Infrared Sensor Bump Layout for Warpage and Crack Resistance
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Solution Overview
Problem
Infrared sensors used in quantum cameras often experience warpage and cracking due to thermal expansion coefficient differences between detection and readout substrates, leading to blurred images and reduced operability.
Innovation Solution
The infrared sensor design includes a detection substrate with infrared detection elements and a readout substrate with a readout circuit, connected by bumps that are partially arranged between adjacent detection elements, which helps to relax stress and reduce warpage by positioning at least one bump in the gaps between electrodes, thereby enhancing mechanical strength and preventing cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bumps are arranged in a lattice shape directly connecting detection elements to readout circuits, then electrical connection is achieved, but warpage and cracks are generated due to thermal expansion differences
Solution Approach 1:
The patent applies asymmetry by arranging bumps in a staggered pattern rather than a symmetric lattice. Specifically, bumps in even-numbered rows are shifted in the column direction relative to bumps in odd-numbered rows, creating an asymmetric distribution that prevents stress concentration and reduces warpage caused by thermal expansion differences between substrates
Solution Approach 2:
The patent introduces a dimensional shift by offsetting bumps not only in the row direction but also in the column direction. This two-dimensional staggering creates a more distributed stress pattern across the substrate, effectively reducing both warpage and crack generation compared to simple one-dimensional alignment
2Weight of moving object
If detection substrate is made thinner to reduce weight, then weight is reduced, but mechanical strength decreases making cracks more likely
Solution Approach 1:
The patent implements preliminary action by pre-positioning bumps in a staggered arrangement before thermal expansion occurs. This pre-configured asymmetric pattern proactively distributes stress to prevent crack initiation, allowing the thin substrate to maintain sufficient mechanical strength without requiring additional reinforcement structures that would increase weight
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 design effectively reduces warpage and cracking in the detection substrate, improving the operability and image quality of infrared sensors by distributing stress and maintaining mechanical strength across the substrate.
Implementation Method 1
a plurality of bumps that electrically connects each one of the plurality of first terminals to one of the plurality of second terminals associated with the one of the plurality of first terminals
Implementation Method 2
a detection unit including infrared detection elements for detecting infrared light arranged in a lattice shape
Implementation Method 3
A quantum infrared camera is used while being cooled with liquid helium or liquid nitrogen
Implementation Method 4
warpage is likely to be generated in an infrared sensor due to a difference in thermal expansion coefficient between a substrate on which infrared detection elements are formed
Data Source
AI summary
An infrared sensor including: a detection substrate that includes a first substrate in which infrared detection elements are arranged in a lattice shape and first terminals each of which is associated with one of the infrared detection elements are arranged; a readout substrate that includes a second substrate in which second terminals each of which is associated with one of the first terminals are arranged and a readout circuit that reads an electrical signal based on infrared light detected by each one of the infrared detection elements is formed; and bumps that electrically connect each one of the first terminals to one of the second terminals associated with the one of the first terminals, in which at least one of the first terminals, the second terminals, or the bumps is partially arranged at a position between the infrared detection elements that are adjacent in a top view.