MEMS packaging method for enhanced EMI immunity using flexible substrates

• US 20070013052A1
• Filed: 01/17/2006
• Published: 01/18/2007
• Est. Priority Date: 07/15/2005
• Status: Active Grant

• Current Assignee: Shandong Gettop Acoustic Company Limited (Weifang Gaoke Electronic Company Limited)
• Original Assignee: Silicon Matrix Pte., Ltd.
• Inventors: Zhe, Wang, Yubo, Miao
• Granted Patent: US 7,692,288 B2
• Time in Patent Office: Days
• US Class Current: 257/704
• CPC Class Codes: B81B 2201/0257 Microphones or microspeakers
• CPC Class Codes: B81C 1/0023 Packaging together an electronic processing unit die and a micromechanical structure die MEMS packages B81B7/0032; MEMS packaging processes B81C1/00261
• CPC Class Codes: B81C 1/00309 suitable for fluid transfer from the MEMS out of the package or vice versa, e.g. transfer of liquid, gas, sound
• CPC Class Codes: H01L 2224/05554 being square
• CPC Class Codes: H01L 2224/05599 Material
• CPC Class Codes: H01L 2224/32225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/45099 Material
• CPC Class Codes: H01L 2224/451 with a principal constituent of the material being a metal or a metalloid, e.g. boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), tellurium (Te) and polonium (Po), and alloys thereof
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48137 the bodies being arranged next to each other, e.g. on a common substrate
• CPC Class Codes: H01L 2224/48227 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/49109 outside the semiconductor or solid-state body
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 23/057 the leads being parallel to the base
• CPC Class Codes: H01L 23/5387 Flexible insulating substrates H01L23/5388 takes precedence
• CPC Class Codes: H01L 23/552 Protection against radiation, e.g. light or electromagnetic waves
• CPC Class Codes: H01L 24/48 of an individual wire connector
• CPC Class Codes: H01L 24/49 of a plurality of wire connectors
• CPC Class Codes: H01L 24/73 Means for bonding being of different types provided for in two or more of groups H01L24/10, H01L24/18, H01L24/26, H01L24/34, H01L24/42, H01L24/50, H01L24/63, H01L24/71
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00012 : Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00014 : the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/01019 : Potassium [K]
• CPC Class Codes: H01L 2924/01077 : Iridium [Ir]
• CPC Class Codes: H01L 2924/01078 : Platinum [Pt]
• CPC Class Codes: H01L 2924/01079 : Gold [Au]
• CPC Class Codes: H01L 2924/01087 : Francium [Fr]
• CPC Class Codes: H01L 2924/01322 : Eutectic Alloys, i.e. obtained by a liquid transforming into two solid phases
• CPC Class Codes: H01L 2924/07802 : not being an ohmic electrical conductor
• CPC Class Codes: H01L 2924/09701 : Low temperature co-fired ceramic [LTCC]
• CPC Class Codes: H01L 2924/14 : Integrated circuits
• CPC Class Codes: H01L 2924/1433 : Application-specific integrated circuit [ASIC]
• CPC Class Codes: H01L 2924/1461 : MEMS
• CPC Class Codes: H01L 2924/15151 : the die mounting substrate comprising an aperture, e.g. for underfilling, outgassing, window type wire connections
• CPC Class Codes: H01L 2924/15311 : being a ball array, e.g. BGA
• CPC Class Codes: H01L 2924/16152 : Cap comprising a cavity for hosting the device, e.g. U-shaped cap
• CPC Class Codes: H01L 2924/181 : Encapsulation
• CPC Class Codes: H01L 2924/19041 : being a capacitor
• CPC Class Codes: H01L 2924/19105 : in a side-by-side arrangement on a common die mounting substrate
• CPC Class Codes: H01L 2924/3025 : Electromagnetic shielding

Abstract

A MEMS package and methods for its embodiment are described. The MEMS package has at least one MEMS device mounted on a flexible and foldable substrate. A metal cap structure surrounds the at least one MEMS device wherein an edge surface of the metal cap structure is attached to the flexible substrate and wherein a portion of the flexible substrate is folded under itself thereby forming the MEMS package. A meshed metal environmental hole underlying the at least one MEMS device provides enhanced EMI immunity.

