Microspring Cooling Structures for IC Thermal Management
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Solution Overview
Problem
Current microspring-based electrical contacts for semiconductor dies face limitations in thermal conductivity and mechanical stress management, particularly in compact devices where traditional solder bonding restricts thermal path efficiency and adds complexity and cost.
Innovation Solution
The integration of thermally conductive microspring structures with non-planar profiles and additional thermal elements, such as copper blocks, along with microchannels and thermal transfer fluids, to enhance thermal conduction and reduce mechanical stress, while allowing for reworkable electrical contacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If solder balls are made large to provide mechanical compliance against shear stresses, then mechanical strength is improved, but thermal conductivity deteriorates due to long thermal path
Solution Approach 1:
The thermal management function is segmented from the mechanical bonding function. Microsprings provide mechanical compliance and electrical contact, while separate thermal elements (heat sinks, thermal vias, or substrate structures) provide thermal conduction paths. This segmentation allows each component to be optimized for its specific function without compromise.
Solution Approach 2:
The microspring acts as an intermediary element between the die and substrate, providing mechanical compliance and electrical contact while allowing thermal elements to mediate the thermal transfer separately. The thermal elements serve as intermediary structures that bridge the thermal gap without requiring large solder balls.
2Strength
If solder bonding is used to attach integrated circuits, then mechanical attachment is achieved, but thermal transfer deteriorates due to poor thermal conductivity of underfill material
Solution Approach 1:
The bonding function and thermal transfer function are segmented into separate components. Solder balls or direct attach thermal interfaces provide mechanical attachment, while dedicated thermal elements (such as thermal vias, heat spreaders, or substrate thermal paths) provide thermal transfer. This eliminates reliance on underfill material for thermal conduction.
Solution Approach 2:
The system uses composite structures combining different materials with complementary properties: solder or metallurgical bonds for mechanical attachment, high thermal conductivity materials (copper, aluminum, diamond-like materials) for thermal transfer, and microspring structures for mechanical compliance. This composite approach optimizes both mechanical and thermal performance.
3Temperature
If mechanical heat sinks are mounted to the back of integrated circuit die, then thermal dissipation is improved, but device complexity, weight, and cost increase
Solution Approach 1:
The thermal management function is merged into the existing substrate and interconnect structures. Thermal vias are integrated into the substrate layers, heat spreaders are combined with the substrate or package structure, and thermal paths are routed through existing mechanical components. This eliminates the need for separate attached heat sinks, reducing complexity, weight, and cost.
Solution Approach 2:
Existing substrate and interconnect structures are designed to serve multiple functions: mechanical support, electrical interconnection, and thermal conduction. The substrate acts as a universal platform providing all three functions, eliminating the need for dedicated single-function components like separate heat sinks.
4Strength
If microsprings are used for electrical contact, then mechanical compliance is improved, but thermal conductivity deteriorates compared to solder bonding
Solution Approach 1:
The microspring's primary function of providing mechanical compliance and electrical contact is segmented from the thermal conduction function. Thermal elements are added as separate structures that provide dedicated thermal paths, allowing the microspring to be optimized for mechanical performance while thermal performance is handled by specialized thermal structures.
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 provides improved thermal conductivity and reduced mechanical stress, enabling effective heat dissipation in compact devices without the need for additional heat sinks, while maintaining electrical contact integrity and allowing for easy replacement of defective semiconductor dies.
Implementation Method 1
a thermal element formed of thermally conductive material, formed over said substrate, and configured such that when said thermal and electrical structure is positioned proximate said pad structure with said electrical microspring making electrical contact with an electrical contact pad of said pad structure, said thermal element is in physical contact with said pad structure to permit thermal conduction between said pad structure and said thermal and electrical contact structure
Data Source
AI summary
In a system for providing temporary or permanent connection of an integrated circuit die to a base substrate using electrical microsprings, a thermal element is provided that assists with cooling of the pad structure during use. The thermal element may be formed of the same material and my similar processes as the microsprings. The thermal element may be one or more block structures or one or more thermal microsprings. The thermal element may be provided with channels to contain and/or direct the flow of a thermal transfer fluid. Cooling of components associated with the pad structure (e.g., ICs) may be provided.