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Bottom port surface mount MEMS microphone

  • US 9,051,171 B1
  • Filed: 01/07/2014
  • Issued: 06/09/2015
  • Est. Priority Date: 11/28/2000
  • Status: Expired due to Fees
First Claim
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1. A solder reflow surface mount micro-electro-mechanical system (MEMS) microphone, the microphone comprising:

  • a rectangular substrate comprising;

    a rigid base layer comprised of multiple sub-layers of non-conductive material, each sub-layer having a predetermined coefficient of thermal expansion, wherein the base layer has a planar top surface and a planar bottom surface, the top surface having an interior region and an attachment region, the attachment region disposed between the interior region and the edges of the base layer, and completely bounding the interior region;

    a first plurality of flat metal pads disposed on the top surface of the base layer and defined by a first solder mask layer;

    a second plurality of flat metal pads disposed on the bottom surface of the base layer and defined by a second solder mask layer, the second plurality of metal pads arranged to be within a perimeter of the bottom surface of the base layer;

    one or more electrical pathways disposed completely within the base layer, wherein the pathways electrically couple one or more of the first plurality of metal pads on the top surface of the base layer to one or more of the second plurality of metal pads on the bottom surface of the base layer; and

    an acoustic port disposed in the interior region of the base layer and passing completely through the base layer, wherein the acoustic port is disposed in a position offset from a centerpoint of the substrate, and wherein one of the second plurality of metal pads is a metal ring that completely surrounds the acoustic port in the base layer and has an inner diameter that is greater than a diameter of the acoustic port;

    a MEMS microphone die mounted to the top surface of the substrate and electrically coupled to at least one of the first plurality of metal pads on the top surface of the substrate, the MEMS microphone die being disposed directly over the acoustic port in the base layer; and

    a solid single-piece rectangular cover having a predetermined shape, the rectangular cover comprising a top portion and a substantially vertical and continuous sidewall portion that adjoins the top portion at an angle and that completely surrounds and supports the top portion, the sidewall portion having a predetermined height, an exterior sidewall surface, an interior sidewall surface, and an attachment surface,wherein the attachment surface of the sidewall portion of the cover is aligned with and attached to the attachment region of the top surface of the base layer of the substrate, andwherein the predetermined height of the sidewall portion of the cover, the interior sidewall surface of the sidewall portion of the cover, and the interior surface of the top portion of the cover, in cooperation with the interior region of the top surface of the base layer, define an acoustic chamber for the MEMS microphone die and provide a protective enclosure for the MEMS microphone die to reduce electromagnetic interference.

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