Magnetic shielding of MRAM chips
An apparatus comprising a magnetically shielded MRAM chip and a method of manufacturing the same. The apparatus includes an MRAM module and a protective cover. The MRAM module includes a circuit board and a memory chip attached to the circuit board, the memory chip containing magnetoresistive random access memory (MRAM) cells. The protective cover includes a magnetic shielding material and at least partially encloses the memory chip. In another embodiment, the protective cover shields the memory chip without shielding at least a portion of the circuit board.
1 . An apparatus comprising:
a memory module comprising:
a circuit board; and
a memory chip attached to the circuit board, the memory chip comprising magnetoresistive random access memory (MRAM) cells; and
a protective cover at least partially enclosing the memory chip, the protective cover comprising magnetic shielding material.
2 . The apparatus of claim 1 wherein the protective cover reduces a magnitude of magnetic fields at the memory chip by about 20 percent relative to the memory chip not shielded by the protective cover.
3 . The apparatus of claim 2 wherein the protective cover reduces a magnitude of magnetic fields at the memory chip by about 50 percent relative to the memory chip not shielded by the protective cover.
4 . The apparatus of claim 1 wherein the protective cover comprises Mu-metal.
5 . The apparatus of claim 1 wherein the protective cover comprises about 77 percent nickel, and about 15 to 16 percent iron.
6 . The apparatus of claim 1 wherein the protective cover comprises material containing magnetic shielding particles.
7 . The apparatus of claim 1 wherein the protective cover has a composite structure comprising more than one layer.
8 . The apparatus of claim 1 further comprising an electrical insulating layer between the protective cover and at least one of the memory chip and/or the circuit board.
9 . The apparatus of claim 8 wherein the electrical insulating layer comprises air.
10 . The apparatus of claim 1 wherein the circuit board of the MRAM module has a first end having contact pads, a second end, a third end, a fourth end, a first side and a second side opposite the first side, wherein the protective cover is open at the first end.
11 . The apparatus of claim 10 wherein the protective cover at least partially covers the first and the second sides and wraps around the second, third and fourth ends.
12 . The apparatus of claim 11 wherein the protective cover has openings in at least one of the second, third, or fourth ends or the first or second sides.
13 . The apparatus of claim 10 wherein the protective cover does not extend to at least one of the first, second, third or fourth ends.
14 . The apparatus of claim 13 further comprising an additional protective cover on the second side of the circuit board, the additional protective cover being formed of a magnetic shielding material.
15 . The apparatus of claim 14 wherein the additional protective cover is coupled to the protective cover through the magnetic shielding material.
16 . The apparatus of claim 14 further comprising an additional insulating layer between the additional protective cover and the second side of the circuit board.
17 . The apparatus of claim 13 further comprising an extra protective cover at least partially enclosing an additional memory chip, the extra protective cover comprising a magnetic shielding material.
18 . An apparatus comprising:
a semiconductor chip with MRAM cells formed therein; and
a protective cover formed over at least two surfaces of the semiconductor chip, the protective cover comprising a magnetic shielding material.
19 . The apparatus of claim 18 wherein at least one edge of the protective cover wraps around a corner of the semiconductor chip.
20 . The apparatus of claim 18 wherein the protective cover comprises a top portion and a bottom portion.
21 . A method of manufacturing a memory device, the method comprising attaching a protective cover to a circuit board, wherein the circuit board has a memory chip comprising MRAM cells, wherein the protective cover at least partially encloses the memory chip after the attaching.
22 . The method of claim 21 wherein the attaching comprises crimping a portion of the protective cover.
23 . The method of claim 21 wherein the attaching comprises molding the protective cover onto the circuit board.
24 . The method of claim 21 wherein the attaching comprises bending and shaping the protective cover.