Packaged MEMS Microphone Via Interconnect Parasitic Reduction
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Solution Overview
Problem
MEMS microphones packaged with wire bonds increase the overall footprint and are susceptible to electromagnetic interference due to parasitic capacitance from interconnects.
Innovation Solution
A packaged microphone design with a base and lid forming an interior chamber, where the MEMS microphone and integrated circuit chip are secured with a via for electrical connection, and a wire bond connects the microphone to the chip, minimizing surface circuit traces and forming a partial electromagnetic shield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wire bonds are used to electrically connect the MEMS microphone to the base, then electrical connection is achieved, but the footprint of the packaged microphone increases
Solution Approach 1:
The patent combines the electrical connection function with the mechanical support structure by integrating the wire bond connection into the existing package architecture. The wire bond is routed through the package interior rather than along the exterior surface, merging the electrical interconnect function with the package housing structure, thereby achieving electrical connection without increasing the external footprint.
Solution Approach 2:
The patent transitions the wire bond routing from a two-dimensional surface path to a three-dimensional path through the package interior. By routing the wire bond vertically through the package depth rather than horizontally across the surface, the design utilizes the Z-dimension to achieve electrical connection without expanding the X-Y footprint.
2Reliability
If wire bonds and interconnects are used for electrical connection, then electrical connectivity is achieved, but parasitic capacitance increases causing electromagnetic interference
Solution Approach 1:
The patent extracts the wire bond from the traditional surface-mounted configuration and relocates it into the package interior, separating it from the external electromagnetic environment. This extraction removes the wire bond from the harmful electromagnetic field region, reducing parasitic capacitance and electromagnetic interference while maintaining electrical connectivity.
Solution Approach 2:
The package interior structure serves as an intermediary medium that shields the wire bond from external electromagnetic interference. By placing the wire bond within the enclosed package space, the package housing acts as a mediator that isolates the sensitive electrical interconnect from harmful external electromagnetic fields, reducing parasitic effects.
Data Source
AI summary
A packaged microphone has a base with a top face, a lid coupled to the base and forming an interior, and a MEMS microphone (i.e., a die or chip) secured to the top face of the base within the interior. The packaged microphone also includes a circuit chip secured to the top face of the base within the interior. The circuit chip has a top surface with a top pad, a bottom surface with a bottom pad, and a via. The bottom pad is electrically connected to the base, and the via electrically connects the top pad with the bottom pad. A wire bond is connected between the MEMS microphone and the top pad on the circuit chip. The MEMS microphone is electrically connected to the bottom pad and the base through the via.