Silicon Interposer Pitch Redistribution for Ultrasound Arrays
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Solution Overview
Problem
Interconnecting multidimensional transducer arrays with electronics is challenging due to the small size of transducer elements and varying pitches, requiring direct signal connections that are difficult to match with existing ASICs without redesigning them for each new transducer type.
Innovation Solution
A silicon or wafer-based interposer is used to redistribute conductors and match the pitch of acoustic elements with ASIC I/Os, allowing the same ASIC design to be used across different transducer pitches without new development, while also improving thermal management and joint reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If direct signal connections are made from ASICs to acoustic elements, then signal routing is achieved, but the pitch of ASIC I/Os must match the pitch of acoustic elements, requiring redesign of ASICs for each new transducer type
Solution Approach 1:
A silicon interposer is introduced as an intermediary component between the ASIC and the acoustic array. The interposer has conductors on its first surface that connect to the acoustic array and extend to the second surface to connect with the ASIC, serving as a mediator that decouples the pitch matching requirement from the ASIC design itself
Solution Approach 2:
The connection system is segmented into three separate components: the acoustic array, the silicon interposer, and the ASIC. This segmentation allows each component to be designed independently with its own optimal pitch, eliminating the need for ASIC redesign when transducer pitches change
2Productivity
If ASICs are placed as close to acoustic elements as possible, then signal connection efficiency is improved, but thermal management becomes more challenging due to concentrated heat density
Solution Approach 1:
The silicon interposer serves as a thermal intermediary between the ASIC and acoustic array. Silicon's high thermal conductivity allows it to act as a heat spreader, distributing the concentrated heat from the ASIC over a larger area, thereby reducing local heat density while maintaining close proximity for efficient signal connection
3Ease of operation
If micro-beamforming ASICs are used to directly operate acoustic elements, then signal routing capability is achieved, but the pitch of ASIC I/Os must precisely match the pitch of corresponding acoustic elements
Solution Approach 1:
The silicon interposer with its conductor pattern acts as a mediator that handles the pitch transformation. The conductors on the first surface match the acoustic element pitch, while conductors on the second surface match the ASIC I/O pitch, allowing direct operation of acoustic elements without precise pitch matching between ASIC and elements
Solution Approach 2:
The interposer enables parameter change in the pitch domain by transforming the spatial arrangement of conductors between its two surfaces. This allows the system to operate with different pitch parameters at different interfaces without requiring the same pitch throughout the entire connection path
Data Source
AI summary
For transducer connection to an integrated circuit, a silicon or other wafer-based chip is processed to provide signal routing, such as altering the pitch using wafer process deposited conductors. This chip or silicon interposer may be more simply re-designed to relate the pitch of an array to the integrated circuit I/Os, avoiding redesign of the integrated circuit.