Encapsulated Liquid Thermal Interface for Uniform Subassembly Pressure
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Solution Overview
Problem
In array packaging of electronic components, variations in dimensions and materials lead to differential heat generation, heat flux, and temperature-related issues, causing thermal and mechanical stresses that can diminish performance and lead to component failure, especially in optomechanical assemblies sensitive to temperature and mechanical misalignment.
Innovation Solution
A cooling system utilizing a thermally conductive cold plate with encapsulated liquid thermal interfaces (LTIs) that maintain constant pressure and minimize shear on subassemblies, ensuring uniform stress and strain across all components, with a flexible housing and thermally conductive fluid connecting all LTIs in the array.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If array packaging is used to reduce cooling costs, then productivity is improved, but manufacturing precision deteriorates due to dimensional and material variations causing thermal and mechanical stresses
Solution Approach 1:
The patent applies parameter changes by using a compliant thermal interface material that changes its mechanical properties (compliance) to accommodate dimensional variations. The CTE-matched compliant material adjusts its stiffness and stress distribution to compensate for manufacturing tolerances in subassembly dimensions, thereby maintaining thermal contact while reducing stress transmission to sensitive components.
Solution Approach 2:
The patent utilizes thermal expansion principles by employing a compliant material with a coefficient of thermal expansion (CTE) that matches the subassemblies. This CTE matching ensures that the interface material expands and contracts at the same rate as the subassemblies during temperature cycles, preventing differential expansion stresses that would otherwise damage optomechanical components while maintaining thermal contact.
2Device complexity
If subassemblies with dimensional variations are packaged together, then device complexity is reduced, but reliability deteriorates due to differential heating and thermal stresses
Solution Approach 1:
The compliant thermal interface material changes its mechanical parameters (stiffness, compliance) to adapt to dimensional variations in subassemblies. This parameter adaptation allows the system to accommodate manufacturing tolerances without compromising reliability, as the material maintains optimal thermal contact while distributing mechanical stresses away from sensitive optomechanical components.
Solution Approach 2:
By matching the CTE of the compliant material to that of the subassemblies, the patent ensures that all components expand and contract uniformly during thermal cycling. This eliminates differential thermal expansion that would cause stress concentration and component failure, thereby improving reliability while maintaining a simple packaging structure.
3Productivity
If optomechanical assemblies are used for high speed communication, then productivity is improved, but sensitivity to temperature and mechanical misalignment worsens reliability
Solution Approach 1:
The CTE-matched compliant material compensates for thermal expansion differences between the subassembly and the interface material. During high-speed communication operations that generate heat, the material expands at the same rate as the subassembly, maintaining precise mechanical alignment of optomechanical components and preventing misalignment-induced reliability issues.
Solution Approach 2:
The compliant material dynamically adjusts its mechanical parameters in response to thermal and mechanical loads. This parameter adaptation ensures that optomechanical assemblies maintain their alignment precision and operational reliability even under the thermal and mechanical stresses generated during high-speed communication operations.
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 effectively transfers heat from subassemblies to the cold plate while maintaining consistent pressure and minimizing mechanical stress, thereby enhancing the reliability and longevity of electronic components by reducing thermal and mechanical fluctuations.
Implementation Method 1
heat is transferred to a cold plate from one or more subassemblies in an array of subassemblies in an electronic package
Implementation Method 2
The system transfers heat from the subassemblies to the cold plate while maintaining a constant pressure/stress on each of the subassemblies
Data Source
AI summary
Heat is transferred to a cold plate from one or more subassemblies in an array of subassemblies in an electronic package. The cold plate has a thermally conductive cold plate substrate, a pressure header, a pressure passage, and one or more pressure connections. Each of the pressure connections connects through a housing opening to housing volume defined by a flexible housing in an encapsulated liquid thermal interface (LTI). The flexible housing is in physical and thermal contact with one of the subassemblies through a housing bottom and a top surface of one or more components in the subassembly. A thermally conductive fluid fills the housing volume, housing opening, pressure connections, pressure passage, and pressure header which are all in fluid communication along with one or more other connections, housing openings, and LTIs on other subassemblies. The system transfers heat from the subassemblies to the cold plate while maintaining a constant pressure/stress on each of the subassemblies. The system pressure on each of the subassemblies is equal. The system pressure can be controlled to a preloaded pressure to insure good electrical contact between components. Shear on the subassemblies is minimized by the LTIs.