Patent Application
20130320465
1. Field of the Invention
The present invention relates generally to a microphone module of micro-electro-mechanical system (hereinafter referred to as “MEMS”) and more particularly, to a MEMS microphone module that has a reduced overall package size.
2. Description of the Related Art
As shown in
However, the chamber 16 defined between the metal lid 14 and the circuit board 11 must have enough volume to contain the wire 15, such that the metal lid 14 should be required to maintain a certain height. Therefore, it can be seen that the overall package size of the conventional MEMS microphone module 10 is difficult to be reduced.
The present invention has been accomplished in view of the above-noted circumstances. It is therefore the primary objective of the present invention to provide a MEMS microphone module, which has a small package height so as to have a reduced overall package size.
To achieve the above-mentioned objective, the MEMS microphone module provided by the present invention comprises a first circuit board, a MEMS chip received in a first concavity of the first circuit board, a second circuit board covered on the first circuit board and having an acoustic hole corresponding to the MEMS chip, a second signal layer electrically coupled to a first signal layer of the first circuit board and the MEMS chip, and a second ground layer electrically coupled to a first ground layer of the first circuit board, and an application-specific integrated circuit (ASIC) chip mounted to the second circuit board in such a way that the ASIC chip is accommodated in a second concavity of the first circuit board and electrically coupled to the first signal layer of the first circuit board. A ground shielding structure is defined by the first ground layer of the first circuit board and the second ground layer of the second circuit board to apply an EMI shielding to the MEMS chip and the ASIC chip.
By means of this design, the MEMS microphone module of the present invention is assembled by the two circuit boards and provided with the EMI shielding structure by the internal ground layers of the circuit boards, such that the MEMS microphone module of the present invention can have it's a small package height to attaining the purpose of reducing its overall package volume.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
The present invention will become more fully understood from the detailed description given herein below and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:
Referring to
The first circuit board 30 has a first concavity 31 at the top side thereof, a second concavity 32 at the top side thereof spaced from the first concavity 31. Further, a first signal layer 33 and a first ground layer 34 embedded in the first circuit board 30.
The MEMS chip 40 is received in the first concavity 31 of the first circuit board 30 and attached on the bottom of the first concavity 31.
The second circuit board 60 is covered on the top side of the first circuit board 30, and has a bottom side thereof for attachment of the ASIC chip 50 accommodated in the second concavity 32 of the first circuit board 30. The second circuit board 60 includes an acoustic hole 61 corresponding to the MEMS chip 40, and a second signal layer 62 electrically coupled to the first signal layer 33 of the first circuit board 30 and the MEMS chip 40 through a conductive adhesive 70 and meanwhile electrically coupled to the ASIC chip 50 through a wire 66. Further, a second ground layer 63 of the second circuit board 60 is electrically coupled to the first ground layer 34 of the first circuit board 30 through a conductive adhesive 70, such that a ground shielding structure 80 is defined by the first and second ground layers 34 and 63 to apply an EMI shielding to the MEMS chip 40 and the ASIC chip 50.
When the MEMS microphone module 20 of the present invention is used, the MEMS chip 40 receives the external sounds through the acoustic hole 61 of the second circuit board 60 and converts the sound waves into capacity variations, and then the ASIC chip 50 converts the capacity variations into an electrical signal through the second signal layer 62 of the second circuit board 60, and then the ASIC chip 50 transmits the electrical signal to a signal processor or an amplifier through the first and second signal layers 33 and 62.
As indicated above, the MEMS microphone module 20 of the present invention is assembled by means of the attachment of the two circuit boards 20 and 60, and creates the EMI shielding through the internal ground layers 34 and 63 of the circuit boards 20 and 60, such that the MEMS microphone module 20 of the present invention can have a small package height to attaining the purpose of reducing its overall package volume.
The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.
