Patent Application
20150304751
1. Field of the Invention
The present invention relates to microphone technology, and more particularly to a chip-stacked microphone that comprises an application-specific integrated circuit chip (ASIC) and an acoustic wave transducer module stacked on the application-specific integrated circuit chip (ASIC), having the characteristics of small size and sufficient back chamber space.
2. Description of the Related Art
A conventional microphone 70, as shown in
To solve the aforesaid problem, some commercial microphones have the acoustic wave transducer module be stacked on the application-specific integrated circuit chip (ASIC) and make a through hole at the center of application-specific integrated circuit chip (ASIC) and a sound hole at the substrate in alignment with the through hole for the passing of acoustic waves to the diaphragm. A microphone of this design reduces the area demand for footprint, however, the application-specific integrated circuit chip (ASIC) needs to render a space area for making the through hole. Thus, this design has limited effects on reducing the area of the substrate and the overall dimension of the microphone. Further, sacrificing the internal space of the cover not for back chamber will adversely affect the performance of the microphone.
The present invention has been accomplished under the circumstances in view. It is the main object of the present invention to provide a chip-stacked microphone, which effectively reduces the area of the substrate and maintains or increases the internal space of the cover for back chamber, achieving the technical effects of small size and high performance.
To achieve this and other objects of the present invention, the invention provides a chip-stacked microphone comprising a substrate, an application-specific integrated circuit chip (ASIC), an acoustic wave transducer module and a cover, wherein the application-specific integrated circuit chip (ASIC) is mounted on the substrate and electrically connected with the substrate. The acoustic wave transducer module is mounted on the application-specific integrated circuit chip (ASIC), and electrically connected to the application-specific integrated circuit chip (ASIC) using Ball Grid Array (BGA) packaging technology, enabling an acoustic wave to pass through the gap between the acoustic wave transducer module and the application-specific integrated circuit chip (ASIC). The cover is covered over the acoustic wave transducer module and connected to the substrate, defining therein a sound hole.
Thus, the chip-stacked microphone of the present invention has the acoustic wave transducer module be stacked on application-specific integrated circuit chip (ASIC) without making any hole on the application-specific integrated circuit chip (ASIC), effectively reducing the area requirement for footprint to minimize the area of the substrate, and fully utilizing the space between the two modules and the cover for back chamber to maintain the overall performance of the microphone.
Preferably, the application-specific integrated circuit chip (ASIC) is electrically connected to the substrate by wire bonding technology or flip chip bonding technology.
Preferably, the application-specific integrated circuit chip (ASIC) has a plurality of Through Silicon Vias formed therein for the application of Redistribution Layer (RDL) technology.
Further, the acoustic wave transducer module comprises a diaphragm, and the sound hole is disposed above the diaphragm. Preferably, the chip-stacked microphone further comprises a mask connected to the cover and covered over the sound hole.
Other advantages and features of the present invention will be fully understood by reference to the following specification in conjunction with the accompanying drawings, in which like reference signs denote like components of structure.
Referring to
The substrate 10 comprises a plurality of conducting regions 11 at a top wall thereof, at least one solder pad 12 at each conducting region 11, and a plurality of solder pads 13 at an opposing bottom wall thereof for electric connection with external components.
The application-specific integrated circuit chip (ASIC) 20 is mounted at and electrically connected with the substrate 10, comprising a circuit layer 21 located at a top wall thereof, a plurality of solder pads 22 mounted at the circuit layer 21, a plurality of metal bumps 24 located at an opposing bottom wall thereof, and a plurality of Through Silicon Vias (TSVs) 23 extending through the opposing top and bottom walls with respective opposing top and bottom ends thereof respectively electrically connected to the solder pads 22 and the metal bumps 24. Thus, the application-specific integrated circuit chip (ASIC) 20 can be electrically connected to the solder pads 12 at the substrate 10 using flip chip bonding technology for allowing input of drive voltage of the microphone 1 and input/output of signals of the microphone 1.
The acoustic wave transducer module 30 is mounted at a top side relative to the application-specific integrated circuit chip (ASIC) 20, comprising a diaphragm 31 and a plurality of solder pads 32 disposed adjacent to one side of the diaphragm 31. The solder pads 32 of the acoustic wave transducer module 30 are respectively electrically connected to the respective solder pads 22 at the circuit layer 21 of the application-specific integrated circuit chip (ASIC) 20 with solder balls L using Ball Grid Array (BGA) packaging technology, thereby electrically connecting the acoustic wave transducer module 30 to the application-specific integrated circuit chip (ASIC) 20.
The cover 40 is covered over the acoustic wave transducer module 30, and connected to the substrate 10 beyond the conducting regions 11. The cover 40 can be made of metal to protect the microphone 1 against impact, external dust and magnetic waves. Further, the cover 40 has a sound hole 41 disposed above the diaphragm 31 of the acoustic wave transducer module 30, allowing acoustic wave S to be directly transmitted through the sound hole 41 to the diaphragm 31. Further, the inner wall of the cover 40 defines with the outer wall of the acoustic wave transducer module 30 and the outer wall of the application-specific integrated circuit chip (ASIC) 20 a back chamber 42.
In application, when the chip-stacked microphone 1 receives an acoustic wave, the acoustic wave S goes through the sound hole 41 and the acoustic wave transducer module 30 to vibrate the diaphragm 31. Further, the arrangement of the solder balls L between the acoustic wave transducer module 30 and the application-specific integrated circuit chip (ASIC) 20 causes formation of a passage between the application-specific integrated circuit chip (ASIC) 20 and the acoustic wave transducer module 30 for the passing of the acoustic wave S to the back chamber 42, enabling the acoustic wave S to induce acoustic wave resonances in the back chamber 42 and to further improve the performance of the chip-stacked microphone 1 for intaking sound from the back. In spatial utilization, the acoustic wave transducer module 30 is stacked on the application-specific integrated circuit chip (ASIC) 20, and the application-specific integrated circuit chip (ASIC) 20 is electrically connected to the substrate 10 through the Through Silicon Vias 23, minimizing the requirement for footprint for the application-specific integrated circuit chip (ASIC) 20.
It is to be noted that the application of Ball Grid Array (BGA) packaging technology in the present invention enables the acoustic wave transducer module 30 to be electrically connected to the application-specific integrated circuit chip (ASIC) 20, however, the invention is not limited to the application of Ball Grid Array (BGA) packaging technology, any person skilled in the art can employ Plastic Ball Grid Array (PBGA) technology and Flip Chip Ball Grid Array (FCBGA) technology, or any other substitute three-dimensional (3D) Packaging technology, such as Package on Package (PoP) or Stacked Die Package technology to electrically connect the acoustic wave transducer module 30 to the application-specific integrated circuit chip (ASIC) 20, allowing an acoustic wave to pass through the back chamber.
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Although particular embodiments of the invention have been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims.
