Accelerometer protected by caps applied at the wafer scale

• US 20030122227A1
• Filed: 05/06/2002
• Published: 07/03/2003
• Est. Priority Date: 01/10/2001
• Status: Active Grant

• Current Assignee: Nytell Software LLC (Intellectual Ventures LLC)
• Original Assignee: Silverbrook Research Pty Limited
• Inventors: Silverbrook, Kia
• Granted Patent: US 6,777,259 B2
• Time in Patent Office: Days
• US Class Current: 257/678
• CPC Class Codes: B29C 2035/0822 using IR radiation
• CPC Class Codes: B29C 2043/503 using ejector pins, rods
• CPC Class Codes: B29C 33/0022 Multi-cavity moulds B29C33/301 takes precedence
• CPC Class Codes: B29C 43/36 Moulds for making articles of definite length, i.e. discrete articles
• CPC Class Codes: B81B 2201/0235 Accelerometers
• CPC Class Codes: B81B 2207/056 of static structures
• CPC Class Codes: B81C 1/00269 Bonding of solid lids or wafers to the substrate
• CPC Class Codes: B81C 1/00333 Aspects relating to packaging of MEMS devices, not covered by groups B81C1/00269 - B81C1/00325
• CPC Class Codes: B81C 1/00904 Multistep processes for the separation of wafers into individual elements not provided for in groups B81C1/00873 - B81C1/00896
• CPC Class Codes: B81C 2201/034 Moulding
• CPC Class Codes: B81C 2203/0127 Using a carrier for applying a plurality of packaging lids to the system wafer
• CPC Class Codes: G01P 1/023 for acceleration measuring devices
• CPC Class Codes: G01P 15/0802 Details
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/48465 the other connecting portion not on the bonding area being a wedge bond, i.e. ball-to-wedge, regular stitch
• CPC Class Codes: H01L 23/16 Fillings or auxiliary members in containers or encapsulations, e.g. centering rings H01L23/42, H01L23/552 take precedence
• CPC Class Codes: H01L 23/315 the encapsulation having a cavity
• 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 2924/10253 : Silicon [Si]
• CPC Class Codes: H01L 2924/15747 : Copper [Cu] as principal constituent
• CPC Class Codes: H01L 2924/16235 : Connecting to a semiconductor or solid-state bodies, i.e. cap-to-chip
• CPC Class Codes: H01L 2924/181 : Encapsulation
• CPC Class Codes: H01L 2924/3011 : Impedance

Abstract

An accelerometer chip (202) has a molded thermoplastic cap (210) applied on one surface to provide a cavity into which the cantilevered mass (204) of the accelerometer may move. An array of caps is applied to a wafer of accelerometer chips (202) before singulation of the wafer.

Claims

1. A micro machined accelerometer package including:

a chip having a top surface and a bottom surface and having a micro machined accelerometer formed in the chip, the accelerometer including a mass cantilevered from the remainder of the chip to be movable out of the plane of the chip;

a first hollow molded cap bonded to the top surface over at least part of the accelerometer to define a first cavity into which the cantilevered mass may move,

wherein the first molded cap has been bonded to the chip at the wafer stage prior to separation of the wafer into individual chips.

2. An accelerometer package of claim 1 wherein an array of molded caps are simultaneously bonded to the wafer

3. An accelerometer package of claim 2 wherein the array of molded caps are held in alignment by a silicon tool.

4. The package of claim 1 further including a second cap bonded to the second surface of the chip.