Claims

1. A MEMS package comprising:

at least one MEMS device;

a folded flexible substrate having at least one metal layer on which said at least one MEMS device is mounted;

a metal cap structure surrounding said at least one MEMS device wherein an edge surface of said metal cap structure is attached and electrically connected to said at least one metal layer in said folded flexible substrate;

a meshed metal layer in said folded flexible substrate and underlying said at least one MEMS device; and

an environmental hole covered with said meshed metal layer in said folded flexible substrate.

2. The package according to claim 1 wherein said flexible substrate comprises a core film with a copper layer on a top side of said core film or copper layers on both sides of said core film wherein said core film comprises polyimide, polyethylene polyimide, poly tetra fluoro ethylene, or liquid crystal polymer.

3. The package according to claim 1 wherein said at least one metal layer in said flexible substrate comprises a copper metal layer with a surface finish of nickel and gold.

4. The package according to claim 1 wherein said metal cap structure encapsulates said at least one MEMS device and may comprise a copper, a copper alloy, an aluminum alloy, an iron alloy with solderable metal finish, a plastic with a metal finish formed by either electroless plating or painting, or a conductive composite material formed by either injection molding or transfer molding.

5. The package according to claim 1 wherein said flexible substrate further comprises two metal layers thereon, wherein said flexible substrate is folded under itself so that one of said two metal layers lies below said at least one MEMS device and wherein said metal layer below said at least one MEMS device, said metal cap, and said meshed metal layer together provide EMI shielding of said at least one MEMS device.

6. The package according to claim 1 wherein said metal cap structure is attached to one portion of said flexible substrate at said edge surface of said metal cap structure by a conductive adhesive, or soldering, or a combination of conductive adhesive or soldering and a non-conductive adhesive, or by a combination of a conductive adhesive or solder with a non-conductive adhesive.

7. The package according to claim 1 further comprising one or more electronic components located on said flexible substrate and within said metal cap structure.

8. The package according to claim 7 further comprising wire bonding connections among said one or more electronic components, said at least one MEMS device, and said flexible substrate.

9. The package according to claim 1 wherein said environmental hole permits interaction between said MEMS device and the environment outside said package.

10. A MEMS package comprising:

at least one MEMS device;

a flexible substrate having at least one metal layer and a rigid conductive plate wherein said at least one MEMS device is mounted on said flexible substrate and wherein a portion of said flexible substrate is folded and attached to said rigid conductive plate;

a plurality of via holes in said flexible substrate;

a metal cap structure surrounding said at least one MEMS device wherein an edge surface of said metal cap structure is attached and electrically connected to said metal layer in said flexible substrate and to said rigid conductive plate through said via holes in said flexible substrate;

a meshed metal layer in said folded flexible substrate and underlying said at least one MEMS device; and

an environmental hole in both said folded flexible substrate and said rigid conductive plate wherein said environmental hole is covered with said meshed metal layer.

11. The package according to claim 10 wherein said flexible substrate comprises a core film with a copper layer on a top side of said core film or copper layers on both sides of said core film wherein said core film comprises polyimide, polyethylene polyimide, poly tetra fluoro ethylene, or liquid crystal polymer.

12. The package according to claim 10 wherein said at least one metal layer in said flexible substrate comprises a copper metal layer with a surface finish of nickel and gold.

13. The package according to claim 10 wherein said metal cap structure encapsulates said at least one MEMS device and may comprise a copper, a copper alloy, an aluminum alloy, an iron alloy with solderable metal finish, a plastic with a metal finish formed by either electroless plating or painting, or a conductive composite material formed by either injection molding or transfer molding.

14. The package according to claim 10 further comprising one or more electronic components located on said flexible substrate and within said metal cap structure.

