Micromagnetic latching switch packaging
Packages for a micromachined magnetic latching switch, and methods for assembling the packages are described. In one aspect, a substrate is defined by opposing first and second surfaces. A micromagnetic switch integrated circuit (IC) chip is mounted to the first surface. A contact pad on the chip is coupled to a trace on the first surface. A permanent magnet is positioned closely adjacent to the chip. A cap is attached to the first surface. An inner surface of the cap forms an enclosure to enclose the chip on the first surface. The chip can be alternatively mounted to the inner surface of the cap. The chip can be oriented in a standard or flip-chip fashion. In another aspect, a moveable micro-machined cantilever is supported by a surface of a substrate. A cap is attached to the surface. An inner surface of the cap forms an enclosure that encloses the cantilever on the surface of the substrate. A permanent magnet is positioned closely adjacent to the cantilever. An electromagnet is attached to the inner surface or an outer surface of the cap.
1. A package for a micromagnetic latching switch, comprising:
a substrate defined by opposing first and second surfaces, wherein said substrate includes a conductively filled via, wherein said via couples a trace on said first surface of said substrate to a contact pad on said second surface of said substrate;
a micromagnetic switch integrated circuit (IC) chip that is mounted to said first surface, wherein a contact pad on said chip is coupled to said trace, wherein said chip includes at least one moveable micro-machined cantilever having a magnetic material and a longitudinal axis;
a permanent magnet positioned closely adjacent to said chip, wherein said permanent magnet produces a first magnetic field which induces a magnetization in said magnetic material, said magnetization characterized by a magnetization vector pointing in a direction along said longitudinal axis of said cantilever, wherein said first magnetic field is anproximately perpendicular to said longitudinal axis;
an electromagnet producing a second magnetic field to switch said cantilever between a first stable state and a second stable state, wherein a temporary current through said electromagnet produces said second magnetic field such that a component of said second magnetic field parallel to said longitudinal axis changes direction of said magnetization vector thereby causing said cantilever to switch between said first stable state and said second stable state; and
a cap attached to said first surface, wherein an inner surface of said cap forms an enclosure to enclose said chip on said first surface.
2. The package of claim 1 , wherein said permanent magnet is attached to said inner surface of said cap.
3. The package of claim 1 , further comprising:
a bond wire that couples said contact pad on said chip to said trace.
4. The package of claim 1 , wherein said chip is flip chip mounted to said first surface.
5. The package of claim 4 , wherein said permanent magnet is attached to said chip.
6. The package of claim 1 , further comprising a solder ball attached to said solder ball pad.
7. A package for a micromagnetic latching switch, comprising:
a substrate defined by opposing first and second surfaces, wherein said substrate includes a conductively filled via, wherein said via couples a trace on said first surface of said substrate to a contact pad on said second surface of said substrate;
a cap attached to said first surface, wherein an inner surface of said cap forms an enclosure that encloses a portion of said first surface;
a micromagnetic switch integrated circuit (IC) chip that is mounted to said inner surface, wherein said chip includes at least one moveable micro-machined cantilever having a magnetic material and a longitudinal axis;
a permanent magnet positioned closely adjacent to said chip, wherein said permanent magnet produces a first magnetic field which induces a magnetization in said magnetic material, said magnetization characterized by a magnetization vector pointing in a direction along said longitudinal axis of said cantilever, wherein said first magnetic field is approximately perpendicular to said longitudinal axis;
an electromagnet producing a second magnetic field to switch said cantilever between a first stable state and a second stable state, wherein a temporary current through said electromagnet produces said second magnetic field such that a component of said second magnetic field parallel to said longitudinal axis changes direction of said magnetization vector thereby causing said cantilever to switch between said first stable state and said second stable state; and
a wire bond that couples a contact pad on said chip to said trace.
8. The package of claim 7 , wherein said permanent magnet is mounted on said first surface.
9. A package for a micromagnetic latching switch, comprising:
a substrate that has a surface;
a moveable micro-machined cantilever supported by said surface of said substrate, wherein said cantilever has a magnetic material and a longitudinal axis;
a cap attached to said surface of said substrate, wherein an inner surface of said cap forms an enclosure that encloses said cantilever on said surface of said substrate;
a permanent magnet positioned closely adjacent to said cantilever, wherein said permanent magnet produces a first magnetic field which induces a magnetization in said magnetic material, said magnetization characterized by a magnetization vector pointing in a direction along said longitudinal axis of said cantilever, wherein said first magnetic field is approximately perpendicular to said longitudinal axis; and
an electromagnet attached to said cap, wherein said electromagnet produces a second magnetic field to switch said cantilever between a first stable state and a second stable state, wherein a temporary current through said electromagnet produces said second magnetic field such that a component of said second magnetic field parallel to said longitudinal axis changes direction of said magnetization vector thereby causing said cantilever to switch between said first stable state and said second stable state.
10. The package of claim 9 , wherein said electromagnet includes:
a conductor; and
an insulator layer that insulates said conductor.
11. The package of claim 9 , wherein said permanent magnet is attached to a second surface of said substrate.
12. The package of claim 9 , wherein said electromagnet is attached to said inner surface.
13. The package of claim 9 , wherein said electromagnet is coupled to said inner surface, further comprising:
a magnetic layer formed between said inner surface and said electromagnet.
14. The package of claim 9 , wherein said electromagnet is attached to an outer surface of said cap.
15. The package of claim 14 , further comprising:
a magnetic layer formed on said electromagnet.
16. The package of claim 1 , wherein said chip includes said electromagnet.
17. The package of claim 1 , wherein said contact pad on said second surface of said substrate is a solder ball pad.
18. The package of claim 7 , wherein said chip includes said electromagnet.
19. The package of claim 7 , wherein said contact pad on said second surface of said substrate is a solder ball pad.