MEMS microphone
AssigneeEpcos AG
InventorsGregor Feiertag, Anton Leidl, Wolfgang Pahl, Matthias Winter, Christian Siegel
Life of this patent
Estimating the term…
Abstract
A microphone package wherein an MEMS microphone chip (MIC) is mounted on a substrate (SUB) and is sealed with a cover (ABD) with respect to the substrate. The membrane (MMB) of the microphone chip is connected to a sound entry opening (SEO) in the substrate via an acoustic channel. As a result of defined dimensioning of, in particular, the cross section and length of sound entry opening and channel, an acoustic low-pass filter is formed, the −3 dB attenuation point of which is significantly below the natural resonance of microphone membrane and package.
Claims20
A microphone package, comprising
- a substrate;
- an MEMS microphone chip having a membrane, said microphone chip being mounted on top of the substrate;
- a cover, which is seated on top of the substrate and encloses the microphone chip between itself and the substrate;
- at least one sound entry opening through the substrate or the cover;
- and
- a front volume in front of the membrane, said front volume being connected to the sound entry opening via a channel,
- wherein the at least one sound entry opening, the channel and the front volume form a cavity system and have a geometry defined such that an air friction arises and the cavity system forms an acoustic low-pass filter having a −3 dB attenuation point below the natural resonances of the membrane and the package, and
- wherein the −3 db attenuation point of the acoustic low-pass filter is at a frequency of 75% or less of the natural resonance of the membrane.
A microphone package, comprising
- a substrate;
- an MEMS microphone chip having a membrane, said microphone chip being mounted on top of the substrate;
- a cover, which is seated on top of the substrate and encloses the microphone chip between itself and the substrate;
- at least one sound entry opening through the substrate or the cover;
- and
- a front volume in front of the membrane, said front volume being connected to the sound entry opening via a channel,
- wherein the at least one sound entry opening, the channel and the front volume form a cavity system and have a geometry defined such that an air friction arises and the cavity system forms an acoustic low-pass filter having a −3 dB attenuation point below the natural resonances of the membrane and the package, and
- wherein the aspect ratio of the sound entry opening is between 0.5 and 3.0.
A microphone package, comprising
- a substrate;
- an MEMS microphone chip having a membrane, said microphone chip being mounted on top of the substrate;
- a cover, which is seated on top of the substrate and encloses the microphone chip between itself and the substrate;
- at least one sound entry opening through the substrate or the cover;
- and
- a front volume in front of the membrane, said front volume being connected to the sound entry opening via a channel,
- wherein the at least one sound entry opening, the channel and the front volume form a cavity system and have a geometry defined such that an air friction arises and the cavity system forms an acoustic low-pass filter having a −3 dB attenuation point below the natural resonances of the membrane and the package,
- wherein the membrane of the MEMS microphone chip faces downward to the at least one sound entry opening,
- wherein the distance between the membrane of the MEMS microphone chip and the substrate is 5-100 μm, and
- wherein the cover includes a laminated covering film bearing against the MEMS microphone chip laterally and at the top thereof.
Dependencies are inferred from the claim text.