Hybrid Focal-Plane Array Curvature via Internal Slits

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing focal-plane arrays, particularly those used in infrared sensing, face limitations in curvature and alignment, leading to issues such as misalignment, wrinkling, and reduced operational window when attempting to achieve sharper images and higher frame rates at lower light levels.

Innovation Solution

A hybrid focal-plane array with internal slits and defect-free edges, manufactured by forming a read-out integrated circuit and a detector die separately and aligning them with flip-chip bonding, allowing for greater spherical curvature without cracking or misalignment, and reducing thickness through lapping and etching.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Shape

If a flat FPA is mechanically curved to achieve sharper images and higher frame rates, then image quality and operational window are improved, but the FPA creeps back to flat state over time and may crease or wrinkle when excessively curved

Engineering Contradiction:

ImprovecurvatureVSAvoidalignment stability

Core Design Contradiction:

ShapeVSReliability

Solution Approach 1:

The FPA is divided into multiple individual FPAs that are stitched together on a curved die, allowing each segment to accommodate the curvature independently while maintaining overall structural integrity and alignment stability

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent transitions from mechanically curving a flat FPA to designing a inherently curved FPA structure that maintains its curved shape without creeping back, eliminating time-dependent deformation and wrinkle formation

Inventive Principle:

Principle #14Spheroidality (Curvature)

2Shape

If multiple flat FPAs are stitched together on a curved die to achieve greater curvature, then image quality is improved, but high detail alignment is required and misalignment occurs over time and at excessive temperatures

Engineering Contradiction:

ImprovecurvatureVSAvoidalignment precision

Core Design Contradiction:

ShapeVSManufacturing precision

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent changes the curvature parameter from a mechanical deformation applied to a flat FPA to an inherent structural property of the curved FPA design, allowing the array to maintain its curved shape and alignment under varying temperature and time conditions

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If a flat FPA is excessively curved to achieve sharper images, then image detail is improved, but the FPA may crease or wrinkle

Engineering Contradiction:

Improveimage detailVSAvoidsurface integrity

Core Design Contradiction:

Measurement precisionVSShape

Solution Approach 1:

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The curved FPA design incorporates flexible structural elements that allow the array to achieve and maintain high curvature without creasing or wrinkling, enabling sharper image acquisition while preserving surface integrity

Inventive Principle:

Principle #30Flexible shells and thin films

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

Enables the hybrid focal-plane array to be curved to a greater degree than traditional arrays, improving image quality and operational window by reducing residual tension and maintaining defect-free edges, thus enhancing image acquisition capabilities.

Implementation Method 1

joining the read-out integrated circuit and the detector die to each other

Methodology Applied

Scientific EffectFlip-chip bonding: Welding

Implementation Method 2

both upper and lower surfaces of the hybrid focal-plane array may be lapped and/or etched to reduce the overall thickness

Methodology Applied

Scientific EffectLapping: Abrasion

Implementation Method 3

both upper and lower surfaces of the hybrid focal-plane array may be lapped and/or etched to reduce the overall thickness

Methodology Applied

Scientific EffectEtching: Ablation

Implementation Method 4

the edges of the hybrid focal-plane array are etched to produce nearly defect free edges

Methodology Applied

Scientific EffectEtching: Ablation

Data Source

PatentUS10998372B1Hybrid focal-plane array and method of manufacturing the same

Publication Date: 2021.05.04 HRL LAB

AI summary

A method of manufacturing a hybrid focal-plane array includes: forming a read-out integrated circuit with integral bending slit; forming a detector die separately from the read-out integrated circuit and including a detector with integral bending slit; and joining the read-out integrated circuit and the detector die to each other such that the read-out bending slit and the detector bending slit are aligned with each other.