Magnetic Field Sensors and Methods for Fabricating the Magnetic Field Sensors
AssigneeAllegro MicroSystems, LLC
InventorsVirgil Ararao, Nirmal Sharma, Raymond W. Engel, Jay Gagnon, John Sauber, William P. Taylor, Elsa Kam-Lum
Life of this patent
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Abstract
Magnetic field sensors and associated methods of manufacturing the magnetic field sensors include molded structures to encapsulate a magnetic field sensing element and an associated die attach pad of a lead frame and to also encapsulate or form a magnet or a flux concentrator.
Claims21
A method of fabricating a magnetic field sensor, comprising:
- attaching a magnetic field sensor circuit die to a first surface of a die attach pad of a lead frame, the die attach pad having the first surface and a second opposing surface;
- forming a molded capsule enclosing the magnetic field sensor circuit die, wherein the molded capsule includes a cavity having an inner cavity surface, wherein a portion of the inner cavity surface is proximate to the second surface of the die attach pad, and wherein the cavity has a shape capable of retaining a liquid;
- placing a magnet into the cavity and proximate to the second opposing surface of the die attach pad;
- placing a liquid encapsulant into the cavity proximate to the magnet;
- and
- curing the liquid encapsulate to a solid condition to retain the magnet.
8-14. (canceled)
A method of fabricating an integrated sensor, comprising:
- attaching a magnetic field sensor circuit die to a first surface of a die attach pad of a lead frame, the die attach pad having the first surface and a second opposing surface;
- forming a molded capsule comprising of a mold compound enclosing the magnetic field sensor circuit die, wherein the molded capsule covers the second surface of the die attach pad with the mold compound forming an insulating layer over the second surface of the die attach pad;
- placing a magnet over the insulating layer;
- and
- forming a molded enclosure surrounding the magnet.
23-30. (canceled)
A method of fabricating a magnetic field sensor, comprising:
- attaching a magnetic field sensor circuit die to a first surface of a die attach pad of a lead frame, the die attach pad having the first surface and a second opposing surface;
- forming a molded capsule enclosing the magnetic field sensor circuit die, wherein the molded capsule includes a cavity having an inner cavity surface, wherein a portion of the inner cavity surface is proximate to the second surface of the die attach pad, and wherein the cavity has a shape capable of retaining a liquid;
- placing a liquid material into the cavity and proximate to the second opposing surface of the die attach pad, wherein the liquid material is filled with ferromagnetic particles to either generate a magnetic field or to concentrate a magnetic field;
- and
- curing the liquid material.
(canceled)
A method of fabricating an integrated sensor, comprising:
- attaching a magnetic field sensor circuit die to a first surface of a die attach pad of a lead frame, the die attach pad having the first surface and a second opposing surface;
- forming a molded capsule comprised of a mold compound enclosing the magnetic field sensor circuit die, wherein the molded capsule covers the second surface of the die attach pad forming an insulating layer over the second surface of the die attach pad with the mold compound;
- and
- forming a molded structure proximate to the second surface of the die attach pad. wherein the molded structure is filled with ferromagnetic particles to either generate a magnetic field or to concentrate a magnetic field.
(canceled)
Dependencies are inferred from the claim text.