Imaging Catheter Backing Structure for CTE-Matched Thermal Stability

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Solution Overview

Problem

The warping and bending of intraluminal imaging components due to differing coefficients of thermal expansion (CTE) between the ASIC and backing layer materials under thermal excursions, which can lead to damage and poor reliability, are not adequately addressed in existing designs.

Innovation Solution

Intraluminal imaging components are designed with a backing material having a CTE closer to that of the semiconductor IC layer, and optionally an additional support layer with the same material, to balance thermal stress and maintain acoustic attenuation performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a polymeric backing layer is used with silicon ASIC, then acoustic attenuation is achieved, but thermal expansion mismatch causes warping and bending under thermal excursions

Engineering Contradiction:

Improvestructural stabilityVSAvoidthermal stress

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

An intermediate layer with intermediate CTE is introduced between the silicon ASIC and polymeric backing layer. This mediator layer has a CTE value between that of silicon and the polymer, gradually transitioning the thermal expansion properties and reducing the stress concentration at the interface, thereby preventing warping and bending under thermal excursions

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

A composite backing structure is created by combining multiple materials with different CTE properties in a layered configuration. The composite structure includes silicon ASIC, intermediate layer, and polymeric backing layer, where each layer contributes its specific properties to achieve both acoustic attenuation and thermal stress management

Inventive Principle:

Principle #40Composite materials

2Volume of moving object

If backing layer thickness is reduced for miniaturization, then device size is reduced, but thermal stress concentration increases causing warping

Engineering Contradiction:

Improvedevice sizeVSAvoidstructural stability

Core Design Contradiction:

Volume of moving objectVSStability of the object's composition

Solution Approach 1:

The backing structure is segmented into multiple thin layers instead of a single thick layer. This segmentation allows each layer to be optimized for specific functions (acoustic attenuation, thermal stress management) while maintaining overall compactness and preventing warping through the intermediate CTE layer

Inventive Principle:

Principle #1Segmentation

3Reliability

If standard polymeric backing material is used, then acoustic attenuation performance is achieved, but CTE mismatch with silicon causes bending under thermal excursions

Engineering Contradiction:

Improveacoustic performanceVSAvoidgeometric stability

Core Design Contradiction:

ReliabilityVSShape

Solution Approach 1:

Different regions of the backing structure are assigned different material properties tailored to local requirements. The intermediate layer is specifically positioned at the silicon-polymer interface where thermal stress concentration occurs, providing localized CTE matching to prevent bending while allowing the polymeric region to maintain its acoustic attenuation properties

Inventive Principle:

Principle #3Local quality

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

The solution reduces thermal stress and eliminates bending, enhancing the stability and reliability of the imaging components by matching CTEs and maintaining acoustic performance.

Implementation Method 1

the degree of expansion during heating and contraction during cooling is represented by a coefficient of thermal expansion (CTE). The silicon material of the ASIC and the polymeric material of the backing layer have highly differentiating CTEs

Methodology Applied

Scientific EffectCoefficient of thermal expansion (CTE): Thermal Expansion

Implementation Method 2

The de-matching layer can reflect forward ultrasound waves travelling toward the backside of the matrix array

Methodology Applied

Scientific EffectAcoustic reflection: Reflection

Implementation Method 3

The backing layer can disperse or dampen remaining backward travelling ultrasound waves

Methodology Applied

Scientific EffectAcoustic attenuation: Acoustic Absorption

Data Source

PatentUS12558067B2Temperature insensitive backing structure for intraluminal imaging devices

Publication Date: 2026.02.24 KONINKLIJKE PHILIPS NV

AI summary

An imaging catheter assembly is provided. In one embodiment, the imaging catheter assembly includes a flexible elongate member including a distal portion and a proximal portion; and an imaging component coupled to the distal portion of the flexible elongate member, wherein the imaging component includes: an integrated circuit (IC) layer that includes a semiconductor material; an array of ultrasound transducer elements coupled to a first side of the IC layer; and a backing layer coupled to a second side of the IC layer opposite the first side, wherein the backing layer includes a backing material, and wherein a coefficient of thermal expansion (CTE) difference between the semiconductor material and the backing material is less than 23 parts per million per degree Centigrade (ppm/C).