US 9,812,588 B2
Magnetic field sensor integrated circuit with integral ferromagnetic material
Ravi Vig, Bow, NH (US); William P. Taylor, Amherst, NH (US); Paul David, Bow, NH (US); P. Karl Scheller, Bow, NH (US); and Andreas P. Friedrich, Metz-Tessy (FR)
Assigned to Allegro Microsystems, LLC, Worcerter, MA (US)
Filed by Allegro Microsystems, LLC, Worcester, MA (US)
Filed on Jan. 24, 2013, as Appl. No. 13/748,999.
Application 13/748,999 is a continuation in part of application No. 13/424,618, filed on Mar. 20, 2012.
Prior Publication US 2013/0249029 A1, Sep. 26, 2013
This patent is subject to a terminal disclaimer.
Int. Cl. G01R 33/06 (2006.01); H01L 29/82 (2006.01); G01R 33/00 (2006.01)
CPC H01L 29/82 (2013.01) [G01R 33/0047 (2013.01); G01R 33/0052 (2013.01); G01R 33/06 (2013.01); H01L 2224/45147 (2013.01); H01L 2224/48247 (2013.01)] 15 Claims
OG exemplary drawing
 
1. A magnetic field sensor comprising:
a lead frame having a first surface and a second opposing surface;
a semiconductor die having a first surface in which a magnetic field sensing element is disposed and a second opposing surface attached to the first surface of the lead frame;
a non-conductive mold material enclosing the die and at least a portion of the lead frame; and
a ferromagnetic mold material secured to a portion of the non-conductive mold material, wherein the ferromagnetic mold material comprises a central aperture having a surface extending from the non-conductive mold material to an outer peripheral surface of the ferromagnetic mold material, wherein the surface of the central aperture comprises a bend at an intermediate location such that the surface of the central aperture has a first slope from the non-conductive mold material to the bend and a second slope different than the first slope from the bend to the outer peripheral surface of the ferromagnetic mold material.