MEMS Microphone Packaging Using Conductive Frame and Insulator
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Solution Overview
Problem
Current MEMS microphone packaging is expensive and large, failing to meet the demand for smaller, cost-effective solutions for portable devices, while also requiring protection of the delicate diaphragm from environmental contaminants and stresses.
Innovation Solution
The proposed solution involves a conductive frame with a silicon die and insulator, forming a sealed cavity for the diaphragm to vibrate, with electrical contact established through terminals, using materials like copper leadframes and NiPdAu plating for electromagnetic interference shielding, and a molded cavity design that is simple to manufacture and robust, integrating the silicon die with other components like ASICs for standalone chip functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional MEMS microphone packaging is used, then the diaphragm is protected from environmental contaminants, but the packaging size and cost increase
Solution Approach 1:
The patent implements nesting by placing the silicon die containing the diaphragm inside a cavity formed in the insulator material. The conductive frame is then positioned within this cavity, creating a nested structure where each component is housed within the previous one. This nested arrangement provides protective enclosure while minimizing the overall packaging volume, as the components utilize the internal space of the insulator cavity rather than requiring separate protective housings.
Solution Approach 2:
The patent merges multiple functions into the insulator component: it provides structural support, electrical insulation, acoustic sealing, and mechanical protection for the diaphragm. The conductive frame simultaneously provides EMI shielding and structural support. This functional merging eliminates the need for separate protective components, reducing overall packaging size while maintaining comprehensive protection of the diaphragm.
2Reliability
If conventional MEMS microphone packaging is used, then the diaphragm is protected from environmental contaminants, but the manufacturing cost increases
Solution Approach 1:
The patent combines multiple protective and functional features into integrated components: the insulator provides both structural support and acoustic sealing, the conductive frame provides both EMI shielding and mechanical support, and the cavity formation process simultaneously creates the protective enclosure and mounting structure. This integration reduces the number of separate components and assembly steps, thereby lowering manufacturing complexity and cost while maintaining comprehensive diaphragm protection.
Solution Approach 2:
The patent utilizes standard insulator materials and common manufacturing processes (cavity formation, adhesive bonding, conductive frame attachment) that are well-established in the industry. By employing conventional materials and techniques rather than specialized processes, the design achieves cost-effective manufacturing while still providing reliable protection for the diaphragm through proper structural design and material selection.
3Productivity
If a sealed cavity is formed for diaphragm vibration, then sound transmission efficiency improves, but the packaging complexity increases
Solution Approach 1:
The patent merges the cavity formation with the insulator structure itself, rather than requiring a separate cavity component. The insulator is designed with an integrated cavity that naturally forms the sealed acoustic environment. This approach achieves efficient sound transmission to the diaphragm while avoiding the complexity of additional cavity-sealing components or multi-step assembly processes.
Solution Approach 2:
The patent uses a thin adhesive layer to seal the cavity around the silicon die, creating an effective acoustic seal without requiring thick or complex sealing structures. This thin-film sealing approach maintains the compactness of the design and simplifies the overall packaging structure while still providing the necessary sealed cavity for efficient sound transmission to the diaphragm.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach results in a reliable, cost-effective, and compact packaging solution that protects the diaphragm and provides efficient sound transmission, suitable for use in personal electronics, with improved reliability and reduced size, addressing the need for smaller form factors in portable devices.
Implementation Method 1
using materials like copper leadframes and NiPdAu plating for electromagnetic interference shielding
Implementation Method 2
the silicon die including a vibratory diaphragm
Data Source
AI summary
This document discusses, among other things, a conductive frame, a silicon die coupled to the conductive frame, the silicon die including a vibratory diaphragm, the die having a silicon die top opposite a silicon die bottom, with a silicon die port extending through the silicon die to the vibratory diaphragm, with a silicon die terminal in electrical communication with the conductive frame and an insulator affixed to the conductive frame and the silicon die, with the insulator extending through interstices in the conductive frame to a conductive frame bottom of the conductive frame, and around an exterior of the silicon die to the silicon die top, with the insulator physically affixed to the silicon die and to the conductive frame, with the silicon die port exposed and with a conductive frame terminal disposed at the conductive frame bottom in electrical communication with the silicon die terminal.