestal and contacting at least one of the turns of the coil;
wherein the layer wherein portions of the alumina layer extend into a space between the turns of the coil and wherein those portions of the alumina layer extend into the spaces between the coils by a vertical distance X that is no more than ½ a distance Y measured horizontally between the turns of the coil.