Circuit Card Assembly with Multi-Material Substrate Regions
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Solution Overview
Problem
In superconducting supercomputers, achieving and maintaining the required operating temperatures for different integrated circuits while minimizing thermal parasitic load and thermal expansion mismatch is challenging, leading to increased costs and potential device damage due to the need for thick substrates and extensive wiring, which slows down processing speed and risks circuit warping.
Innovation Solution
A circuit card assembly with a substantially planar substrate featuring laterally arranged substrate regions made of different materials for circuit traces, allowing for precise temperature control and reduced thermal parasitic load through additive manufacturing, which enables direct longitudinal contact between materials in the same layer, reducing thermal conduction and expansion mismatch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the substrate thickness is increased to connect chips at 4K and 77K, then the thermal conduction parasitic load increases
Solution Approach 1:
The circuit card employs different substrate materials in different regions: a first substrate material (e.g., ceramic) in the first substrate region with first thermal conductivity, and a second substrate material (e.g., polymer) in the second substrate region with second thermal conductivity. This local differentiation allows the card to provide mechanical support and electrical connection reliability where needed while minimizing thermal conduction parasitic load in other areas, thus resolving the contradiction between connection reliability and thermal energy loss.
2Reliability
If the substrate thickness is increased to connect chips at 4K and 77K, then the thermal expansion mismatch stress increases
Solution Approach 1:
The circuit card employs different substrate materials in different regions: a first substrate material (e.g., ceramic) in the first substrate region with first thermal conductivity, and a second substrate material (e.g., polymer) in the second substrate region with second thermal conductivity. This local differentiation allows the card to provide mechanical support and electrical connection reliability where needed while minimizing thermal conduction parasitic load in other areas, thus resolving the contradiction between connection reliability and thermal energy loss.
Solution Approach 2:
The circuit card is constructed as a composite structure with multiple substrate materials having different thermal and mechanical properties. The first substrate material provides thermal stability and mechanical strength, while the second substrate material provides flexibility and stress relief. This composite approach allows the card to withstand thermal expansion mismatch stresses while maintaining chip connection reliability.
3Temperature
If wires extend several feet between hot side and cold side containers, then processing speed decreases
Solution Approach 1:
The patent merges the hot side and cold side containers into a single integrated circuit card structure. Chips operating at different temperatures (4K and 77K) are mounted on the same substrate card, which is divided into thermal zones. This eliminates the need for long external wire connections between separate containers, thereby maintaining processing speed while achieving the required temperature control through the card's internal thermal management design.
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 solution allows for efficient temperature management, minimizing thermal parasitic loads and expansion-related issues, thereby reducing costs, enhancing processing speed, and preventing device damage by using a substrate with strategically placed materials for circuit traces, facilitating effective operation across varying temperature ranges.
Implementation Method 1
the first substrate region, the second substrate region, and the third substrate region have different thermal conductivities
Implementation Method 2
The next issue at cryogenic temperature is the thermal expansion mismatch. Because the metal and dielectric layers are on the same order of thickness, the stress induced by changing temperatures between the two sides of the circuit card may lead to circuit card damage or warping.
Data Source
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AI summary
A circuit card assembly includes a substrate having longitudinally spaced first and second substrate end edges and transversely spaced top and bottom substrate surfaces. The top and/or bottom substrate surface has first, second, and third substrate regions. The first substrate region is directly laterally adjacent the first substrate side edge. The third substrate region is directly laterally adjacent the second substrate side edge. The second substrate region is located between the first and third substrate regions. At least one circuit trace is located on the selected substrate surface. The portion of the circuit trace in the first substrate region is made of only a first material. The portion of the circuit trace in the third substrate region is made of only a second material. The portion of the circuit trace in the second substrate region is made of both the first and second materials. The first material is preferably copper and the second material is preferably niobium.