cMUT Array Packaging on Dielectric Substrate
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional packaging methods for capacitive micromachined ultrasonic transducer (cMUT) arrays are time-consuming and inefficient, particularly for systems with a large number of elements, as they require individual wire bonding or flip-chip bonding, which occupy significant area and struggle with device insulation.
Innovation Solution
A method for packaging multiple cMUT arrays on a single substrate using a dielectric layer with patterned openings for conductive connections, allowing for batch production and integration of additional components, with a support structure for holding the arrays in place, enabling flexible and dense interconnections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional wire bonding or flip-chip bonding methods are used to connect cMUT arrays to PCB, then electrical connections are established, but the footprint area is large and production time is excessive
Solution Approach 1:
The patent merges the cMUT array fabrication with the PCB substrate fabrication into a single integrated process. The cMUT array is formed directly on the PCB substrate using the same semiconductor manufacturing steps (depositing conductive layers, forming electrodes, creating membranes), eliminating the need for separate wire bonding or flip-chip bonding operations. This integration dramatically reduces the packaging footprint while maintaining reliable electrical connections.
Solution Approach 2:
The patent transitions from conventional three-dimensional packaging (separate cMUT chip bonded to PCB with wires or solder bumps) to a planar two-dimensional integration approach. The cMUT array is fabricated in-situ on the PCB substrate surface, utilizing the substrate plane for both structural support and electrical interconnection, thereby minimizing vertical height and lateral footprint.
2Reliability
If conventional packaging methods are used for cMUT arrays, then individual connections can be made, but production efficiency is low and cost is high
Solution Approach 1:
The patent performs preliminary actions by pre-forming the PCB substrate with integrated circuit patterns, conductive layers, and electrode structures before the cMUT array fabrication. The substrate is prepared in advance with all necessary interconnection pathways, allowing the cMUT elements to be directly connected without subsequent bonding operations. This preliminary preparation enables batch processing and significantly improves production efficiency.
Solution Approach 2:
The cMUT array structure serves multiple functions simultaneously: the PCB substrate acts as both the mechanical support and the electrical interconnection medium, the conductive layers serve as both structural elements and electrical pathways, and the membrane structure provides both acoustic functionality and electrical isolation. This self-service approach eliminates the need for separate connection components and operations.
3Reliability
If standard IC packaging methods are used, then electrical connections are established, but device insulation is difficult to achieve
Solution Approach 1:
The patent applies local quality by implementing electrical insulation only where needed within the integrated structure. Dielectric layers are deposited selectively in specific regions to provide insulation between adjacent cMUT elements and between different conductive layers, rather than requiring complete encapsulation. This localized insulation approach simplifies manufacturing while maintaining electrical isolation where required.
Solution Approach 2:
The patent uses composite material structures combining multiple dielectric layers, conductive layers, and membrane materials in a single integrated fabrication process. The PCB substrate itself serves as a composite structure with embedded conductive traces and insulating layers, which are then built upon with additional functional layers. This composite approach provides built-in insulation throughout the structure without requiring separate insulation fabrication 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 method enables efficient packaging of multiple cMUT arrays with reduced footprint, allowing for higher density interconnections and easier passivation, while lowering production costs by enabling batch processing and integration of auxiliary components.
Implementation Method 1
A method for packaging multiple cMUT arrays on a single substrate using a dielectric layer with patterned openings for conductive connections
Implementation Method 2
a dielectric layer with patterned openings for conductive connections
Data Source
AI summary
Embodiments of a method for packaging cMUT arrays allow packaging multiple cMUT arrays on the same packaging substrate introduced over a side of the cMUT arrays. The packaging substrate is a dielectric layer on which openings are patterned for depositing a conductive layer to connect a cMUT array to VO pads interfacing with external devices. Auxiliary system components may be packaged together with the cMUT arrays. Multiple cMUT arrays and optionally multiple auxiliary system components can be held in place by a larger support structure for batch production. The support structure can be made of an arbitrary size using inexpensive materials.