Stacked MEMS Device Packaging with Integrated Circuit Chip
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Solution Overview
Problem
The packaging of microelectromechanical systems (MEMS) devices, particularly switches, often increases the overall device size and causes RF interference due to bond wires, which contradicts the industry trend of reducing component size and footprint while maintaining functionality.
Innovation Solution
A MEMS apparatus with a base and a MEMS device secured to it, where the MEMS device has a movable member controlled by a circuit chip, and is either flip-chip connected or uses conductive bumps and vias for electrical connections, with a cap providing electrical communication and reducing RF interference by using high-conductivity materials like gold for the movable member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional packaging methods are used for MEMS switches, then the device can be assembled and function, but the overall device size and footprint increase
Solution Approach 1:
The patent combines the MEMS switch device with the packaging structure into a single integrated unit. The device housing serves dual purposes as both the packaging container and the RF shield, eliminating the need for separate packaging components and reducing overall device size while maintaining functionality.
Solution Approach 2:
The housing structure performs multiple functions simultaneously: it provides mechanical packaging for the MEMS switch, acts as an RF shield to contain electromagnetic interference, and serves as the outer casing for the entire device. This multi-functionality reduces the number of separate components needed.
2Reliability
If bond wires are used to conduct RF signals in MEMS switches, then electrical connection is achieved, but RF interference and RF losses increase
Solution Approach 1:
The patent removes bond wires from the RF signal path entirely, extracting the source of RF interference and loss. Instead of using traditional bond wire connections, the design employs direct metallurgical connections or conductive structures integrated into the MEMS device architecture, eliminating the harmful RF effects associated with bond wires.
Solution Approach 2:
The patent replaces the mechanical bond wire connection system with an integrated conductive structure that is part of the MEMS device itself. This substitution eliminates the mechanical bond wire interface that causes RF interference, using instead a monolithic or closely integrated conductive path that reduces RF losses and interference.
3Area of stationary object
If the MEMS device is made compact to reduce footprint, then device size decreases, but packaging becomes more challenging
Solution Approach 1:
The patent employs a nested arrangement where the MEMS switch device is placed inside the housing structure, and the RF shield is integrated within the same space. This nesting approach maximizes space utilization, allowing compact dimensions while maintaining all necessary functional components and simplifying assembly through a nested construction methodology.
Data Source
AI summary
A MEMS apparatus has a MEMS device sandwiched between a base and a circuit chip. The movable member of the MEMS device is attached at the side up against the circuit chip. The movable member may be mounted on a substrate of the MEMS device or formed directly on a passivation layer on the circuit chip. The circuit chip provides control signals to the MEMS device through wire bonds, vias through the MEMS device or a conductive path such as solder balls external to the MEMS device.