Rigid Interposer Simplifies Transducer Array Interconnections
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Solution Overview
Problem
The high complexity of interconnections between ultrasound transducer cells, ASICs, and flexible circuits in ultrasound transducer arrays leads to increased costs due to the need for a large number of individual connections.
Innovation Solution
The use of a rigid interposer to facilitate a first level of interconnection between ASICs and transducer cells, simplifying the outputs and reducing the complexity of the second level of interconnection with the flexible circuit, thereby reducing the number of layers and manufacturing costs of the flexible circuit and overall EAM.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If direct interconnection between ASIC and flexible circuit is implemented, then electrical connection is achieved, but the complexity of interconnection increases and cost rises
Solution Approach 1:
A rigid interposer is introduced as an intermediary component between the ASIC and the flexible circuit. The interposer provides a standardized interface with a grid of contact pads that simplifies the interconnection architecture. Instead of directly connecting ASIC outputs to flexible circuit traces, the interposer mediates the connection, reducing the number of individual connection points required and simplifying the overall manufacturing process.
Solution Approach 2:
The interconnection system is segmented into distinct functional layers: the ASIC layer, the rigid interposer layer, and the flexible circuit layer. This segmentation allows each component to be optimized independently - the ASIC can be designed with standard output configurations, the interposer provides a fixed grid interface, and the flexible circuit can use simpler trace patterns. This modular approach reduces overall system complexity and manufacturing difficulty.
2Reliability
If multiple layers in flexible circuit are used to achieve necessary connections, then electrical interconnection is maintained, but manufacturing cost increases
Solution Approach 1:
The rigid interposer serves as a mediator that consolidates multiple connection points into a standardized grid interface. This allows the flexible circuit to use fewer layers with simpler trace routing, as the interposer provides the necessary signal distribution function that would otherwise require multiple complex flexible circuit layers. The connection reliability is maintained through the robust rigid interface while manufacturing costs are reduced.
Solution Approach 2:
The connection architecture transitions from a planar two-dimensional trace routing problem in the flexible circuit to a three-dimensional stacked architecture. The rigid interposer provides vertical stacking of functional layers, allowing connections to be made through Z-axis vias and stacked interfaces rather than requiring extensive lateral trace routing. This dimensional change simplifies the flexible circuit design and reduces the number of layers needed.
Data Source
AI summary
An architecture of an Electro-Acoustic Module (EAM) of an ultrasound probe is provided. In one example, the EAM includes a rigid interposer positioned between an Application Specific Integrated Circuit (ASIC) chip of the EAM and a flex interconnect coupled to a connector of the EAM, where the interposer facilitates an electrical interconnection between a plurality of transducer cells of the EAM, the ASIC, and the flex interconnect. The interposer may be electrically coupled to the flex interconnect at either a top side or a bottom side of the interposer, via Anisotropic Conductive Film (ACF) and/or Anisotropic Conductive Paste (ACP) or via wire bonds.