MEMS Microphone Package Conductive Adhesion Layer
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Solution Overview
Problem
The existing MEMS microphone packaging process using tin solder paste often results in solder splashing, which contaminates the ASIC and MEMS microphone, leading to reduced performance due to the splashed material.
Innovation Solution
The use of a conductive adhesion layer, such as conductive epoxy, is introduced to replace the solder paste layer, and an underfill layer is applied to cover the conductive adhesion layer and fill any seams, preventing solder splashing and ensuring effective adhesion of the cap structure without contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If tin solder paste is used to ground the metal cap, then the metal cap can be properly grounded and adhered to the packaging substrate, but the tin solder paste splashes at high temperature and contaminates the ASIC and MEMS microphone
Solution Approach 1:
A conductive adhesion layer is introduced as an intermediary between the metal cap and the packaging substrate. This conductive adhesion layer serves dual functions: it provides grounding connectivity (replacing the solder paste's electrical function) and acts as a barrier to prevent contamination of the ASIC and MEMS microphone. The conductive adhesion layer is disposed on the packaging substrate surrounding the integrated circuit and MEMS microphone, with the metal cap's bottom part adhered to it.
Solution Approach 2:
The grounding and adhesion function is segmented into two separate components: the conductive adhesion layer (providing electrical connectivity and contamination barrier) and the metal cap (providing mechanical protection and grounding). This segmentation allows each component to optimize its specific function without the compromises required when using a single material like solder paste for both purposes.
2Object-affected harmful factors
If conductive adhesion layer is used to replace solder paste, then contamination is prevented, but additional layers and processes are required
Solution Approach 1:
The conductive adhesion layer is designed to perform multiple functions simultaneously: it provides electrical conductivity for grounding, mechanical adhesion to bond the metal cap to the substrate, and contamination barrier protection. By making this single layer multi-functional, the overall package structure complexity is minimized despite the addition of the conductive adhesion layer.
Solution Approach 2:
The grounding function and adhesion function are merged into a single conductive adhesion layer, eliminating the need for separate solder paste application and reducing the number of discrete components. This merging simplifies the overall structure compared to using multiple separate layers for each function.
3Reliability
If underfill layer is added to cover conductive adhesion layer, then seams are filled and protection is enhanced, but manufacturing complexity increases
Solution Approach 1:
The underfill layer is applied in advance to cover the conductive adhesion layer and fill any seams or gaps before the metal cap is fully assembled. This preliminary action ensures that potential contamination pathways are sealed beforehand, improving package integrity without requiring complex post-assembly modifications.
Solution Approach 2:
The underfill layer serves as a protective cushioning layer that fills gaps and seams in advance, preventing potential contamination and providing mechanical support. This beforehand protection measures prevents future reliability issues without adding complex manufacturing steps.
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 solution effectively eliminates the solder splashing effect, ensuring the integrity and performance of the MEMS microphone package by preventing contamination and enhancing the reliability of the packaging process.
Implementation Method 1
A conductive adhesion layer is disposed on the packaging substrate, surrounding the integrated circuit and the MEMS microphone. A cap structure has a bottom part being adhered to the conductive adhesion layer.
Implementation Method 2
An underfill layer is disposed on the packaging substrate, covering an outer side of the conductive adhesion layer.
Data Source
AI summary
A structure of micro-electro-mechanical-system (MEMS) microphone package includes a packaging substrate and an integrated circuit disposed on the packaging substrate. In addition, a MEMS microphone is disposed on the packaging substrate, wherein the MEMS microphone is electrically connected to the integrated circuit. A conductive adhesion layer is disposed on the packaging substrate, surrounding the integrated circuit and the MEMS microphone. A cap structure has a bottom part being adhered to the conductive adhesion layer. An underfill layer is disposed on the packaging substrate, covering an outer side of the conductive adhesion layer.