Quantum Device Bonding Structure for Heat Transfer and Stress Relief
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Solution Overview
Problem
Conventional laminated structures face challenges in simultaneously achieving high thermal conductivity and mitigating thermal stress due to large differences in thermal expansion coefficients between bonding materials and circuit boards, leading to potential die cracking and altered circuit characteristics.
Innovation Solution
A laminated structure with a bonding material comprising a first bonding portion with high thermal conductivity and a second bonding portion with lower elastic modulus, where the first bonding portion is in contact with both the cooling member and device surfaces, and the second bonding portion surrounds the first, providing improved thermal conductivity and stress mitigation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a metal material such as silver is used as a bonding material to improve thermal conductivity, then heat transmission efficiency is improved, but thermal stress increases due to large difference in thermal expansion coefficients
Solution Approach 1:
The bonding material is divided into two portions with different material properties: the first bonding portion (central region) uses material with high thermal conductivity for efficient heat transmission, while the second bonding portion (peripheral region) uses material with low elastic modulus to reduce thermal stress. This local differentiation allows each region to perform its specific function optimally.
Solution Approach 2:
The bonding material comprises a composite structure with two distinct portions having different material compositions and properties. The first bonding portion contains materials optimized for thermal conductivity, while the second bonding portion contains materials optimized for stress mitigation, creating a composite bonding system that achieves both thermal efficiency and mechanical reliability.
2Stress or pressure
If a resin such as epoxy is used as a bonding material to reduce thermal stress, then thermal stress is mitigated due to lower elastic modulus, but thermal conductivity deteriorates making it difficult to maintain qubit temperature
Solution Approach 1:
The bonding material is divided into two portions with different material properties: the first bonding portion (central region) uses material with high thermal conductivity for efficient heat transmission, while the second bonding portion (peripheral region) uses material with low elastic modulus to reduce thermal stress. This local differentiation allows each region to perform its specific function optimally.
Solution Approach 2:
The bonding material comprises a composite structure with two distinct portions having different material compositions and properties. The first bonding portion contains materials optimized for thermal conductivity, while the second bonding portion contains materials optimized for stress mitigation, creating a composite bonding system that achieves both thermal efficiency and mechanical reliability.
3Ease of manufacture
If a single bonding material is used to bond the circuit board and device, then manufacturing is simplified, but both high thermal conductivity and thermal stress mitigation cannot be achieved simultaneously
Solution Approach 1:
The bonding material is divided into two portions with different material properties: the first bonding portion (central region) uses material with high thermal conductivity for efficient heat transmission, while the second bonding portion (peripheral region) uses material with low elastic modulus to reduce thermal stress. This local differentiation allows each region to perform its specific function optimally.
Solution Approach 2:
The bonding material comprises a composite structure with two distinct portions having different material compositions and properties. The first bonding portion contains materials optimized for thermal conductivity, while the second bonding portion contains materials optimized for stress mitigation, creating a composite bonding system that achieves both thermal efficiency and mechanical reliability.
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 structure effectively enhances thermal conductivity while reducing thermal stress, maintaining qubit temperature and preventing die cracking.
Implementation Method 1
a thermal conductivity of the first bonding portion is higher than a thermal conductivity of the second bonding portion
Implementation Method 2
an elastic modulus of the second bonding portion is lower than an elastic modulus of the first bonding portion
Data Source
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AI summary
A laminated structure includes a cooling member; a circuit board provided on the cooling member and formed with a through hole; a device provided on the circuit board and including a quantum bit; and a bonding material configured to bond the circuit board and the device to each other, wherein the bonding material includes a first bonding portion in contact with a portion of an upper surface of the cooling member exposed from the through hole, an upper surface of the circuit board, and a lower surface of the device; and a second bonding portion provided around the first bonding portion in plan view and in contact with at least the upper surface of the circuit board and the lower surface of the device, and wherein a thermal conductivity of the first bonding portion is higher than a thermal conductivity of the second bonding portion, and an elastic modulus of the second bonding portion is lower than an elastic modulus of the first bonding portion. The laminated structure can be used for quantum computing, for example.