MEMS Package Grounding Circuit Layer Charge Dissipation
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Solution Overview
Problem
MEMS package structures face reliability issues due to electric charge accumulation on the lid when in operation, affecting signal quality and system reliability.
Innovation Solution
A package structure with a substrate, lid, wire segments, encapsulant, and circuit layer, where the lid and substrate are electrically connected to a ground conductive element through a circuit layer, preventing charge accumulation by grounding both components, and reducing the number of I/O connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the lid is disposed on the chip to cover the MEMS element, then the MEMS element is protected, but electric charges accumulate on the lid affecting signal quality and reliability
Solution Approach 1:
An encapsulant layer is introduced as an intermediary between the lid and the chip substrate. This encapsulant electrically isolates the lid from the substrate, preventing charge accumulation on the lid while maintaining the protective covering function. The encapsulant acts as a mediator that resolves the electrical interference problem without compromising the structural protection.
Solution Approach 2:
The package structure is segmented into distinct electrical zones: the chip substrate, the encapsulant layer, and the lid. By segmenting the structure and introducing the encapsulant as a separate layer, electrical connectivity is controlled - the lid is physically connected to the substrate for mechanical support but electrically isolated through the encapsulant, preventing harmful charge accumulation.
2Reliability
If wire segments are added to electrically connect the lid and ground pad through the circuit layer, then charge accumulation is prevented, but the device complexity increases
Solution Approach 1:
The encapsulant layer serves multiple functions: it provides electrical isolation between the lid and substrate, mechanically supports the lid structure, and facilitates the routing of wire segments for electrical connection. By making the encapsulant multi-functional, the patent reduces the need for additional separate components, thereby managing complexity while achieving reliable charge dissipation.
Solution Approach 2:
The electrical connection path is merged into the existing structural layers. The wire segments are integrated within the encapsulant layer, and the ground connection is combined with the existing ground pad on the substrate. This merging approach achieves charge dissipation functionality without adding entirely separate connection structures, thus limiting the increase in device complexity.
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 prevents excessive electric charge accumulation on the lid, enhancing the reliability of the MEMS system and reducing the complexity of input/output connections.
Implementation Method 1
at least a first wire segment electrically connected to the ground pad; at least a second wire segment electrically connected to the lid
Implementation Method 2
an encapsulant formed on the substrate for encapsulating the lid and the first and second wire segments
Data Source
AI summary
A package structure is provided, including: a substrate having a ground pad and an MEMS element; a lid disposed on the substrate for covering the MEMS element; a wire segment electrically connected to the ground pad; an encapsulant encapsulating the lid and the wire segment; and a circuit layer formed on the encapsulant and electrically connected to the wire segment and the lid so as to commonly ground the substrate and the lid, thereby releasing accumulated electric charges on the lid so as to improve the reliability of the MEMS system and reduce the number of I/O connections.