15. The package according to claim 14 further comprising wire bonding connections among said one or more electronic components, said at least one MEMS device, and said flexible substrate.

16. The package according to claim 10 wherein said environmental hole permits interaction between said MEMS device and the environment outside said package.

17. The package according to claim 10 wherein said rigid conductive plate comprises a metal plate or a FR-4 PCB.

18. The package according to claim 10 wherein said metal cap structure is attached and electrically connected to said at least one metal layer in said flexible substrate and a top portion of said rigid conductive plate through said via holes in said flexible substrate at said edge surface of said metal cap structure by a conductive adhesive, or soldering, or a combination of conductive adhesive or soldering and a non-conductive adhesive, or by a combination of a conductive adhesive or solder with a non-conductive adhesive.

19. The package according to claim 10 wherein said metal cap structure, said at least one metal layer in said flexible substrate, and said rigid conductive plate together provide EMI shielding of said at least one MEMS device.

20. A MEMS package comprising:

at least one MEMS device;

a flexible substrate having at least one metal layer on which said at least one MEMS device is mounted;

a rigid conductive plate attached to said flexible substrate and underlying said at least one MEMS device wherein a portion of said flexible substrate is folded and attached to said rigid conductive plate;

a passage hole in said flexible substrate underlying said at least one MEMS device;

a plurality of via holes in said flexible substrate;

a metal cap structure surrounding said at least one MEMS device wherein an edge surface of said metal cap structure is attached and electrically connected to said folded flexible substrate and to said rigid conductive plate through said via holes in said flexible substrate;

at least one punched opening in said rigid conductive plate and underlying said passage hole in said flexible substrate; and

an environmental hole in said metal cap structure.

21. The package according to claim 20 wherein said flexible substrate comprises a core film with a copper layer on a top side of said core film or copper layers on both sides of said core film wherein said core film comprises polyimide, polyethylene polyimide, poly tetra fluoro ethylene, or liquid crystal polymer.

22. The package according to claim 20 wherein said at least one metal layer in said flexible substrate comprises a copper metal layer with a surface finish of nickel and gold.

23. The package according to claim 20 wherein said metal cap structure encapsulates said at least one MEMS device and may comprise a copper, a copper alloy, an aluminum alloy, an iron alloy with solderable metal finish, a plastic with a metal finish formed by either electroless plating or painting, or a conductive composite material formed by either injection molding or transfer molding.

24. The package according to claim 20 further comprising one or more electronic components located on said flexible substrate and within said metal cap structure.

25. The package according to claim 24 further comprising wire bonding connections among said one or more electronic components, said at least one MEMS device, and said flexible substrate.

26. The package according to claim 20 wherein said environmental hole permits interaction between said MEMS device and the environment outside said package.

27. The package according to claim 20 wherein said rigid conductive plate comprises a metal plate or a FR-4 PCB.

28. The package according to claim 20 wherein said metal cap structure is attached and electrically connected to said at least one metal layer in said flexible substrate and a top portion of said rigid conductive plate through said via holes in said flexible substrate at said edge surface of said metal cap structure by a conductive adhesive, or soldering, or a combination of conductive adhesive or soldering and a non-conductive adhesive, or by a combination of a conductive adhesive or solder with a non-conductive adhesive.

29. The package according to claim 20 wherein said metal cap structure, and said at least one metal layer in said flexible substrate together provide EMI shielding of said at least one MEMS device.

30. A method for fabricating a metal meshed hole in a MEMS package comprising:

providing a substrate comprising a flexible material having a metal layer thereover;

patterning said metal layer to form a meshed metal hole; and

removing said flexible material not covered by said patterned metal layer to complete fabrication of said meshed metal hole.

31. The method according to claim 30 wherein said removing said flexible material comprises laser burning.

32. The method according to claim 30 wherein a bottom metal layer underlies said flexible material, further comprising:

patterning said bottom metal layer to form an opening underlying said meshed metal hole.