Patent Application
20080083957
The present invention will be described through detailed illustration of two embodiments referring to the drawings.
Referring to
The substrate 20 is made with an upper surface 21 and a lower surface 22. All of the group 30, the isolative stuff 40 and the conductive shield 50 are mounted on the upper surface 21 of the substrate 20. Solder pads 23 are formed on the lower surface 22 of the substrate 20 for mounting on a printed circuit board or any other carrier. Via the solder pads 23, the substrate 20 is electrically connected to a circuit board of an electronic device that incorporates the MEMS package 10. The substrate 20 defines a sound aperture 24 via which sound travels.
The group 30 includes a plurality of components for executing the functions of the MEMS package 10. Preferably, the group 30 includes a MEMS microphone 31, an application specific integrated circuit 32 (“ASIC 32”) and a passive element 34. The MEMS microphone 31 is mounted on the upper face 21 of the substrate 20. The MEMS microphone 30 includes a diaphragm 311, a chamber 312, and a perforated back plate 313. The chamber 312 is in communication with the sound aperture 24, and the diaphragm 311 is aligned with the sound aperture 24. The diaphragm 311 and the perforated back plate 313 form an electrical capacitor. Sound reaches and causes the diaphragm 311 to deflect in response to the pressure thereof. Thus, the capacitance of the MEMS microphone 30 varies.
A cover 33 is mounted on the MEMS microphone 31 so that a chamber 331 is defined by the cover 33 and the diaphragm 311. The chamber 331 allows the vibration produced by the diaphragm 311.
The ASIC 32 is mounted on the upper surface 21 of the substrate 20. The ASIC 32 is electrically connected to the substrate 20 by at least one wire 321. On the other hand, the ASIC 32 is electrically connected to the MEMS microphone 31 by at least one wire 322.
The passive element 34 is mounted on the upper face 21 of the substrate 20. The passive element 34 may be a capacitor, resistor or inductance.
In use, on receiving the sound, the MEMS microphone 31 generates the changes in the capacitance thereof. On receiving the changes in the capacitance, the ASIC 32 produces electric signals corresponding to the changes in the capacitance. The electric signals are passed through the passive element 34 while the fundamental characteristics thereof are not changed.
isolative stuff 40 is provided on the group 30 and the upper surface 21 of the substrate 20, thus completely sealing the group 30. In specific, all of the MEMS microphone 31, the ASIC 32 and the passive element 34 are sealed by the isolative stuff 40. Therefore, the group 30 is protected from moisture that would otherwise damage the group 30.
The isolative stuff 40 is made of a molding compound generally used during the packaging of integrated circuits. The dimensions, such as the thickness and area, of the isolative stuff 40 are determined according to the desired dimensions of the MEMS package 10.
The conductive shield 50 is mounted on the isolative stuff 40. The conductive shield 50 includes a rim 51 mounted on the upper face 21 of the substrate 20. The rim 51 is directly electrically connected to the electronic device. Hence, the conductive shield 50 protects the group 30 mounted on the upper surface 21 of the substrate 20 from electromagnetic interference. Preferably, the conductive shield 50 is provided by vacuum sputtering.
Referring to
Referring to
The MEMS package according to the present invention exhibits several advantages. Firstly, by the isolative stuff, the components are sealed and protected from moisture that would otherwise be entailed by change in temperature.
Secondly, it can be made as small as possible since the dimensions of the isolative stuff are controlled according to various needs.
Thirdly, the components are protected from electromagnetic interference by the conductive shield provided on the isolative stuff and connected to the electronic device that incorporates the MEMS package.
The present invention has been described via the detailed illustration of the embodiments. Those skilled in the art can derive variations from the embodiments without departing from the scope of the present invention. Therefore, the embodiments shall not limit the scope of the present invention defined in the claims.
