MEMS microphone

The invention discloses a MEMS microphone, which includes a case with an accommodating cavity and an acoustic vent arranged on the case, a housing with an empty cavity as well as MEMS and ASIC chips with a back cavity are arranged inside the accommodating cavity. The housing is installed on the case, the MEMS chips are installed in the housing, the housing is arranged with a through hole connecting the empty cavity and the back cavity. The housing is also arranged with a vent hole. The MEMS microphone also includes a membrane flap arranged on the housing and used to close the vent hole. The membrane flap changes its shape under airflow effects and opens the vent hole. The MEMS microphone of this invention can avoid the diaphragm of the MEMS chips being damaged by airflow impact.

FIELD OF THE PRESENT DISCLOSURE

The present disclosure relates to the field of microphones, especially to a MEMS microphone.

DESCRIPTION OF RELATED ART

The MEMS microphone of the related technology comprises a case with an accommodating cavity, an acoustic hole arranged on the case and MEMS chips and ASIC chips accommodated in the accommodating cavity.

The diaphragm of the MEMS chip is often damaged by airflow impact caused by gas blowing, drop or temperature change, the usual solution is to open a groove or a hole in the diaphragm which penetrates the diaphragm to balance the gas pressure on both sides of the diaphragm. However, opening a groove or a hole in the diaphragm will reduce the strength of the diaphragm itself.

Therefore it is necessary to provide an improved MEMS microphone for overcoming the above-mentioned disadvantages.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

As shown byFIGS. 1 to 4, the present disclosure provides an MEMS microphone100, which includes a case1with an accommodating cavity10, and an acoustic vent2arranged on the case1. In this embodiment, the case1includes a circuit board11and a cover12connected as a cover to the circuit board11, wherein the circuit board11and the cover12form the accommodating cavity10. The cover12is made of metal materials.

A housing3with an empty cavity30, a MEMS chip4with a back cavity40and an ASIC chip5are arranged inside the accommodating cavity10, and the MEMS chips4include a diaphragm41. In this embodiment, the housing3is installed on the circuit board11, of course, optionally, the housing3can also be installed on the cover12. Preferably, the housing3is made of silicon materials.

The MEMS chip4is installed on the housing3, a through hole31connecting to the empty cavity30and the back cavity40is arranged in the housing3, and a vent hole32connecting to the empty cavity30and the accommodating cavity10is also arranged in the housing3. The installation location of the ASIC chips5can be chosen randomly, preferably, the ASIC chip5is installed on the housing3, by choosing this installation mode, the ASIC chip5will not occupy the space and position of the housing3and the housing3has enough space for a bigger empty cavity30. The empty cavity30can greatly reduce the packaging stress, and reduce the impact of packaging and SMT mounting in late stage on product performance.

The MEMS microphone100also includes a membrane flap6arranged on the housing3, in the normal state, the membrane flap6closes the vent hole32, the membrane flap6can deform under the influence of airflow and open the vent hole32. Preferably, the membrane flap6remains in a critical damping state, that is, the membrane flap6can open already under minor influence of airflow, thus achieving fast response. Of course, also can design the size of the vent hole32, the venting effects can also be controlled and adjusted by changing the size and shape of the vent hole32and the damping of the membrane flap6. The membrane flap6can be silicone film or plastic film.

In this embodiment, the outer periphery of the membrane flap6is fixedly connected with the housing3, a gap60is formed in the membrane flap6to divide the membrane flap6into several sub-membrane-flaps. Referring toFIG. 3, the gap60divide the membrane flap6into 4 sub-membrane-flaps, that is, sub-membrane-flap61, sub-membrane-flap62, sub-membrane-flap63and sub-membrane-flap64. Of course, the form of the gap60is not limited to form “+”, it can be in the form of “−”, “Y” and other forms, and the number of the divided sub-membrane-flaps is not limited to 4, either. In addition to the way of forming sub-membrane-flaps, the way the membrane flap6opens the vent hole32can also be different, it can also be in the way that a part of the membrane flap6is fixed and the other part is not fixed, or in other ways that the membrane flap6can open the vent hole32.

In this embodiment, the acoustic vent2is arranged on the circuit board11and is connected to the empty cavity30, an ultrasonic microphone can be achieved with a suitable design of the empty cavity30. Preferably, the acoustic vent2and the through hole31are arranged staggered from each other, which can effectively reduce the risk of particulate matters entering the microphone.

Referring toFIG. 4, which is the gas flow direction diagram of the MEMS microphone100, the arrows in the Fig. are used to represent the gas flow, the membrane flap6deforms due to the influence of gas flow and opens the vent hole32, which can balance the gas pressure on both sides of the diaphragm41of the MEMS chips4, thus it can be avoided that the diaphragm41of the MEMS chips4get damaged due to gas flow impact. At the same time, it is not necessary to open a groove or a hole in the diaphragm41, which ensures the strength of the diaphragm41itself.

Referring toFIG. 5, which shows another MEMS microphone200provided by the present invention, the MEMS microphone200is different from the above mentioned MEMS microphone100in that: the acoustic vent2′ is arranged on the cover12′, and the acoustic vent2′ is connected to the accommodating cavity10′. The empty cavity30′ can expand the volume of the back cavity40′, thus improving the sensitivity and signal-to-noise ratio.